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Verbanck, Sylvia, Daniël Schuermans, Marc Noppen, Walter Vincken e Manuel Paiva. "Methacholine versus histamine: paradoxical response of spirometry and ventilation distribution". Journal of Applied Physiology 91, n.º 6 (1 de dezembro de 2001): 2587–94. http://dx.doi.org/10.1152/jappl.2001.91.6.2587.
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We investigated the differential effect of histamine and methacholine on spirometry and ventilation distribution (where indexes S cond and S acin represent conductive and acinar ventilation heterogeneity; Verbanck S, Schuermans D, Van Muylem A, Noppen M, Paiva M, and Vincken W. J Appl Physiol 83: 1807–1816, 1997). Thirty normal subjects were challenged with cumulative doses of 6.52 μmol histamine and, on a separate day, with either 6.67 μmol methacholine (equal-dose group; n = 15) or 13.3 μmol methacholine (double-dose group; n = 15). Largest average forced expiratory volume in 1 s (FEV1) decreases or S cond increases obtained in either group were −9% and +286%, respectively; S acin remained unaffected at all times. In the equal-dose group, a smaller FEV1 decline ( P= 0.002) after methacholine was paralleled by a smaller S cond increase ( P = 0.041) than with histamine. However, in the double-dose group, methacholine maintained a smaller FEV1 decline ( P = 0.009) while inducing a larger S cond increase ( P = 0.006) than did histamine. The differential action of histamine and methacholine is confined to the conductive airways, where histamine likely causes the greatest overall airway narrowing and methacholine induces the largest parallel heterogeneity in airway narrowing, probably at the level of the large and small conductive airways, respectively. The observed ventilation heterogeneities predict a risk for dissociation between ventilation-perfusion mismatch and spirometry, particularly after methacholine challenge.
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Winkler, Tilo, e Jose G. Venegas. "Complex airway behavior and paradoxical responses to bronchoprovocation". Journal of Applied Physiology 103, n.º 2 (agosto de 2007): 655–63. http://dx.doi.org/10.1152/japplphysiol.00041.2007.
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Heterogeneity of airway constriction and regional ventilation in asthma are commonly studied under the paradigm that each airway's response is independent from other airways. However, some paradoxical effects and contradictions in recent experimental and theoretical findings suggest that considering interactions among serial and parallel airways may be necessary. To examine airway behavior in a bronchial tree with 12 generations, we used an integrative model of bronchoconstriction, including for each airway the effects of pressure, tethering forces, and smooth muscle forces modulated by tidal stretching during breathing. We introduced a relative smooth muscle activation factor (Tr) to simulate increasing and decreasing levels of activation. At low levels of Tr, the model exhibited uniform ventilation and homogeneous airway narrowing. But as Tr reached a critical level, the airway behavior suddenly changed to a dual response with a combination of constriction and dilation. Ventilation decreased dramatically in a group of terminal units but increased in the rest. A local increase of Tr in a single central airway resulted in full closure, while no central airway closed under global elevation of Tr. Lung volume affected the response to both local and global stimulation. Compared with imaging data for local and global stimuli, as well as for the time course of airway lumen caliber during bronchoconstriction recovery, the model predictions were similar. The results illustrate the relevance of dynamic interactions among serial and parallel pathways in airway interdependence, which may be critical for the understanding of pathological conditions in asthma.
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Kinnear, William J. M., Milind Sovani, Arun Khanna e Juliet Colt. "Correction of Paradoxical Ribcage Motion in Scoliosis by Noninvasive Ventilation". SPINE 43, n.º 13 (julho de 2018): 900–904. http://dx.doi.org/10.1097/brs.0000000000002467.
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Jordahn, Zarah, Cheme Andersen, Anne Marie Roust Aaberg e Frank Christian Pott. "Reversal of a Suspected Paradoxical Reaction to Zopiclone with Flumazenil". Case Reports in Critical Care 2016 (2016): 1–3. http://dx.doi.org/10.1155/2016/3185873.
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We describe the care for an elderly woman who was admitted to the intensive care unit (ICU) to receive noninvasive ventilation for acute exacerbation of chronic obstructive pulmonary disease. After administration of the sleeping pill zopiclone, a nonbenzodiazepine receptor agonist (NBRA), the patient became agitated and was confused, a possible paradoxical reaction to benzodiazepines. These symptoms were immediately resolved after treatment with flumazenil, usually used to reverse the adverse effects of benzodiazepines or NBRAs and to reverse paradoxical reactions to benzodiazepines. This case indicates that zopiclone induced behavioral changes resembling a paradoxical reaction to benzodiazepines and these symptoms may be treated with flumazenil.
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Perry, Michael E., e Antonio Vila. "A SIMPLE MODEL OF PARADOXICAL VENTILATION AND DIFFUSION-LIMITED GAS EXCHANGE". Chest 128, n.º 4 (outubro de 2005): 394S. http://dx.doi.org/10.1378/chest.128.4_meetingabstracts.394s-b.
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Bayat, Sam, Liisa Porra, Heikki Suhonen, Pekka Suortti e Anssi R. A. Sovijärvi. "Paradoxical conducting airway responses and heterogeneous regional ventilation after histamine inhalation in rabbit studied by synchrotron radiation CT". Journal of Applied Physiology 106, n.º 6 (junho de 2009): 1949–58. http://dx.doi.org/10.1152/japplphysiol.90550.2008.
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We studied both central conducting airway response and changes in the distribution of regional ventilation induced by inhaled histamine in healthy anesthetized and mechanically ventilated rabbit using a novel xenon-enhanced synchrotron radiation computed tomography (CT) imaging technique, K-edge subtraction imaging (KES). Images of specific ventilation were obtained using serial KES during xenon washin, in three axial lung slices, at baseline and twice after inhalation of histamine aerosol (50 or 125 mg/ml) in two groups of animals ( n = 6 each). Histamine inhalation caused large clustered areas of poor ventilation, characterized by a drop in average specific ventilation (sV̇m), but an increase in sV̇m in the remaining lung zones indicating ventilation redistribution. Ventilation heterogeneity, estimated as coefficient of variation (CV) of sV̇m significantly increased following histamine inhalation. The area of ventilation defects and CV were significantly larger with the higher histamine dose. In conducting airways, histamine inhalation caused a heterogeneous airway response combining narrowing and dilatation in individual airways of different generations, with the probability for constriction increasing peripherally. This finding provides further in vivo evidence that airway reactivity in response to inhaled histamine is complex and that airway response may vary substantially with location within the bronchial tree.
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BRAHMANDAM, SRAVYA, e TIMOTHY JANZ. "PARADOXICAL WORSENING HYPOXEMIA WITH MECHANICAL VENTILATION IN A PATIENT WITH BILATERAL PNEUMONIA". Chest 154, n.º 4 (outubro de 2018): 968A. http://dx.doi.org/10.1016/j.chest.2018.08.880.
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Bhaskar, Pradeep, Reyaz A. Lone, Ahmad Sallehuddin, Jiju John, Akhlaque N. Bhat e Muhammed R. K. Rahmath. "Bilateral diaphragmatic palsy after congenital heart surgery: management options". Cardiology in the Young 26, n.º 5 (8 de setembro de 2015): 927–30. http://dx.doi.org/10.1017/s1047951115001559.
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AbstractDiaphragmatic paralysis following phrenic nerve injury is a major complication following congenital cardiac surgery. In contrast to unilateral paralysis, patients with bilateral diaphragmatic paralysis present a higher risk group, require different management methods, and have poorer prognosis. We retrospectively analysed seven patients who had bilateral diaphragmatic paralysis following congenital heart surgery during the period from July, 2006 to July, 2014. Considerations were given to the time to diagnosis of diaphragm paralysis, total ventilator days, interval after plication, and lengths of ICU and hospital stays. The incidence of bilateral diaphragmatic paralysis was 0.68% with a median age of 2 months (0.6–12 months). There was one neonate and six infants with a median weight of 4 kg (3–7 kg); five patients underwent unilateral plication of the paradoxical diaphragm following recovery of the other side, whereas the remaining two patients who did not demonstrate a paradoxical movement were successfully weaned from the ventilator following recovery of function in one of the diaphragms. The median ventilation time for the whole group was 48 days (20–90 days). The median length of ICU stay was 46 days (24–110 days), and the median length of hospital stay was 50 days (30–116 days). None of the patients required tracheostomy for respiratory support and there were no mortalities, although all the patients except one developed ventilator-associated pneumonia. The outcome of different management options for bilateral diaphragmatic paralysis following surgery for CHD is discussed.
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Kinkead, R., e W. Milsom. "CO2-sensitive olfactory and pulmonary receptor modulation of episodic breathing in bullfrogs". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 270, n.º 1 (1 de janeiro de 1996): R134—R144. http://dx.doi.org/10.1152/ajpregu.1996.270.1.r134.
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Breathing was monitored during normocarbia, hypercarbia (6% CO2 in air), and the period immediately after the return to normocarbic conditions in intact, olfactory-denervated, and vagotomized bullfrogs. In intact frogs, ventilation increased during hypercarbia, but the breathing pattern remained episodic. Immediately upon return to air, there was a further paradoxical increase in breathing frequency, and breathing became continuous in most frogs. Results obtained from animals after olfactory receptor denervation indicate that tonic stimulation of olfactory receptors by airway CO2 inhibited breathing during hypercarbia. Measurements of the kinetics of changes in airway and arterial blood CO2 levels support the suggestion that the sudden release of this inhibition on the return to normocarbic conditions was responsible for the posthypercarbic hyperpnea. Vagotomy increased ventilation during normocarbia. Hypercarbia now caused a change in breathing pattern but had no net effect on total ventilation, suggesting that pulmonary vagal feedback inhibited ventilation during normocarbia but stimulated ventilation during hypercarbia. Although olfactory and pulmonary receptor feed-back shape the breathing pattern, they were not responsible for initiating or terminating the episodes of breathing.
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Wang, Simon, e Stuart M. McGill. "Links between the Mechanics of Ventilation and Spine Stability". Journal of Applied Biomechanics 24, n.º 2 (maio de 2008): 166–74. http://dx.doi.org/10.1123/jab.24.2.166.
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Spine stability is ensured through isometric coactivation of the torso muscles; however, these same muscles are used cyclically to assist ventilation. Our objective was to investigate this apparent paradoxical role (isometric contraction for stability or rhythmic contraction for ventilation) of some selected torso muscles that are involved in both ventilation and support of the spine. Eight, asymptomatic, male subjects provided data on low back moments, motion, muscle activation, and hand force. These data were input to an anatomically detailed, biologically driven model from which spine load and a lumbar spine stability index was obtained. Results revealed that subjects entrained their torso stabilization muscles to breathe during demanding ventilation tasks. Increases in lung volume and back extensor muscle activation coincided with increases in spine stability, whereas declines in spine stability were observed during periods of low lung inflation volume and simultaneously low levels of torso muscle activation. As a case study, aberrant ventilation motor patterns (poor muscle entrainment), seen in one subject, compromised spine stability. Those interested in rehabilitation of patients with lung compromise and concomitant back troubles would be assisted with knowledge of the mechanical links between ventilation during tasks that impose spine loading.
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Farmer, C. G., e D. R. Carrier. "Ventilation and gas exchange during treadmill locomotion in the American alligator (Alligator mississippiensis)". Journal of Experimental Biology 203, n.º 11 (1 de junho de 2000): 1671–78. http://dx.doi.org/10.1242/jeb.203.11.1671.
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A number of anatomical characters of crocodilians appear to be inconsistent with their lifestyle as sit-and-wait predators. To address this paradoxical association of characters further, we measured lung ventilation and respiratory gas exchange during walking in American alligators (Alligator mississippiensis). During exercise, ventilation consisted of low-frequency, large-volume breaths. The alligators hyperventilated severely during walking with respect to their metabolic demands. Air convection requirements were among the highest and estimates of lung P(CO2) were among the lowest known in air-breathing vertebrates. Air convection requirements dropped immediately with cessation of exercise. These observations indicate that the ventilation of alligators is not limited by their locomotor movements. We suggest that the highly specialized ventilatory system of modern crocodilians represents a legacy from cursorial ancestors rather than an adaptation to a lifestyle as amphibious sit-and-wait predators.
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Millman, R. P., H. Knight, L. R. Kline, E. T. Shore, D. C. Chung e A. I. Pack. "Changes in compartmental ventilation in association with eye movements during REM sleep". Journal of Applied Physiology 65, n.º 3 (1 de setembro de 1988): 1196–202. http://dx.doi.org/10.1152/jappl.1988.65.3.1196.
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The effect of phasic eye movement activity on ventilation during rapid-eye-movement (REM) sleep was studied in seven healthy young adults by use of the respiratory inductive plethysmograph. Mean ventilation (VE) and ventilatory components during REM sleep were not significantly different from that seen in either stages 1-2 or 3-4 sleep. The percent of rib cage contribution to ventilation in REM sleep, 29.3 +/- 5.1%, was reduced compared with 54.4 +/- 5.8% in stage 1-2 and 52.2 +/- 4.3% in stage 3-4 sleep (P less than 0.005). When one separated breaths by the degree of associated phasic eye movement activity, it became apparent that breathing during REM sleep is very heterogeneous. Increasing eye movement activity was associated with inhibition of ventilation with a reduction in VE from 5.1 +/- 0.3 to 3.8 +/- 0.3 l/min. Tidal volume and frequency both fell, whereas inspiratory duration was unchanged. Compartmental ventilation was also affected, with the fall in the rib cage contribution from 37.8 +/- 6.4 to 15.3 +/- 5.6%. Chest wall and abdominal movement became more asynchronous as phasic-eye-movement activity increased and frank paradoxical breathing was seen.
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Bennett, Johan, Li Ong e Colm Hanratty. "Paradoxical coronary embolism, a rare cause of acute myocardial infarction on positive pressure ventilation". Acta Cardiologica 67, n.º 4 (agosto de 2012): 477–79. http://dx.doi.org/10.1080/ac.67.4.2170693.
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Vasudevan, Srikanth, Shriram Vaidya, Ritu Baath S., Ashok Basur C., Anantheswar Yellambalase N. e Sudarshan Reddy Nagireddy. "Temporary Extrathoracic Vacuum Therapy Splint in Chest Wall Reconstruction". Indian Journal of Plastic Surgery 54, n.º 02 (abril de 2021): 211–14. http://dx.doi.org/10.1055/s-0041-1729502.
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Abstract Background Paradoxical respiration is a sinister consequence of bony chest cage defects which can persist even post chest wall reconstruction. It leads to prolonged dependence on mechanical ventilation postoperatively, thereby delaying recovery. Methods Negative pressure wound therapy (NPWT) was applied in early postoperative period to a patient with chest wall defect reconstructed with folded prolene mesh and free anterolateral thigh flap. Arterial blood gas (ABG), fraction of inspired oxygen (FiO2), peak end expiratory pressure (PEEP), oxygen saturation (SpO2), and blood pressure (BP) readings pre and post NPWT application were compared. Results There was marked improvement in the breathing mechanics and related parameters post NPWT application over the flap. Conclusions Negative extrathoracic pressure in the form of a temporary splint can enable early weaning off the ventilator and a smoother postoperative recovery in reconstructed chest wall defects.
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Hackett, P. H., R. C. Roach, R. B. Schoene, G. L. Harrison e W. J. Mills. "Abnormal control of ventilation in high-altitude pulmonary edema". Journal of Applied Physiology 64, n.º 3 (1 de março de 1988): 1268–72. http://dx.doi.org/10.1152/jappl.1988.64.3.1268.
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We wished to determine the role of hypoxic chemosensitivity in high-altitude pulmonary edema (HAPE) by studying persons when ill and upon recovery. We studied seven males with HAPE and seventeen controls at 4,400 m on Mt. McKinley. We measured ventilatory responses to both O2 breathing and progressive poikilocapnic hypoxia. Hypoxic ventilatory response (HVR) was described by the slope relating minute ventilation to percent arterial O2 saturation (delta VE/delta SaO2%). HAPE subjects were quite hypoxemic (SaO2% 59 ± 6 vs. 85 ± 1, P less than 0.01) and showed a high-frequency, low-tidal-volume pattern of breathing. O2 decreased ventilation in controls (-20%, P less than 0.01) but not in HAPE subjects. The HAPE group had low HVR values (0.15 ± 0.07 vs. 0.54 ± 0.08, P less than 0.01), although six controls had values in the same range. The three HAPE subjects with the lowest HVR values were the most hypoxemic and had a paradoxical increase in ventilation when breathing O2. We conclude that a low HVR plays a permissive rather than causative role in the pathogenesis of HAPE and that the combination of extreme hypoxemia and low HVR may result in hypoxic depression of ventilation.
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Heldt, G. P., e M. B. McIlroy. "Distortion of chest wall and work of diaphragm in preterm infants". Journal of Applied Physiology 62, n.º 1 (1 de janeiro de 1987): 164–69. http://dx.doi.org/10.1152/jappl.1987.62.1.164.
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Chest wall distortion is common in infants and is especially visible in preterm infants. It has been suggested that this distortion increases the volume displacement of the diaphragm during inspiration, which may be associated with muscular fatigue and apnea. We studied 10 preterm infants who had no evidence of lung disease, investigating the effect of chest wall distortion on the volume displacement and work of the diaphragm. The volume changes of the respiratory system were partitioned using an inductance plethysmograph. The minute volume displacement and the work of the diaphragm were calculated using the partitioned abdominal volume change and the gastric and esophageal pressures. The paradoxical movement of the chest wall lasted an average of 36% of inspiration. The minute volume displacement of the diaphragm ranged from 72 to 176% of the minute pulmonary ventilation, and diaphragmatic work ranged from 94 to 793% of that performed on the lungs. The amount of chest wall distortion, as reflected by the duration of the paradoxical chest wall movement, the minute volume excursion, or work of the diaphragm, was not related to the mechanical properties of the lungs. This estimated work load may represent a significant expenditure of calories in these infants and may contribute to the development of diaphragmatic fatigue, apnea, and a prolonged need for mechanical ventilation.
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Caramez, Maria Paula, Joao B. Borges, Mauro R. Tucci, Valdelis N. Okamoto, Carlos R. R. Carvalho, Robert M. Kacmarek, Atul Malhotra, Irineu Tadeu Velasco e Marcelo B. P. Amato. "Paradoxical responses to positive end-expiratory pressure in patients with airway obstruction during controlled ventilation*". Critical Care Medicine 33, n.º 7 (julho de 2005): 1519–28. http://dx.doi.org/10.1097/01.ccm.0000168044.98844.30.
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Dellinger, R. P. "Paradoxical Responses to Positive End-Expiratory Pressure in Patients With Airway Obstruction During Controlled Ventilation". Yearbook of Critical Care Medicine 2006 (janeiro de 2006): 9–10. http://dx.doi.org/10.1016/s0734-3299(08)70011-x.
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Eumorfia, Kondili, C. Alexopoulou, G. Prinianakis, N. Xirouchaki e D. Georgopoulos. "In Patients with Obstructive Pulmonary Disease During Controlled Ventilation, PEEP Decreases Dynamic Hyperinflation: Is This Response Really “Paradoxical”?" Critical Care Medicine 33, n.º 12 (dezembro de 2005): 2860. http://dx.doi.org/10.1097/01.ccm.0000191255.77119.a2.
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David Maksimovich, Dr. Cihan Cevik e Christopher Micheal Merrick. "PFO closure consideration for refractory hypoxia and secondary prevention of recurrent arterial thromboembolism". Southwest Respiratory and Critical Care Chronicles 7, n.º 31 (20 de outubro de 2019): 49–51. http://dx.doi.org/10.12746/swrccc.v7i31.579.
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Acute arterial and deep venous thrombosis presenting simultaneously are uncommon medical emergencies, usually secondary to an underlying cause. We present a 64-year-old woman with concurrent bilateral pulmonary embolisms and acute thrombotic occlusion of the right brachial artery. Her work-up revealed a large patent foramen ovale (PFO), with a right to left intracardiac shunt and bilateral lower extremity deep venous thrombosis. The patient was unable to be weaned off mechanical ventilation due to her refractory hypoxia. However, after closure of the PFO the patient’s oxygenation improved. This case demonstrates the potential beneficial role of PFO closure in a hypoxic patient with a right to left intracardiac shunt. In addition, closure of the PFO may provide secondary prevention of paradoxical systemic thromboembolism.
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Dubsky, S., G. R. Zosky, K. Perks, C. R. Samarage, Y. Henon, S. B. Hooper e A. Fouras. "Assessment of airway response distribution and paradoxical airway dilation in mice during methacholine challenge". Journal of Applied Physiology 122, n.º 3 (1 de março de 2017): 503–10. http://dx.doi.org/10.1152/japplphysiol.00476.2016.
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Detailed information on the distribution of airway diameters during bronchoconstriction in situ is required to understand the regional response of the lungs. Imaging studies using computed tomography (CT) have previously measured airway diameters and changes in response to bronchoconstricting agents, but the manual measurements used have severely limited the number of airways measured per subject. Hence, the detailed distribution and heterogeneity of airway responses are unknown. We have developed and applied dynamic imaging and advanced image-processing methods to quantify and compare hundreds of airways in vivo. The method, based on CT, was applied to house dust-mite-sensitized and control mice during intravenous methacholine (MCh) infusion. Airway diameters were measured pre- and post-MCh challenge, and the results compared demonstrate the distribution of airway response throughout the lungs during mechanical ventilation. Forced oscillation testing was used to measure the global response in lung mechanics. We found marked heterogeneity in the response, with paradoxical dilation of airways present at all airway sizes. The probability of paradoxical dilation decreased with decreasing baseline airway diameter and was not affected by pre-existing inflammation. The results confirm the importance of considering the lung as an entire interconnected system rather than a collection of independent units. It is hoped that the response distribution measurements can help to elucidate the mechanisms that lead to heterogeneous airway response in vivo. NEW & NOTEWORTHY Information on the distribution of airway diameters during bronchoconstriction in situ is critical for understanding the regional response of the lungs. We have developed an imaging method to quantify and compare the size of hundreds of airways in vivo during bronchoconstriction in mice. The results demonstrate large heterogeneity with both constriction and paradoxical dilation of airways, confirming the importance of considering the lung as an interconnected system rather than a collection of independent units.
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Shapiro, J. I., M. Whalen, R. Kucera, N. Kindig, G. Filley e L. Chan. "Brain pH responses to sodium bicarbonate and Carbicarb during systemic acidosis". American Journal of Physiology-Heart and Circulatory Physiology 256, n.º 5 (1 de maio de 1989): H1316—H1321. http://dx.doi.org/10.1152/ajpheart.1989.256.5.h1316.
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Rats subjected to ammonium chloride-induced metabolic acidosis or respiratory acidosis caused by hypercapnia were given alkalinization therapy with either sodium bicarbonate or Carbicarb. Ammonium chloride induced dose-dependent systemic acidosis but did not affect intracellular brain pH. Hypercapnia caused dose-dependent systemic acidosis as well as decreases in intracellular brain pH. Sodium bicarbonate treatment resulted in systemic alkalinization and increases in arterial PCO2 in both acidosis models, but it caused intracellular brain acidification in rats with ammonium chloride acidosis. Carbicarb therapy resulted in systemic alkalinization without major changes in arterial PCO2 and intracellular brain alkalinization in both acidosis models. These data demonstrate that bicarbonate therapy of systemic acidosis may be associated with "paradoxical" intracellular brain acidosis, whereas Carbicarb causes both systemic and intracellular alkalinization under conditions of fixed ventilation.
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Kuypers, Kristel, Tessa Martherus, Tereza Lamberska, Janneke Dekker, Stuart B. Hooper e Arjan B. te Pas. "Reflexes that impact spontaneous breathing of preterm infants at birth: a narrative review". Archives of Disease in Childhood - Fetal and Neonatal Edition 105, n.º 6 (29 de abril de 2020): 675–79. http://dx.doi.org/10.1136/archdischild-2020-318915.
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Some neural circuits within infants are not fully developed at birth, especially in preterm infants. Therefore, it is unclear whether reflexes that affect breathing may or may not be activated during the neonatal stabilisation at birth. Both sensory reflexes (eg, tactile stimulation) and non-invasive ventilation (NIV) can promote spontaneous breathing at birth, but the application of NIV can also compromise breathing by inducing facial reflexes that inhibit spontaneous breathing. Applying an interface could provoke the trigeminocardiac reflex (TCR) by stimulating the trigeminal nerve resulting in apnoea and a reduction in heart rate. Similarly, airflow within the nasopharynx can elicit the TCR and/or laryngeal chemoreflex (LCR), resulting in glottal closure and ineffective ventilation, whereas providing pressure via inflations could stimulate multiple receptors that affect breathing. Stimulating the fast adapting pulmonary receptors may activate Head’s paradoxical reflex to stimulate spontaneous breathing. In contrast, stimulating the slow adapting pulmonary receptors or laryngeal receptors could induce the Hering-Breuer inflation reflex or LCR, respectively, and thereby inhibit spontaneous breathing. As clinicians are most often unaware that starting primary care might affect the breathing they intend to support, this narrative review summarises the currently available evidence on (vagally mediated) reflexes that might promote or inhibit spontaneous breathing at birth.
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Burggren, W. W., J. E. Bicudo, M. L. Glass e A. S. Abe. "Development of blood pressure and cardiac reflexes in the frog Pseudis paradoxsus". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 263, n.º 3 (1 de setembro de 1992): R602—R608. http://dx.doi.org/10.1152/ajpregu.1992.263.3.r602.
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Systemic arterial blood pressure and heart rate (fH) were measured in unanesthetized, unrestrained larvae and adults of the paradoxical frog, Pseudis paradoxus from Sao Paulo State in Brazil. Four developmental groups were used, representing the complete transition from aquatic larvae to primarily air-breathing adults. fH (49-66 beats/min) was not significantly affected by development, whereas mean arterial blood pressure was strongly affected, being lowest in the stage 37-39 larvae (10 mmHg), intermediate in the stage 44-45 larvae (18 mmHg), and highest in the juveniles and adults (31 and 30 mmHg, respectively). Blood pressure was not significantly correlated with body mass, which was greatest in the youngest larvae and smallest in the juveniles. In the youngest larvae studied (stages 37-39), lung ventilation was infrequent, causing a slight decrease in arterial blood pressure but no change in heart rate. Lung ventilation was more frequent in stages 44-45 larvae and nearly continuous in juveniles and adults floating at the surface. Bradycardia during both forced and voluntary diving was observed in almost every advanced larva, juvenile, and adult but in only one of four young larvae. Developmentally related changes in blood pressure were not complete until metamorphosis, whereas diving bradycardia was present at an earlier stage.
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Curran, Linda S., Jianguo Zhuang, Shin Fu Sun e Lorna G. Moore. "Ventilation and hypoxic ventilatory responsiveness in Chinese-Tibetan residents at 3,658 m". Journal of Applied Physiology 83, n.º 6 (1 de dezembro de 1997): 2098–104. http://dx.doi.org/10.1152/jappl.1997.83.6.2098.
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Curran, Linda S., Jianguo Zhuang, Shin Fu Sun, and Lorna G. Moore. Ventilation and hypoxic ventilatory responsiveness in Chinese-Tibetan residents at 3,658 m. J. Appl. Physiol. 83(6): 2098–2104, 1997.—When breathing ambient air at rest at 3,658 m altitude, Tibetan lifelong residents of 3,658 m ventilate as much as newcomers acclimatized to high altitude; they also ventilate more and have greater hypoxic ventilatory responses (HVRs) than do Han (“Chinese”) long-term residents at 3,658 m. This suggests that Tibetan ancestry is advantageous in protecting resting ventilation levels during years of hypoxic exposure and is of interest in light of the permissive role of hypoventilation in the development of chronic mountain sickness, which is nearly absent among Tibetans. The existence of individuals with mixed Tibetan-Chinese ancestry (Han-Tibetans) residing at 3,658 m affords an opportunity to test this hypothesis. Eighteen men born in Lhasa, Tibet, China (3,658 m) to Tibetan mothers and Han fathers were compared with 27 Tibetan men and 30 Han men residing at 3,658 m who were previously studied. We used the same study procedures (minute ventilation was measured with a dry-gas flowmeter during room air breathing and hyperoxia and with a 13-liter spirometer-rebreathing system during the hypoxic and hypercapnic tests). During room air breathing at 3,658 m (inspired O2 pressure = 93 Torr), Han-Tibetans resembled Tibetans in ventilation (12.1 ± 0.6 vs. 11.5± 0.5 l/min btps, respectively) but had HVR that were blunted (63 ± 16 vs. 121 ± 13, respectively, for HVR shape parameter A) and declined with increasing duration of high-altitude residence. During administered hyperoxia (inspired O2 pressure = 310 Torr) at 3,658 m, the paradoxical hyperventilation previously seen in Tibetan but not Han residents at 3,658 m (11.8 ± 0.5 vs. 10.1 ± 0.5 l/min btps) was absent in these Han-Tibetans (9.8 ± 0.6 l/minbtps). Thus, although longer duration of high-altitude residence appears to progressively blunt HVR among Han-Tibetans born and residing at 3,658 m, their Tibetan ancestry appears protective in their maintenance of high resting ventilation levels despite diminished chemosensitivity.
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Popova, L. A., E. A. Shergina, T. P. Bagdasaryan, I. Yu Shabalina, M. I. Chushkin e N. L. Karpina. "The change of ventilation and gas exchange function of the lungs as the result of endoscopic valvular bronchial blocking in patients with recurrent fibro-cavernous tuberculosis after lung resection". Medical alphabet 3, n.º 29 (17 de novembro de 2019): 8–15. http://dx.doi.org/10.33667/2078-5631-2019-3-29(404)-8-15.
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In the complex treatment of patients with tuberculosis with destruction of pulmonary tissue in the presence of drug-resistant pathogen in 10.2 % of cases it is necessary to resort to surgery in the form of resection or pulmonectomy. In the postoperative period, there are cases of progression of a specific process in the lungs with the formation of destruction. In such a situation, the optimal choice of treatment strategy is endoscopic valve bronchomalacia (ECB) with maximum preservation of functioning lung tissue. The aim of this work is to study the dynamics of ventilation and gas exchange function of the lungs in patients with acute pulmonary tissue destruction after surgery. The study revealed a change in the functional state of the lungs in 56 % of cases: negative in 39 % of patients and positive — in 17 %. The nature of the changes associated with the initial state of the bronchopulmonary apparatus and the characteristics of drug resistant. Deterioration of function is more often observed in a two-sided process and/or in the presence of two or more caverns. The initial state of the lung ventilation capacity and the presence of signs of restrictive disorders have the opposite effect on the functional outcome of bronchoblocation: at normal values of FEV1 and ESRD IS accompanied by more frequent broncho-obstructive disorders and deterioration of gas exchange rates than at their reduced values. The same paradoxical functional dependence of the dynamics can be traced in the volume «off» when drug resistant and its effectiveness.
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Mishra, Rashmi, Pavithra Reddy e Misbahuddin Khaja. "Fatal Cerebral Air Embolism: A Case Series and Literature Review". Case Reports in Critical Care 2016 (2016): 1–4. http://dx.doi.org/10.1155/2016/3425321.
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Cerebral air embolism (CAE) is an infrequently reported complication of routine medical procedures. We present two cases of CAE. The first patient was a 55-year-old male presenting with vomiting and loss of consciousness one day after his hemodialysis session. Physical exam was significant for hypotension and hypoxia with no focal neurologic deficits. Computed tomography (CT) scan of head showed gas in cerebral venous circulation. The patient did not undergo any procedures prior to presentation, and his last hemodialysis session was uneventful. Retrograde rise of venous air to the cerebral circulation was the likely mechanism for venous CAE. The second patient was a 46-year-old female presenting with fever, shortness of breath, and hematemesis. She was febrile, tachypneic, and tachycardic and required intubation and mechanical ventilation. An orogastric tube inserted drained 2500 mL of bright red blood. Flexible laryngoscopy and esophagogastroduodenoscopy were performed. She also underwent central venous catheter placement. CT scan of head performed the next day due to absent brain stem reflexes revealed intravascular air within cerebral arteries. A transthoracic echocardiogram with bubble study ruled out patent foramen ovale. The patient had a paradoxical CAE in the absence of a patent foramen ovale.
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Stanic, Vojkan, Tatjana Vulovic, Marjan Novakovic, Aleksandar Ristanovic, Davor Stamenovic, Vlado Cvijanovic, Nenad Stepic e Gordana Djordjevic. "Radical resection of giant chondrosarcoma of the anterior chest wall". Vojnosanitetski pregled 65, n.º 1 (2008): 64–68. http://dx.doi.org/10.2298/vsp0801064s.
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Background. Chondrosarcomas represent approximately 30% of primary malignant bone tumors, the most frequent of which is on anterior thoracic wall. Case report. We presented a case of 50-year-old man suffering from a slowgrowing, painless giant chondrosarcoma of the anterior chest wall. A wide resection was performed to excise the tumor including attached skin, right breast, ribs, sternum, soft tissues and parietal pleura. Mediastinum was not affected by the tumor. After resecting a 26 ? 20 ? 22 cm segment, the chest wall defect was reconstructed with a Marlex mesh and extensive latissimus dorsi myocutaneous flap pedicled on the right thoracodorsal vessels. Histopatology diagnosis was chondrosarcoma G 2?3. The mechanics of ventilation was not altered and respiratory function was normal from the immediate postoperative period. Three years after the operation postoperative results showed no local recurrence and excellent functional and aesthetic results were evident. Respiratory function remained unaltered. Conclusion. According to the results it can be concluded that the use of Marlex mash and myocutaneous flap is good method for stabilization of the chest wall and enough to avoid paradoxical respiratory movements in managing giant chondrosarcoma of the anterior chest wall.
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Bandyopadhyay, Raktim, Romy Biswas, Sharmistha Bhattacherjee, Sankar Prasad Kabiraj e lndrajit Gupta. "Anatomical variation of middle concha and its clinical correlates: a study among patients attending North Bengal Medical College". National Journal of Clinical Anatomy 04, n.º 02 (abril de 2015): 86–92. http://dx.doi.org/10.1055/s-0039-3401557.
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Abstract Background and aims: Lateral nasal wall of each nasal cavity provides the final common pathway of drainage of the muco-ciliary clearance of frontal, maxillary and anterior ethmoidal air cells. Anatomical variant like Concha Bullosa may obstruct the muco ciliary clearance thmugh osteomeatal complex and cause rhino sinusitis. The objectives were to find out the anatomical variation of middle concha and its clinical correlates with variation of middle concha. Methods: The present study was a descriptive, hospital based cross sectional study carried out in the outpatient departments of North Bengal Medical College & Hospital among 15 years and above patients. Coronal CT scan of paranasal sinus and orbit region was done. Data was collected with the help of semi structured predesigned and pretested questionnaire. Results: Of the 44 study patients, 15.9% had Concha Bullosa, 11.36% had paradoxical middle concha. Dimensions of right and left concha were also studied. 77.3%, 59.1% and 47.7% had sneezing, rhinorrhoea and headache respectively. Conclusion: The harmony of mucociliary clearance and obstruction free osteomeatal complex is the key factor for ventilation and drainage of maxillary, fmntal and anterior ethmoidal air cells.
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Misra, U. K., J. Kalita, M. Kumar, A. Tripathi e P. Mishra. "Complications of tuberculous meningitis and their effect on outcome in a tertiary care cohort". International Journal of Tuberculosis and Lung Disease 24, n.º 11 (1 de novembro de 2020): 1194–99. http://dx.doi.org/10.5588/ijtld.20.0036.
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BACKGROUND: To report the frequency and severity of complications, and their effect on the outcome of tuberculous meningitis (TBM).METHODS: In this retrospective cohort study, the following TBM complications were observed: status epilepticus (SE), hydrocephalus, paradoxical clinical worsening (PCW), hyponatremia, drug-induced hepatitis (DIH), infarction and mechanical ventilation (MV). These were recorded and correlated with stage of meningitis and outcome.RESULTS: A total of 144 patients with TBM (median age 26 years, range 12–75) were included. There were 76 (52.8%) females. The patients were in Stage I (n = 33), Stage II (n = 82) and Stage III (n = 29); 58 had definite TBM. Complications occurred in 128 (88.9%); complications included hydrocephalus (n = 58, 40.3%), hyponatremia (n = 70, 48.6%), infarction (n = 48, 33.3%), DIH (n = 42, 29.2%), SE (n = 16, 18.0%), MV (n = 43, 29.9%) and PCW (n = 24, 16.7%), with variable overlap. By 6 months, 33 patients had died. Death was related to PCW (P = 0.016), hyponatremia (P = 0.03), MV (P = 0.02), infarction (P = 0.03) and the number of complications. Except PCW, most complications occurred during the first month.CONCLUSIONS: In TBM, complications occurred in 128 (88.9%) patients, mainly in the early stages, with variable overlap. Infarction, PCW, hyponatremia and MV were predictive of poor outcome.
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Gozal, D., R. Arens, K. J. Omlin, S. L. Ward e T. G. Keens. "Absent peripheral chemosensitivity in Prader-Willi syndrome". Journal of Applied Physiology 77, n.º 5 (1 de novembro de 1994): 2231–36. http://dx.doi.org/10.1152/jappl.1994.77.5.2231.
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Abnormalities in ventilatory control during wakefulness and sleep have been observed in patients with Prader-Willi syndrome (PWS). The role of peripheral chemoreceptors in the pathophysiology of abnormal ventilatory responses in PWS is unknown. We studied peripheral chemoreceptor function during wakefulness in 17 genetically confirmed PWS patients [age 27.0 +/- 2.5 (SE) yr; 7 males, 10 females; body mass index 31.1 +/- 1.4 kg/m2] and compared their responses with 17 control subjects matched for age, sex, and body mass index. All PWS and control subjects had normal resting end-tidal PCO2 and arterial O2 saturation while awake. Peripheral chemoreceptor function was assessed by the ventilatory responses to 100% O2 breathing, five tidal breaths of 100% N2, and vital capacity breaths of 15% CO2 in O2. Control subjects decreased minute ventilation (VE) by 15.5 +/- 3.6% during hyperoxia. However, PWS patients increased VE by 17.6 +/- 3.3%, indicating a paradoxical response to hyperoxia (P < 0.00001). After CO2 vital capacity breaths, PWS patients showed no significant change and control subjects showed a marked increase (P < 0.0001) in VE. During N2 breathing, again PWS patients showed no change and control subjects exhibited a marked increase (P < 0.00005) in VE. We conclude that PWS patients have absent peripheral chemoreceptor ventilatory responses. We speculate that the lack of ventilatory responses is due to primary peripheral chemoreceptor dysfunction and/or defective afferent pathways to central controllers.
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McKenzie, David K., Jane E. Butler e Simon C. Gandevia. "Respiratory muscle function and activation in chronic obstructive pulmonary disease". Journal of Applied Physiology 107, n.º 2 (agosto de 2009): 621–29. http://dx.doi.org/10.1152/japplphysiol.00163.2009.
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Inspiratory muscles are uniquely adapted for endurance, but their function is compromised in chronic obstructive pulmonary disease (COPD) due to increased loads, reduced mechanical advantage, and increased ventilatory requirements. The hyperinflation of COPD reduces the flow and pressure-generating capacity of the diaphragm. This is compensated by a threefold increase in neural drive, adaptations of the chest wall and diaphragm shape to accommodate the increased volume, and adaptations of muscle fibers to preserve strength and increase endurance. Paradoxical indrawing of the lower costal margin during inspiration in severe COPD (Hoover's sign) correlates with high inspiratory drive and severe airflow obstruction rather than contraction of radially oriented diaphragm fibers. The inspiratory muscles remain highly resistant to fatigue in patients with COPD, and the ultimate development of ventilatory failure is associated with insufficient central drive. Sleep is associated with reduced respiratory drive and impairments of lung and chest wall function, which are exaggerated in COPD patients. Profound hypoxemia and hypercapnia can occur in rapid eye movement sleep and contribute to the development of cor pulmonale. Inspiratory muscles adapt to chronic loading with an increased proportion of slow, fatigue-resistant fiber types, increased oxidative capacity, and reduced fiber cross-sectional area, but the capacity of the diaphragm to increase ventilation in exercise is compromised in COPD. In COPD, neural drive to the diaphragm increases to near maximal levels in exercise, but it does not develop peripheral muscle fatigue. The improvement in exercise capacity and dyspnea following lung volume reduction surgery is associated with a substantial reduction in neural drive to the inspiratory muscles.
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Schafer, T., D. Schafer e M. E. Schlafke. "Breathing, transcutaneous blood gases, and CO2 response in SIDS siblings and control infants during sleep". Journal of Applied Physiology 74, n.º 1 (1 de janeiro de 1993): 88–102. http://dx.doi.org/10.1152/jappl.1993.74.1.88.
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Age-related changes of 20 variables describing breathing patterns, transcutaneous blood gases, and estimated CO2 response during sleep were examined in a cross-sectional study of 30 healthy control infants and 150 healthy siblings of sudden infant death syndrome victims within the first 18 mo of life. Whole-night measurements were performed using noninvasive respiratory induction plethysmography and transcutaneous blood gas electrodes. Each candidate for the study was extensively screened and found to be healthy. Mean transcutaneous PCO2 (PtcCO2, median 40.3 Torr) and maximum PtcCO2 (median 44.8 Torr), as well as the estimated ventilatory response to inhalation of 2% CO2 in air during regular breathing, causing a 20–36% increase of ventilation per Torr PtcCO2, were not related to postnatal age. In contrast, paradoxical breathing decreased from 49.5 to 0% of total sleep time (TST), periodic breathing from 5.5 to 0% TST, and respiratory rate during regular breathing from 40 to 22 breaths/min; the portion of regular breathing increased from 32 to 55% TST and mean and minimum transcutaneous PO2 from 65.4 and 47 to 69.7 and 52 Torr with increasing stability. The largest changes occurred in the first 6 mo of life. Maximum apnea duration (9.5 s, maximum 16 s), mean apnea duration (3.74 s, breathing pauses > or = 2 s), and time spent apneic per hour of irregular breathing (199 s/h) were not related to age. The comparison of data from siblings and controls showed similarities in the above-mentioned variables. No significant differences were found among the groups. Also a comparison of 30 pairs of siblings and controls, matched for age, gender, birth, and actual body weight, did not show significant differences. The present study extends the knowledge of development of breathing control beyond the first 6 mo of life.
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Ramesh Babu, G., G. Ravi Kumar e V. Krishna Chaitanya. "Correlation of anatomical variations in chronic sinusitis with diagnostic nasal endoscopy and CT scan of paranasal sinuses: an observational study". International Journal of Otorhinolaryngology and Head and Neck Surgery 5, n.º 1 (25 de dezembro de 2018): 41. http://dx.doi.org/10.18203/issn.2454-5929.ijohns20184723.
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<p class="abstract"><strong>Background:</strong> Drainage and ventilation of paranasal sinuses are important for normal function which depends on effective mucociliary clearance. In present study we tried to emphasize variations in lateral wall of nose and clinical features leading to nose and paranasal sinus disease using diagnostic nasal endoscopy and variations in CT scan of paranasal sinuses. The objectives of the study are to observe various anatomical variations in nose and paranasal sinuses and their clinical presentation using diagnostic nasal endoscopy and CT scan of paranasal sinuses and to compare various anatomical variations in nose and paranasal sinuses.</p><p class="abstract"><strong>Methods: </strong>Present study included 54 patients presenting in Department of ENT, Head and Neck Surgery, during February 2015 to February 2017. </p><p class="abstract"><strong>Results:</strong> Diagnostic nasal endoscopy findings reveal that most common finding was polypoidal changes in nasal mucosa in 36 (66.67%) of patients, followed by mucopurulent discharge in 26 (48.14%), postnasal discharge in 20(37.03%) and 4 (7.40%) patients showed prominent agger nasi cell. CT scan of paranasal sinuses revealed multiple sinus involvement in 41 (75.92%) of patients with partial involvement of sinuses. Complete sinus opacification with pan sinusitis was observed in 9 (16.67%), blockade at osteomeatal complex was observed in 46 (85.18%), paradoxical middle turbinate was observed in 5 (9.25%), Concha bullosa was observed in 12 (22.23%) of patients.</p><p class="abstract"><strong>Conclusions:</strong> Each variation have an anatomic and surgical significance, hence each and every case should be individually studied in detail before undergoing functional endoscopic sinus surgery to maximize patient benefit and to prevent unnecessary complications. Diagnostic nasal endoscopic examination is clinical guide to evaluate disease.</p>
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Reignier, Jean, Mondher Ben Ameur e Claude Ecoffey. "Spontaneous Ventilation with Halothane in Children". Anesthesiology 83, n.º 4 (1 de outubro de 1995): 674–78. http://dx.doi.org/10.1097/00000542-199510000-00005.
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Background It has been reported that, in children breathing spontaneously via an endotracheal tube, halothane depresses ventilation with paradoxic inspiratory movement. Endotracheal tubes have a higher airflow resistance than do laryngeal mask airways (LMAs). Therefore, the aim of this study was to compare spontaneous ventilation via the LMA with that via the endotracheal tube in children anesthetized with halothane. Methods The authors studied two groups of 6-24-month-old children with no cardiorespiratory and neurologic disorders, undergoing elective minor surgery with halothane anesthesia: one group breathing via LMA (n = 10) and one group breathing via endotracheal tube (n = 10). They measured tidal volume, respiratory rate, minute ventilation, and end-tidal CO2. They assessed paradoxic inspiratory movement using amplitude index and phase delay index. Results Age and weight were similar in both groups. Mean +/- SD tidal volume (7.5 +/- 1.9 ml/kg in the LMA group vs. 5.3 +/- 1.1 ml/kg in the endotracheal tube group; P < 0.05) and minute ventilation (325 +/- 105 ml.min-1.kg-1 in the LMA group vs. 246 +/- 38 ml.min-1.kg-1 in the endotracheal tube group; P < 0.05) were lower in the endotracheal tube group. The phase delay index (18 +/- 11% in the LMA group vs. 41 +/- 19% in the endotracheal tube group; P < 0.05) and the amplitude index (25 +/- 43% in the LMA group vs. 74 +/- 72% in the endotracheal tube group; P < 0.05) were significantly smaller with the LMA than with the endotracheal tube. Conclusions In 6-24-month-old children anesthetized with halothane, paradoxic inspiratory movement is less when breathing through an LMA than through an endotracheal tube.
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Wang, Ting, Christine Gross, Ankit A. Desai, Evgeny Zemskov, Xiaomin Wu, Alexander N. Garcia, Jeffrey R. Jacobson, Jason X. J. Yuan, Joe G. N. Garcia e Stephen M. Black. "Endothelial cell signaling and ventilator-induced lung injury: molecular mechanisms, genomic analyses, and therapeutic targets". American Journal of Physiology-Lung Cellular and Molecular Physiology 312, n.º 4 (1 de abril de 2017): L452—L476. http://dx.doi.org/10.1152/ajplung.00231.2016.
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Mechanical ventilation is a life-saving intervention in critically ill patients with respiratory failure due to acute respiratory distress syndrome (ARDS). Paradoxically, mechanical ventilation also creates excessive mechanical stress that directly augments lung injury, a syndrome known as ventilator-induced lung injury (VILI). The pathobiology of VILI and ARDS shares many inflammatory features including increases in lung vascular permeability due to loss of endothelial cell barrier integrity resulting in alveolar flooding. While there have been advances in the understanding of certain elements of VILI and ARDS pathobiology, such as defining the importance of lung inflammatory leukocyte infiltration and highly induced cytokine expression, a deep understanding of the initiating and regulatory pathways involved in these inflammatory responses remains poorly understood. Prevailing evidence indicates that loss of endothelial barrier function plays a primary role in the development of VILI and ARDS. Thus this review will focus on the latest knowledge related to 1) the key role of the endothelium in the pathogenesis of VILI; 2) the transcription factors that relay the effects of excessive mechanical stress in the endothelium; 3) the mechanical stress-induced posttranslational modifications that influence key signaling pathways involved in VILI responses in the endothelium; 4) the genetic and epigenetic regulation of key target genes in the endothelium that are involved in VILI responses; and 5) the need for novel therapeutic strategies for VILI that can preserve endothelial barrier function.
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Peyton, Philip J., Gavin J. B. Robinson e Bruce Thompson. "Ventilation-perfusion inhomogeneity increases gas uptake: theoretical modeling of gas exchange". Journal of Applied Physiology 91, n.º 1 (1 de julho de 2001): 3–9. http://dx.doi.org/10.1152/jappl.2001.91.1.3.
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Ventilation-perfusion (V˙a/Q˙) inhomogeneity was modeled to measure its effect on gas exchange in the presence of inspired mixtures of two soluble gases using a two-compartment computer model. Theoretical studies involving a mixture of hypothetical gases with equal solubility in blood showed that the effect of increasing inhomogeneity of distributions of either ventilation or blood flow is to paradoxically increase uptake of the gas with the lowest overall uptake in relation to its inspired concentration. This phenomenon is explained by the concentrating effects that uptake of soluble gases exert on each other in low V˙a/Q˙ compartments. Repeating this analysis for inspired mixtures of 30% O2and 70% nitrous oxide (N2O) confirmed that, during “steady-state” N2O anesthesia, uptake of N2O is predicted to paradoxically increase in the presence of worsening V˙a/Q˙ inhomogeneity.
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Peyton, Philip J., Gavin J. B. Robinson e Bruce Thompson. "Ventilation-perfusion inhomogeneity increases gas uptake in anesthesia: computer modeling of gas exchange". Journal of Applied Physiology 91, n.º 1 (1 de julho de 2001): 10–16. http://dx.doi.org/10.1152/jappl.2001.91.1.10.
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Ventilation-perfusion (V˙a/Q˙) inhomogeneity was modeled to measure its effect on overall gas exchange during maintenance-phase N2O anesthesia with an inspired O2 concentration of 30%. A multialveolar compartment computer model was used based on physiological log normal distributions of V˙a/Q˙ inhomogeneity. Increasing the log standard deviation of the distribution of perfusion from 0 to 1.75 paradoxically increased O2 uptake (V˙o 2) where a low mixed venous partial pressure of N2O [high N2O uptake (V˙n 2 o)] was specified. With rising mixed venous partial pressure of N2O, a threshold was observed where V˙o 2 began to fall, whereas V˙n 2 o began to rise with increasing V˙a/Q˙ inhomogeneity. This phenomenon is a magnification of the concentrating effects thatV˙o 2 andV˙n 2 o have on each other in low V˙a/Q˙ compartments. During “steady-state” N2O anesthesia,V˙n 2 o is predicted to paradoxically increase in the presence of worseningV˙a/Q˙ inhomogeneity.
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Zhuang, J., T. Droma, S. Sun, C. Janes, R. E. McCullough, R. G. McCullough, A. Cymerman, S. Y. Huang, J. T. Reeves e L. G. Moore. "Hypoxic ventilatory responsiveness in Tibetan compared with Han residents of 3,658 m". Journal of Applied Physiology 74, n.º 1 (1 de janeiro de 1993): 303–11. http://dx.doi.org/10.1152/jappl.1993.74.1.303.
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Lifelong high-altitude residents of North and South America acquire blunted hypoxic ventilatory responses and exhibit decreased ventilation compared with acclimatized newcomers. The ventilatory characteristics of Himalayan high-altitude residents are of interest in the light of their reportedly lower hemoglobin levels and legendary exercise performance. Until recently, Sherpas have been the only Himalayan population available for study. To determine whether Tibetans exhibited levels of ventilation and hypoxic ventilatory drives that were as great as acclimatized newcomers, we compared 27 lifelong Tibetan residents of Lhasa, Tibet, China (3,658 m) with 30 acclimatized Han ("Chinese") newcomers matched for age, body size, and extent of exercise training. During room air breathing, minute ventilation was greater in the Tibetan than in the Han young men because of an increased respiratory frequency, but arterial O2 saturation and end-tidal PCO2 did not differ, indicating similar levels of effective alveolar ventilation. The Tibetan subjects had higher hypoxic ventilatory response shape parameter A values and hypercapnic ventilatory responsiveness than the Han subjects. Among the Han subjects, duration of high-altitude residence correlated with the degree of blunting of the hypoxic ventilatory drive. Paradoxically, hyperoxia (inspired O2 fraction 0.70) increased minute ventilation and decreased end-tidal PCO2 in the Tibetan but not in the Han men. We concluded that lifelong Tibetan residents of high altitude neither hypoventilated nor exhibited blunted hypoxic ventilatory responses compared with acclimatized Han newcomers, suggesting that the effects of lifelong high-altitude residence on ventilation and ventilatory response to hypoxia differ in Tibetan compared with other high-altitude populations. Lifelong high-altitude residents of North and South America acquire blunted hypoxic ventilatory responses and exhibit decreased ventilation compared with acclimatized newcomers. The ventilatory characteristics of Himalayan high-altitude residents are of interest in the light of their reportedly lower hemoglobin levels and legendary exercise performance. Until recently, Sherpas have been the only Himalayan population available for study. To determine whether Tibetans exhibited levels of ventilation and hypoxic ventilatory drives that were as great as acclimatized newcomers, we compared 27 lifelong Tibetan residents of Lhasa, Tibet, China (3,658 m) with 30 acclimatized Han ("Chinese") newcomers matched for age, body size, and extent of exercise training. During room air breathing, minute ventilation was greater in the Tibetan than in the Han young men because of an increased respiratory frequency, but arterial O2 saturation and end-tidal PCO2 did not differ, indicating similar levels of effective alveolar ventilation. The Tibetan subjects had higher hypoxic ventilatory response shape parameter A values and hypercapnic ventilatory responsiveness than the Han subjects. Among the Han subjects, duration of high-altitude residence correlated with the degree of blunting of the hypoxic ventilatory drive. Paradoxically, hyperoxia (inspired O2 fraction 0.70) increased minute ventilation and decreased end-tidal PCO2 in the Tibetan but not in the Han men. We concluded that lifelong Tibetan residents of high altitude neither hypoventilated nor exhibited blunted hypoxic ventilatory responses compared with acclimatized Han newcomers, suggesting that the effects of lifelong high-altitude residence on ventilation and ventilatory response to hypoxia differ in Tibetan compared with other high-altitude populations. Lifelong high-altitude residents of North and South America acquire blunted hypoxic ventilatory responses and exhibit decreased ventilation compared with acclimatized newcomers. The ventilatory characteristics of Himalayan high-altitude residents are of interest in the light of their reportedly lower hemoglobin levels and legendary exercise performance. Until recently, Sherpas have been the only Himalayan population available for study. To determine whether Tibetans exhibited levels of ventilation and hypoxic ventilatory drives that were as great as acclimatized newcomers, we compared 27 lifelong Tibetan residents of Lhasa, Tibet, China (3,658 m) with 30 acclimatized Han ("Chinese") newcomers matched for age, body size, and extent of exercise training. During room air breathing, minute ventilation was greater in the Tibetan than in the Han young men because of an increased respiratory frequency, but arterial O2 saturation and end-tidal PCO2 did not differ, indicating similar levels of effective alveolar ventilation. The Tibetan subjects had higher hypoxic ventilatory response shape parameter A values and hypercapnic ventilatory responsiveness than the Han subjects. Among the Han subjects, duration of high-altitude residence correlated with the degree of blunting of the hypoxic ventilatory drive. Paradoxically, hyperoxia (inspired O2 fraction 0.70) increased minute ventilation and decreased end-tidal PCO2 in the Tibetan but not in the Han men. We concluded that lifelong Tibetan residents of high altitude neither hypoventilated nor exhibited blunted hypoxic ventilatory responses compared with acclimatized Han newcomers, suggesting that the effects of lifelong high-altitude residence on ventilation and ventilatory response to hypoxia differ in Tibetan compared with other high-altitude populations. Lifelong high-altitude residents of North and South America acquire blunted hypoxic ventilatory responses and exhibit decreased ventilation compared with acclimatized newcomers. The ventilatory characteristics of Himalayan high-altitude residents are of interest in the light of their reportedly lower hemoglobin levels and legendary exercise performance. Until recently, Sherpas have been the only Himalayan population available for study. To determine whether Tibetans exhibited levels of ventilation and hypoxic ventilatory drives that were as great as acclimatized newcomers, we compared 27 lifelong Tibetan residents of Lhasa, Tibet, China (3,658 m) with 30 acclimatized Han ("Chinese") newcomers matched for age, body size, and extent of exercise training. During room air breathing, minute ventilation was greater in the Tibetan than in the Han young men because of an increased respiratory frequency, but arterial O2 saturation and end-tidal PCO2 did not differ, indicating similar levels of effective alveolar ventilation. The Tibetan subjects had higher hypoxic ventilatory response shape parameter A values and hypercapnic ventilatory responsiveness than the Han subjects. Among the Han subjects, duration of high-altitude residence correlated with the degree of blunting of the hypoxic ventilatory drive. Paradoxically, hyperoxia (inspired O2 fraction 0.70) increased minute ventilation and decreased end-tidal PCO2 in the Tibetan but not in the Han men. We concluded that lifelong Tibetan residents of high altitude neither hypoventilated nor exhibited blunted hypoxic ventilatory responses compared with acclimatized Han newcomers, suggesting that the effects of lifelong high-altitude residence on ventilation and ventilatory response to hypoxia differ in Tibetan compared with other high-altitude populations.
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Albert, Sandeep, Viswanath Jayashankar e Mohamad Gouse. "A Paradoxical Triad: Scapulothoracic Dissociation with Clavicle and Humeral Shaft Fractures". Case Reports in Emergency Medicine 2014 (2014): 1–3. http://dx.doi.org/10.1155/2014/689157.
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Scapulothoracic dissociation involves varying degree of discontinuity of the upper extremity from its truncal attachment. An eighteen-year-old male presented to the accident and emergency department following a motor vehicle accident where he was hit by a four wheeler while riding a two wheeler. He had tenderness and deformity over the left clavicle and the left humerus. He was unable to perform active wrist and finger dorsiflexion. A CT subsequently revealed a grade 2 splenic laceration. The splenic laceration was treated conservatively. As his general condition improved, he was gradually weaned off the ventilator and his left upper limb neurology was reassessed. He had isolated radial nerve palsy with an otherwise intact brachial plexus. He underwent internal fixation of the clavicle and the humerus. At 4 months after injury the EMG/NCV report showed signs of renervation of the radial nerve, and the fracture progressed to an uneventful union. This prior unreported triad of scapulothoracic dissociation with ipsilateral clavicular and humeral fractures may represent a parody. An apparent increase in the severity of skeletal injury was associated with a paradoxical decrease in the severity of neurovascular injury. We report this case to create awareness among orthopedic surgeons and emergency physicians about the clinical presentation of such injuries.
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Edwards, Miles J. "Opioids and Benzodiazepines Appear Paradoxically to Delay Inevitable Death after Ventilator Withdrawal". Journal of Palliative Care 21, n.º 4 (dezembro de 2005): 299–302. http://dx.doi.org/10.1177/082585970502100410.
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Kong, Xiangrui, Yuexia Sun, Louise B. Weschler e Jan Sundell. "Dampness problems in Tianjin dwellings: A cross-sectional study of associations with building characteristics and lifestyles". Indoor and Built Environment 28, n.º 1 (7 de fevereiro de 2018): 132–44. http://dx.doi.org/10.1177/1420326x18756169.
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This study investigated the association of building characteristics and occupant behaviours with building dampness indicators. Data were from a cross-sectional study in urban Tianjin and rural Cangzhou, China, from 2013 to 2014. We studied two fundamental types of Chinese dwellings: bungalows typical of rural locales and apartments in low- and high-rise buildings typical of urban settings. Occupants of bungalows reported more dampness indicators than apartment dwellers. Risk factors for one or more dampness indicators included natural ventilation without fans, older dwellings and coal stove or Kang heating system (a brick bed installed in the bedroom for heating and sleeping). All these factors were typical of bungalows, which generally used older building technologies including non-insulated external walls, wooden frame windows, electric fans for cooling and no exhaust fan ventilation. Occupant behaviours that decreased the risk for dampness indicators included frequent window opening and daily cleaning, regardless of the type of dwelling. Indoor dampness was highly correlated with mouldy and humid odour, and paradoxically (although not a new finding) with the perception of air dryness.
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Karpishchenko, S. A., E. V. Bolozneva, A. Yu Golubev e E. E. Kozyreva. "Influence of shape of middle turbinate on development of recurrent rhinosinusitis". Russian Otorhinolaryngology 20, n.º 3 (2021): 108–14. http://dx.doi.org/10.18692/1810-4800-2021-3-108-114.
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In the presence of a paradoxically curved middle nasal turbinate, treatment tactics may be different. To achieve the best effect in the treatment of chronic rhinosinusitis, in some cases, a complete resection of the middle nasal turbinate is performed. However, in this group of patients in the postoperative period, complaints may appear from the quality of nasal breathing, which is associated with the development of paradoxically difficult breathing, when with sufficient passage of the air jet, the patient complains of difficulty in nasal breathing. Also, these patients are characterized by a decrease in the sense of smell. It is important that the absence of the middle nasal turbinate during repeated surgical interventions deprives the surgeon of an important anatomical landmark. We want to share a clinical example in which we received a positive outcome of surgical treatment in a patient with chronic left-sided rhinosinusitis in the presence of a paradoxically curved middle nasal turbinate and a slightly deviated nasal septum. In order to restore ventilation of the anterior group of the paranasal sinuses, the lateral part of the paradoxically curved middle nasal turbinate was removed with its preservation and expansion of the natural anastomosis of the maxillary sinus. In the postoperative period, the patient noted a significant improvement in her condition and did not make any previous complaints. This clinical case demonstrates that the middle nasal turbinate plays an important role in the functioning of the nasal cavity, in particular the osteomeatal complex, and in various anatomical variants can disrupt its work, both in combination with other structural features of the lateral nasal wall, and in isolation. In this connection, during the surgical treatment, a sparing, organ-preserving technique was chosen in order to preserve the functions of the middle turbinate, which in the postoperative period led to the achievement of a stable positive result.
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Perazzolo, Laura, e Claudio Marengo. "Unexpected complications of pulmonary edema". Clinical Management Issues 4, n.º 3S (13 de outubro de 2015): 25–30. http://dx.doi.org/10.7175/cmi.v4i3s.1150.
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The article illustrates the case report of a patient, an elderly woman, admitted in the Emergency Department (ED) with acute pulmonary edema, which was quickly solved through a well-timed application of the therapeutic protocols. At first, the course of the treatment was positive, but some complications developed because of the long stay in the hospital, specifically a decubitus ulcer; this condition quickly evolved regardless of the proper treatment, and caused a progressive fall of the general clinical status of the patient. Within the ER, some state-of-the-art clinical apparatus (protocols, unintrusive ventilation) are available for even the treatment of the worst conditions. ED overcrowding – with full occupancy of beds and long waits of patients – is related to greater risk of poor outcomes. One of the risks is to expose the patient to serious complications, that are note related to the reason of admission in hospital, but, paradoxically, are caused by the prolonged hospitalization in ED.
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Hurley, James C. "Paradoxical ventilator associated pneumonia incidences among selective digestive decontamination studies versus other studies of mechanically ventilated patients: benchmarking the evidence base". Critical Care 15, n.º 1 (2011): R7. http://dx.doi.org/10.1186/cc9406.
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Hurley, J. C. "Paradoxical Acinetobacter-associated ventilator-associated pneumonia incidence rates within prevention studies using respiratory tract applications of topical polymyxin: benchmarking the evidence base". Journal of Hospital Infection 100, n.º 1 (setembro de 2018): 105–13. http://dx.doi.org/10.1016/j.jhin.2018.04.005.
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Kazimierczak, Anna, Paweł Krzesiński, Krystian Krzyżanowski e Grzegorz Gielerak. "Sleep-Disordered Breathing in Patients with Heart Failure: New Trends in Therapy". BioMed Research International 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/459613.
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Heart failure (HF) is a growing health problem which paradoxically results from the advances in the treatment of etiologically related diseases (especially coronary artery disease). HF is commonly accompanied by sleep-disordered breathing (SDB), which may directly exacerbate the clinical manifestations of cardiovascular disease and confers a poorer prognosis. Obstructive sleep apnoea predominates in mild forms while central sleep apnoea in more severe forms of heart failure. Identification of SDB in patients with HF is important, as its effective treatment may result in notable clinical benefits to the patients. Continuous positive airway pressure (CPAP) is the gold standard in the management of SDB. The treatments for central breathing disorders include CPAP, bilevel positive airway pressure (BPAP), and adaptive servoventilation (ASV), with the latter being the most modern method of treatment for the Cheyne-Stokes respiration and involving ventilation support with a variable synchronisation dependent on changes in airflow through the respiratory tract and on the patient’s respiratory rate. ASV exerts the most favourable effect on long-term prognosis. In this paper, we review the current state of knowledge on the diagnosis and treatment of SDB with a particular emphasis on the latest methods of treatment.
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Mulkey, Daniel K., Richard A. Henderson, Robert W. Putnam e Jay B. Dean. "Hyperbaric oxygen and chemical oxidants stimulate CO2/H+-sensitive neurons in rat brain stem slices". Journal of Applied Physiology 95, n.º 3 (setembro de 2003): 910–21. http://dx.doi.org/10.1152/japplphysiol.00864.2002.
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Hyperoxia, a model of oxidative stress, can disrupt brain stem function, presumably by an increase in O2 free radicals. Breathing hyperbaric oxygen (HBO2) initially causes hyperoxic hyperventilation, whereas extended exposure to HBO2 disrupts cardiorespiratory control. Presently, it is unknown how hyperoxia affects brain stem neurons. We have tested the hypothesis that hyperoxia increases excitability of neurons of the solitary complex neurons, which is an important region for cardiorespiratory control and central CO2/H+ chemoreception. Intracellular recordings were made in rat medullary slices during exposure to 2-3 atm of HBO2, HBO2 plus antioxidant (Trolox C), and chemical oxidants ( N-chlorosuccinimide, chloramine-T). HBO2 increased input resistance and stimulated firing rate in 38% of neurons; both effects of HBO2 were blocked by antioxidant and mimicked by chemical oxidants. Hypercapnia stimulated 32 of 60 (53%) neurons. Remarkably, these CO2/H+-chemosensitive neurons were preferentially sensitive to HBO2; 90% of neurons sensitive to HBO2 and/or chemical oxidants were also CO2/H+ chemosensitive. Conversely, only 19% of HBO2-insensitive neurons were CO2/H+ chemosensitive. We conclude that hyperoxia decreases membrane conductance and stimulates firing of putative central CO2/H+-chemoreceptor neurons by an O2 free radical mechanism. These findings may explain why hyperoxia, paradoxically, stimulates ventilation.
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Zubieta-Calleja, Gustavo, e Natalia Zubieta-DeUrioste. "The Oxygen Transport Triad in High-Altitude Pulmonary Edema: A Perspective from the High Andes". International Journal of Environmental Research and Public Health 18, n.º 14 (17 de julho de 2021): 7619. http://dx.doi.org/10.3390/ijerph18147619.
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Acute high-altitude illnesses are of great concern for physicians and people traveling to high altitude. Our recent article “Acute Mountain Sickness, High-Altitude Pulmonary Edema and High-Altitude Cerebral Edema, a View from the High Andes” was questioned by some sea-level high-altitude experts. As a result of this, we answer some observations and further explain our opinion on these diseases. High-Altitude Pulmonary Edema (HAPE) can be better understood through the Oxygen Transport Triad, which involves the pneumo-dynamic pump (ventilation), the hemo-dynamic pump (heart and circulation), and hemoglobin. The two pumps are the first physiologic response upon initial exposure to hypobaric hypoxia. Hemoglobin is the balancing energy-saving time-evolving equilibrating factor. The acid-base balance must be adequately interpreted using the high-altitude Van Slyke correction factors. Pulse-oximetry measurements during breath-holding at high altitude allow for the evaluation of high altitude diseases. The Tolerance to Hypoxia Formula shows that, paradoxically, the higher the altitude, the more tolerance to hypoxia. In order to survive, all organisms adapt physiologically and optimally to the high-altitude environment, and there cannot be any “loss of adaptation”. A favorable evolution in HAPE and pulmonary hypertension can result from the oxygen treatment along with other measures.
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Bissell, Brittany D., e Breanne Mefford. "Pathophysiology of Volume Administration in Septic Shock and the Role of the Clinical Pharmacist". Annals of Pharmacotherapy 54, n.º 4 (6 de novembro de 2019): 388–96. http://dx.doi.org/10.1177/1060028019887160.
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Objective: To review physiological rationale and evidence base surrounding fluid harm to prepare the clinical pharmacist for accountability regarding volume-related outcomes. Data Sources: A PubMed/MEDLINE search was conducted using the following terms: (fluid therapy) AND [(critical care) OR (sepsis)] from 1966 to August 2019 published in English. Study Selection and Data Extraction: A total of 3364 citations were reviewed with only relevant clinical data extracted. Data Synthesis: Although early fluid resuscitation may be a necessary component to decrease mortality in the majority of patients with septic shock admitted to the intensive care unit (ICU), the benefit of continued administration after the first 24 hours is uncertain. Paradoxically, a positive fluid balance secondary to intravenous fluid receipt has been associated with diverse and perpetuating detriment on a multitude of organ systems after the first 24 hours of ICU stay. Continued clinical harm has been demonstrated on patient outcomes such as rates of mortality and length of stay. Despite the growing body of evidence supporting the potential adverse aspects of positive fluid balance, fluid overload remains common during critical care admission. Conclusion: Physiological concerns to overly zealous fluid administration and subsequent volume overload are vast. Relevance to Patient Care and Clinical Practice: Optimization of fluid balance in critically ill patients with sepsis is primed for clinical pharmacy intervention. Critical care pharmacists have the potential to improve patient care by optimizing fluid pharmacotherapy while potentially reducing adverse events, days on mechanical ventilation, and length of ICU stay.