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Journal articles on the topic 'LR parsers'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Slivnik, Bostjan. "LL conflict resolution using the embedded left LR parser." Computer Science and Information Systems 9, no. 3 (2012): 1105–24. http://dx.doi.org/10.2298/csis111216023s.

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A method for resolving LL(k) conflicts using small LR(k) parsers (called embedded left LR(k) parsers) is described. An embedded left LR(k) parser is capable of (a) producing the prefix of the left parse of the input string and (b) stopping not on the end-of-file marker but on any string from the set of lookahead strings fixed at the parser generation time. The conditions regarding the termination of the embedded left LR(k) parser if used within LL(k) (and similar) parsers are defined and examined in-depth. It is proved that an LL(k) parser augmented with a set of embedded left LR(k) parsers can parse any deterministic context-free grammar in the same asymptotic time as LR(k) parser. As the embedded left LR(k) parser produces the prefix of the left parse, the LL(k) parser augmented with embedded left LR(k) parsers still produces the left parse and the compiler writer does not need to bother with different parsing strategies during the compiler implementation.

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2

Soisalon-Soininen, Eljas, and Jorma Tarhio. "Looping LR parsers." Information Processing Letters 26, no. 5 (January 1988): 251–53. http://dx.doi.org/10.1016/0020-0190(88)90149-4.

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3

KIPPS, JAMES R. "ADVANCED PARSER-GENERATION TECHNOLOGY FOR AI LANGUAGE APPLICATIONS." International Journal on Artificial Intelligence Tools 01, no. 04 (December 1992): 545–61. http://dx.doi.org/10.1142/s0218213092000053.

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A side effect of AI research is the development of programming languages as vehicles for experimentation and demonstration of concepts. These AI languages generally require some form of parser front end, which can be nontrivial to build. Parser generators can ease the task of language development, but commonly available generators use parsing technologies that severely constrain the level of syntactic sophistication, such as allowing at most one symbol of look ahead. Further, these generators are most often targeted for C and Ada applications; parser generators for LISP applications are not widely available. The RAND Advanced Compiler Kit (RACK) is a parser generator for generalized LR parsing and is suitable for AI applications. RACK parsers are unique in their ability to recognize non-LR(k) languages, as well as LR(k) languages for k > 1. RACK is implemented in C and is upwardly compatible with YACC, a widely used parser generator for C applications. RACK generates parsers that interface with C or Common Lisp. RACK also includes features such as arbitrary look-ahead, multiple start symbols, a scanner generator, and a grammar interpreter. In this paper, I describe RACK, its parsing technology, and significant features; I also report performance results comparing RACK to YACC.

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4

Machanick, P. "Are LR parsers too powerful?" ACM SIGPLAN Notices 21, no. 6 (June 1986): 35–40. http://dx.doi.org/10.1145/14937.14940.

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5

Pottier, François, and Yann Régis-Gianas. "Towards Efficient, Typed LR Parsers." Electronic Notes in Theoretical Computer Science 148, no. 2 (March 2006): 155–80. http://dx.doi.org/10.1016/j.entcs.2005.11.044.

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6

Horspool, R. Nigel. "Incremental generation of LR parsers." Computer Languages 15, no. 4 (January 1990): 205–23. http://dx.doi.org/10.1016/0096-0551(90)90021-g.

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7

Kanze, J. "Handling ambiguous tokens in LR-Parsers." ACM SIGPLAN Notices 24, no. 6 (June 1989): 49–54. http://dx.doi.org/10.1145/71052.71059.

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8

Pezaris, S. D. "Shift-reduce conflicts in LR parsers." ACM SIGPLAN Notices 24, no. 11 (November 1989): 94–95. http://dx.doi.org/10.1145/71605.71611.

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9

Corchuelo, Rafael, José A. Pérez,, Antonio Ruiz, and Miguel Toro. "Repairing syntax errors in LR parsers." ACM Transactions on Programming Languages and Systems 24, no. 6 (November 2002): 698–710. http://dx.doi.org/10.1145/586088.586092.

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10

Ancona, Massimo, Claudia Fassino, and Vittoria Gianuzzi. "Optimization of LR(k) “Reduced parsers”." Information Processing Letters 41, no. 1 (January 1992): 13–20. http://dx.doi.org/10.1016/0020-0190(92)90074-6.

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11

Yeh, Dashing, and Uwe Kastens. "Automatic construction of incremental LR(1)—parsers." ACM SIGPLAN Notices 23, no. 3 (March 1988): 33–42. http://dx.doi.org/10.1145/43895.43899.

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12

Sperber, Michael, and Peter Thiemann. "Generation of LR parsers by partial evaluation." ACM Transactions on Programming Languages and Systems 22, no. 2 (March 2000): 224–64. http://dx.doi.org/10.1145/349214.349219.

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13

Park, Woo-Jun, Myung-Joon Lee, and Kwang-Moo Choe. "On the reduction of LR(k) parsers." Information Processing Letters 47, no. 5 (October 1993): 245–51. http://dx.doi.org/10.1016/0020-0190(93)90134-u.

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14

Kanakaraddi, Suvarna G., and Suvarna S. Nandyal. "Bottom up Fuzzy Parsers: Fuzzy Simple LR, Fuzzy Canonical LR and Fuzzy LALR Parsers for Parsing Natural language." International Journal of Engineering and Technology 9, no. 3S (July 17, 2017): 417–21. http://dx.doi.org/10.21817/ijet/2017/v9i3/170903s064.

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15

Degano, Pierpaolo, and Corrado Priami. "Comparison of syntactic error handling in LR parsers." Software: Practice and Experience 25, no. 6 (June 1995): 657–79. http://dx.doi.org/10.1002/spe.4380250606.

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16

Leung, Hing, and Detlef Wotschke. "On the size of parsers and LR(k)-grammars." Theoretical Computer Science 242, no. 1-2 (July 2000): 59–69. http://dx.doi.org/10.1016/s0304-3975(98)00199-6.

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17

Fuketa, M. "Efficient controlling of parsing-stack operation for LR parsers." Information Sciences 118, no. 1-4 (September 1999): 145–57. http://dx.doi.org/10.1016/s0020-0255(99)00040-7.

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18

Bermudez, Manuel E., and Karl M. Schimpf. "A general model for fixed look-ahead lr parsers." International Journal of Computer Mathematics 24, no. 3-4 (January 1988): 237–71. http://dx.doi.org/10.1080/00207168808803647.

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19

Snelting, Gregor. "How to build LR parsers which accept incomplete input." ACM SIGPLAN Notices 25, no. 4 (April 1990): 51–58. http://dx.doi.org/10.1145/987481.987485.

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20

Ukkonen, Esko. "Upper bounds on the size of LR(k) parsers." Information Processing Letters 20, no. 2 (February 1985): 99–103. http://dx.doi.org/10.1016/0020-0190(85)90072-9.

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21

Slivnik, Boštjan. "On different LL and LR parsers used in LLLR parsing." Computer Languages, Systems & Structures 50 (December 2017): 108–26. http://dx.doi.org/10.1016/j.cl.2017.06.002.

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22

Sassa, Masataka, and Ikuo Nakata. "A simple realization of LR-parsers for regular right part grammars." Information Processing Letters 24, no. 2 (January 1987): 113–20. http://dx.doi.org/10.1016/0020-0190(87)90104-9.

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23

Witaszek, Jacek. "A practical method for finding the optimum postponement transformation for LR(k) parsers." Information Processing Letters 27, no. 2 (February 1988): 63–67. http://dx.doi.org/10.1016/0020-0190(88)90093-2.

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24

Jabri, Riad. "A generic parser for strings and trees." Computer Science and Information Systems 9, no. 1 (2012): 381–410. http://dx.doi.org/10.2298/csis101109004j.

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In this paper, we propose a two fold generic parser. First, it simulates the behavior of multiple parsing automata. Second, it parses strings drawn from either a context free grammar, a regular tree grammar, or from both. The proposed parser is based on an approach that defines an extended version of an automaton, called positionparsing automaton (PPA) using concepts from LR and regular tree automata, combined with a newly introduced concept, called state instantiation and transition cloning. It is constructed as a direct mapping from a grammar, represented in an expanded list format. However, PPA is a non-deterministic automaton with a generic bottom-up parsing behavior. Hence, it is efficiently transformed into a reduced one (RBA). The proposed parser is then constructed to simulate the run of the RBA automaton on input strings derived from a respective grammar. Without loss of generality, the proposed parser is used within the framework of pattern matching and code generation. Comparisons with similar and well-known approaches, such as LR and RI, have shown that our parsing algorithm is conceptually simpler and requires less space and states.

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25

Leermakers, René, Lex Augusteijn, and Frans E. J. Kruseman Aretz. "A functional LR parser." Theoretical Computer Science 104, no. 2 (October 1992): 313–23. http://dx.doi.org/10.1016/0304-3975(92)90128-3.

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26

Lenka, Dillip Kumar, and Pawan Kumar. "States merging in LR parser." ACM SIGPLAN Notices 41, no. 4 (April 2006): 24–29. http://dx.doi.org/10.1145/1147214.1147219.

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27

Sorkin, Arthur, and Peter Donovan. "LR(1) parser generation system." ACM SIGSOFT Software Engineering Notes 36, no. 2 (March 14, 2011): 1–5. http://dx.doi.org/10.1145/1943371.1943391.

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28

Barnard, David T., and James R. Cordy. "SL parses the LR languages." Computer Languages 13, no. 2 (January 1988): 65–74. http://dx.doi.org/10.1016/0096-0551(88)90010-0.

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29

Tang, Hong Jun. "An LR Parser with Less States." Applied Mechanics and Materials 310 (February 2013): 684–87. http://dx.doi.org/10.4028/www.scientific.net/amm.310.684.

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This paper presents a new construction method of LR parser which is based on the theory of deterministic finite automata. The deterministic infinite automata are simplified for obtaining the LR parsing table with fewer states by merging the equivalent states. The new construction method has the same reorganization power as LALR parser but avoids the “reduce/reduce” conflict in LALR method. The experiment results show that the number of states in parsing table can be reduced greatly if the proposed method is used.

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30

Spector, D. "Efficient full LR(I) parser generation." ACM SIGPLAN Notices 23, no. 12 (December 1988): 143–50. http://dx.doi.org/10.1145/57669.57684.

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31

Lee, Gyung-Ok, and Kwang-Moo Choe. "An LR parser with pre-determined reduction goals." Information Processing Letters 72, no. 5-6 (December 1999): 189–96. http://dx.doi.org/10.1016/s0020-0190(99)00146-5.

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32

Jourdan, Jacques-Henri, and François Pottier. "A Simple, Possibly Correct LR Parser for C11." ACM Transactions on Programming Languages and Systems 39, no. 4 (September 18, 2017): 1–36. http://dx.doi.org/10.1145/3064848.

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33

Clarke, Gwen, and David T. Barnard. "Error handling in a parallel LR substring parser." Computer Languages 19, no. 4 (October 1993): 247–59. http://dx.doi.org/10.1016/0096-0551(93)90010-x.

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34

D.SolomonRaju, R., and Pawan Kumar. "State Merging in LR Parser under Count based Reduction." International Journal of Computer Applications 100, no. 17 (August 20, 2014): 19–31. http://dx.doi.org/10.5120/17616-8235.

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35

Cormack, G. V. "An LR substring parser for noncorrecting syntax error recovery." ACM SIGPLAN Notices 24, no. 7 (July 1989): 161–69. http://dx.doi.org/10.1145/74818.74832.

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36

Zafar, Nazir Ahmad. "LR(K) Parser Construction Using Bottom-up Formal Analysis." Journal of Software Engineering and Applications 05, no. 01 (2012): 21–28. http://dx.doi.org/10.4236/jsea.2012.51004.

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37

Clarke, Gwen, and David T. Barnard. "An LR Substring Parser Applied in a Parallel Environment." Journal of Parallel and Distributed Computing 35, no. 1 (May 1996): 2–17. http://dx.doi.org/10.1006/jpdc.1996.0063.

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38

Lim, Jintaeck, Gayoung Kim, Seunghyun Shin, Kwanghoon Choi, and Iksoon Kim. "Parser Generators Sharing LR Automaton Generators and Accepting General Purpose Programming Language-based Specifications." Journal of KIISE 47, no. 1 (January 31, 2020): 52–60. http://dx.doi.org/10.5626/jok.2020.47.1.52.

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39

Finn, Gerard D. "Extended use of null productions in LR(1) parser applications." Communications of the ACM 28, no. 9 (September 1985): 961–72. http://dx.doi.org/10.1145/4284.4289.

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40

Ho, Edward Kei Shiu, and Lai Wan Chan. "Extracting error productions from a neural network-based LR parser." Neurocomputing 47, no. 1-4 (August 2002): 189–206. http://dx.doi.org/10.1016/s0925-2312(01)00588-4.

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41

STONE, ROGER G., and GADA F. KADODA. "Token-by-token Syntax-directed Editing (Using an LR Parser)." Software: Practice and Experience 26, no. 11 (November 1996): 1247–60. http://dx.doi.org/10.1002/(sici)1097-024x(199611)26:11<1247::aid-spe59>3.0.co;2-n.

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42

Pratama, Mudafiq Riyan, Sri Kusumadewi, and Taufiq Hidayat. "PENERAPAN ALGORITMA LALR PARSER DAN CONTEXT-FREE GRAMMAR UNTUK STRUKTUR KALIMAT BAHASA INDONESIA." Jurnal Teknologi Elektro 8, no. 1 (April 21, 2017): 1. http://dx.doi.org/10.22441/jte.v8i1.1364.

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Penyajian bahasa dalam bentuk tulisan, dapat menyimpan pengetahuan dari generasi ke generasi berikutnya. Setiap penulisan karya tulis seperti buku, hendaknya ditulis dengan tata bahasa yang benar sesuai kaidah-kaidah bahasa Indonesia, karena akan berpengaruh pada kesempurnaan proses penyampaian ide atau pesan. Parsing adalah proses untuk memeriksa kebenaran struktur kalimat berdasarkan suatu grammar (tata bahasa). Salah satu algoritma untuk parsing kata dalam Context-Free Grammar (CFG) adalah LALR Parser. LALR Parser merupakan salah satu varian dari LR Parser yang mampu menangani grammar (Gupta, 2013). Uji coba dilakukan pada tiga jenis kalimat yaitu kalimat tunggal, kalimat majemuk setara, dan kalimat majemuk bertingkat. LALR Parser efektif dalam melakukan parsing terhadap CFG bahasa Indonesia pada kalimat tunggal (nilai akurasi 90.30%), kalimat majemuk setara (nilai akurasi 76.66%), dan kalimat majemuk bertingkat (nilai akurasi 78.57%). Kegagalan deteksi dipengaruhi oleh 3 hal yaitu (1) struktur kalimat tidak sesuai dengan kaidah bahasa Indonesia, (2) unsur pembentuk kalimat tidak tersedia dalam CFG, dan (3) kata yang terdapat dalam kalimat tidak tersedia dalam lexicon.

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43

Rodriguez-Leon, C., and L. Garcia-Forte. "Solving difficult LR parsing conflicts by postponing them." Computer Science and Information Systems 8, no. 2 (2011): 517–31. http://dx.doi.org/10.2298/csis101116008r.

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Though yacc-like LR parser generators provide ways to solve shift-reduce conflicts using token precedences, no mechanisms are provided for the resolution of difficult shift-reduce or reduce-reduce conflicts. To solve this kind of conflicts the language designer has to modify the grammar. All the solutions for dealing with these difficult conflicts branch at each alternative, leading to the exploration of the whole search tree. These strategies differ in the way the tree is explored: GLR, Backtracking LR, Backtracking LR with priorities, etc. This paper explores an entirely different path: to extend the yacc conflict resolution sublanguage with new constructs allowing the programmers to explicit the way the conflict must be solved. These extensions supply ways to resolve any kind of conflicts, including those that can not be solved using static precedences. The method makes also feasible the parsing of grammars whose ambiguity must be solved in terms of the semantic context. Besides, it brings to LR-parsing a common LL-parsing feature: the advantage of providing full control over the specific trees the user wants to build.

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44

Denny, Joel E., and Brian A. Malloy. "The IELR(1) algorithm for generating minimal LR(1) parser tables for non-LR(1) grammars with conflict resolution." Science of Computer Programming 75, no. 11 (November 2010): 943–79. http://dx.doi.org/10.1016/j.scico.2009.08.001.

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45

Zipunov, A. V., and S. V. Valganov. "RHYTHMIC SEMANTIC STRUCTURES “PARTICULARS AND UNIVERSALS” IN THE LYRICS OF ART SONGS AND ALGORYTHMS OF THEIR DETECTION." Bulletin of Udmurt University. Series History and Philology 31, no. 2 (May 11, 2021): 359–64. http://dx.doi.org/10.35634/2412-9534-2021-31-2-359-364.

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In order to study holistic cultural phenomena, including art songs, a tool reminiscent of LR(k)-parser of context-free grammars has been formalized. With the help of this algorithm a two-pass analysis of two works by different authors, united by the common theme of overcoming, was carried out. Two common structures were revealed in the texts: the semantic alternation of the "particulars and universals" oppositions (PU-rhythm) and the arrhythmic motif of overcoming (O-structure).

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46

Landa, Rebecca J., Rachel Reetzke, Madiha Tahseen, and Christine Reiner Hess. "Early behavioral profiles elucidating vulnerability and resiliency to later ASD outcomes." Development and Psychopathology 32, no. 4 (September 15, 2020): 1217–29. http://dx.doi.org/10.1017/s0954579420000814.

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AbstractInfant siblings of children with autism spectrum disorder (ASD) exhibit greater heterogeneity in behavioral presentation and outcomes relative to infants at low familial risk (LR), yet there is limited understanding of the diverse developmental profiles that characterize these infants. We applied a hierarchical agglomerative cluster analysis approach to parse developmental heterogeneity in 420 toddlers with heightened (HR) and low (LR) familial risk for ASD using measures of four dimensions of development: language, social, play, and restricted and repetitive behaviors (RRB). Results revealed a two-cluster solution. Comparisons of clusters revealed significantly lower language, social, and play performance, and higher levels of restricted and repetitive behaviors in Cluster 1 relative to Cluster 2. In Cluster 1, 25% of children were later diagnosed with ASD compared to 8% in Cluster 2. Comparisons within Cluster 1 between subgroups of toddlers having ASD+ versus ASD− 36-month outcomes revealed significantly lower functioning in the ASD+ subgroup across cognitive, motor, social, language, symbolic, and speech dimensions. Findings suggest profiles of early development associated with resiliency and vulnerability to later ASD diagnosis, with multidimensional developmental lags signaling vulnerability to ASD diagnosis.

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47

Nasser, Ahmed, and Hayri Sever. "A Concept-based Sentiment Analysis Approach for Arabic." International Arab Journal of Information Technology 17, no. 5 (September 1, 2020): 778–88. http://dx.doi.org/10.34028/iajit/17/5/11.

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Concept-Based Sentiment Analysis (CBSA) methods are considered to be more advanced and more accurate when it compared to ordinary Sentiment Analysis methods, because it has the ability of detecting the emotions that conveyed by multi-word expressions concepts in language. This paper presented a CBSA system for Arabic language which utilizes both of machine learning approaches and concept-based sentiment lexicon. For extracting concepts from Arabic, a rule-based concept extraction algorithm called semantic parser is proposed. Different types of feature extraction and representation techniques are experimented among the building prosses of the sentiment analysis model for the presented Arabic CBSA system. A comprehensive and comparative experiments using different types of classification methods and classifier fusion models, together with different combinations of our proposed feature sets, are used to evaluate and test the presented CBSA system. The experiment results showed that the best performance for the sentiment analysis model is achieved by combined Support Vector Machine-Logistic Regression (SVM-LR) model where it obtained a F-score value of 93.23% using the Concept-Based-Features+Lexicon-Based-Features+Word2vec-Features (CBF+LEX+W2V) features combinations

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48

Saikia, Payaswini, Elmar Körding, Deanne L. Coppejans, Heino Falcke, David Williams, Ranieri D. Baldi, Ian Mchardy, and Rob Beswick. "15-GHz radio emission from nearby low-luminosity active galactic nuclei." Astronomy & Astrophysics 616 (August 2018): A152. http://dx.doi.org/10.1051/0004-6361/201833233.

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We present a sub-arcsec resolution radio imaging survey of a sample of 76 low-luminosity active galactic nuclei (LLAGN) that were previously not detected with the Very Large Array at 15 GHz. Compact, parsec-scale radio emission has been detected above a flux density of 40 μ Jy in 60% (45 of 76) of the LLAGN sample. We detect 20 out of 31 (64%) low-ionization nuclear emission-line region (LINER) nuclei, ten out of 14 (71%) low-luminosity Seyfert galaxies, and 15 out of 31 (48%) transition objects. We use this sample to explore correlations between different emission lines and the radio luminosity. We also populate the X-ray and the optical fundamental plane of black hole activity and further refine its parameters. We obtain a fundamental plane relation of log LR = 0.48 (±0.04) log LX + 0.79 (±0.03) log M and an optical fundamental plane relation of log LR = 0.63 (±0.05) log L[O III] + 0.67 (±0.03) log M after including all the LLAGN detected at high resolution at 15 GHz, and the best-studied hard-state X-ray binaries (luminosities are given in erg s−1 while the masses are in units of solar mass). Finally, we find conclusive evidence that the nuclear 15 GHz radio luminosity function (RLF) of all the detected Palomar Sample LLAGN has a turnover at the low-luminosity end, and is best-fitted with a broken power law. The break in the power law occurs at a critical mass accretion rate of 1.2 × 10−3 M⊙ yr−1, which translates to an Eddington ratio of ṁEdd ~ 5.1 × 10−5, assuming a black hole mass of 109 M⊙. The local group stands closer to the extrapolation of the higher-luminosity sources, and the classical Seyferts agree with the nuclear RLF of the LLAGN in the local universe.

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49

Liao, Mai, Minfeng Gu, Minhua Zhou, and Liang Chen. "The X-ray emission in young radio active galactic nuclei." Monthly Notices of the Royal Astronomical Society 497, no. 1 (June 4, 2020): 482–97. http://dx.doi.org/10.1093/mnras/staa1559.

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ABSTRACT In this work, we investigated the X-ray emission for a sample of young radio active galactic nuclei (AGNs) by combining data from Chandra/XMM–Newton with data for other wavebands. We find strong correlations between the X-ray luminosity LX at 2–10 keV and the radio luminosities LR at 5 GHz for the VLBI radio-core, VLA radio-core and Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) component, indicating that both parsec- and kiloparsec-scale radio emissions are strongly correlated with X-ray emission in these sources. We find an approximately linear dependence of the radio on the X-ray luminosity in the sources with radiatively efficient accretion flows (i.e. the Eddington ratio Redd ≳ 10−3), with b ∼ 1 ($L_{\rm R}\, \propto \, L_{\rm X} ^{b}$) and $\xi _{\rm RX}\, \sim$ 1 in the fundamental plane using the VLBI data. The dependence is consistent with the re-analysed results of a previous study of Fan and Bai at Redd ≳ 10−3, but is significantly different from the theoretical prediction of accretion flow as the origin of X-ray emission. In contrast to the case for radio-quiet quasars, there is no significant correlation between Γ and the Eddington ratio. Our results seem to indicate that the X-ray emission of high-accretion young radio AGNs may be from the jet. We constructed the spectral energy distributions (SEDs) for 18 sources (most of which are in radiatively efficient accretion), namely nine galaxies and nine quasars with high-quality X-ray data, and find that the X-ray emission of most quasars is more luminous than that of normal radio-quiet quasars. This is clearly seen from the quasar composite SED, in which the X-ray emission is apparently higher than that of radio-quiet quasars, probably supporting jet-related X-ray emission in young radio AGNs. The possibility that the X-ray emission is from self-synchrotron Compton is discussed.

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50

Hernandez, Josefino G. "Nasal Saline Irrigation for Sinonasal Disorders." Philippine Journal of Otolaryngology-Head and Neck Surgery 22, no. 1-2 (November 28, 2007): 37–39. http://dx.doi.org/10.32412/pjohns.v22i1-2.807.

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Abstract:

Nasal saline irrigation is a simple easy-to-do procedure that has been used to treat sinus and nasal conditions for many years. Wingrave in his 1902 paper “The Nature of Discharges & Douches” discussed cleansing of the nasal passages as an important method of treating different nasal illnesses in the last part of the 19th century.1 Nasal saline irrigation has been used for such sinonasal conditions as atrophic rhinitis, rhinosinusitis and allergic rhinitis, among infants with nasal problems and patients who have undergone endoscopic sinus surgery. Past recommendations for use were based on anecdotal evidence such as reports of patients living near the sea, whose symptoms improved with natural seawater irrigation while swimming. The past two decades saw studies undertaken to support what has been in practice for many years. Taccariello studied 40 patients suffering from chronic sinusitis with 19 patients receiving traditional alkaline nasal douche and 21 patients receiving sterile sea water spray. Results showed that compared to the control group who received no treatment, douching per se improved endoscopic appearance and quality of life scores.2 Georgitis compared the use of nasal hyperthermia versus saline irrigation in patients with allergic rhinitis. Histamine levels fell with both forms of treatment with greatest declines seen with irrigation. Leukotriene C4 levels were significantly reduced by irrigation.3 Pediatricians have refrained from using oral and topical decongestants among infants. Excessive use of oral decongestants can result in cardiovascular side effects, while excessive use and sufficient absorption of topical decongestants can result in possible complications of CNS depression leading to coma and marked reduction in body temperature, especially in infants in whom these drugs should not be used.4 Nasal saline irrigation has become a good alternative. Another common use follows endoscopic sinus surgery, when the nasal cavity quickly becomes encrusted, and frequent cleaning and saline irrigation are needed for 4-8 weeks until the lining of the nose and sinuses has regenerated.5 Nasal saline irrigation moisturizes the nasal cavity and reduces dryness of the nasal mucosa. It has become important in clearing nasal crusts and thick mucous in patients with rhinosinusitis and has been known for its beneficial effect among patients with sinonasal problems. Saline solutions can be classified into isotonic or hypertonic, buffered or non-buffered. Preparations include powder, spray or mist forms; with and without preservative; and with and without dispenser. The number of available products in the market can make it difficult for the doctor to decide on what product to recommend for his suffering patient, ranging from inexpensive home-made preparations to very expensive imported solutions. Different studies will be presented which may help in this choice. Isotonic or hypertonic solution The main issue at hand is whether to use an isotonic or hypertonic solution. Traissac from the University ENT Hospital – Bordeaux, in a study of 410 patients using isotonic solution, showed the beneficial action on the nasal sinus mucosa in medical disease and after sugery.6 Tomooka (University of California, 2000) in a study of 211 patients using hypertonic saline solution, showed improvement in 23 of the 30 symptoms queried.7 Talbot, in 1997, demonstrated among 21 volunteers that 3% hypertonic saline solution decreased mucociliary saccharine transit times more than 0.9% normal saline, 3.1 minutes compared to 0.14 minutes less than baseline.8 This study was corroborated by Keojampa in 2004, demonstrating that buffered hypertonic saline improved saccharine clearance time more than buffered normal saline.9 Hypertonic saline solution decreases the viscosity of mucus which could have improved saccharine clearance time. However, it has been suggested that the saccharin dissolution method provides a less accurate assessment of mucociliary clearance against tagged insoluble particles, as the saccharin mixes between sol and gel layers of the mucociliary blanket and is not carried solely in the superficial gel layer.8 Boek from the University Hospital Utrecht studied the effect of different saline solutions on the ciliary beat frequency (CBF) of cryopreserved mucosa of the sphenoidal sinus measured by a photoelectric method. Results revealed that Locke-Ringer’s solution (LR) had no effect on the CBF, NaCI 0.9% had a moderately negative effect, NaCI 7% solution led to complete ciliostasis within 5 minutes (reversible after rinsing with LR), and 14.4% hypertonic solution had an irreversible ciliostatic effect. He concluded that LR is an isotonic solution with no effect on ciliary beat frequency.10 Therefore, it is probable that this solution is more appropriate than saline for nasal irrigation or antral lavage. This was further supported by the study of Min YG published in 2001, wherein isotonic and hypotonic solutions did not decrease ciliary beat frequency, but where ciliostasis was observed within a few minutes in the 3.0% and 7.0% solutions.11 Histologic changes showed disruption of nasal epithelial cells in vitro which could have resulted in decrease ciliary beat frequency in hypertonic solutions. Buffered or non-buffered solution The effect of pH on the rate of mucociliary clearance of the douching solution was also studied. One group was given hypertonic solution buffered to pH 8 and another group given non-buffered hypertonic solution.12 Results showed no difference in mucociliary clearance between solutions buffered to pH 8 and that which is non-buffered.12 In his paper, Taccariello noted that alkaline nasal douche improved endoscopic appearance but not the quality of life score, while sea water spray showed improved quality of life but not endoscopic appearance.2 Preparations Preparations for nasal saline irrigation in the market include powder which can be freshly prepared for use or ready-to-use spray or mist solutions which need preservatives to extend shelf life. Common preservatives are benzalkonium chloride, polyethylene glycol and propylene glycol. Bezalkonium chloride is an antibacterial preservative which may be potentially toxic to the mucosa. Krayenbuhl and Seppey (1995) compared application of a saline stream versus drops (passive saline instillation) among 104 patients who underwent intranasal surgeries. Stream patients required significantly fewer post-operative recovery days and visits to physicians. The recovery period with saline stream was 18.9 days versus 36.7 days using saline drops.5 Nasal saline preparations available in the local market include isotonic drops, isotonic and hypertonic sprays, and isotonic seawater sprays. Parsons in 1996 presented a recipe for patients to prepare their own nasal saline solution:8 Carefully clean and rinse a 1-quart glass jar. Fill the jar with tap water. Add 2 to 3 heaping teaspoons of “pickling/canning” salt. Add 1 rounded teaspoon of baking soda (pure bicarbonate). Stir and shake well before use. Store at room temperature. This will result in a 3% saline solution buffered to pH 7.6. If the mixture is too strong and results in a stinging effect in the nose, less salt (1 ½ tsp of salt) can be used. For children, it is best to start with a weaker salt water mixture which can be gradually increased in tonicity. Ordinary rock salt is used since iodine in iodized salt can be toxic to the nasal mucosa. A soft plastic catsup container can be used as a dispenser. The nose can be liberally irrigated 2-3 times per day. Nasal saline irrigation has been safely used by both children and adults with no documented serious side effects. Different studies have shown that both isotonic and hypertonic nasal saline irrigations have beneficial effects in many sinonasal conditions. The exact mechanism by which improvement is effected is unclear.7 Hypotheses for why nasal saline irrigation promotes improvement of nasal symptoms include the following: improving mucociliary clearance decreasing mucosal edema decreasing inflammatory mediators mechanically clearing nasal crusts and thick mucous The choice of which nasal saline solution to use depends on the physician and is mainly based on which studies he or she will believe in. Whether to recommend a saline solution prepared by the patient at home or saline solutions that are commercially available is really up to the doctor. Commercial solutions have the advantage of being sterile. Saline prepared at home is cheaper, but sterility may not be guaranteed and the percentage of tonicity may be variable. Although several studies have shown that hypertonic saline solutions improve saccharine transit time, other studies have likewise shown that hypertonic saline solutions affect ciliary beat frequency negatively. For this reason, isotonic saline solutions which do not affect ciliary beat frequency may be more appropriate than hypertonic saline solution for nasal irrigation. However, we cannot discount the mucolytic effect induced by the hyperosmolarity of hypertonic solutions which could have improved saccharine transit time. Further studies can be undertaken to finally determine which solution, isotonic or hypertonic, would be better to use as nasal saline irrigation for the different sinonasal disorders.

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