The use of single dose of sodium citraie as a prophylaxis against acid aspiration syndrome in obstetric patients undergoing caesarian section

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1 Med. J. Malaysia Vl. 46 N. 4 December 1991 The use f single dse f sdium ciraie as a prphylaxis agains acid aspirain syndrme in bseric paiens underging caesarian secin S. K. Lim, MBBS, M. MED. Lecurer E. O. Elegbe, MBBS, D. A., FFARCSI Prfessr Deparmen f Anaeshesilgy, Faculy f Medicine, Universii Kebangsaan Malaysia, lalan Raja Muda, Kuala Lumpur Summary The effeciveness f sdium ciarae as a prphylaxis agains acid aspirain syndrme was sudied in 3 grups f bseric paiens. Grup I was he cnrl grup which cnsised f 20 paiens in esablished labur wh were n likely require caesarian secin. N anacid had been given hese paiens. Grup II cnsised f 20 paiens wh underwen elecive caesarian secin, while Grup HI cnsised f anher 20 paiens wh underwen emergency caesarian secin. Grup II and In were given 30mi fo.3m sdium cirae as sn as hey arrived in he perain heare. The gasric cnen was aspiraed afer he inducin f anaeshesia and a he end f surgery jus befre exubain. The vlume was measured and a sample sen fr ph analysis. Sdium cirae was fund increase he gasric ph significanly in bh Grup II and HI paiens when cmpared wih Grup I paiens wh underwen emergency caesarian secin. We cnclude ha 30ml f 0.3M sdium cirae is effecive in increasing gasric ph hugh i ends be assciaed wih an increase in gasric vlume. Key wrds: Obseric anaeshesia, caesarian secin, sdium cirae as prphylaxis agains acid aspirain. Inrducin Pulmnary aspirain f ( isric cnen (Mendelsn syndrme) in bscric paiens cninues be ne f he cmmnes causes f maernal mrbidiy and mraliyl. The severiy and he exen f pulmnary damage is relaed he ph2 and he vlume3 f maerial aspiraed. I is generally agrecd ha a ph flcss han 2.5 is a criical level fr prducing severe pulmnary damage. I is als suggesed by Rbers and ShirJey3 ha a gasric cnen f mre han 25ml. is a hrea pregnan paiens shuld aspirain ccur. Many prevenive mcasures have been advcaed aler he gasric ph and vlumc a safe level. These include empying he smach mechanically and pharmaclgically(meclrprmide); neuralisain f gasric cnens by anacids r H2 rccepr anagniss. In he Maerniy Hspial Kuala Lumpur, a single dse f mis. magncsium risilicae (MMT) was used neuralise he gasric cnen fr paiens ging fr Caesarian Secin (LSCS) unil 1984 when i was replaced by O.3M sdium cirae. A sudy by Tan 4 in his hspial in 1984 shwed ha a single dse f mis. magnesium risilicae(15 ml) given befre general anaeshesia fr LSCS dccreased he number f paiens a risk (ph less han 2.5) frm 53% (wihu MMT) 20% (wih MMT). Hwever in view f he reprs 349

2 ha aspirain fmmt neuralized gasric cnen culd sill give rise chemical pneumniis 5 6 he auhr prpsed he use f sdium cirae as a safer alernaive since his has been shwn cause much less pulmnary damage when aspiraed? Wih he availabiliy f 0.3M sdium cirae in his hspial in 1985, i has been given all paiens cming fr LSCS jus prir inducin f anaeshesia. Since n sudy has been repred in his hspial n he effeciveness f sdium cirae in neuralizing he gasric cnen, we have underaken his sudy evaluae is effeciveness in neuralizing he gasric cnen f paiens scheduled fr elecive and emergency LSCS. Maerials and mehds 3 grups, each made up f 20 bseric paiens were sudied afer apprval was bained frm he Ehical Research Cmmiee. Grup I This was he Cnrl Grup cnsising f paiens f ASA 1 r 2 wh were in esablished labur. N anacid had been given. A Ryle's ube was insered afer paiens' cnsen had been bained and a sample f he gasric juice was aspiraed and sen fr ph analysis. Grup n This cnsised f paiens scheduled fr elecive LSCS under general anaeshesia. Grup III This cnsised f paiens wh required emergency LSCS under general anaeshesia. Fr grups II and Ill, n premedicain was given. As sn as he paien arrived in he perain heare, 30 m!. f 0.3 M sdium cirae was given rally. All paiens had a rapid sequence inducin wih pre-xygenain, hipenne, cricid pressur, suxamehnium, and inubain. Anaeshesia was mainained wih 50% nirus xide in xygen, 0.5% halhane, and a nn-deplarising muscle relaxan. Afer delivery f he baby, inravenus pehidine lmg!kg was given and anaeshesia mainained wih 67% nirus xide in xygen. ' Fllwing inubain, a Ryle's ube was passed in he smach and gasric cnen aspiraed. Aemps were made empy he smach as much as pssible by repeaed aspirain while adjusing he psiin f he R yle' s ube. Vlume f he aspirae was measured and a sample sen fr ph analysis. Afer cmplein f he surgery, jus befre exubain, he gasric cnen was again aspiraed, he vlume measured and a sample sen fr ph analysis. The ph f he gasric cnen was measured by Cming ph meer. Resuls were analysed using Suden's Hes and Chi-square es. A p value f < 0.05 was cnsidered as sigl)ifican. Resuls The paiens' characerisics are summarised in Table 1. There was n significan difference beween he 3 grups wih regards heir age and weigh. There was als n significan difference beween he elecive and emergency grup wih regards he fasing inerval and medicain - aspirain inerval as shwn in Table 2. The mean ph f gasric aspirae f he paiens in Grup II and Grup III cmpared wih ha f Grup [ a inducin and jus befre exubain are as shwn in Table 3. Sdium cirae significanly raised 350

3 Table I Paiens' characerisics. Values expressed in mean (S.D.) Grup I Grup 11 Grup III (Cnrl) (Elecive) Emergency) Number (n) Age (years) 28.8 (5.6) 27.6 ( 5.5) 28.3 (4.4) Weigh (Kg) 60.4 (8.3) 62.9 (11.1) 62.0 (11.2) Table 11 Fasing inerval & medicain-gasric aspirain inerval in elecive and emergency LSCS paiens Values expressed in mean (S.D.) Fasing inerval (hurs) Medicain -aspirae inerval (minues) 1 s aspirae 2nd aspirae Elecive (Grup 11) 10.2 ( 2.6) 19.8 (10.5) 56.7 (14.1) Emergency (Grup Ill) 8.7 ( 4.6) 15.4 ( 5.9) 49.7 (12.4) he ph f gasric aspirae f paiens in Grup II and Grup Ill. In Grup I, 75% f he paiens had a gasric ph fless han 2.5 while in Grup 11, all paiens had gasric ph mre han 2.5 a bh inducin and jus befre exubain, and in he Grup III nly ne paien had ph less han 2.5 jus befre exubain (Table 4). Figures 1 and 2 shw he disribuin f he gasric ph f Grup 11 and Grup III paiens a inducin when cmpared wih Grup I paiens. The vlume f ga<;ric aspirae a inducin and jus befre exubain fr Grup II and Grup III paiens wh underwen LSCS are shwn in Table 5. The vlume f gasric aspirae end be larger in paiens underging emergency LSCS (Grup Ill) han in he elecive grup (Grup II), hugh he difference was n saisically significan. Grup III paiens had a wider range f vlume f gasric aspirae han Grup 11 paiens (Table 5). Six paiens (30%) in Grup 11 and nine paiens (45%) in Grup III had a vlume f gasric aspirae f greaer han 25ml. a inducin. Jus befre exubain here were six paiens in Grup III and nne in Grup 11 wih a vlume f gasric aspirae f greaer han 25ml (Table 4). 351

4 Table m: Gasric ph f LSCS paiens a inducin and exubain crn pared wih cnrl grup. Values expressed in mean (range) Grup I (cnrl) Grup n (Elecive) Grup HI (Emergency) ( ) Inducin Exubain ( ) ( ) #5.36 ( ) #5.22 ( ) + significan beween Grup 11 and Grup I a p < 0.05 # significan beween Grup If I and Grup I a p < 0.05 Table IV N f LSCS paiens a "risk" (ph < 2.5, Vlume> 25ml.) Inducin ph < 2.5 Vl> 25ml. Exubain ph< 2.5 VI > 25ml. Grup n (elecive) 6 (30%) Grup III (emegency) 9 (45%) 6 (30%) N f p a i e n s ~ Gasric ph _ Grup S ~Gmupll Fig. 1 : Gasric ph f elecive LSCS paiens (Grup II) a inducin cmpared wih cnrl grup (Grup J) 352

5 N f p Cl i e n s '& Gasric ph.. Grup I Fig. 2 : Gasric ph f emergency LSCS paiens (Grup UI) a inducin cmpared wih cnrl grup (Grup I) Table V Vlume f gasric aspirae in LSCS paiens. Values expressed in mean m!. (range) Inducin Exubain Tal Grup n (Elecive) 21.3 (1-65) 10.3 (3-21) 31.6 (5-71) Grup HI (Emergency) 26.8 (2-126) 17.4 (2-90) 44.2 ( ) Discussin Obseric paiens underging LSCS are ms suscepible hazards f aspirain during inducin f anaeshesia jus befre inubain and during emergence frm anaeshesia jus afer exubain. I is generally acceped haa ph fless han 2.5 and a gasric vlume f mre ha 25 ml. expse he paiens he risk f severe pulmnary damage shuld aspirain ccur 9. This presen sudy shwed ha 30 m!. f O.3M sdium cirae given jus befre he inducin f anaeshesia fr elecive and emergency LSCS was effecive in raising he gasric ph abve he criical level f 2.5 in alms all paiens and mainained a his level hrughu he durain f he surgery. This is in agreemen wih he sudies dne by Gibbs e alio, Abbud e api, and Dewan e al 12. In he sudy by Tan4, where I5ml fmmt was given bseric paiens jus prir he inducin f anaeshesia fr emergency LSCS, 20% f 353

6 he paiens had a gas:ril; ph f less han 2.5. The range f ph in his paiens was while in he presen sudy he range f ph in paiens wh were given sdium cirae was much narrwer. This seems sugges he pssjbiliy f inadequae mixing fmmt wih he gasric juice in Tan's paiens, giving rise pckes f unneuralized gasric cnen. Sdium cirae was mre cnsisen in raising he gasric ph in bh he elecive and emergency siuains. We als ned ha here was n significan variain in he gasric ph beween he 2 samples clleced frm each paien. This seems suppr he fac ha sdium cirae, being a clear anacid, mixes mre evenly wih he gasric juice han MMT, as n aemps were made mix he anacid wih he gasric cnen by rain r side mvemen f ur paiens as described by Hldswrh and c-wrkers (1980p. The larges vlume f gasric aspirae recrded in his sudy was 126 m!. which was bained frm a paien a inducin wh underwen emergency LSCS, while in he elecive grup he larges vlume was 65 ml. The larger vlume f gasric aspirae in he emergency grup is ms likely due he delayed gasric empying which ccurs during labur and which may be increased by any narcic analgesic which had been given. Even jus befre exubain 30% f his grup f paiens sill had a gasric aspirae f mre han 25 m!. Our mehd f aspirain f he gasric cnen hwever, des n ensure he cmplee rerieval f all he gasric cnen, i is likely ha larger vlumes were presen. This indicaes ha here is sill a risk f pulmnary aspirain, and all bseric paiens requiring LCSC shuld sill be regarded as having a "full smach". In cnclusin, a single dse f 30m!. f O.3M sdium cirae given jus befre he inducin f anaeshesia is effecive in neuralizing he acidic gasric cnen f paiens underging elecive and emergency LSCS. Hwever because i ends increase he gasric vlume especially in paiens underging emergency LSCS, aspirain f he gasric cnen can sill ccur. Therefre he usual prphylacic maneuvers e.g. rapid sequence inducin, cricid pressure and endrachael inubain mus be emplyed and vigilance n he par f he anaesheis cann be subsiued. The use f ~ recepr anagniss may be f use in such siuains as hey have been shwn increase gasric ph and reduce gasric vlume 14 Acknwledgemen We wish hank all he anaesheic medical fficers wh have helped in he cllecin f he gasric aspiraes, he Head f he Dep. f Obseric and Gynaeclgy, UKM, he Siser and Nurses f he Maerniy Operain Theare, fr heir c-perain. We als wish hank Encik Alias Lajis fr his assisance in he ph analysis. References I Mrgan M. Anaesheic cnribuin maemal mraliy. Br. J. AJUll!sh., 1987; 59: Teabeau JR. Aspirain f gasric cnens - experimenal sudy. Am.J. Pahl., 1952; 28: Rbers RB., Shirley MA. Reducing he risk f acid aspi rain during Caesarian Secin. Anesh. Analg., 1974; 53: Tan KH. Single dse anacid herapy befre Caesarian Secin. Med. J. Malaysia., 1984; 39: Gibbs CP., Schwarz DJ., Wynne JW., Hd Cl, Kuck El. Anacid pulmnary aspirain in he dg. Aneshesilgy., 1979; 51: Taylr G. Acid pulmnary aspirain syn drme afer anacids. A case repr. Br. J. Anaesh., 1975; 47: Eyler SW., Cullen BF., Welch WD., Murphy M. Anacid aspirain in rabbis. Anesh. Analg., 1982; 61: Vanfam LD. Aspirain f gasric cnens in he peraive perid. N. Engl. I_ Med., 1965; 273:

7 Exarhs ND., Lgan WD JR., AbbL OA. The imprance f ph and vlume in rachebrchial aspirain. Dis. Ches., 1965; 47: Gibbs CP., Sphr L., Schmid D. The effeciveness f sdium cirae as an anacid. Aneshsilgy., 1982; 57:44-6. Abbud TK., Curis J., Earl S., e al. Efficacy f clear anacid prphylaxis in bseric. Aca. Aneshesil. scand., 1984; 28: Dewan DM., Flyd HM., Thislewd JM., Bgard TD., spielman FJ. Sdium cirae prereamen in elecive Caesarian Secin paiens. Anesh. Analg., 1985; 64: Hldswrh JD., Jhnsn KR., Mascall G., Gwynne Rulsn R., Tmlinsn PA. Mixing f anacids wih smach cnens: anher apprach he prevenin f he acid aspirain (Mendelsn' s) syndrme. Anaesh., 1980; 35; 641. FrankM., Evans M., Flynn P., Aun C. Cmparisn f he prphylacic use f Magnesium risilicae mixure B.P.C., Sdium cirae mixure r cimeidine in bserics. Br. J. Anaesh., 1984; 56: