the in spontaneously breathing anaesthetised adult

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1 Anaesth ntensive Care 21; 3g: l1g_122 Randomised comparison of LMA Supreme,' with -Gel'* in spontaneously breathing anaestised adult patients E. E E CHEW*, N. H. M.ASHMt, C. Y. WANG+ Department of Anaessia, Facuto) of Medicine, [Jniversity Malaya, Lembah pantai, Kuala Lumpur, Malaysia SUMMARY we compared pe(oftnance of LMA supreme'* (slma) spontaneously breathing with adult -Gel,, patients' during Ninety anaessia patients in with or )merican were studied society of in Anessiotogists a prospective physical raniomised status controlled oropharyngeal study. leak pressure' our primary we itso ourcome compared measure overall of ventilation qnd insenion'success incidence,ot", of complicatrinl. oy inseftion, The adequacy mean (sd) oropharyngear reak pressure "iri 25.6 (5.1) cmh,o, which wai for slma sreair thatn yo, tn" wqs overall ).1'fi.il-iyjzg insertion lcri g=o.ooot1. success rates were The similar bitween first attempt and h.ro P='132)' The slma noui, rity4 2Va *a oi.an,, rated',orr", rcrt 93.3 io inrert and.vo, than (P='433),i, llca-e=.r), similqr The.incidence out tlte ii*" rotrn of complications for inseftion better t";;, with both gro_ups. -Get than The grade LLMA (i=o.ool). ot' fibreoptic view we conclude wqs easier to iili insert * and provides adults with nimnl a higher airways, o)opharyngeal slma leak pressure. is but fibreoptic views orc i,ruu with i_gel. Key words: laryngear mask airway, LMA Supreme, insertion, fibreoptic, oropharyngear leak pressure Since introduction of LMA Classic"" laryngeal mask ulryuy (ntravent Orthofix, Maidenhead, UK) i it has gained widespread oopulariry,. The LMA SupremJ." (SLMA) and -Gel" are two newly developed Oisposable supraglottic airway devices- The craimed potential advantages of both devices include easier insertion, more effective ventilation, better airway protection, compression and stability' fbllowing T:llTll1isue lnsertlon,.. The SLMA is a single_use LMA with a built_in gastric drain tube, elliptical airway tube for easy plu":t"lr and prevention of kinking, an integral bite-bl ock, a rar ge pre -curved cuff for eifective airway seal, moulded fins in cuff to protect airway from epiglottic folding and a reinforced tip and moulded distal cuff to prevent folding at tip. The -Gel is also a single_use sufraglottic device with built-in gastric drain tube. ti cjnsists ot an anatomical firm tube section and an anatomical. M.B.,8.S., Medical Officer. t M.8., B.S.; M.Anaes., Lecturer. f M.8., Ch.B., ER.C.A., professor. correspondence: professor ^Add13ss.fm C. y. Wang, Deparrment of or l.l::^rih.::]i.facurry Medicine. Universiry rra.rrvr. l",it# - '-- Kuata dantai,563 ' Lumpur. Malaysia. uangcyto rm.eoulmy Accepted for publication on June 24,27. non-inflatable cuff section. Along tubing is an integral bite_block, an elliptiil buccal civity stabiliser that eliminates rotation and provides vertical strength to aid insertion, and a V_shaned connector to cuff to prevent kinking. t has an anatomical non_inflatable silicon cuff that seals laryngeal inlet and prevents neurovascular compression at larynx. An epiglottic rest at cuff prevents downfolding of in"e epigtottis and laryngeal inlet obstruction. We were interested in se two devices due to ir claimed advantages, and rise in routine use of disposable supraglottic airway adjuncts for maintenance of anaessia in ou, institution. Therefore we designed a study to compare performance of SLMA and _Gei during anaessia in spontaneously breathing adult Our ourcome tll"litl.ollnluv. oropharyngeal leak.pressure (OLp). Secondary outcomes included number of insertion attempts, ease of insertion, passage of a gastric tube, manipulations required, ventilation quality and fibreoptically determined laryngeal view grade. METHODS ^ With approval from University Malaya Medical Centre Ethical Committee and informed written consent, we studied 9 patients (American Society of Anaessiq and ntensive Care, Vol. 3g, No. 6, November 2.t t t

2 LMA SUPREME'" WTH THE -GEL"" N ADULT PATENTS 119 in US WAS 'acy qnd )7o, tton 4is gis wity 'ides rped san ;eals :ular : and ie to ;tine ; for Ltion. uring adult ngeal uded rtion, rired, nined :dical ritten ety of rcr 21 Anessiologists physical status or ), aged 16 to 55 years, undergoing elective surgery not requiring tracheal intubation. Exclusion criteria included patients who were at risk of regurgitation of gastric contents or if y had pathology of neck, upper respiratory or upper alimentary tracts, previous or anticipated airway problems or body mass index >35 kg.m'. All patients were fasted overnight. ntravenous access obtained and all patients received standard monitoring before induction of anaessia. Patients' heads were supported on a firm silicone headrest and were kept in a neutral position. After preoxygenation for three minutes, anaessia induced with fentanyl2. pg.kg' and propofol 2 mg.kg'. nduction of anaessia confirmed by loss of verbal contact with patient, loss of eyelash reflex and relaxation of jaw. f coughing, gagging or body movement occurred during insertion, a furr dose of propofol.5 mg.kg' given to achieve an adequate depth of anaessia. Anaessia maintained with sevoflurane 2 to 3% in oxygen. ntermittent fentanyl boluses were given for additional analgesia. After induction, patients were randomly allocated to one of two groups using sequentially allocated numbered, sealed opaque envelopes containing name of one of two devices. A single anaestist (with experience in using LMA Classic" on more than 5 patients), who had used SLMA and -Gel devices 2 times, inserted devices. Both devices were inserted according to manufacturer's instructions including weight-based recommendations for size (SLMA: size 3 for patients"3 to 5 kg, size 4 for patients 5 to 7 kg, size 5 >7 kg; -Gel: size 3 for patients 3 to 6 kg, size 4 for patients 5 to 9 kg, size 5 for patients >9 kg). The standard pre-use tests were performed. Both devices were lubricated using a water-based lubricant on tip and posterior surface as recommended by manufacturers, and SLMA fully deflated prior to insertion. After insertion, SLMA device n inflated to a pressure of 6 cmhro using a handheld pressure gauge device (VBM, Medizintechnik, Sulz, Germany). After insertion of airway. breathing system connected to device. An initial assessment of airway patency and ability to ventilate lungs made by gently squeezing reservoir bag, while observing presence of end-tidal carbon dioxide waveforms and chest movement. f it not possible to ventilate lungs, following airway manoeuvres were allowed: chin-lift, jawthrust, head extension or flexion on neck. After Anaessia and ntensive Care, VoL 38, No. 6, November 21 any manoeuvre, adequacy of ventilation reassessed. f it not possible to insert device or ventilate through it, one more attempt at insertion allowed. A failed attempt defined as removal of device from mouth. f placement failed after two attempts, patient withdrawn from study and insertion recorded as a failure. The time to insertion, defined as time from picking up device to obtaining first end-tidal carbon dioxide trace, measured by an independent observer. The ease of insertion graded as L:easy, 2=moderate, 3=difficult or 4:impossible. The number of insertion attempts recorded. Once ventilation successful, as confirmed by CO, waveform and chest movement, OLP of each device measured, i.e. minimum airway pressure at which gas audibly leaks around airway using a fresh gas flow of 3 l.minute'1 with adjustable pressure-limiting valve completely closed. The peak airway pressure is not allowed to exceed 4 cmhro. Following this, device's anatomic positioning evaluated by fibreoptic endoscopy using following scoring system6: 1=vocal cords entirely visible;2:vocal cords or arytenoids cartilages partially visible; 3=epiglottis only visible; 4:no laryngeal structures visible. During maintenance of anaessia, if re airway obstruction, adjusting position of device or patient's head and neck or removal and reinsertion of device were allowed. The number of manipulations of each device during insertion and maintenance of anessia were recorded. At end of operation device removed after patient regained consciousness and opened his or her mouth to command. The presence or absence ofblood on device, injury to teeth or lips and incidence of perioperative complications (i.e. coughing, gagging, hiccup, vomiting, regurgitation, aspiration, laryngospasm and bronchospasm, hypoxia [peripheral oxygen saturation, oxygen saturation measured by pulse oximetry <95%D were noted. Patients were asked one hour postoperatively by a blinded investigator wher y had a sore throat (yes or no). The sample size for OLP (primary outcome) based on a pilot study of 16 patients. The mean airway pressure at which gas leaked around -Gel 2 cmhro (SD 8 cmhro). Power analysis determined that a study of 31 patients in each group had 8% power to detect a difference in airway seal pressure of 5 cmhro. For secondary outcomes, we used reported incidence of overall attempt successful insertions of SLMA in non-paralysed

3 12 anaestised patients of 95 to 1Vo''" and a -ini-rr- clinically important difference of 2Vo UJ*""n -Gel and SLVte, based on using a nvo-tailed alpha value (.5) and a beta value ('2)' Under se conditions, a sample size of 45 patients per group estimated to be sufficient to detect a difference in success rate of 2Vo. We refore studied 9 patients. The data for OLP were normally distributed and Student's t-test used for analysis' nsertion times were not normally distributed and Mann- Whitney U-test used' The grade of fibreoptic view and number of manipulations were compared bt Mann-Whitney U-test' Complications and of ventilation between groups were "ifi"u"y by Fisher's exact test' Commercial SPSS ""-p"t"a 15.'softwaie for Windows (SPSS nc'' Chicago' -. USA) used for data processing' Data are presented as mean and standard deviations) range' interquartile range and percentage' P <'5 considered statistically significant' RESULTS Forty-five patients in each group were studied' Patienis'characteristics are presented in Thble 1' n one patient, SLMA inserted easily but ventilaiion unsuccessful and re no expiratory carbon dioxide waveform despite two uii"*ptt; an LMA Classic n inserted with "ury u"ntilution. During insertion, two patients in SLMA had complications related to laryngospasm despite easy insertion. These patients' data were exciuded from furr analysis during maintenance oi unu"*ttt"sia. Al a result, SLMA used for maintenance in 42 cases and -Gel for 45 cases' The first-time success rates ar achieving an effective airway were 44 of 45 (97'BVo) for SLMA and (93'3Vo) for -Gel' Tvo attempts were TABLE 1 E. F. F. CHEw, N' H. M' \;i;";;i_c,i,' ka,a, oy a",l;:";::1,"1;r"s are mean (sd) or Characteistics of patients (n=9) undergoing anaessia with Gender, M/F Age, y \ weight, kg Height, cm BM, kg.m' Mallampati scote, U2l3l 4 Size,3l415 SLMA (n=4s) 15/3 3s (1s) 61 (13) 161 (8) 23 (4) 36l8lUo 18t1819 -Gel (n=45) (116) 6 (1,2) 16 (8) 23 (s) 3s19lUo 23l22l SLMA=LMA Supreme'", M=male, F=female' BM=body mass index. HRSHtvt, C. Y. WaNc required in 2145 (4.4%) for -Gel' There on" fuilnr" to establish a patent airway with SLMA and none with -Gel' The ease of insertion rated easier in SLMA compared io f-c"f (P='11). However, time taken for insertion similar for two groups (P='433)' The OLP higher for SLMA than for 4el (P:.1). Once airway established' complications during anaessia were -infrequent for both devices. n one patient in SLMA group' airway became partially obstructed soon after itr".utg"ty started (one manipulation required to maintain a patent airway)' There were no ctmphcations requiring removal' patient in -One SLMA group developed mild laryngospasm and anor patient had hiccups soon after surgery started, which were self-limiting after administration of additional fentanyl' There were no arterial desaturations in eir group' Both devices were tolerated well during emergence from anaessia. The incidence of trauma' gastric iube passing at first attempt and perioperative compiications were similar between groups' Grade of dbreoptic view better for -Gel than SLMA (Table 2. P:'1)' TxstE 2 Comparison of SLMA and -Ge' Ease of insenion' measure' -irit, ona cimplications related to insertion of SLMA and f'c"t i" gg patieirc (for SLMA, n=42 for all number of -except itriprt ohd of insenion)' Values are (proportton)' "ot" "y!:i median (lqr[rangel) or mean (JDl' nsertion SLMA (n=45) -Gel (n=45) P value Attempts, U2lfailed r32 34lrlU 23t Ease of insertion, easy/moderate/ difficult/impossible nsertion time, s Manipulations LaryngosPasm Maintenance Oropharyngealeak pressure, cmhro Manipulations 2. (1s.-2s.2.(1s.-2s..433 [1s.-3.]) 2 (4.5Vo) [12.-3.]) (%).242 gl\,{tr (n=42) -Gel (n=45) 2s.6 (s.1) 2;1 (s.e) (2.4%) LaryngosPasm/hiccuPz (4.4%) Fibreoptic scoref, U2l3l4 Mucosal injury Sore throat 26t (7.rEo) 4 (e5%) (\Vo) 4U3llr 4 (8.e %) 2 (4.4%) P value f 1=vocal cords entirely visible,2=vocal.cords.or arytenolos ;;il;;";;idrv ]i';,,i;;';i.il"1 range. ui'iur", : = onlvisig[;o:l?]3119,1* sil'ra= lrita "piglottis Supreme'", QR = interquartile Anaessia antl ntensive Care, Vol 38, No' 6' November21

4 LMA SUPREME"" wth THE -GEL"" N ADULT PATENTS 121 r t, Lt,, )f,] u o n n ry E rh ce VE Ce a- ol ), ue. L 2 Llue 1 t3 l l1 23 :noids lngeai rartile r 21 DSCUSSON We found that SLMA OLP higher than -Gel and this both statistically significant and clinically relevant. As a result, SLMA may be more useful than -Gel for controlled ventilation. Our results differ from findings of Theiler et al who found that OLP similar between SLMA and -Gel'. The difference in our results might relate to different group of patients'q. We did not perform any power calculations for secondary outcome measures, so remainder of our findings must be considered exploratory. We found that SLMA slightly easier to insert compared to -Gel (P:.11) but clinical relevance of difference is not known. Moreover, time to achieve an effective airway similar between two devices. The first attempt and overall insertion success rates were similar between groups. This agrees with or studies that have shown a high success rate with both deviceslq'o. There one complete failure to establish a patent airway with SLMA despite easy insertion. No complete failure occurred in -Gel group. nsertion complications on or two patients with SLMAwere related to laryngospasm. During maintenance of anaessia airway clear throughout operation for most cases, except for one patient in SLMA group who needed one manipulation to maintain airway. There were two intraoperative complications in SLMA group and none in -Gel. One patient developed mild laryngospasm and or patient had hiccups. No conclusions can be drawn about incidence of se complications due to small numbers involved. There minimal blood-staining with both devices. This is similar to previous reportst'8'r. Postoperative sore throat also similar between devices. Fibreoptic view better with -Gel device. This suggests that device might be better suited to use as a conduit in difficult airway management and failed intubation, but larger studies would be required to confirm this finding. However, in this study we found no association between flbreoptic position and functioning of se devices. This is similar to or studies"'l2. Gastric tube insertion via drain tube successful at first attempt in all patients. This is also very similar to success rates reported in or studiest'''tu. Our study has a number of limitations. First, our study conducted in non-paralysed patients, hence our findings may be less applicable to paralysed patients. However, re is indirect Anaessia and ntensive Care, Vol. 38, No. 6, November 21 evidence from mucosal pressure studies that pharyngeal muscle tone is similar in paralysed and non-paralysed patients". Second, both devices were inserted by a single experienced user. Therefore, our results may not be applicable to inexperienced users. Furr studies are needed to assess ease of insertion and first time insertion success rate by novice users, as supraglottic airways are incorporated in difficult airway management protocol'z. Third, intraoperative data were collected by an unblinded observer, introducing a potential source of bias. We conclude that both devices are suitable for routine use during maintenance of anaessia in spontaneously breathing patients with normal airways, as both SLMA and -Gel appear to be effective in establishing a clinically patent airway and have high success rates of insertion and low morbidity. The SLMA provides a higher OLP. Our findings suggest also that SLMA might be slightly easier to insert than -Gel, and that fibreoptic views may be better with -Gel. ACKNOWLEDGEMENT The SLMAs used in this study were provided by Aerotrach Sdn Bhd, Malaysia and -Gels by Med Supplies (M) Sdn Bhd, Malaysia free of charge. REFERENCES 1. Brain AJ. The laryngeal mask: a new concept in airway management. Br J Anaesth 1983; 55: Americian Society of Anaessiologists Thsk Force on management of difficult airway. Practice guidelines for management of difficult airway: an updated report by American Society of Anaessiologists Task Force on Management of Difficult Airway. Anessiology 23; 98: Cook Gatward JJ, Handel J, Hardy R, Thompson C, Srivastava R et al. Evaluation of LMA Supreme'" in 1 non-paralysed patients. Alaessia 29; 64: Gatward JJ, Cook TM, Seller C, Handel J, Simpson Vanek V et al. Evaluation of size 4 i-gel'" airway in one hundred non-paralysed patients. Anaessia 28; 63:11, Timmermann A, Cremer S, Eich C, Kazmaier S, Briiuer A, Graf BM et al. Prospective clinical and fiberoptic evaluation of Supreme laryngeal mask airway. Anessiology 29; 11,: Verghese C, Berlet J, Kapila A, Pollard R. Clinical assessment of single use laryngeal mask airway - LMA-Unique. Br J Anaesth 1998; 8: Verghese C, Ramaswamy B. LMA-Supreme'" - a new singleuse LMA''" with gastric access: a report on its clinical efficacy. Br J Anaesth 28; 11: Theiler LG, Kleine-Brueggeney M, Kaiser D, Urwyler N, Luyet C, Vogt A et al. Crossover comparison of laryngeal mask supreme and i-gel in simulated difficult airway scenario in anestized patients. Anessiology 29; lll,'55-62.

5 HASHT,, C. Y. WaNc 9. Asai Muroa K, Yukawa H, Shingu K. Reevaluation of appropriate size of laryngeal mask airway. Br J Anaesth 1999; 83: Janakiraman C, Chethan DB, Wilkes AR, Stacey MR, Goodwin N. A randomised crossover trial comparing i-gel supraglottic airway and classic laryngeal mask airway. Anaessia 29; 64: Francksen H, Bein B, Cavus E, Renner J, Scholz J, Steinfath M et al. Comparison of LMA Unique, Ambu laryngeal mask and Soft Seal laryngeal mask during routine surgical procedures. Eur J Anaessiol 27; 24: Brimacombe J. Anatomy. n: Laryngeal mask anessia. Principles and practice, 2nd ed. London: WB Saunders Compnay 25. p. 73-L Keller C, Brimacombe J. nfluence of neuromuscular block, mode of ventilation and respiratory cycle on pharyngeal mucosal pressures with laryngeal mask airway. Br J Anaesth 1999;83: Anaessin and ntensive Care, Vol. 38, No. 6, November 21