1046

portal hypertensive rates,"21 it was logical to see

whether beta-adrenergic antagonists were effective insevere gastric mucosal haemorrhage. Two small openstudies have shown that propranolol stops such

bleeding in almost all cases,23.24; in a randomisedcontrolled trial in a larger number of patients thefrequency of rebleeding was significantly reduced. 1The mechanism of the beneficial effect of propranololis uncertain. There is no evidence yet that the

long-term outcome of cirrhotic patients with severeportal hypertensive gastropathy, or those with

bleeding varices, is improved by either surgery orbeta-adrenergic blockade.

1. Perez-Ayuso RM, Piqué JM, Bosch J, et al. Propanolol in prevention ofrecurrent bleeding from severe portal hypertensive gastropathy incirrhosis. Lancet 1991; 337: 1431-34.

2. McCormack TT, Sims J, Eyre-Brook I, et al. Gastric lesions in portalhypertension: inflammatory gastritis or congestive gastropathy? Gut1985; 26: 1226-32.

3. Quintero E, Piqué JM, Bombi JA, et al. Upper gastrointestinal bleedingcaused by gastroduodenal vascular malformations: incidence,diagnosis, and treatment. Dig Dis Sci 1986; 31: 897-905.

4. Dagradi AE, Mehler R, Tan DT, Stempien SJ. Sources of uppergastrointestinal bleeding in patients with liver cirrhosis and largeesophagogastric varices. Am J Gastroenterol 1970; 54: 458-63.

5. Khodadoost J, Glass GBJ. Erosive gastritis and acute gastroduodenalulcerations as source of upper gastrointestinal bleeding in livercirrhosis. Digestion 1972; 7: 129-38.

6. Walram S, Davis M, Nunnerley H, et al. Emergency endoscopy aftergastrointestinal haemorrhage in 50 patients with portal hypertension.Br Med J 1974; 4: 94-96.

7. Terés J, Bordas JM, Bru C, Diaz F, Bruguera M, Rodes J. Uppergastrointestinal bleeding in cirrhosis: clinical and endoscopiccorrelation. Gut 1976; 17: 37-40.

8. Thomas E, Rosenthal WS, Rymer W, Katz D. Upper gastrointestinalhemorrhage in patients with alcoholic liver disease and esophagealvarices. Am J Gastroenterol 1979; 72: 623-29.

9. Rector WG, Reynolds TB. Risk factors for haemorrhage from

oesophageal varices and acute gastric erosions. Clin Gastroenterol 1985;14: 139-53.

10. Perez-Ayuso RM, Piqué JM, Saperas E, at al. Gastric vascular ectasias incirrhosis: association with hypoacidity not related to gastric atrophy.Scand J Gastroenterol 1989; 24: 1073-78.

11. Tarnawski AS, Sarfeh IJ, Stachura J, et al. Microvascular abnormalitiesof the portal hypertensive gastric mucosa. Hepatology 1988; 8: 1488-94.

12. Papazian A, Braillon A, Dupas JL, Sevenet F, Capron JP. Portal

hypertensive gastric mucosa: an endoscopic study. Gut 1986; 27:1199-203.

13. Quintero E, Piqué JM, Bombi JA, et al. Gastric mucosal vascular ectasiascausing bleeding in cirrhosis. Gastroenterology 1987; 93: 1054-61.

14. Foster PN, Wyatt JI, Bullimore DW, Losowsky MS. Gastric mucosa inpatients with portal hypertension: prevalence of capillary dilatation andCampylobacter pylori. J Clin Pathol 1989; 42: 919-21.

15. Hashizume M, Tanaka K, Mokuchi K. Morphology of gastricmicrocirculation in cirrhosis. Hepatology 1983; 6: 1008-12.

16. Benoit JN, Granger DN. Splanchnic haemodynamics in chronic portalhypertension. Sem Liv Dis 1986; 6: 287-98.

17. Kitano S, Koyanasi K, Sugimachi M, Kobayashi M, Inokuchi K.Mucosal blood flow and modified vascular responses to norepinephrinein the stomach of rats with liver cirrhosis. Surg Res 1982; 14: 221-30.

18. Piqué JM, Leung FW, Kitahora T, Sarfeh IJ, Tarnawski A, Guth PH.Gastric mucosal blood flow and acid secretion in portal hypertensiverats. Gastroenterology 1988; 95: 727-33.

19. Piqué JM, Pizcueta P, Perez-Ayuso RM, Bosch J. Effects of propanololon gastric microcirculation and acid secretion in portal hypertensiverats. Hepatology 1990; 12: 476-80.

20. Benoit JN, Womack WA, Korthuis RJ, Wilborn WH, Granger DN.Chronic portal hypertension: effects on gastrointestinal flowdistribution. Am J Physiol 1986; 250: G535-39.

21. Sarfeh IJ, Juler GL, Stemmer EA, et al. Results of surgical managementof hemorrhagic gastritis in patients with gastro-esophageal varices.Surg Gynecol Obstet 1982; 155: 167-70.

22. Kroeger RJ, Groszmann RJ. Effect of selective blockade of B2-adrenergicreceptors on portal systemic hemodynamics in a portal hypertensive ratmodel. Gastroenterology 1985; 88: 896-900.

23. Quintero E, Piqué JM, Bombi JA, et al. Antral mucosal hyperaemia:

characterization of a portal hypertension-related syndrome causinggastric bleeding in patients with cirrhosis. J Hepatol 1985; 1 (suppl):S315.

24. Hosking SW, Kennedy HJ, Seddon I, Triger DR. The role of

propranolol in congestive gastropathy of portal hypertension.Hepatology 1987; 7: 437-41.

Laryngeal mask airwayThe laryngeal mask has been described as the

missing link between the facemask and theendotracheal tube. It consists of a tubular

oropharyngeal airway, to the distal end of which isattached a sealed, forward-pointing mask with aninflatable peripheral cuff. This apparatus is designedto produce an airtight seal around the laryngeal inletand so provide a secure airway suitable for

spontaneous or controlled ventilation.In most cases the laryngeal mask can be inserted

easily without laryngoscopy; a muscle relaxant isseldom required. Once in place the device gives betterand more secure airway control than the facemask;and there is no need to support the patient’s chin.lConsequently, the anaesthetist’s hands are freed, andremote observation of the patient may be possiblewhen tracheal intubation would otherwise beessential. Scavenging of waste anaesthetic gases is aseffective from laryngeal masks as from tracheal tubes3and the device is also well tolerated during recoveryfrom anaesthesia.4 Fibreoptic bronchoscopes passeddown laryngeal masks have been used to observe thefunctioning of the vocal cords, an examination notpossible during endotracheal anaesthesia.5,6Thus it is not surprising that the laryngeal mask has

quickly been adopted into anaesthetic practice andmany applications have been reported. What is theproper place of this device in airway management?The endotracheal tube is the gold standard by whichall other methods of airway control are judged. Oncein position it provides a secure airway that facilitateseasy ventilation and prevents aspiration of

regurgitated gastric contents.The laryngeal mask is easy to position and use

whereas tracheal intubation is a skilled procedure.Moreover, anatomical or pathological anomalies maketracheal intubation impossible in certain patients,even for experienced personnel. The laryngeal maskhas been used successfully in patients of all ages inwhom tracheal intubation had proved impossible.7-9The mask can itself be used as an aid to difficultintubation- a small cuffed endotracheal tube10 or a

gum-elastic bougiell (used to railroad an endotrachealtube into the position after removal of the laryngealmask) can be passed into the trachea through correctlyplaced size 3 and 4 laryngeal masks. The use of thedevice in obstetric patients who have provedimpossible to intubate is controversial. When learningto do obstetric anaesthesia, all anaesthetists are taughta failed intubation drill-maintenance of cricoid

pressure (to prevent aspiration) and, if necessary,turning the patient onto her side head down andventilating her with 100% oxygen until she awakes. In

1047

exceptional circumstances of extreme fetal distress,mask anaesthesia with an inhalation agent when the

patient is on her side, head down, may be entertainedto continue the operation but normal teaching wouldbe to wake the patient. The priority is to keep themother alive by making sure oxygen gets to her lungs,but sometimes the airway becomes completelyobstructed and will remain so until the short-actingmuscle relaxant, given to facilitate intubation, wearsoff. In these circumstances a laryngeal mask may allowan airway to be maintained and thus prevent hypoxia.Sometimes laryngeal masks have saved lives, so it hasbeen suggested that the mask is an essential itemwherever obstetric anaesthesia is practised.12 Patientswith laryngeal spasm13 and inadequate reversal ofneuromuscular blockade14 have likewise been

successfully treated.The laryngeal mask may itself cause airway

obstruction. Total obstruction occurs after insertionin 1 % and partial obstruction is seen in about 10% ofadultsis and 19% of children.16 Displacement of theepiglottis or aryepiglottic folds by the mask seems tobe the main cause; occasionally the epiglottis maybecome trapped between the pliable grates on theanterior surface of the device.17 Overall, the maskprovides a satisfactory airway in 96-98% ofpatients16and airway patency does not deteriorate during thecourse of anaesthesia.111 Nevertheless, when surgicalprocedures or patient position make airway securityparamount, a tracheal tube should be used. Leakage ofgas at the seal between the mask and the larynx whenventilator pressures exceed 1-7-2-0 kPa18 limits theusefulness of the device for controlled ventilation in

patients with high inflation pressures.Unlike the tracheal tube the laryngeal mask does

not prevent aspiration of gastric contents silentaspiration19 and aspiration pneumonia have beenreported. 20 In a fibreoptic study, the oesophagus couldbe seen via the laryngeal mask in 3 of 50 patientsexamined. 15 Regurgitation of dye followingpreoperative ingestion of methylene blue capsules wascompared in patients breathing spontaneously via afacemask and Guedel airway (a curved airway thatreaches as far as the back of the tongue) or via alaryngeal mask. There was no regurgitation in patientsbreathing via the facemask whereas one-third of thoseusing the laryngeal mask showed evidence ofcontamination.21 A possible explanation is that thepharyngeal response to insertion of the laryngeal maskresembles that to a bolus of food; part of this responseis to allow relaxation of the lower oesophaeal sphincterand consequent regurgitation. The laryngeal maskairway may also trap gastric contents below it, makingcontamination of the airways more likely.19

Cardiovascular stress responses to insertion oflaryngeal masks are similar but less pronounced thanthose seen during endotracheal intubation.22 Traumato the uvula23 and pharyngeal tonsilsz4 has beenreported, although such risks are slight with goodinsertion technique. 26 7% of patients complain

of postoperative sore throat vs 50% after trachealintubation.26The laryngeal mask can be inserted and used by

unskilled personnel. Davies et a127 showed that RoyalNavy medical trainees could successfully place anduse the mask in 94% of cases vs 51% with trachealtubes. Similar results were found when the laryngealmask was used in a military field hospital,28 Evenamong ambulancemen who have received extended

training, only 61 % can achieve an 80% success ratewith tracheal intubation.29 Nevertheless, use of thelamygeal masks in emergencies is likely to be limitedby their failure to prevent gastric aspiration.

1. Sarma VJ. The use of a laryngeal mask airway in spontaneously breathingpatients. Acta Anaesthesiol Scand 1990; 34: 669-72.

2. Taylor DH, Child CS. The laryngeal mask for radiotherapy in children.Anaesthesia 1990; 45: 690.

3. Sarma VJ, Leman J. Laryngeal mask and anaesthetic waste gasconcentrations. Anaesthesia 1990; 45: 791-92.

4. Maltby JR, Loken RG, Watson NC. Clinical appraisal of the laryngealmask airway. Can J Anaesth 1990; 37: S108.

5. Akhtar TM. Laryngeal mask airway and visualisation of vocal cordsduring thyroid surgery. Can J Anaesth 1991; 38: 140.

6. McNamee CJ, Meyns B, Pagliero KM. Flexible bronchoscopy via thelaryngeal mask. Thorax 1991; 46: 141-42.

7. Denny NM, Desilva KD, Webber PA. Laryngeal mask airway foremergency tracheostomy in a neonate. Anaesthesia 1990; 45: 895.

8. Allen JG, Flower EA. The brain laryngeal mask. An alternative todifficult intubation. Br Dental J 1990; 168: 202-04.

9. McClune S, Regan M, Moore J. Laryngeal mask airway for caesareansection. Anaesthesia 1990; 45: 227-28.

10. Brain AJ. Further developments of the laryngeal mask. Anaesthesia 1990;44: 530.

11. Allison A, McCrory J. Tracheal placement of a gum elastic bougie usingthe laryngeal mask airways. Anaesthesia 1990; 45: 419-20.

12. De Mello WF, Kocan M, McClune S, Moore JA. The laryngeal mask infailed intubation. Anaesthesia 1990; 45: 689-90.

13. Michel MZ, Stubbing JF. Laryngeal mask airway and laryngeal spasm.Anaesthesia 1991; 46: 71.

14. Kumar CM. Laryngeal mask airway for inadequate reversal. Anaesthesia1990; 45: 792.

15. Payne J. The use of the fibreoptic laryngoscope to confirm the position ofthe laryngeal mask. Anaesthesia 1989; 44: 865.

16. Rowbottom SJ, Simpson DL, Grubb D. The laryngeal mask airway inchildren, a fibreoptic assessment of positioning. Anaesthesia 1991; 46:489-91.

17. Miller AC, Bickler P. The laryngeal mask airway, an unusual

complication. Anaesthesia 1991; 46: 659-60.18. Brodrick PM, Webster NR, Nunn JF. The laryngeal mask airway. A

study of 100 patients during spontaneous breathing. Anaesthesia 1989;44: 238-41.

19. Cyna AM, MacLeod DM, Campbell JR, Criswell J, John R. Thelaryngeal mask: cautionary tales. Anaesthesia 1990; 45: 167-68.

20. Griffin RM, Hatcher IS. Aspiration pneumonia and the laryngeal maskairway. Anaesthesia 1990; 45: 1039-40.

21. Barker P, Murphy P, Langton JA, Rowbottam DJ. Regurgitation ofgastric contents during general anaesthesia using the laryngeal maskairway. Anaesthetic Research Society meeting, Manchester, 1991.

22. Braude N, Clements EA, Hodges UM, Andrews BP. The pressorresponse and laryngeal mask insertion: a comparison with trachealintubation. Anaesthesia 1989; 44: 551-54.

23. Lee JJ. Laryngeal mask and trauma to uvula. Anaesthesia 1989; 44:1014-15.

24. Van Heerden PV, Kirrage D. Large tonsils and the laryngeal mask airway.Anaesthesia 1989; 44: 703.

25. Brain A. Proper technique for the insertion of the laryngeal mask.Anaesthesiology 1990; 73: 1053-54.

26. Alexander CA, Leach AB. Incidence of sore throats with the laryngealmask. Anaesthesia 1989; 44: 791.

27. Davies PR, Tighe SQ, Greenslade GL, Evans GH. Laryngeal maskairway and tracheal tube insertion by unskilled personnel. Lancet 1990;336: 977-79.

28. De Mello WF, Ward P. The use of the laryngeal mask airway in primaryanaesthesia. Anaesthesia 1990; 45: 792-93.

29. Wilson ME. Assessing intravenous cannulation and tracheal intubationtraining. Anaesthesia 1991; 46: 578-79.