• S A Colbert, D M O'Hanlon, F Flanagan, R Page, and D C Moriarty.
• Department of Anaesthesia, Mater Misericordiae Hospital, Dublin, Ireland.
• Can J Anaesth. 1998 Jan 1; 45 (1): 23-7.

PurposeThe introduction of the laryngeal mask airway (LMA) has had a major impact on anaesthetic practice in the last ten years. Previous authors have demonstrated pressures equivalent to mean arterial blood pressure within the cuff of the LMA. This study examined the effects of cuff inflation on the cross sectional area, flow and velocity of blood flow at the level of the carotid sinus.MethodsSeventeen patients scheduled to have LMAs inserted as part of routine anaesthetic management were recruited into the study. Measurements of the common carotid artery bulb area, peak velocity and blood flow were performed upon LMA cuff inflation and deflation using a 5 MHz pulse wave Doppler probe.ResultsDeflation of the cuff resulted in an increase in the cross sectional area (from 0.58 +/- 0.05 to 0.64 +/- 0.04 cm2; P < 0.005), an increase in blood flow (from 65.6 +/- 5.6 to 73.9 +/- 5.6 cm3.sec-1; P < 0.05) and a slight but non significant increase in velocity of blood flow.ConclusionThis study demonstrates that inflation of the cuff on the LMA results in a decrease in carotid bulb cross sectional area which results in a decrease in blood flow.

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