Supplementary Oxygen and the Laryngeal Mask Airway—Evaluation of a Heat-and-Moisture Exchanger

Abstract

Heat-and-moisture exchangers (HMEs) are routinely used in anaesthesia for the humidification and warming of inspired gases. The use of the Laryngeal Mask Airway (LMA) is widespread, and many anaesthetists choose to leave it in situ until the patient regains consciousness. In this study, we have investigated the effectiveness of an HME as a means of administering supplemental oxygen via LMA in the immediate postoperative period. Oxygen was administered at varying flow rates via the gas sampling port of the HME and the oxygen delivery recorded, using end-tidal oxygraphy as a measure of alveolar Po₂. At an oxygen flow rate of 4 l.min⁻¹, the HME provided a mean end-tidal oxygen concentration of 36.2% (±6.2), which compares favourably to other previously described devices. The HME thus represents a convenient, effective and economical means of oxygen supplementation via the LMA.

Keywords

laryngeal mask airway;oxygen supplementation

References

Newton

N.I.

Supplementary oxygen—potential for disaster. Anaesthesia 1991; 46: 905–906.

Brimacombe

, Berry

Barotrauma and the LMA. Anaesthesia 1994; 49: 1009.

Goodwin

A.P.L.

Postoperative oxygen via the laryngeal mask airway. Anaesthesia 1991; 46: 700.

Broadway

P.J.

, Royle

Supplementary oxygen and the laryngeal mask airway. Anaesthesia 1990; 45: 792–793.

Kennedy

, Meyer

, Joyce

Supplemental oxygen using an LMA. Anaesth Intensive Care 1992; 20: 118.

Lewis

R.P.

, Porter

Supplementary oxygen and the laryngeal mask airway. Anaesthesia 1991; 46: 70.

Kumar

C.M.

Supplementary oxygen and the laryngeal mask airway: use of a paediatric breathing circuit. Today's Anaesthetist 1995; 10: 68.

Martin

, Brimacombe

J.R.

Oxygen enrichment during emergence with the laryngeal mask airway—the “T-bag” versus the T-piece. Anaesthesia 1997; 52: 1195–1198.

Dashfield

A.K.

, Langton

J.A.

, Johnston

C.G.

, Eickmann

Two oxygen delivery devices compared in a modified laryngeal mask airway. Can J Anaesth 1997; 44: 572–573.

10.

Berry

C.B.

, Myles

P.S.

Preoxygenation in healthy volunteers: a graph of oxygen “washin” using end-tidal oxygraphy. Br J Anaesth 1994; 72: 116–118.

11.

Myles

P.S.

, Heap

, Langley

Agreement between end-tidal oxygen concentration and the alveolar gas equation: pre- and post cardiopulmonary bypass. Anaesth Intensive Care 1993; 21: 240.