Domiciliary oxygen concentrators in anaesthesia: preoxygenation techniques and inspired oxygen concentrations

A conventional preoxygenation technique was compared in two volunteers with two techniques based on a drawover breathing system supplied with oxygen enriched air from a Devilbiss Mini VO2 domiciliary oxygen concentrator. Breathing from a 20-litre bag, filled previously at 2 litre min-1 from the concentrator was as effective as the conventional technique (PaO2 73.2 kPa). Supplying 4 litre min-1 to a drawover system was less effective (PaO2 35.5 kPa). We present a simple method for determining the inspired oxygen concentration obtained under conditions of drawover anaesthesia using an oxygen concentrator.