Arterial desaturation during induction in healthy adults: should preoxygenation be a routine?

We studied the haemoglobin saturation of one hundred healthy patients equally divided into two groups. Group 1 patients received three minutes of preoxygenation prior to thiopentone induction followed by inhalational anaesthetics. Group 2 patients breathed room air prior to induction. None of the patients in Group 1 showed any arterial oxygen desaturation during the five minutes of the induction period, whereas 21 patients in Group 2 showed definite desaturation (P less than 0.005), of which fifteen patients had a saturation of 90% or less (P less than 0.005) and six had a saturation of 85% or less. Since those were healthy patients and the anaesthetics were given by experienced anaesthetists, we concluded that some form of preoxygenation should be used in all patients receiving general anaesthesia.