Intra-operative gas exchange and post-operative hypoxaemia.

The relation between intra-operative gas exchange and post-operative oxygen saturation was examined using pulse oximetry (SpO2) 30 h after anaesthesia for upper abdominal surgery. The inspired oxygen partial pressure (PIO2) was varied during anaesthesia to produce a plot of PIO2 vs. SpO2. Gas exchange during anaesthesia was inferred from the relation between PIO2 and SpO2 which was described by its lateral and vertical displacement away from the position of a standard oxygen dissociation curve. With patients breathing air, the SpO2 was measured over a 10-min period at 30 h after surgery. The correlation coefficient of the lateral displacement with post-operative SpO2 was 0.7, and that of the vertical displacement with post-operative SpO2 was 0.66. The correlation coefficient of intra-operative SpO2 at PIO2 = 21 kPa with post-operative SpO2 was 0.69. It can be concluded that gas exchange abnormalities during anaesthesia deduced from the displacement of the PIO2 vs. SpO2 curve correlate with SpO2 30 h post-operatively and may help to identify patients at risk of post-operative hypoxaemia.

Complications following general anaesthesia for cataract surgery: a comparison of the laryngeal mask airway with tracheal intubation.

The incidence of airway complications following general anaesthesia using either a tracheal tube or a laryngeal mask airway was compared in a prospective, randomized study of 79 patients undergoing elective cataract surgery using a standard anaesthetic technique. Assessment was made both at extubation (which was taken to include removal of the laryngeal mask airway) and for 25 min afterwards. There was a significantly greater incidence of coughing prior to extubation (P < 0.001), at extubation (P < 0.001) and after extubation (P < 0.001) in the tracheal group than in the laryngeal mask airway group. No other airway complications were seen in either group.