PREOPERATIVE AND POSTOPERATIVE OXYGEN-SATURATION IN THE ELDERLY FOLLOWING SPINAL OR GENERAL-ANESTHESIA - AN AUDIT OF CURRENT PRACTICE

We have compared the incidence of preoperative and postoperative oxyge n desaturation in 20 elderly patients undergoing dynamic hip screw ins ertion for fractured neck of femur allocated randomly to two groups to receive subarachnoid anaesthesia (SA, n = 10) or a general anaestheti c (GA, n = 10). Oximetry data were recorded during the preoperative ni ght and the first 48 hours after surgery using Satmaster(TM) Data asso ciated with zero amplitude signal were automatically invalidated by th e software and decreases in SpO2 which were preceded by contemporaneou s changes in signal amplitude which conformed to a previously describe d template were assumed to be artefactual and were discarded from fina l data analysis. Data demonstrated a wide interpatient variability. Ho wever those patients who desaturated preoperatively continued to do so in the postoperative period. The differences between the preoperative and postoperative oximetry profiles were examined for each patient an d demonstrated a significantly longer time spent with SpO2 < 90% in th e GA group compared with the SA group, in all the recorded time period s, except on the day of surgery. The SA group showed an improvement in oxygen saturation postoperatively when compared to the preoperative n ight spending less time with an SpO2 < 85%. We conclude that the subar achnoid anaesthetic technique was associated with a lower incidence of postoperative oximetry desaturation when compared with general anaest hetic for these elderly patients undergoing repair of fractured neck o f femur.