PATTERNS OF OXYGENATION AFTER THORACOTOMY

We have studied patterns of oxygen saturation (Sp(O2)) before and after thoracotomy in 20 patients monitored nightly from the preoperative night to the fourth postoperative night. After operation, 10 patients received paravertebral bupivacaine (PVB) infusion and 10 received paravertebral saline (PVS) infusion. Papaveretum was given as required. Before operation the Sp(O2) profiles formed two groups: stable with Sp(O2) > 94% and stable with a median Sp(O2) less than 94% (hypoxaemia). During the first night after operation Sp(O2) profiles formed four groups: stable, not hypoxaemic (2/20); stable, hypoxaemic but improving (8/20); stable and constant hypoxaemia (5/20); unstable, hypoxaemic and deteriorating (5/20). Eleven patients remained hypoxaemic as late as the fourth night after operation. All patients who were hypoxaemic before operation were hypoxaemic after operation. Postoperative hypoxaemia was predicted in only 50% of cases. Papaveretum requirement was reduced in the PVB group, but regional analgesia did not affect the proportion of patients showing each Sp(O2) profile. Papaveretum caused a decrease in Sp(O2) in both analgesic groups.