THORACIC EPIDURAL ANALGESIA STARTED AFTER CARDIOPULMONARY BYPASS - ADRENERGIC, CARDIOVASCULAR AND RESPIRATORY SEQUELAE

The effects of thoracic epidural analgesia started after cardiopulmona ry bypass were studied on the subsequent adrenergic, cardiovascular an d respiratory responses. Sixteen cardiac surgical patients received ei ther a standardised general anaesthetic (control group) or a standardi sed general anaesthetic and thoracic epidural analgesia (epidural grou p). The epidural catheter was sited before surgery and heparinisation. Following discontinuation of cardiopulmonary bypass, patients in the epidural group were given 15 ml bupivacaine 0.5% down the catheter fol lowed by an infusion of bupivacaine 0.375% at 5-8 ml.h(-1) after surge ry. The control group received an intravenous morphine infusion on com pletion of surgery. The adrenergic response was assessed by measuring arterial catecholamine concentrations. Respiratory function was determ ined by spirometry, peak expiratory flow and arterial partial pressure of oxygen while breathing air. Pain scores were also obtained. After cardiopulmonary bypass the increases in catecholamine concentrations w ere effectively inhibited in the epidural group for the remainder of t he study (p < 0.05). Postoperative respiratory function was less impai red in the epidural group, with higher forced expiratory volume in 1 s , forced vital capacity and peak expiratory flow (p < 0.05). Pain scor es were also significantly lower in the epidural group (p < 0.05). The re were no significant differences in cardiovascular parameters.