Carotid artery surgery. Local versus general anaesthesia as related to sympathetic activity and cardiovascular effects

Arterial plasma catecholamines, blood pressure and heart rate were determined in 75 patients before, during and after carotid endarterectomy. Local anaesthesia given as a cervical block with skin infiltration containing 200 μg adrenaline was used in 28 patients (LA-group), general anaesthesia (nitrous oxide, fentanyl, isoflurane) with skin infiltration containing 200 μg adrenaline in 32 patients (GA s-group) and general anaesthesia without skin infiltration in 15 patients (GA o-group). In the LA-Group plasma noradrenaline (P-NA) levels were significantly higher during anaesthesia and surgery, with an increase from preanaesthesia levels ( P < 0.05). P-NA decreased from a preanaesthesia level in the GA o-group ( P < 0.01) but remained unaltered in the GA s-group. P-NA values in the GA o-group were lower than those of the GA s-group ( P < 0.001) following anaesthesia and surgery. Plasma adrenaline (P-A) increased in the LA- and the GA s-group and decreased in the GA o-group ( P < 0.001) following anaesthesia and surgery. In the LA-group P-A was similar before the skin incision and clamping but higher after declamping as compared to the GA s-group. Before the skin incision and thereafter P-A was lower in the GA o-group as compared to the other groups. There was a positive correlation between plasma catecholamines, on the one hand, and mean blood pressure and heart rate on the other. Two patients in the LA-, eight in the GA s- and seven in the GA o-group showed a hypotensive blood pressure reaction (SBP < 100 mmHg; LA vs. GA o, P < 0.01). Ten patients in the LA-group showed a hypertensive blood pressure reaction (SBD > 200; LA vs. GA s and GA o, P < 0.001 and P < 0.01, respectively). As judged from P-NA, blood pressure and heart rate, local anaesthesia is associated with activation of the sympathetic nervous system. On the other hand, general anaesthesia frequently induces marked hypotensive responses. Both types of anaesthesia thus have their disadvantages in patients with an increased risk for cardiovascular morbidity/mortality.