Cerebral Blood Flow during Early Cardiopulmonary Bypass in Man. Effect of Procaine in Cardioplegic Solutions

Summary

Cerebral blood flow (CBF), plasma Procaine concentrations, and somatosensory evoked Potentials (SSEP) were recorded in 2 groups of patients in whom either a high-procaine cardioplegic solution (Bretschneider's n = 29), or a low-procaine cardioplegic solution (St. Thomas', n = 13) was used. In the Bretschneider's group, marked changes in CBF occurred (p < 0.001). Mean CBF was 27 (range 18 to 51) ml/(100g · min) between sternotomy and the onset of extracorporeal circulation (ECO. A mean of 6 minutes after the onset of ECC, and before the administration of Bretschneider's cardioplegic solution, CBF increased to 39 ml/ (100g · min). After administration of the cardioplegic solution, CBF decreased significantly within the first 15 minutes, and then gradually increased to a mean of 68 (range 43 to 108) ml/(100g · min). Cerebral blood flow was 45 ml/ (100g · min) just after ECC was stopped. Marked plasma Procaine concentrations, up to 100 mg/l, were reached just after the infusion of Bretschneider's solution. The flow was significantly reduced (p < 0.015) in patients with plasma procaine ≥ 10 mg/l, when compared to patients with plasma procaine values < 10 mg/l.

In the St. Thomas' cardioplegic solution group the same reduction in CBF did not occur (p < 0.02). Despite the depressant effect of Procaine on CBF in the Bretschneider group, a consistent brain hyperperfusion was observed in all patients during hypothermic ECC if their blood pressure was sufficient to produce hyperemia.

In rats (n = 6), during normothermia without extracorporeal circulation, the effect of procaine was much more pronounced. The CBF fell from a mean resting level of 108 ml/(100g · min) to 68 and 54 ml/(100g · min) after 15 and 35 minutes, respectively, of continuous infusion of Bretschneider's solution. The flow returned to the resting level about 40 minutes after termination of the infusion.

Key words

Cerebral blood flow (CBF) - Cardiac surgery - Cardioplegic arrest - Bretschneider's solution - St. Thomas' solution