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

Abstract

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 less than 0.001). Mean CBF was 27 (range 18 to 51) ml/(100 g X min) between sternotomy and the onset of extracorporeal circulation (ECC). A mean of 6 minutes after the onset of ECC, and before the administration of Bretschneider's cardioplegic solution, CBF increased to 39 ml/(100 g X 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/(100 g X min). Cerebral blood flow was 45 ml/(100 g X 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 less than 0.015) in patients with plasma procaine greater than or equal to 10 mg/l, when compared to patients with plasma procaine values less than 10 mg/l. In the St. Thomas' cardioplegic solution group the same reduction in CBF did not occur (p less than 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/(100 g X min) to 68 and 54 ml/(100 g X 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.

Cerebral blood flow during cardiopulmonary bypass in man: effect of arterial filtration.

“…The effect is transient, however, and is noticed only during hypothermic bypass, just after the infusion of the cardioplegic solution. 8 Given that arterial filters of 20 or 40 microns slightly reduced cerebral blood flow but did not prevent brain hyperaemia and filters of even smaller pore size would probably result in too much blood trauma, some other measure is needed to reduce cerebral blood flow. Management of PCo2 could be a simpk way of doing this, and hence appreciably reduce the amount of emboli which could be trapped in the brain capillaries.…”

“…A new index of the quality of surgery is emerging, based on psychometric analysis of the extent to which complex mental functioning is preserved in the early postoperative period, combined with more quantitative methods, such as analysis of spinal fluid intracellular markers1 -3 and measurements of cerebral blood flow during and after cardiac surgery. [4][5][6][7][8] In our earlier studies of cerebral blood flow during cardiac surgery we found a consistent hyperperfusion of the brain during cardiopulmonary bypass6 -8 and a diffusely reduced regional cerebral blood flow after surgery,5 the most reasonable explanation being a diffuse microvascular blockage of microembolic origin.…”

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