CARDIOVASCULAR AND CEREBROVASCULAR EFFECTS OF THE APPLIED VALSALVA MANEUVER IN ANESTHETIZED NEUROSURGICAL PATIENTS

We examined the effects of Valsalva's manoeuvre and its four phases on heart rate, central venous pressure (CVP), mean arterial pressure (MA P), cerebral perfusion pressure (CPP), and laser Doppler cerebellar co rtical blood flow (CBF). Brief Valsalva manoeuvres increased CVP and m arkedly decreased MAP. Cerebral perfusion pressure significantly (P le ss-than-or-equal-to 0.01, Dunnett's test) decreased during phases 2 an d 3 of the Valsalva manoeuvre. Cortical blood flow closely paralleled CPP; CBF decreased to 59% of control during phase 2 and to 57% of cont rol during phase 3 of the Valsalva manoeuvre. The MAP, CPP, and CBF al l returned to baseline levels during phase 4 (the overshoot phase) of the Valsalva manoeuvre, and were not significantly greater than contro l. No autoregulatory change in cerebrovascular resistance occurred thr oughout the Valsalva manoeuvre. These results suggest that brief Valsa lva manoeuvres, as employed during neurosurgical procedures, mainly co nfirm venous haemostasis, but must be used cautiously due to the marke d haemodynamic changes.