Cardiovascular and cerebrovascular effects of the applied Valsalva manoeuvre in anaesthetized neurosurgical patients

We examined the effects of Valsalva's manoeuvre and its four phases on heart rate, central venous pressure (CVP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), and laser Doppler cerebellar cortical blood flow (CBF). Brief Valsalva manoeuvres increased CVP and markedly decreased MAP. Cerebral perfusion pressure significantly (P≤0.01, Dunnett's test) decreased during phases 2 and 3 of the Valsalva manoeuvre. Cortical blood flow closely paralleled CPP; CBF decreased to 59% of control during phase 2 and to 57% of control during phase 3 of the Valsalva manoeuvre. The MAP, CPP, and CBF all returned to baseline levels during phase 4 (the overshoot phase) of the Valsalva manoeuvre, and were not significantly greater than control. No autoregulatory change in cerebrovascular resistance occurred throughout the Valsalva manoeuvre. These results suggest that brief Valsalva manoeuvres, as employed during neurosurgical procedures, mainly confirm venous haemostasis, but must be used cautiously due to the marked haemodynamic changes.