Evaluation of cerebral perfusion pressure changes in laboring women: effects of epidural anesthesia.

Abstract

To compare the effect of epidural anesthesia on cerebral perfusion pressure in laboring women. Maternal cerebral blood flow velocity was assessed in seven laboring patients with continuous epidural anesthesia and 15 without, using transcranial Doppler. Maternal cerebral blood flow velocity was assessed during the first stage at the trough of a contraction, at the peak of a contraction and at the second stage during pushing over the course of four contractions. Calculated estimated cerebral perfusion pressure: eCPP = Vmean/(Vmean - Vdiastolic) x (mean BP - diastolic BP), where V is velocity and BP is blood pressure; modified from Aaslid and colleagues. An index of cerebrovascular resistance, the resistance area product, was calculated: RAP = mean BP/mean velocity. We calculated an index of cerebral blood flow (cerebral blood flow index): CBF index = eCPP/RAP. In non-epidural patients, the eCPP fell significantly at the peak of a contraction and during pushing. Cerebrovascular resistance, RAP, rose significantly during the peak of a contraction, although cerebral blood flow did not change. In patients undergoing epidural anesthesia, the stages of labor had no significant effect on eCPP or RAP; however, these values were lower than those in patients without epidural anesthesia. The epidural group had a lower eCPP and RAP and cerebral blood flow index compared to the non-epidural group. In the non-epidural group, the mean arterial pressure was higher in all stages of labor with a trend towards an increase in eCPP and cerebral blood flow index.