Cerebral haemodynamics in pregnancy and pre-eclampsia as assessed by transcranial Doppler ultrasonography

Background. Altered cerebral circulation, as reported duringnormal pregnancy, and in patients with pre-eclampsia, can beassociated with changes in cerebral vascular reactivity and/orcerebral autoregulation. The aim of our study was to performa comparative assessment of cerebral haemodynamics, includingvascular reactivity and autoregulation, in pre-eclamptic patients,healthy pregnant women, and healthy non-pregnant women. Methods. Thirty patients with pre-eclampsia were recruited.Age- and height-matched healthy pregnant (n=30) and non-pregnantcontrol (n=30) groups were also recruited. Monitoring includedtranscranial Doppler ultrasonography, end-tidal carbon dioxideand non-invasive arterial pressure measurement. Cerebral autoregulationwas assessed by performing the transient hyperaemic response(THR) test. The cerebrovascular reactivity to carbon dioxide(CRCO₂) was assessed by measuring middle cerebral artery bloodflow velocity (MCAFV) after induced changes in end-tidal carbondioxide. Estimated cerebral perfusion pressure (eCPP) and criticalclosing pressure (CrCP) were calculated using established formulae.Statistical analysis included ANOVA with Tukey’s pairwisecomparisons. Results. Mean arterial pressure (MAP) was increased in pre-eclampsia(P<0.05). Mean MCAFV was lower in healthy pregnancy (P<0.05),but in pre-eclampsia it was similar to the non- pregnant group.When compared with the non-pregnant group, mean eCPP was higherin the healthy pregnant and pre-eclamptic groups (P<0.05).There were no meaningful differences in cerebral autoregulationor CRCO₂. Conclusions. Healthy pregnancy increases eCPP, presumably bydecreasing CrCP. In pre-eclampsia, eCPP is maintained at thesame level as in healthy pregnancy despite an increased MAP.Pre-eclampsia has no significant effect on cerebral autoregulationor CRCO₂. Br J Anaesth 2002; 89: 687–92