Invasive versus non-invasive monitoring of acute severe hypertension in women with pre-eclampsia

ObjectiveTo compare the accuracy of two non-invasive methods of blood-pressure measurement with intra-arterial measurement in women with pre-eclampsia and acute severe hypertension.MethodsThis descriptive, cross-sectional study prospectively enrolled 23 women with pre-eclampsia and acute severe hypertension for continuous intra-arterial blood-pressure monitoring. Simultaneous monitoring was performed with a manual and an automated, non-invasive device during episodes of severe hypertension. The paired T-test was used to compare measured values. The accuracy of a MAP ⩾ 125 mmHg in detecting a systolic blood pressure ⩾ 160 mmHg was determined.ResultsThere was a weak correlation between intra-arterial and automated as well as intra-arterial and manual systolic values (r = 0.34, p < 0.01; r = 0.41, p < 0.00, respectively). Better correlation was found amongst diastolic values. The differences between the mean intra-arterial (94 ± 11 mmHg) and automated (96 ± 12 mmHg) diastolic values as well as intra-arterial and manual diastolic measurements (94 ± 14 mmHg) were not significant (p = 0.20, 0.65, respectively). A mean arterial pressure ⩾ 125 mmHg was not accurate in detecting a systolic value ⩾ 160 mmHg, with low sensitivities (17.2–35.9%) and specificities (0–50%) for all three methods.ConclusionsWhen compared to intra-arterial monitoring, the automated and manual methods showed weak correlation with systolic but better correlation with diastolic values. A mean arterial pressure ⩾ 125 mmHg was not accurate in detecting systolic peaks. When protection against cerebral haemorrhage is paramount, intra-arterial measurement of systolic values is best.