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This prospective observational study aimed to identify at presentation the maternal hemodynamic and demographic variables associated with a therapeutic response to oral labetalol and to use these variables to develop a prediction model to anticipate the response to labetalol monotherapy in women with hypertension. It was set at a maternity unit in a UK teaching hospital. Maternal demographic data from 50 pregnant women, presenting with hypertension between January and August 2013, was collected and blood pressure measured with a device validated for pregnancy and pre-eclampsia. Maternal haemodynamics were assessed with a bioreactance monitor. Participants were commenced on oral labetalol, and reviewed until delivery and discharge home. Logistic regression analysis was performed to assess the prediction of response to labetalol according to the maternal demographic and hemodynamic variables. Main outcome measures were the response to labetalol monotherapy up to delivery and discharge home, defined as sustained blood pressure control <140/90, and the rates of severe hypertension. Thirty-seven women (74%) had their blood pressure well controlled with labetalol monotherapy, 13 (26%) failed to achieve control with labetalol alone, of whom 9 developed severe hypertension. Multivariate logistic regression showed that heart rate, ethnicity and stroke volume index were independent predictors of the response to labetalol. The predictive accuracy of the model was 96% (95% confidence interval (CI) 86-99%). Maternal demographics and haemodynamics are potent predictors for the response to labetalol, and these parameters may guide therapy to enable effective blood pressure control and a lowering of severe hypertension rates.

Mercury-independent devices are increasingly being used in clinical practice as mercury will soon be removed from clinical use as a result of environmental, health and safety concerns. The aim of this study was to evaluate the accuracy of a portable aneroid device in an adult population at high altitude by following the part of the protocol of the British Hypertension Society regarding comparison between device and observer. We examined 10 subjects in Cerro de Pasco, Peru, which is situated 4370 m above sea level. The aneroid device was initially calibrated at both high altitude and at sea level to ensure optimal function. Validation of the device was undertaken at high altitude by connecting it in parallel to two mercury sphygmomanometers. Eleven sequential same-arm measurements were taken from each subject by two trained observers, alternating between mercury sphygmomanometry and the aneroid device. Simultaneous mercury readings were also recorded for additional analysis. During calibration, all 60 comparisons between the aneroid and mercury sphygmomanometers were within 3 mm Hg both at sea level and at high altitude. At validation, the device achieved an A grade for both systolic and diastolic pressures and also fulfilled the requirements of the Association for the Advancement of Medical Instrumentation. The mean and standard deviation for systolic and diastolic pressures, respectively, were -1.32 (4.3) mm Hg and 3.7 (4.7) mm Hg in sequential analysis and -0.7 (2.6) mm Hg and -3.3 (2.7) mm Hg in simultaneous analysis. We conclude that the Riester-Exacta portable aneroid device can be recommended for use in an adult population at high altitude.