Aidan Halligan

Automated, ambulatory, or conventional blood pressure measurement in pregnancy : Which is the better predictor of severe hypertension?

Abstract OBJECTIVES: Our purpose was to investigate the benefit, if any, of automated blood pressure monitoring over obstetric day unit conventional blood pressure measurement in the assessment of hypertensive pregnancies. STUDY DESIGN: A prospective, observational study was carried out in two large teaching hospitals. Three hundred and forty-eight women with a confirmed clinic blood pressure of at least 140/90 mm Hg were recruited. Conventional blood pressure measurements (≤5) were obtained on the day unit and simultaneously an ambulatory blood pressure monitor was applied for 24 hours. The predictive ability of day unit assessment (blood pressure >140/90 mm Hg) and automated blood pressure monitoring (blood pressure >130/85 mm Hg) was compared. Principal outcome measures included the occurrence of severe hypertension (>160/110 mm Hg) and proteinuria (>500 mg or 2+) within (a) 2 weeks and (b) the remainder of the pregnancy. Thompsons method was used to compare sensitivity and specificity of the day unit blood pressure and automated blood pressure monitoring. RESULTS: Three hundred and forty-eight women were recruited to the study. The comparison between automated blood pressure monitoring and conventional blood pressure measurement for both sensitivity and specificity for systolic and diastolic blood pressure revealed increased sensitivity and decreased specificity with automated blood pressure monitoring for all principal outcomes except development of proteinuria for systolic blood pressure. Sensitivity for the outcomes was increased with automated blood pressure monitoring by between 14% and 27% for systolic blood pressure and between 7% and 39% for diastolic blood pressure, with the greatest improvement seen for the development of severe hypertension within 2 weeks of assessment. CONCLUSIONS: In the assessment of hypertensive pregnancies, automated blood pressure measurement was a significantly better predictor (compared with conventional day unit assessment) for the development of severe hypertension within 2 weeks of assessment for both systolic and diastolic blood pressure. (Am J Obstet Gynecol 1998;178:521-6.)

Comparison of auscultatory and oscillometric automated blood pressure monitors in the setting of preeclampsia

OBJECTIVE The aim of this study was to compare the accuracy of 2 automated blood pressure monitors against mercury sphygmomanometry and intra-arterial blood pressure determination in women with preeclampsia. STUDY DESIGN The auscultatory and oscillometric monitors were compared with mercury sphygmomanometry according to the British Hypertension Society protocol and criteria of the Association for the Advancement of Medical Instrumentation in a group of 30 women with proteinuric preeclampsia. In addition both monitors were compared with intra-arterial blood pressure measurements in a group of 6 women with severe preeclampsia. The mean (+/- SD) of the differences was calculated and a paired t test was used to compare values obtained with each monitor with intra-arterial measurements. RESULTS Compared with mercury sphygmomanometry the auscultatory QuietTrak monitor markedly underestimated systolic and diastolic blood pressure by 13 +/- 15 mm Hg. The oscillometric SpaceLabs 90207 monitor also underestimated systolic pressure by 10 +/- 10 mm Hg and diastolic pressure by 8 +/- 7 mm Hg. According to the British Hypertension Society grading criteria both monitors achieved the lowest grade (D) for recording systolic and diastolic pressure. The 2 monitors also did not meet the accuracy criteria stipulated by the Association for the Advancement of Medical Instrumentation. Compared with intra-arterial readings the SpaceLabs monitor significantly underestimated systolic and mean arterial pressures (by 19 and 7 mm Hg, respectively, P <. 01). The QuietTrak monitor significantly underestimated systolic, diastolic, and mean arterial pressures (by 25 mm Hg, P <.05, 18 mm Hg, P <.01, and 20 mm Hg, P <.01, respectively). CONCLUSION Neither monitor can be recommended for clinical use in women with proteinuric preeclampsia.

Optimal bedside urinalysis for the detection of proteinuria in hypertensive pregnancy: a study of diagnostic accuracy

Objective  To compare semi‐quantitative visual and automated methods of urine testing with fully quantitative point of care urinalysis for the detection of significant proteinuria (0.3 g/24 hours) in pregnancy complicated by hypertension.

Accuracy of oscillometric blood pressure monitoring in pregnancy and pre‐eclampsia

Objective To assess the accuracy of the Omron HEM 705 CP oscillometric device for the measurement of blood pressure in pregnancy and pre‐eclampsia.

Hidden errors of aneroid sphygmomanometers.

BackgroundMeasurement of blood pressure remains the most commonly performed screening test in medical practice. With the likely removal of mercury sphygmomanometers from the workplace alternative devices are required. Of these the aneroid sphygmomanometer is popular both in the community and hospital setting. We investigated the accuracy of all the aneroid and mercury sphygmomanometers during dynamic calibration within a tertiary referral maternity hospital. MethodsWe compared the accuracy of 39 aneroid and 36 mercury sphygmomanometers to a recently calibrated and serviced mercury sphygmomanometer (the accepted gold standard). All devices were in current clinical use. Using three blinded, trained observers, 30 different pressures were checked throughout the pressure range following British Hypertension Society protocol guidelines. ResultsOnly 31 (86%) of the mercury devices and 36 (92%) of the aneroid devices were in adequate working condition and suitable for analysis. Significantly more aneroid devices had systematic errors of > 5 mmHg (19 versus 3%, P < 0.05). Fifty percent of aneroid devices had at least one reading > 10 mmHg out compared to only 10% of mercury devices (chi square programme). ConclusionsAneroid sphygmomanometers in apparent good working order are inaccurate compared to mercury devices. Some of these faults can only be detected during dynamic testing. To minimize the risk of erroneous blood pressure recording, aneroid devices should be regularly checked for accuracy using dynamic calibration methods as recommended in validation protocols.

The role of observer error in antenatal dipstick proteinuria analysis

Objective To determine the role of inter–observer error and the influence of training upon dipstick urine analysis.

Ambulatory Blood Pressure Measurement in Pregnancy: the Current State of the Art

Blood pressure measurement is one of the most frequently used screening tests in pregnancy. However, conventional blood pressure measurement has several shortcomings; it provides a measurement that represents only a fraction of the 24-h blood pressure profile, usually under circumstances that may have a pressor effect, and the technique is fraught with potential errors. In the nonpregnant population the development of devices capable of accurately measuring 24-h blood pressure noninvasively is proving valuable in predicting the cardiovascular complications of hypertension. It is likely that this technique will also prove useful in pregnancy. Validation in pregnancy of such monitoring techniques should precede any widespread application. Reference values using oscillometric monitors are now available for 24-h ambulatory blood pressure measurement in pregnancy. Provisional data suggest that ambulatory blood pressure measurement could overcome the large sampling, measurement, and “white coat hypertension phe...

Oscillometric blood pressure measurements in severe pre‐eclampsia: validation of the SpaceLabs 90207

* Andrew Shennan Lecturer (Obstetrics and Gynaecology), ** Aidan Halligan Senior Lecturer (Obstetrics and Gynaecology), * Manish Gupta Medical Student, ** David Taylor Professor (Obstetrics and Gynaecology), * Michael de Swiet Consultant Physician * Institute of Obstetrics and Gynaecology, Royal Postgraduate Medical School, Queen Charlottes and Chelsea Hospital, London; ** Department of Obstetrics and Gynaecology, University of Leicester, Leicester Royal Infirmary

Urine protein estimation in hypertensive pregnancy: which thresholds and laboratory assay best predict clinical outcome?

Objective. To determine what threshold for proteinuria could best predict clinical outcome and whether this threshold could be applied universally to any biochemical assay. Design. A prospective observational study of hypertensive pregnancies referred for further assessment after in a UK University hospital (n = 197). Twenty-four hour urine protein was measured by two different assays [benzethonium chloride assay (BCA) and Bradford assay]. The differences between the two assays were calculated from Receiver Operating Characteristic (ROC) curves. Commonly used thresholds for defining preeclampsia (0.3 and 0.5 g/24 hours) were explored for both assays for the prediction of adverse clinical outcomes (severe hypertension, Birthweight < 10th percentile, preterm delivery, and a composite biochemical/haematological derangement). Results. The two assays are not equivalent. The prevalence of > 300 mg/24 hour proteinuria and, hence, the prevalence of preeclampsia differed between the two assays. ROC curve analysis demonstrates that the two assays are similar in terms of overall performance as predictive tests. However the threshold of 300 mg/24 hours performs poorly as a predictor of clinical risk. Likelihood ratios (LR) for the BCA at the 300 mg/L threshold for each clinical outcome do not achieve statistical significance. At the 500 mg/L threshold, the LR + for the BCA assay does achieve statistical significance for severe hypertension (LR + : 1.51 95% CI 0.99–2.28) and for birthweight < 10th percentile (LR + : 1.72 95% CI 1.11–2.66). For the Bradford assay at the 300 mg/24 hour threshold, the LR + does achieve statistical significance for birthweight < 10th percentile (LR + : 1.71 95% CI 1.41–4.31). However, at the 500 mg/24 hour threshold, the LR + is significant for severe hypertension (LR + : 2.15 95% CI 1.07–4.34), birthweight < 10th percentile (LR + : 2.79 95% CI 1.4–5.54) and biochemical disease (LR + : 2.47 95% CI 1.22–5.01). Conclusions. This study suggests that thresholds for proteinuria need to be higher (possibly ≥ 0.5 g/24 hours) and there is the need for a “gold standard” proteinuria assay against which all other measures of quantification can be assessed.

DIPSTICK PROTEINURIA : CAVEAT EMPTOR

Apart from the measurement of blood pressure, analysis of urine by dipstick for proteinuria is the most commonly performed antenatal screening test. The presence of proteinuria is central to the diagnosis of pre-eclampsia in a hypertensive pregnancy; is an important marker of the seventy or progression of the disease; and is a component of classification systems for hypertensive pregnancy. The classification of hypertensive disorders during pregnancy is an obstacle to research in this life threatening condition’-’. Integral to the classification is the definition of proteinuria and hypertension. Although the definition of hypertension within the context of pregnancy has long been the subject of controversy, for many obstetricians the detection of significant proteinuria in a hypertensive pregnancy is regarded as a sinister finding. In pregnant women with mild chronic hypertension but no proteinuria, the outcome of pregnancy is similar to non-hypertensive pregnant women4. However, hypertension with proteinuria is associated with poor fetal outcome, particularly when they occur remote from term. It is associated with an increased rate of small for gestational age pregnancies, perinatal mortality and poorer maternal prognosis5-10. Of women with chronic hypertension who also developed proteinuria, 10%-20% had a poor pregnancy outcome, with a 10% incidence of abruptio placentae, a 33% incidence of intrauterine growth restriction, and a perinatal mortality rate of 24%4. When severe hypertension is associated with significant proteinuria (>5 g in 24 h) delivery is usually indicated within 2-3 weeks6.