AbstractsMedical & Health Science

Thesis (MMed (Obstetrics and Gynaecology)) – University of Stellenbosch, 2010. ENGLISH ABSTRACT: OBJECTIVE: The aim of this study was to compare the accuracy of non-invasive blood pressure measurements, using automated and manual devices, against invasive intra-arterial blood pressure measurements in patients with pre-eclampsia, during a hypertensive blood pressure peak. STUDY DESIGN: In this prospective study, women admitted to the Obstetrics Critical Care Unit, with confirmed pre-eclampsia and acute severe hypertension, who had an intra-arterial line in situ, were asked to participate. During an intra-arterial blood pressure peak, both an automated oscillometric and a blinded manual aneroid sphygmomanometric blood pressure was recorded. These two methods of blood pressure measurements were compared to intra-arterial blood pressure measurements. The accuracy of a mean arterial pressure (MAP) ≥ 125mmHg in detecting a systolic blood pressure (SBP) ≥ 160mmHg, using all three methods, was also determined. RESULTS: There was poor correlation between intra-arterial SBP and automated and manual SBP (r = 0.34, p < 0.01; r = 0.41, p < 0.01 respectively). The mean differences between automated and manual SBP compared to the intra-arterial SBP was 24 ± 17mmHg (p < 0.01) and 20 ± 15 mmHg (p < 0.01) respectively. There was better correlation between intra-arterial diastolic blood pressure (DBP) and automated and manual DBP (r = 0.61, p < 0.01; r = 0.59, p < 0.01 respectively). The mean differences of the automated and manual DBP was not statistically significant when compared to the intra-arterial DBP. There was poor correlation between the intra-arterial MAP and the automated MAP (r = 0.44, p < 0.01) and good correlation with the manual MAP (r = 0.56, p < 0.01). The mean differences of the automated and manual MAP were statistically significant (5 ± 13mmHg, p < 0.01; 8 ± 11mmHg, p < 0.01 respectively). The sensitivity of automated and manual methods in detecting a SBP ≥ 160mmHg was 23.4% and 37.5% respectively. A MAP ≥ 125mmHg in detecting a SBP ≥ 160mmHg, when using intra-arterial, automated and manual methods of blood pressure measurements showed low sensitivity (35.9%, 21.9% and 17.2% respectively). CONCLUSION: This study demonstrated that both the automated and manual methods of blood pressure measurements were not an accurate measure of the true systolic intra-arterial blood pressure, when managing pre-eclamptic patients with acute severe hypertension. In such situations, intra-arterial blood pressure monitoring should be used when possible. When this is not possible, manual aneroid sphygmomanometry is recommended. Underestimating blood pressure, particularly SBP, may lead to severe maternal morbidity and mortality. AFRIKAANSE OPSOMMING: DOELWIT: Die doel van hierdie studie is om die akuraatheid van nie invasiewe bloeddruk metings, wanneer geneem met outomatiese en manuele aparate, te vergelyk met intra-arteriele bloed druk metings in pasiente met pre-eklampsie, gedurende ‘n hipertensiewe bloeddruk piek. STUDIE…