Objective: To evaluate the accuracy of the OMRON-MIT inflationary oscillometric device for blood pressure measurement in pregnancy and pre-eclampsia.
Design: Prospective observational study, using validation methods recommended by the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI).
Settings: Antenatal clinics and ward, Guy's Hospital, London.
Population: Normotensive pregnant women and those diagnosed with pre-eclampsia according to the definition of the International Society for the Study of Hypertension in Pregnancy.
Methods: Validation according to BHS protocol.
Main outcome measures: Proportion of readings within 5, 10 and 15 mmHg (absolute differences) between the automated device and two trained, blinded observers, according to the BHS and AAMI criteria.
Results: The OMRON-MIT achieved an overall BHS grade B for systolic and grade A for diastolic blood pressure measurement in both pregnancy and pre-eclampsia. The mean (SD) differences between the standard and the test device were -5 (7) mmHg for systolic and 2 (6) mmHg for diastolic blood pressure in pregnancy and -4 (6) mmHg for systolic and 2 (7) mmHg for diastolic blood pressure in pre-eclampsia. This device therefore fulfils the AAMI criteria.
Conclusion: The OMRON-MIT is the only automated oscillometric device that has proven to be accurate for blood pressure measurement in pre-eclampsia according to the BHS protocol in pregnancy. Inflationary oscillometry may correct the error associated with oscillometric devices in pre-eclampsia.