Accurate Measurement of Blood Pressure in Pregnancy

Abstract

Hypertensive disorders are the most common medical complication of pregnancy and a major cause of neonatal and maternal morbidity and mortality in the UK and worldwide. Accurate recording of blood pressure measurement (BPM) is critical to ensure hypertension in pregnancy is correctly diagnosed and managed. Defective equipment and a failure to follow the correct BPM technique can lead to inaccurate readings. Studies have found this to be the case in both primary care and hospital settings. However, there is limited research evidence regards the condition of BPM equipment and BPM practice of health professionals working in maternity services.This study is unique in that it encompasses an audit of BPM equipment, an assessment of BPM practice among health professionals and the impact of continuing education within three U.K. maternity units. This was a descriptive evaluation study that included a baseline audit of 165 blood pressure devices and a practice survey questionnaire distributed to 436 health professionals. In addition, 57 observations of staff conducting BPMs were undertaken. This was followed by an intervention in the form of an education programme delivered to 163 members of staff. The impact of the intervention upon equipment and matched pairs of health professionals was evaluated by a follow up equipment audit of 119 blood pressure devices and practice survey of 46 members of staff who completed the education programme and 32 who did not. Data were analysed using non-parametric statistic tools that included Chi-Square, McNemar, Spearman, Mann-Whitney-U and Wilcoxon tests.The baseline survey found that out of 165 BP devices, 89% (148) had no indication of ever being serviced, 21% (28) failed calibration testing and that only 3% (5) devices were found to have no component faults. Out of the 22 automated devices surveyed, none had been independently validated as suitable for use on pregnant women. There was a lack of availability of large cuffs located across all three maternity units of the recommended size. The observed practice of 57 staff taking BPM did not comply with current BPM guidelines. The baseline practice survey findings revealed that 156 (63%) of the 246 respondents did not use the correct rate of deflation, 103 (42%) incorrectly used Korotkoff 4 for diastolic pressure and 188 (76%) could not correctly identify the effect of arm position on BP readings. Evaluation of the impact of the education programme upon the working condition of BP equipment and practice of BPM revealed some positive effects with a significant changes in overall practice questionnaire scores (before vs. after P=<0.001) in participants who attended the education programme compared to those who did not attend the education programme (P=0.982). Of the 119 BPM devices examined in the follow up survey there was a 13% increase in the number of devices that had evidence of servicing and a 6% increase in the number that passed calibration testing.Thus, the study identified that the accuracy of BP measuring equipment was questionable. Also, there were variances with the method of BPM technique and a lack of compliance with recommended guidelines on how BP should be measured. Updating staff on how to conduct an accurate BPM and raising awareness of the factors that affect accurate BPM has the potential to reduce the risk of obtaining an inaccurate BPM due to faulty equipment or incorrect technique. Quality improvement initiatives around the care of women with hypertensive disorders in pregnancy need to incorporate performance assessment of staff BPM technique and BP equipment accuracy assessment. Equipment should be in full working order, regularly serviced and maintained and defective equipment removed. Health professionals conducting BPM on pregnant women need to ensure that they access regular and appropriate updating on the recommended technique for BPM and have knowledge around servicing, calibration requirements, and validation requirements of BP devices. Perhaps most important of all is not to take for granted their competency in this basic but essential clinical skill.