Blood Pressure Self-Measurement in the Obstetric Waiting Room

Introduction

Blood pressure (BP) self-measurement (BPSM) is important in the monitoring of pregnant women suffering from diabetes. ^{1 –3} Pregnant diabetics hold an increased risk of harm to their fetus due to the complications experienced during pregnancy. In addition, fetal and maternal morbidity and mortality rates are higher than normal when pregnant women have a diastolic pressure of 110 mm Hg or higher during the first trimester. ⁴ In the waiting room at the obstetrics department of Aarhus University Hospital (Aarhus, Denmark), pregnant diabetic patients are required to self-measure their BP before consultation. This is done order in to avoid the “white coat effect” as well as allowing for more frequent measurements without straining staff resources. ⁵ Only pregnant diabetic patients are required to self-measure because of their frequent number of visits, up to 19 visits during a pregnancy, and the importance for frequent monitoring of their BP. Two BPSM devices (Microlife BP A100; Microlife AG, Widnau, Switzerland) are available in the waiting room for this purpose.

The BPSM process requires the patient to follow a range of recommendations from the Danish Hypertension Society to ensure valid results. Existing BP devices are not capable of sensing incorrect usage, ⁵ and as only measurements following the recommendations are considered reliable, ^{1 –3} this could lead to potential misdiagnosis. ^6,7

The aim of this study was to investigate the current use of BPSM in the waiting room in order to identify challenges that could influence the resulting data quality. Also, we wanted to investigate the potential for addressing these challenges with e-health and telemedicine technology.

Subjects and Methods

We planned a study design divided into two phases. In the first phase, we interviewed department staff on current BPSM praxis, including instructions and training provided to the pregnant women on how to self-measure in the waiting room. In the second phase, we performed an observational descriptive study in the waiting room, observing the self-measurement behavior of the pregnant women anonymously during a 4-week period. The investigators acted as visitors without identification, relying on a log book for noting observations to avoid biasing patient behavior. The log book included a check list of correct patient adherence to the Danish Hypertension Society recommendations ⁸ : “Was the patient talking during measurement?,” “Were the patient's legs uncrossed?,” “Did the patient rest the required 5 min before measurement?,” “Did the patient use the correct cuff size?,” “Was the measurement arm supported?,” and “Did the patient sit with back supported during measurement?” Also, the checklist facilitated noting the number of measurements taken by each patient.

Results

In the first phase, we found that patients are instructed by the department nurses to follow the recommendations as formulated by the Danish Hypertension Society ⁸ with the exception that patients need only take a single measurement in the waiting room. Danish Hypertension Society recommendations state that at least three measurements are necessary. ⁸

In the second phase, we found that none of the 81 participants adhered to all six investigated recommendations. Around a quarter (26%) adhered to five of the six recommendations. Around a third followed four recommendations (37%), a fifth followed three (21%), 12% followed two, and 3% followed one recommendation. In Table 1, we present the detailed observations of adherence to the recommendations.

Discussion

We found that all patients only performed a single BP measurement, as instructed by staff, which is not adequate for obtaining a reliable BP reading. ^{8 –10} Thus, the instructions given by the staff should be corrected to require exactly three measurements. Also, we observed inadequate patient adherence to the recommendations, which also constitutes a challenge to the data quality and measurement reliability. ^3,9,11 Using existing BP devices does not support the detection of such nonadherent behavior. As a consequence, the quality of the data cannot be validated by the staff other than by relying on direct observation and intervention as needed. This is, however, not a cost-effective or feasible solution taking into consideration the available staff resources, which are unlikely to increase in the future. ⁵

Thus, we found a strong indication that the current praxis and technology are not adequate for providing reliable BP measurements. Instead, we suggest introducing context-aware e-health technology in the waiting room recording the BP of patients in combination with relevant context parameters relating to patients' adherence to the recommendations. These additional context parameters could include measuring rest time before measurement and whether the patient is talking during measurement, the back is supported, and the legs are crossed. ¹² This knowledge would alert the medical staff to any nonadherent patients, thus pinpointing them for additional training and instructions using a suitable client device. Also, improved guidance for patients while self-measuring (e.g., correcting any nonadherent behavior in real time rather than retrospectively) could be relevant to investigate further. Alternatively, patients could be provided with telemedicine and e-health equipment for home use. However, this approach requires more equipment and incurs higher costs and more administrative overhead than current praxis.

Several studies have investigated patients' ability to correctly self-report home measurements for telemedicine use. ^{13 –15} These include three related studies in which, in total, 98 patients were equipped with home BP devices. The patients were not told that the devices had memory for storing readings. After a period of self-monitoring, paper records and device memory values were compared. In total, more than half the patients had either omitted or fabricated readings, indicating unacceptable levels of reporting bias. A later study investigated 161 patients' ability to accurately report self-measured BP data using a Web solution and a BP device. ¹⁶ The study compared the self-reported data from the home with the data stored in the device memory. The authors found that around 16% of the reported data deviated from the actual data stored in the device memory. Results from the four studies thus indicate a clear challenge with BPSM in the unsupervised setting with regard to patients' ability to accurately report self-measured data. The present study did not investigate self-reporting. Instead, we focused on patient adherence to the recommendations, which has not yet been adequately investigated.

In a recent study, our group investigated current clinical praxis and patient understanding of the guidelines for BPSM. ⁵ Results indicated general low patient-awareness of the recommendations for BPSM and of the importance of this in order to obtain valid and reliable measurements. The interviewed healthcare professionals acknowledged the identified challenges and the importance of following the recommendations but reported being unable to validate self-measured data with existing technology. ⁵

Conclusions

Through anonymous and unobtrusive observations of 81 patients, we found clear indications that current methods for BPSM are facing several challenges regarding the reliability of unsupervised BP measurements. Existing BP devices are not capable of addressing these challenges. Instead, we should investigate the potential for designing novel context-aware e-health and telemedicine-based clinical support systems that are able to pinpoint nonadherent behavior and alert the staff accordingly as well as to guide the patients during measurements.