Accuracy Assessment of an Automatic Blood Pressure Measurement Device in Pregnant Women

The purpose of the study is to help make a lower cost automatic blood pressure monitor device for diagnosis and monitoring of pre-eclampsia in pregnant women, where automatic blood pressure monitoring is limited or not available. The study will compare this low cost device to a commercially available system used for pre-eclamptic women in many United States hospitals that the investigators will be bringing to Malawi as a part of this study. The team hopes to show that this lower cost blood pressure machine works well and can help women with pre-eclampsia. The study also aims to see if this machine is easy for the nurse to use. 70 pregnant women who are either at-risk or diagnosed with pre-eclampsia will be enrolled at University of Texas Health Science Center Houston. Patient arm circumference will be measured with measurement tape. They will be seated upright in a comfortable chair with arm at heart level and an arm blood pressure cuff from either the automatic blood pressure monitor or a manual sphygmomanometer will be placed on the left arm. The cuff will be inflated and then deflated until measurement concludes. Heart rate will be measured with tactile arterial palpation.The process will be repeated for a total of up to nine measurements, alternating between measurements with the automatic blood pressure monitor and the manual sphygmomanometer. There will be a waiting period of 45-60 seconds between each measurement. The results of this study will help researchers understand the performance and usability of this device in Malawi and help decide if any design changes are needed.

The research team has developed an automatic blood pressure monitor to be used for the monitoring and diagnosis of pre-eclampsia in pregnant women, particularly in low-resource settings where current monitoring is limited. This study aims to evaluate the accuracy of the device's blood pressure measurements in pregnant and pre-eclamptic women. This device must be evaluated with the above described population because blood pressure measurement devices are known to perform differently in pregnant and pre-eclamptic women than in normal healthy adults. This study will take place at the University of Texas Health Science Center (UTHSC) where up to 70 subjects will be recruited to participate during their regularly scheduled antenatal care checkups. The Patient arm circumference will be measured with measurement tape. The Patient will be seated upright in a comfortable chair with arm at heart level. An arm blood pressure cuff from either the automatic blood pressure monitor or a manual sphygmomanometer will be placed on the left arm of the patient over the brachial artery. Cuff will be inflated to ~200 mmHg and then deflated until measurement concludes. Heart rate will be measured with Tactile Arterial Palpation. Steps 3-4 will be repeated for a total of up to nine measurements, alternating between measurements with the automatic blood pressure monitor and the manual sphygmomanometer. There will be a waiting period of 45-60 seconds between each measurement.

All subjects will have blood pressure measured by both the research device (Sphygmo) and the commercially available device. All clinical decisions will be made using measurements from the commercially available device.

A team of engineers from Rice University has recently developed Sphygmo, an ambulatory, low-cost blood pressure monitor for use in the diagnosis and management of pre-eclampsia in low-resource hospitals

Mean difference of systolic and diastolic blood pressures between Sphygmo blood pressure measurements and measurements from the gold standard sphygmomanometer.

Blood pressure was measured an average of 9 times for each participant and the average of these measurements was recorded. Each measurement period lasted approximately 30-45 minutes

Percent of Sphygmo Readings That Were Within 5mmHg, 10mmHg, and 15mmHg of the Readings by the Gold Standard Sphygmomanometer.

The British Hypertension society defines a specific criteria for the accuracy of a sphygmomanometer. Devices are graded according to the cumulative percentage of readings that have an absolute difference between the more favorable observer's mercury sphygmomanometer readings and the test device of < 5 mmHg, < 10 mmHg, and < 15 mmHg. A letter grade of "A" requires that over 60%, 85%, and 95% were achieved in the < 5 mmHg, < 10 mmHg, and <15 mmHg categories, respectively. A letter grade of "B" requires that over 50%, 75%, and 90% were achieved in the < 5 mmHg, < 10 mmHg, and <15 mmHg categories, respectively. The test device achieved a grade of (A/A) with the validation data from this study.

Blood pressure was measured an average of 9 times for each participant during their single measurement period, and the average of those measurements was recorded. Each measurement period lasted approximately 30-45 minutes

Inclusion Criteria: Pregnant women receiving antenatal care at the UT OB/GYN clinic. Over the age of 18 Exclusion Criteria: Women under the age of 18 Women unable to provide informed consent

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