Effect of Elevated Ambient Temperature on Simulator-Derived Oscillometric Blood Pressure Measurement.

BACKGROUND: Oscillometric blood pressure (BP) devices are typically labeled for use up to 40 °C. Many geographic regions have ambient temperatures exceeding 40 °C. We assessed the effect of increased ambient temperature (40-55 °C) on simulator-derived oscillometric BP measurement. METHODS: Three Omron BP769CAN devices, 3 A&D Medical UA-651BLE devices, and accompanying cuffs were used. A custom heat chamber heated each device to the specified temperature. A noninvasive BP simulator was used to take 3 measurements with each device at differing temperatures (22, 40, 45, 50, and 55 °C) and BP thresholds: 80/50, 100/60, 120/80, 140/90, 160/110, and 180/130 mm Hg. Using each device as its own control (22 °C), we determined the relative differences in mean BP for each device at each temperature and BP setting, assessed graphical trends with increasing temperature, and examined variability. RESULTS: Graphical trends of mean simulator-subtracted BP differences from room temperature showed no discernable pattern, with differences clustered around zero. Overall mean difference in BP (combined elevated temperatures minus room temperature) was -0.8 ± 2.1 (systolic ± SD)/1.2 ± 3.5 (diastolic ± SD) mm Hg for the A&D device and 0.2 ± 0.4 (systolic ± SD)/-0.1 ± 0.1 (diastolic ± SD) mm Hg for the Omron. All individual elevated temperature differences (elevated temperature minus room temperature) except A&D diastolic BP at 50 °C were within 5 mm Hg. CONCLUSIONS: In this simulator-based study assessing within-device differences, higher ambient temperatures resulted in oscillometric BP measurements that were comparable to those performed at room temperature.

Patient perceptions of ambulatory blood pressure monitoring testing, tolerability, accessibility, and expense.

Use of 24-hour ambulatory blood pressure monitoring is strongly endorsed by contemporary hypertension guidelines. The objective of this study was to assess patient perceptions of ambulatory blood pressure testing, tolerability, accessibility, and expense. A convenience sample of 50, consenting patients undergoing ambulatory blood pressure monitoring at the University of Alberta Hypertension Clinic in Edmonton, Canada was studied. A 16-item structured questionnaire was administered in person or electronically. Questions regarding the tolerability of ambulatory monitoring were evaluated using a 5-point Likert scale and wait times, expenditures, and willingness to pay were evaluated by direct questioning. Mean age was 53.1 ± 15.4 years, 32 (64%) were female, and 23 (46%) were employed. Mean 24-hour ambulatory BP was 134 ± 12/79 ± 8 mmHg. Ambulatory monitoring caused discomfort in 40 (80%) patients and disturbed sleep in 39 (78%). Forty-one (82%) patients perceived that the home (vs pharmacy, primary care clinic, and speciality care clinic) would be the easiest venue to access future testing. On average, patients waited 27.3 ± 23.7 days for testing; they felt that a wait time of 21.3 ± 12.3 days was appropriate. Mean time taken off work was 8.6 ± 10.8 hours. Twelve (24%) patients indicated that they would be willing to pay out-of-pocket to undergo testing sooner, at a mean expenditure of $120 ± 69. Nineteen (62%) patients were willing to buy a monitor and felt that a mean purchase cost of $125 ± 89 was appropriate. These findings extend current knowledge of patient perceptions of ambulatory monitoring and may help to refine and optimize future delivery of this essential test.