Intraoperative Blood Pressure Monitoring in Obese Patients
Insights
Continuous noninvasive finger cuff blood pressure monitoring shows better agreement with intraarterial measurements than intermittent oscillometry in obese surgical patients. Forearm oscillometry also demonstrated improved accuracy compared to upper arm or lower leg measurements.
Area of Science:
- Anesthesiology
- Cardiovascular Physiology
- Medical Devices
Background:
- Optimal blood pressure monitoring in obese surgical patients is undetermined.
- Arterial catheters pose risks, and oscillometry offers intermittent data.
- Finger cuffs enable continuous, noninvasive monitoring.
Purpose of the Study:
- To compare the agreement of finger cuff and oscillometric blood pressure measurements against intraarterial measurements.
- To evaluate continuous noninvasive monitoring methods in obese surgical patients.
Main Methods:
- Prospective study involving 90 obese patients undergoing bariatric surgery.
- Comparison of intraarterial (reference), finger cuff, and oscillometric (upper arm, forearm, lower leg) methods.
- Analysis using Bland-Altman, four-quadrant plots, concordance, and error grid analyses.
Main Results:
- Finger cuff agreement with intraarterial measurements was superior for mean arterial and diastolic pressures.
- Concordance for changes was 88% (MAP), 85% (SBP), and 81% (DBP) for finger cuffs.
- Forearm oscillometry showed better agreement than upper arm or lower leg sites.
Conclusions:
- Finger cuff monitoring offers better agreement than oscillometry for mean arterial and diastolic pressures in this population.
- Continuous noninvasive monitoring is a viable option for obese surgical patients.
- Forearm oscillometry provides more accurate readings than other oscillometric sites.
Background:
The optimal method for blood pressure monitoring in obese surgical patients remains unknown. Arterial catheters can cause potential complications, and noninvasive oscillometry provides only intermittent values. Finger cuff methods allow continuous noninvasive monitoring. The authors tested the hypothesis that the agreement between finger cuff and intraarterial measurements is better than the agreement between oscillometric and intraarterial measurements.
Methods:
This prospective study compared intraarterial (reference method), finger cuff, and oscillometric (upper arm, forearm, and lower leg) blood pressure measurements in 90 obese patients having bariatric surgery using Bland-Altman analysis, four-quadrant plot and concordance analysis (to assess the ability of monitoring methods to follow blood pressure changes), and error grid analysis (to describe the clinical relevance of measurement differences).
Results:
The difference (mean ± SD) between finger cuff and intraarterial measurements was -1 mmHg (± 11 mmHg) for mean arterial pressure, -7 mmHg (± 14 mmHg) for systolic blood pressure, and 0 mmHg (± 11 mmHg) for diastolic blood pressure. Concordance between changes in finger cuff and intraarterial measurements was 88% (mean arterial pressure), 85% (systolic blood pressure), and 81% (diastolic blood pressure). In error grid analysis comparing finger cuff and intraarterial measurements, the proportions of measurements in risk zones A to E were 77.1%, 21.6%, 0.9%, 0.4%, and 0.0% for mean arterial pressure, respectively, and 89.5%, 9.8%, 0.2%, 0.4%, and 0.2%, respectively, for systolic blood pressure. For mean arterial pressure and diastolic blood pressure, absolute agreement and trending agreement between finger cuff and intraarterial measurements were better than between oscillometric (at each of the three measurement sites) and intraarterial measurements. Forearm performed better than upper arm and lower leg monitoring with regard to absolute agreement and trending agreement with intraarterial monitoring.
Conclusions:
The agreement between finger cuff and intraarterial measurements was better than the agreement between oscillometric and intraarterial measurements for mean arterial pressure and diastolic blood pressure in obese patients during surgery. Forearm oscillometry exhibits better measurement performance than upper arm or lower leg oscillometry.
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