Abstract P192: Is Auscultation Adequate To Estimate Blood Pressure Responses Related To Body Position Changes?
Double-blinded auscultation is the current reference to validate new devices in the sitting position. There are few data to tell whether it should be used for device validation in other body positions, as the Korotkoff sounds can be affected by changes in vascular tone. In this study, we recorded the BP response to orthostatic posture change (standing to supine) in 75 subjects, aged between 21 and 65 years old. Systolic (SBP) and diastolic (DBP) were measured on the left upper arm by auscultation by two independent blinded observers before and 150s after posture change. In case the observers did not agree, i.e. readings differed more than 4 mmHg, the measurement was repeated. Beat-to-beat BP values were measured on the ipsilateral middle finger with Nexfin (BMEYE, The Netherlands). Because Nexfin measurements were not available during upper-arm cuff inflation, the mean of the values in a 30s window prior to auscultation onset was used for the analysis. The distribution of the BP responses to posture change was characterized in terms of median, 10 th and 90 th percentiles (see Table). The response was considered consistent if these percentiles were on the same side of zero. Neither auscultation nor Nexfin detected any consistent posture-related changes in SBP when going from standing to supine. Nexfin detected a consistent decrease in DBP. Auscultation detected no consistent posture-related change. Compared to volume-clamp, auscultation was not able to detect any consistent changes in DBP during orthostatic challenge. Our study suggests that the use of Korotkoff sounds to estimate BP in body positions other than sitting may not be appropriate.