Clinical comparison of automated auscultatory and oscillometric and catheter-transducer measurements of arterial pressure.

Arterial pressure measurements recorded from a radial artery catheter-transducer (RAC) system were compared with similar data obtained from an automated sphygmomanometer that uses both oscillometric (OSC) and auscultatory measurement techniques. Data were obtained from 50 patients during and immediately after surgery. The fundamental frequency of the RAC system was 23.7 +/- 6.7 Hz (mean +/- SD; range, 13 to 40 Hz), and the damping coefficient was 0.26 +/- 0.06 (mean +/- SD; range, 0.15 to 0.34). Linear regression analysis of RAC against OSC values (n = 385) revealed the following correlations: (1) systolic pressure: OSC = 0.92(RAC) + 3.5, r = 0.91; (2) diastolic pressure: OSC = 0.92(RAC) + 1.3, r = 0.76; and (3) mean pressure: OSC = 0.96(RAC) + 0.68, r = 0.84. There were significant differences between each pair of pressure values; mean percent differences (RAC pressure minus OSC pressure) were 4.5 +/- 0.3%, 5.5 +/- 0.7%, and - 2.7 +/- 0.5% for systolic, diastolic, and mean values, respectively. Manual and automated auscultatory measurements closely agreed, and both correlated well with OSC values for systolic and diastolic pressure. However, both manual and automated auscultatory, as well as OSC measurements, underestimated RAC systolic and overestimated RAC diastolic pressure.