Noninvasive central aortic pressure estimation via generalized transfer function yields errors equivalent to oscillometric monitors, with SBP-C error highly correlated to SBP-O error (r=0.88, P<0.01).
Observational (n=40)
Does noninvasive estimation using a generalized transfer function accurately reflect invasively measured central aortic blood pressures in patients undergoing cardiac catheterization?
Noninvasive transfer function techniques produce estimates of central aortic blood pressures with errors equivalent to those of the oscillometric blood pressure monitor used for calibration.
Effect estimate: r = 0.88
p-value: p=<0.01
BACKGROUND: The accuracy of the central aortic systolic (SBP-C) and pulse (PP-C) blood pressures estimated noninvasively by a generalized transfer function technique has been questioned. The purpose of the present study was to quantify precisely the impact of the input errors (differences between the oscillometric (SBP-O, DBP-O, PP-O) and invasive (SBP-B, DBP-B, PP-B) brachial systolic, diastolic, and pulse blood pressures) on the output errors (differences between the estimated and invasively measured SBP-C and PP-C). METHODS: Invasive high-fidelity right brachial and central aortic pressure waveforms, and SBP-O, DBP-O, and PP-O (=SBP-O - DBP-O) were obtained simultaneously in 40 patients during cardiac catheterization. A generalized transfer function was applied on the individual brachial pressure waveform to derive predicted SBP-C and PP-C. RESULTS: Observed input errors were -2.3 ± 5.8 mm Hg from SBP-O, 8.1 ± 5.3 mm Hg from DBP-O, and -10.4 ± 7.1 mm Hg from PP-O, respectively. The output errors were -2.2 ± 6.4 mm Hg and -10.3 ± 8.0 mm Hg for SBP-C and PP-C, respectively, when the brachial pressure waveforms were recalibrated using SBP-O and DBP-O. The outputs were determined by the inputs according to the Equation (1): SBP-C error = 0.97 × SBP-O error + 0.03 (r = 0.88, P < 0.01); and the Equation (2): PP-C error = 0.96 × PP-O error - 0.30 (r = 0.86, P < 0.01). CONCLUSIONS: Noninvasive application of the generalized transfer function techniques produces estimates of SBP-C and PP-C with errors equivalent to those of the oscillometric blood pressure monitor in the estimation of SBP-B and PP-B. The output errors can be predicted from input errors of SBP-O and DBP-O.
Shih et al. (Thu,) conducted a observational in Patients undergoing cardiac catheterization (n=40). Generalized transfer function technique vs. Invasive central aortic pressure measurement was evaluated on Output errors (differences between estimated and invasively measured SBP-C and PP-C) (r = 0.88, p=<0.01). Noninvasive central aortic pressure estimation via generalized transfer function yields errors equivalent to oscillometric monitors, with SBP-C error highly correlated to SBP-O error (r=0.88, P<0.01).
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