The performance of estimating Systolic Blood Pressure (SBP) in anesthetized patients via Pulse Arrival Time (PAT) techniques was studied with respect to the minimum required time in between two recalibration procedures. Materials: a clinical trial [NCT026515581 involving 14 patients was conducted measuring PAT from an ECG and an arterial line inserted into the radial artery. Methods: comparison of BP estimates from PAT measurements against invasive BP values was performed in terms of mean error and standard deviation of the error (AAMI/ANSI/ISO 81060-2), cumulative percentage of readings falling within 5, 10 and 15 mmHg (BHS criteria), and MAD Mean Absolute Difference (IEEE Std 1708). Two calibration strategies were explored, involving time between recalibration periods ranging from 10 seconds to 8 minutes. Results: assuming an affine calibration function between PAT and SBP, different slope (Mean Slope:-1.45, CI:-1.64 to -1.27 mmHg/ms) and offset values (Mean Offset: 575, CI: 517 to 633 mmHg) were found in between patients. In addition, given a patient, affine calibration functions at different anesthesia phases also showed to be variable. When assessing agreement in terms of existing international standards it was found that PAT based SBP estimates complied with requirements when time between two calibrations was smaller than 60 seconds. Conclusions: the use of anesthetic agents compromises the implementation of PAT-based techniques to estimate SBP.
in Embec and Nbc 2017. vol. 65 (Issue), H. Eskola, O. Vaisanen, J. Viik, and J. Hyttinen, Eds., ed Singapore: Springer-Verlag Singapore Pte Ltd, 2018, pp. 864-867.