AN EVALUATION OF THE N-CAT, A NEW ARTERIAL TONOMETER

The N-CAT is a newly developed arterial tonometer (TBP) monitor able t o determine systolic, diastolic and mean blood pressures continuously and noninvasively. The aim of this study was to evaluate the accuracy and reliability of the TBP compared with directly measured invasive bl ood pressure (IBP) in 14 patients before and after elective coronary a rtery bypass surgery. Although the TBP was able to track changes in sy stemic pressure, before and after CPB, bias and precision for TBP moni toring did nor meet the standard criteria for equivalency for noninvas ive blood pressure to invasive blood pressure. We were unable to monit or TBP in two patients Approximately 40% of all before and after CPB m ean TBP pressure values differed from mean IBP by more than 10 mmHg. M oreover, there were discrepancies of sufficient magnitude and duration that limits the clinical usefulness of the N-CAT. Potential users sho uld not rely exclusively on TBP values when making clinical decisions. Technological improvement is needed before its clinical use is recomm ended.