ASSESSMENT OF THE ARTERIAL TONOMETER (N-CAT) FOR THE CONTINUOUS BLOOD-PRESSURE MEASUREMENT IN RAPID ATRIAL-FIBRILLATION

The N-CAT is a newly developed arterial tonometer (TBP) able to determ ine systolic, diastolic and mean arterial blood pressures continuously and noninvasively. The aim of this study was to evaluate the accuracy and reliability of TBP relative to directly measured invasive blood p ressure (IBP) in ten haemodynamically stable postoperative cardiac pat ients who were in rapid atrial fibrillation (HR greater-than-or-equal- to 100 bpm). There were differences between TBP and IBP for systolic ( -1.7 mmHg) and diastolic (+0.9 mmHg) values but not for the mean arter ial blood pressures. The N-CAT was able to follow blood pressure chang es closely and demonstrated an average systolic, diastolic and mean bi as (+/- SD) of -1.71 +/- 4.6, 0.99 +/- 4.6 and 0.33 +/- 4.2 mmHg, resp ectively. Although these biases are within the required standards for equivalency for noninvasive blood pressure to invasively determined bl ood pressure, approximately 20% of the readings were > +/- 10 mmHg whi le only 5% were > +/- 20 mmHg. Moreover, there were occasional discrep ancies of sufficient magnitude and duration which may limit the clinic al usefulness of the N-CAT in patients in whom continuous and accurate blood pressure measurement is required.