Clinical validation of a continuous non-invasive haemodynamic monitor (CNAP&trade; 500) during general anaesthesia.
BACKGROUND
We conducted a prospective study to test the validity of a new continuous non-invasive blood pressure (NIBP) monitor (CNAP) (CNAP™ Monitor 500).


METHODS
One hundred patients undergoing elective surgery under general anaesthesia were included in the study after informed written consent. The CNAP finger cuffs were placed on the fingers of one arm, an arterial catheter was inserted into the same arm and data were recorded simultaneously. Agreement between invasive arterial pressure (IAP) and blood pressure obtained by CNAP was compared using the Bland-Altman method for repeated measurements. The data from the first 50 patients (software V3.0) were used to improve the software of the CNAP (software V3.5), which was then evaluated in another 50 patients. We defined a clinically acceptable agreement according to the standards of the American Association for the Advancement of Medical Instrumentation for NIBP measurements [limits of agreement (LOA) ± 15 mm Hg].


RESULTS
We analysed 524 878 paired measurements in 100 patients. The mean bias of the mean arterial pressure in the first 50 patients was -2.9 mm Hg (sd 10.6 mm Hg, LOA -23.7 to 17.9 mm Hg), and in the consecutive 50 patients (using software V3.5) the bias was -3.1 mm Hg (sd 9.5 mm Hg, LOA -21.6 to 15.4 mm Hg).


CONCLUSIONS
The new CNAP monitor showed an agreement with the IAP that is promising but did not match our predefined criteria.
Department of Anaesthesia, General Intensive Care and Pain Control, Medical University of Vienna, Waehringer Guertel 18-20, Vienna A-1090, Austria. reinhard.hahn@meduniwien.ac.at
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Neuner
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Kettner
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D001794:Blood Pressure; D001795:Blood Pressure Determination; D015924:Blood Pressure Monitors / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D011446:Prospective Studies; D015203:Reproducibility of Results