Comparison of the Finapres blood pressure monitor with intra-arterial manometry during induction of anaesthesia.

The Finapres (Ohmeda, Madison, U.S.A.) is a non-invasive device which continuously measures the arterial blood pressure in a finger and produces a real-time display of the arterial pressure wave. It consists of a finger cuff with an infra-red transmission plethysmograph, a servo control box and a monitor unit. The device was compared with intra-arterial pressure monitoring in twenty patients during induction of anaesthesia for elective neurosurgical procedures. The differences between the two methods were considerable, ranging from -40 mmHg to +26 mmHg for mean pressure. While the Finapres has potential as a non-invasive continuous blood pressure monitor, the current model Finapres, as supplied, displays too great a variability for it to be used as an alternative to intra-arterial pressure monitoring.