Authors: Weiss E et al., Br J Anaesth 2014 Jul 113:52
A new finger-cuff device might be useful as an early warning system for hemodynamic variability, but it is not a replacement for invasive monitoring.
The Nexfin is a noninvasive finger-cuff device that uses photoplethysmographic technology to continuously measure arterial pressure. To compare Nexfin measurements to intra-arterial pressure (IAP) measured by ipsilateral radial artery catheterization, researchers recorded blood pressures (BPs) with both methods every 5 seconds during induction of elective anesthesia in 31 adults.
A total of 3479 paired measurements were analyzed. The Nexfin reliably and quickly detected 100% of arterial pressure changes. Mean differences between the Nexfin and IAP measurements at BP nadir were -1 mm Hg for systolic BP and -7 mm Hg for diastolic BP, but there was wide variation in the actual measurements (e.g., -28 to +25 mm Hg for systolic BP). Corresponding differences at BP peak averaged -10 mm Hg and -13 mm Hg, with a range of -60 to +40 mm Hg for systolic BP.
In prior studies, noninvasive arterial pressure monitoring has compared favorably to traditional cuff pressure but not to invasive monitoring (NEJM JW Emerg Med Mar 11 2014, NEJM JW Emerg Med May 13 2014). Based on those studies and the current study, finger photoplethysmography is relegated to a supporting role as a reasonable alternative to traditional automated blood pressure cuff monitoring, but it is not a substitute for measurement by intra-arterial catheter.