Comparison of the non-invasive Nexfin® monitor with conventional methods for
the measurement of arterial blood pressure in moderate risk orthopaedic
surgery patients
Objective Continuous invasive arterial blood pressure (IBP) monitoring remains
the gold standard for BP measurement, but traditional oscillometric non-
invasive intermittent pressure (NIBP) measurement is used in most low-to-
moderate risk procedures. This study compared non-invasive continuous arterial
BP measurement using a Nexfin® monitor with NIBP and IBP monitors. Methods
This was a single-centre, prospective, pilot study in patients scheduled for
elective orthopaedic surgery. Systolic BP, diastolic BP and mean arterial
blood pressure (MAP) were measured by Nexfin®, IBP and NIBP at five
intraoperative time-points. Pearson correlation coefficients, Bland–Altman
plots and trending ability of Nexfin® measurements were used as criteria for
success in the investigation of measurement reliability. Results A total of 20
patients were enrolled in the study. For MAP, there was a sufficient
correlation between IBP/Nexfin® (Pearson = 0.75), which was better than the
correlation between IBP/NIBP (Pearson = 0.70). Bland–Altman analysis of the
data showed that compared with IBP, there was a higher percentage error for
MAPNIBP (30%) compared with MAPNexfin® (27%). Nexfin® and NIBP underestimated
systolic BP; NIBP also underestimated diastolic BP and MAP. Trending ability
for MAPNexfin® and MAPNIBP were comparable to IBP. Conclusion Non-invasive BP
measurement with Nexfin® was comparable with IBP and tended to be more precise
than NIBP