Clinical agreement of a novel algorithm to estimate radial artery blood pressure from the non-invasive finger blood pressure.

Study Objective: A new algorithm was developed that transforms the non-invasive finger blood pressure (BP) into a radial artery BP (B̂P), whereas the original algorithm estimated brachial BP (B̂P). In this study we determined whether this new algorithm shows better agreement with invasive radial BP than the original one and whether in the operating room this algorithm can be used safely.

Design, Setting And Patients: This observational study was conducted on thirty-three non-cardiac surgery patients.

Intervention And Measurements: Invasive radial and non-invasive finger BP were measured, of the latter B̂P and B̂P were transformed. Agreement of systolic, mean, and diastolic arterial BP (SAP, MAP, and DAP, respectively) was assessed traditionally with Bland-Altman and trend analysis and clinically safety was quantified with error grid analyses. A bias (precision) of 5 (8) mmHg or less was considered adequate.

Main Results: Thirty-three patients were included with an average of 676 (314) 20 s segments. For both comparisons, bias (precision) of MAP was within specified criteria, whereas for SAP, precision was higher than 8 mmHg. B̂P showed a better agreement than B̂P with BP for DAP values (bias (precision): 0.7 (6.0) and - 6.4 (4.3) mmHg, respectively). B̂P and B̂P both showed good concordance in following changes in BP (for all parameters overall degree was <7°). There were slightly more measurement pairs of MAP within the no-risk zone for B̂P than for B̂P (96 vs 77%, respectively).

Conclusions: In this cohort of non-cardiac surgery patients, we found good agreement between BP and B̂P. Compared to B̂P, B̂P shows better agreement although clinical implications are small. This trial was registered with ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT03795831).