Validation of the Nexfin® non-invasive continuous blood pressure monitoring validated against Riva-Rocci/Korotkoff in a bariatric patient population

Study objective The present study aimed to validate the Nexfin® monitor and to assess the accuracy compared to classical sphygmomanometry (Riva-Rocci/Korotkoff (RRK)) blood pressure (BP) measurements in patients with obesity scheduled for bariatric surgery. Design Validation study. Setting Outpatient clinic for bariatric surgery. Patients 33 patients scheduled for bariatric surgery. Measurements The validation process was done according to the protocols developed by the European Society of Hypertension from 2010. The Nexfin® monitor (Edwards Lifesciences/BMEYE B.V., Amsterdam, The Netherlands) calculates beat-to-beat blood pressure from finger pulse wave analysis. Measurements of systolic and diastolic BP were obtained using classical sphygmomanometry and the Nexfin® alternatingly. Main results In total 99 pairs of BP measurements were used. The device failed pass phase 1 as 65 systolic readings fell within 5 mm Hg (73 required). And 61, 76 and 90 diastolic readings fell within 5, 10 and 15 mm Hg respectively. Finally, it failed to pass phase 2 as 23 patients for systolic and 25 for diastolic had at least 2/3 of their comparisons falling within 5 mm Hg (24 required) but 10 subjects for systolic and 8 for diastolic had all three comparisons more than 5 mm Hg different from the RRK readings (zero allowed). Mean differences were 7.8 ± 6.9 mm Hg for SBP and 8.0 ± 7.2 mm Hg for DBP. Conclusion Using the revised protocol, the Nexfin® device was not able to pass validation. However using the original protocol, the Nexfin® device passed phase 1 and 2.1 of the validation process and failed to pass phase 2.2.