Abstract 16382: Inaccuracy of Non-Invasive Brachial Cuff-Measured Blood Pressure During Surgery

Abstract

Introduction: Blood pressure (BP) is an essential vital sign to be monitored during surgery. BP is measured only by Non-Invasive brachial Cuff-measured Blood Pressure (NICBP) devices in 90% of surgeries in US. However, previous studies demonstrated possible inaccuracy of NICBP. The inaccuracy of BP during surgery is a significant public concern because it can result in missing therapeutic potentials and consequently increasing cardiovascular risks during and after surgery. However, there is no large study to evaluate the accuracy of NICBP measured during surgery. Method: It has been known that invasive intra-arterial blood pressure (IABP) measured by an arterial line catheter is an optimal reference for validation of NICBP accuracy given its highest level of accuracy. Our study collected 2,814,154 pairs of BP measurements between NICBP and IABP which were measured at the same time during surgery from 38,706 patients who received surgeries at University of California, Los Angeles from 2016 through 2023. Result: We evaluated the accuracy of NICBP compared to IABP using Confusion matrix analysis (Fig 1). We defined predicted BP classification when BP is classified by NICBP. We also defined actual BP classification when BP is classified by IABP. We categorized BP according to Mean Arterial Pressure (MAP; mmHg) into 5 groups; MAP<65, 65≤MAP<75, 75≤MAP<95, 95≤MAP<105, and 105≤MAP. True Positive rates of each classification ranged from 36.7% to 66.7% (Fig 1). It was surprising that 49.9% in actual MAP (aMAP)<65, 56.9% in 65≤aMAP<75, 33.9% in 75≤aMAP<95, 63.4% in 95≤aMAP<105, and 50.6% in 105≤ aMAP was misclassified into the incorrect BP classifications by NICBP. Conclusion: Our study demonstrated noticeable inaccuracy of BP by NICBP compared to IABP during surgery. Given high reliability solely on NICBP in measuring BP during the majority of surgery cases, the inaccuracy of NICBP may cause significant public health concerns due to unoptimized BP management during surgery.