Continuous non-invasive arterial pressure measurement: Evaluation of CNAP™ device during vascular surgery

Objective. - Standard non-invasive blood pressure (BP) monitoring is an intermittent, discontinuous procedure. Beat-to-beat BP monitoring requires invasive measurement via an arterial catheter and may be associated with serious complications. The Infinity (R) CNAP (TM) SmartPod (R) (Drager Medical AG & Co. KG, Lubeck, Germany) has recently been proposed for non-invasive continuous beat-to-beat BP measurements. The present study was designed to compare BP obtained with the CNAP (TM) and with an invasive method in the operating room. Study design. - Prospective study. Patients and methods. - Twenty-five patients undergoing major vascular surgery were included. Systolic, mean and diastolic BP were monitored invasively (SAP, MAP and DAP respectively) and not invasively using the CNAP (TM) (CNAP-S, CNAP-M and CNAP-D respectively). Measurements were performed intraoperatively every minute during 1 hour. Results. - One thousand and five hundred pairs of simultaneous CNAP (TM) and invasive BP measurements were obtained and 148 were eliminated. The range of BP measurements was 63-205 mmHg for SAP and 57-187 mmHg for CNAP-S, 38-143 mmHg for MAP and 43-142 mmHg for CNAP-M, 29-126 mmHg for DAP and 33-121 mmHg for CNAP-D. Bias and 95% limit of agreement between CNAP (TM) and invasive BP measurements were respectively 7.2 and -17.7 to 32.2 mmHg for SAP, -1.8 and -22.0 to 18.3 mmHg for MAP, and -7.5 and -27.3 to 12.4 mmHg for DAP. The percentage of CNAP (TM) measurements with a bias < 10% with the arterial line was 69%, 86% and 91% for systolic, diastolic and mean pressures, respectively. Conclusion. - Despite low accuracy for SAP and DAP measurements, CNAP (TM) system seems more accurate for MAP measurement in patients undergoing vascular surgery. (C) 2010 Elsevier Masson SAS. All rights reserved.