Noninvasive continuous versus intermittent arterial pressure monitoring: evaluation of the vascular unloading technique (CNAP device) in the emergency department

Abstract

BackgroundMonitoring cardiovascular function in acutely ill patients in the emergency department (ED) is of paramount importance. Arterial pressure (AP) is usually monitored using intermittent oscillometric measurements with an upper arm cuff. The vascular unloading technique (VUT) allows continuous noninvasive AP monitoring. In this study, we compare continuous AP measurements obtained by VUT with intermittent oscillometric AP measurements in ED patients. In addition, we aimed to investigate whether continuous noninvasive AP monitoring allows detection of relevant hypotensive episodes that might be missed with intermittent AP monitoring.MethodsIn a German university hospital, 130 ED patients who required AP monitoring were analyzed in this prospective method comparison study. Continuous AP monitoring was performed using VUT (CNAP technology; CNSystems Medizintechnik AG, Graz, Austria) over a 2-hour period. The oscillometric AP values were recorded simultaneously every 15 minutes for the comparison of both methods. For statistical evaluation, Bland-Altman plots accounting for repeated AP measurements per individual were used.ResultsThe mean difference (±standard deviation) between AP measurements obtained by VUT and oscillometric AP measurements was -5 mmHg (±22 mmHg) for systolic AP (SAP), -2 mmHg (±15 mmHg) for diastolic AP (DAP), and -6 mmHg (±16 mmHg) for mean AP (MAP), respectively. In the interval between two oscillometric measurements, the VUT device detected hypotensive episodes (≥4 minutes) defined as either SAP <90 mmHg or MAP <65 mmHg in 30 patients and 16 patients, respectively. In 11 (SAP <90 mmHg) and 6 (MAP <65 mmHg) of these patients, hypotension was also detected by the subsequent intermittent oscillometric AP measurement.ConclusionsVUT using the CNAP system for noninvasive continuous AP measurement shows reasonable agreement with intermittent oscillometric measurements in acutely ill ED patients. Continuous AP monitoring allows immediate recognition of clinically relevant hypotensive episodes, which are missed or only belatedly recognized with intermittent AP measurement.

Continuous noninvasive cardiac output determination using the CNAP system: evaluation of a cardiac output algorithm for the analysis of volume clamp method-derived pulse contour

“…Studies have shown that the technology provides arterial pressure values with reasonable agreement in comparison with invasive arterial pressure measurements in anesthetized patients during surgical procedures [5][6][7], intensive care unit (ICU) patients [8,9], and emergency department patients [10].…”

Measurement of blood pressure

“…blood transfusions, vasopressor infusions) depending on the BP monitoring method used. Besides these inaccuracies concerning BP measurements, the treating physician should be aware that clinically relevant hypotensive episodes might be missed or detected late by oscillometric versus continuous beat-to-beat BP [45]. The lack of adequate oscillometric BP validation studies and their demonstrated shortcomings should lead to reconsidering the confidence in oscillometric BP.…”

“…The CNAP system improved the detection of fast BP changes in patients receiving sedating agents during interventional endoscopy [59]. Further, it has high potential to improve patient safety during caesarian section [60] and in acutely ill patients admitted to the emergency room [45] -clinical scenarios in which arterial cannulation is not clearly indicated or challenging.…”

Tetrahydrobiopterin ameliorates the exaggerated exercise pressor response in patients with chronic kidney disease: a randomized controlled trial

“…Continuous ECG was recorded simultaneously with the neurogram using a bioamp system. Beat-to-beat arterial BP was measured noninvasively using finger cuffs that detect digital blood flow and translate blood flow oscillations into continuous pulsepressure waveforms and beat-to-beat values of BP (CNAP, CNSystems) (20,46,47,52,55). Absolute values of BP were internally calibrated using a concomitant upper arm BP reading and were calibrated at the start and every 15 min throughout the study.…”