Comparing Cardiac Output Measurements Using a Wearable, Wireless, Noninvasive Photoplethysmography-Based Device to Pulse Contour Cardiac Output in the General ICU: A Brief Report

OBJECTIVES: Cardiac output (CO) measurements in the ICU are usually based on invasive techniques, which are technically complex and associated with clinical complications. This study aimed to compare CO measurements obtained from a noninvasive photoplethysmography-based device to a pulse contour cardiac output device in ICU patients. DESIGN: Observational, prospective, comparative clinical trial. SETTING: Single-center general ICU. PATIENTS: Patients admitted to the general ICU monitored using a pulse contour cardiac output device as per the decision of the attending physician. INTERVENTIONS: Parallel monitoring of CO using a photoplethysmography-based chest patch device and pulse contour cardiac output while the medical team was blinded to the values obtained by the noninvasive device. MEASUREMENTS AND MAIN RESULTS: Seven patients (69 measurements) were included in the final analysis. Mean CO were 7.3 ± 2.0 L/m and 7.0 ± 1.5 L/m for thermodilution and photoplethysmography, respectively. Bland-Altman showed that the photoplethysmography has a bias of 0.3 L/m with –1.6 and 2.2 L/m 95% limit of agreement (LOA) and a bias of 2.4% with 95% LOA between –25.7% and 30.5% when calculating the percentage of difference from thermodilution. The values obtained by thermodilution and photoplethysmography were highly correlated (r = 0.906). CONCLUSIONS: The tested chest patch device offers a high accuracy for CO compared to data obtained by the pulse contour cardiac output and the thermodilution method in ICU patients. Such devices could offer advanced monitoring capabilities in a variety of clinical settings, without the complications of invasive devices.