Wearable devices measure postoperative cardiac parameters in ICU

Wearable photoplethysmography (PPG)-based devices can accurately measure cardiac-related parameters and may enable noninvasive monitoring in the immediate postoperative and intensive care settings, according to a recent study.

“In this observational study, we have shown that the tested noninvasive, PPG-based devices provide an accurate assessment of systolic (SBP) and diastolic (DBP) blood pressure, mean arterial pressure (MAP), and pulse rate (PR) compared to the invasive, gold-standard measurements obtained using an arterial line (AL) in postcardiac surgery patients,” the researchers said.

Ten patients (mean age 60±15 years), who were immediately admitted to the cardiac surgery intensive care unit (CSICU) after cardiac surgery, were enrolled and given both the wrist-worn and chest-patch configurations of a wireless PPG-based device. BP and PR measurements were compared to those by an invasive AL transducer, which was taken as the gold standard.

Participants were monitored for an average of 549±251 minutes, during which no adverse event related to both device configurations was reported. AL use likewise yielded no complications. [Front Med 2021;8:693926]

Comparing SBP, DBP, and MAP measurements revealed a relatively small bias of <1-mm Hg for both the chest patch and wristwatch monitors as compared with the AL standard. Limits of agreement (LOA) were also narrow for all three pressure measurements, suggesting good agreement between the wearable monitors and AL.

The same was true for PR, for which the wristwatch and chest patch monitors had a small bias of <1 beat/min and a narrow LOA of –3,3 beat/min relative to AL.

Correlation analysis further revealed that AL BP measurements were significantly associated with those from the wristwatch (SBP: r, 0.94; DBP: r, 0.93; MAP: r, 0.96; p<0.001 for all) and chest patch (SBP: r, 0.95; DBP: r, 0.93; MAP: r, 0.95; p<0.001 for all) wearable monitors. Similar findings were obtained for PR (wristwatch: r, 0.99; chest patch: r, 0.99; p<0.001 for both).

Moreover, both wristwatch and chest patch configurations performed comparably, yielding only small biases and narrow LOAs for BP parameters. Measurements were likewise significantly and strongly correlated between both configurations (r, 0.91, 0.87, and 0.92 for SBP, DBP, and MAP, respectively; p<0.001 for all).

“This PPG-based technology enables continuous, noninvasive remote patient monitoring and timely focused care, which may minimize morbidity and mortality without compromising measurement accuracy,” the researchers said.

“Future studies should focus on the advanced monitoring capabilities of these devices in a variety of clinical settings, from immediate hospital-based post-operative and intensive care units to posthospital and ambulatory settings,” they added.