Noninvasive Hemodynamic Monitoring of Critical Patients in the Emergency Department

Objective : To evaluate the feasibility of multicomponent noninvasive hemodynamic monitoring in critical emergency patients and to compare this technique with simultaneous invasive monitoring by the pulmonary artery thermodilution catheter.
Methods : A prospective observational study was done comparing invasive monitoring and noninvasive monitoring in 60 critically ill or injured patients who required hemodynamic monitoring shortly after entering the ED of a university-affiliated county hospital. Cardiac output (CO) values measured by the standard thennodilution pulmonary artery catheter technique were compared with simultaneously obtained measurements using a noninvasive bioimpedance method. Concurrent measurements were made of pulse oximetry to screen pulmonary function and transcutaneous oximetry to assess tissue perfusion.
Results : The impedance CO values closely approximated those for the thermodilution method; r 0.81, p < 0.001. Significant circulatory abnormalities, including hypotension, reduced cardiac index, arterial hemoglobin desaturation, tissue hypoxia, reduced O₂ delivery, and consumption, were found in 54 of the 60 (90%) patients. The cardiac index decreased in 44% of the patients, the transcutaneous O₂ decreased in 39%. and the O₂ saturation by pulse oximetry fell in 22% during the observation period in the ED (commonly lasting 2–8 hours).
Conclusions: Noninvasive monitoring can provide hemodynamic and perfusion information previously available only by invasive thermodilution catheters. Such noninvasive monitoring can display continuous on-line real-time data, allowing immediate recognition of circulatory abnormalities and providing a means to titrate therapy to appropriate therapeutic goals.