NONINVASIVE PHYSIOLOGICAL MONITORING OF HIGH-RISK SURGICAL PATIENTS

Objectives: To study the feasibility of multicomponent noninvasive mon itoring, consisting of a new bioimpedance method for estimating cardia c output together with routine pulse oximetry and transcutaneous oxime try, and to compare physiologic data obtained noninvasively with hemod ynamic and oxygen transport data obtained by standard invasive pulmona ry artery thermodilution catheter to evalu ate circulatory function in high-risk surgical patients. Design: Prospective descriptive analysis of the time course of physiologic patterns in surgical patients. Sett ing: University-run county hospital. Patients: Seventy-one consecutive ly monitored, highrisk, critically ill surgical patients in their peri operative period. Outcome Measures: Simultaneous measurements by invas ive and noninvasive methods to describe and compare the temporal physi ologic patterns of survivors and nonsurvivors. Results: The new impeda nce cardiac output estimations closely approximated those of the therm odilution method (r=0.82, P<.001). Episodes of hypotension, tachycardi a, low cardiac index, arterial hemoglobin desaturation, low transcutan eous oximetry, reduced oxygen delivery, and low oxygen consumption occ urred with both groups but were more pronounced in the nonsurvivors th an in the survivors. Noninvasive monitoring provided information simil ar to that of the thermodilution method. Both approaches indicated low flow and poor tissue perfusion (oxygenation) that was worse in the no nsurvivors. Conclusions: The multicomponent noninvasive monitoring pro vides continuous online, real-time displays of physiologic data that a llow immediate recognition of circulatory dysfunction as well as the m eans to titrate therapy to appropriate predetermined therapeutic goals . The noninvasive systems are easy to apply, safe, inexpensive, reason ably accurate, and cost-effective.