Outcome prediction of emergency patients by noninvasive hemodynamic monitoring

We used noninvasive hemodynamic monitoring in the initial resuscitation beginning in the emergency department (ED) for the following reasons: (1) to describe early survivor and nonsurvivor patterns of emergency patients in terms of cardiac, pulmonary, and tissue perfusion deficiencies; (2) to measure quantitatively the net cumulative amount of deficit or excess of the monitored functions that correlate with survival or death; and (3) to explore the use of discriminant analysis to predict outcome and evaluate the biological significance of monitored deficits.

This is a descriptive study of the feasibility of noninvasive monitoring of patients with acute emergency conditions in the ED to evaluate and quantify hemodynamic deficits as early as possible. The noninvasive monitoring systems consisted of a bioimpedance method for estimating cardiac output together with pulse oximetry to reflect pulmonary function, transcutaneous oxygen tension to reflect tissue perfusion, and BP to reflect the overall circulatory status. These continuously monitored noninvasive measurements were used to prospectively evaluate circulatory patterns in 151 consecutively monitored severely injured patients beginning with admission to the ED in a university-run county hospital. The net cumulative deficit or excess of each monitored parameter was calculated as the cumulative difference from the normal value vs the time-integrated monitored curve for each patient. The deficits of cardiac, pulmonary, and tissue perfusion functions were analyzed in relation to outcome by discriminant analysis and were cross-validated.

The mean (+/- SEM) net cumulative excesses (+) or deficits (-) from normal in surviving vs nonsurviving patients, respectively, were as follows: cardiac index (CI), +81 +/- 52 vs -232 +/- 138 L/m(2) (p = 0.037); arterial hemoglobin saturation, -1 +/- 0.3 vs -8 +/- 2.6%/h (p = 0.006); and tissue perfusion, +313 +/- 88 vs -793 +/- 175, mm Hg/h (p = 0.001). The cumulative mean arterial BP deficit for survivors was -10 +/- 13 mm Hg/h, and for nonsurvivors it was -57 +/- 24 mm Hg/h (p = 0.078).

Noninvasive monitoring systems provided continuously monitored on-line displays of data in the early postadmission period from the ED to the operating room and to the ICU for early recognition of circulatory dysfunction in short-term emergency conditions. Survival was predicted by discriminant analysis models based on the quantitative assessment of the net cumulative deficits of CI, arterial hypoxemia, and tissue perfusion, which were significantly greater in the nonsurvivors.