A systemic proinflammatory response has been implicated in the pathogenesis of organ dysfunction. The effects of surgery, surgical stress, anesthesia, and subsequent intensive care unit (ICU) resuscitation may affect the components of the systemic inflammatory response syndrome (SIRS) score (temperature, heart rate, respiratory rate, and white blood cell count). Any SIRS scores calculated within 24 hours after surgery or at the onset of nonoperative resuscitation may overestimate the proinflammatory response itself, making quantitation of SIRS at that time potentially too sensitive. We hypothesized that SIRS attributable to ICU resuscitation can be quantitated, and that SIRS after the first day of therapy in the ICU correlates with several outcomes.
Prospective analysis of 2300 surgical ICU admissions during a 49-month period. Acute Physiology and Chronic Health Evaluation III (APACHE III) scores were recorded after 24 hours. Daily and cumulative multiple organ dysfunction scores (0-4 points for each of 6 organs, 24 points total) and SIRS scores (1 point for each parameter, 4 points total) were recorded. Defined end points were hospital mortality, days in the ICU, and organ dysfunction.
On day 1, 49.4% of patients had SIRS (score ≥2), whereas 34.5% of patients who remained in the ICU had SIRS (score ≥2) on day 2 (P<.001). The SIRS score decreased by a mean of 0.8 points from day 1 to day 2, regardless of the type of admission. A SIRS score that decreased on day 2, in comparison with the score on day 1, resulted in less mortality than a unchanged or higher score on day 2 (11% vs 18% vs 22%, P<.001). Systemic inflammatory response scores were higher for nonsurvivors than survivors on each of the first 7 days in the ICU. The day 2 SIRS score correlated well with the admission APACHE III score (P<.001) and all defined end points (all P<.001). The day 2 SIRS score also correlated with the day 2 multiple organ dysfunction score (P<.001). By multiple logistic regression, APACHE III (P<.001), day 2 SIRS score (P<.01) (but not day 1 SIRS score, P=.99), and day 2 multiple organ dysfunction score (P<.001) (but not day 1 multiple organ dysfunction score, P=.81) predicted mortality.
Systemic inflammatory response syndrome attributable to surgery or surgical stress can be quantitated. Twenty-four hours of ICU resuscitation results in a decline in the SIRS score. The magnitude of the proinflammatory response on the second ICU day may be a useful predictor of outcome in critical surgical illness.