Persistent Occult Hypoperfusion is Associated with a Significant Increase in Infection Rate and Mortality in Major Trauma Patients

Objective: To investigate the hypothesis that occult hypoperfusion (OH) is associated with infectious episodes in major trauma patients.

Methods: Data were collected prospectively on all adult trauma patients admitted to the Surgical/Trauma Intensive Care Unit from November of 1996 to December of 1998. Treatment was managed by a single physician according to a defined resuscitation protocol directed at correcting OH (lactic acid [LA] > 2.4 mmol/L).

Results: Of a total of 381 consecutive patients, 118 never developed OH and 263 patients exhibited OH. Seventeen patients were excluded because their LA never corrected, and they all subsequently died. One hundred seventy-six infectious episodes occurred in 97 of the 364 patients remaining. The infection rate in patients with no elevation of LA was 13.6% (n = 118) compared with 12.7% (n = 110) in patients whose LA corrected by 12 hours, 40.5% (n = 79; p < 0.01 compared with all other groups) in patients whose LA corrected between 12 and 24 hours, and 65.9% (n = 57; p < 0.01 compared with all other groups) in patients who corrected after 24 hours. Among the patients with infections, there were 276 infection sites with 42% of infections involving the lung and 21% involving bacteremia. There was no difference in proportion of infections occurring at each site between groups. The mortality rate of patients who developed infections was 7.9% versus 1.9% in patients without infections (p < 0.05). Of the patients who developed infections, 69.8% versus 25.8% (p < 0.001) did not have their lactate levels normalized within 12 hours of emergency room admission. Logistic regression demonstrated that both the Injury Severity Score and OH > 12 hours were independently predictive of infection.

Conclusion: A clear increase in infections occurred in patients with OH whose lactate levels did not correct by 12 hours, with an associated increase in length of stay, days in surgical/trauma intensive care unit, hospital charges, and mortality.