DECREASED MORTALITY-RATE AND LENGTH OF HOSPITAL STAY IN SURGICAL INTENSIVE-CARE UNIT PATIENTS WITH SUCCESSFUL SELECTIVE DECONTAMINATION OF THE GUT

Objective. Current studies concerning selective decontamination of the digestive tract have failed to demonstrate a decrease in the length o f hospital stay and mortality rate, despite the finding of a significa ntly lower number of infections. To evaluate this issue in more detail , the relationship between the mortality rate and length of stay with respect to colonization and infections was studied within a group of p atients receiving selective decontamination. Special attention was giv en to the efficacy of decontamination within each patient. The main qu estion addressed was whether an effect on mortality rate was present, and if so, why this effect was not apparent until now. Design: Prospec tive observational cohort study. Setting. Surgical intensive care unit (ICU) in a university hospital. Patients: Ninety-seven patients prima rily admitted into the surgical ICU who received selective decontamina tion. Transferred patients were excluded. The majority of the surgerie s were elective, and all patients completed the follow-up. Interventio ns: All patients received polymyxin E, amphotericin B, and norfloxacin four times a day in a 2% solution of Orabase(R) orally and enterally as suspensions of 200, 500, and 50 mg, respectively. Assessment of the efficacy of selective decontamination was done by identification of G ram-negative microorganisms in surveillance cultures from the orophary nx and rectum. Predicted mortality rates for each patient were calcula ted with a logistic regression formula. Measurements and Main Results. A possible benefit of selective decontamination of the digestive trac t would be expressed by lower actual mortality rates compared to predi cted mortality rates. Since we expected the efficacy of decontaminatio n to have an influence on infection and mortality rates, we evaluated these rates in terms of successful or unsuccessful decontamination. Mo st patients (n = 72) were successfully decontaminated. Actual death ra tes in these patients were significantly lower than the expected rates (as calculated by the Acute Physiology and Chronic Health Evaluation [APACHE] II scoring system) (18% vs. 40%, p = .006), whereas no differ ence was found in those patients with failed decontamination (n = 25, death rate 44%). The patients with unsuccessful selective decontaminat ion had significantly longer hospital (52 vs. 34 days) and ICU lengths of stays (23 vs. 9 days;p =.002) and higher mortality rates (44% vs. 18%, p =.020) when compared with those patients who were successfully decontaminated. Conclusions: These results indicate that selective dec ontamination is beneficial in terms of mortality rate and length of st ay in surgical patients only when successful decontamination has been achieved. The subgroup of patients for whom decontamination is not suc cessful might be responsible for the obscurity in mortality effects of selective decontamination in studies until now. It is expected that i dentification and subsequent elimination of possible risk factors that cause a failure of selective decontamination can result in lower morb idity and mortality rates in critically ill, surgical patients admitte d to the ICU.