Sepsis and septic complications in the surgical patient: who is at risk?

The estimation of patients who are at risk for infection, sepsis, and organ dysfunction/failure is crucial not only for inclusion in treatment algorithms but also for entry into appropriate clinical trials of prophylaxis and therapy. Patients on the surgical service who have sustained major trauma or who have undergone transplantation are clearly at the greatest risk. Other immunosuppressed patients at risk for sepsis include those receiving myelosuppressive chemotherapy, those with overwhelming malignancy, and those who suffer from cirrhosis, diabetes mellitus, and severe malnutrition. We have focused on the trauma patient, in whom infection and organ failure are the leading causes of late death, major morbidity, and prolonged hospital stay. Over a 10 yr period, we have surveyed a number of host defense parameters that pertain to an adequate immune response and found a suppressed response shortly after injury in many. All were anergic to a standard skin test panel, and the duration of anergy varied with the clinical course of infection. Immunoglobulin levels were low after major injury as well as specific antibodies to both Gram-positive and Gram-negative organisms. The ability of serum from the trauma patient to opsonize heat-killed bacteria was markedly depressed 24 h after injury in those patients who subsequently died of infection. Class II major histocompatibility antigen expression on peripheral blood monocytes correlated closely with clinical outcome and led to the development of an Outcome Predictive Score. This score can identify patients within hours of hospitalization who are at risk of subsequently developing overt clinical infection and sepsis. Intervention then can be applied to such at-risk populations prior to the onset of sepsis and to evaluate the efficacy of prophylaxis. Patients in whom prophylaxis fails could be eligible for trials of therapeutic intervention as well.