Background: Leukocytosis and fever in the absence of infection are common phenomena in post surgical period. The systemic inflammatory response syndrome induced by surgical trauma is a well-known entity, with resultant release of variety of inflammatory cytokines leading to fever and/or leukocytosis in spite of the absence of infection.
Aims and objective: To know the association of leukocytosis and fever with infection in immediate post cardiac surgical period.
Methods: It was a retrospective, observational study including 569 patients, who underwent cardiac surgeries in our institute. All demographic data, comorbidities and other factors associated with fever and/or leukocytosis were analyzed. The sensitivity and specificity of fever and/or leukocytosis were analyzed for the diagnosis of infection.
Results: Out of 569 patients; 49 patients (9%) had evidence of infection on microbiological culture. Mean total leukocyte counts (TLC) on zero and 1st postoperative days were associated with infection with a sensitivity (75.5% and 63.3%) and specificity (15.8% and 24.0%) respectively. Mean maximum temperature (Tmax) on zero and 1st postoperative days were associated with infection with a sensitivity (20.4% and 24.5%) and specificity of (82.5% and 83.3%) respectively. The combined sensitivity and specificity of leukocytosis and fever for the diagnosis of infection on 2nd postoperative day was 14.3% and 91.5% respectively.
Conclusion: Fever and leukocytosis are poor predictors of diagnosing infection on the first two postoperative days. However, fever and leukocytosis combined together have low sensitivity (14.3%) with high specificity (91.5%) for the diagnosis of infection on the 2nd and subsequent postoperative days.