Nosocomial pneumonia in patients undergoing heart surgery

Objective: To determine the risk factors related to the presence of postsur gical nosocomial pneumonia (NP) in patients who had undergone cardiac surge ry. Design: A case-control study. Setting: Postcardiac surgical intensive care unit at a university center. Patients: A total of 45 patients with NP and 90 control patients collected during a 4-yr period. Interventions: Pre-, intra-, and postoperative factors were collected and c ompared between two groups of patients (cases vs. controls) to determine th eir influence on the development of NP. The diagnosis of NP was always micr obiologically confirmed as pulmonary specimen brush culture of greater than or equal to 10(3) colony-forming units/mL or positive blood culture/pleura l fluid culture by the growth of identical microorganisms isolated at the l ung. For each patient diagnosed with NP, we selected control cases at a rat io of 1:2. Measurements and Main Results: The incidence of NP was 6.5%. Multivariate a nalysis found a probable association of the following variables with a grea ter risk for the development of NP: reintubation (adjusted odds ratio [AOR] , 62.5; 95% confidence interval [CI], 8.1-480; p =.01); nasogastric tube (A OR, 19.7; 95% CI, 3.5-109; p =.01), transfusion of greater than or equal to 4 units of blood derivatives (AOR, 12.8; 95% CI, 2-82; p =.01) and empiric al treatment with broad-spectrum antibiotics (AOR, 6.6; 95% CI, 1.2-36.8; p =.02). Culture results showed 13.3% of the NP to be of polymicrobial origi n, whereas 77.3% of the microorganisms isolated were Gram-negative bacteria . The mortality (51 vs. 6.7%, p <.01) and the length of stay in the intensi ve care unit (25 +/- 14.8 days vs. 5 +/- 5 days, p <.01) were both greater in patients with NP. Conclusions: We conclude that the surgical risk factors, except the transfu sion of blood derivatives, have little effect on the development of NP. Rei ntubation, nasogastric tubing, previous therapy with broad-spectrum antibio tics, and blood transfusion are factors most likely associated with NP acqu isition.