P140 | POSTOPERATIVE PNEUMONIA FOLLOWING CABG IS PREDICTABLE BY PREOPERATIVE TRACHEAL ASPIRATES BUT CANNOT BE PREVENTED BY PROLONGED ANTIBIOTIC PROPHYLAXIS |
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| University of Bern, Bern, Switzerland | |
Objective: To assess the value of preoperative tracheal aspirates in predicting the risk of postoperative pneumonia after coronary artery bypass grafting, to clarify if preoperative bacteriological studies have any prognostical value during early postoperative course and to evaluate the efficacy of a prolonged perioperative antibiotic prophylaxis in patients at risk for postoperative pneumonia.
Methods: Tracheal aspirates of 500 patients undergoing cardiac surgery were taken immediately after intubation and analyzed for microorganisms by Gram-stain and semi-quantitative microbiological cultures. All patients received 2 g ceftriaxone as a single dose perioperative prophylaxis prior to surgery. Results of the Gram-stains were available before the patient was transferred to the intensive care unit. After the results were known, both groups of patients (positive Gram-stain = group I, negative Gram-stain = group II) were randomly assigned to either simple antibiotic prophylaxis [A] (Ceftriaxone 2 g on postop. day 1) or prolonged antibiotic prophylaxis [B] (Ticarcillin + Clavulanic acid 3 × 5.2 g during 72 hours).
Results:
| Group IA | Group IB | Group IIA | Group IIB | |
| Tracheal aspirate positive | 44 | 47 | ||
| Tracheal aspirate negative | 204 | 205 | ||
| Pneumonia | 6 (13%) | 8 (17%)* | 6 (2%) | 9 (4%) |
| Identical microorganisms | 6/6 (100%) | 7/8 (87%)* | 2/6 (33%) | 5/9 (55%) |
| Smoking | 37/44 (84%) | 38/47 (80%)* | 95/204 (46%) | 110/205 (53%) |
| Smoking and pneumonia | 6/6 (100%) | 6/8 (75%) | 4/6 (66%) | 7/9 (77%) |
| Respiratory dysfunction | 16/44 (36%) | 11/47 (23%)* | 28/204 (13%) | 37/205 (18%) |
| Respiratory dysfunction + | ||||
| pneumonia | 4/6 (75%) | 5/8 (62%) | 3/6 (50%) | 6/9 (66%) |
* p < 0.05 between Group I and II, no statistical difference between A and B
Conclusions: Early postoperative pneumonia (<5 d.) is probably almost always caused by microorganisms that colonize the respiratory tract before operation. The risk of developing early pulmonary infection after cardiac surgery can be predicted from the preoperative tracheal aspirates. Prolonged perioperative antibiotic prophylaxis does not allow any reduction of the incidence of pulmonary infections. Better control of risk factors prior to surgery (abstention from smoking and treatment of significant pulmonary disease) remains essential to prevent postoperative pneumonia.
