Severe sepsis in cardiac surgical patients.

OBJECTIVE: To elucidate the incidence, determinants, and consequences of severe sepsis after cardiac surgery.
DESIGN: Prospective study.
SETTING: Cardiac surgical unit, Greece.
SUBJECTS: 2615 adult patients having cardiac operations. MAIN OUTCOME MEASURES: Microbiological evidence of sepsis, mortality, and duration of stay in the intensive care unit (ICU) and hospital.
RESULTS: Severe sepsis developed in 41/2615 patients (2%), all during their stay in the ICU: there were 30 men and 11 women, mean (SD) age 65 (10) years. It was most common after combined coronary artery bypass grafting and valve-related operations (7/95, 7%), followed by miscellaneous cardiac operations (7/147, 5%), valve replacement (8/359, 2%), and coronary artery bypass grafting (19/2014, 1%). When the 41 patients who developed severe sepsis were compared with those who did not (n = 2574) by univariate analysis, there were significant differences in age (p = 0.004); type of operation (p < 0.0001); duration of operation (p < 0.001); bleeding that necessitating either reoperation or significantly more blood transfused (p < 0.0001); and the incidence of low cardiac output syndrome (p = 0.0001). Of the 41 patients with severe sepsis, 19 (46%) had serious operative complications, 40 (98%) had severe complications in the ICU, and 16 (39%) required reintubation for hypoxaemia. Among the 41 there were 54 bacteraemic episodes of which 37 (69%) were caused by gram positive cocci, 6 (11%) by gram negative bacteria, and 11 (20%) by Candida albicans. Staphylococcus epidermidis was the most common pathogen isolated (n = 26, 48%). Sepsis associated with bacterial infection usually developed during the first two weeks, and that caused by fungal infection was most common after the twentieth postoperative day. Patients with severe sepsis required longer mechanical ventilation (31 (21) days compared with 0.9 (0.1) days); longer stay in the ICU (40 (25) days) compared with 2 (1) days); longer stay in hospital (48 (27) days compared with 10 (2) days); and significantly more of them died (13 (32%) compared with 41 (2%), p < 0.0001 in each case).
CONCLUSIONS: We concluded that severe sepsis mainly developed in cardiac surgery patients with serious operative and postoperative complications and was associated with a longer stay in both ICU and hospital, and a higher mortality.