Factors predisposing to wound infection in cardiac surgery. A prospective study of 517 patients.

Postoperative wound infection can greatly prolong hospital stay after cardiac surgery, so the identification of predisposing factors may help in prevention or early institution of treatment. Transfer of organisms from the leg to the sternum during coronary artery surgery has been proposed as a major additional cause of sepsis. The definition of wound infection is not standardised and therefore makes comparison between centres difficult. In a prospective study of 517 patients, a wound scoring method (ASEPSIS) has been used to register all abnormal wounds to maximise the chances of identifying factors predisposing to infection. Abnormal healing was noted in 99 (19%) sternal wounds and 29 (8%) leg wounds. Obesity was the principal risk factor (P less than 0.005). Diabetes, reoperation, length of preoperative hospital stay, age, sex, or previous cardiac surgery had little effect on wound healing. The range of bacteria isolated from chest wounds after coronary artery surgery was similar to that after valvular surgery, but the rate of isolation was significantly greater. With careful attention to technique, leg wound infection rarely presented a clinical problem and did not appear to be a source of bacteria infecting the chest wound.