Postoperative sternal dehiscence in obese patients: incidence and prevention.

Background: Obesity has been identified as the single most important risk factor for postoperative sternal infection in coronary bypass surgery patients. It is also a major risk factor for sternal dehiscence, with or without infection, for any type of cardiac operation. We assessed whether prophylactic measures could prevent this complication.

Methods: Two studies were conducted. In study A, 3,158 heart surgery patients were analyzed at 3 cardiac units. Obesity was defined as body mass index (BMI) more than 30. Group I (1,253 obese [39.7%]) was compared with group II (1,905 nonobese [60.3%]). Sternal closure was done at the surgeon's preference: (a) plain wires through and through the bone; (b) peristernal figure-of-eight wires; or (c) peristernal method, using stainless-steel cables. In study B, 123 obese patients were prospectively divided into 2 subgroups. Group B-1 (54 patients) underwent lateral prophylactic sternal reinforcement before placement of peristernal wires. Group B-2 (69 patients) had standard sternal closure, as in study A.

Results: In study A, group I had 81 dehiscences (6.46%); 78 also suffered deep sternal infection and mediastinitis (96%). Despite treatment, dehiscence recurred in 13, and mortality was 38.4%. In group II nonobese patients, 31 dehisced (1.6%, p = 0.000), with no mortality. In study B, group B-1 (54) had 0% dehiscence versus group B-2 (69) with 6 dehiscences (8.7%).

Conclusions: In our study, the rate of obesity is high ( approximately 40%). Sternal dehiscence is real when the BMI is more than 30 (6.46%), and has high morbidity and mortality. Prophylactic sternal reinforcement seems to prevent this complication.