Obesity is known to increase the risk of surgical procedures (1
), but little data are available regarding the risks of obesity associated with renal transplantation. In 1986 Pasulka et al. outlined areas in which obesity increased surgical risk. These1 included anesthetic problems of airway control and venous access problems; impaired lung function in approximately one third of obese patients (9
); an increase in cardiac stroke work leading to circulatory problems (10
), thromboembolic, and wound complications; and technical considerations, including exposure, hemostasia, anastomotic function, and wound apposition (1
). The overall operative mortality has not been shown to be significantly increased in obese patients undergoing various surgical procedures. Trends however toward higher mortality rates in obese patients have been repeatedly noted (1
). Small numbers of patients in all these studies may compromise the statistical results. We have shown a significantly decreased patient survival during the initial hospital period in the obese patients.
Complications in the areas of anesthesia (1 technical complication of venous-access placement in an obese patient) and respiratory insufficiency (reintubation, required in 16%, ), as suggested by Pasulka (1
), were seen in our obese patients. Additionally, complications of increased stroke work were plausible in 2 control patients and 4 obese patients. Postoperative pulmonary edema occurred as a result of fluid administration in the setting of end-stage renal disease, most often in patients with some degree of myocardial dysfunction. Ultrafiltration therapy resolved the problem in all cases. Admission to an intensive care unit was more common in the obese group (20% vs. 2%) and was prompted by the need for reintubation (8 patients, 4 with associated sepsis) in most instances. Two obese patients required ICU admission for cardiovascular reasons. In 1 case this was due to a perioperative myocardial infarction and in another, a supraventricular arrthymia.
The most frequently reported postoperative complication in obese patients is wound infection (2
) and wound disruption (2
). Postlethwait has suggested that longer operations (due to technical difficulties), increased trauma to the abdominal wall from vigorous retraction, the low resistance of fat to infection, and an inability to obliterate dead space in the abdominal wall fat are all contributing factors (3
). The increased wound area in obese patients has also been postulated as a major factor leading to higher rates of wound infection in these patients (12
). We observed a significantly higher incidence of wound complications in our obese patients (20% vs. 2% in the nonobese patients, P
≤0.01) and also noted longer operations in the obese group. Transplant nephrectomy, urine leak, and hematoma are associated with a higher incidence of wound infection in the transplant population (13
). The single wound complication in the control group was associated with a urine leak. Four of the 10 wound complications seen in the obese group occurred after transplant nephrectomy, and one followed a wound hematoma. The remaining five, however, may reflect the combined negative effects of prolonged surgery and the low resistance of fat to infection (3
). The latter factor may be amplified in the immunosuppressed state that accompanies renal transplantation.
Acute colonic ileus is a recognized complication of renal transplantation aod is often a serious cause of morbidity and mortality from cecal perforation (15
). Two obese patients died of sepsis related to cecal perforation caused by Ogilvie's t syndrome, but no statistical differences in rates of colonic complications were noted between the obese and control groups.
Steroid-induced diabetes has long been recognized in the posttransplant population (17
). The insulin resistance and impaired glucose tolerance seen with obesity (18
), combined with steroid immunosuppression may exacerbate this metabolic iff derangement in obese transplant recipients. The additional hyperglycemic effects of CsA (20
), presumably via impaired insulin secretion (22
), warrants further study in this group of patients.
Initial graft function and long-term graft survival (, ) were both significantly worse in the obese patients. The reasons for these observations remain speculative and require prospective study. Factors such as longer graft warm ischemia time, due to the technical challenge the vascular anastomoses offer and, secondly, possible altered CsA pharmacokinetics in obese patients may both contribute to lower paft survival. Postoperative complications in the obese patients occurred significantly more often than in the control patients and no doubt contributed to poorer graft survival in the former group of patients.
Since each patient was matched for demographic characteristics, obesity was identified as an independent risk factor for successful renal transplantation. Mortality during the initial hospital period was increased in the obese population. More wound complications and an increased need for insulin therapy occurred in obese versus control patients. Serious complications requiring ICU admission and reintubation were also more frequent in this group of patients. In addition to higher rates of postoperative complications and longer hospital stays, graft function in these patients was significantly worse than in the control population. All these observations suggest that preoperative weight reduction should be stressed in obese patients prior to kidney transplantation. Furthermore, additional study is needed in order to elucidate the factors contributing to poorer graft survival in obese patients.