Glycemic Control and Surgical Site Infection Incidence Among Liver Transplantation Recipients

The Surgical Site Infections (SSI's) are the most frequent healthcare-associated infections and are an important infectious complication in the postoperative period among liver transplantation (LT) recipients. SSI incidence among LT recipients, whose allografts were from deceased donors, varied from 9.6% to 35.5% according to a recent literature review. In general surgical procedures, SSI increases the length of stay, morbidity and healthcare costs. Besides that, among LT recipients SSI can raise the risks of the allografts dysfunctions, acute rejections and as a consequence a reduction in the recipient's survival.

There are several risk factors for SSI among LT recipients. There is a relationship among supply sterilization quality, the characteristics of surgical procedure, the operation room environment as well as the allograft's and recipient's conditions and SSI occurrence. In regard to LT recipients, results from previous research highlighted hyperglycemia as an important independent predictor of SSI. Furthermore, regarding this population, it is known from observational studies that LT recipients affected by hyperglycemia are exposed, approximately, to three times the risk of SSI comparatively to LT recipients not exposed.

The concern about maintaining normoglycaemia in acute care facilities is not recent; several studies have been done including on clinical and surgical patients from some medical specialities showing the morbidity and mortality reduction throughout the adoption of strict glycaemic control protocols.

However, among critical surgical patients the LT recipients are highlighted; since they are exposed to impairment in blood glucose metabolism in the perioperative period as a consequence of an intraoperative acute stress state, blood loss and transfusions, the reperfusion phase, use of glucocorticoids and catecholamines.

Results from previous studies pointed the hyperglycaemia among LT recipient as a frequent complication, 94% of them presented it at least once in the transplantation's postoperative period.

The high blood glucose levels can produce electrolyte and acid-base disturbances besides altered plasmatic distribution of sodium. There are impairments to the white blood cells activities, such as reduction in the adherence, chemotaxis, phagocytosis and superoxide formation. Lymphocytes apoptosis combined with T-cell activities suppression besides attenuation of immunoglobulin's work as a consequence of glycosylation.

In spite of evidence from laboratory studies that indicate remarkable impairments caused by hyperglycemia in immune model animals immunologic system, uncertainties remain to evaluate the glycaemic control as a strategy for SSI prevention. Analysing the guidelines to prevent SSI published by World Health Organization, Centers for Disease Control and Prevention (United States of America), National Institute for Health and Care Excellence (United Kingdom), Society for Healthcare Epidemiology of America (United States of America) and Brazilian Health Regulatory Agency conditional recommendation regard the adoption of strategies to strict glycaemic control in the postoperative phase, besides there is no consensus about how glycaemic level could work as a protective factor for SSI among patients who underwent general surgeries.

Moreover, there have been few investigations evaluating the hyperglycaemia effects or blood glucose control in the postoperative phase of LT recipients. Besides the few studies concerned on the topic among LT recipients, the majority of them were observational studies, designed as retrospective cohorts, which could compromise the body's evidence quality. Also, in the previous studies enrolled patients underwent liver-kidney transplantation, which can cause a negative impact on the effects of glycemic control analyses and there is research where recipients presented lower means of Model for End-Stage Liver Disease (MELD) from 19.0 to 28.2 that are lower MELD means than the observed in Brazilian transplantation centres. Finally, we observed the absence of clear criteria for SSI diagnosis in some studies.

It is known that the preoperative screening in living donor LT of donors and recipients as baseline characteristics are different of LT whose allografts came from deceased donors; for instance, liver-kidney recipients who undergo to distinct immunosuppression schemes. Furthermore, lower MELD scores represent LT recipients that could be exposed to diverse risk factors for SSI when compared to LT recipients who the MELD score is higher.

Thus, it sounds appropriate that research aiming to evaluate the effect of strict blood glucose control on SSI incidence among LT recipients should be made. In addition, nurse-initiated blood glucose control protocols, among critically ill patients, are frequently developed. And, a recent literature review pointed to the lack of prospective studies that addressed the evaluation of the outcomes of strict glycaemic control among LT recipients on SSI incidence.

The study hypothesis is: the postoperative strict glycaemic control reduces the SSI incidence among LT recipients.