O uso pré-operatório da l-alanil–glutamina em pacientes submetidos a revascularização cardíaca com circulação extracorporea e sua repercussão sobre as concentrações séricas de indicadores do estresse oxidativo, de mediadores inflamatórios, de metabolitos e sobre o controle glicemico

Abstract

Recent studies have pointed out the negative effects of persistent hyperglycemia in cardiac surgery patients. Tight glucose control below 110 mg/dL with insulin has been shown to exert anti-inflammatory effects in critically ill patients. Glutamine, a conditionally essential amino acid during stress, has been shown to promote glucose utilization and to increase insulin sensitivity in trauma patients. The present study aimed to access the effects of nutraceutical doses of L-alanyl-glutamine preoperatively in a prospective, randomized, controlled, double-blind study. Twenty-two elective patients (63 ± 8 years) with coronary artery disease scheduled for coronary artery bypass grafting were randomly assigned to receive either saline 1000 ml (Group Saline, n=11) or L-alanyl-glutamine 20% (250ml) in saline to final volume 1000 ml (Group L-alanyl-glutamine, n=11). The infusions were started 3 h prior to the operative procedure and lasted 3 hours. Blood samples were collected 3h before [Basal (T-0)], just before the beginning of the surgical procedure [Preoperative (T-1)], at the onset and at the end of the extra-corporeal perfusion (T-2), and at the end of the surgical procedure (Intraoperative). Additional samples were colleted 12 and 24 h later (Postoperative). The following variables were analysed: Insulin, peptide C, creatine phosphokinase (CPK), lactate deshydrogenase (LDH), high sensibility protein C (PCR), IL-1, IL-6, 1L-10, TNF-α, metabolites (lactate, pyruvate, acetoacetate, 3-hidroxibutyrate), reactive substances to thiobarbituric acid (TBARS), reduced glutathione (GSH) and total antioxidant state (TAS). Glucose level were analysed throught capillary blood sample obtained by digital puncture in the periods T-0, T-1, every hour during surgery (T-2) and every two hours after surgery (T-3). Despite the exogenous insulin infusion rate to be constant in both groups during the operation, insulinemia was kept at similar concentrations at all periods studied in patients who received the dipeptide. On the other hand, control patients increased their insulinemia during the intra (T-2) and post-operative period (T-3) as compared to basal values (T-0) (31.9+/-28.8 Versus 6.56+/-5.4, p=0.013). Glucose increasing plasma concentrations were significantly decreased in L-alanyl-glutamine treated patients during the intraoperative period as compared to control patients (129.9+/-15.2 versus 158.6+/-18.6, p= 0.003). No significant difference were observed between the two groups on plasma concentration of others variables studied. In conclusion, the infusion of nutraceutical doses of L-alanyl-glutamine prior to operative period in patients submitted to coronary artery bypass grafting with extracorporeal perfusion, reduce the glicemic surge compared to control patients, without increasing insulin plasma concentrations as compared to their basal values This prospective study highlights the potential use of preoperative L-alanyl-glutamine administration in heart surgery patients to attain glucose control and to improve insulin sensitivity