title: Preoperative insulin resistance and the impact of feeding on postoperative protein balance: a stable isotope study.
abstract: BACKGROUND
  Major surgery induces a catabolic state resulting in a net loss of body protein.
  
  
  OBJECTIVE
  Our objective was to compare protein metabolism before and after surgery in nondiabetic patients with and without preoperative insulin resistance (IR). It was hypothesized that the anabolic response to feeding would be significantly impaired in those patients with preoperative insulin resistance.
  
  
  METHODS
  A hyperinsulinemic-euglycemic clamp has been used to identify two groups of patients: IR and insulin sensitive (IS). A tracer kinetics technique has been used to evaluate the metabolic response to food intake in both groups.
  
  
  METHODS
  Patients undergoing cardiopulmonary bypass participated.
  
  
  METHODS
  Ten IS patients and 10 IR patients were enrolled in the study.
  
  
  METHODS
  After an overnight fasting, a 3-h infusion of a solution composed of 20% glucose and of amino acids at a rate of 0.67 and 0.44 kcal/kg · h, respectively, was started in each group. Phenylalanine kinetics were studied at the end of fasting and feeding.
  
  
  METHODS
  Effect of feeding on protein balance before and after surgery was evaluated. Protein balance has been measured as the net difference of protein breakdown minus protein synthesis.
  
  
  RESULTS
  Protein balance increase after postoperative feeding was blunted only in the IR group. In contrast, in the IS group, the postoperative anabolic effect of feeding was the same as before surgery.
  
  
  CONCLUSIONS
  These findings propose a link between insulin resistance and protein metabolism. When non-IR patients are fed, a significant anabolic effect in the postoperative period is demonstrated. In contrast, IR patients are less able to use feeding for synthetic purposes.
authors: Dipartimento di Anesthesia e Rianimazione Ospedali Riuniti di Bergamo, I-24128 Bergamo, Italy. fdonatelli@inwind.it
authors: Francesco
authors: F
authors: Donatelli
authors: Davide
authors: D
authors: Corbella
authors: Marta
authors: M
authors: Di Nicola
authors: Franco
authors: F
authors: Carli
authors: Luca
authors: L
authors: Lorini
authors: Roberto
authors: R
authors: Fumagalli
authors: Gianni
authors: G
authors: Biolo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D002315:Cardiopulmonary Bypass; D004435:Eating / Q000502:physiology*; D002149:Energy Intake / Q000502:physiology*; D005215:Fasting; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010649:Phenylalanine / Q000378:metabolism; D011184:Postoperative Period; D011506:Proteins / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D007328:Insulin; D011506:Proteins; D010649:Phenylalanine