Epidural ropivacaine versus epidural morphine and the catabolic response to colonic surgery: stable isotope kinetic studies in the fasted state and during infusion of glucose.
BACKGROUND
The authors examined the hypothesis that epidural administration of local anesthetic, in contrast to epidural analgesia with morphine, inhibits postoperative protein oxidation during administration of glucose.


METHODS
Fourteen patients were randomly assigned to undergo a 6-h stable isotope infusion study (3 h fasted, 3 h feeding with 4 mg.kg(-1).min(-1) glucose) on the second day after colorectal surgery using epidural analgesia with either continuous ropivacaine or intermittent morphine. Protein synthesis, breakdown and oxidation, and glucose production were measured by L-[L-13C]leucine and [6,6-2H2]glucose. Substrate oxidation rates were determined by indirect calorimetry. Plasma concentrations of metabolic substrates and hormones were also measured.


RESULTS
Whole body protein breakdown, oxidation, synthesis, and glucose production in the fasted state were similar between the two groups. Glucose administration decreased protein breakdown (P = 0.01), protein synthesis (P = 0.001), and glucose production (P = 0.001) to the same extent in both groups, whereas protein oxidation was not significantly affected. The type of epidural analgesia did not significantly influence the circulating concentrations of metabolic substrates and hormones in the fasted or in the fed state. Carbohydrate oxidation rate in the ropivacaine group was greater than in patients receiving morphine (P = 0.04), regardless of whether glucose was infused.


CONCLUSIONS
Epidural analgesia achieved with ropivacaine or morphine does not suppress the catabolic response to surgery, either under fasting conditions or in the presence of an energy supply.
Schricker
Thomas
T
Department of Anesthesia, McGill University, Montreal, Quebec, Canada. thomas.schricker@mcgill.ca
Wykes
Linda
L
Eberhart
Leopold
L
Lattermann
Ralph
R
Carli
Franco
F
D000328:Adult; D000368:Aged; D000577:Amides / Q000494:pharmacology*; D015360:Analgesia, Epidural; D003106:Colon / Q000601:surgery*; D005215:Fasting; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism*; D011659:Pulmonary Gas Exchange; D000077212:Ropivacaine
D000577:Amides; D011506:Proteins; D009020:Morphine; D000077212:Ropivacaine; D005947:Glucose