title: Do on- and off-pump coronary bypass surgery differently affect perioperative peripheral tissue metabolism?
abstract: BACKGROUND
  Microdialysis allows the in-vivo assessment of interstitial fluids. We studied the metabolic status of peripheral tissues (skeletal muscle) in patients undergoing coronary artery bypass surgery on- (CABG) or off-pump (OPCAB).
  
  
  METHODS
  Twenty patients candidates to elective coronary bypass surgery were randomly assigned to undergo CABG or OPCAB. A microdialysis catheter was inserted in the left deltoid muscle before surgery and left in place for 24 hours, and metabolic markers of peripheral tissue perfusion (glucose, lactate, pyruvate, glycerol and lactate/pyruvate (L/P) ratio) were assessed before, at the end, and 24 hours after surgery.
  
  
  RESULTS
  Preoperative clinical features were similar in both groups. Interstitial levels of glucose and lactate increased over time, being in both groups significantly higher than baseline 24 hours after surgery, whereas glycerol levels did not change over time and between groups. In addition, there was an increase over time of pyruvate levels which were significantly higher in CABG after surgery, whereas L/P ratio was significantly higher in OPCAB 24 hours after surgery.
  
  
  CONCLUSIONS
  Metabolic changes after coronary bypass surgery occur with some differences related to CPB use. Overall, these changes suggest that, after coronary surgery, a certain degree of hypermetabolic state ensues, lasting up to 24 hours after surgery; the postoperative increase in pyruvate levels in CABG patients, together with the changes in L/P ratio occurring only in OPCAB patients implies an higher risk of tissue hypoperfusion/ischemia for patients submitted to OPCAB, although this does not lead to permanent cellular damage, as the markers of this complication (e.g., glycerol) do not change over time.
authors.affiliation: Institute of Anesthesiology and Intensive Care, Medical School, University of Sassari, Italy.
authors.forename: A P
authors.initials: AP
authors.lastname: Cossu
authors.forename: S
authors.initials: S
authors.lastname: Suelzu
authors.forename: P
authors.initials: P
authors.lastname: Piu
authors.forename: M
authors.initials: M
authors.lastname: Orecchioni
authors.forename: G
authors.initials: G
authors.lastname: Bazzu
authors.forename: G
authors.initials: G
authors.lastname: Padua
authors.forename: M
authors.initials: M
authors.lastname: Portoghese
authors.forename: P A
authors.initials: PA
authors.lastname: Serra
authors.forename: G
authors.initials: G
authors.lastname: Susini
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000758:Anesthesia; D015415:Biomarkers; D001786:Blood Glucose / Q000378:metabolism; D001026:Coronary Artery Bypass; D047549:Coronary Artery Bypass, Off-Pump; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008660:Metabolism / Q000502:physiology; D017551:Microdialysis; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D059035:Perioperative Period; D011184:Postoperative Period; D019289:Pyruvic Acid / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D019344:Lactic Acid; D019289:Pyruvic Acid