title: Hormonal and metabolic responses during coronary artery bypass surgery: role of infused glucose.
abstract: Anesthesia, surgery, and hypothermia are conventionally considered the major stress factors in the metabolic and hormonal responses to cardiac surgery. We compared these responses in 14 nondiabetics during and for 24 h after coronary artery bypass surgery; 8 received cardioplegic solutions (C+), and 6 did not (C-). The mean intraoperative glucose load in C+ was 106 g compared to 32 g in C-; postoperatively both groups received 50 g. Marked hyperglycemia (31.8 +/- 4.8 mmol/L) occurred during hypothermia in C+, but dropped to 18.9 mmol/L before surgery ended and to 11.2 +/- 1.1 mmol/L by 2 h postop. In contrast, C- showed constant mild hyperglycemia of 8.3-9.8 mmol/L throughout, significantly less than C+ until 1 h postop. Insulin was suppressed by 55% only during hypothermia, peaking with rewarming in C+ at 2,849 +/- 911 vs. 639 +/- 251 pmol/L in C- (P less than 0.05); as with glycemia, values were comparable after 2 h postop. The pancreatic beta-cell thus responded to hyperglycemia during restoration of normothermia, resulting in a rapid decline in glycemia. This occurred despite elevations in antiinsulin factors in both groups; GH was 14 +/- 4 micrograms/L, cortisol was 607 +/- 38.6 nmol/L, norepinephrine was 11.5 +/- 3.7 nmol/L, epinephrine was 13,863 +/- 3,875 pmol/L, and FFA were 0.36 +/- 0.05 g/L. Early postop, a secondary rise in stress hormones occurred in both groups. Maximal cortisol values were at 4 h (1,186 +/- 140 nmol/L) and peaks of norepinephrine (6.50 +/- 1.66 nmol/L), epinephrine (7,969 +/- 3,602 pmol/L), and FFA (0.27 +/- 0.03 g/L) occurred. The only significant glucagon elevation was at 24 h (C+, 464 +/- 53 ng/L; C-, 350 +/- 241 ng/L; P less than 0.02), Thus, 1) many metabolic responses during coronary artery bypass surgery are influenced by the glucose-containing cardioplegic solution; 2) hypothermia suppresses insulin secretion, but it responds thereafter despite marked elevations of catecholamines, and is associated with decreasing glycemia despite elevated antiinsulin factors; 3) a lesser but highly significant stress response corresponds to awakening from anesthesia; and 4) glucagon plays a minor role in intraoperative hyperglycemia; the rise at 24 h is unexplained.
authors.affiliation: Department of Medicine, Toronto General Hospital, University of Toronto, Ontario, Canada.
authors.forename: M R
authors.initials: MR
authors.lastname: Werb
authors.forename: B
authors.initials: B
authors.lastname: Zinman
authors.forename: S J
authors.initials: SJ
authors.lastname: Teasdale
authors.forename: B S
authors.initials: BS
authors.lastname: Goldman
authors.forename: H E
authors.initials: HE
authors.lastname: Scully
authors.forename: E B
authors.initials: EB
authors.lastname: Marliss
mesh_terms: D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D002395:Catecholamines / Q000097:blood; D001026:Coronary Artery Bypass; D005227:Fatty Acids / Q000097:blood; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D013006:Growth Hormone / Q000097:blood; D006728:Hormones / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D006943:Hyperglycemia / Q000209:etiology / Q000378:metabolism*; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood; D007432:Intraoperative Period; D007773:Lactates / Q000097:blood; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011773:Pyruvates / Q000097:blood; D013312:Stress, Physiological / Q000097:blood* / Q000209:etiology
chemical_list: D001786:Blood Glucose; D002395:Catecholamines; D005227:Fatty Acids; D006728:Hormones; D007328:Insulin; D007773:Lactates; D011773:Pyruvates; D013006:Growth Hormone; D005947:Glucose; D006854:Hydrocortisone