High spinal anesthesia for cardiac surgery: effects on beta-adrenergic receptor function, stress response, and hemodynamics.
BACKGROUND
This double-blind, randomized, controlled trial examined the effect of high-dose intrathecal bupivacaine in combination with general anesthesia on atrial beta-adrenergic receptor function, the stress response, and hemodynamics during coronary artery bypass graft surgery.


METHODS
Thirty-eight patients were randomized to either control (n = 19) or intrathecal bupivacaine (ITB) groups (n = 19). Patients in the ITB group received 37.5 mg intrathecal hyperbaric bupivacaine before induction of general anesthesia. Control patients received an injection of local anesthetic into the skin and subcutaneous tissues (sham spinal). Comparisons were made between groups with respect to atrial receptor desensitization and down-regulation, in addition to circulating catecholamines and hemodynamics.


RESULTS
In patients with cardiopulmonary bypass (CPB) times in excess of 1 h, the ITB group had significantly less atrial beta-receptor dysfunction, as measured by maximal isproteronol, 50% maximal isoproterenol, sodium fluoride-stimulated activity, and zinterol stimulation assays of adenylyl cyclase activity (P < or = 0.02) and beta-adrenergic receptor density (P = 0.02). Serum epinephrine, norepinephrine, and cortisol concentrations were significantly lower in the ITB group, independent of CPB times (P < 0.0001, P < 0.001, and P < 0.05, respectively). ITB patients had a higher cardiac index and a lower pulmonary vascular resistance index in the post-CPB time period (P < 0.01 and P < 0.05, respectively). In the pre-CPB period, mean arterial pressure and systemic vascular resistance index were significantly lower in the ITB group.


CONCLUSIONS
High-dose intrathecal bupivacaine, when combined with general anesthesia, resulted in less beta-receptor dysfunction and a lower stress response during coronary artery bypass graft surgery.
Lee
Trevor W R
TW
Department of Anesthesia, Health Sciences Center, University of Manitoba, Canada.
Grocott
Hilary P
HP
Schwinn
Debra
D
Jacobsohn
Eric
E
D000262:Adenylyl Cyclases / Q000378:metabolism; D000318:Adrenergic beta-Agonists; D000368:Aged; D000768:Anesthesia, General; D000775:Anesthesia, Spinal / Q000009:adverse effects; D000779:Anesthetics, Local / Q000008:administration & dosage; D002045:Bupivacaine / Q000008:administration & dosage; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002395:Catecholamines / Q000097:blood; D001026:Coronary Artery Bypass; D004311:Double-Blind Method; D015536:Down-Regulation / Q000187:drug effects; D004983:Ethanolamines; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007545:Isoproterenol; D008297:Male; D008875:Middle Aged; D011659:Pulmonary Gas Exchange; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D012129:Respiratory Function Tests; D013312:Stress, Physiological / Q000503:physiopathology*; D016277:Ventricular Function, Left / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D000779:Anesthetics, Local; D002395:Catecholamines; D004983:Ethanolamines; D011943:Receptors, Adrenergic, beta; C002904:zinterol; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D002045:Bupivacaine