The renin--angiotensin--aldosterone system during cardiac surgery with morphine--nitrous oxide anesthesia.
Ten consecutive adult patients undergoing elective cardiac surgery with extracorporeal circulation were anesthetized using morphine (1-3 mg/kg) and nitrous oxide. Pre-bypass plasma renin activity showed a 3.5-fold elevation (P smaller than 0.001) over baseline values. This correlated with maximal blood pressure elevation. Plasma renin activity remained elevated during bypass. High baseline aldosterone levels increased 3.4-fold (P smaller than 0.001) after 15 minutes on bypass and 4.0-fold by the end of bypass. Plasma potassium decreased from 3.9 mEq/1 before bypass to 3.2 mEq/1 (P smaller 0.0001) during bypass, and the fractional urinary excretion of potassium was 32 per cent before bypass with a mean of 34.4 per cent during bypass. Urinary output remained high during bypass despite a progressive decrease in glomerular filtration rate. Catecholamine levels showed no significant change. The data suggest that the renin-angiotensin-aldosterone system may play a role in blood pressure regulation during cardiopulmonary bypass and may result in the excessive urinary excretion of potassium and decrease in plasma potassium levels.
D000769:Anesthesia, Inhalation; D000804:Angiotensin II / Q000097:blood*; D001794:Blood Pressure; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D002395:Catecholamines / Q000097:blood; D005919:Glomerular Filtration Rate; D006801:Humans; D007273:Injections, Intramuscular; D007442:Intubation, Intratracheal; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology; D009609:Nitrous Oxide / Q000494:pharmacology; D009994:Osmolar Concentration; D011188:Potassium / Q000097:blood / Q000652:urine; D012083:Renin / Q000097:blood*; D012601:Scopolamine / Q000008:administration & dosage; D012964:Sodium / Q000097:blood; D014556:Urine
D002395:Catecholamines; D000804:Angiotensin II; D009020:Morphine; D012964:Sodium; D012601:Scopolamine; D012083:Renin; D009609:Nitrous Oxide; D011188:Potassium