Effects of ketamine on the circulatory functions and body tissue oxygenation in dogs under normal and hypovolemic conditions.
Anesthetic induction with ketamine may cause cardiovascular (CV) stimulation and depression. The study was conducted in dogs to evaluate the dependence of ketamine-induced CV effects upon the dosage, mode of administration and experimental hypovolemic conditions. Slow ketamine infusion (n = 12) at 3 dose levels (5 mg/kg/min for 1, 2 and 4 min to a total dose of 5, 10 and 20 mg/kg) consistently increased the arterial pressure (AP) and heart rate (HR). Rapid bolus injections at 5, 10 and 20 mg/kg (n = 16) produced biphasic changes--decreases followed by increases in AP and HR. Profound depressor and bradycardic responses were readily observed with large dose, rapid bolus injection and during hemorrhagic hypotension. The striking CV depression in some cases became irreversible and led to death. Further study in 8 open-chest dogs revealed that ketamine infusion (a total dose of 10 mg/kg) caused slight increases in cardiac output (CO) and tissue oxygen uptake (VO2). However, the marked depressor response to bolus injection was associated with decreases in CO, total peripheral resistance, stroke volume and VO2. These inhibitory effects were prolonged after hemorrhagic hypotension. In a few cases, CO and VO2 became severely and progressively depressed and death ensued shortly following the injection.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003864:Depression, Chemical; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007022:Hypotension / Q000378:metabolism / Q000503:physiopathology; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D012769:Shock / Q000378:metabolism / Q000503:physiopathology*
D007649:Ketamine; D010100:Oxygen