title: Cardiovascular effects of intravenous bolus administration and infusion of ketamine-midazolam in isoflurane-anesthetized dogs.
abstract: Cardiovascular effects of IV administered ketamine (10 mg/kg) and midazolam (0.5 mg/kg) were determined in 12 healthy isoflurane-anesthetized (1.7% end-tidal concentration) dogs. Six dogs received a ketamine-midazolam combination (K-M) as a bolus over 30 seconds and 6 dogs received K-M as an infusion over 15 minutes. Ketamine-midazolam combination as a bolus and an infusion caused early significant (P < 0.05) reductions in mean systemic blood pressure, cardiac index, and stroke index, which returned to baseline values near the end of the study. Heart rate decreased significantly (P < 0.05) in dogs of the infusion group and returned to the baseline value near the end of the study. One dog died after K-M bolus administration. Mean maximal decreases from baseline for systemic blood pressure, cardiac index, and stroke index were significantly (P < 0.05) greater in dogs of the bolus group than in dogs of the infusion group; therefore, cardiovascular effects of K-M after infusion were less severe than those after bolus. Base excess and pHa decreased significantly (P < 0.05) in the infusion group, although similar changes occurred in both groups. Four dogs were maintained with 1.7% end-tidal isoflurane to determine temporal effects of isoflurane; these dogs did not receive K-M. Increases in heart rate, cardiac index, stroke index, and left and right ventricular stroke work indexes were significant (P < 0.05) at various sample collection intervals, particularly during the later stages of the study. Isoflurane anesthesia effectively blocked the cardiostimulatory properties of K-M.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843.
authors.forename: J D
authors.initials: JD
authors.lastname: Jacobson
authors.forename: S M
authors.initials: SM
authors.lastname: Hartsfield
mesh_terms: D000284:Administration, Oral; D000769:Anesthesia, Inhalation; D000818:Animals; D002319:Cardiovascular System / Q000187:drug effects*; D004285:Dogs / Q000502:physiology*; D004338:Drug Combinations; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007262:Infusions, Intravenous / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000494:pharmacology*; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D008874:Midazolam / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects*
chemical_list: D004338:Drug Combinations; D007649:Ketamine; D007530:Isoflurane; D008874:Midazolam