Ketamine cardiovascular effects

Although ketamine produces direct myocardial depression, it has significant indirect cardiovascular effects through sympathomimetic effects and stimulation of the vasomotor centre. The heart rate and systolic blood pressure increase by 30% and occasionally up to 100%. Owing to the increased cardiac work and myocardial consumption, ketamine adversely affects the balance between myocardial oxygen supply and demand. Consequently, it is not recommended for use as the sole agent in adults with severe cardiovascular disease. However, the same haemodynamic effects, particularly the raised systemic vascular resistance, make the agent particularly suitable for children with cyanotic heart disease. 

In 190 patients taking tricyclic antidepressants that could not be discontinued before surgery, who underwent general and 61 local or regional anesthesia, there were no changes in the cardiovascular effect of halothane, induction time with pentobarbital, propanidid, or ketamine, or the duration of depolarization or recovery time (160). The general conclusion was that it is safer to continue treatment with tricyclic antidepressants than to risk potential disruption from withdrawal before surgery. 

Waxman K, Shoemaker WC, Lippmann M. Cardiovascular effects of anesthetic induction with ketamine. Anesth Analg 1980 59(5) 355-8. 

Sams R, Pizzo P 1987 Detection and identification of ketamine and its metabolites in horse urine. Journal of Analytical Toxicology 11 58-62 Sarazan R D, Starke W A, Krause G F et al 1989 Cardiovascular effects of detomidine, a new U2-adrenoceptor agonist, in the conscious pony. Journal of Veterinary Pharmacology and Therapeutics 12 378-388... 

Cardiovascular System Unlike other anesthetics, induction doses of ketamine typically increase blood pressure, heart rate, and cardiac output. The cardiovascular effects are indirect and are most... 

Among the drugs which are known to interact with barium, the barbiturates sodium pentobarbital and phenobarbital were found to have an increased depressive effect on the hearts of rats exposed to barium (Kopp et al. 1985 Perry et al. 1983, 1989). This hypersensitivity of the cardiovascular system to anesthesia was not observed in similarly treated animals that were anesthetized with xylazine plus ketamine. Results of the study indicated that the hypersensitivity was specific to the barbiturates and not a generalized effect of anesthesia (Kopp et al. 1985). 

The pharmacological effects of tiletamine plus zolazepam are very similar to the effects produced by ketamine. When used as the sole anesthetic in the horse, tiletamine plus zolazepam can cause excitation and hyperresponsiveness. This combination is only used in the horse after adequate sedation. In general, it produces a dose-related loss of consciousness, characterized as a cataleptic state, and analgesia. Ocular and airway reflexes are well maintained. The combination induces mild cardiovascular stimulation secondary to centrally mediated sympathetic nervous system stimulation. There is minimal respiratory depression. 

Ketamine is a potent analgesic-anesthetic that is also effective intramuscularly. One particular property, production of cardiovascular stimulation, is of special advantage in elderly patients and those in shock (e.g., from bums). However, its propensity to precipitate hallucinations, delirium, disorientation, and other perceptual illusions postoperatively in about 12% of patients has led to its infrequent use in the United States. Ketamine s close structural analogy to the notorious and dangerous hallucinogen, phencyclidine (PCP, angel dust ), should be noted. This drug, which was first also introduced as an... 

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