CARDIOVASCULAR EFFECTS OF HALOTHANE IN HORSE

  • 1 January 1978
    • journal article
    • research article
    • Vol. 39  (4) , 611-615
Abstract
Cardiovascular effects of venous alveolar concentrations of halothane in O2 were studied in 8 young, healthy horses under conditions of constant arterial CO2 tension. The alveolar concentration of halothane was expressed as a multiple of the minimal alveolar concentration (MAC) which was known for each animal. Increasing alveolar halothane concentrations to MAC 2.0 resulted in a progressive and significant (P < 0.05) decline in systemic arterial pressure and left ventricular work. Cardiac output decreased between MAC 1.0-2.0 as a result of significantly (P < 0.05) decreased stroke volume. Heart rate, total peripheral resistance, pulmonary arterial pressure, hematocrit, plasma protein concentration, arterial O2 tension and arterial pH remained constant over the same range of anesthetic dosages. Continuation of anesthesia, spontaneous ventilation and the accompanying rise in arterial CO2 tension and electrical stimulation of the horse''s oral mucous membranes produced varying degrees of stimulation of cardiovascular function of MAC 1.5.