Cardiopulmonary effects of prolonged, constant-alveolar-dose halothane (HAL) and methoxyflurane (MOF) in O2 anesthesia on spontaneously breathing dogs were determined. One hour after anesthetic induction, end-tidal concentration was set at 1.04% HAL or 0.28% MOF [each representing 1.2 minimum alveolar concentration (MAC) for dogs] and maintained for 7 h. No time-related changes were associated with MOF. However, HAL significantly (P < 0.05) elevated cardiac output (Q̇) from 2 to 7 h by increasing stroke volume; mean aortic pressure (MAP) also increased with time (P < 0.05 beginning at 5 h). Four of these dogs were studied again at least 3 wk later at a constant end-tidal dose of 1.48% HAL in O2 (1.7 MAC). Q̇ and MAP were lower initially during 1.7 MAC than during 1.2 MAC but not after 2 h of anesthesia. The greater HAL dose initially depressed ventilation and elevated arterial partial pressure of CO2 (Pa(CO2)) compared with the lower dose. Pa(CO2) continued to increase with duration of 1.7 MAC HAL, as did results of ventilatory gas volume and flow measurements.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Applied Physiology|
|State||Published - 1987|
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation