Effect of halothane and halothane-nitrous oxide on hematocrit and plasma protein concentration in dog and monkey.

Hematocrit and plasma protein concentration in healthy dogs and monkeys (Macaca arctoides) awake and anesthetized with halothane-oxygen and halothane-nitrous oxide oxygen were compared during conditions of spontaneous and controlled ventilation. Both hematocrit and plasma protein concentration decreased within 15 minutes following anesthetic induction. This decrease persisted throughout constant- or variable-depth anesthesia and did not vary appreciably with ventilation, anesthetic dose, or introduction of nitrous oxide. Plasma volume, determined by a dye dilution technique, concomitantly increased. This increase is compatible with the directional changes in hematocrit and plasma protein.