Low tidal volume ventilation in healthy dogs.

OBJECTIVE: To determine if low tidal volume (V(T) ) ventilation is associated with the development of respiratory acidosis and changes in lung function in healthy dogs.
DESIGN: Randomized prospective experimental cross-over study.
SETTING: Pulmonary function laboratory at a university teaching hospital. ANIMALS: Five healthy Beagle dogs.
INTERVENTIONS: Dogs were anesthetized and randomly mechanically ventilated with V(T) of 6, 8, 10, 12, and 15 mL/kg while maintaining a constant minute volume.
MEASUREMENTS AND MAIN RESULTS: Arterial blood gases and pulmonary mechanics were collected after 15 minutes of equilibration at each V(T). Repeated measures ANOVA was used to determine the effect of V(T) with a P-value of <0.05 considered significant, and a Pearson product moment was used to determine correlation between V(T) and pH and PaCO(2). V(T) had a significant effect on PaCO(2) (P < 0.001) and on pH (P < 0.001) with lower V(T) being associated with higher PaCO(2) and lower pH. There was a strong correlation between V(T) and PaCO(2) (r = -0.87) and V(T) and pH (r = 0.83). Increased airway pressures and pulmonary compliance were associated with increasing V(T).
CONCLUSIONS: There is a predictable decrease in the pH, decrease in airway pressure, decrease in compliance, and increase in the PaCO(2) associated with lower V(T). Low V(T) ventilation is well tolerated in healthy dogs; the role of low V(T) ventilation in dogs with acute lung injury/acute respiratory distress syndrome as well as the influence of positive end expiratory pressure requires further evaluation. © Veterinary Emergency and Critical Care Society 2012.