Low tidal volume ventilation in healthy dogs

Abstract

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. Randomized prospective experimental cross-over study. Pulmonary function laboratory at a university teaching hospital. Five healthy Beagle dogs. 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. 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). 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.