LAUSR

OBJECTIVE To evaluate three routinely used tidal volumes (VT; 10, 12 and 15 mL kg-1) for controlled mechanical ventilation (CMV) in lung-healthy anaesthetized dogs by assessing alveolar ventilation (VTalv) and dead space (DS). STUDY DESIGN Prospective, randomized clinical trial. ANIMALS A total of 36 client-owned dogs. METHODS Dogs were randomly allocated to a VT of 10 (G10), 12 (G12) or 15 (G15) mL kg-1. After induction CMV was started. End-tidal carbon dioxide tension was maintained at 4.7-5.3 kPa by changing the respiratory frequency (fR; 630. VTalv kg-1 (p=0.001) increased and VDBohr (p=0.002) decreased with greater VT. VTCO2,br (p=0.017) increased and VDaw/VT (p=0.006), VDBE (p=0.008) and fR (p=0.002) decreased between G10 and G15. PIP (p=0.013) was significantly higher in G15 compared with that in G10 and G12. No changes were observed in MawP. CONCLUSIONS AND CLINICAL RELEVANCE A VT of 15 mL kg-1 is most appropriate for CMV in lung-healthy dogs (as evaluated by respiratory mechanics and VCap) and does not impair cardiovascular variables.