Tidal volume selection in volume-controlled ventilation guided by driving pressure versus actual body weight in healthy anesthetized and mechanically ventilated dogs: A randomized crossover trial.

Objective: To compare static compliance of the respiratory system (C _stRS ) and the ratio of partial pressure of end-tidal to arterial carbon dioxide (Pe'CO ₂ /PaCO ₂ ), in healthy dogs using two approaches for tidal volume (V _T ) selection during volume-controlled ventilation: body mass based and driving pressure (ΔPaw) guided.
Study Design: Randomized, nonblinded, crossover, clinical trial.
Animals: A total of 19 client-owned dogs anesthetized for castration and ovariohysterectomy.
Methods: After a stable 10 minute baseline, each dog was mechanically ventilated with a V _T selection strategy, randomized to a constant V _T of 15 mL kg ^-1 of actual body mass (V _TBW ) or ΔPaw-guided V _T (V _TΔP ) of 7-8 cmH ₂ O. Both strategies used an inspiratory time of 1 second, 20% end-inspiratory pause, 4 cmH ₂ O positive end-expiratory pressure and fraction of inspired oxygen of 0.4. Respiratory frequency was adjusted to maintain Pe'CO ₂ between 35 and 40 mmHg. Respiratory mechanics, arterial blood gases and Pe'CO ₂ /PaCO ₂ were assessed. Continuous variables are presented as mean ± SD or median (interquartile range; quartiles 1-3), depending on distribution, and compared with Wilcoxon signed-rank tests.
Results: The V _T was significantly higher in dogs ventilated with V _TΔP than with V _TBW strategy (17.20 ± 4.04 versus 15.03 ± 0.60 mL kg ^-1 , p = 0.036). C _stRS was significantly higher with V _TΔP than with V _TBW strategy [2.47 (1.86-2.86) versus 2.25 (1.79-2.58) mL cmH ₂ O ^-1 kg ^-1 , p = 0.011]. There were no differences in Pe'CO ₂ /PaCO ₂ between V _TΔP and V _TBW strategies (0.94 ± 0.06 versus 0.92 ± 0.06, p = 0.094). No discernible difference in ΔPaw was noted between the strategies.
Conclusions and Clinical Relevance: While no apparent difference was observed in the Pe'CO ₂ /PaCO ₂ between the V _T selection strategies employed, C _stRS significantly increased during the V _TΔP approach. A future trial should explore if V _TΔP improves perioperative gas exchange and prevents lung damage.
(Copyright © 2024 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)