Abstract
Objective
To compare the effects of three recruitment airway pressures (RPaw) on lung aeration and volumes in mechanically ventilated dogs during propofol anesthesia.
Study design
Prospective, crossover randomized experimental study.
Animals
A total of eight healthy anesthetized experimental Beagle dogs in dorsal recumbency.
Methods
Dogs were mechanically ventilated with a tidal volume of 15 mL kg–1 and zero positive end-expiratory pressure and 100% oxygen. Three maneuvers consisting
of a 30 second inspiration at RPaws of 15 (RPaw15), 25 (RPaw25) and 35 (RPaw35) cmH2O were performed randomly, 15 minutes apart. Changes in lung aeration and lung deformation
were compared with end-expiratory baseline (before the application of each RPaw) and between-RPaws using computed tomography scans and calculations of global lung strain. Between-group
comparisons were performed with one-way anova for repeated measures followed by Tukey test for multiple comparisons. A p value < 0.05 was considered significant.
Results
The amount of nonaeration was minimal (<1%) at baseline and not different with the
application of the RPaws. The amount of hypoaeration and normoaeration during baseline decreased with all
RPaws (p < 0.001). There was no difference between RPaws regarding hypoaeration (all p > 0.999), whereas normoaeration was higher at RPaw15 than RPaw25 and RPaw35 (p < 0.009). Compared with baseline, the fraction of hyperaerated alveoli increased
with each RPaw (p < 0.001) and was lower during RPaw15 than RPaw25 and RPaw35 (both p ≤ 0.007). Global lung strain was lower during RPaw15 than at higher RPaw (p < 0.001).
Conclusions and clinical relevance
A RPaw of 15 cmH2O for 30 seconds was the recommended RPaw because it was as effective at reversing hypoaeration as RPaws of 25 and 35 cmH2O but with less hyperaeration and potential for overdistension of the lungs in this
particular population of dogs with negligible atelectasis.
Keywords
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Article info
Publication history
Published online: June 30, 2022
Accepted:
June 24,
2022
Received in revised form:
June 21,
2022
Received:
December 20,
2021
Identification
Copyright
© 2022 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
