Objective: To compare the effects of three recruitment airway pressures (RP) 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 and zero positive end-expiratory pressure and 100% oxygen. Three maneuvers consisting of a 30 second inspiration at RPs of 15 (RP15), 25 (RP25) and 35 (RP35) cmHO were performed randomly, 15 minutes apart. Changes in lung aeration and lung deformation were compared with end-expiratory baseline (before the application of each RP) and between-RPs 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 RPs. The amount of hypoaeration and normoaeration during baseline decreased with all RPs (p < 0.001). There was no difference between RPs regarding hypoaeration (all p > 0.999), whereas normoaeration was higher at RP15 than RP25 and RP35 (p < 0.009). Compared with baseline, the fraction of hyperaerated alveoli increased with each RP (p < 0.001) and was lower during RP15 than RP25 and RP35 (both p ≤ 0.007). Global lung strain was lower during RP15 than at higher RP (p < 0.001).
Conclusions And Clinical Relevance: A RP of 15 cmHO for 30 seconds was the recommended RP because it was as effective at reversing hypoaeration as RPs of 25 and 35 cmHO but with less hyperaeration and potential for overdistension of the lungs in this particular population of dogs with negligible atelectasis.
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| http://dx.doi.org/10.1016/j.vaa.2022.06.005 | DOI Listing |
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