1. Cardiovascular function, pulmonary gas exchange and tissue oxygenation in isoflurane-anesthetized, mechanically ventilated Beagle dogs with four levels of positive end-expiratory pressure.
- Author
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Soares JHN, Braun C, Machado ML, Oliveira RL, Henao-Guerrero N, Countermash-Ott S, Allen IC, Grant DC, and Giannella-Neto A
- Subjects
- Animals, Cross-Over Studies, Male, Positive-Pressure Respiration veterinary, Prospective Studies, Pulmonary Gas Exchange, Respiration, Artificial veterinary, Dogs physiology, Isoflurane
- Abstract
Objectives: To compare pulmonary gas exchange, tissue oxygenation and cardiovascular effects of four levels of end-expiratory pressure: no positive end-expiratory pressure (ZEEP), positive end-expiratory pressure (PEEP) of maximal respiratory system compliance (PEEPmaxC
rs ), PEEPmaxCrs + 2 cmH2 O (PEEPmaxCrs+2 ), PEEPmaxCrs + 4 cmH2 O (PEEPmaxCrs+4 ), in isoflurane-anesthetized dogs., Study Design: Prospective randomized crossover study., Animals: A total of seven healthy male Beagle dogs, aged 1 year and weighing 10.2 ± 0.7 kg (mean ± standard deviation)., Methods: The dogs were administered acepromazine and anesthesia was induced with propofol and maintained with isoflurane. Ventilation was controlled for 4 hours with ZEEP, PEEPmaxCrs , PEEPmaxCrs+2 or PEEPmaxCrs+4 . Cardiovascular, pulmonary gas exchange and tissue oxygenation data were evaluated at 5, 60, 120, 180 and 240 minutes of ventilation and compared using a mixed-model anova followed by Bonferroni test. p < 0.05 was considered significant., Results: Cardiac index (CI) and mean arterial pressure (MAP) were lower in all PEEP treatments at 5 minutes when compared with ZEEP. CI persisted lower throughout the 4 hours only in PEEPmaxCrs+4 with the lowest CI at 5 minutes (2.15 ± 0.70 versus 3.45 ± 0.94 L minute-1 m-2 ). At 180 and 240 minutes, MAP was lower in PEEPmaxCrs+4 than in PEEPmaxCrs , with the lowest value at 180 minutes (58 ± 7 versus 67 ± 7 mmHg). Oxygen delivery index (DO2 I) was lower in PEEPmaxCrs+4 than in ZEEP at 5, 60, 120 and 180 minutes. Venous admixture was not different among treatments., Conclusion and Clinical Relevance: The use of PEEP caused a transient decrease in MAP and CI in lung-healthy dogs anesthetized with isoflurane, which improved after 60 minutes of ventilation in all levels of PEEP except PEEPmaxCrs+4 . A clinically significant improvement in arterial oxygenation and DO2 I was not observed with PEEPmaxCrs and PEEPmaxCrs+2 in comparison with ZEEP, whereas PEEPmaxCrs+4 decreased DO2 I., (Copyright © 2021 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)- Published
- 2021
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