Ventilação mecânica associada à manobra de recrutamento alveolar e peep de manutenção no transoperatório não previne hipoxemia na recuperação pós-anestésica em equinos

This study assesses whether maintaining intraoperative PEEP of 7, 12 or 17 cmH2O after alveolar recruitment maneuver (ARM) is able to prevent hypoxemia (PaO2/FiO2 <285) during the post-anesthetic recovery (PAR) of healthy equines. Seventeen horses after fasting for 12 hours were anesthetized with isoflurane, positioned supine for arthroscopic surgery and received IPPV with Vt of 14 mL/kg and FiO2 of 0.7. After ARM, the animals were kept randomly with PEEP of 7 (7PEEP, n = 6), 12 (12PEEP, n = 6) or 17 cmH2O (17PEEP, n = 5) for 120 minutes (end of anesthesia). After measuring SaO2 and PaO2 (basal), the animals were weaned with support pressure and the data were measured again at 10, 20 and 30 minutes after weaning (PD10, PD20, PD30). For statistical analysis ANOVA and Tukey test were performed. It was observed a significant decrease in SaO2 (%) in PD10, PD20 and PD30 in horses of the groups: 7PEEP (86.8 ± 7.2, 85.0 ± 10.3, 87.3 ± 7.4), 12PEEP (86.2 ± 6.3, 86.1 ± 5.7, 85.7 ± 4.3) and 17PEEP (89.8 ± 2.5, 89.2 ± 3.7, 91.2 ± 2.8) compared to baseline (7PEEP 99.1 ± 1.6; 12PEEP 99.8 ± 0.4; 17PEEP 99.8 ± 0.4, p <0.05). There was a significant decrease in the PaO2/FiO2 ratio during PAR (PD10, PD20 and PD30) in horses of the groups: 12PEEP (235.7 ± 40.7, 232.5 ± 42.5, 224.6 ± 34.6) and 17PEEP (261.9 ± 37.2, 255.8 ± 38.2, 274.7 ± 30.2) compared to baseline (12PEEP 339.9 ± 44.8; 17PEEP 385.2 ± 99.1, p <0.05), while observing hypoxemia during PAR. There was no significant difference in SaO2 and PaO2/FiO2 between groups. The maintenance of intraoperative PEEP at 7, 12 and 17 cmH2O after ARM was unable to prevent hypoxemia in PAR of healthy horses.