Alveolar Tidal recruitment/derecruitment and Overdistension During Four Levels of End-Expiratory Pressure with Protective Tidal Volume During Anesthesia in a Murine Lung-Healthy Model

Soares, José Agnelo; Carvalho, Alysson R.; Bergamini, Bruno Curty; Gress, M. A. K. A.; Jandre, Frederico C.; Zin, Walter A.; Giannella-Neto, Antonio

doi:10.1007/s00408-018-0096-8

Cited by 6 publications

(3 citation statements)

References 43 publications

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“…Nevertheless, the improvement in PaO 2 /FIO 2 observed in all studied PEEP levels when compared to ZEEP are considered small, with minimal clinical significance since PaO 2 /FIO 2 remained within normal limits with all treatments. The improvement in PaO 2 /FIO 2 caused by PEEP was more important toward the end of the ventilation protocol and was likely caused by a faster temporal development of atelectasis and deterioration of respiratory mechanics in the cats ventilated with ZEEP compared to PEEP as previously demonstrated in dogs ( 3 ) and rats ( 11 ). When excessive, PEEP can cause alveolar overdistention and decrease pulmonary perfusion, which can ultimately impair pulmonary gas exchange as a consequence of increased

(alveolar dead space) ( 13 ).…”

Section: Discussionsupporting

confidence: 55%

“…One of the first methods described to individualize PEEP used the PEEP maxCrs achieved during a decremental PEEP titration, which was associated with optimal cardiopulmonary function in critical human patients ( 25 ). In addition, PEEP maxCrs promoted a better balance between preventing alveolar tidal recruitment/derecruitment and overdistention when compared to higher PEEP or ZEEP in lung-healthy rats ( 11 ). This beneficial effect of PEEP maxCrs may explain why this level of PEEP was associated with improved clinical outcomes in critical human patients ( 10 ).…”

Section: Discussionmentioning

confidence: 99%

“…The PEEP of maximal respiratory system compliance (PEEP maxCrs ) achieved during a decremental PEEP titration has been recently used as a method to individualize PEEP in protocols of protective ventilation ( 9 , 10 ). In healthy rats, PEEP maxCrs promoted a better balance between alveolar overdistention and tidal recruitment/derecruitment when compared to higher PEEP or the absence of it ( 11 ). In addition, PEEP levels higher than PEEP maxCrs seems to provide better prevention of atelectasis but at the expense of causing alveolar overdistension ( 11 , 12 ) impairing cardiovascular function ( 5 ), and possibly causing redistribution of pulmonary blood with an increase in ventilation/perfusion (

) mismatch ( 13 ).…”

Section: Introductionmentioning

confidence: 99%

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Cardiovascular and Gas Exchange Effects of Individualized Positive End-Expiratory Pressures in Cats Anesthetized With Isoflurane

et al. 2022

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ObjectivesTo compare the effects of four levels of end-expiratory pressure [zero (ZEEP) and three levels of positive end-expiratory pressure (PEEP)] on the cardiovascular system and gas exchange of cats anesthetized with isoflurane and mechanically ventilated for 3 h with a tidal volume of 10 ml/kg.Study DesignProspective, randomized, controlled trial.AnimalsSix healthy male neutered purpose-bred cats.MethodsAnesthesia was induced with isoflurane and maintained at 1.3 minimum alveolar concentration. PEEP of maximal respiratory compliance (PEEPmaxCrs) was identified in a decremental PEEP titration, and cats were randomly ventilated for 3 h with one of the following end-expiratory pressures: ZEEP, PEEPmaxCrs minus 2 cmH2O (PEEPmaxCrs−2), PEEPmaxCrs, and PEEPmaxCrs plus 2 cmH2O (PEEPmaxCrs+2). Cardiovascular and gas exchange variables were recorded at 5, 30, 60, 120, and 180 min (T5 to T180, respectively) of ventilation and compared between and within ventilation treatments with mixed-model ANOVA followed by Dunnet's and Tukey's tests (normal distribution) or Friedman test followed by the Dunn's test (non-normal distribution). Significance to reject the null hypothesis was considered p < 0.05.ResultsMean arterial pressure (MAP—mmHg) was lower in PEEPmaxCrs+2 [63 (49–69); median (range)] when compared to ZEEP [71 (67–113)] at T5 and stroke index (ml/beat/kg) was lower in PEEPmaxCrs+2 (0.70 ± 0.20; mean ± SD) than in ZEEP (0.90 ± 0.20) at T60. Cardiac index, oxygen delivery index (DO2I), systemic vascular resistance index, and shunt fraction were not significantly different between treatments. The ratio between arterial partial pressure and inspired concentration of oxygen (PaO2/FIO2) was lower in ZEEP than in the PEEP treatments at various time points. At T180, DO2I was higher when compared to T5 in PEEPmaxCrs. Dopamine was required to maintain MAP higher than 60 mmHg in one cat during PEEPmaxCrs and in three cats during PEEPmaxCrs+2.ConclusionIn cats anesthetized with isoflurane and mechanically ventilated for 3 h, all levels of PEEP mildly improved gas exchange with no significant difference in DO2I when compared to ZEEP. The PEEP levels higher than PEEPmaxCrs−2 caused more cardiovascular depression, and dopamine was an effective treatment. A temporal increase in DO2I was observed in the cats ventilated with PEEPmaxCrs. The effects of these levels of PEEP on respiratory mechanics, ventilation-induced lung injury, as well as in obese and critically ill cats deserve future investigation for a better understanding of the clinical use of PEEP in this species.

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(alveolar dead space) ( 13 ).…”

Section: Discussionsupporting

confidence: 55%