High PEEP Reduces Recruitment/Derecruitment During Neurally Adjusted Ventilatory Assist in Mild Experimental ARDS
2016 (English)Conference paper (Refereed)
Introduction: Whether spontaneous breathing (SB) should be used in early acute respiratory distress syndrome (ARDS) is questioned. SB may increase the tidal strain/stress and induce tidal recruitment/derecruitment (R/D), leading to ventilation induced lung injury (VILI), by too large or unpredictable tidal volumes (VT). We hypothesized that high levels of positive end-expiratory pressure (PEEP) during SB would prevent derecruitment of tidally recruited lung regions and in that way reduce the R/D phenomena. The aim was to test this hypothesis in a porcine model of mild ARDS during neurally adjusted ventilatory assist (NAVA).
Methods: 5 anesthetized tracheotomized piglets (25-30 kg) were lung lavaged and tracheally suctioned to create a mild ARDS model (PaO 2/FiO2 ratio of 200). The animals were ventilated with NAVA. The NAVA level was titrated to achieve an adequate unloading of the respiratory muscles . PEEP was incremented in steps of 3 cmH2O from 0 to 15 cmH2O and then decremented in a similar way to 0 cmH2 O. At each step paradiaphragmatic dynamic computed tomography scans were acquired. The extension of the atelectatic tissue was defined by the amount of voxels with a Hounsfield unit density between -100 and +100 divided by the total lung area. This was calculated
both at end-expiration (ATexp) and end-inspiration (ATinsp). R/D was calculated as the percentage difference between ATexp and ATinsp.
Results: Tidal R/D decreased from 3,8±0,04% to 1,0±0.0% (mean±SD) when PEEP gradually was changed from 0 to 15 cmH20 and increased again to 3,7±0.03% when PEEP was reduced to baseline (0 cmH20) (p < 0,001). Similarly, the amount of end-expiratory atelectasis decreased from 24,2±9,9% to 4,7±12% when PEEP was increased from 0 to 15 cmH2O.
Conclusion: R/D phenomena exist in spontaneously breathing modes as NAVA and can be mitigated by increasing PEEP. This indicates that PEEP levels higher than the ones normally used in clinical settings could be applied in SB ARDS patients in order to reduce R/D phenomena and the risk of VILI.
Place, publisher, year, edition, pages
, Am J Respir Crit Care Med. 2016;193
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-308408OAI: oai:DiVA.org:uu-308408DiVA: diva2:1049659
International Conference of the American-Thoracic-Society (ATS)