Premium
Effects of end‐inspiratory and end‐expiratory pressures on alveolar recruitment and derecruitment in saline‐washout‐induced lung injury – a computed tomography study
Author(s) -
Luecke T.,
Roth H.,
Joachim A.,
Herrmann P.,
Deventer B.,
Weisser G.,
Pelosi P.,
Quintel M.
Publication year - 2004
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2004.00265.x
Subject(s) - medicine , positive end expiratory pressure , expiration , tidal volume , anesthesia , ventilation (architecture) , lung , saline , mechanical ventilation , lung volumes , respiratory physiology , respiratory system , mechanical engineering , engineering
Background: Lung protective ventilation using low end‐inspiratory pressures and tidal volumes (V T ) has been shown to impair alveolar recruitment and to promote derecruitment in acute lung injury. The aim of the present study was to compare the effects of two different end‐inspiratory pressure levels on alveolar recruitment, alveolar derecruitment and potential overdistention at incremental levels of positive end‐expiratory pressure. Methods: Sixteen adult sheep were randomized to be ventilated with a peak inspiratory pressure of either 35 cm H 2 O (P 35 , low V T ) or 45 cm H 2 O (P 45 , high V T ) after saline washout‐induced lung injury. Positive end‐expiratory pressure (PEEP) was increased in a stepwise manner from zero (ZEEP) to 7, 14 and 21 cm of H 2 O in hourly intervals. Tidal volume, initially set to 12 ml kg −1 , was reduced according to the pressure limits. Computed tomographic scans during end‐expiratory and end‐inspiratory hold were performed along with hemodynamic and respiratory measurements at each level of PEEP. Results: Tidal volumes for the two groups (P 35 /P 45 ) were: 7.7 ± 0.9/11.2 ± 1.3 ml kg −1 (ZEEP), 7.9 ± 2.1/11.3 ± 1.3 ml kg −1 (PEEP 7 cm H 2 O), 8.3 ± 2.5/11.6 ± 1.4 ml kg −1 (PEEP 14 cm H 2 O) and 6.5 ± 1.7/11.0 ± 1.6 ml kg −1 (PEEP 21 cm H 2 O); P < 0.001 for differences between the two groups. Absolute nonaerated lung volumes during end‐expiration and end‐inspiration showed no difference between the two groups for given levels of PEEP, while tidal‐induced changes in nonaerated lung volume (termed cyclic alveolar instability, CAI) were larger in the P 45 group at low levels of PEEP. The decrease in nonaerated lung volume was significant for PEEP 14 and 21 cm H 2 O in both groups compared with ZEEP ( P < 0.005). Overinflated lung volumes, although small, were significantly higher in the P 45 group. Significant respiratory acidosis was noted in the P 35 group despite increases in the respiratory rate. Conclusion: Limiting peak inspiratory pressure and V T does not impair alveolar recruitment or promote derecruitment when using sufficient levels of PEEP.