LOWER THAN SIX MILLILITER / KILOGRAM ENHANCES LUNG PROTECTION : ROLE OF EXTRACORPOREAL CARBON DIOXIDE REMOVAL

Background: Tidal hyperinflation may occur in patients with acute respiratory distress syndrome that ventilated with a tidal volume (VT) of 6 ml/kg of predicted body weight develop a plateau pressure (PPLAT) of 28≤PPLAT≤30 cmH2O. We verified if VT<6 ml/kg may enhance lung protection and that consequent respiratory acidosis may be managed by extracorporeal carbon dioxide removal. Methods: PPLAT, lung morphology computed tomography, and pulmonary inflammatory cytokines (broncho-alveolar lavage) were assessed in 32 patients ventilated with a VT of 6 ml/kg. Data are provided as mean ± standard deviation or median and interquartile (25 and 75 percentile) range. In patients with 28≤PPLAT≤30 cmH2O (N=10), VT was reduced from 6.3±0.2 to 4.2±0.3 ml/kg and PPLAT decreased from 29.1±1.2 to 25.0±1.2 cmH2O (P<0.001); consequent respiratory acidosis (PaCO2 from 48.4±8.7 to 73.6±11.1 mmHg and pH from 7.36±0.03 to 7.20±0.02; P<0.001) was managed by extracorporeal carbon dioxide removal. Lung function, morphology and pulmonary inflammatory cytokines were also assessed after 72 hours. Results: Extracorporeal assist normalized PaCO2 (50.4±8.2 mmHg) and pH (7.32±0.03) and allowed use of VT lower than 6 ml/Kg for 144 [84,168] hours. The improvement of morphological markers of lung protection and the reduction of pulmonary cytokines concentration (P<0.01) were observed after 72 hours of ventilation with VT lower than 6 ml/Kg. No “patient related” complications were observed. RANIERI #ALN200903004 REVISED III 5 Conclusions: VT lower than 6 ml/Kg enhanced lung protection. Respiratory acidosis consequent to low VT ventilation was safely and efficiently managed by extracorporeal carbon dioxide removal. RANIERI #ALN200903004 REVISED III 6