Lung hyperinflation stimulates the release of inflammatory mediators in spontaneously breathing subjects.

Lung hyperinflation up to vital capacity is used to re-expand collapsed lung areas and to improve gas exchange during general anesthesia. However, it may induce inflammation in normal lungs. The objective of this study was to evaluate the effects of a lung hyperinflation maneuver (LHM) on plasma cytokine release in 10 healthy subjects (age: 26.1 +/- 1.2 years, BMI: 23.8 +/- 3.6 kg/m(2)). LHM was performed applying continuous positive airway pressure (CPAP) with a face mask, increased by 3-cmH(2)O steps up to 20 cmH(2)O every 5 breaths. At CPAP 20 cmH(2)O, an inspiratory pressure of 20 cmH(2)O above CPAP was applied, reaching an airway pressure of 40 cmH(2)O for 10 breaths. CPAP was then decreased stepwise. Blood samples were collected before and 2 and 12 h after LHM. TNF-alpha, IL-1beta, IL-6, IL-8, IL-10, and IL-12 were measured by flow cytometry. Lung hyperinflation significantly increased (P < 0.05) all measured cytokines (TNF-alpha: 1.2 +/- 3.8 vs 6.4 +/- 8.6 pg/mL; IL-1beta: 4.9 +/- 15.6 vs 22.4 +/- 28.4 pg/mL; IL-6: 1.4 +/- 3.3 vs 6.5 +/- 5.6 pg/mL; IL-8: 13.2 +/- 8.8 vs 33.4 +/- 26.4 pg/mL; IL-10: 3.3 +/- 3.3 vs 7.7 +/- 6.5 pg/mL, and IL-12: 3.1 +/- 7.9 vs 9 +/- 11.4 pg/mL), which returned to basal levels 12 h later. A significant correlation was found between changes in pro- (IL-6) and anti-inflammatory (IL-10) cytokines (r = 0.89, P = 0.004). LHM-induced lung stretching was associated with an early inflammatory response in healthy spontaneously breathing subjects.