Effect of hyperventilation and starvation on rat lung mechanics and surfactant

We studied the effects of hyperventilation and starvation on rat lung mechanics and surfactant. We hyperventilated lungs by excising and ventilating them at 3 times the normal tidal volume. Three days starvation reduced the alveolar pool of disaturated phosphatidyl choline by about 20% but did not significantly reduce the functional residual capacity. Air and saline deflation pressure-volume curves were performed in 4 groups: control lungs, lungs from starved rats, hyperventilated lungs, and hyperventilated lungs from starved rats. The area under each curve was calculated; this indicated the relative position of the curve in the pressure-volume diagram. We found that starvation did not change recoil, that hyperventilation increased surface recoil, and that combined starvation and hyperventilation increased it even more. We conclude that hyperventilation-induced dysfunction of surfactant is greater when the alveolar pool of surfactant is reduced by starvation. This effect might also occur clinically in the intensive care setting.