[Effects of ventilation and surfactant perturbation on alveolocapillary permeability]

To investigate the effects of large tidal volume ventilation (LTVV) and surfactant dysfunction induced with dioctyl sodium sulphoccinate (DOSS) on alveolocapillary permeability, and on the surface tension of lung tissue extract (LTE).

The permeability index of tecthnetium-99m labelled human serum albumin (99mTc-HSA) was used to characterize the alveolocapillary permeability after LTVV and surfactant dysfunction permeability index, dynamic respiratory compliance (Cdyn), arterial blood gas (ABG), wet lung weight and surface tension of LTE were measured in four groups of rabbits: (1) controls; (2) LTVV; (3) DOSS; and (4) DOSS + LTVV.

Cdyn and ABG were stable throughout the experiment in all groups. The wet lung weight was (1.85 +/- 0.16) g/kg, (2.50 +/- 0.27) g/kg, (1.88 +/- 0.12) g/kg and (2.65 +/- 0.13) g/kg in four groups respectively. It was significantly increased in LTVV and DOSS + LTVV groups compared with controls and DOSS (P < 0.01). The permeability index was 0.10 +/- 0.04, 0.72 +/- 0.14, 0.13 +/- 0.03 and 0.79 +/- 0.17 in four groups respectively. There was a significantly increased permeability index in LTVV and DOSS + LTVV groups compared with controls and DOSS (P < 0.01). There was no difference of surface tension of LTE among all groups.

The results of this study suggest that the increased alveolocapillary permeability, pulmonary edema and lung injury are induced by LTVV rather than DOSS. The mechanisms of HSA transferring alveolocapillary membrane from different directions are different.