Effect of high frequency oscillatory ventilation on EVLW and lung capillary permeability of piglets with acute respiratory distress syndrome caused by pulmonary and extrapulmonary insults.

The effect of high frequency oscillatory ventilation (HFOV) at early stage on hemodynamic parameters, extravascular lung water (EVLW), lung capillary permeability, CC16 and sICAM-1 in piglets with pulmonary or extrapulmonary acute respiratory distress syndrome (ARDS) was explored. Central vein pressure (CVP) and pulse indicator continuous cardiac output (PiCCO) were monitored in 12 anesthetized and intubated healthy piglets. Pulmonary ARDS (ARDSp) and extrapulmonary ARDS (ARDSexp) models were respectively established by lung lavage of saline solution and intravenous injection of oleic acid. Then the piglets received HFOV for 4 h. EVLW index (EVLWI), EVLW/intratroracic blood volume (ITBV) and pulmonary vascular permeability index (PVPI) were measured before and after modeling (T0 and T1), and T2 (1 h), T3 (2 h), T4 (3 h) and T5 (4 h) after HFOV. CC16 and sICAM-1 were also detected at T1 and T5. Results showed at T1, T3, T4 and T5, EVLWI was increased more significantly in ARDSp group than in ARDSexp group (P<0.05). The EVLWI in ARDSp group was increased at T1 (P=0.008), and sustained continuously within 2 h (P=0.679, P=0.216), but decreased at T4 (P=0.007) and T5 (P=0.037). The EVLWI in ARDSexp group was also increased at T1 (P=0.003), but significantly decreased at T3 (P=0.002) and T4 (P=0.019). PVPI was increased after modeling in both two groups (P=0.004, P=0.012), but there was no significant change within 4 h (T5) under HFOV in ARDSp group, while PVPI showed the increasing trends at first, then decreased in ARDSexp group after HFOV. The changes of EVLW/ITBV were similar to those of PVPI. No significant differences were found in ΔEVLWI (P=0.13), ΔPVPI (P=0.28) and ΔEVLW/ITBV between the two groups (P=0.63). The significant decreases in both CC16 and sICAM-1 were found in both two groups 4 h after HFOV, but there was no significant difference between the two groups. It was concluded that EVLWI and lung capillary permeability were markedly increased in ARDSp and ARDSexp groups. EVLW could be decreased 4 h after the HFOV treatment. HFOV, EVLW/ITBV and PVPI were increased slightly at first, and then decreased in ARDSexp group, while in ARDSp group no significant difference was found after modeling. No significant differences were found in the decreases in EVLW and lung capillary permeability 4 h after HFOV.