ABSTRACT
Objective To evaluate the effect of high-frequency oscillatory ventilation (HFOV) on lung injury in the piglets with acute respiratory distress syndrome (ARDS).Methods Twelve male piglets,aged 6-8 weeks,weighing 14-16 kg,were randomly divided into 2 groups (n=6 each) using a random number table:conventional mechanical ventilation with low tidal volume group (CMV group) and HFOV group.ARDS was induced by bilateral pulmonary lavages with isotonic saline (38 ℃),repeated every 10 min until the oxygenation index＜200 mmHg.After successful establishment of the model,CMV group was ventilated using conventional mechanical ventilation with low tidal volumes.After successful establishment of the model,HFOV group was ventilated using HFOV,lung recruitment was performed,the airway pressure was set at 25 cmH2O and maintained at this level for 30 s,and the airway pressure was then adjusted 5 cmH2O higher than that after successful establishment of the model,with bias flow 25 L/min,inspiratory time ratio 33％,frequency 8 Hz,amplitude 40-80 cmH2O,and inspiratory oxygen fraction 1.0.In both groups,carbon dioxide partial pressure was maintained between 35 and 50 mmHg.Before establishment of the model (baseline),after successful establishment of the model (T1),and at 0.5,1.0,2.0 and 4.0 h after beginning of mechanical ventilation (T2-5),blood samples were collected from the femoral artery and central vein for blood gas analysis,arterial oxygen partial pressure and carbon dioxide partial pressure were recorded,oxygen delivery index,oxygen consumption index,oxygenation index and intrapulmonary shunt were calculated,and the improvement in pulmonary function (oxygenation index ≥ 200 mmHg) was recorded.At T0,T1 and T5,venous blood samples were collected for determination of the concentrations of serum Clara cell secretory protein 16,soluble intercellular adhesion molecule-1,and high-mobility group box 1.Results Compared with CMV group,the arterial oxygen partial pressure at T35 and oxygenation index at T4.5 were significantly increased (P ＜ 0.05),and no significant change was found in the other parameters in HFOV group (P＞0.05).Conclusion Compared with conventional mechanical ventilation with low tidal volumes,although HFOV improves lung oxygenation,the degree is small in the piglets with ARDS.
ABSTRACT
Objective To evaluate the effects of different types of acute respiratory distress syndrome (ARDS) on high frequency oscillatory ventilation (HFOV)-improved extravascular lung water and pulmonary vascular permeability in piglets.Methods Twelve healthy piglets,weighing 15-20 kg,were randomly allocated into 2 groups (n =6 each) using a random number table:endogenous ARDS (P group) and exogenous ARDS (EXP group).Anesthesia was induced with midazolam and propofol.The tracheal tube was inserted.Anesthesia was maintained with iv infusion of propofol and fentanyl.ARDS was induced with normal saline infused via the tracheal tube in group P.ARDS was induced with oleic acid 0.05 ml/kg injected intravenously over 45-60 min in group EXP.Then 4 h of HFOV was performed.Before ARDS (T0),immediately after ARDS (Ti) and at 1,2,3 and 4 h of HFOV (T2-5),arterial blood samples were collected for blood gas analysis and the variables such as extravascular lung water index (EVLWI),pulmonary vascular permeability index (PVPI),and extravascular lung water (EVLW)/intra thoracic blood volume (ITBV) were monitored.The oxygenation index (PaO2/FiO2) was calculated.Results Compared with the baseline value at T0,the oxygenation index was decreased at T1,and the oxygenation index was less than 200 mm Hg in the two groups (P ＜ 0.05).There was no significant difference in the maximum degree of changes in EVLWI,PVPI and EVLW/ITBV between the two groups (P ＞ 0.05).Conclusion Endogenous and exogenous ARDS disease factor does not affect HFOV-improved extravascular lung water and pulmonary vascular permeability in piglets.