OBJECTIVETo investigate the effect of continuous veno-venous hemodiafiltration (CVVHDF) on endotoxin-induced acute lung injury (ALI) of piglets.

METHODSEighteen piglets were randomly divided into three groups: control group (n = 6); heparin group (n = 6) and CVVHDF treatment group (n = 6). All the animals were anesthetized by muscle injection of ketamine (30 mg/kg), then placed in supine position, received continuous intravenous infusion of ketamine with the rate of 10 mg/(kgxh). After placing a 4.5 cm (inner diameter) tracheal tube via tracheostoma, controlled mechanical ventilation was established using the assisted-controlled ventilation option of the NEWPORT 200. Respiratory rate at 30 breath/min; PIP at 10 cm H2O (1 cm H2O = 0.098 kPa); PEEP at 2 cm H2O and fraction of inspired oxygen at 0.3. A vein catheter was placed into right vena jugularis interna to administer a Ringer's solution. Initially, at a rate of 10 ml/kg, followed by a rate of 15 ml/kg when the mean arterial blood pressure was below 70 mm Hg (1 mm Hg = 0.133 kPa), the rate of 20 ml/kg was used when the mean arterial blood pressure was below 60 mm Hg. An 8Fr double-lumen catheter was inserted into left femoral vein and served as the pathway for CVVHDF. A Pulsiocath Pcco catheter was positioned into left femoral artery to monitor the circulatory parameters. All catheters were flushed with heparinized saline to prevent clotting. Then all the animals were given intravenous infusion of 150 microg/kg endotoxin within 30 minutes to induce ALI. When the oxygenation index < 300 and pulmonary compliance < 30% of the baseline, the animals of heparin group received heparin infusion to maintain blood active coagulation time (ACT) 180 - 250 s, the animals of treatment group received CVVHDF with the blood flow of 50 ml/min, replacement rate of 300 ml/h, dialysis rate of 600 ml/h and the ultrafiltrate rate of 350 ml/h for six hours, heparin infusion to keep blood ACT 180 - 250 s. The circulatory parameters: heart rate (HR), mean arterial blood pressure (MABP), central venous pressure (CVP), pulse contour cardiac output index (PCCI); systemic venous resistance index (SVRI), cardiac function index (CFI), external venous lung water index (EVLWI), left ventricular contractile index (dPmx); respiratory parameters: respiratory rate (RR), pulmonary compliance (Cdyn) were monitored; arterial blood gas analysis was performed and oxygenation index (PaO2/FiO2) was calculated. All the parameters were recorded at baseline (B), onset of ALI (A 0 h), two hours (A 2 h), four hours (A 4 h), six hours (A 6 h) after ALI.

RESULTSNo significant difference in circulatory parameters, respiratory parameters and blood gas analysis were found at B and A 0 h among the three groups. When the ALI occurred, PaO2/FiO2, Cdyn, MABP and PCCI of the three groups decreased; HR, RR, EVLWI, SVRI increased. After four hours of ALI, the RR, EVLWI, SVRI, CFI and dPmx of treatment group were improved, the differences were significant compared with the other two groups (P < 0.05). After six hours of ALI, the HR, PCCI, MABP, PaO2/FiO2 and Cdyn of treatment group were significantly improved, compared with control group and heparin group (P < 0.05). There were no significant differences in any of the parameters between control group and heparin group. The difference in CVP among three groups was not significant.

CONCLUSIONCVVHDF has a good effect on hemodynamics of the endotoxin-induced ALI of the piglets.