Effects And Mechanism Of Heliox Ventilation On Patients With Acute Lung Injury

Objective: Explore the effect and mechanism of heliox ventilation on the treatment of patients with acute lung injury(ALI), by measuring the Respiratory mechanics index, Blood gas analysis and the serum levels of matrix metallo proteinases 9(MMP-9), transforming growth factor beta1(TGF-β1) and tumor necrosis factor alpha(TNF-α) in patients who had been on heliox mechanic ventilation.Methods: There were 30 patients with ALI include 12 male and 18 female. They had been studied with an average age of 51.60±8.08. Their mean weight was 55.65±10.31 Kg. All the patients were randomly divided into two groups, with 15 cases for each group. The patients were treated by volume control ventilation with a modified ventilator. The respiratory parameters follows: Tidal volume 8ml/kg, respiratory rate 15±5.00 times/min, positive end-expiratory pressure 6cm H2 O and inhale exhale ratio 1:1.5. In group A, the patients were breathed with pure oxygen for 5min to drive out the nitrogen, and then replaced by helium-oxygen mixture gas(heliox) to mechanical ventilation(60% helium, 40% oxygen, Fi O2: 40%). In group B: the patients were same to group A first and then replaced by air-oxygen mixture gas to mechanical ventilation(60% air, 40% oxygen, Fi O2: 40%). At the time point of before mechanical ventilation(T0), after mechanical ventilation 30min(T1), 60min(T2) and 120min(T3), the parameters of hemodynamic and respiratory mechanics of the patients were recorded. At the same time, carotid artery blood was extracted to detect the serum levels of MMP-9, TGF-β1 and TNF-α by ELISA and blood-gas analysis.Results: There was no obvious difference at peripheral oxygen saturation, heart rate, blood pressure, mean arterial pressure between two groups before treatment(P>0.05). After heliox mechanical ventilation for 120 minutes, the patients with ALI in group A had an apparent decline in peak airway pressure, airway plateau pressure, and Pa CO2 with differences statistically significant(P<0.05), while there was a significant rise in their Pa O2(P<0.05). Compared with group B, the serum levels of MMP-9, TGF-β1 and TNF-α decreased after heliox mechanical ventilation in group A. But compared with the T2 and T3 point, the serum levels of TGF-β1 in group A has no changes at T1 point(P<0.05). In group A, the serum levels of MMP-9 had started to decline at the T2 point and TNF-α had dropped at the T0 point, this two indicators were minimized at T3 point(P <0.05). There was an upward trend in the serum levels of TGF-β1, TNF-α in group B after air-oxygen mechanical ventilation(P <0.05). But there was no changes in MMP-9 compared with before treatment in group B(P >0.05).Conclusion:1、The hemodynamics parameters of patients with ALI are stable state after heliox mechanical ventilation 120 min. It proves that the security of this breathing pattern. 2、Compared with traditional air-mixed oxygen ventilation, heliox ventilation has significant advantages over improving the patients’ parameters of pulmonary mechanics and oxygenation status. 3、After heliox ventilation for 120 minutes, the serum level of MMP-9, TGF-β1 and TNF-α in patients with ALI have an obvious fall, which might inhibit the inflammatory response of patients. According to changes of serum TGF-β1、MMP-9,it provide a good hint that heliox ventilation could inhibit the progression of pulmonary fibrosis at the very start and the treatment need for continuous.