The Comparison Of Pressure Controlled Ventilation Versus Volume Controlled Ventilation On Ventilator Induced Lung Injury

ObjectivePressure controlled ventilation ( PCV) and Volume controlled ventilation (VCV) both were the measure for the patients with respiratory failure at the present time. The potential clinical benefits of PCV over VCV in patients with Respiratory Failure still remain debated. To explore The potential clinical benefits, We compared PCV with VCV in patients with respiratory failure with respect to the following points;respiratory mechanics , TNF - a and SP - A.MethodsFrom June 2004 to April 2005, we enrolled 20 patients (13 men and 7 woman;age range, 20 to 75 years. ) with Respiratory Failure which needed be ventilated at emergency ICU of the first affiliated hospital of China Medical University . Patients were randomly assigned to Group A and B . Group A were first ventilated in PCV for 12 hours ,and then in VCV for 12 hours . Group B were first ventilated in VCV, and then in VCV. Sequential ventilation in PCV and VCV with a constant inspiratory / expiratory ratio (1:2—3), tidal volume (6 -8ml/kg) ,respiratory rate (15 - 26) ,and total positive end expiratory pressure (2 - 12cmH₂O) ,FiO₂(40% -60% ) . measurement of gas exchange and compliance and airway peak inspiratory pressures;and serum concentration of surfactant protein A and TNF - α;arterial blood gas and hemodynamics ( blood pressure and heart rate) .Statistical Analysis;Quantitative variables were given as x ±s. Group comparisons were made using analysis of variance. The correlation analysis betweenfactors was used by Pearson analysis method. There was statistical difference when P value of < 0.05.ResultsHemodynamics ( blood pressure and heart rate) did not differ between PCV and VCV. The PaO2/fractk>n of inspired oxygen ratio levels (235. 8 ± 31. 39mmHg)in PCV was better than that in VCV(199.2 ±24.91 mmHg ) , but it has no statistics significance (P>0.05). Peak inspiratory pressure was significantly lower in PCV compared with VCV (27. 9 ± 1. 35cmH2O vs 33. 8 ± 1. 48cmH2O,P <0.05). Compliance in PCV was better than in VCV (0. 062 ±0. 002 cmH20 /ml vs 0. 042 ±0.002cmH2O/ml, P <0.05). The serum concentration of surfactant protein A and TNF - a were lower in PCV compared with VCV (25.25 ±0.965 vs 36. 5 ±0. 822,0. 546 ±0.063 vs 0.994 ±0. 157|xg/ml,respectively ) . Lower PIP was associated with lower concentration of surfactant protein A and TNF - a(r =0. 386,r =0. 404, respectively) , and associated with better compliance(r = — 0.48) . Serum concentration of surfactant protein A inverse correlated Pa02/fraction of inspired oxygen ratio levels (r = -0. 393 ,P < 0. 05 ) and compliance( r = - 0.407 , P < 0. 05 ) .ConclusionsThese data show that PCV allows the generation of lower PIP and SP - A and TNF - a. PCV can better avoid the ventilator induced lung injury. PIP is an important fact of ventilator induced lung injury, serum concentration of surfactant protein A could be a tool toestimate VILI.