The Effect of Bi-level Ventilation Mode on Blood Gas and Hemodynamics of Patients with Acute Lung Injury

Objective To investigate the effect of bi-level ventilation mode on blood gas and hemodynamics of patients with acute lung injury (ALI) by pulse indicator continuous cardiac output(PiCCO),and the clinical effect of this new ventilation mode on patients with ALI as well as its influence degree of circulatory system so that the cure rate of ALI can be improved. Methods There were 42 patients with ALI,27 male and 15 female aged 15-75 years. According to the order of hospitalization,40 patients (2 patients did not complete the study) were divided into two groups with 20 patients in each group. Bi-level ventilation group included the first 20 admitted patients. They were given bi-level ventilation support,using Support/Time(S/T) mode. The initial set of end inspiratory pressure (IPAP) was 8-10 cm H2O gradually increased to 14-20 cm H2O,which should be comfortable and appropriate for patients. The initial set of end expiratory pressure (EPAP) was 3-5 cm H2O gradually increased to 8-12 cm H2O. Fraction of inspired oxygen(FiO2) unchanged. Control group included the rest 20 admitted patients. They were given respiratory support,using Auxiliary/Control(A/C) mode followed by an increased positive end-expiratory pressure (PEEP) of 5 cm H2O,10 cm H2O,15 cm H2O,20 cm H2O. Each pressure kept 30 min. FiO2 unchanged. Indexes such as cardiac output (CO),systemic vascular resistance (SVR) etc were observed in both groups. Results There were 13 deaths in two groups,including 5 in bi-level ventilation group and 8 in control group. Seven cases died of multiple organ failure,3 died of septic shock and 3 died of circulatory failure. Endotracheal intubation time (2.9±0.8 d vs. 4.2±0.9 d,t=7.737,P=0.006) and hospital stay (17.2±4.5 d vs. 18.5±3.6 d,t=2.558,P=0.039) in bi-level ventilation group were significantly shorter than those in control group. In control group,when PEEP ranged from 5 cm H2O to 15 cm H2O,arterial partial pressure of oxygen (PaO2) and oxygenation index (PaO2/FiO2) gradually increased as PEEP increased (P0.05); when PEEP increased to 20 cm H2O,CO decreased,SVR,pulmonary vascular resistance (PVR) and airway peak pressure (PIP) increased than those in range of 5-15 cm H2O (P0.05). In bi-level ventilation group,PaO2 and PaO2/FiO2 gradually increased as EPAP increased. When EPAP increased to 10 cm H2O,PaO2 and PaO2/FiO2 increased to the maximum (P0.05); PIP was significantly lower than that in control group (t=7.831,P=0.000). Conclusion Giving bi-level ventilation treatment to patients with ALI/acute respiratory distress syndrome(ARDS) can reduce the effects on respiratory and hemodynamic. PIP and the time of endotracheal intubation and hospital stay can be reduced without affecting hemodynamics.