Biphasic Positive Airway Pressure Ventilation In Patients With Acute Lung Injury

Objective:The small tidal ventilation of lung protective strategy is a effective method in treatment of patients with acute lung injury(ALI) and acute respiratory distress syndrome(ARDS),which can significantly decrease the mortality of patients with ALI and ARDS,preventing the possibility of ventilator-induced lung injury(VILI).Volume controlled ventilation with positive end expiratory pressure are conventional mechanical ventilation mode nowadays,however,often giving rise to delayed weaning from mechanical ventilation,breathing muscle weakness as well as deletious effect on hymodynamics,etc.Biphasic positive airway pressure ventilation which is a new style of ventilation mode owing to low airway pressure,less adverse effect on hemodynamics, keeping spontaneous breathing during mechanical ventilation and other benefits,was drawn more and more attention by medical members and applied in patients with ALI and ARDS.So,which approaches are the better one to treatment ALI with less adverse effect is the major objective of our study.Methods:20 patients with ALI received treatment of mechanical ventilation were randomized into volume controlled ventilation group(group A) and biphasic positive airway pressure ventilation group(group B).There were 10 patients in group A and 10 patients in group B.The patients in group A were paralyzed with sufficient sedatives,the tidal volume were set at 6-8ml/kg,the inspiratory to expiratory time ratio was set at 1∶1-1.5,positive end expiratory pressure(PEEP) was set between 5cmH₂O and 10cmH₂O,the fraction of inspiratory oxygen(FiO₂)was adjusted to the value that arterial partial pressure of oxygen above 60mmHg,the ventilator rate were adjusted to the value that arterial partial pressure of carbon dioxide maintained the value between 40 mmHg and 80 mmHg;The patients in group B were maintained spontaneous breathing,the high pressure level(P_high) were set at blow 35mmHg,the low pressure level (P_low) were set the value between 5cmH₂O and 10cmH₂O,the ratio of duration of high pressure level to the duration of low pressure level were 1∶1-1.5,the difference between high pressure level and lower pressure level was adjusted to the value that produced the tide of 6-8ml/kg,the methods of setting RR and FiO₂ were similar to the group A.We compared the oxygenation index(OI),arterial partial pressure of oxygen(PaO₂),arterial partial pressure of carbon dioxide(PaCO₂),the value of PH,arterial oxygen saturatioin(SaO₂),peak airway pressure(PIP),the compliance of dynamic respiratory system(C_RS,dyn),mean pulmonary arterial pressure(MPAP),heart rate(HR),between the tow groups,at 4hr,8 hr,12hr,24hr,36hr,48hr,during the initial 48h observation period,as well as the dosage of sedative and duration of ventilation ultimatedly.Results:After ventilation,arterial partial pressure of oxygen(PaO)2,arterial oxygen saturatioin(SaO2), oxygenation index(OI)in tow groups increased significantly(P＜0.05),compared with those ALI,which showed increased trend,between the tow groups,the increased amplitude of group B is greater and were greatly higher than those of group A at 36hr and 48hr(P＜0.001);arterial partial pressure of carbon dioxide(PaCO2)increased markedly,in comparison with that of ALI,of the tow groups,although which increased obviously,without significant difference between the tow groups;On the country,pH declined ha tow groups,which decreased more greatly in group A at 24 h,36 h and 48 h than those of group B respectively;peak airway pressure(PIP) in group A were higher than that of group B;mean arterial pressure(MAP) in both group A and group B during ALI were lower than those of mechanical ventilation(P＜0.001),which was significantly higher in group B than that of group A at 48h;CRS,sta in group B was higher than that of group A,however,there was no significantly difference between the goups;At the end of ventilation,the dosage of sedation and duration of intubation in group A were greatly than those of group B(P＜0.05).Conclusions:1.Biphasic positive airway pressure ventilation can be more effective to improve the patient's oxygenation with less adverse effects on hemodynamics than volume controlled ventilation.2.Biphasic positive airway pressure ventilation need less consumption of sedative and duration of intubation than volume controlled ventilation,which can avoiding the delay of weaning due to the administration of sedative and muscle relaxant...