OBJECTIVETo detect the levels of dipalmitoyl phosphatidyl choline (DPPC) in the sputum of the patients with acute cerebral injury without primary pulmonary injury after mechanical ventilation treatment.

METHODSDPPC levels in sputum of 35 patients with acute cerebral injury but without pulmonary injury were detected with high performance liquid chromatography at the beginning of ventilation and 16-20 days, 21-40 days, and 41-60 days after ventilation, respectively.

RESULTSThere was no significant difference of the DPPC levels between 16-20 days after ventilation (3.36+/-0.49) and at the beginning of ventilation (3.37+/-0.58) (P>0.05). The mean levels of DPPC decreased significantly at 21-40 days (2.87 mg/ml+/-0.26 mg/ml, P<0.05) and 41-60 days (1.93 mg/ml+/-0.21 mg/ml, P<0.01) after ventilation compared with that at the beginning of ventilation. At the same period, the peak inspiratory pressure and the mean pressure of airway increased significantly, whereas the static compliance and the partial pressure of oxygen in artery decreased significantly. Among the 25 patients who received ventilation for more than 20 days, 8 (32%) had slightly-decreased partial pressure of oxygen in artery compared with that at the beginning of ventilation.

CONCLUSIONSMechanical ventilation can decrease the DPPC levels, decrease the lung compliance and increase the airway pressure, even impair the oxygenation function in patients with acute cerebral injury. Abnormal DPPC is one of the major causes of ventilator-associated lung injury.