Objective: To observe the pathological changes in exfoliated cells from lower respiratory tract mucosa in patients undergoing mechanical ventilation for various duration.
Methods: The secretion of lower respiratory tract was collected in 144 patients of cerebral vascular diseases undergoing invasive mechanical ventilation, and exfoliated cells were examined under microscope at different time points. According to specimen collection time they were divided into five groups: less than 8 hours (28 cases), 8-24 hours (46 cases), 24 hours-3 days (22 cases), 3-7 days (20 cases), 7-28 days (14 cases), and over 28 days (14 cases). Then the injury to airway mucosa at different time of mechanical ventilation was determined.
Results: The mucosal injury of trachea and bronchial was worsened gradually with the prolongation of mechanical ventilation. Airway mucosa structure of less than 8-hour of mechanical ventilation was generally normal, while most cells after 8-24 hours and 24 hours-3 days of ventilation showed mild injury, and most cells from tracheal and bronchial mucosa showed severe injury after 3-7 days, 7-28 days and over 28 days of ventilation. Except the difference was not statistically significant between 7-28 days and over 28 days group (P>0.05), the differences between remaining groups were statistically significant (all P<0.05). The correlated coefficient between the duration of mechanical ventilation and airway mucosal injury was 0.781 (P<0.05), and the difference was statistically significant.
Conclusion: There are linear correlation between length of mechanical ventilation and the airway mucosal cell injury; injuries emerges when the mechanical ventilation time exceeds 8 hours with the prolongation mechanical ventilation time, there is severe damage of airway mucosa when mechanical ventilation lasted more than 7 days, but there is no difference in extent of injury after 7 days.