Role of spontaneous ventilation in diaphragm protection during invasive mechanical ventilation in patients with acute respiratory distress syndrome: a prospective observational study.

OBJECTIVE

To evaluate the effect of spontaneous ventilation duration during invasive mechanical ventilation on diaphragm protection, defined as maintaining a diaphragm thickness fraction between 15% and 30%.

METHODS

The present prospective, observational study enrolled one hundred adult patients with mild to moderate acute respiratory distress syndrome requiring invasive mechanical ventilation. After recruitment, the mode of invasive mechanical ventilation was recorded, and the diaphragm thickness fraction was measured daily until patients were extubated or died. Based on the total mechanical ventilation duration, patients were divided into three groups: Group 1 (3 - 7 days), Group 2 (8 - 15 days), and Group 3 (> 15 days). The patient's total spontaneous ventilation duration (more than 12 hours of ventilation on spontaneous mode comprised one day of spontaneous ventilation) was recorded in days during the mechanical ventilation stay. The duration of diaphragm protective ventilation was defined as the number of days during which the diaphragm thickness fraction remained between 15% and 30%. The primary outcome was to assess the correlation between spontaneous ventilation duration and diaphragm protective ventilation duration. The secondary outcome was the impact of spontaneous ventilation duration on total mechanical ventilation duration, intensive care unit length of stay, and survival.

RESULTS

There was a strong positive correlation between spontaneous ventilation duration and diaphragm protective ventilation duration as well as between spontaneous ventilation duration% and diaphragm protective ventilation duration% in the study population as well as in all three groups (r = 0.96, 0.91, 0.97 and 0.89, respectively; p value < 0.001) and (r = 0.88, 0.86, 0.96 and 0.90, respectively; p value < 0.001), respectively. The crude mortality rate was significantly lower with longer spontaneous ventilation duration (p value < 0.001), and a similar trend was observed in the age, SOFA score, and total mechanical ventilation duration-adjusted mortality.

CONCLUSION

In patients with acute respiratory distress syndrome requiring invasive mechanical ventilation, encouragement of spontaneous ventilation provides diaphragm protection as evidenced by a strong positive correlation between spontaneous ventilation duration and diaphragm protective ventilation duration. In addition, patients with longer spontaneous ventilation duration may experience improved survival. Further research is needed to confirm the findings of the present study.