The application of improved Glasgow coma scale score of 15 as switching point for invasive noninvasive mechanical ventilation in treatment of severe respiratory failure in chronic obstructive pulmonary disease

Objective To estimate the feasibility and the efficacy of early extubation and the sequential non-invasive mechanical ventilation (MV) in severe respiratory failure of chronic obstructive pulmonary disease (COPD) with the improved Glasgow coma scale (GCS) score of 15 as the switching point. Methods By a prospective control study, 20 patients with COPD and respiratory failure who had undergone endotracheal intubation and MV from March 2007 to November 2009 were enrolled as treatment group.Invasive MV with synchronous intermittent mandatory ventilation and pressure support ventilation (SIMV+PSV) pattern were given to these patients. When the period of "improved GCS score of 15 standard" window period appeared and being kept for 2 hours, endotracheal tube was extubated, and nasal mask with PSV±positive end-expiratory pressure (PEEP) was used, followed by gradual decrease of the level of pressure support till weaning of MV. Nineteen patients who were treated with MV with ordinary way of weaning from March 2005 to March 2007 served as the control group. Prior to the MV, the ventilation and oxygenation index, the length of invasive MV, total MV time, total hospital stay, re-intubation and ventilator-associated pneumonia (VAP) occurred in the number of cases were observed and compared between two groups. Results There was no significant difference in the ventilation and oxygenation index prior to the MV. Compared with control group, in treatment group, the length of invasive ventilation (days: 3. 2±1.1 vs. 10. 5± 3. 2),the total duration of MV (days: 4. 8±2. 5 vs. 10. 5±3. 2), the length of hospital stay (days:17±3 vs. 22±7) were significantly shorter (all P＜0.01), and the incidence of VAP was significantly lower (cases: 0 vs.5, P＜ 0. 01), while the number of re-intubation was slightly higher but without statistical significance (cases:3 vs. 1, P＞0. 05). Conclusion The application of improved GCS score of 15 as the switching point with 2 hours as window period for early extubation and non-invasive nasal mask ventilation can significantly improve the therapeutic effect in patients with severe respiratory failure in COPD. Key words: Chronic obstructive pulmonary disease; Respiratory failure; Mechanical ventilation; Improved Glasgow coma scale score ; Ventilator weaning