Non-invasive negative and positive pressure ventilation in the treatment of acute on chronic respiratory failure.

OBJECTIVE: To investigate in clinical practice the role of non-invasive mechanical ventilation in the treatment of acute respiratory failure on chronic respiratory disorders. DESIGN: An 18 months prospective cohort study. SETTING: A specialised respiratory intensive care unit in a university-affiliated hospital. PATIENTS: A total of 258 consecutive patients with acute respiratory failure on chronic respiratory disorders. INTERVENTIONS: Criteria for starting non-invasive mechanical ventilation and for endotracheal intubation were predefined. Non-invasive mechanical ventilation was provided by positive pressure (NPPV) ventilators or iron lung (NPV). RESULTS: The main characteristics of patients (70% with chronic obstructive pulmonary disease) on admission were (mean, SD or median, 25th-75th centiles): pH 7.29 (0.07), PaCO(2) 83 mm Hg (19), PaO(2)/FiO(2) 198 (77), APACHE II score 19 (15-24). Among the 258 patients, 200 (77%) were treated exclusively with non-invasive mechanical ventilation (40% with NPV, 23% with NPPV, and 14% with the sequential use of both), and 35 (14%) with invasive mechanical ventilation. In patients in whom NPV or NPPV failed, the sequential use of the alternative non-invasive ventilatory technique allowed a significant reduction in the failure of non-invasive mechanical ventilation (from 23.4 to 8.8%, p=0.002, and from 25.3 to 5%, p=0.0001, respectively). In patients as a whole, the hospital mortality (21%) was lower than that estimated by APACHE II score (28%). CONCLUSIONS: Using NPV and NPPV it was possible in clinical practice to avoid endotracheal intubation in the large majority of unselected patients with acute respiratory failure on chronic respiratory disorders needing ventilatory support. The sequential use of both modalities may increase further the effectiveness of non-invasive mechanical ventilation.

Iron lung vs mask ventilation in the treatment of acute on chronic respiratory failure in COPD patients: a multicenter study.

STUDY OBJECTIVES: Evaluation of the effectiveness of negative-pressure ventilation (NPV) with the use of the iron lung vs noninvasive positive-pressure ventilation (NIPPV) in the treatment of COPD patients with acute on chronic respiratory failure. DESIGN: A retrospective case-control study. SETTING: Four Italian respiratory intermediate ICUs. PATIENTS: Of a total of 393 COPD patients admitted to the ICU in 1996, 53 pairs were treated with the iron lung (NPV group). Patients treated with NIPPV (NIPPV group) were matched according to mean (+/- SD) age (70.3 +/- 7.1 vs 70.3 +/- 6.9 years, respectively), sex, causes of acute respiratory failure (ARF), APACHE (acute physiology and chronic health evaluation) II score (22.4 +/- 5.3 vs 22.1 +/- 4.6, respectively), pH (7.26 +/- 0.05 vs 7.27 +/- 0.04, respectively), and PaCO(2) (88.1 +/- 11.5 vs 85.1 +/- 13.5 mm Hg, respectively) on admission to the ICU. The effectiveness of matching was 98.4%. RESULTS: Five patients from the NPV group (9.4%) and seven patients from the NIPPV group (13.2%) needed endotracheal intubation (EI). The treatment failure rate (ie, death and/or need of EI) was 20.7% in the NPV group and 24.5% in the NIPPV group (difference was not significant). The mean duration of mechanical ventilation (29.6 +/- 28.6 vs 62.3 +/- 35.7 h, respectively) and length of hospital stay (10.4 +/- 4.3 vs 15 +/- 5.2 d, respectively) among the 35 concordant surviving pairs were significantly lower in the NPV group than in the NIPPV group (p = 0.001 and p = 0.001, respectively). CONCLUSIONS: These data suggest that both ventilatory techniques are equally effective in avoiding EI and death in COPD patients with ARF. Prospective trials are needed to confirm these preliminary results.