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 Paco2
(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,
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.