Continuous positive airway pressure versus continuous negative pressure around the chest for patients with acute exacerbation of chronic obstructive pulmonary disease in the intensive care unit: A pilot study.

Introduction. With chronic obstructive pulmonary disease (COPD) exacerbations, continuous positive airway pressure (CPAP) has been used to overcome the threshold load provided by intrinsic positive end expiratory pressure and decrease the inspiratory work of breathing. In this pilot study, we observed whether a continuous negative pressure (CNP) around the thorax and upper abdomen with a shell and wrap would provide a similar level of relief in dyspnoea. Methods. In eight patients with COPD in the intensive care unit receiving CPAP, CNP was alternated twice with CPAP (30 minutes each time). We measured heart rate, respiratory rate, blood pressure, arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), pH and dyspnoea score, and asked each patient which system was more comfortable. Results. Comparing CPAP with CNP, we found no significant difference in all measured parameters except PaCO2 which was lower with CNP. Seven out of eight patients found that CNP was more comfortable. Conclusions. The CNP was similar to CPAP except CNP was more comfortable.