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How quick is soon? Early response to continuous positive airway pressure: a randomized controlled trial


Numerous studies have confirmed that using non-invasive continuous positive airway pressure (nCPAP) for chronic obstructive pulmonary disease and congestive heart failure improves the respiratory rate, heart rate (HR), and work of breathing. We hypothesize that early application of nCPAP with concomitant medical therapy to patients with acute undifferentiated shortness of breath (SOB) will improve objective measures of respiratory distress. Specifically, early application of nCPAP can improve the tidal volume (TV), end-tidal carbon dioxide (EtCO2) and Rapid Shallow Breathing Index (RSBI), and reduce intubations over the standard of treatment alone in 15 minutes or less.


Fifty-two patients were randomized equally to either CPAP + standard of care (nCPAP group) or to standard of care (standard group) for acute undifferentiated SOB. nCPAP was applied for 15 minutes. Subject enrollment was randomized and demographic data were recorded upon enrollment. Volumetric measures were obtained by breathing through the EtCO2/Flow sensor for 30 seconds at 5-minute intervals along with vital signs. Inclusion criteria were adults >18 years, with acute respiratory distress, admitted to the resuscitation room of the emergency department, respiratory rate > 25 bpm, SpO2 > 75%, Glasgow Coma Score > 8, HR > 60/min, and systolic blood pressure > 90 mmHg. Exclusion criteria were respiratory arrest and/or cardiac arrest, suspected pulmonary embolism, pneumothorax, myocardial infarction, temperature >38.5°C, or refusal to participate.


All tests were two-sided and assessed at the 0.05 type-I error rate. The gender distribution was equal for both groups. There was no difference in baseline characteristics except for age, HR and diastolic blood pressure (P < 0.05). Subjects in the nCPAP group had a greater improvement for various parameters compared with the standard group including TV (0.8 l, 0.3 l), EtCO2 (30 mmHg, 38 mmHg) and RSBI (39, 150), respectively. The nCPAP group also had a shorter hospital and ICU length of stay compared with the standard group (4 vs 5 days, and 2 vs 3 days, respectively). Finally, the rate of intubations was higher in the standard group (n = 8, n = 3) than the nCPAP group (P < 0.01).


The early application of nCPAP in patients with acute undifferentiated SOB improves their volumetric parameters and vital signs in as early as 5 minutes. This pilot study provides objective support for the notion that early application of nCPAP can lead to measurable improvement in TV, EtCO2, RSBI and reductions in intubations.

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Crawford, J., Otero, R., Rivers, E. et al. How quick is soon? Early response to continuous positive airway pressure: a randomized controlled trial. Crit Care 12 (Suppl 2), P344 (2008).

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