Effectiveness assessment of a guideline based protocol for ventilatory support management of COPD exacerbations in an emergency department.
Franciele Plachi, Fernando Nataniel Vieira, Danilo Cortozi Berton and 3 others
PMID 28711381WHAT IT FOUND
13 of 109 subjects who started noninvasive ventilation still needed invasive ventilation.
Those who failed had worse outcomes. After starting ventilation, mask tolerance and a 6.5 mmHg carbon dioxide drop predicted success.
Key findings
01Among the 109 subjects receiving NIPPV, 13 (12%) required transition to invasive mechanical ventilation.
02Subjects who failed NIPPV had a 245% higher risk of mortality than subjects with successful NIPPV (Exp(B): 3.45; 95% CI: 1.74 to 6.84; p < 0.001).
03Only NIPPV tolerance and improvement in PaCO2 after 1 h were independently related to NIPPV success; a 6.5 mmHg PaCO2 reduction had sensitivity 87% and specificity 71% for avoiding invasive mechanical ventilation.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
This was a retrospective, single-centre cohort, so it can show associations but cannot prove that the guideline protocol, NIPPV, or transition to invasive ventilation caused the outcomes. The failed NIPPV group had 13 subjects and the initial invasive ventilation group had 8 subjects, so the study had low power to detect differences, especially between those groups. The authors state that protocol violations were more likely in real emergency practice and that some analyses, such as NIPPV duration before intubation, could not be done because records were not trustworthy. No baseline admission variable predicted NIPPV failure, so the useful finding applies to reassessment after ventilation has started, not to choosing patients before treatment. The supplied text does not name a pre-specified primary outcome, so the reported comparisons follow the stated aims rather than a single registered endpoint.
Declared interests
The authors declared no conflicts of interest. The supplied text does not state a funding source.
The easy way to misread this
Do not conclude that a guideline-based protocol or NIPPV improves outcomes in COPD exacerbations. This was an observational cohort, and the worse outcomes in the failed NIPPV group are associations, not proof that NIPPV or the protocol caused harm or benefit. The key predictors were available only after ventilation had started, so they cannot be used as initial triage tools.