Helmet CPAP Leads Noninvasive Ventilation Therapies for Acute Respiratory Failure

The available noninvasive oxygenation strategies varied in their effectiveness in treating acute hypoxemic respiratory failure (AHRF), according to a meta-analysis of randomized trials.

Helmet continuous positive airway pressure (CPAP) was the only modality that had at least moderate certainty evidence backing a probable mortality reduction compared with standard oxygen therapy (SOT; 231 fewer deaths per 1,000), reported Tyler Pitre, MD, of McMaster University in Hamilton, Ontario, and coauthors.

Nevertheless, high-flow nasal cannula (HFNC; 103.5 fewer events per 1,000) and face mask bilevel ventilation (99 fewer events per 1,000) were the only therapies associated with lesser need for invasive mechanical ventilation with the threshold of moderate-level evidence, according to the meta-analysis published in CHEST.

“Based on the available evidence, the helmet interface is likely superior compared to the facemask interface,” Pitre’s group wrote. “However, this has only been studied in [a] few small, randomized trials.”

None of the five oxygenation strategies studied — HFNC, helmet bilevel ventilation, helmet CPAP, face mask CPAP, and face mask bilevel ventilation — had any better than low-certainty evidence to suggest shorter intensive care unit (ICU) and hospital stays, more ventilator-free days, and greater patient comfort compared with SOT.

The authors highlighted the importance in reducing need for invasive mechanical ventilation and shortening ICU stays following the COVID-19 pandemic. They also encouraged updating current guidelines to clarify use of noninvasive oxygenation strategies and advocated for further research on the matter.

“This review has the potential to change practice in prioritizing HFNC for AHRF and further demonstrating the need to gain comfort and expertise with the helmet interface for NIV [noninvasive ventilation] delivery. Current ERS/ATS [European Respiratory Society/American Thoracic Society] guidelines on noninvasive ventilation for acute respiratory failure do not specify interfaces for noninvasive ventilation,” according to Pitre and colleagues.

“Given the present analysis and the lessons learned from COVID studies, updates of guidelines addressing AHRF are required to guide clinicians and healthcare systems to allocate appropriate resources,” they said.

A total of 36 trials and their 7,046 adult participants were included in the meta-analysis. The median patient age was 59 years and 61% of participants were men.

Of the trials analyzed, 30 included patients who were exclusively randomized in the ICU, four included a mix of ICU and medical ward patients, and two included ward patients only.

Eleven trials focused largely on pneumonia cases, and eight studied patients with COVID-19. Six trials included individuals with chronic obstructive pulmonary disease, type 2 respiratory failure, and congestive heart failure.

In terms of ventilation method used, 20 trials studied face mask bilevel ventilation, 19 studied HFNC, four covered helmet bilevel ventilation, four covered face mask CPAP, and two included helmet CPAP.

Pitre and colleagues acknowledged that blinding was not possible for the trials included in the meta-analysis, leading to a potential for bias. Researchers also noted that there was a high degree of heterogeneity in their study population, as well as a wide array of causes for a patient to develop AHRF, which may further limit findings.