Helmet vs. Mask interface for Acute Hypoxemic Respiratory Failure in COVID-19 patients: Is there a difference?

Saudi Arabia: A study published in JAMA evaluated the comparison between noninvasive helmet ventilation and usual respiratory support to be insignificant in reducing 28-day all-cause mortality in patients with acute hypoxemic respiratory failure due to COVID-19 pneumonia.

Helmet ventilation delivers prolonged treatment with high positive airway pressure and is associated with fewer air leaks and better fitting for facial contouring. This is widely used in Italy. The use of helmet ventilation has increased during COVID-19. The US FDA, in March 2020, issued Emergency Use Authorizations to several manufacturers regarding helmet use in an acute hypoxemic respiratory failure resulting from COVID-19. However, the available data supporting helmet ventilation in reducing mortality and endotracheal intubation comes from the non-COVID-19 population. The availability of data from COVID-19 patients on the effectiveness of helmet ventilation is unclear.

The study conducted by Arabi et al. and the team from the Intensive Care Department of the Ministry of National Guard Health Affairs, King Abdullah International Medical Research Centre, and King Saud Bin Abdulaziz University for Health Sciences compared noninvasive helmet (Subsalve) ventilation and usual respiratory support in reducing 28-day mortality in patients with acute hypoxemic respiratory failure due to COVID-19 pneumonia.

The study was conducted at seven sites in Saudi Arabia and 1 in Kuwait. A total of 322 patients were randomized. Of these patients, 159 were in the noninvasive helmet group, and 161 were in the usual respiratory support group. The patients enrolled had a ratio of PaO2 to Fraction of Inspired Oxygen (FIO2) <200. In the helmet, noninvasive ventilation group, initial settings of pressure support were 8 to 10 cm H20 and positive end-expiratory pressure (PEEP) of 10 cm H20 with FIO2 of 1.0

When required, PEEP and pressure support were increased by 2 cm H2O every 3 minutes to achieve oxygen saturation greater than or equal to 90 % on FIO2 less than or equal to 0.6 and achieving respiratory rate less than or equal to 25/minute with the disappearance of accessory muscle activity, respectively. The maximum allowed sum of PEEP and pressure support was 30 cm H2O.

28-day-all-cause mortality was the primary outcome measured with 12 prespecified secondary outcomes, including endotracheal intubation.

The critical points of the study include:

• The patient included had a median age of 58 years and were 41.6 % women and 58.4 % men.

• All 320 patients completed the study.

• Dexmedetomidine infusion was permitted in the helmet noninvasive ventilation group, but intravenous sedatives like benzodiazepines or narcotics were not allowed.

• Seven patients (4.6 %) who initially agreed to Helmet noninvasive ventilation later declined .

• 36.5 % (58 patients) discontinued the helmet because of intolerance after 20.5 hours of usage.

• The percentage of death in 28 days was 27 % (43 patients) and 26.1 % (42 patients) in the noninvasive helmet ventilation and usual respiratory support groups, respectively. The risk difference was 1 %, with a relative risk of 1.04. The P value was equal to 0.85. This was the primary outcome recorded.

• The use of Helmet noninvasive ventilation in the usual respiratory support group was infrequent, accounting for 2.5 %.

• Seventy-five patients (47.2 %) required endotracheal intubation in the helmet ventilation group compared to 81 patients (50.3%) in the usual respiratory support group. The risk difference was -3.1 %, with a relative risk of 0.94. These findings were recorded within 28 days.

• Between the two groups, no significant differences were observed in serial respiratory rate, the ratio of oxygen saturation to FIO2, device discomfort visual analog scale scores, SOFA (Sequential Organ Failure Assessment) scores, and PaCO2 level.

• Barotrauma occurred in 30 patients (18.9 %) in the helmet noninvasive ventilation group compared to 25 patients (15.5 %) in the usual respiratory support group.

• Skin pressure injury was 3.1 % in the helmet noninvasive ventilation group compared to 6.2 % in the usual respiratory support group.

• There were two serious adverse events in the helmet ventilation group compared to one in the usual respiratory support group.

The length of hospital stay was not significant statistically between the two groups.

The researcher concluded, "Helmet noninvasive ventilation did not significantly reduce 28-day mortality compared with usual respiratory support among patients with acute hypoxemic respiratory failure due to COVID-19 pneumonia."

The limitations of the study were the inadequate sample size, nature of the intervention, lack of direct comparison, a shorter period of training on helmet use, and a moderate level of PEEP.

The interpretation is limited by imprecision in the effect estimate, which does not exclude potentially clinically important benefit or harm." Researchers added.

Reference:

Arabi YM, Aldekhyl S, Al Qahtani S, et al. Effect of Helmet Noninvasive Ventilation vs. Usual Respiratory Support on Mortality Among Patients With Acute Hypoxemic Respiratory Failure Due to COVID-19: The HELMET-COVID Randomized Clinical Trial. JAMA. 2022;328(11):1063–1072.