A new study shows that using a transparent air-tight helmet instead of a face mask helps critically ill patients breathe better and can prevent them from needing a ventilator. Patients with helmet ventilation also spent less time in the intensive care unit and had better survival.
The study followed 83 patients suffering from acute respiratory distress syndrome (ARDS), a severe, often lethal, injury to the lungs. ARDS causes fluid to accumulate in the lungs’ microscopic air sacs. It can lead to partial collapse of the lungs, dangerously low blood-oxygen levels and death.
The subjects in this study all required mechanical breathing assistance. They were randomly assigned to receive some form of non-invasive ventilation, using either a standard mask, strapped onto the face and covering the nose, mouth and chin; or the helmet, which surrounds the patient’s entire head and is sealed with a soft air-tight collar that wraps around the patient’s neck.
A primary goal of non-invasive ventilation is to prevent intubation, placement of a tube through the mouth or nose into the trachea to pump air into the lungs. Complications of endotracheal intubation are common. They include pneumonia, the need for strong sedatives, and delirium.
“In this group of critically ill patients, the helmet made a substantial difference,” said pulmonologist Dr John P Kress, professor of medicine at the University of Chicago and senior author of the study. “The University’s data and safety monitoring board recommended that we stop the trial early because the helmet consistently demonstrated multiple advantages, particularly the reduced need to intubate patients and longer-term reduction in mortality.”
“After reviewing our data,” he added, “the board felt that it would be difficult to justify enrolling more patients in the face-mask arm of the trial, which exposed them to greater risks.”
The helmet “confers several advantages over the face mask,” the authors wrote. It is less likely to leak. This enables the care team to increase air pressure into the helmet, which helps keep the airway and lungs open and improves oxygen levels. It is also more comfortable, easier to tolerate because it doesn’t touch the face, and patients can see through it well enough to watch television, talk or read.
Patients who required the face mask for oxygenation for at least 8 hours were eligible to enrol in the study. Forty-four of the 83 patients who qualified to participate were then randomly assigned to the helmet group. The other 39 were assigned to the face-mask group.
All patients were severely ill with a 50% risk of requiring intubation or dying in the intensive care unit. About half of the patients had weakened immune systems from cancer or transplantation.
Patients in the helmet group, however, were three times less likely to require intubation, the study’s primary endpoint. Only 18.2% of those wearing a helmet required an endotracheal tube, versus 61.5% of those wearing a face mask. The helmet group had, on average, more ventilator-free days (28 vs 12.5).
Helmet patients were also more likely to survive. When compared at 90 days, 34% (15 patients) in the helmet group had died, compared to 56% (22 patients) in the face mask group. Adverse trial-related events were minor. They included 3 skin ulcers for each group.
“The helmet interface has unique advantages and disadvantages,” wrote Dr Jeremy Beitler, of the University of California, San Diego, in an accompanying editorial. “Careful selection of patients is important.” This approach, he wrote, “warrants testing in a multicentre trial.”
“These findings build on a shifting paradigm where less is more in the care of critically ill patients,” said Dr Bhakti Patel, clinical instructor of medicine at the university and first author of the study. “We have chosen less sedation for more mental animation; less bed rest for more physical activity; and now we’re choosing less intubations for more noninvasive ventilation.”
The helmets used in this study are distributed by Sea-Long Medical Systems Inc, based in Louisville, Kentucky. One helmet costs about $100.
Importance: Noninvasive ventilation (NIV) with a face mask is relatively ineffective at preventing endotracheal intubation in patients with acute respiratory distress syndrome (ARDS). Delivery of NIV with a helmet may be a superior strategy for these patients.
Objective: To determine whether NIV delivered by helmet improves intubation rate among patients with ARDS.
Design, Setting, and Participants: Single-center randomized clinical trial of 83 patients with ARDS requiring NIV delivered by face mask for at least 8 hours while in the medical intensive care unit at the University of Chicago between October 3, 2012, through September 21, 2015.
Interventions: Patients were randomly assigned to continue face mask NIV or switch to a helmet for NIV support for a planned enrollment of 206 patients (103 patients per group). The helmet is a transparent hood that covers the entire head of the patient and has a rubber collar neck seal. Early trial termination resulted in 44 patients randomized to the helmet group and 39 to the face mask group.
Main Outcomes and Measures: The primary outcome was the proportion of patients who required endotracheal intubation. Secondary outcomes included 28-day invasive ventilator–free days (ie, days alive without mechanical ventilation), duration of ICU and hospital length of stay, and hospital and 90-day mortality.
Results: Eighty-three patients (45% women; median age, 59 years; median Acute Physiology and Chronic Health Evaluation [APACHE] II score, 26) were included in the analysis after the trial was stopped early based on predefined criteria for efficacy. The intubation rate was 61.5% (n = 24) for the face mask group and 18.2% (n = 8) for the helmet group (absolute difference, −43.3%; 95% CI, −62.4% to −24.3%; P < .001). The number of ventilator-free days was significantly higher in the helmet group (28 vs 12.5, P < .001). At 90 days, 15 patients (34.1%) in the helmet group died compared with 22 patients (56.4%) in the face mask group (absolute difference, −22.3%; 95% CI, −43.3 to −1.4; P = .02). Adverse events included 3 interface-related skin ulcers for each group (ie, 7.6% in the face mask group had nose ulcers and 6.8% in the helmet group had neck ulcers).
Conclusions and Relevance: Among patients with ARDS, treatment with helmet NIV resulted in a significant reduction of intubation rates. There was also a statistically significant reduction in 90-day mortality with helmet NIV. Multicenter studies are needed to replicate these findings.
Bhakti K Patel, Krysta S Wolfe, Anne S Pohlman, Jesse B Hall, John P Kress