ľ��ֱ��

Helmet-based ventilation eases respiratory distress

The noninvasive ventilation helmet is a transparent hood that covers the entire head of the patient and has a rubber collar neck seal.The University of Chicago Medicine

Acute respiratory distress syndrome (ARDS) is a life-threatening condition that occurs when fluid builds up in your lungs. The fluid blocks oxygen from entering your bloodstream and circulating to your body’s organs. If you don’t receive enough oxygen, your organs can’t function properly.

ARDS can be treated with noninvasive ventilation methods—for example, through a mask that fits over your mouth and nose. But many patients with ARDS aren’t helped by face mask ventilation and require a more invasive procedure called intubation, in which a breathing tube is inserted through the mouth or nose and into the windpipe. The tube is connected to a ventilator that pumps oxygen-rich air into the lungs. Intubated patients are usually sedated and bedridden. The process can cause discomfort and other problems, including muscle deterioration and mental confusion.

To investigate whether noninvasive ventilation using a helmet may be more effective than with a face mask, a team of scientists from the University of Chicago led by Dr. John P. Kress conducted a randomized clinical trial of patients with ARDS. The research was funded in part by NIH’s National Heart, Lung, and Blood Institute. Results were published online in the Journal of the American Medical Association on May 15, 2016.

Researchers screened patients admitted to the intensive care unit. Those with ARDS who needed ventilation via a face mask for at least 8 hours were eligible to enroll in the study. A total of 83 patients (median age 59 years) were selected and randomly assigned to either continue receiving ventilation with a face mask (39 patients) or switch to a latex-free helmet (44 patients). Doctors delivered ventilation to both groups according to a standard protocol until oxygen levels reached above 90%. Patients were intubated if they had persistent or worsening respiratory failure, an intolerance for the face mask or helmet, neurologic deterioration, airway bleeding, or excessive respiratory secretions.

Intubation was necessary for 24 of the patients wearing a face mask (62%), but for only 8 of those with a helmet (18%). Patients with helmets also had more ventilator-free days on average (28 vs. 12.5) and spent significantly less time in the intensive care unit (4.7 day median vs. 7.8). The helmet group had 15 patient deaths (34%) over the 90 days following treatment randomization, compared to 22 deaths (56%) in the face mask group.

“In this group of critically ill patients, the helmet made a substantial difference,” Kress says. “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.”

Multicenter trials will be needed to confirm these results and standardize the procedures before the helmet could be used routinely in intensive care units. In addition, the helmet’s benefits need to be compared with another technique called high-flow nasal cannula treatment, which uses nasal prongs to deliver oxygen.

—by Tianna Hicklin, Ph.D.