- The beneficial effects of heliox are felt to be related to the lower
density of helium, which preserves laminar flow at higher flow rates,
decreasing work of breathing by decreasing resistance to airflow.
- The study is quite small, and patients were not randomized. The small
sample size produced an inability to assess direct outcomes, such as
mortality or intubation rates. Instead, the surrogate end point of a
clinical asthma score (although a relatively well-validated one) was
used. The patients in the treatment group were all enrolled after the
control group, leading to the possibility of changing practices in terms
of conventional management, and or PICU discharge results skewing the
- Children with chronic cardiac or pulmonary disease were excluded from
the study, which likely contributes to the fact that none of the infants
in either group progressed to requiring intubation.
- Heliox administration requires use of a facemask, which may not be
well tolerated by all infants.
- The study was not blinded, due to the use of a facemask with heliox,
and changes in voice/cry related to helium.
F, Rodriguez-Nunez A, Martinon-Sanchez JM. Heliox therapy in infants
with acute bronchiolitis. Pediatrics 2002; 109(1): 68-73.