Exercise induced bronchoconstriction after hospitalisation for lower respiratory tract infection in infancy

Hospitalisation for bronchiolitis in infancy is a well-known risk factor for
later asthma. Bronchiolitis is a viral lower respiratory tract infection
(VLRTI), affecting infants <2 years of age. Respiratory syncytial virus (RSV)
and rhinovirus (RV) are the predominant viruses, associated with severe VLRTI
in infancy. Few prospective studies have examined the development of asthma in
children with a history of VLRTI by using an exercise provocation challenge,
which is an indirect provocation test highly specific for asthma. These
exercise challenge tests were not standardized and pulmonary function
measurements were performed only 5, 10 and 15 minutes after exercise, which
probably underestimates the prevalence of exercise induced bronchoconstriction
(EIB) in these children.

Main objective of this study is to investigate the prevalence of EIB in young
children with a history of hospitalisation for VLRTI, using an exercise
provocation challenge adjusted to the specific age-related course of EIB.

This study is a prospective cohort study.
Patients will undergo an extensive evaluation of their asthma, including a
history, physical examination and an exercise provocation challenge. This
exercise provocation challenge exists of jumping on a jumping castle for at
least 4 minutes (target is a 6 minute lasting exercise at 80% of the predicted
maximum heart rate). Before, during and after exercise, patients perform
pulmonary function measurements (flow volume curves). Exercise induced
bronchoconstriction is defined as a >13% fall in FEV0.5 after exercise. If
bronchoconstriction persists 15 minutes post-exercise (i.e. FEV0.5 less than
95% from baseline value) or at childrens request, 100 µg salbutamol will be
administered and a flow volume loop will be repeated 5 minutes after salbutamol
to establish recovery.
The exercise provocation challenge takes place in the skating rink, because the
air condition (cold and dry) is standardized and reflects the mean air
condition in Holland (*real life test*). Moreover, an exercise challenge in dry
air is a more sensitive test to diagnose exercise induced bronchoconstriction.
Children with a negative exercise provocation challenge will be invited to a
second challenge on another day, to prevent false negative results.

The intervention is an exercise provocation challenge. This exercise challenge
exists of jumping on a jumping castle for at least 4 minutes (target is a 6
minute lasting exercise at 80% of the predicted maximum heart rate). Before,
during and after exercise, patients perform pulmonary function measurements
(flow volume curves).
The exercise provocation challenge takes place in the skating rink, because the
air condition (cold and dry) is standardized and reflects the mean air
condition in Holland (*real life test*). Moreover, an exercise challenge in dry
air is a more sensitive test to diagnose exercise induced bronchoconstriction.
Children are involved in all kinds of exercise all day long and for children,
exercise is a way of recreation. Our exercise challenge (jumping on a jumping
castle) was especially designed for young children and is a child-friendly and
safe way of exercise. Experience from previous research (a pilot study and
study NL38021.044.11) with the same exercise challenge has learned us that
children enjoy performing the test. For these reasons we believe that our
intervention is not harmful to the children.

The risks of participation are considered minimal.
Patients have to undergo an exercise provocation challenge with the chance of
getting dyspnoeic. Especially in children, exercise limitation is a heavy
burden on the quality of life, however the exercise challenges alone pose a
minimal risk. The possible dyspnoea is comparable to that experienced when
exercising in real life and children generally consider this as a minimal
burden. When indicated (i.e. if bronchoconstriction persists 15 minutes after
exercsie or at patients request) salbutamol will be administered. If children
become dyspnoeic during exercise, exercise will be terminated. With the
development of the design of our exercise provocation challenge, the age of the
children is taken into consideration. We tried to minimize the burden of
exercise by using a jumping castle. Experience from previous research (a pilot
study and study NL38021.044.11) with the same exercise challenge has learned us
that children enjoy performing the test. For these reasons we believe that our
intervention is not harmful to the children.The benefit is that patients (and
parents) get an evaluation of the extent of their asthma. This study must be
performed in this young patient group, because diagnosing asthma at this age
enables early therapeutic intervention, thereby preventing long term
remodelling of the asthmatic airways. Moreover, we would like to compare our
results with the scarce existing data,in this age group.