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Ahead of Our Time

Evaluating the effectiveness of delivering medications to the lungs of children

Asthma is the most common chronic disease in children, affecting nearly 850,000 Canadian children under the age of 14. At its worst, asthma can cause a child’s airways to narrow so much that they need emergency medical care to breathe, but even milder symptoms can cause children to lose school days, sleep poorly, and experience long-term lung damage.

To protect children from these complications, doctors must diagnose and treat asthma as soon as possible. One medical test doctors use is called a bronchoprovocation test.

“During the test, the child breathes in a mist or spray from a nebulizer that contains a small amount of an agent called methacholine in it and then doctors perform additional tests to see how the lungs react,” explains Andrew Martin, director of the University of Alberta’s Aerosol Research Laboratory of Alberta.

If the airways of the lungs are hyperresponsive, methacholine can make it harder to breathe, which can help doctors decide whether or not the child has asthma.

“This can make it hard for doctors to interpret test results across labs, but it also puts children at risk of adverse reactions – like fainting and chest pain – if they receive too much methacholine.”

The trouble is that different nebulizers vary in terms of how much medication they can transport to the lungs and different laboratories use different nebulizers,” says Martin. This can make it hard for doctors to interpret test results across labs, but it also puts children at risk of adverse reactions – like fainting and chest pain – if they receive too much methacholine.

“These aerosols are quite complex,” says Martin, a mechanical engineering professor who specializes in designing and testing aerosol-based medical devices, like nebulizers.

Like most medical devices, nebulizers are typically designed for adults, not children.

With funding from a WCHRI Innovation Grant, he and his team developed computer models that predict how much medication is deposited into the lungs when using specific nebulizers.

Martin’s graduate student Kineshta Pillay is focusing on inhaled drug delivery for children and is creating a computational model that incorporates physiological differences related to child development.

“Children aren’t miniature adults,” she says, noting that how well medications reach the lungs is impacted by a child’s age and development. For instance, children have a smaller and shorter airway and faster breathing rate than adults.

Now that the models have been developed and validated, Martin is exploring other nebulizer-related collaborations with clinical partners on campus, especially the University of Alberta Hospital’s Pulmonary Function Lab. The lab, which performs bronchoprovocation tests in children and adults, sparked this research study when they approached Martin for help evaluating a new nebulizer.

“This area of research is important for the health of children with and without asthma,” says Eric Wong, a pulmonologist and medical director of the Pulmonary Function Lab. “At the moment, misdiagnoses could be occurring as a result of nebulizers administering either too much or too little methacholine.”

As a result, healthy kids could receive an incorrect diagnosis of asthma and medication treatments they don’t need. But it’s also possible for asthmatic kids to be deemed healthy when they desperately need treatment. Unfortunately, untreated asthma leads to chronic lung inflammation that may cause permanent narrowing of the airway.

“We want to make the diagnosis early and get children treatment to prevent long-term damage,” says Wong. He adds that since asthma causes breathing difficulties, undiagnosed children may struggle to participate in physical activity, which all kids need to be healthy: “This can have long-term consequences in terms of health, weight gain, and other issues. Making that asthma diagnosis early can avoid these problems and allow kids to participate in activities normally.”

Andrew Martin was supported by the Stollery Children’s Hospital Foundation through the Women and Children’s Health Research Institute.

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