Research summary – Morgan Walker

Airways Obstruction and Pulmonary Capillary Blood Volume in Children With Sickle Cell Disease

Catherine Wedderburn, David Rees, Susan Height, Moira Dick, Gerrard F. Rafferty, Alan Lunt, Anne Greenough

Published in the journal Pediatric Pulmonology, published online July 10th 2013

Children with Sickle Cell Disease (SCD) often face many obstacles due to the changes the condition causes in the body’s red blood cells. SCD results in anaemia, which is when there is less haemoglobin in the blood to help carry oxygen around the body. As a result, the heart has to pump much harder in order to ensure that the tissues of the body receive enough oxygen. This increased work by the heart also raises the amount of blood in the lungs, in order to allow sufficient oxygen is absorbed from the air. Children with SCD also frequently experience ‘airway obstruction’, which is the narrowing of the airways that makes it then harder to breathe. Airway narrowing can be caused by asthma, where muscles in the airways constrict, or by other causes.

This research was used to investigate whether the increased blood volume in lungs is associated with the ‘obstruction’ of the airways. The researchers tested this through testing the difference in the airways before and 30 minutes after using a medication called a bronchodilator (the blue asthma ‘reliever’ inhaler) which relaxes the airway muscles, widening the airways.   The study used measurements called spirometry, which tests the amount and speed of air that can be moved in and out of the lungs, and Impulse Oscillometry (IOS), which uses sound waves in order to assess the resistance of the airways (airway narrowing).

If the bronchodilator had a substantial effect, the researchers would be able to say that the airway obstruction was due to an asthma-type condition, as the inhaler would have relaxed the muscles and allowed air to move more easily through the airways. What the results showed, however, was that there was little change in the measurements of lung function after the inhaler was given. The researchers can therefore use this evidence to support the hypothesis that the airway obstruction in SCD may be due to increased blood volume in the lungs.

Therefore, this study suggests that treatment of non-asthma related airway obstruction in SCD patients could perhaps move away from bronchodilators and towards more effective treatments for the anaemia aspect of SCD such as blood transfusions. A great deal of further work is needed but this is a valuable insight into the a potential process underlying breathing problems in SCD.

This summary was produced by Morgan Walker, Year 13 student from Harris City Academy Crystal Palace, as part of our departmental educational outreach programme.

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