Lunt A, Desai SR, Wells AU, Hansell DM, Mushemi S, Melikian N, Shah AM, Thein SL, Greenough A (2014) Pulmonary function, CT and echocardiographic abnormalities in sickle cell disease Thorax 69(8): 746-51
This project looked at how well the lungs were working in people with sickle cell disease (SCD). This disease makes people anaemic (they don’t have as many red blood cells as normal) and means that it’s harder for the blood to carry oxygen to all the organs and tissues. The body tries to compensate for this by making more blood and pumping it round much faster than normal.
We know that some people with SCD develop breathing problems, but we don’t understand what causes them. By doing lung function tests (which measure things like the size of the lungs, how fast you can blow out and how easily you can take up oxygen into the blood) we can find out how well the lungs are working. This study did lung function tests on some adults with sickle cell disease, but also took images of the lungs and heart using CT scanning (a fancy 3-D x-ray) and ultrasound (which looks at how sound waves bounce off tissues). This meant that we could see if the problems with how the lungs worked were explained by how they were put together. In most of the patients the lung tissue didn’t look very abnormal but the blood vessels in the lung were much bigger than expected. What was most interesting was that the more enlarged a person’s blood vessels were, the worse their lung function was. We think that these big blood vessels start to squeeze the airways and stop air moving in and out freely. We also found that the blood vessels got bigger when the heart had problems dealing with all the blood it had to pump. This means that to understand why people with sickle cell disease have breathing problems, we can’t just look at the lungs: we have to understand the complex ways that the lung, heart, and blood vessels interact.
Kassim Z, Moxham J, Davenport M, Nicolaides K, Greenough A & Rafferty GF. (2015) Respiratory muscle strength in healthy infants and those with surgically correctable anomalies. Pediatric Pulmonology 50(1):71-8
Some babies are born without the muscles across the front of the tummy or the main breathing muscle (the diaphragm) being completely formed. When this happens, the breathing muscles often can’t work as well as they should and these babies can get (sometimes quite bad) problems with their breathing. Knowing how much the breathing muscles are affected can be helpful in giving these babies the right treatment. This study looked at how strong the breathing muscles were in healthy babies and babies with these muscle problems. The healthy babies had breathing muscles that were not much weaker than adults’ muscles, and they got even stronger 6 weeks after they were born. The babies with the muscle problems were weaker, though got stronger by 6 weeks. Their muscles getting stronger was related to their lungs working better.
Reilly CC, Jolley CJ, Ward K, MacBean V, Moxham J & Rafferty GF. (2013) Neural respiratory drive measured during inspiratory threshold loading and acute hypercapnia in healthy individuals. Experimental Physiology 98: 1190-1198
This study took healthy people and gave their breathing muscles extra work to do in two different ways – one where the people had to breathe from a box that we were sucking the air out of with a hoover, and the other where we gave people extra carbon dioxide to breathe – this makes you breathe deeper and faster as your body tries to get rid of the extra carbon dioxide, which is normally a waste gas. We do studies like this to try and recreate what happens in the bodies of people with lung problems, but by doing it in the laboratory we can change one thing at a time and in a more controlled way. The results from this project gave us important information about how the main breathing muscle (the diaphragm) works together with some of the other breathing muscles at the front of the chest. This means we can make better decisions about which muscles to measure in other studies.
Seymour JM, Ward K, Raffique A, Steier J, Sidhu PS, Jolley CJ, Polkey MI, Moxham J & Rafferty GF. (2012). Quadriceps and ankle dorsiflexor strength in chronic obstructive pulmonary disease. Muscle and Nerve 46: 548-554.
This project studied the strength of two different leg muscles (the muscles at the front of the thigh (“quadriceps“) and shin muscle (“tibialis anterior“)) in healthy older people and people with Chronic Obstructive Pulmonary Disease (COPD). The patients with COPD had weaker thigh muscles, but their shin muscles were no different to the healthy people. We knew previously that thigh muscles of patients with COPD tend to be weaker than in healthy people, probably because when you have lung disease you tend to walk around less and so your muscles can become weak. This study is important as it tells us that not all muscles change the same if you become unwell and do less exercise.