The science of breathing: how our brain controls breathing
We are investigating how the brain controls breathing, which will allow us to assist those with breathing difficulties, such as people with spinal cord injuries or disorders such as obstructive sleep apnoea.
Prof Simon Gandevia has taken approximately 413,931,075 breaths in his lifetime – and counting.
Ok, so maybe he’s not exactly counting. But while most of us don’t even notice our breathing, Prof Gandevia has spent his entire working life pondering how it is that we control this very important and often unappreciated process.
“Breathing to me is the most important function of your muscles, apart from your heart,” he says. “It has to go all the time, without conscious thought. It’s controlled differently from the way the muscles in your arms and legs are controlled. Understanding the control of breathing for me is an intellectual challenge.”
Simon’s father was a respiratory physician and a very good teacher who was “happy to show me lots of things”, says Simon, including scientific dissections of animals during school holidays. Simon says these experiences nurtured his innate curiosity about how animals – especially humans – are put together.
“It was very easy to get me intrigued. My interest is really in how biological things work, ultimately how the human body works,” he says.
Fast forward thirty years or so, and Prof Simon Gandevia has amassed a large body of work on this most fundamental of bodily functions. Some of his most impressive research revolves around breathing in people with spinal cord injuries.
If a person is injured high up enough on the spinal cord, they may lose the connection between the brain, which controls automatic breathing, and the nerves in the spinal cord that control muscles used for breathing and coughing.
“To understand what’s gone wrong in these patients, first we need to understand the physiology, so how something works and what happens when it doesn’t work,” he says. “This is what our research is about. It’s very easy to be interested in breathing when you see spinal cord injured people who can’t breathe and can’t cough.”
One such person is Bill Brooks, who became quadriplegic in his late sixties after a sudden head movement, combined with a narrowing of his spinal canal, left him unable to move from the neck down.
Bill had been mired in the intensive care unit for weeks after his accident due to recurrent respiratory infections brought on by his inability to cough and clear his lungs. Desperate, having tried everything, his doctors contacted Simon.
“They rang me up and said, we don’t know what to do about this guy, can you think of anything?” says Simon.
And he did.
“We decided to try and help him cough using some electrical stimulation to train up his abdominal muscles,” says Simon.
This system of electrodes, attached just below the chest, stimulates the muscles to generate coughing-like pressure in the abdomen, which can then lead to relatively normal removal of airway secretions.
“Miraculously or otherwise, after a few weeks of this, we were able to take out his breathing tube and he was able to leave intensive care.”
The experience with Bill and the ‘coughalator’, as the electrical stimulation device was christened, has triggered a series of fruitful research projects for Simon’s team.
“Bill set us off on the whole job of trying to come up with a better system of trying to help patients with spinal cord injury cough,” says Simon.
Simon and PhD candidate, Rachel McBain, have subsequently shown that electrical stimulation can be used as part of an ongoing ‘ab workout’ regime to further increase the strength of the cough. In the long term, they hope to develop a self-triggered, portable device to offer even greater independence to people like Bill with high level spinal cord injuries.
“This kind of technology can lead to a longer and better quality of life,” says Simon.
Breathing in your sleep
Another of Simon’s research focuses is breathing in obstructive sleep apnoea, a disorder where the muscles of the throat and upper airway repeatedly collapse during sleep, leading to a decrease in the amount of oxygen in the blood.
More than just an extreme form of snoring, obstructive sleep apnoea can lead to accidents due to fatigue, hypertension, even heart attack and stroke.
Simon is working with NeuRA’s resident tissue mechanics expert, Prof Lynne Bilston, to understand how changes in the mechanical properties of the upper airway muscles, as well as how the brain drives these muscles, combine to cause this condition.
Using MRI to observe the movement of the upper airway muscles during normal breathing, Prof Bilston is gaining a better understanding of what predisposes them to collapse. With his background in the neural control of breathing, Simon is able to measure the signals the brain sends to the major muscle in the upper airway, the genioglossus, that cause it to contract with breathing and keep the upper airway open.
This cross-disciplinary approach allows them to measure the interaction between the brain and the upper airway muscles, which will assist in developing more effective treatments for obstructive sleep apnoea.
As Simon can attest, it’s collaborative methods like this – and the occasional unexpected challenge like Bill Brooks – that can lead to the most interesting outcomes in research.
As Bill puts it, “What they do is full on. I didn’t know what I was getting in to, but it worked. It’s a good team they’ve got down there.”