SLEEP_DSC_8903

Sleep apnoea

HEALTH INFORMATION

Improving treatments for obstructive sleep apnoea

WHAT WE KNOW

Obstructive sleep apnoea is more than just an extreme form of snoring. In this disorder, the muscles in the throat and upper airway repeatedly collapse while you sleep, leading to a decrease in the amount of oxygen in your blood. This also partially rouses you from sleep many times a night and leads to poor sleep and an increased risk of accidents, hypertension, heart attack and stroke.

While there are several treatments available for obstructive sleep apnoea, we don’t truly understand how the muscles of the upper airway cause the condition.

We are currently making the first direct biomechanical measurements of the upper airway in humans. By examining how the mechanical properties of these muscles are altered in people with obstructive sleep apnoea and how the brain drives these muscles, we will be able to improve treatments.

OUR LATEST RESEARCH

Control of the neural drive to human breathing muscles in disorders such as obstructive sleep apnoea

Obstructive sleep apnoea is a sleep disorder that affects more than 4% of the population and can lead to symptoms from daytime drowsiness to high blood pressure. People with sleep apnoea are often not breathing normally during sleep and may experience periods where the airway closes and they are unable to breathe. In severe sleep apnoea this can occur 50-60 times each hour. That is once each minute. The closure of the upper airway is thought to be due to a number of factors, one of which is that the neural drive to the airway muscles is insufficient in people with sleep apnoea. In our lab, we have made the first extensive recordings from the major muscle of the upper airway, genioglossus. We have shown that the neural drive to this muscle is very complex, more so than any limb muscle. At NeuRA, we have also pioneered new methods to image this muscle using fMRI and ultrasound. We are now planning to look at how changes in muscle architecture and mechanics relate to the neural drive to the muscle and whether that relationship is maintained in people with sleep apnoea.

The effect of respiratory muscle training on respiratory health after spinal cord injury

After cervical spinal cord injury (SCI), the respiratory muscles are partly or completely paralysed. This has two major clinical consequences: a decreased ability to get air into the lungs and a decreased ability to cough and remove secretions. This results in a lifetime of recurrent respiratory tract infections (2/year/person) that often progress to pneumonia with frequent and extended hospital admissions. People with cervical SCI are 150 times more likely to die from respiratory complications than the general population, as many as 28% die within the first year after injury. For those that survive the first year, a cervical SCI has a lifetime cost of $9.5million, a large proportion of which is attributed to respiratory-related complications. A recent longitudinal study of people with cervical SCI showed that respiratory muscle weakness is associated with incidental pneumonia. Respiratory muscle weakness also causes dyspnoea (breathlessness) and sleep-disordered breathing, which is 4-10 times more prevalent in people with SCI than the able-bodied population. Therefore, there is an urgent need to identify a simple and cost-effective treatment for respiratory muscles weakness to prevent respiratory complications after SCI, improve quality of life and reduce the burden on the healthcare system.

Our primary aim is to determine definitively the effectiveness of training on respiratory muscle strength, respiratory physiology and health outcomes. To do this we will conduct a randomised controlled trial 2 times bigger than the largest previous study, of respiratory muscle resistive load training in individuals with acute and chronic cervical SCI. The project will provide critical new knowledge about the efficacy of a simple and inexpensive respiratory muscle training regime, which can be applied immediately in the hospital and community, to minimise respiratory morbidity in people with SCI. This project also provides a unique opportunity to investigate other consequential effects of long-term respiratory muscle training that have never been studied in people with SCI. These include effects on cough efficacy, sleep-disordered breathing, breathlessness, respiratory morbidity, respiratory health and neural drive to the diaphragm, as well as quality of life.

Obstructive Sleep Apnoea Imaging

We have developed novel imaging methods to measure the stiffness and movement of the upper airway muscles, and are using these together with measures of pharyngeal sensation, and electromyography to determine the patient-specific causes of obstructive sleep apnoea. We aim to use this information to tailor treatments for patients. One such treatment is a mandibular advancement splint, but currently it’s not possible to predict who will benefit from use a splint. We have a major project that aims to predict splint treatment outcome, based on our novel imaging methods.• Honours and PhD projects are available to study the neural, biomechanical and physiological aspects of obstructive sleep apnoea, including computational modelling

Determining new targets and approaches for treating sleep apnoea

We are running a range of projects to determine how existing treatments for sleep apnoea work so that we can optimise therapy and improve treatment success.

NeuroSleep: A NHMRC Centre for Research Excellence

This project aims to understand the bidirectional relationship between sleep and the brain to test and develop new approaches to treatment for sleep disruption across a range of medical disorders.  

Defining the Causes and Developing New Treatments for People with Spinal Cord Injury and Sleep Apnoe

The prevalence of sleep apnoea in people with chronic quadriplegia is two to seven times higher than the general population. Optimal treatment approaches may also differ.

Upper-Airway Reflexes and Muscle Control

We are conducting research to understand how important reflexes in the upper airway function to gain insight into the causes of obstructive sleep apnoea.

Effect of Morphine on Obstructive Sleep Apnoea

The goal of this project is to investigate the effects of opioids on upper airway muscle activity, respiratory control, and breathing during sleep in patients with obstructive sleep apnoea.

Sedatives and Sleep Apnoea

We are conducting several studies to examine the effects of common sleeping pills on the upper airway muscles and breathing during sleep.

Control of the neural drive to human breathing muscles in disorders such as obstructive sleep apnoea

We are looking at how changes in muscle architecture and mechanics relate to the neural drive to the muscle and whether that relationship is maintained in people with sleep apnoea.

Novel brain biomarkers of neurobehavioural dysfunction in obstructive sleep apnoea

This study aims to investigate the relationship between brain biomarkers measured at baseline, with neurobehavioural dysfunction during a subsequent extended wakefulness “load” that will uncover the individual variation in neurobehavioral dysfunction in patients with obstructive sleep apnoea.

Identifying cortical and subcortical sites involved in the control of blood pressure in health and disease

This NHMRC-funded project aims to identify areas of the brain involved in the control of blood pressure. We are currently extending an approach to studying the changes in the brain in renovascular hypertension, following patients with high blood pressure before and after renal angioplasty or stenting of the renal artery and normalisation of the high blood pressure.

What else is happening in Sleep apnoea research at NeuRA?

FEEL THE BUZZ IN THE AIR? US TOO.