We spend around one-third of our lives sleeping. While we sleep, our brain enters different phases. We spend most of the night in what is known as the “slow wave sleep” phase where our brain waves slow, our muscles relax, and our breathing becomes deep and slow. This serves to restores us, clean waste from our brains, and supports our learning and memory.

For children born with the rare genetic disease familial dysautonomia – FD for short, sleeping may not be so simple or restorative. These patients have periods of interrupted breathing at night. They have apneas with long pauses in their breathing or can enter periods throughout the night when their breathing becomes too shallow.

These abnormal breathing patterns would usually trigger an arousal, prompting us to wake up, gasping from lack of oxygen and the build-up of carbon dioxide in blood. Only in children with FD, the brain doesn’t receive these arousal signals and sometimes the patient may not wake up at all.

“Children with FD have a much greater chance of dying unexpectedly during sleep,” explained Dr. Alberto Palma a neurologist and Assistant Director of the Dysautonomia Center. “This this is why we had an urgent need to understand which of our patients were at high risk.”

The findings show that the risks of sudden unexpected death during sleep in patients with FD are one of the highest reported in any disorder

– Palma et al., 2017 Sleep.

Dr. Palma and the investigators at the Center embarked on a project to understand sudden unexpected death during sleep in people with FD. The results were published recently in the medical journal Sleep and have shed light on the link between apnea and a higher risk of sleep death in patients with FD.

The team compared patients that had died unexpectedly during sleep and matched cases that remained alive. They looked at the results of their sleep studies and clinical records, trawled through coroner’s office reports, and conducted formal interviews with the bereaved relatives. They found that patients that were treated with high dose fludrocortisone, had lower levels of potassium in blood, and those who had untreated obstructive sleep apnea were at the highest risk of dying during sleep.

Sleep apnea is treatable and the use of non-invasive ventilation reduces the risk of sudden unexpected death during sleep in patients with FD. – Dr. Horacio Kaufmann

The results make a lot of sense, as Dr. Palma explained, “low potassium (or hypokalemia) is a known risk factor for life-threatening arrhythmias and sudden cardiac death and hypokalemia is a frequent side effect of treatment with fludrocortisone”.

The findings from the study have direct implications for patient care. First, the medical team no longer recommends high doses of fludrocortisone. Second, sleep apnea is treatable and the use of non-invasive ventilation reduces the risk of sudden unexpected death during sleep in patients with FD. This makes it all the more important to identify sleep apnea and start treating it as soon as possible. The team now recommends that all patients have an annual in-hospital sleep study to screen for sleep disordered breathing. When found, it should be treated.

In recent years, sleep technology has advanced. Patients with sleep apnea can be fitted with special masks to wear at night. These apply pressure to the airways to prevent them from collapsing, keeping the airway open, and enabling the breath to move in and out while sleeping. While it may be difficult at first for a person to get used to sleeping with a CPAP or BiPAP mask, patients do eventually notice a difference. There are additional health benefits of treating sleep apnea. With better sleep you are less tired, more alert and it’s easier to concentrate during the day.

The take home message from the study is that the risks of sudden unexpected death during sleep in patients with FD are one of the highest reported in any disorder. But, we have now found ways to reduce those risks and what matters is to be proactive.

 

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The findings of the article were published in the journal Sleep:

Palma JA, Norcliffe-Kaufmann L, Perez MA, Spalink CL, Kaufmann H. Sudden Unexpected Death During Sleep in Familial Dysautonomia: A Case-Control Study. Sleep. 2017 Aug 1;40(8). doi: 10.1093/sleep/zsx083.

Read Michael’s story on how he got used to sleeping with BiPAP: here