New York, Sep 2 (IANS): An implanted nerve stimulator significantly improves symptoms in those with central sleep apnea, without causing serious side effects, show results from an international study.

Unlike the more common obstructive sleep apnea, in which the airway partially collapses and causes pauses in breathing, central sleep apnea (CSA) occurs when the brain fails to control breathing during sleep.

"Central sleep apnea is a serious concern because it affects about a third of people with heart failure and it's known to make the condition worse," said co-lead author William Abraham from the Ohio State University Wexner Medical Center in the US.

"Currently, we don't have good treatments available. Positive airway pressure devices have been used, but many patients don't tolerate them well and a recent study showed them to be harmful," Abraham noted.

The research team tested the safety and effectiveness of a transvenous phrenic nerve stimulator made by US-based Respicardia Inc at 31 hospitals in the US, Germany and Poland. 

Much like a pacemaker, it sends a regular signal telling the diaphragm to breathe during sleep.

In the randomised study, 151 patients were implanted with the device. 

Ten were excluded due to non-study related medical issues or deaths, exiting the study or missing visits. 

During the first six months of evaluation, 68 devices were activated for treatment, while 73 were left inactive as the control group. 

At the six month evaluation, the device reduced central sleep apnea events per hour by half or more for 35 of the 68 members (51 per cent) of the treatment group. 

Only eight (11 per cent) of those in the control group achieved the same reduction, reported the study published in the journal The Lancet. 

"Not only did we see this reduction in events per hour, the patients also rated themselves better on the Epworth Sleepiness Scale (meaning they were less sleepy during the day) and on a global assessment of their overall quality of life," Abraham said. 

"This tells us the effects of neurostimulation are clinically relevant and this could be a promising therapy for those with central sleep apnea," Abraham noted.