In a study from The Hospital for Sick Children, the authors recommend that all infants with PWS be screened for sleep disordered breathing (SDB) and receive oxygen treatment as needed.
SDB is an area of great concern for the PWS community. SDB includes hypoventilation (shallow or too slow breathing), as well as sleep apnea. Sleep apnea is when breathing repeatedly stops and starts while sleeping.This leads to a lack of oxygen. There are two types of sleep apnea, obstructive and central. Most of us are more familiar with obstructive sleep apnea which is when tissue physically blocks airflow. This is often caused by soft tissue collapsing around the airway. Obesity and/or large adenoids contribute to obstructive apnea and snoring is a common indicator. Central sleep apnea, on the other hand, is when the brain doesn’t send the correct signals to trigger breathing during sleep. There are long pauses where someone basically “skips” breaths. People can have one type of sleep apnea, or in some cases, both at the same time.
Researchers are working to address several questions regarding SDB in PWS, including risk of sudden death, impact of growth hormone therapy, how and when to screen for SDB, and how clinical care should vary by age and type of SDB. Researchers at The Hospital for Sick Children in Toronto, Canada, recently published a report characterizing sleep disorders in their PWS patient population, specifically comparing infants and older children. Of note, all of the data used was collected from baseline sleep studies – those done before the start of growth hormone therapy. This allowed for direct comparison of differences by age, removing the variable of growth hormone treatment.
Looking at data from 44 patients (0-18 years; approximately half infants (under age 2) and half age 2-15), the main findings of the study are:
- Approximately 57% of PWS patients have some form of sleep disordered breathing prior to starting growth hormone therapy.
- Central sleep apnea is found more often in infants (43% of the infants) whereas older children (>2 yrs) are more likely to suffer from obstructive sleep apnea.
The obstructive sleep apnea finding is not surprising considering that older children also had a significantly higher incidence of obesity than infants, and obesity is a major cause of obstructive sleep apnea. But the authors did not expect such a high incidence of central sleep apnea in the infants, and the majority of the rest of the article focused on this issue.
The long term impact of central sleep apnea on infants is not entirely clear. However, obstructive sleep apnea and intermittent lack of oxygen have been associated with poorer cognitive development. Therefore, it would not be surprising if central sleep apnea has similar negative impacts on brain development. If that is the case, it is likely that early detection of the problem and appropriate treatment would have positive effects on brain development.
Importantly, providing low flow oxygen to infants was very effective in treating central sleep apnea in this study. It improved blood oxygen levels and reduced the average number of apnea events from 14 per hour to 1 per hour. This highlights the critical importance of screening PWS infants for central sleep apnea, and increasing the use of supplemental oxygen treatment for those with a diagnosis. In fact, the authors recommend that all infants with PWS be screened for sleep disordered breathing and receive oxygen treatment as needed.
For more information, please read the original research paper.