Shallow sleep breathing in PWS may raise lung disease risk
Study recommends routine screening to catch pulmonary hypertension early
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Children with Prader-Willi syndrome (PWS) who experience abnormally slow or shallow breathing during sleep may face an increased risk of developing pulmonary hypertension, according to a U.S. study.
The findings suggest that sleep-related hypoventilation — a condition in which breathing is inadequate to remove carbon dioxide — is linked to pulmonary hypertension, which is characterized by high pressure in the blood vessels that supply the lungs.
The study examined 37 children with PWS who had available heart and sleep data. Overall, more than a quarter were diagnosed with pulmonary hypertension. All of the affected children had sleep-related breathing disorders, and half experienced hypoventilation.
“Our findings advocate for earlier and routine screening of PH [pulmonary hypertension], particularly in those with hypoventilation,” researchers wrote.
The study, “Prevalence of pulmonary hypertension in children with Prader-Willi Syndrome,” was published in Sleep Medicine.
Routine screening for pulmonary hypertension
PWS is often linked to breathing problems during sleep. These breathing problems include obstructive sleep apnea, in which the airways repeatedly become blocked, and sleep-related hypoventilation, causing carbon dioxide to build up.
Pulmonary hypertension is a recognized, severe complication of sleep-related breathing disorders. It carries a higher risk of illness and death.
“Early identification of PH is crucial to initiating early treatment and in reducing the progression of disease and symptom burden,” the researchers noted.
In the study, a team of researchers in the U.S. set out to investigate the frequency of pulmonary hypertension in children with PWS and sleep-related breathing disorders, and their associated risk factors.
“We hypothesized that obesity and presence of hypoventilation and obstructive sleep apnea predisposed patients with PWS to develop PH,” they wrote.
The team retrospectively reviewed records for 235 children at Children’s Hospital Los Angeles. Only 37 had interpretable data from an echocardiogram — an ultrasound that produces heart images and can help identify pulmonary hypertension — alongside a sleep study or a diagnosis of chronic respiratory failure (low oxygen and high carbon dioxide).
Ten (27%) of those 37 children — seven boys and three girls — were diagnosed with pulmonary hypertension at an average age of 11.1 years. All 10 were severely obese and had sleep-related breathing problems.
All but one of these 10 children with pulmonary hypertension had data from at least one sleep study, which showed that five had severe obstructive sleep apnea. Three others had mild, while one had moderate obstructive sleep apnea.
Their average obstructive apnea-hypopnea index, which measures how many times breathing is blocked or reduced per hour of sleep, was 21.9 (range of 3-101 events/hour).
Five children with pulmonary hypertension had sleep-related hypoventilation. In four, breathing was inadequate throughout the entire sleep period. One additional patient did not undergo a sleep study but had chronic respiratory failure.
Nine of the 10 children with pulmonary hypertension had already been prescribed noninvasive or invasive breathing support during sleep before their echocardiogram. Pulmonary hypertension was still diagnosed in eight of these children despite this treatment, suggesting that breathing support may not always prevent the lung disease.
Challenges in diagnosing pulmonary hypertension
Echocardiograms did not always clearly identify pulmonary hypertension. Some children had an increased blood flow through a heart valve, which can suggest high pressure in the lungs. Others had signs such as flattening of the heart wall between the lower chambers or enlargement of the right lower chamber, which pumps blood to the lungs.
One child underwent cardiac catheterization, an invasive procedure that directly measures pressure inside the heart and blood vessels. This confirmed pulmonary hypertension, even though their echocardiogram did not show indirect signs of it. This finding suggests that echocardiography can sometimes miss pulmonary hypertension and that cardiac catheterization may be considered when there is strong clinical suspicion.
Finally, statistical analyses showed that sleep-related hypoventilation, but not obesity or obstructive sleep apnea, was significantly associated with pulmonary hypertension.
“In summary, we found a detectable association between pulmonary hypertension and hypoventilation in patients with PWS,” the researchers concluded. Because echocardiograms may be difficult to interpret or may miss pulmonary hypertension, additional testing, including cardiac catheterization, may sometimes be necessary, they noted.
Still, “larger studies are needed to study the risk factors for PH in patients with PWS and determine the timing and frequency of screening for PH in this population,” the team concluded.
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