Pulmonology and Sleep Medicine News

child sleeping

Losing sleep: Severe obstructive sleep apnea

child sleeping

Researchers at Children’s National collected information on 250 children with severe obstructive sleep apnea – defined as at least 10 pauses in breathing in an hour during sleep – who were seen at Children’s National’s Pediatric Sleep Laboratory.

Obstructive sleep apnea (OSA) often starts with a snore that sounds harmless enough. But over time, explains Sasikumar Kilaikode, M.D., a pediatric pulmonary fellow in the Division of Pulmonary Care at Children’s National Health System, this condition can lead to serious health consequences. OSA, caused when the airway becomes periodically blocked during sleep, has a bevy of associated and often serious complications that can affect children, including heart problems and neurocognitive issues, such as learning disabilities.

“Many of the consequences of obstructive sleep apnea are preventable if patients get timely diagnosis and treatment,” Dr. Kilaikode says. “But we haven’t been sure how timely these interventions happen for some of our patients.”

Researchers have reported that conditions such as asthma and probably OSA tend to disproportionally affect children from disadvantaged backgrounds and that the severity of this condition tends to be greater in minority groups. However, Dr. Kilaikode explains, there have been insufficient data about how the most severe form of this condition affects inner city residents, a population that tends to have relatively higher numbers of disadvantaged, minority children – particularly the timeliness of diagnosis and treatment for this group.

To investigate, Dr. Kilaikode, his mentor Gustavo Nino Barrera, M.D., and colleagues collected information on 250 children with severe OSA – defined as at least 10 pauses in breathing in an hour during sleep – who were seen at Children’s National’s Pediatric Sleep Laboratory. This facility performs sleep studies on children during which their oxygen levels, breathing patterns, movements and brain activity are monitored while they snooze in a hospital bed overnight.

Besides their sleep study data, the researchers also collected information about:

  • Risk factors for OSA (such as enlarged tonsils or adenoids, craniofacial abnormalities, asthma, prematurity or obesity)
  • Demographics
  • Duration of symptoms before diagnosis by the overnight sleep study

The vast majority of the 250 children enrolled in the study were African American, reflective of the demographics of the hospital’s service area. The team was surprised to learn that the time to diagnosis for African American study participants was much longer than the time to diagnosis for the non-Latino white study participants.

The team presented these results at the American Thoracic Society 2017 International Conference in Washington, D.C.

“The longer patients take to get diagnosed and treated,” Dr. Kilaikode notes, “the more likely the serious consequences of OSA become permanent.”

He adds that it’s unclear why it took so long for some patients to be diagnosed – the team’s current research efforts are focused on this question. Some of their theories are that families and schools might be unaware of this condition and its symptoms; some families might have limited access to the health care system; probable lack of screening by primary care providers; or problems with health insurance might preclude timely or adequate care.

In the future, he and other members of the Children’s pulmonary team would like to focus OSA education and outreach efforts on people that this study suggests have the greatest need: Minority and low-income families. The first step, Dr. Kilaikode says, is helping families recognize symptoms early.

Symptoms of obstructive sleep apnea include:

  • Snoring
  • Choking, gasping or prolonged pauses in breaths during sleep
  • Daytime fatigue and/or sleepiness
  • Learning problems or difficulty concentrating at school
Chinwe Unegbu

PDE-5 inhibitors for pediatric hypertension

Chinwe Unegbu

A study led by Chinwe Unegbu, M.D., indicates the benefits of PDE-5 inhibitors to treat pediatric pulmonary hypertension far outweigh potential harmful side effects.

Pulmonary hypertension (PH), when pressure in the blood vessels leading from the heart to the lungs is too high, is primarily a disease of adults: Patient registries suggest that the mean age of diagnosis is around age 50. However, more and more children are developing this condition, says Chinwe Unegbu, M.D., an assistant professor in the Division of Anesthesiology, Pain and Perioperative Medicine at Children’s National Health System.

Although adults with PH have several different effective treatments, Dr. Unegbu adds, children have few options. One of these is a class of medications known as phosphodiesterase type 5 (PDE-5) inhibitors, which act on molecular pathways that can open up constricted blood vessels. However, some studies have raised questions about the safety of this class of medications, particularly with long-term use of high dosages.

In a new study, Dr. Unegbu and colleagues performed a systematic review of available literature on this class of drugs evaluating their effectiveness and safety for pediatric patients. The review showed that like all medications, PDE-5 inhibitors have some risks. However, Dr. Unegbu says, the review showed that their benefits, including improved echocardiography measurements, cardiac catheterization parameters and oxygenation, far outweigh potential harmful side effects.

“Pediatricians across the nation view the rise in pediatric PH cases with growing concern because the disease can worsen, leading to right ventricular failure and death,” says Dr. Unegbu, lead author of the study. “PH can occur in newborns, infants and children who have a number of health conditions, including congenital heart disease, the most common birth defect among newborns. There are few available treatments for the growing population of children affected by this condition, so it is heartening that the evidence supports PDE-5 inhibitors for patients with PH.”

Patients with PH experience increased pressure in the pulmonary arteries, which carry blood from the heart to the lungs where it picks up oxygen that is ferried throughout the body. According to the National Institutes of Health, this leads patients to suffer from shortness of breath while doing routine tasks, chest pain and a racing heartbeat. Changes to the arteries make it progressively harder for the heart to pump blood to the lungs, which forces the heart to work even harder. Despite the heart muscle compensating by growing larger, less blood ultimately flows from the right to the left side of the heart which can compromise the kidney, liver and other organs, Dr. Unegbu says.

The study team included four researchers from Johns Hopkins University: Corina Noje, M.D., John D. Coulson, M.D., Jodi B. Segal, M.D., M.P.H., and study senior author Lewis Romer, M.D. The researchers scoured Medline, Embase, SCOPUS and the Cochrane Central Register of Controlled Trials, looking for studies that examined PDE-5 inhibitor use by pediatric patients with primary and secondary PH. Their goals included describing the nature and scale of the pediatric PH, assessing available pharmacologic therapies and conducting the systematic review of clinical studies of PDE-5 inhibitors, a mainstay of PH therapy.

They identified 1,270 studies. Twenty-one met the criteria to be included in the comprehensive review, including eight randomized controlled trials – the gold standard. The remaining 13 were  observational studies in children ranging in age from extremely preterm to adolescence.

“Although there is some risk associated with PDE-5 inhibitor use by pediatric patients with PH, overwhelmingly the data indicate the benefits of using this class of drugs far outweigh the risks. When we looked at specific clinical outcomes, we see definite improvement in a number of measures including oxygenation, hemodynamics and better clinical outcomes: The patients are doing better, feeling better and their exercise capacity rises,” Dr. Unegbu says.

Because of lingering concerns about increased mortality, they also looked at toxicity data associated with this class of drugs. “With the exception of a single trial, the remaining trials included in our review did not demonstrate increased mortality in patients placed on this class of medicines, which was reassuring to us,” she says. Side effects ranged from mild to moderate, such as flushing and headaches. “We can say with a good degree of confidence that providers should feel fairly comfortable prescribing PDE-5 inhibitors.”

Ideally, researchers would like to have access to patient-specific measures that are a good fit for neonates and infants. Unlike adults, infants’ exercise capacity cannot be measured by their ability to climb stairs or use a treadmill. Another limitation, the study authors note, is the dearth of adequately powered clinical trials conducted in kids.

“Most of the studies have been conducted in adults. However, this disease unfolds in a much different fashion in children compared with adults,” Dr. Unegbu says. “We are desperately in need of high-quality studies in the form of randomized controlled trials in pediatric patients and studies that examine the full range of formulations of this class of drugs.”

Sarah B. Mulkey

Puzzling symptoms lead to collaboration

Sarah B. Mulkey, explaining the research

Sarah B. Mulkey, M.D., Ph.D., is lead author of a study that describes a brand-new syndrome that stems from mutations to KCNQ2, a genetic discovery that began with one patient’s unusual symptoms.

Unraveling one of the greatest mysteries of Sarah B. Mulkey’s research career started with a single child.

At the time, Mulkey, M.D., Ph.D., a fetal-neonatal neurologist in the Division of Fetal and Transitional Medicine at Children’s National Health System, was working at the University of Arkansas for Medical Sciences. Rounding one morning at the neonatal intensive care unit (NICU), she met a new patient: A newborn girl with an unusual set of symptoms. The baby was difficult to wake and rarely opened her eyes. Results from her electroencephalogram (EEG), a test of brain waves, showed a pattern typical of a severe brain disorder. She had an extreme startle response, jumping and twitching any time she was disturbed or touched, that was not related to seizures. She also had trouble breathing and required respiratory support.

Dr. Mulkey did not know what to make of her new patient: She was unlike any baby she had ever cared for before. “She didn’t fit anything I knew,” Dr. Mulkey remembers, “so I had to get to the bottom of what made this one child so different.”

Suspecting that her young patient’s symptoms stemmed from a genetic abnormality, Dr. Mulkey ran a targeted gene panel, a blood test that looks for known genetic mutations that might cause seizures or abnormal movements. The test had a hit: One of the baby’s genes, called KCNQ2, had a glitch. But the finding deepened the mystery even further. Other babies with a mutation in this specific gene have a distinctly different set of symptoms, including characteristic seizures that many patients eventually outgrow.

Dr. Mulkey knew that she needed to dig deeper, but she also knew that she could not do it alone. So, she reached out first to Boston Children’s Hospital Neurologist Philip Pearl, M.D., an expert on rare neurometabolic diseases, who in turn put her in touch with Maria Roberto Cilio, M.D., Ph.D., of the University of California, San Francisco and Edward Cooper, M.D., Ph.D., of Baylor College of Medicine. Drs. Cilio, Cooper and Pearl study KCNQ2 gene variants, which are responsible for causing seizures in newborns.

Typically, mutations in this gene cause a “loss of function,” causing the potassium channel to remain too closed to do its essential job properly. But the exact mutation that affected KCNQ2 in Dr. Mulkey’s patient was distinct from others reported in the literature. It must be doing something different, the doctors reasoned.

Indeed, a research colleague of Drs. Cooper, Cilio and Pearl in Italy — Maurizio Taglialatela, M.D., Ph.D., of the University of Naples Federico II and the University of Molise — had recently discovered in cell-based work that this particular mutation appeared to cause a “gain of function,” leaving the potassium channel in the brain too open.

Wondering whether other patients with this same type of mutation had the same unusual constellation of symptoms as hers, Dr. Mulkey and colleagues took advantage of a database that Dr. Cooper had started years earlier in which doctors who cared for patients with KCNQ2 mutations could record information about symptoms, lab tests and other clinical findings. They selected only those patients with the rare genetic mutation shared by her patient and a second rare KCNQ2 mutation also found to cause gain of function — a total of 10 patients out of the hundreds entered into the database. The researchers began contacting the doctors who had cared for these patients and, in some cases, the patients’ parents. They were scattered across the world, including Europe, Australia and the Middle East.

Dr. Mulkey and colleagues sent the doctors and families surveys, asking whether these patients had similar symptoms to her patient when they were newborns: What were their EEG results? How was their respiratory function? Did they have the same unusual startle response?

She is lead author of the study, published online Jan. 31, 2017 in Epilepsia, that revealed a brand-new syndrome that stems from specific mutations to KCNQ2. Unlike the vast majority of others with mutations in this gene, Dr. Mulkey and her international collaborators say, these gain-of-function mutations cause a distinctly different set of problems for patients.

Dr. Mulkey notes that with a growing focus on precision medicine, scientists and doctors are becoming increasingly aware that knowing about the specific mutation matters as much as identifying the defective gene. With the ability to test for more and more mutations, she says, researchers likely will discover more cases like this one: Symptoms that differ from those that usually strike when a gene is mutated because the particular mutation differs from the norm.

Such cases offer important opportunities for researchers to come together to share their collective expertise, she adds. “With such a rare diagnosis,” Dr. Mulkey says, “it’s important for physicians to reach out to others with knowledge in these areas around the world. We can learn much more collectively than by ourselves.”