Colorado doctors look to expand research on high altitude pulmonary edema in mountain residents and children
August 23, 2018
Colorado doctors are leading the charge to promote expanded research into high altitude illnesses, namely high altitude pulmonary edema (HAPE), in an attempt to remove barriers in understanding the disease and how to combat it. Dr. Deborah Liptzin was in Summit on Tuesday to present her research on the subject at the Ebert Family Clinic in Frisco.
The issue for doctors exploring the illness is a lack of existing research in the field, especially in cases involving children.
"Areas of research that are well funded are areas where there are either lots of patients or lots of potential for pharmaceuticals companies," said Liptzin, assistant professor of pediatrics at Children's Hospital Colorado. "So high cholesterol medications have a huge populations they can treat, whereas kids at high altitude is an extremely small population. Colorado is one of the only places in the country you have kids living at high elevations."
According to a study published by Dr. Christine Ebert-Santos of Ebert Family Clinic in 2017, the population in Colorado's counties above about 9,186 feet has grown from 21,000 in 1980 to 52,000 in 2010. This helps to explain both the lack of research in the area and an increase in HAPE cases in adults and children.
There are three different ways that children or adults can develop HAPE: by traveling from low altitude locations to high altitude locations (classic HAPE), returning to a high altitude home after traveling to low altitudes (re-entry HAPE), or developing HAPE without any change in elevation (high altitude resident pulmonary edema, or HARPE). Children may be more susceptible to HAPE due to increased vascular reactivity, immature control of breathing and increased frequency of respiratory illness.
While most cases of HAPE are relatively easy to treat — necessitating a change in elevation, oxygen and in some cases medication — failure to act can be fatal. Also troubling is that doctors who haven't dealt with it before, especially HARPE, may not be looking for it, and children are often misdiagnosed with asthma or pneumonia.
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"If you're not familiar with something, you won't think of it," said Ebert-Santos. "If the only tool you have is a hammer, everything is a nail. So everyone gets treated for pneumonia or asthma."
But Ebert-Santos, who has been working at altitude for 19 years, knows better. Her clinic saw more than 4,000 patient visits in 2015, with 48 child patients meeting the selection criteria for her study, "High-Altitude Pulmonary Edema in Mountain Community Residents," an exploration of HARPE — or what Ebert-Santos called mountain resident HAPE. Of those 48 children exhibiting symptoms — oxygen saturation and respiratory symptoms, among others — 69 percent were determined to have HARPE, 10 percent had re-entry HAPE, 4 percent had classic HAPE and the others were diagnosed with pneumonia (13 percent) and acute asthma exacerbation (4 percent).
Liptzin's research helps to shed some light on the illness. Liptzin recently performed a retrospective study on hundreds of Children's Hospital patients from 2004–14, identifying several with a form of HAPE. The study revealed that the illness appears to be more common in spring and winter than summer and fall, presumably matching up to more popular traveling times. But perhaps most perplexing to doctors is that post-pubertal men appear to be considerably more vulnerable than women. Liptzin's study aligns closely with Ebert-Santos' research, wherein 73 percent of patients were men.
"One of the biggest questions is why males seem to suffer more from HAPE than females," said Liptzin. "We think it's post pubertal, something that happens in puberty. But whether female is protective, or male is a risk factor we don't know."
Studies also show that kids with a history of HAPE saw significant increases in pulmonary artery pressures, and that they were more likely to experience the illness again. Children with Down syndrome are also at an increased risk due to heightened risk factors like pulmonary vascular reactivity and a prevalence of congenital heart disease.
But all children dealing with HAPE likely warrant evaluation for underlying issues like cardiac disease and pulmonary hypertension.
"We are concerned because acute HAPE can be fatal," said Ebert-Santos. "But the secondary concern is we know that everyone with HAPE has high pulmonary pressures. People with high pulmonary pressures, even without HAPE, are going to have limits in their pulmonary function years down the road. Most of what we see is reversible. But the studies are so small that we don't really know."
That's the crux of the issue. With incredibly small sample sizes and relatively small research funding, doctors studying HAPE have very little evidence to support recommendations for prevention and treatment.
"There's a research pyramid based on evidence, and the weakest thing we can do is lean on expert opinion," said Liptzin. "I think the biggest message is that more research needs to be done. HAPE can be fatal, so recognizing the symptoms and acting accordingly is important. Many can be treated without even a change in elevation. I think education is also important. Talking to doctors, publishing more articles and going to more meetings and conferences can make a difference."
"What we need is more corroboration with mountain physicians and those who see patients in the mountains," added Ebert-Santos. "That would really help us move this research ahead more quickly."