Though many obese patients exhibit symptoms of asthma or sleep apnea — wheezing, shortness of breath, daytime sleepiness — those conditions could be masking another condition altogether.
In fact, two other conditions — obesity hypoventilation and dyspnea — might be to blame for respiratory insufficiency.
Obesity hypoventilation, defined as shallow breathing or under breathing, is associated with increased or excessive weight on the chest or abdominal area. The fatty tissue pushes against the diaphragm reducing lung capacity and impeding the movement of the diaphragm.
“Gradually you take breaths that are shallower and shallower and then you get to the place were you don’t really exchange air very well,” says Mary Vernon, M.D., FAAFP, CMD, president of the American Society of Bariatric Physicians. “Then you have what’s called hypoventilation, and you start keeping carbon dioxide in your body. Then you get sleepy and then you can actually end up completely going to sleep and dying from that.” The disorder is called Pickwickian syndrome.
“It’s like a slow, suffocating feeling. That patient doesn’t have the capacity to expand the lungs, nor a strong ability to contract and relax the diaphragm,” says ResMed’s Ann Tisthammer.
Generally, these patients need non-invasive ventilation to keep the upper airway open. A bi-level device maintains expiratory pressure while offering pressure support for a more adequate breath, says Tisthammer.
Respironics’ Sharon Baer agrees that bi-level devices offer relief for those with obesity hypoventilation. Such a device “will deliver to the patient not only a specific pressure that’s going to help them achieve a larger title volume, but it will also provide them a set respiratory rate to help the patient maintain a certain level of stability when they go into REM and maybe parts of their respiratory anatomy stop functioning because of paralysis,” she says.
Couple that bi-level technology with an auto algorithm and the patient would get appropriate volume levels when need fluctuates, says Baer. Respironics plans to introduce such a device, called an AVAP, by the end of the year to meet this demand.
Wheezing and shortness of breath caused by dyspnea also may be misdiagnosed as asthma. Obesity increases the work of breathing because the chest wall is heavier. Essentially, it takes more effort to breath, resulting in more shallow, rapid breaths. Dyspnea may also be the result of lung or heart problems.
“(These patients are) labeled as (having) asthma when really they don’t have asthma, and they just have obesity causing symptoms that sound like asthma,” says David A. Beuther, M.D., assistant professor in the Department of Medicine at National Jewish Medical and Research Center, University of Colorado at Denver and Health Sciences Center. “Obesity can confuse the diagnosis, and in order to establish a diagnosis, you need to do a little more testing than you might for a thin person.”
To differentiate asthma from dyspnea, Beuther recommends spirometry or bronchial challenge testing.
Certainly, patients might demonstrate symptoms of multiple syndromes as well.
“It does get interesting when you’ve got people with multiple disease states to deal with,” agrees Jezerc. As a result, manufacturers, such as Respironics, are ramping up educational efforts to ensure providers and therapists know what device is appropriate to treat a client’s specific disease state.
