Preliminary Results Link GERD to Sleep Apnea

Charlene Laino

October 20, 2003

Oct. 20, 2003 (Baltimore) — Sleep disorders and gastroesophageal reflux disease (GERD) often go hand in hand; at least four fifths of the 60 million Americans who have been diagnosed with GERD say their symptoms worsen in the evening, often preventing them from sleeping peacefully through the night.

But the exact relationship between the two ailments, if any, has been the subject of much debate. Some researchers speculate that sleep apnea results in changes in intrathoracic pressure that cause acid reflux, while others say that esophageal acid exposure may cause reflexes connecting the esophagus and airways to interrupt breathing, inducing apneas.

Preliminary evidence that GERD may be the culprit, at least in nonapnea arousals, was presented here Wednesday by Brian P. Mulhall, MD, MPH, from the Gastroenterology Service at Walter Reed Army Medical Center in Washington, D.C., at the 68th annual scientific meeting of the American College of Gastroenterology.

But it's not just the acid, he said. Other liquids such as bile reflux may interrupt breathing and sleep.

"I must stress the preliminary nature of these findings," Dr. Mulhall told Medscape.

Eamonn Quigley, MD, from the Department of Medicine at Cork University Hospital in Ireland, agreed.

Also emphasizing the preliminary nature of the findings, Dr. Quigley said, "What they are suggesting is that GERD, in some way, and we don't know how yet, is affecting the control of respiration, leading to a drop in oxygen levels, which can lead to sleep apnea."

To date, Dr. Mulhall has studied 50 adults, 30 of whom had been diagnosed with sleep apnea, 10 of whom also suffered from nocturnal GERD.

The patients were monitored using either a traditional pH probe to measure acid reflux or with a multichannel intraluminal impedence (MII) catheter, which can detect and measure reflux of any type, not just acid reflux.

The MII catheter is better able to capture the nonacid reflux that might play a role in sleep apneas and arousals, Dr. Mulhall told Medscape.

The researchers monitored all the patients as they slept, tracking reflux incidents with both measures.

"Many patients with obstructive sleep apnea have no symptoms of heartburn," he said. "In the next phase of this study, we will be evaluating whether these patients are having more esophageal injuries than other people with reflux."

GERD events were measured and related temporally to apneas, hypopneas, and arousals. In addition, the researchers used questionnaires to measure baseline GERD symptoms and daytime somnolence.

Using a chi-squared test and intraclass correlation coefficients, the researchers found that a third of the patients with sleep apnea experienced "substantial" nighttime reflux.

If the preliminary results in the new report are borne out, MII may allow a better capture of nonacid GERD events that could play a role in respiratory events during polysomnography, Dr. Mulhall said.

"It may be the case that if you have obstructive sleep apnea, you need to be examined for reflux — even if you have no symptoms of GERD," he said. "MII may allow us to better capture both acid and nonacid GERD events that may play a role in the respiratory events that occur in these sleep disorders," he added.

Also, treating GERD may be an effective way to improve apnea-related sleep woes, Dr. Mulhall said. The next phase of his research will involve another 280 patients, who will also be evaluated with traditional pH probes or MII to measure all contents that flow into the esophagus, including nonacidic liquids that may produce fewer symptoms.

Those patients with GERD will eventually be randomized to receive either antireflux medication such as a proton pump inhibitor or placebo, as well as continuous positive airway pressure, to see if symptoms improve, he said.

The bottom line, Dr. Quigley said, "is these are very interesting findings, but further study is needed."

The study authors have disclosed having a financial relationship with AstraZeneca and Sandhill Scientific.

ACG 68th Annual Scientific Meeting: Abstract 594. Presented Oct. 15, 2003.

Reviewed by Gary D. Vogin, MD

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