Bariatric Surgery and Sleep Apnea

Sleep apnea is a health condition that is closely tied with obesity and causes one or more pauses in breathing or shallow breaths during sleep. These disruptions result in poor sleep quality and can cause extreme tiredness during the day. At the Obesity Society’s national meeting this month, new research was presented that found that patients with obesity and type 2 diabetes participating in a sleep sub-study lost significantly more weight with an intensive lifestyle intervention program than those in the control group and also significantly reduced their apnea-hypopnea index or AHI (an index used to assess the severity of sleep apnea).

Through four years of the study, the patients undergoing the intensive intervention maintained about a four-point reduction in apnea-hypopnea index, compared with a sustained four-point increase in the control group. While the change in apnea-hypopnea index was significantly correlated to the weight change, there was still a significant decrease in symptoms even after the change in weight was accounted for, indicating that the intervention had an impact on obstructive sleep apnea that was separate from the weight loss.

Another interesting study was recently conducted by researchers at the University of South Florida at Tampa and reviewed in the journal Chest Physicians. The study linked bariatric surgery deaths to undiagnosed and untreated sleep apnea. The researchers found that severe prolonged and frequent hypoxemia (low blood oxygen pressure) is common in sleeping weight loss surgery patients and they set out to  figure out why such patients, who were otherwise recovering well after surgery, died suddenly in their sleep. The study looked at 15 gastric bypass patients who were monitored for 24 hours after surgery.  The patients had an average episode of hypoxemia that lasted 21 minutes and the longest went on for hours.  Also of note, blood oxygen saturation fell as low as 60 percent during the observation.

Dr. Scott Gallagher, a bariatric surgeon at the University of South Florida, commented that the causes of hypoxemia were due to either postoperative, narcotic induced hypoventilation or obstructive sleep apnea.  All of the participants had prolonged episodes of hypoxemia, which could not be explained entirely by hypoventilation in any of the patients.  The mild hypoventilation was not clinically significant, leaving only sleep apnea as the most likely cause of hypoxemia after weight loss surgery.  Dr. Gallagher believes that once a bariatric patient desaturates, the mild narcotic induced hypoventilation pushes a few of these patients over the edge and death can result.  Dr. Gallagher recommends routine postoperative monitoring of bariatric surgery patients.  Patients with diagnosed sleep apnea need to use their CPAP especially when receiving narcotic analgesics.

Dr. Helmuth Billy, Director of Bariatric Surgery at St. John’s Regional Medical Center and owner of Dr. Billy Bariatrics, commented that “the study has potential implications for bariatric surgery patients and suggests that monitoring should be more aggressive postoperatively and preoperative evaluation of sleep apnea needs to be more widespread.  Because there is no reliable way to screen for sleep apnea without utilizing a sleep study and overnight polysomnogram , physicians should consider establishing a standard of care including formal sleep apnea screening for all patients,” he concluded.

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