Hidden Barriers in Bariatric Surgery

This report from the European Respiratory Society highlights two important problems in the way the media and bariatric researchers are framing the discussion about post-operative sleep breathing changes following significant weight loss. First and foremost, they only report the AHI, the apnea-hypopnea index, and not the RDI, the Respiratory Disturbance Index. Thus, it is safe to assume that the researchers did not use advanced respiratory technology to measure UARS events (a.k.a. flow limitation events), the subtle breathing patterns that also provoke sleep fragmentation and subsequent daytime impairment in ways quite similar to classic sleep apnea. The second issue is the comment that the surgical intervention reduced or eliminated snoring in some patients, as if to suggest that snoring is a reliable marker of sleep breathing problems.

In sum, we are faced with the dilemma that both the media and the bariatric researchers are accepting outdated metrics for assessing sleep-disordered breathing (SDB). In the first instance, the assumption is that the AHI tells the whole story. It’s wonderful news to hear that AHI drops post-weight loss, but by not defining and measuring the RDI, it is safe to assume that many of these patients still suffer from SDB that likely needs treatment. The commentary on snoring represents another outdated metric in that we know many patients don’t snore and have SDB, and there are some who do snore and don’t have SDB. Bottom line is that snoring doesn’t tell us a lot about someone’s SDB condition. Again, it’s wonderful news that snoring decreases or disappears with post-op weight loss, and it likely signals that SDB severity has decreased, but it doesn’t tell us whether or not the patient still suffers from SDB, and that is the most important issue in question about the patient’s sleep health.

Imagine if the heart surgeon told a patient, “Looks like we’ve cut down your coronary blockages by 50%.” No intelligent heart patient would be satisfied with such a claim. “Okay, but how much coronary blockage do I still have left?” Same goes for SDB, “how much SDB do these patients still suffer from?” is the question at hand.