Wednesday, April 22, 2015

Obstructive sleep apnea and tooth wear

In my practice, I see lots of patients with excessive tooth wear, or irreversible loss of the tops of the teeth. It gets more common with age. It's not always due to teeth grinding - it can occur from eating certain foods, especially those high in acidity. This study looked at the association between tooth wear and obstructive sleep apnea (OSA). This was a study done in a private dental clinic in Spain, and patients diagnosed with tooth wear each had an overnight home sleep study to assess for OSA. The results showed that the prevalence of OSA was three times higher in patients with tooth wear. And there was a positive correlation between OSA severity and tooth wear, meaning the more severe the OSA, the more severe the tooth wear. The relationship was not diminished after controlling for body mass index, age, and gender.

The study authors speculated that there could be a common mechanism behind the OSA and tooth wear, such as arousal from sleep contributing to tooth clenching or grinding. The study authors also pointed out that the association between OSA and tooth wear could be coincidental, as both conditions become more prevalent with advancing age.

Finally, the study authors recommended that dentists consider referring patients with tooth wear to their primary care provider or sleep doctor for evaluation of possible OSA.

Wednesday, April 15, 2015

Sleep apnea and high blood pressure

Another post about obstructive sleep apnea (OSA) and high blood pressure (HTN). This study is a meta-analysis of observational studies and randomized controlled clinical trials. The study authors studied patients with resistant HTN, meaning blood pressure that was not responding to multiple medications. The study participants also had OSA.

I don't have access to full article, only the link above and the abstract. The results suggest that those patients with the highest blood pressures had the greatest reduction in blood pressure after using CPAP therapy. The study authors concluded that untreated OSA may be why some patients' blood pressure just won't come down with multiple medications.

The results from this study are not new, but do provide more evidence of the importance of screening patients with resistant HTN for underlying OSA. In my community, primary care doctors have been doing this for years already. However, this may not be the case in other medical communities around the country.

Wednesday, April 8, 2015

Blood pressure and sleep apnea

Several research studies have linked high blood pressure (HTN) to obstructive sleep apnea (OSA). The etiology is not clear, however. With OSA, there is sleep disturbance from brief awakenings, thought secondary to adrenaline release that is triggered when breathing resumes. Also, oxygen level reductions, called desaturations, could lead to elevated blood pressures. Respiratory events that are detected during a sleep study have specific scoring criteria - the event has to last at least 10 seconds and result in either a brief arousal from sleep and / or an oxygen desaturation.

This study sought to determine which types of respiratory events were most likely to result in HTN. The researchers followed 2040 participants and used sophisticated statistical models to study the sleep study results and blood pressure measurements. Results showed that those respiratory events with at least a 4% oxygen desaturation were most consistently associated with HTN. Interestingly, the other sleep study measurement that correlated with HTN was periodic limb movements that resulted in brief arousals from sleep.

Wednesday, April 1, 2015

CPAP use after weight-loss surgery

Obstructive sleep apnea (OSA) and obesity are related. Weight loss can improve OSA, sometimes enough to eliminate it altogether. However, if OSA is severe, weight loss alone is often not enough to cure OSA.

Most patients who undergo weight loss surgery have OSA, and most use CPAP prior to weight loss surgery. Unfortunately, most patients discontinue their CPAP use after weight loss surgery. This study assessed long-term CPAP use in 21 patients who had undergone gastric banding. Results showed that body-mass index significantly increased by 6.8 in those patients who did not use their CPAP after weight loss surgery. And BMI dropped by 1.8 in those patients that were adherent to CPAP therapy after weight loss surgery.

Another important point is that OSA persisted in almost all of the patients who underwent the surgery, despite the substantial weight loss (average 121 pounds lost). And, after 7.2 years of follow up, the majority of patients had gained back some weight (22 pounds).

So the data in this study suggest that CPAP adherence for the long term may help with weight loss maintenance. Remember this is a small study though. Other confounding factors could contribute to reasons why some patients chose to keep using CPAP. For instance, some may have continued only because using CPAP made them sleep better or have more energy. And that increased energy could have helped them keep exercising, which may help maintain weight. Or those that kept using CPAP may have adhered better to diet restrictions.

In the end, follow up with the sleep medicine specialist is important after weight loss surgery. In that way, post-operative OSA severity can be assessed after the first year. Then, the patient and sleep medicine physician can discuss the pros and cons of continuing CPAP therapy if necessary.