Archief Roodbont

Hi, I'm Dr. Henry Black. I'm Clinical Professor of Internal Medicine at the New York University School of Medicine, Immediate Past President of the American Society of Hypertension, and a member of the Center for the Prevention of Cardiovascular Disease at New York University. Today I want to talk about obstructive sleep apnea. This is an issue that has become more and more important as we realized how common it is and how it complicates a lot of our antihypertensive therapy, especially with resistant hypertension where we pile on drugs and don't seem to get to goal.

Some estimate that 70%-83% of people with resistant hypertension have obstructive sleep apnea as defined by the apnea-hypopnea index -- generally over 5, but usually much more than that. It is defined as apnea for at least 10 seconds with no flow or hypopnea for 10 seconds with reduced flow, with a reduced oxygen saturation of about 3%. This has been associated with obesity, but not everybody with sleep apnea is obese. You can usually figure it out clinically when people report snoring or daytime sleepiness. This seems to be a much more common issue than we realized, and it's likely to get even more common as we go along.

The treatments for obstructive sleep apnea are disappointing. The thing that seems to work best at lowering blood pressure is continuous positive airway pressure (CPAP). Many patients, even with the newer machines that are much easier to use, have trouble tolerating CPAP even though they feel better when they do it. They're not sleepy all day and don't snore as much, but you have to lie on your back, and not everybody can sleep that way. Is this really good for blood pressure? This was recently studied in a Spanish study^[1] of about 35 people who got conventional therapy and 35 who got CPAP. The study lasted 3 months. Ambulatory blood pressure monitoring (ABPM) was done at the beginning and at the end. What you get is a sense of a dose response, because you look at how many hours the CPAP was used and what the results were in the apnea-hypopnea index.

Like any therapy, not everybody can tolerate it. Only 20 of the 29 people who were in the CPAP group were able to complete the study. The comparison group received conventional therapy. These were truly resistant hypertensive patients. Most were on 3 drugs, some were on 4, some were on 5, and they weren't at goal blood pressure. We can accept that as an appropriate cohort. About 37 people were randomized to conventional therapy with no sham-CPAP. Some of us would say that if you don't put something on, maybe it's not really a control group. Of those who were randomized to CPAP (originally 37), 9 of them wouldn't even accept it or couldn't tolerate it, and there was 1 that was lost to follow-up. Of the 29 people who were in the CPAP group, 20 were bona fide resistant hypertensive patients when you used ambulatory monitoring. The other 9 weren't.

At the end of 3 months, they repeated the ABPM study and found something quite interesting. Overall, there really was no benefit in blood pressure to CPAP unless you used it long enough. The median time of CPAP use was about 5.5 hours. Those who were above the median had a substantial drop in blood pressure, both on ABPM and in the office, but those who didn't use it as much did not. Like any drug, there's a dose response. There are adverse reactions, but this looks like a potentially promising therapy for resistant hypertension, although by no means is this the definite answer. We have to look further into this and maybe try to develop some better therapies. The best is probably to try to prevent the obesity that is so often related to obstructive sleep apnea. Thank you very much.

# posted by roodbont @ 2:35 AM