Posted by Kevin (in Walla Walla) on June 04, 2004 at 10:09:34:

In Reply to: UARS -- easily detected / treated? posted by Sleepy Time Time on June 03, 2004 at 20:02:36:

The term Sleep Disordered Breathing includes the whole spectrum from snoring to UARS to hypopneas to apneas. I tend to split things into the central event family and the obstructive event family. True central apnea is fairly rare. It is a result of either a neurological injury or disease, or a cardio-pulmonary disorder like Congestive Heart Failure. Other times central events occur during CPAP adaptation and this is a result of changes in the bloods acid/base balance in response to you finally breathing again. Many times central events are actually obstructive in nature and just don't show up as obstructive on some PSG recording system.

UARS can be diagnosed in a couple different ways. The "gold standard" is to use esophageal pressure manometry. This involves inserting a thin tube or a ballon into the esophagus and measuring pressures. If you want, I can explain more, just let me know. Unfortunately, there are very few Sleep Centers set up for doing esophageal pressure. Other ways to look at UARS include using a nasal pressure transducer, or a system knows as respiratory inductance plyesmography. One looks at flattening of the inspiratory pressure curve and one can look at a representation of a flow volume loop.

Many times respiration will look fairly normal in a typically recorded sleep study, but there are frequent unexplained arousals. Personally, I think these arousals are a result of the subtle changes seen in UARS. If it was up to me (and unfortunately it isn't), I would classify all events just as abnormal respiratory events. They will all have pretty much the same results - frequent micro-arousals in the brain. It's these arousals, along with the chronic desaturations that result in the excessive daytime sleepiness, memory problems, concentration problems, etc.

Unfortunately, many Auto-titrators do a terrible job at recognizing and treating UARS, even though most manufacturers will tell you their system works great. All auto systems use propriatry algorhythms to analyse the breathing pattern. Each company sets up their algorhythm different according a "best fit" scenario. If your abnormal breathing pattern fits into their "curve", the machine will probably work for you. If it doesn't, you'll be up a creak. Unfortunately, there is no way to predict (as of now) who will work on what machine. I've had patients use 3 or 4 different auto systems and come up with 3 or 4 different pressures that weren't even close. I've tried them all on myself and come up with average mean pressures of anywhere from 4 cm to 16 cm. We're also used auto's on patients and then brought them into the lab for another titration. We rarely find the same pressure to be ideal as the auto's find.

Follow Ups:

• Re: UARS -- easily detected / treated? Sleepy Time Time 12:03 6/04/04 (4)
  • Re: UARS -- easily detected / treated? Kevin (in Walla Walla) 15:13 6/04/04 (3)
    • Re: UARS -- easily detected / treated? Sleepy Time Time 16:03 6/04/04 (2)
      • Re: UARS -- easily detected / treated? Jake 17:32 6/04/04 (1)
        • Re: UARS -- easily detected / treated? Sleepy Time Time 18:56 6/04/04 (0)

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