Posted by Joepie on August 26, 2008 at 14:33:37:In Reply to: My Undiagnosed OSA - I found posted by pgrovetom on August 23, 2008 at 14:15:20:
A quote from an article I found for your reference:
"Oximetry alone is often touted as a good way of screening patients for OSA. However, oximetry has the following limitations:it can fail to diagnose patients who have few apneas but who are very symptomatic,
it can fail to diagnose patients who have apneas lasting only 10 -15 seconds,
it will fail to diagnose patients who have frequent hypopneas which are not associated with oxygen desaturation,
it does not indicate whether the drop in oxygen is due to a central or obstructive apnea,
it does not provide other useful information such as body position and limb activity.
Not all oximeters are created equal. The oximeters which are commonly in use for screening for OSA use sampling intervals of 10 - 15 seconds. However, these long sampling intervals make the devices insensitive for the detection of brief apneas. The minimum acceptable sampling interval for oximeters used for this purpose should be 5 - 6 seconds. Most multiparameter home monitoring devices use oximeters with sampling intervals of 2 - 3 seconds.It may be more difficult to determine whether changes in oxygen saturation are real or due to artifact when you are recording only the oxygen signal. Trying to make oximetry more sensitive by using a drop in oxygen saturation of 2 % as the criteria for detecting an abnormal event increases the chance of interference from movement artifacts."