Interesting Findings......

But I think some folks here could have told them this and saved them some trouble.

Sleep apnea syndrome: improved detection of respiratory events and cortical arousals using oxymetry pulse wave amplitude during polysomnography.

Respiratory events (RE) during sleep induce cortical arousals (A) and marked changes in autonomic markers in sleep apnea syndrome (SAS). The aims of the study were double. First, we assessed whether pulse wave amplitude (PWA) added to polysomnography (PSG) could improve RE and A detection; second, we wanted to know whether the quality of detection of these two parameters could be improved using PWA. Respiratory disturbance index (RDI) and A were randomly scored twice by the same observer in 12 male patients with SAS. The first scoring was done using conventional PSG signals, the second scoring adding PWA to PSG. We also measured interobserver agreement by randomly selecting and reading 100 PSG sequences of 5 min with and without PWA by two observers. Adding PWA to PSG parameters allowed to detect significantly more RDI (53.9 +/- 21.6 h(-1) versus 48.3 +/- 22.3 h(-1), p < 0.001) and more A (68.0 +/- 14.4 versus 59.4 +/- 16.5, p < 0.001). Moreover, after using PWA, there was no significant disagreement between two observers for detecting RE, showing better quality of RE detection. PWA is a simple and cheap parameter that improves the diagnostic value of conventional PSG in sleep apnea syndrome by better detecting respiratory events and A.


http://www.ncbi.nlm.nih.gov/sites/entrez

What have they actually proved?

I got lost in the numbers and acronyms.

Di

Kind of hard to say what they "proved" without the whole article. According to the abstract, they say that adding pulse wave amplitude (whatever that is) to the other measurements during a sleep study will add about 10% to the respiratory disturbance index and that the two people who analyzed the sleep study data were in general agreement.


I think......

I "think" that pulse wave amplitude is the recording pulse oximeter w/the finger sensor probe. I wonder how old that article is? They used a recording pulse oximeter finger clip during my first sleep study back in 1998. Or I am totally wrong (and it wouldn't be the first time).

RiverDave wrote:Kind of hard to say what they "proved" without the whole article. According to the abstract, they say that adding pulse wave amplitude (whatever that is) to the other measurements during a sleep study will add about 10% to the respiratory disturbance index and that the two people who analyzed the sleep study data were in general agreement.


I think......

This is taken from their introduction:

"Photoplethysmography non-invasively measures the relative
absorption of red light and infrared light. Arterial blood flow pulsation passing through an artery modulates the light absorption and provokes a pulse wave easily convertible in an electrical signal readable during PSG. This parameter can be easily derived from conventional pulse oxymeters and does not bring any alteration of sleep,as there is no variation of pressure at the fingertip. It has also been used as a marker of finger vasoconstriction and shown to be more sensitive than HR as an autonomicmarker"

Basically, pulse wave enables us to basically measure the blood "pulsating" through the vascular system. It can be used as an alternative method for identifying an arousal (which may not be seen at the cortical level).

Slinky wrote:I "think" that pulse wave amplitude is the recording pulse oximeter w/the finger sensor probe. I wonder how old that article is? They used a recording pulse oximeter finger clip during my first sleep study back in 1998. Or I am totally wrong (and it wouldn't be the first time).

The paper was recently published.

Here's a picture showing what a pulsewave looks like and what happens during and after a hypopnea. You can see that the pulsewave amplitude decreases during an arousal. This indicates vasconstriction of the vascular system (increased sympathetic drive ala what happens when adrenaline is pumped into the system)

Split_city,

So its sort of a blood pressure reading (systolic reading, anyway) taken with light rather than mechanical force?

RiverDave wrote:Split_city,

So its sort of a blood pressure reading (systolic reading, anyway) taken with light rather than mechanical force?

correct