Hi, I am new here and am concerned about my son. He is 8 yrs old and may have ADHD, which led us to get a sleep study done. I do have the report in front of me and do not understand a whole lot of it. The doctor was mostly concerned about his CO2 levels and really only talked to me about that. The written findings are as follows:"No epileptiform changes were seen on the EEG. Sleep architecture was characterized by borderline prolonged sleep onset latency after a bedtime of 2052. REM sleep latency was prolonged. REM sleep volume was diminished. Slow-wave sleep was seen on this study. Slow-wave sleep was seen in abundance. Overall sleep efficiency was normal at 90%. Breathing was characterized by an absence of snoring. Apneas, hypoapnea, and respiratory event-related arousals were noted on this study at an overall rate of 1.5 per hour of sleep. Low oxygen saturation was 92%. End-tidal carbon dioxide was abnormal with about 70% of the night's having end-tidal carbon dioxide levels above 45 mmHg during sleep. EKG was unremarkable. Leg kicking movements were rare on this study, about 1 per hour, and arousal is rare." My questions are what is the significance of the comments on REM and slow-wave sleep? Is the low oxygen saturation of 92% normal or acceptable? What does end-tidal mean? Any help or insight anyone can provide would be much appreciated.

I know those reports can look something like a foreign language sometimes.  Let me attempt to translate into some dialect of english:  

"We didnt see any indication of seizures.  It took a while for the patient to fall asleep after he went to bed at 8:52.  After he fell asleep  it took him longer to go into stage REM, than the norm for his age.  He also had less REM than the normal child his age.  We saw some deep sleep on this study.  We saw an abundance of deep sleep on this study.  After the patient went to bed, he was asleep 90% of the time in bed until morning lights on.  He didnt snore while breathing.  Apneas and hypopneas were only seen 1.5 times per hour, which is considered to be relatively mild.  His oxygen saturation did not go lower than 92%, which is relatively good, considering that this was likely only for a short period of time, and is still considered to be in the "safe range.  Ideal oxygen saturations are above 95%, however it is common for them to dip below occasionnaly for short periods of time.  The amount of residual carbon dioxide that was left over after each breath was a little high.  We usually like to see this range between 25-45mmHg during the night.  His heart rhythm and rate were fine.  He didnt kick his legs much, which would have been a sign of restless leg syndrome or periodic limb movement disorder.  This only happened once each hour, and when it did happen, it did not wake him up, so it is not considered significant."

I know that was a little sarcastic, but here is maybe a little help with your questions:
The REM amounts are not necessarily significant.  Sometimes people may get less REM just because they are in the sleep lab and they had lower quality sleep.  OR...(and here is the answer that I would put more stock in):  If your child was awakened earlier in the morning than he is used to, or got less sleep overall than he is used to, then his sleep/circadian was shifted that night.  Most people have their biggest REM period early in the morning, so if the lab woke your son before his final REM period, then it would look like he had less than he should have on the report.  Often adult labs wake up all patients at the same time.  This is fine for adults because they require less sleep, but kids may need more sleep, and their cycle of sleep is different, so their REM numbers may look attenuated on sleep studies in adult labs.  

Dont worry about the slow wave sleep part.  Slow wave sleep is GOOD.  Slow wave sleep is important for growth, function and development; especially in young kiddos.  

End tidal means the amount of carbon dioxide left at the end of the breath...or carbon dioxide that wasnt exhaled on the last breath.  Carbon dioxide levels are important to measure in kids.  Excessive carbon dioxide levels can effect the drive to breathe, which could be causing the mild apnea/hypopnea events.  

Tim