"My" PRS1 also had a bunch of old stuff on the SD card including AHIs in the thousands. A lot of graphs appeared blank simply everything was being scaled to those large numbers. That is to say - if the highest value of the graph is 5000, then a 5 or 6 won't even be a blip off the baseline, and it looks like nothing's been recorded.
I got instructions from another forum how to get around this. I don't know if it's outside the Apnea Board rules to publish a link to a different forum, but if you send me a PM I'll give you the link.
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