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:'''Obstructive Apnea 0.39'''
means that my the patient's OAI = 0.39 on this night. In other words
'''OAI = (number of OAs scored)/(run time) = 0.39'''
'''EPAP 4.00 4.00 4.00 5.00'''
This means that my the patient's minimum EPAP =4, my their median EPAP = 4, my their 90% EPAP = 4, and my their max EPAP = 5. What this tells us is that the their EPAP stayed at 4cm for at least 90% of the night. But the EPAP did get as high as 5cm at some point during the night.
The IPAP line of the table
'''IPAP 6.00 6.00 8.00 8.00'''
means that my the patient's minimum IPAP = 6, my their median IPAP = 6, my their 90% EPAP = 8, and my their max IPAP = 8. That means that the their IPAP stayed at 6cm for at least 50% of the night and the IPAP was LESS THAN or EQUAL to 8 cm for 90% of the night. From this data, we can't tell if the IPAP = 8 for almost 50% of the night or if the IPAP = 8 for only about 10-15% of the night.
'''Statistical Leak Data'''
Total Leaks 11.00 14.00 23.00 34.00'''
The '''Leak Rate''' numbers are SH's statistical "guess" about what my the patient's '''unintentional''' leak rate is. This number is NOT an official Encore number and it does not come directly from the data on the SD card; it is calculated from the Total Leak rate data that is recorded on the SD card.
The '''Total Leaks''' line is the statistical summary of the (raw) leak data. In some sense this may be more trustworthy for people using machines that record total leaks.
'''NOTE:''' ''ResMed S9, PR System One, and F&P Icon machines record Flow Rate data if the card is in the PAP machine during the night; the DeVilbiss IntelliPAP does NOT record Flow Rate data.''
The Flow Rate graph is also referred to as the "wave flow" graph. It provides a record of each and every breath you took all night long. At this scale, everything is all run together; the real power in the Flow Rate graph is when you zoom in sufficiently close to start seeing individual breaths and events. Note that each of the events in the event table shows up as a tick mark on the Flow Rate graph (with the exception of the PR System One VS2 tick marks.) The little boxes appearing on my the sample patient's Flow Rate graph are mostly Pressure Pulses that the PR central detection algorithm uses for testing the patency of the airway.
'''The Pressure graph'''
'''A detailed look at the CPAP Statistics'''
Here is my our sample patient's CPAP Statistics chart:
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[[File:CPAP-statistics_zps1e21a1e7.png]]
The numbers for '''Average hours per night''' is a simple average: Add up the usage for each night in the time period and divide by the number of days in the time period. We can see that the patient didn't get much sleep last night (July 4) and that she is averaging about 6 hours of mask time (and bed time) over the last year. There's a bit of variation between the 7-day, 30-day, 6-month, and 1-year figures, but the variation is not significant.
SleepyHead defines '''Compliance''' for a given night as "usage is at least four hours". The line for defining Compliance can be set in the SleepyHead preferences if desired. The percentage in the '''Compliance''' column is simply the percentage of days in the time period where the usage was at least four hours. The fact that my the patient's 1-year compliance is listed as 96% means that the patient used her CPAP for at least 4 hours on roughly 350 or 351 days. (Both 350/365 and 351/365 round to 0.96). Of the 15 days where she was not compliant, most of them are nights where she got less than 4 hours of sleep. Notably, however, two nights were sleep tests performed during the past summer.
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'''
The 90% leak rates for 30-day, 6-month, and 1-year are found the same way: We line up all the data points for leak rate for the entire time period in increasing order. If there are n points on the entire list, we first find the integer '''k''' that is equal to or just barely bigger than 0.9*n and then we find the '''k'''th number on the list.
The meaning of the long term 90% leak rate is the same as the meaning of the daily 90% leak rate in the Detailed Daily data. The fact that my the patient's 90% 6-month leak rate equals 3.0 means that for 90% of the time the patient's BiPAP has been on in the last 6 months, the unintentional leak rate has been AT or LESS than 3.0 L/min. We can also say that the patient's unintentional leak rate was ABOVE 3.0 for no more than 10% of the time her machine was running in the last 6 months. Which means that long term, she has no serious leak problems to worry about.
'''A detailed look at the Show Leak Redline option'''
The default is to have this checked and the default value for the Redline is the ResMed value of 24 L/min. This is a NEW feature in SleepyHead 0.9.6. Since our sample patient uses a PR System One and she pretty much understands her leaks, she has unchecked the Redline so she doesn't get one in my her daily leak graphs. If you want a line for helping you spot Large Leaks and you are NOT using a ResMed S9 machine, the first thing you will need to do is figure out whether your machine's manufacturer has an official definition of "Large Leak" or not. Here is some information on that:
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SleepyHead should save your graph settings after you've changed them, so you really only need to edit the y-values for the graphs once.
The values that make sense for '''''MYour sample patient's''''' data are probably NOT a good starting point for most people since our sample patient she is a petite 5'1" female who weighs about 110 lbs. That said, here's what the value she typically uses for her graphs look like:
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[[File:preferences5_zpsafcf5d39.jpg]]
Official Large Leaks for PR System One machines are very difficult to determine with great accuracy in versions of SleepyHead prior to 0.9.6. In version 0.9.6, the Encore-defined Large Leaks are flagged by gray bars in the Events table and as a gray background in the Flow Rate curve. The Official Large Leaks for a System One will NOT be flagged directly on the SleepyHead Leak/Total Leak graph.
If you want to add a Redline to your Leak/Total Leak graphs in SleepyHead, my our advice is to look at your own Large Leak flags and figure out where they seem to start. If you don't seem to have very many Official Large Leak, then use the above guidelines as a decent enough starting guess for where your particular Redline should be drawn.<br />
In order to adversely affect the efficacy of your PAP therapy and the accuracy of the data recorded by your machine, leaks have to be both large enough and long enough. As we've just seen, "Large enough" is easily quantified by the manufacturers. But what is "long enough"?
SleepyHead reports that the maximum leak rate topped out at 57.96 L/min, which is 2.5 to 3 times her usual, expected leak rate of 20-25 L/min; the official Large Leak starts when Total Leak graph crosses the 55 L/min line.
Notice how the wave form is severely compressed near the 0 line just before and just after the gap in the wave flow. This indicates that my the patient's BiPAP could not reliably determine whether there was much air going into or out of the patient's lungs. And when the wave form picks up after the gap, it's still pathetic looking. It has none of the characteristics of what her wave form is usually like when she's awake enough to turn her BiPAP off and back on. So she's fully asleep during this leak.
And notice all those Pressure Pulses (the little boxes) right before the gap in the wave form and right after the wave form pics back up? It's likely those PPs are being used by the BiPAP to try to figure out if there's a live, breathing person at the other end of the hose. Perhaps the BiPAP "realizes" that these periods of very low variation in the wave flow are way too long to be a typical apnea or hypopnea, and that's why they are not flagged as such. But it also gets so befuddled about what it's seeing in the wave form data, that the BiPAP concludes she must not be breathing through the mask and so it quits recording Flow Rate data form during the time it cannot determine any meaningful breathing pattern. When this patient showed her DME this wave form pattern (in a different context), the Respiratory Therapist referred to it as a "patient disconnect". (And yes, that tern is bothersome because "patient disconnect" seems to imply that ''the patient'' disconnected the machine from her nose, when she did not do that here or anywhere else). But for now on, we'll call those wave patterns "patient disconnects" even though we don't like that language at all.
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This particular hypopnea's flag is more or less in the middle of the hypopnea. Most of the time the flag is closer to the end of the event, but there is some variability. Another thing that's worth pointing out is that my the patient's BiPAP is in the middle of decreasing the IPAP as part of the PR "search" algorithm; the isolated H does not cause the machine to increase the IPAP and that's a bit counter intuitive to some PAPers. But it is how the PR Auto algorithm works: It ignores isolated Hs and OAs; pressure is increased for events only if two or more events occur very close to each other.
'''Clusters of events'''
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