How to Interpret CPAP Data

Most newer CPAP machines record a great deal of data about the sleep patterns of the patients who use them. This data is often saved on a smart card that the patient can take along to the doctor or respiratory therapist's office; some machines report the data directly via wireless modem. While each CPAP model records a slightly different set of information, there are a few basic pieces of data that show up in all reports. This information helps therapists tell whether the patient is complying with treatment and whether the CPAP machine or mask needs to be adjusted.

Things You'll Need

• CPAP data report

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Instructions

• 1

  Look at compliance data to judge whether the patient is actually following his or her treatment regimen. Most reports will show both total hours of use and total days of use for a given period. If total days of use is smaller than the prescribed period length, it indicates the patient is skipping CPAP therapy; if the total number of hours of use divided by days of use is six or fewer, it may indicate the patient is removing his mask at some point during the night.

• 2

  Review apnea/hypopnea data to judge effectiveness of treatment. The apnea/hypopnea index, or AHI, is an hourly average of how many times the patient stops breathing or is not inhaling fully. An AHI of greater than 5 is an indication that the treatment is not being effective; either the CPAP machine is not providing adequate pressure or the mask is not properly fitted. The report may also show the average length of apnea/hypopnea episodes.

• 3

  Look at pressure data to indicate how much pressure the patient requires to prevent apnea episodes. The most recent CPAP designs adapt the amount pressure the patient receives according to the breathing rate data it's measuring. This pressure is usually expressed both as an average pressure (in cm/H2O) and as a percentile pressure. The percentile pressure is the pressure at which you spent that percent of time at or below. For instance, if the report shows a 90 percentile pressure of 11, it means that 90 percent of the time you were using your CPAP, you were receiving 11 cm/H2O of pressure or less. If these pressures are close to the maximum pressure at which the machine is set, it can be an indication that the patient requires a higher maximum pressure.

• 4

  Examine leakage data to determine proper mask fit. A certain amount of air escaping from a CPAP mask is necessary to prevent the patient from rebreathing the same air; however, too much leakage indicates the patient may not be receiving the correct air pressure from the mask. The report typically shows the leakage data in l/min, as both an average and as a percentile. It may also show how much time was spend with excessive leakage from the mask.