Auto titrating CPAP (APAP) is becoming more widely used over conventional fixed pressure CPAP for a number of reasons. The algorithms have developed significantly since the original APAP devices became available and are now able to differentiate between central and obstructive apnoeic events and respond accordingly where they once were not able to do so. APAP may also be more easily tolerated by patients, particularly at very high pressures, as the device always seeks to deliver the lowest therapeutic pressure and as a result may provide lower average pressures overnight. Other patients may simply not have access to a sleep laboratory for a CPAP titration study due to geographical or financial restrictions. For this reason, patients are often initiated on APAP therapy for a trial period in order to determine an appropriate fixed pressure.
In this study by Dias et al, the investigators looked to determine how long it would take for an APAP trial to gather enough data to determine an effective and stable PAP level.
62 patients were evaluated after 3 months of APAP therapy, and data was collected corresponding to the first day (D1), first week (W1), seventh week, (W7), and twelfth week (W12).
They found a high correlation in the pressure achieved for 95% of the night (95th % pressure) between D1 and W12 (r=0.771), W1 and W12(r=0.817), W7 and W12 (r=0.926). As r gets closer to 1 the correlation is better and this was progressively higher with longer APAP use.
There were significant differences in the pressures found between D1 and W12 however there was no difference in pressure between W1 and W12.
At least one week of APAP therapy was sufficient in this study to determine an effective and stable PAP level.
For this reason it is always important to have a trial of CPAP prior to purchasing equipment and a follow up with your Doctor or CPAP provider to ensure your therapy is functioning optimally.
