Can someone explain how EPR reduces flow limitation?

[G. Szabo]

When we increase CPAP pressure, this phenomenon becomes increasingly pronounced. Hence, less and less of the lung's volume can participate in the breathing cycle because of the dead air stuck inside. Therefore, inspiration becomes less and less efficient from the perspective of the oxygen/carbon dioxide exchange process, leading to a special kind of inspiration limitation. Hence, paradoxically, a less efficient exhalation leads to limited inhalation or a particular inhalation flow limitation, which we cannot necessarily see on the flow chart. 

Here are some additional observations that support the importance of EPR.
 
I have palatal prolapse periods, a particular type of expiratory flow limitation. During these periods, my inhalation peaks also become suppressed, i.e., the peaks become smaller and narrower, indicating that the lung cannot take more air because the inhaled air was not fully exhaled. As a result, my oxygen saturation drops from 96% to 93% or even lower.

Conclusion: When EPR increases the efficiency of exhalation (for those without palatal prolapse), it also ensures the optimum volume of inhaled air and maintains high oxygen saturation. 
     

[SeePak]

Szabo.
Good point about the palatal prolapse I too have that and it was pointed out by Patrick McKeown that we should never fully mouth tape must always be able to have our mouth open for air puffing when the prolapse occurs.

Also I have noticed that when the pressure is higher my exhalation time goes up so it seems that my body naturally exhales longer to prevent the problem you suggest can happen for others.