FIG. 41:  Aside from high loop gain, other PAP-specific mechanisms have been proposed as contributing to TE-CSA.  At higher pressures, when mask leak is more likely to occur, there could be a CO₂ washout and therefore loss of dead space from the mask, which could result in relative hypocapnia to the point of apneic threshold.^[37]  When PAP augments inspiration, again there might be more effective breath-by-breath ventilation that might result in hypocapnia, again to the apneic threshold.  Finally PAP may result in increased stretch receptors in the lung, as well as in the upper airway, leading to central respiratory depression.