Which of the following can reduce the effectiveness of CPAP?

The correct answer indicates that alcohol can reduce the effectiveness of CPAP therapy. Alcohol has a sedative effect on the central nervous system, which can lead to increased relaxation of the upper airway muscles during sleep. This relaxation can exacerbate obstructive sleep apnea, the condition for which CPAP is used as a treatment. Consequently, when a patient consumes alcohol, it can lead to a greater number of apneic episodes and potentially reduce the overall effectiveness of the CPAP therapy.

While nasal sprays and antidepressants may affect sleep quality or comfort, their direct impact on CPAP effectiveness is less significant compared to the effects of alcohol. Nasal sprays may actually help alleviate nasal congestion, potentially improving CPAP compliance. Antidepressants can affect sleep architecture but do not have the same immediate negative impact on airway control as alcohol does. Therefore, the focus on alcohol as the most significant factor in reducing CPAP effectiveness highlights its potential to undermine the therapy's goal of maintaining airway patency during sleep.