While Reviewing the Chart of a Patient Receiving Postural Drainage

While reviewing the chart of a patient receiving postural drainage therapy, you notice that the patient tends to undergo mild desaturation during therapy (a drop in SpO₂ from 93% to 89% to 90%) . Which of the following would you recommend to manage this problem?

A) Increase the patient's FiO₂ during therapy.
B) Discontinue the postural drainage therapy entirely.
C) Discontinue the percussion and vibration only.
D) Decrease the frequency of treatments.