During a PAP titration, signal flattening in the nasal pressure monitor indicates:

During a PAP titration, signal flattening in the nasal pressure monitor indicates:

• A. Snoring
• B. Hypoventilation
• C. Central apnea
• D. Flow limitation

Answer: (D)

In PAP titration, the nasal pressure signal is used to estimate airflow from the upper airway. When the airway is only partially blocked, air can still move but with resistance, creating a plateau or flattened appearance in the inspiratory portion of the nasal pressure waveform. This flattening specifically indicates flow limitation—airflow is being limited by airway resistance even though breathing continues. It’s the pattern clinicians look for to identify incomplete airway opening and to titrate pressure upward until the flow becomes unobstructed and the waveform normalizes. Snoring is an audible sign of vibration from the airway but doesn’t define the flow signal pattern; hypoventilation and central apnea involve different pathophysiology and would show different signals rather than a characteristic flattening.

In PAP titration, the nasal pressure signal is used to estimate airflow from the upper airway. When the airway is only partially blocked, air can still move but with resistance, creating a plateau or flattened appearance in the inspiratory portion of the nasal pressure waveform. This flattening specifically indicates flow limitation—airflow is being limited by airway resistance even though breathing continues. It’s the pattern clinicians look for to identify incomplete airway opening and to titrate pressure upward until the flow becomes unobstructed and the waveform normalizes. Snoring is an audible sign of vibration from the airway but doesn’t define the flow signal pattern; hypoventilation and central apnea involve different pathophysiology and would show different signals rather than a characteristic flattening.