Contributed by James A. Rowley, MD and M. Safwan Badr, MD
What is the respiratory event illustrated in this fragment (5 minutes of recording time)?
Legend: LOC: left oculogram; CHIN1-CHIN2: chin EMG; C3A2: central EEG leads; LLEG: left leg EMG; SNOR: snoring channel; pFLOW: nasal pressure flow channel; PES Waveform: esophageal pressure trace; THORAX: thorax effort channel; ABDM: abdominal effort channel; SAO2: oxygen saturation channel.
The new AASM scoring manual defines a respiratory effort related arousal as follows: ‘If there is a sequence of breaths lasting at least 10 seconds characterized by increasing respiratory effort or flattening of the nasal pressure waveform, leading to an arousal from sleep when the sequence of breaths does not meet criteria for an apnea or hypopnea.’ The key characteristics are illustrated in the fragment: increasing respiratory effort (red arrow), flattening of the nasal pressure waveform (blue arrow), followed by an arousal (box).
The new AASM scoring manual provides two definitions of a hypopnea:
- Drop by ≥30% of baseline in the nasal pressure signal accompanied by a 4% desaturation from baseline (recommended definition); or
- Drop by ≥50% of baseline in the nasal pressure signal accompanied by a 3% desaturation from baseline (alternative definition)
As there is no evidence of desaturation in the fragment, this event does not meet the definition of a hypopnea.
Reference: The AASM Manual for the Scoring of Sleep and Associated Events. Westchester, IL: AASM, 2007, page 46.
Legend: LOC: left oculogram; CHIN1-CHIN2: chin EMG; C3A2: central EEG leads; LLEG: left leg EMG; SNOR: snoring channel; pFLOW: nasal pressure flow channel; PES Waveform: esophageal pressure trace; THORAX: thorax effort channel; ABDM: abdominal effort channel; SAO2: oxygen saturation channel.
