NED Mean (Negative Effort Dependence)
A per-breath measure of flow limitation calculated as the ratio of peak inspiratory flow to mid-inspiratory flow. Higher values indicate more airway narrowing during inhalation.
What Is NED Mean (Negative Effort Dependence)?
Negative Effort Dependence (NED) is a per-breath metric that quantifies flow limitation by comparing peak inspiratory flow (Qpeak) to flow at the midpoint of inspiration (Qmid). The formula is NED = (Qpeak - Qmid) / Qpeak x 100. When the airway narrows during inhalation, mid-inspiratory flow drops below peak flow, producing a higher NED value.
The NED Mean is the average of this ratio across all breaths in the night. It provides a sensitive, specific measure of the classic flow limitation pattern where the airway progressively narrows during each breath. A NED Mean below 15% indicates well-controlled breathing effort, while values above 25% suggest significant airway narrowing.
The NED engine also computes several related metrics: Flatness Index (mean/peak flow ratio per breath), Tpeak/Ti ratio (time to peak flow as a fraction of inspiratory time), M-shape detection (identifying breaths with characteristic mid-inspiratory dips), and automated RERA detection (sequences of flow-limited breaths terminated by recovery breaths). Together, these provide a comprehensive per-breath analysis of airway resistance.
Normal Ranges
How AirwayLab Measures This
The NED engine analyses every breath in the flow waveform, computing Qpeak and Qmid for each inspiration. The NED Mean, plus per-breath Flatness Index, M-shape percentage, RERA count, and H1/H2 splits are displayed on the NED Analysis tab in the dashboard.
Try it with your dataFrequently Asked Questions
What does a NED Mean of 20% indicate?
A NED Mean of 20% means that on average across all breaths, mid-inspiratory flow was 20% lower than peak flow. This indicates moderate airway narrowing during inhalation. It falls in the borderline range and suggests some residual flow limitation that may benefit from therapy adjustments.
How is NED different from the Flatness Index?
NED measures the specific ratio of peak flow to mid-inspiratory flow, capturing the classic flow limitation drop. Flatness Index measures the overall ratio of mean flow to peak flow, detecting how rectangular (flat-topped) the breath is. A breath can have high Flatness Index (very flat) but low NED if the flatness is uniform, and vice versa. Both are computed by the same NED engine.
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Medical Disclaimer
AirwayLab is not a medical device and is not FDA-cleared or CE-marked. It is provided for educational and informational purposes only. The analysis results should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult qualified healthcare providers regarding your sleep therapy and any changes to PAP settings.