II. Indications
-
Myasthenia Gravis
- Evaluate for Respiratory Failure (Bellows Failure) in myasthenia crisis
- Used in combination with Forced Vital Capacity (FVC) and negative Inspiratory Force (NIF)
- Respiratory Assessment in other acute respiratory illness
- Has been used as a triage tool in Telemedicine (e.g. Covid19)
III. Technique
- Patient count out loud as high as they can after a single inhalation
IV. Interpretation
- Normal: 40 to 50
- Risk for Respiratory Failure (need for Ventilatory support): 15 to 20