Peak flow meter (Medical students)


The Peak Flow Metre is a handheld device used to measure peak expiratory flow (PEF) – the maximum speed of expiration. Reflects the degree of airway obstruction. The reading reflects the degree of airway obstruction.

Infants and young children (till 6 years) are not able to use the peak flow meter.

Uses
  • Diagnosis – diurnal variability > 20%, improvement of PEFR after bronchodilator or stereoids. Also useful as an assessment of response to treatment.
  • Monitoring – as part of an individual management plan that includes education and symptom recognition (asthma symptoms during the day, interference with sleep, activities e.g. sports). There should be little variation in the reading from day to day, or morning/evening when asthma is well-controlled.
  • Acute exacerbation – less than 50% best/predicted in severe attack; less than 33% in life-threatening attack or unable to perform measurement. 
Method
  1. Attach mouthpiece.
  2. Set the meter to zero.
  3. Stands up or sit upright.
  4. Hold the meter level (horizontally), keep fingers away from the pointer.
  5. Take a deep breath and close lips firmly around the mouthpiece.
  6. Blow as fast and strongly into the device as possible (as if you were blowing out candles on a birthday cake).
  7. Record the reading on the meter.
  8. Repeat three times and note the highest recorded number (not the average).
Interpretation

Compare the highest value to:
– Personal best (if known).
– Predicted normal values

>80% Green(well controlled, routine medications and activity)
50-80 Yellow (reliever and monitor)
<50% Red (reliever and seek medical attention).