Peak Flow Procedure
Common Sources of Error
- Failure of patient to take full inspiration or expiration.
- Patients ‘preparing’ themselves by taking repeated deep breaths.
- Patients dislike of and difficulty using the mouthpiece due to loose dentures etc.
- Faulty technique
"A number of factors e.g. not fully inflating the lungs, breathing out too slowly can make the reading inaccurately low. An inaccurate high reading can occur if the patients tongue is inside the mouthpiece during exhalation, coughing during the manoeuvre, or the pointer has not been reset to zero. By selecting the highest reading patients minimise these sources of error". (Reinke et al, 2000).
- Poor posture.
- Equipment failure.
References
- British Medical Association and Royal Pharmaceutical Society (2002) British National Formulary No. 43 London: BMA & RPSGB
- British Thoracic Society and Association of Respiratory Technicians and Physiologists (1994) Guidelines for the measurement of respiratory function Respiratory Medicine Vol. 88 pp. 165- 194
- Reinke, L. and Hoffman, L (2000) Asthma Education - Creating a partnership Heart and Lung Journal of Critical Care Vol. 29 No. 3 (May) pp. 225-236
Text Authors: Lesley Coote, Teresa Burgoyne, Julie Morgan
Respiratory Service, QMC NNPDG Link Member: Philip Daly
2002 Review Date : 2005
Suggested Audit Points
- Are peak flows being recorded and documented?
- Is action being taken on unexpected low reading?
- Is the patient’s technique correct?
- Has the procedure been explained to the patient?