VOL: 96, ISSUE: 38, PAGE NO: 49
PHIL JEVON, RESUSCITATION TRAINING OFFICER; BEVERLEY EWENS, CLINICAL NURSE SPECIALIST, MANOR HOSPITAL, WALSALL
JOAN MANZIE, RESPIRATORY NURSE SPECIALIST, AT MANOR HOSPITAL, WALSALLPeak expiratory flow (PEF) or peak flow is defined as 'the maximum flow achievable from a forced expiration starting at full inspiration with an open glottis' (BTS & ARTP, 1994). It is a simple, cost-effective test in the assessment of respiratory disease.
Peak expiratory flow (PEF) or peak flow is defined as 'the maximum flow achievable from a forced expiration starting at full inspiration with an open glottis' (BTS & ARTP, 1994). It is a simple, cost-effective test in the assessment of respiratory disease.
PEF is most commonly used to ascertain the severity of a patient's asthma and to monitor on-going level of control. It can also be used to aid diagnosis, for example, serial peak flow recordings and bronchodilator/steroid reversibility tests.
The normal range for peak flow readings is influenced by age, gender, height and ethnic origin. The readings are usually higher in men than women and the best peak flow usually occurs between the ages of 30 and 40 years. It is therefore important to refer to a recognised table of normal values (Gregg and Nunn, 1973). The patient's recent PEF readings should also be referred to.
Usually, predicted values in adult males are between 450 and 700 litres/min. and in adult females between 300 and 500 litres/min. (Hinds and Watson, 1996). The results should be interpreted in the light of recent bronchodilator use. Results are impaired in the presence of airways obstruction, for example, asthma, chronic obstructive pulmonary disease (COPD), and in restrictive lung conditions, for example, fibrosing alveolitis.
In hospital, PEF readings should be undertaken four times a day, both before and after the administration of bronchodilators (Ross-Plummer, 2000). The results are crucial for assessing how well the patient is responding to treatment. After the acute phase, morning and evening PEF readings should be taken and continued by the patient after discharge.