A peak flow meter is one way to determine the severity of your asthma. It measures your maximum speed of expiration, or peak expiratory flow rate (PEFR or PEF). Peak flow readings are higher when your asthma is well managed and airways are relaxed and lower when your asthma is worse and the airways are constricted. Your doctor will determine your optimal peak flow measure and advise you to take action if it drops below a certain threshold.
Peak flows are highly individual and the normal expected value depends on a number of factors including sex, age and height. Due to the wide range of ‘normal' values and high degree of variability, peak flow is not the recommended test to identify asthma. However, it can be useful in some circumstances.
In people with a genetic predisposition to asthma, over-breathing is known to cause bronchospasm.1 2 3 4 In fact, in asthmatics even a single deep breath of the kind taken for performing lung function tests, can bring on a coughing fit or an asthma attack. This is because even one deep breath can increase airway resistance by 71% while arterial carbon dioxide tension is reduced by 7 to 16mmHg. 5
It follows that PEF and FEV1 lung function tests may not be appropriate tests for testing asthmatics, because the testing procedure alters the quantity being measured. In other words peak flow measurements can exacerbate your asthma. The more readings you take, the worse your asthma.
This is why Buteyko practitioners do not recommend regular peak flow monitoring of asthma; a better measure of asthma being symptom severity and frequency of reliever medication use. Asthma Foundation guidelines recommend that if reliever medication (Ventolin, Salamol, Bricanyl) use exceeds 3-4 puffs per week you should review your asthma management strategy with your healthcare provider.
At the Buteyko Clinic we can offer you a full breathing assessment and assess your asthma severity. You will also learn a simple technique to measure your asthma without provoking symptoms. But most importantly, we will give you an asthma management strategy and guide you through simple steps to help better control your asthma naturally.
- Cluff RA. Chronic hyperventilation and its treatment by physiotherapy: discussion paper. J R Soc Med. 1984;77(10):855-62.
- Waites TF. Hyperventilation--chronic and acute. Arch Intern Med. 1978;138(11):1700-1.
- Lum LC. Hyperventilation: the tip and the iceberg. J Psychosom Res. 1975;19(5-6):375-83.
- Sher TH. Recurrent chest tightness in a 28-year-old woman. Ann Allergy. 1991;67(3):310-4.
- Gayrard P, Orehek J, Grimaud C, CHarpin J. Bronchoconstrictor effects of a deep inspiration in patients with asthma. Am Rev Respir Dis. 1975;111(4):433-9