Peak flow meters are an important tool in our kit bag in measuring the volume and effectiveness of somebody’s lung capacity and the way they are breathing. It is most commonly used with patients with aspro bronchitis and emphysema or people who are covered by COPD, chronic obstructive pulmonary disease, a reduction in the way the lung works and the efficiency of the lung. The meter itself has a mouthpiece where the air enters the airway measuring system. There’s a scale on the outside which measures the amount of air that we blow into the unit itself. It also has two different types of mouthpieces. The most common one used is the one-use cardboard tube that is disposable and they also come with a clean sterile reusable mouthpiece. These tend to be the ones that we don’t use very often for contamination purposes. The most common is the cardboard roll.
The cardboard roll itself pushes into the end of the airway, peak flow meter, the patient then must make a seal around the cardboard tube. One or two little problems that we have with this is to get a good flow, the patient’s tongue and teeth need to be clear of the actual inlet valve. They need to take then a deep breathing, as deep as they possibly can, and in one short blow, they fast empty their lungs into the meter and the needle and the register will raise to give you a measure of the capacity and the force the air has left the lungs. This must be repeated three times and we take the highest score of the three tests to give us the level and capacity of the lung of the patient. We need this as a baseline obs or a baseline set of observations to tell us how effective our treatment is.
Once we have administered drugs or nebulisation, their lung capacity should improve. The only way we can find that out is by taking an initial reading than doing the tests giving the drugs. Once the drugs get into the system, we repeat the three blows and measure again after treatment and we should have an improvement in the capacity of the lungs. This gives us some idea that the treatment is working and we can evidence that on our patients report forms. They need to do the three blows before but it is not absolutely crucial. If you encounter a patient that has a very severe breathing problem, do not waste time taking peak flow readings.
If they are not capable of doing the peak flow reading because their breathing is in too much distress, treat the patient first, look after the patients best interest, and write on your patients report form that the patient was too ill or the breathing was too bad to perform a peak flow reading. Once their breathing has improved, you then complete your peak flow reading and you then document that they were unable to complete the peak flow at the start. But after treatment, they did a complete review of their lung capacity and the reading was whatever found on the meter. So we don’t have to use it, but it’s beneficial to use it where we can.
Peak flow calculations are used when assessing a patient with Asthma.