Spirometer
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A spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs. It is a precision differential pressure transducer for the measurements of respiration flow rates. The spirometer records the amount of air and the rate of air that is breathed in and out over a specified time. The Spirometer and attached flow head function together as a pneumotachometer, with an output signal proportional to airflow.
See also: respiratory system, lung volumes
Peak flow Peak flow measurement is becoming an important guide to pulmonary or lung function. Peak flow meters record the maximum speed of a diameter of the respiratory tubes. Peak flow can be more accurately measured using the medical spirometer and this should be used in the first measurement to get a base line. You can also use electronic peak flow meters but their accuracy is in doubt. People with moderate to severe asthma use peak flow meters to monitor their condition and therapy. Also chronic bronchitis and emphysema sufferers monitor their lung function the same way, as do people requiring chest physiotherapy and athletes in training. The peak flow of the forced expiration occurs in the first 100milliseconds. Normal range for men is 500-700 litres or dm per min, women are 380-500dm3/min. Children are less depending on height and chest size. A client that has no symptoms of asthma has a ‘standard/bench mark’, obtained by a spirometer and classed as the personal best. The portable device readings can then be calculated on a percentage of the personal best basis and used form monitoring. Clients with readings of 50% or less have severe asthma, 50-80% have moderate asthma, and 80-100% have mild asthma. Peak flow meters should meet specified guidelines for accuracy and precision, but variation between devices made by different manufacturers is unpredictable. Users may contract fungal contamination off of portable peak flow devices so they are encouraged to wash with soap and water, regularly. Other precautions include: · Device should be replaced every 1-2yrs as there is possibility of failure before this time giving misleading data · Forced exhalations into devices can cause some clients to have an attack; these people shouldn’t use peak flow meters. · Inaccurate measurement may promote over medication · Over reliance on peak flow meters may lead to a delay in seeking medical treatment. · Failure to obtain new annual personal best readings may lead to judgement. · There is potential for unrecognised device malfunction · When it’s not possible to subscribe spirometry for initial diagnosis. With a biological spirometer, you breathe in and out f a volume of air trapped by a moveable box inverted over water. As inhalation occurs the box is depressed and re elevated during exhalation, the up and down movement of the box is recorded by an ink pen on a pen on a moving drum covered in graph paper or displayed electronically. The moving gases between the person inhaling and exhaling and the air in the box are in a sealed system and the subject doesn’t move their mouth from the mouthpiece during the activity. Their nose is clipped closed as well. There are several types of spirometer and there must be supervision. Only a few breaths can be taken as the box quickly fills with nitrogen and CO2 and depleted of O2. To reduce this hazard, the spirometer should have a continuous measured supply of O2 piped in and a device for absorbing CO2 gas. There are no dangers of cross infection if mouthpieces are thoroughly cleaned unless they are disposable. Medical spirometers are electronic, portable and client friendly with the results readily available in a printout format