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The Problem – Pulmonary Pressure Measurements How much air are you breathing? If you are ill, is it enough? If you are recovering from a pulmonary disease, when is your breathing adequate? These are questions faced by doctors and their patients every day. The measurement of air in and out of the lungs non-invasively during breathing is an important medical diagnostic tool.
The Solution The measurement of airflow during breathing involves a device called a pneumotach and a differential pressure transducer. A pneumotach consists of a plastic, heated tube with a fine wire mesh mounted inside. As air moves through the mesh, a small differential pressure is generated that is proportional to flow. The heater keeps condensation from occurring as the moist air passes through the cooler mesh; any fluid blocking the air flow will result in an increase in pressure drop. A pneumotach is designed to have a minimal pressure drop, something like 1 or 2 CM H2O at full scale flow rate. This is important because a large pressure drop would require the patient to work harder just to move air through the pneumotach. This extra effort could mask symptoms of disease or similarly mask the progress of healing. A pneumotach will have a pressure drop directly proportional to airflow and its accuracy is about 3%. Pneumotachs are available in several sizes, depending on the maximum flow rate to be measured. There are pneumotachs for premature infants, having very low full scale flow rates, and there are pneumotachs that are sized for adult atheletes having very high full scale flow rates. Transducers for use with pneumotachs must be sensitive to low pneumotach pressures , be cleanable and easily repaired and have a fast response to changing pressures
Validyne Products The Validyne MP45 is specifically designed for use with pulmonary pneumotachs and are available in ranges as low as 2.25 CM H2O. The MP45 can be used with a variety of chart-recorders and other devices capable of receiving a variable reluctance transducer. The MP45 can be disassembled for cleaning and diaphragm replacement in the event of over-ranging.
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| Phone: 818.886.2057 || Email: Sales@validyne.com |
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