How is maximum inspiratory pressures (MIP) measured in pulmonary function testing?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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Answer

Answer

For determining MIP, patients breathe through a flanged mouthpiece with nose clips in place. They are instructed to exhale to RV. At RV, a valve or shutter is closed, and the patient is coached to inhale as forcefully as possible. Maximum pull should be maintained for 1-2 seconds. A standardized leak must be present in the measurement system to eliminate significant overstatement of MIP by allowing the cheek muscles to contribute to the measured pressures. Initial maximum negative pressures that cannot be maintained for one full second are ignored.


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