measuring lung volumes Flashcards
(63 cards)
what is breathing rate
the number of breaths per minute
what is oxygen uptake
the volume of oxygen absorbed by the lungs in one minute
what is tidal volume
the volume of air inhaled or exhaled in one breath, usually measured at rest
what is a spirometer
a device that can measure the movement of air into and out of the lungs
what is vital capacity
the greatest volume of air that can be expelled from the lungs after taking the deepest possible breath
what are the three ways to measure the capacity of the lungs
- peak flow meters
- vitalographs
- spirometer
what is a peak flow meter
measures the rate at which air can be expelled from the lungs. people with asthma often use these to monitor how well their lungs are working
what is a vitalograph
the patient breathes out as quickly as possible through a mouthpiece. the instrument produces a graph of the amount of air they breathe out and how quickly its breathed back in
how do we use a spirometer
a float chamber spirometer consists of a chamber of air or medical grade oxygen floating on a tank of water. during inspiration, air is drawn from the chamber so the lid moves down. during expiration, the air returns to the chamber raising the lid
how is the movement of air recorded
on a datalogger
what happens to the carbon dioxide rich air that is exhaled
it is passed through a chamber of soda lime which absorbs the carbon dioxide
what does the soda lime allow to be measured
oxygen consumption
what can many spirometers not measure
the rate of oxygen consumption
what are the precautions that must be taken when using a spirometer
- the subject should be healthy and in particular free from asthma
- the soda lime should be fresh and functioning
- there should be no air leaks in the apparatus as this would give invalid or inaccurate results
- the mouthpiece should be sterilised
- the water chamber must not be overfilled (or water will enter the air tubes)
what is tidal volume
the volume of air inhaled or exhaled during relaxed breathing
when is tidal volume usually measured
at rest
what is tidal volume sufficient for
supplying all the oxygen in the body at rest
what is the tidal volume in an average adult
0.5dm3 or 500cm3
what is tidal volume 15% of
vital capacity
what is inspiratory capacity
maximum possible volume inhaled after a relaxed exhalation
what is expiratory capacity
maximum possible volume exhaled after a relaxed inhalation
what is inspiratory reserve volume
the maximum volume of air you can breathe in, over and above normal inhalation
- the extra air that is breathed in deeply (forcefully) is your IRV
what is the average inspiratory reserve volume in an adult
2.4dm3 or 2400cm3
what is expiratory reserve volume
maximum volume of air you can force out of your lungs over and above the normal tidal volume of air you breathe out
- when you breathe out deeply (forcefully) the extra air breathed out is the ERV