spirometer

• method

  • A canister containing soda lime is inserted between the mouthpiece and the floating chamber. This absorbs the carbon dioxide that the subject exhales.
  • the spirometer is filled with oxygen. A disinfected mouthpiece is attached to the tube, with the tap positioned so that the mouthpiece is connected to the outside air.
  • the subject puts on a nose clip and breathes through the tube when comfortable
  • Switch on the recording apparatus and The trace will move down as the person breathes in.
  • After breathing normally-take as deep a breath as possible and then exhale
• results

  • tidal volume= the volume of air breathed in and out in one breath at rest. The tidal volume for most adults is only about 0.5 dm³.
  • Vital capacity=maximum volume of air that can be breathed in or out of the lungs in one forced breath.
  • Breathing rate= number of breaths taken per minute.
  • Minute ventilation is the volume of air breathed into (and out of) the lungs in one minute.
• Minute ventilation = tidal volume × rate of breathing (measured as the number of breaths per minute)
• Some air (about 1 dm³) always remains in the lungs as residual air and cannot be breathed out. Residual air prevents the walls of the bronchioles and alveoli from sticking together. Any air breathed in mixes with this residual air.