Core Practical 17

• What does a spirometer measure?

  Breathing and respiration
• What is tidal volume?

  Volume of gas in one normal breath
• What does respiratory minute ventilation measure?

  Volume of gas inhaled per minute
• What is vital capacity?

  Volume of gas in one forced deep breath
• How does the spirometer detect changes in gas volume?

  The lid of the chamber moves up and down
• What is the purpose of soda lime in a spirometer?

  To absorb exhaled carbon dioxide
• Why does the subject wear a nose clip during the spirometry test?

  To ensure all breathing occurs through the mouth
• What is the graph produced by a spirometer called?

  Spirogram or spirometer trace
• What equipment is needed for spirometry?

  • Spirometer
  • Datalogger/computer/kymograph
  • Soda lime
  • Disinfectant
  • Nose clip
• What is the first step in calibrating the kymograph?

  Empty the chamber and force air into it
• How is the horizontal scale set on the kymograph?

  Set to 1 mm per second
• Who can fill the spirometer with medical grade oxygen?

  A trained member of staff
• What should be done before the subject breathes into the spirometer?

  Disinfect the mouthpiece and attach it
• What is the maximum duration for breathing into the spirometer?

  5 minutes
• What are the hazards associated with spirometry?

  • Disinfectant: Flammable; keep away from flames
  • Soda Lime: Corrosive; wear eye protection
  • Spirometer: Breathing/circulatory problems; use under supervision
• What should be done in case of a fire caused by disinfectant?

  Put out fire and seek assistance
• What is the safety precaution for handling soda lime?

  Wear eye protection and avoid skin contact
• What should be done if the spirometer causes breathing problems?

  Stop using it and seek medical attention
• How can the spirometer trace be interpreted?

  • Tidal volume: Distance from peak to trough (normal breathing)
  • Vital capacity: Distance from peak to trough (forced deep breath)
  • Breathing rate: Number of peaks per minute
  • Respiratory minute ventilation: Breathing rate × tidal volume
• What happens to tidal volume after exercise?

  Tidal volume increases
• What happens to vital capacity after exercise?

  Vital capacity remains the same
• What happens to breathing rate after exercise?

  Breathing rate increases
• What happens to respiratory minute ventilation after exercise?

  Respiratory minute ventilation increases
• Why does respiration increase during exercise?

  More oxygen is required due to muscle contraction
• What occurs after reaching the maximum aerobic rate?

  Minute ventilation plateaus and respiration becomes anaerobic
• What should be obtained before using the spirometer?

  Informed consent
• What rights do participants have in the spirometry experiment?

  They can refrain from participating or stop at any time