Lung Volumes and Gas Distribution - Testing Equipment

1
Lung Volumes and Gas Distribution - Testing
Equipment

• RET 2414L
• Pulmonary Function Testing
• Module 3.1

2
Lung Volumes / Gas Distribution

• Open-Circuit N2 Washout

3
Lung Volumes / Gas Distribution

• Open-Circuit N2 Washout
• Equipment Required
• Spirometer
• Tissot a water-sealed spirometer with a volume
  of approximately 100 liters. Designed for
  collecting large volumes of exhaled air
• Pneumotachometer

4
Lung Volumes / Gas Distribution

• Open-Circuit N2 Washout
• Equipment Required
• Free- Breathing valve
• Valve is opened or closed either manually or by
  computer control to allow patient to be switched
  from breathing room air to breathing gas from
  spirometer or special circuit
• Deadspace of valve is determined by closing off
  all ports and filling the valve with water. The
  volume of water is the deadspace volume
• Oxygen source

5
Lung Volumes / Gas Distribution

• Open-Circuit N2 Washout
• Equipment Required
• Nitrogen analyzer
• Giesler Tube Ionizer
• Measurement on the basis of photointensity
  (emission spectroscopy)
• Sample is pumped (vacuum pump) into an ionizer
  chamber where a light is emitted and monitored by
  a phototube. Intensity of light is directly
  proportional to the percent of N2

6
Lung Volumes / Gas Distribution

• Open-Circuit N2 Washout
• Equipment Required
• Nitrogen analyzer
• Measurement range (0 80)
• Calibrate to zero using 100 O2 (0 N2) and a
  known concentration of N2
• Troubleshooting
• Sporadic or erratic zero readings which return to
  the expected value are caused by aspiration of
  water through the needle valve

7
Lung Volumes / Gas Distribution

• Single-Breath N2 Washout
• Equipment Required
• Same as equipment used for open-circuit N2
  washout

8
Lung Volumes / Gas Distribution

• Closed-Circuit He Dilution

9
Lung Volumes / Gas Distribution

• Closed-Circuit He Dilution
• Equipment Required
• Spirometer
• Volume displacement
• Directional breathing circuit
• Free breathing valve
• He source
• O2 source
• Allows addition of O2 during test to replenish O2
  consumed by patient
• Maintains constant system volume

10
Lung Volumes / Gas Distribution

• Closed-Circuit He Dilution
• Equipment Required
• He analyzer
• Thermal conductivity analyzer (wheatstone bridge)
• Measurement range (0 10)
• Calibrate to room air (0 He) and a know amount
  of He (10), then re-zero.
• CO2 and water vapor must be removed from gas
  prior to being analyzed

11
Lung Volumes / Gas Distribution

• Closed-Circuit He Dilution
• Equipment Required
• Fan or Blower
• Promotes gas mixing within a rebreathing circuit
• CO2 absorber (Scrubber)
• Needed for tests requiring rebreathing
• Sodium hydroxide (NaOH) Soda lime
• Light brown to white - exhausted
• Barium hydroxide (BaOH2) Baralyme
• White to purple exhausted
• By product is water
• Place upstream from H2O absorber

12
Lung Volumes / Gas Distribution

• Closed-Circuit He Dilution
• Equipment Required
• H2O absorber
• Removes moisture as patient breaths through the
  system
• Moisture adversely affects analyzer
• Calcium sulfate (CaSO4)
• Place in-line after CO2 absorber
• Desiccant color changes from blue to pink when
  exhausted

13
Lung Volumes / Gas Distribution

• Body Plethysmograph
• AKA Body Box

14
Lung Volumes / Gas Distribution

• Body Plethysmograph
• Two types
• Constant-volume, variable-pressure
• Pressure Plethysmograph
• Flow or variable-volume
• Flow Plethysmograph
• Both measure thoracic gas volumes and airway
  resistance and it derivatives
• Both use a pneumotachometer to measure flow and a
  mouth transducer with a shutter to measure
  alveolar pressure

15
Lung Volumes / Gas Distribution

• Body Box
• Calibration
• Mouth pressure is verified with a mercury or
  water barometer
• Flows are verified with a rotometer
  (flow-metering device) or a 3-liter syringe
• Box pressure is calibrated by using a sine-wave
  rotary pump
• simulates inspiratory/expiratory volumes