Ventilation / Ventilation Control Tests - Equipment and Equations

1
Ventilation / Ventilation Control Tests -
Equipment and Equations

• RET 2414L
• Pulmonary Function Testing
• Module 5.0

2
Equipment and Equations

• Ventilatory Response to O2

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Equipment and Equations

• Ventilatory Response to O2
• Equipment Required
• Spirometer
• Pneumotachometer to measure ventilation
• Pressure Transducer / Mouth Shutter
• Allows measurement of P100
• Bag-in-Box Circuit
• Allows the patient to rebreathe into a bag to
  which CO2 or O2 can be added
• Adjustable Blower
• Allows the level of CO2 in the system to be
  maintained at baseline levels (isocapnia)

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Equipment and Equations

• Ventilatory Response to O2
• Equipment Required
• CO2 Scrubber
• Gas Source
• O2 / CO2
• Gas analyzers
• O2 / CO2
• Pulse Oximeter
• Provides data on the patients saturation

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Equipment and Equations

• Ventilatory Response to CO2

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Equipment and Equations

• Ventilatory Response to CO2
• Equipment Required
• Same as that used to measure ventilatory response
  to O2 with two differences
• Bag is filled with 5 to 7 CO2 in O2
• Scrubber is removed from the circuit

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Case 4 - 1

• T.J. is a 45-year-old man admitted to the
  hospital for acute shortness of breath. He has
  never smoked but has a family history of heart
  disease. His lungs are clear during
  auscultation. He becomes breathless just moving
  around the hospital room. He denies any recent
  respiratory infections. Because of his rapid
  respiratory rate, his attending physician
  requested an arterial blood gas test using room
  air and VD/VT ratio determination
• Age 45 Weight 175
• Height 67 Race White

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Case 4 - 1

• Blood Gas Analysis
• pH 7.49
• PCO2 29
• PO2 102
• HCO3- 21
• Hb 14.2
• SaO2 98
• Exhaled Gas Analysis
• 24.2 L/min
• fB 20 breaths/min
• PECO2 14 mm Hg

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Case 4 - 1

• Determine VT
• VT ____
• fB
• 24.2
• 20
• VT 1.21 L

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Case 4 - 1

• Determine VD/VT
• VD/VT PaCO2 PECO2
• PaCO2
• (29 14)
• 29
• VD/VT 0.517 or 52

• Remember, normal is 20 - 40

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Case 4 - 1

• Determine
• fB (VT VD)
• Where VD (VD/VT)(VT)
• VD 0.517 (1.21)
• VD 0.626
• Substituting this value for the alveolar
  ventilation equation
• 20(1.21 0.626)
• 20(0.584)
• 11.68

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Case 4 - 2

• T.B is a 37-year-old man who weighs 275 lb. He
  was referred to the PFT Laboratory after
  evaluation in the sleep laboratory revealed
  obstructive sleep apnea (OSA). He admits to
  daytime somnolence. Baseline PFTs revealed the
  following
• ACT Predicted
• FVC 3.2 72
• FEV1 2.7 81
• FEV1 84 75 85
• TLC 4.1 71
• RV/TLC 22 20 35

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Case 4 - 2

• Baseline blood gas results were as follows
• pH 7.36
• PCO2 47
• PO2 77
• HCO3- 28
• SaO2 93

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Case 4 - 2

• CO2 response test was performed (breathing a
  mixture of 7 CO2 in O2 for 4 minutes). The
  following lab data was obtained
• PetCO2 mm Hg (L/min) P100 (cm H2O)
• 43 4.5 2.2
• 46 4.4 ----
• 50 5.9 ----
• 54 7.9 7.8
• 57 15.1 ----
• 59 17.1 12.0
• What is the interpretation of
• Ventilatory response to CO2 stimulation?
• Respiratory drive response to CO2 stimulation?

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Practice Quiz Module 5.0

• A patient with asthma has the following data
  recorded
• 5.7 L/min
• fB 15
• What is the patients VT?
• 0.15 L
• 0.32L
• 0.38L
• 0.44L

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Practice Quiz Module 5.0

• In which of the following condition would
  increased minute ventilation be expected?
• Metabolic acidosis
• Hypoxemia
• Central nervous system depression
• CO2 narcosis
• I and II only
• III and IV only
• I, II and III
• II, III and IV

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Practice Quiz Module 5.0

• In addition to PaCO2, what other measurement is
  needed to calculate the VD/VT ratio?
• Tidal volume
• Minute ventilation
• Mixed expired CO2
• PaO2

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Practice Quiz Module 5.0

• Which of the following VD/VT rations would be
  expected in a patient with a diagnosis of
  pulmonary embolism?
• 0.09
• 0.15
• 0.25
• 0.50

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Practice Quiz Module 5.0

• A COPD patient has his dead space measured as
  0.4L. If he is breathing at a rate of 16/min
  with a VT of 0.8 L, what is his VA?
• 1.21 L
• 6.4 L
• 12.4 L
• 12.8 L

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Practice Quiz Module 5.0

• Exhaled gas is collected for 10 minutes the
  mixed expired PCO2 is measured. Blood gases are
  drawn during the last minute of gas collected,
  and the following data are recorded
• PECO2 28 mm Hg
• pH 7.38
• PaCO2 44
• PaO2 69
• What is the patients VD/VT ratio?
• 0.63
• 0.57
• 0.41
• 0.36

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Practice Quiz Module 5.0

• A patient has the following results after 4
  minutes of a CO2 rebreathing test
• Time 0 4 minutes
• PetCO2 40 60
• VE 4.0 64.0
• These findings are consistent with which of the
  following?
• Interstitial pulmonary fibrosis
• Obesity-hypoventilation syndrome
• COPD
• Normal lung function

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Practice Quiz Module 5.0

• Which of the following measurements are
  consistent with the diagnosis of
  hyperventilation?
• PaCO2 of 29 mm Hg
• of 6.5 L/min
• pH of 7.52
• VD/VT of 0.49
• I and III only
• II and IV only
• I, II and IV
• I, II, III and IV

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Practice Quiz Module 5.0

• P100 is which of the following?
• Pressure during the first 100 msec of an occluded
  breath
• PaO2 when the patient breaths 100 L/min
• Minute ventilation when the patient is breathing
  100 O2
• Mouth pressure at a respiratory rate of 100/min