1. Ventilation / Ventilation Control Tests - Equipment and Equations
RET 2414L
Pulmonary Function Testing
Module 5.0

2. Equipment and Equations
Ventilatory Response to O2

3. 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)

4. Equipment and Equations
Ventilatory Response to O2
Equipment Required
CO2 Scrubber
Gas Source
O2 / CO2
Gas analyzers
Pulse Oximeter
Provides data on the patient’s saturation

5. Equipment and Equations
Ventilatory Response to CO2

6. 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

7. 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

8. Case 4 - 1 Blood Gas Analysis Exhaled 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

9. Case 4 - 1
Determine VT
VT = ____ fB
24.2 20
VT = 1.21 L

10. Case 4 - 1 Determine VD/VT = (29 – 14) 29 VD/VT = 0.517 or 52%
VD/VT = PaCO2 – PECO2
PaCO2
= (29 – 14) 29
VD/VT = or 52%
Remember, normal is 20% - 40%

11. Case 4 - 1 Determine = fB (VT – VD) Where: VD = (VD/VT)(VT)
Substituting this value for the alveolar ventilation equation
= 20(1.21 – 0.626)
= 20(0.584)
= 11.68

12. 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 %
FEV %
FEV1% – 85%
TLC %
RV/TLC 22% 20 – 35%

13. Baseline blood gas results were as follows:
Case 4 - 2
Baseline blood gas results were as follows: pH
PCO2 47
PO2 77
HCO3- 28
SaO2 93

14. 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)
What is the interpretation of:
Ventilatory response to CO2 stimulation?
Respiratory drive response to CO2 stimulation?

15. Practice Quiz Module 5.0
A patient with asthma has the following data recorded:
: 5.7 L/min
fB: 15
What is the patient’s VT?
0.15 L
0.32L
0.38L
0.44L

16. 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

17. 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

18. 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

19. 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

20. 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:
PaCO2: 44
PaO2: 69
What is the patient’s VD/VT ratio?
0.63
0.57
0.41
0.36

21. Practice Quiz Module 5.0
A patient has the following results after 4 minutes of a CO2 rebreathing test:
Time 0 4 minutes
PetCO VE
These findings are consistent with which of the following?
Interstitial pulmonary fibrosis
Obesity-hypoventilation syndrome
COPD
Normal lung function

22. 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

23. 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