NBRC SAE - Notable Questions

Question 1

3. After several plethysmographic measurements of VTG, a pulmonary function technologist is unable to obtain consistent values. The technologist should instruct the patient to

A. pant deeper and faster.
B. pant gently when the shutter is closed.
C. breathe slowly and deeply.
D. exhale completely before the shutter is closed.

Answer 1

B.√ pant gently when the shutter is closed.

(u) A. Panting deeper may shift lung volumes and generate pressures outside the calibrated range.
(c) B. Panting gently at a rate of 30-60/min when the shutter is closed is the correct maneuver for determining VTG.
(u) C. A panting frequency of approximately 1 per second is adequate to overcome small leaks in the box, such as those used for temperature compensations. See explanation B.
(u) D. Completely exhaling before shutter closure would provide for a measurement of RV.

Question 2

7. An 8-year-old patient with sickle cell anemia is referred for a treadmill exercise (stress) test with pulse oximetry. The following measurements are observed during the procedure:

_________Rest____4 min_____6 min_____8 min_____10 min
BP______98/74____130/70____150/78____152/78____154/78
SpO2_____98______97_______92_______94_______97
HR (min)___88______157______180_______170______190
RR (min)___20______35_______40________45______56

Which of the following should a pulmonary function technologist conclude?

A. The red blood cells are sickling and preventing the uptake of oxygen.
B. Bronchospasm is occurring with exercise, causing desaturation.
C. Motion artifact is preventing an accurate reading of the pulse rate.
D. Increased vasodilatation is caused by increased activity.

Answer 2

C.√ Motion artifact is preventing an accurate reading of the pulse rate.

(u) A. There is no evidence of a change in oxygenation during the test.
(u) B. Bronchospasm would not cause oxygen saturation to drop and then reverse.
(c) C. Motion artifact is causing inaccurate readings in the heart rate and SpO2.
(u) D. There is no indication of vasodilatation.

Question 3

10. A patient’s V̇O2max was determined during a progressive exercise (stress) test on a bicycle ergometer. The test was repeated the next day on a treadmill and the V̇O2 max was 20% less. Which of the following should a pulmonary function technologist conclude?

A. This finding is consistent with published differences between V̇O2max as determined by the ergometer and treadmill.
B. The treadmill test should be repeated and the patient instructed to refrain from supporting his weight on the side rails.
C. The patient pedaled at 30 rpm and needs further instruction.
D. The bicycle ergometer is out of calibration and needs to be returned to the factory.

Answer 3

B.√ The treadmill test should be repeated and the patient instructed to refrain from supporting his weight on the side rails.

(u) A. Published differences show that V̇O2max values on the treadmill are higher than those on a bicycle ergometer.
(c) B. The treadmill test must be incorrect. Treadmill V̇O2max values are usually greater than V̇O2max values achieved on a bicycle ergometer. The observed discrepancy occurs when the patient supports part of his/her weight on the treadmill side rails.
(u) C. A pedal speed of 30 rpm may be too slow on a mechanically braked ergometer. However, this pedal speed may be compensated by an electronically braked ergometer. The observed discrepancy would not be expected on either type of ergometer.
(u) D. V̇O2max is defined as a point where work continues to increase, but V̇O2 does not. Ergometer calibration is not relevant to this measurement.

Question 4

11. A 24-year-old trauma victim received mechanical ventilation for 6 weeks before extubation and early rehabilitation. The following flow-volume loop is obtained and is repeatable:

See “NBRC SAE Exam - Question 11” Image

Which of the following is most likely associated with the shape of the loop?

A. asthma
B. aspiration pneumonitis
C. pulmonary fibrosis
D. upper airway obstruction

Answer 4

D. Upper airway obstruction, as a side effect of long-term endotracheal tube use, would limit inspiratory airflow more severely than expiratory flow because it is outside the chest cavity (extrathoracic).

(u) A. Asthma would affect expiratory flows more than inspiratory flows. See explanation D.
(u) B. Aspiration pneumonitis might cause a decrease in vital capacity, but not inspiratory flow limitation.
(u) C. Pulmonary fibrosis might cause a decrease in lung volume, but no significant inspiratory flow limitation.
(c) D. Upper airway obstruction, as a side effect of long-term endotracheal tube use, would limit inspiratory airflow more severely than expiratory flow because it is outside the chest cavity (extrathoracic).

Note: the image shows a variable extrathoracic obstruction based on the reduced inspiratory flows. An upper airway obstruction is the same as an extrathoracic obstruction.

Question 5

19. An observed PETCO2 in a healthy adult at rest has what relationship with the measured PaCO2 value?

A. The PETCO2 is lower than the PaCO2.
B. The PETCO2 is higher than the PaCO2.
C. The PETCO2 approximates the PaCO2.
D. The PETCO2 is double the PaCO2.

Answer 5

C.√ The PETCO2 approximates the PaCO2.

The PETCO2 generally approximates the PaCO2; therefore, it is unlikely to be significantly higher or lower than, or double, the PaCO2 in a healthy adult at rest.

Question 6

30. A 30-year-old patient is being tested on a computerized cycle ergometer. The computer display indicates 100 watts, but the patient’s VO2 is at 500 mL/min. What is the most likely cause?

A. There is excessive resistance in the cycle ergometer.
B. There is loss of communication with the cycle ergometer.
C. The patient is pedaling at 30 revolutions per minute.
D. The weighted strap has become disconnected.

Answer 6

B.√ There is loss of communication with the cycle ergometer.

(u) A. A higher than normal resistance would be accompanied by the patient’s VO2 being higher than 500 mL/min.
(c) B. The patient’s VO2 is not consistent with 100 watts and is more consistent with unloaded pedaling. This suggests loss of communication between the cycle ergometer and the computer.
(u) C. Pedaling frequency would not explain the discrepancy between the VO2 and the displayed workload of 100 watts on a computerized cycle ergometer.
(u) D. The computerized cycle ergometer does not use a weighted strap for resistance.

Question 7

31. The following pulmonary function data are obtained from a 60-year-old male who is an ex-smoker and is undergoing a disability evaluation:

FVC 2.2 L
FEV1 1.9 L
FEF25-75% 4.1 L/sec
MVV 75 L/min
TLC 2.7 L

Which of the following conclusions should be made concerning the reliability of these data?

A. The FVC is inconsistent with TLC.
B. The FEF25-75% was calculated incorrectly.
C. The patient is malingering.
D. These data can be reported.

Answer 7

D. These data can be reported.

(u) A. The FVC of 2.2 L is consistent with a restrictive disorder, which is also indicated by the TLC and FEV1.
(u) B. The FEF25-75% may be within the normal range in patients with restrictive disorders.
(u) C. The FEV1 and MVV are consistent because one can approximate the MVV by multiplying FEV1 by 35 (= 66.5 L/min). Therefore, malingering is unlikely.
(c) D. The FVC, FEV1, and TLC are consistent with a restrictive process and should be reported.

Question 8

34. Which of the following methods should be used to establish predicted values for a new laboratory?

A. Choose equations from a group similar to the testing population.
B. Use the default settings established by the manufacturer.
C. Average the predicted values from several studies.
D. Select 10 healthy subjects to confirm predicted values.

Answer 8

A. Choose equations from a group similar to the testing population.

(c) A. ATS/ERS recommends selecting predictive equations derived from subjects similar to the population tested.
(u) B. This is commonly done, but it may not be appropriate. See explanation A.
(u) C. Predicted values from several studies should not be averaged under normal circumstances.
(u) D. Global Lungs Initiative recommends 150-300 subjects in each grouping to confirm appropriateness of equations.

Question 9

36. An infrared CO analyzer produces inconsistent readings in response to a calibration gas. Which of the following should a pulmonary function technologist do?

A. Replace the ionization chamber.
B. Refresh the Wheatstone bridge.
C. Adjust the sampling flow.
D. Replace the Nafion (Perma-Pure®) tubing.

Answer 9

D.√ Replace the Nafion (Perma-Pure®) tubing.

(u) A. There is no ionization chamber in this instrument.
(u) B. There is no Wheatstone bridge in this instrument.
(u) C. Adjusting the flow will not cause inconsistent readings since the introduced sample will have a constant concentration.
(c) D. Condensation in the sample chamber will gradually change as the humidity of the introduced sample changes. Nafion (Perma-Pure®) tubing stabilizes the water vapor content of the sample gas to prevent this. This could interfere with the infrared beam and cause the reading to be variable.

Question 10

37. A patient had the following pulmonary function test results at baseline and 6 months after starting bleomycin for lymphoma:

Parameter_______ Baseline_______6-Month Follow-up
FEV1 (L)___________3.90_____________3.80
FVC (L)___________4.59_____________4.50
FEV1/FVC (%)_______85_______________84
TLC (L)____________6.10_____________6.02
DLCO____________30.30____________20.20
V̇ A (L/min)________5.90______________5.81

Which of the following is most consistent with these results?

A. The quality of the test results is questionable.
B. The patient has developed obstruction.
C. The patient has developed medication toxicity.
D. There is no significant change in lung function.

Answer 10

C.√ The patient has developed medication toxicity.

(u) A. The results of each test are internally valid.
(u) B. There is no evidence of obstruction.
(c) C. A decrease in DLCO is a known and common adverse reaction to bleomycin. It is the reason why serial pulmonary function tests are performed on these patients.
(u) D. This is untrue, as there is a significant decrease in the DLCO.

Question 11

40. A pulmonary function technologist is developing an asthma management plan for patient education for use in a pediatric population. Which of the following should be considered in the plan?
41. population diversity
42. literacy level
43. socioeconomic status
44. zone system settings

A. 1, 2, and 3 only
B. 1, 2, and 4 only
C. 1, 3, and 4 only
D. 2, 3, and 4 only

Answer 11

B.√ 1, 2, and 4 only

1. True. Population diversity will influence the language for delivery of the education and asthma management plan.
2. True. Literacy level impacts the selection of appropriate educational materials.
3. False. Socioeconomic status may influence access to healthcare, but does not impact the development of the educational materials or asthma management plan.
4. True. The zone system related to peak flow or symptoms is an essential component of asthma management plans.

(u) A. incorrect and incomplete
(c) B. correct
(u) C. incorrect and incomplete
(u) D. incorrect and incomplete

Question 12

44. An arterial blood gas sample is collected into a plastic syringe. To ensure the analysis of the sample is accurate, it is critical that the sample
45. contain no bubbles.
46. not be placed in ice slush.
47. be analyzed within 5 minutes.
48. be mixed before analysis.

A. 1, 2, and 3 only
B. 1, 2, and 4 only
C. 1, 3, and 4 only
D. 2, 3, and 4 only

Answer 12

B.√ 1, 2, and 4 only

1. True. The sample must not contain bubbles.
2. True. The sample should not be placed in a container with ice slush because the pO2 will be affected.
3. False. The sample does not need to be analyzed within 5 minutes, but should be analyzed within 30 minutes.
4. True. The sample must be mixed before analysis.

(u) A. incorrect and incomplete
(c) B. correct
(u) C. incorrect and incomplete
(u) D. incorrect and incomplete

Question 13

47. A 70-year-old patient’s VC is 1.4 L and FEV1 is 1.0 L. A pulmonary stress test indicates that maximum exercise V̇ F is 40 L/min. Which of the following should a pulmonary function technologist conclude?

A. The data are consistent with severe obstructive disease.
B. The results should be reported.
C. The VC is inconsistent with stress test results.
D. The FEV1 is inconsistent with stress test results.

Answer 13

B.√ The results should be reported.

(u) A. The FEV1/FVC = 0.71, which is NOT consistent with severe obstructive disease in a 70-year-old patient.
(c) B. Based on an FEV1 of 1.0 L, the expected V̇ Fmax will be approximately 35 to 40 L/min. The measured exercise ventilation is consistent with the FEV1 and should be reported as ventilatory limitation.
(u) C. The VC is not related to the expected V̇ Fmax.
(u) D. See explanation B

Question 14

54. A DLCO system that uses a gas chromatograph shows inadequate separation between the Ne and CO signals. Which of the following will correct this problem?

A. Replace the column.
B. Increase the carrier gas flow.
C. Replace the DLCO gas tank.
D. Decrease the breath-hold time.

Answer 14

A.√ Replace the column.

(c) A. Inadequate separation of the gas signals occurs when the gas chromatograph column is exhausted, and reducing the carrier gas does not solve the problem.
(u) B. Decreasing, not increasing, carrier gas flow may help to extend the useful life of the column.
(u) C. The DLCO gas does not affect the analysis of the exhaled gas.
(u) D. Decreasing breath-hold time will not change the analysis problem described.

Question 15

64. An ECG simulator is used to assess the accuracy of a 12-lead system used for exercise (stress) testing. The following ECG is recorded, including a 1-millivolt calibration signal:

See “NBRC SAE Exam - Question 64” Image

Which of the following correctly describes this simulated tracing?

A. The voltage is set to the standard ECG sensitivity.
B. The voltage is set to half-standard ECG sensitivity.
C. The simulated voltage in leads aVL and V3 is incorrect.
D. The simulated voltage in leads II and aVR is incorrect.

Answer 15

A.√ The voltage is set to the standard ECG sensitivity.

(c) A. The standard ECG sensitivity setting for a 1-millivolt calibration signal is 10 mm and is correctly displayed.
(u) B. See explanation A.
(u) C. The leads are correct as displayed. See explanation A.
(u) D. See explanation C.

Look at the calibration box on the left of the strip. It is one large box wide and 2 boxes high. This is 10mm of deflection, and the correct calibration for a 1 millivolt calibration at 25mm/sec speed.

Question 16

66. Raw results from a body plethysmograph are shown below:
\_\_\_\_\_\_\_\_\_\_\_\_\_Raw\_\_\_\_\_\_\_\_\_\_\_\_\_VTG
Trial\_\_\_\_\_(cm H2O/L/sec)\_\_\_\_\_\_\_\_\_ (L)
 1\_\_\_\_\_\_\_\_\_\_\_\_3.5\_\_\_\_\_\_\_\_\_\_\_\_\_\_4.0
 2\_\_\_\_\_\_\_\_\_\_\_2.5\_\_\_\_\_\_\_\_\_\_\_\_\_\_5.5
 3\_\_\_\_\_\_\_\_\_\_\_4.5\_\_\_\_\_\_\_\_\_\_\_\_\_\_3.0
 4\_\_\_\_\_\_\_\_\_\_\_4.5\_\_\_\_\_\_\_\_\_\_\_\_\_\_5.5

What trial results are inconsistent with the others and should be discarded?

A. 1
B. 2
C. 3
D. 4

Answer 16

D. 4

D. Trials 1, 2, and 3 all show specific conductance (1/ Raw / VTG) and resistance (Raw x VTG) values that are similar. The fourth trial shows a specific conductance and resistance that are inconsistently low.

If you don’t want to do the math, just remember that as Raw increases Vtg will decrease and vice versa. Trial 4 shows an increased Raw as well as an increased Vtg. This is inconsistent with the other trials.

Question 17

68. To have the best sensitivity for detecting obstruction in a 12-year-old female, a pulmonary function technologist should select which of the following normative values?

A. FEV1/FVC < 0.7 based on GOLD
B. FEV1/FVC < 80% predicted based on Polgar
C. FEV1/FVC < 90% predicted based on Knudson
D. FEV1/FVC < 5th percentile based on Global Lungs Initiative

Answer 17

D.√ FEV1/FVC < 5th percentile based on Global Lungs Initiative

(u) A. This may miss obstruction in a young child based on FEV1/FVC.
(u) B. See explanation A.
(u) C. See explanation A.
(c) D. The new Global Lungs Initiative equations are based on the 5th percentile as the lower limit of normal and are accurate for young children.

Question 18

73. What is the lowest recommended age for a methacholine challenge?

A. 3
B. 5
C. 8
D. 10

Answer 18

B.√ 5

B. This is the manufacturer’s recommendation for methacholine (Provocholine®).

Question 19

75. A pulmonary function technologist is setting up a metabolic measurement system for exercise. Which of the following parameters will be measured during the test?
76. resting energy expenditure
77. O2 consumption
78. CO2 production
79. MVV

A. 1 and 3 only
B. 1 and 4 only
C. 2 and 3 only
D. 2 and 4 only

Answer 19

C.√ 2 and 3 only

1. False. Resting energy expenditure is measured at rest for nutritional studies.
2. True. O2 consumption and CO2 will be measured.
3. True. See explanation 2.
4. False. MVV is part of spirometry, but is measured before exercise begins.

(u) A. incorrect and incomplete
(u) B. incorrect
(c) C. correct
(u) D. incorrect and incomplete

Question 20

79. A patient’s inspiratory capacity decreased by 0.5 L during exercise, which is most consistent with

A. lactic acidosis.
B. interstitial lung disease.
C. oxygen desaturation.
D. dynamic hyperinflation.

Answer 20

D.√ dynamic hyperinflation.

(u) A. Lactic acidosis may occur, but is not necessarily associated with dynamic hyperinflation. See explanation D.
(u) B. Lung volumes do not change due to exercise in interstitial lung disease.
(u) C. Oxygen desaturation may occur, but it is not necessarily associated with dynamic hyperinflation. See explanation D.
(c) D. Air trapping, due to closure of small airways, reduces the inspiratory capacity and expiratory flows. This causes dynamic hyperinflation.

Question 21

82. While setting up a 12-lead ECG for a cardiopulmonary exercise (stress) test, the right arm lead (RA) is accidently reversed with the left arm lead (LA). What waveform changes, if any, can be expected from this error when evaluating Lead I?

A. The T wave would be absent.
B. The P-R interval would be prolonged.
C. The QRS complex would be inverted.
D. There would be no changes in Lead II or III.

Answer 21

C.√ The QRS complex would be inverted.

(u) A. T waves would be present, but inverted. See explanation C.
(u) B. The P-R interval, along with all other intervals, would not be affected.
(c) C. The right arm is normally a negative lead and the other leads are positive.
Reversing the right and left arm would cause all of the normal waves to be inverted.
(u) D. The normal waves would be inverted in all limb leads. See explanation C.

Question 22

83. To properly measure VTG with a body plethysmograph, which of the following must be taken into account?

A. ambient room temperature
B. resistance of the shutter assembly
C. volume the patient displaces within the box
D. partial pressure of water vapor in the box

Answer 22

C.√ volume the patient displaces within the box

(u) A. Ambient temperature may affect equilibration of the temperature in the box, but it is usually allowed to settle.
(u) B. Resistance of the shutter assembly should be kept to a minimum by attentive shutter maintenance. However, the resistance of the shutter assembly is not material to proper measurement of the VTG.
(c) C. The correction for a patient’s weight may be made while the patient is in the box. However, the correction is usually made using the following formula:
[(Box volume) - (weight{kg} /1.07)] /Box volume
(where 1.07 is the assumed density of the body)
(u) D. The partial pressure of water vapor in the box is irrelevant. The partial pressure of the expired air (47 torr) is used in the equation for determining the VTG.

Question 23

84. An 80-year-old asymptomatic male is referred for an exercise (stress) test. A pulmonary function technologist observes three isolated PVCs within 1 minute during baseline. Which of the following actions is most appropriate?

A. Place the patient on 2-liter nasal cannula.
B. Obtain a 12-lead ECG.
C. Proceed with the test.
D. Reduce the planned exercise workload.

Answer 23

C.√ Proceed with the test.

(h) A. There is no indication for placing the patient on oxygen.
(a) B. Obtaining a 12-lead ECG may be an acceptable action if it does not require interruption of the test. Stress testing should be performed with a 12-lead ECG.
(c) C. With three isolated PVCs per minute, testing may continue. Complex ectopy or second- or third-degree heart block are indications for terminating the test.
(u) D. A reduction in workload is unnecessary at this time.

**If you see less than 10 PVC’s in a minute, you can proceed with a stress test.

Question 24

85. While setting up an O2 analyzer for a breath-by-breath exercise (stress) test, a pulmonary function technologist observes a delayed response. The technologist should first

A. check the CaSO4 column.
B. check for obstruction of the sample line.
C. decrease the sample flow.
D. replace the oxygen analyzer.

Answer 24

B.√ check for obstruction of the sample line.

(u) A. The CaSO4 column would not influence the analyzer phase delay.
(c) B. A delayed response is most likely secondary to an obstructed sample line.
(u) C. Decreasing the sample flow would further delay response.
(a) D. This is potentially correct, but is not the first troubleshooting action.

Question 25

87. A patient’s SVC is 4 L. The following data are obtained during a DLCO test:
    Breath-hold
    Trial_______IVC (L)_______Time (sec)________DLCO
    1_________3.95_________9.6______________24
    2_________3.90________10.2______________23
    3_________3.62________12.5______________25

According to 2017 ATS/ERS standards, results from which of the following trials should be averaged as the reported value?

A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2, and 3 only

Answer 25

A.√ 1 and 2 only

(c) A. According to 2017 ATS/ERS standards, an acceptable trial is when the IVC is 90% of VC, breath-hold time is 8 to 12 seconds, and trials are within 2.0mL/min/mm Hg. Two trials meeting this criteria should be averaged and reported as a result.

Question 26

89. A blood gas analyzer indicates a calibration failure after a cartridge change. Which of the following is the best explanation for this failure?

A. contamination of the buffers
B. expended calibration gas
C. inadequate stabilization time
D. inaccurate barometric pressure

Answer 26

C.√ inadequate stabilization time

(u) A. The solution packs are sealed, so it is highly unlikely that the buffers are contaminated.
(u) B. Calibration gases are not typically used in cartridge-based units.
(c) C. After placement of a cartridge unit, there needs to be adequate time for temperature stabilization.
(u) D. Inaccurate barometric pressure could affect the accuracy of the blood gas measurements, but would not necessarily be indicated by a calibration failure.

Question 27

90. A 61-year-old man with severe bullous emphysema presents to a pulmonary function laboratory for preoperative thoracotomy evaluation. Which of the following tests would provide the most useful information for the surgeon?

A. breathing capacity by 6-minute walk and MVV
B. oxygenation by ABG and pulse oximetry
C. muscle strength by MIP and MEP
D. lung volumes by body plethysmography and gas dilution

Answer 27

D.√ lung volumes by body plethysmography and gas dilution

(a) A. This would not provide specific information about this type of surgery for the surgeon.
(a) B. See explanation A.
(a) C. See explanation A.
(c) D. The surgeon would want to know the extent of gas trapping by the bullae. This is best measured by lung volumes by body plethysmography and gas dilution.

Question 28

92. Which of the following measurements would confirm non-invasive determination of the anaerobic threshold (AT) by the V-slope method?

A. V̇E / V̇O2 vs. V̇O2
B. VD/VT vs. V̇O2
C. PETCO2 vs. V̇O2
D. V̇E / V̇CO2 vs. V̇O2

Answer 28

A.√ V̇E / V̇O2 vs. V̇O2

(c) A. The nadir of the V̇E / V̇O2 versus V̇O2 relationship corresponds with the AT as determined by the V-slope method.
(u) B. This will help assess pulmonary gas exchange.
(u) C. This is not used to assess the AT; PETO2 vs. V̇O2 is the correct measure.
(u) D. This is not used to assess the AT; V̇E/V̇O2 vs. V̇O2 is the correct measure.

Question 29

94. Consecutive quality control runs for COHb on a hemoximeter show the following:

Expected (± 1 SD) 10.0 ± 0.1
Control run #1 10.2
Control run #2 9.9

Which of the following is the most appropriate action to take?

A. Take the instrument out of service.
B. Run protein remover.
C. Run a third control.
D. Keep the instrument in service.

Answer 29

D.√ Keep the instrument in service.

D. The controls are at or within 2 standard deviations of the expected value.

Remember, equipment is “in-control when readings remain within 2 Standard Deviations

Question 30

100. Maximum inspiratory pressure (MIP) is measured using a pressure gauge and tubing with a small leak for which of the following reasons?

A. Hypoxemia is a risk to be avoided.
B. Near RV levels cannot be maintained without some flow.
C. Negative pressure can be produced using the mouth.
D. The pressure gauge is not accurate at zero flow.

Answer 30

C.√ Negative pressure can be produced using the mouth.

(u) A. The test is of such short duration, the patient is in no danger of becoming hypoxic.
(u) B. MIP is started at RV, and the patient can maintain this volume without a small leak.
(c) C. With a small leak, pressure cannot be maintained with the mouth. This ensures that the pressure is developed by the inspiratory muscles.
(u) D. The pressure gauge measures pressure and is not affected by a small flow.

Question 31

51. The following arterial blood gas values were obtained and repeated with the same results:

 FIO2 0.21
 pH 7.39
 PaCO2 43 torr
 PaO2 81 torr
 HCO3 26 mEq/L
 BE +1 mEq/L
 SaO2 (meas) 80%

Which of the following is most consistent with these results?
A. COHb is elevated.
B. The sample was venous.
C. There was an air bubble in the sample.
D. The patient’s temperature was lower than normal.

Answer 31

A. COHb is elevated.

(c) A. For a PaO2 of 81 torr, the SaO2(meas) should be approximately 95%. COHb of 15% would account for the discrepancy between the SaO2(meas) of 80% and 95%.
(u) B. A PaO2 of 81 torr is inconsistent for venous blood.
(u) C. An air bubble could result in a PaO2 of 81 torr, but the SaO2 (meas) of 80% would represent a PaO2 of approximately 46 torr. See explanation A.
(u) D. The patient’s temperature will not affect the measurement of PaO2, which is made at 37° C (98.6° F), unless a correction is made. However, the correction would change the SaO2(meas) as well.

Note: look at the PaO2 of 81, it is a good arterial value on room air, yet the SaO2 is low. An elevated COHb is likely in this situation.

Question 32

63. Which of the following instruments will determine the oxygen saturation most accurately in a patient who has marked peripheral vasoconstriction?

A. pulse oximeter
B. transcutaneous O2 analyzer
C. end-tidal O2 analyzer
D. hemoximeter

Answer 32

D. hemoximeter

(u) A. Pulse oximetry requires a well-perfused peripheral capillary bed for an accurate assessment of SaO2.
(u) B. Transcutaneous monitors require a well-perfused capillary bed for sufficient oxygen availability for electrode sensing.
(u) C. End-tidal PO2 approximates PAO2, not SaO2.
(c) D. Arterial blood must be obtained for analysis on a hemoximeter. This circumvents the problem created by vasoconstriction when using pulse oximetry or transcutaneous methods.

Question 33

80. An arterial sample labeled "room air ABG" yields the following results at sea level:
\_\_\_\_\_\_\_Analyzer #1\_\_\_\_\_\_\_Analyzer #2
pH\_\_\_\_\_\_\_7.40\_\_\_\_\_\_\_\_\_\_\_\_\_7.42
PaCO2\_\_\_\_\_38\_\_\_\_\_\_\_\_\_\_\_\_\_\_39
PaO2\_\_\_\_\_\_120\_\_\_\_\_\_\_\_\_\_\_\_ 122

In this situation, a pulmonary function technologist should

A. report the average of each value.
B. inquire about the FIO2.
C. question the results from analyzer #2.
D. run quality control on analyzer #1.

Answer 33

B. inquire about the FIO2.

Remember to calculate!! A couple things to note here:

Normal PaO2 on room air is 80-100.

If you do the AA equation you will see that the PaO2 result is lower than what your PAO2 is on the blood gas. This would lead to a negative A-a gradient. The patient is on supplemental O2.

(u) A. Blood gas results should not be averaged. See explanation B.
(c) B. Calculating the A-a gradient from analyzer 1 and 2 both reveal gradients that are not consistent with an oxygen fraction of room air; therefore, the FIO2 should be questioned.
(u) C. See explanation B.
(u) D. See explanation B.