Deck 19: Analysis and Monitoring of Gas Exchange

Question 1

Which of the following is false about the galvanic fuel cell O₂ analyzer?

A) It actually measures the PO₂ and not the O₂ concentration.
B) It requires an external power source (alternating current line or batteries).
C) It has a slower response time than the Clark electrode.
D) Its fuel cells deplete and must be periodically replaced.

Answer 1

B
Explanation: Most galvanic fuel cells use a gold anode and a lead cathode. Unlike the Clark electrode, current flow across these poles is generated by the chemical reaction itself. Thus, unless accessories such as alarms are included, a galvanic cell needs no external power. Unfortunately, this means that galvanic cells respond more slowly than do Clark electrodes, sometimes taking as long as 60 sec.

Question 2

Which of the following should be monitored during the sampling of arterial blood?
1) Blood pressure proximal to puncture site
2) Presence of pulsatile blood return
3) Presence of air bubbles or clots in sample
4) Appearance of puncture site

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

Answer 2

B

Question 3

Purposes of a needle-capping device include which of the following?
1) To isolate the sample from air exposure
2) To help prevent needlestick injuries
3) To hold the excess anticoagulant

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

Answer 3

A

Question 4

After obtaining an arterial blood sample through percutaneous puncture using a syringe that does not have a capping safety device, what should you do?

A) Remove the needle with a Kelly clamp, then plug the syringe.
B) "Scoop" the needle cap up with one hand, then plug the syringe.
C) Force the needle into a rubber cork or plastic stopper.
D) Manually remove and bend the needle, then plug the syringe.

Question 5

You are asked to provide continuous monitoring of the FiO₂ provided by a humidified O₂ delivery system using a galvanic cell analyzer. Where would you install the analyzer's sensor?

A) Proximal to the heated humidifier
B) On the expiratory side of the circuit
C) Distal to the heated humidifier
D) As close to the patient as possible

Question 6

Clinical indications for arterial blood analysis include which of the following?
1) Sudden, unexplained dyspnea
2) Cardiopulmonary resuscitation
3) Changes in ventilator settings
4) Chest pain

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

Question 7

How does the Clark polarographic O₂ electrode function?

A) It measures the magnetic properties of O₂ versus N_2.
B) It measures the electrical potential across a Wheatstone bridge.
C) It uses O₂ to produce a reduction-oxidation reaction.
D) It measures the comparative cooling effect on a heated wire.

Question 8

Which of the following are true about invasive versus noninvasive monitoring?

Question 9

Which of the following sites are used for arterial blood sampling by percutaneous needle puncture?
1) Femoral
2) Radial
3) Brachial
4) Carotid

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

Question 10

While checking a polarographic (Clark) electrode, you determine that the device fails to read 100% when exposed to pure O₂. Which of the following actions would be the proper first step?

A) Check the silica crystals.
B) Send the device out for repair.
C) Replace the analyzer's batteries.
D) Change the analyzer's fuel cell.

Question 11

Precautions and/or possible complications of arterial puncture include which of the following?
1) Arteriospasm
2) Embolization
3) Infection
4) Hemorrhage

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

Question 12

Physiologic monitoring can be either invasive or noninvasive.

Question 13

Under ideal conditions, electrochemical oxygen (O₂) analyzers have approximately what degree of accuracy?

A) 1%
B) 2%
C) 3%
D) 4%

Question 14

Why is the radial artery the preferred site for arterial blood sampling?
1) It is near the surface and easy to palpate and stabilize.
2) The ulnar artery normally provides good collateral circulation.
3) The radial artery is not near any large veins.
4) It is the largest artery located in the upper extremities.

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

Question 15

During calibration of a Clark polarographic O₂ analyzer, you cannot get the sensor to read 100% when exposed to 100% O₂, even after adjusting its calibration control. The unit has new batteries. Which of the following actions would be correct?

A) Use it only with low FiO₂ values.
B) Send the device out for repair.
C) Replace the unit's batteries.
D) Change the sensor or electrode.

Question 16

Invasive procedures provide more accurate data but carry greater risks.

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

Question 17

Which of the following are reasons for finding an alternative site for arterial puncture?
1) Failed Allen test
2) History of peripheral vascular disease
3) Anticoagulation therapy
4) Presence of a surgical shunt

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

Question 18

Which of the following patient parameters does not need to be assessed as part of arterial blood sampling?

A) Blood pressure
B) Temperature
C) Position or activity level
D) Clinical appearance

Question 19

If patient pain or anxiety occurs during arterial puncture, which of the following will probably occur?

A) Hypoventilation
B) Hyperventilation
C) Respiratory acidosis
D) Hypoxemia

Question 20

What chart information should be checked before performing artery puncture?
1) Patient's primary diagnosis and history
2) Presence of bleeding disorders or blood-borne infections
3) Anticoagulant or thrombolytic drug prescriptions
4) Respiratory care orders (e.g., O₂ therapy)

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

Question 21

After obtaining an arterial blood sample, what should you do?
1) Apply pressure to the puncture site until bleeding stops.
2) Place the sample in a transport container with ice slush.
3) Check to see if the patient is getting anticoagulant therapy.
4) Mix the sample by rolling and inverting the syringe.

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

Question 22

Invasive procedures require insertion of a device into the body.

Question 23

Which of the following indicates venous admixture during arterial puncture?
1) Need to use syringe suction.
2) Dark-colored blood.
3) Small sample volumes.

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

Question 24

Laboratory analysis of gas exchange is usually noninvasive in nature.

Question 25

How long should you wait before drawing an ABG on a chronic obstructive pulmonary disease (COPD) patient whose FiO₂ has just been changed?

A) 5 to 10 min
B) 10 to 15 min
C) 15 to 20 min
D) 20 to 30 min

Question 26

Most pre-analytical ABG errors can be avoided by ensuring that the sample is which of the following?
1) Properly anticoagulated.
2) Obtained anaerobically.
3) Analyzed within 15 to 30 min.

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

Question 27

Which of the following describes the correct procedure for an Allen test?

A) Compress both the radial and ulnar arteries, and then release the radial artery.
B) Compress both the radial and ulnar arteries, and then release the ulnar artery.
C) Compress both the radial and ulnar arteries, and then release both arteries at once.
D) Compress the brachial artery only and observe circulation to the hand.

Question 28

Required equipment and supplies for percutaneous arterial blood sampling of an adult include all of the following except:

A) antiseptic (alcohol or Betadine).
B) patient or sample label.
C) 20- to 22-gauge needle.
D) local anesthetic.

Question 29

Which of the following would you expect to occur if too much heparin was used in gathering an ABG sample from a patient breathing room air?

A) Increase in HCO₃^-
B) Decrease in PCO₂
C) Decrease in pH
D) Decrease in PO₂

Question 30

Which of the following Centers for Disease Control and Prevention (CDC) barrier precautions would you use when obtaining an arterial blood gas (ABG) through percutaneous puncture?
1) Gloves
2) Protective eyewear
3) Gown or apron

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

Question 31

When performing an Allen test on the left hand of a patient, you notice that the palm, fingers, and thumb remain blanched for more than 15 sec after pressure on the ulnar artery is released. What should you do?

A) Use the brachial site for sampling.
B) Sample from the contralateral radial artery.
C) Use the femoral site for sampling.
D) Perform the Allen test on the right hand.

Question 32

You are asked to calibrate an O₂ analyzer. Which of the following gases would you use for this procedure?
1) 100% oxygen
2) 50% oxygen
3) 21% oxygen (room air)

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

Question 33

To avoid the dilution effects caused by too much sodium heparin during ABG sampling of an adult, what should you do?
1) Ensure a sample volume greater than 2 ml.
2) Use dry heparin instead.
3) Fill the needle dead space only.
4) Use saline if dry heparin is not available.

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

Question 34

When analyzing an ABG sample from a patient with acute respiratory distress syndrome and refractory hypoxemia, you notice a PaO₂ of 141 mm Hg and a PaCO₂ of 14 mm Hg. Which of the following analytic errors should you suspect?

A) Excessive time since sample collection
B) Exposure of the blood sample to air
C) Excessive heparin in the sample
D) Sample admixture with venous blood

Question 35

You return to a patient's room 20 min after drawing an ABG. Which of the following should you check at this time?
1) Puncture site for hematoma
2) Adequacy of distal circulation
3) Prothrombin or partial thromboplastin times

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

Question 36

What size needle would you recommend to obtain an ABG sample through percutaneous puncture of an infant?

A) 18 gauge
B) 20 gauge
C) 22 gauge
D) 25 gauge

Question 37

A patient suffering from traumatic brain injury in the ICU has a PtO₂ (tissue oxygen) value of 10 to 15 mm Hg, what does this indicate?

A) Normal intracranial pressure
B) Ischemic brain damage
C) Normal cerebral perfusion
D) Cerebral hyperperfusion

Question 38

When performing a percutaneous needle puncture of the radial artery, you get only a small spurt of blood. Which of the following is the best action at this time?

A) Slowly withdraw the needle until a pulsatile flow fills the syringe.
B) Pull out entirely, use a different angle and then reinsert it.
C) Slowly advance the needle until a pulsatile flow fills the syringe.
D) Repeat the procedure with a fresh blood gas kit.

Question 39

A practitioner forgets to ice an ABG sample and leaves it at room temperature for 45 min. Which of the following parameters can you predict will increase in this sample during that period?
1) PCO₂
2) pH
3) PO₂

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

Question 40

Before performing puncture or cannulation of the radial artery, what should you do?

A) Fix and tighten a tourniquet above the antecubital fossa.
B) Perform the Allen test to ensure collateral circulation.
C) Inject heparin into the adjoining subcutaneous tissues.
D) Apply firm pressure to the arterial site for 5 min.

Question 41

A PaO₂ below what value would be considered moderate hypoxemia?

A) 75 mm Hg
B) 65 mm Hg
C) 55 mm Hg
D) Depends on the FiO₂

Question 42

Which of the following changes would occur if an arterial blood sample of a patient breathing room air were exposed to a large air bubble?
1) Decreased PCO₂
2) Decreased pH
3) Increased PO₂

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

Question 43

An outpatient scheduled for an arterial blood sample enters the pulmonary lab 20 min late and out of breath, having run up four flights of stairs. What should you do?

A) Postpone the blood sample until tomorrow.
B) Scold the patient for being so late.
C) Wait 5 min before taking the sample.
D) Scold the patient for using the stairs.

Question 44

A physician requests that you obtain and set up an arterial line system for invasive monitoring of blood pressure. Which of the following equipment would you gather?
1) Pressurized intravenous bag
2) Continuous flush device
3) Arterial catheter
4) Volume transducer

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

Question 45

Because of an extremely low PO₂, you suspect that an arterial blood sample taken from a patient's brachial artery might have been contaminated with venous blood. Which of the following might help to confirm your suspicion?

A) Call the laboratory resources/staff to get the latest chemistry report.
B) Inspect the sample for color and consistency.
C) Cross-check the sample with an SpO₂ reading.
D) Measure the sample's actual hemoglobin saturation.

Question 46

A mixed venous blood sample obtained from a pulmonary artery catheter sample has a PO₂ of 85 mm Hg and a hemoglobin saturation of 95%. Which of the following is likely?
1) The pulmonary artery catheter balloon was not deflated.
2) The sample was drawn from the proximal, not distal port.
3) The blood sample was withdrawn too quickly.

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

Question 47

What is a normal level for CaO₂?

A) 12 to 15 ml/100 ml
B) 14 to 16 ml/100 ml
C) 18 to 20 ml/100 ml
D) 16 to 22 ml/100 ml

Question 48

All of the following are true about capillary blood gas sampling except:

A) capillary sampling can be used in lieu of direct arterial access in some infants and small children.
B) a capillary sample PO₂ provides a fairly close estimate of actual arterial oxygenation.
C) clinicians should exercise caution when using capillary samples to guide decisions.
D) properly obtained capillary blood can provide estimates of arterial pH and PCO₂ levels.

Question 49

Which of the following can help avoid the problem of arterial blood sample contamination with air?
1) Discarding frothy samples
2) Fully expelling any bubbles
3) Mixing before expelling air
4) Capping syringe quickly

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

Question 50

Through which pulmonary artery catheter port would you obtain a mixed venous blood sample?

A) Proximal (right atrium) port
B) Catheter thermistor connector
C) Distal (catheter tip) port
D) Balloon inflation port

Question 51

What is the best site for capillary puncture in an infant?

A) Lateral aspect of the heel's plantar surface
B) Anterior curvature of the heel
C) Medial aspect of the heel's plantar surface
D) Posterior curvature of the heel

Question 52

After obtaining an arterial blood sample from an arterial line, you would do all of the following except:

A) flush the line and stopcock with the heparinized intravenous solution.
B) aspirate at least 5 ml of fluid or blood (dead space or waste).
C) confirm stopcock port open to intravenous bag solution and catheter.
D) confirm undamped pulse pressure waveform on monitor.

Question 53

Possible complications of capillary blood gas sampling include which of the following?
1) Infection
2) Hematoma
3) Hemorrhage
4) Hypotension

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

Question 54

When is capillary blood gas sampling indicated?

A) There is a need for direct analysis of blood oxygenation.
B) Normal noninvasive monitor readings need to be checked.
C) ABG analysis is needed, but arterial access is not available.
D) Continuous data on patient ventilation status are needed.

Question 55

Analysis of an arterial blood sample taken from a healthy athlete reveals a pH of 7.36, a PCO₂ of 45 mm Hg, and a PO₂ of 43 mm Hg. Which of the following analytic errors should you suspect?

A) Excessive time since sample collection
B) Exposure of the blood sample to air
C) Excessive heparin in the sample
D) Sample admixture with venous blood

Question 56

Capillary puncture should be performed at or through what location?
1) Edematous tissue
2) Areas with new signs of infection
3) The heal of neonates
4) Previous puncture sites

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

Question 57

Before connecting the sample syringe to an adult's arterial line stopcock, what would you do?

A) Flush the line and stopcock with the heparinized intravenous solution.
B) Aspirate 1 to 2 ml of fluid or blood using a waste syringe.
C) Align the stopcock off to the patient and on to the flush solution.
D) Increase the flush-solution bag pressure by 20 to 30 mm Hg.

Question 58

To assess gas exchange at the tissues, you would obtain a blood sample from which of the following?

A) Pulmonary artery (balloon-deflated)
B) Peripheral artery (radial, brachial)
C) Central vein (superior or inferior vena cava)
D) Pulmonary artery (balloon-inflated)

Question 59

Warming a capillary bed to 42° C has which of the following effects?
1) It constricts the underlying blood vessels.
2) It increases blood flow well above tissue needs.
3) It "arterializes" the capillary blood.

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

Question 60

You determine that a blood gas sample that requires analysis has been sitting in ice slush for 90 min. What should you do?

A) Go ahead and analyze the sample (because it was on ice).
B) Warm the sample to room temperature before analysis.
C) Readjust the blood gas analyzer temperature to 0° C.
D) Discard the sample and notify the appropriate clinician.

Question 61

The advantage that point-of-care testing has over traditional laboratory testing is that point-of-care testing:

A) reduces turnaround time.
B) utilizes equipment that is less expensive.
C) does not require trained personnel to run the tests.
D) is more accurate than traditional laboratory testing.

Question 62

Which of the following are true about a blood gas analyzer's waste fluids?
1) A strong disinfectant should be added to waste fluid containers.
2) Waste fluids should be handled as if they were blood samples.
3) Waste fluids should be treated as potentially infectious.

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

Question 63

Which blood gas analyzer electrode uses a separate reference electrode?

A) O₂
B) pH
C) Clark
D) HCO₃^-

Question 64

The total instrument error (inaccuracy) of a blood gas analyzer equals which of the following?

A) Bias + imprecision
B) Imprecision + random error
C) Bias + systematic error
D) Trend error + bias

Question 65

What media are used to calibrate a blood gas analyzer's gas electrodes?

A) Standard pH buffer solutions
B) Bloodlike control media
C) Precision mixtures of O₂ and CO₂
D) Tonometered human blood samples

Question 66

Statistically derived limits for internal quality control of blood gas samples are usually set at what appropriate level?

A) 1 standard deviation from the mean
B) 2 standard deviations from the mean
C) 3 standard deviations from the mean
D) 5 standard deviations from the mean

Question 67

Which of the following factors contributing to imprecision (random) errors during blood gas analysis?

A) Sample contamination
B) Contaminated buffers
C) Statistical probability
D) Sample mishandling

Question 68

Which of the following factors does not contributing to bias (systematic) errors during blood gas analysis?

A) Incorrect procedures
B) Statistical probability
C) Contaminated buffers
D) Component failure

Question 69

What is the quality control procedure of analysis and reporting on externally provided control media with unknown values?

A) Automated calibration
B) Performance validation
C) Proficiency testing
D) Preventive maintenance

Question 70

When inspecting an internal quality-control plot for a blood gas analyzer, you notice several data points sporadically appearing outside the 2 standard deviation (SD) range. This represents what type of analytic error?
1) Random error
2) Bias
3) Imprecision
4) Systematic error

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

Question 71

When analyzing a blood gas control sample, you notice that the result falls outside the 2 SD range. How could you verify that this was a random error (error of imprecision)?
1) Repeat the analysis on a different analyzer.
2) Compare the control to an actual patient sample.
3) Rerun the control sample a second time.

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

Question 72

What is the process of testing a new blood gas analyzer to confirm a manufacturer's claims?

A) Automated calibration
B) Performance validation
C) Proficiency testing
D) Preventive maintenance

Question 73

To measure PCO₂, blood gas analyzers use what electrode?

A) Severinghaus
B) Clark
C) Sahn
D) White

Question 74

While analyzing a blood gas control sample, you notice a trending of several PCO₂ values above the 2 SD range over the last six control samples run. What corrective action would you consider at this time?
1) Check the function of the PCO₂ electrode.
2) Rerun the control sample a second time.
3) Repair or replace any failed components.

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

Question 75

How is the accuracy of a blood gas analyzer determined?

A) Examining the repeatability of the analyzer's results
B) Comparing the analyzer's measurements to known values
C) Adjusting the offset (or balance) of the instrument
D) Adjusting the gain (or slope) of the instrument

Question 76

Before a sample of capillary blood is taken, what should you do to the site?
1) Warmed to 42° C for 10 min.
2) Squeezed lightly until blanched.
3) Cleaned with an antiseptic solution.

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

Question 77

How often should blood gas calibration verification by control media take place?

A) At least one level of control media should be analyzed every 8 hr.
B) At least two levels of control media should be analyzed every day.
C) At least two levels of control media should be analyzed every 8 hr.
D) At least two levels of control media should be analyzed every hour.

Question 78

A blood gas analyzer measures which of the following?
1) HCO₃^-
2) PCO₂
3) PO₂
4) pH

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

Question 79

Components of a laboratory blood gas analyzer include which of the following?
1) Two-electrode measuring chamber
2) Reagent containers
3) Calibrating gas tanks
4) Waste container

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

Question 80

To ensure that the output of a blood gas analyzer is both accurate and linear across the range of measured values, a calibration procedure must measure what?

A) Two different parameters at the same time
B) Parameters with known input values at one point
C) Two different parameters at different times
D) Parameters with known input values at two points