Chapter 19 Analysis and Monitoring of Gas Exchange

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.

"Scoop" the needle cap up with one hand, then plug the syringe.

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

1 and 2 only

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

1 and 2 only

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

1 and 2 only

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

1 and 3 only

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

1 and 3 only

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

1 and 3 only

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

1 and 3 only

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

1 and 3 only

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

1 and 3 only

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

1 only

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

1, 2, 3, and 4

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

1, 2, 3, and 4

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

1, 2, and 3

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

1, 2, and 3

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

1, 2, and 3 only

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

1, 2, and 3 only

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

1, 2, and 3 only

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

1, 2, and 3 only

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

1, 2, and 4 only

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

1, 2, and 4 only

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

1, 2, and 4 only

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

2, 3, and 4 only

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

18 to 20 ml/100 ml

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

2, 3, and 4 only

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

2, 3, and 4 only

After changing the FiO2 of a patient with emphysema, how long should you wait to draw an ABG to monitor the patient's respiratory status? a. 5 to 10 min b. 10 to 20 min c. 20 to 30 min d. 30 to 40 min

20 to 30 min

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

20 to 30 min

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

55 mm Hg

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.

At least two levels of control media should be analyzed every 8 hr.

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

Decrease in PCO2

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

Bias + imprecision

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

Blood pressure

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

Comparing the analyzer's measurements to known values

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.

Compress both the radial and ulnar arteries, and then release the ulnar artery.

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

Contaminated buffers

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 SpO2reading. d. Measure the sample's actual hemoglobin saturation.

Cross-check the sample with an SpO2reading.

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. Read just the blood gas analyzer temperature to 0° C. d. Discard the sample and notify the appropriate clinician.

Discard the sample and notify the appropriate clinician.

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

Exposure of the blood sample to air

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

Hyperventilation

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

Parameters with known input values at two points

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.

Perform the Allen test on the right hand.

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.

Perform the Allen test to ensure collateral circulation.

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

Precision mixtures of O2 and CO2

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

Proficiency testing

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

Sample admixture with venous blood

To measure PCO2, blood gas analyzers use what electrode? a. Severinghaus b. Clark c. Sahn d. White

Severinghaus

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.

Slowly withdraw the needle until a pulsatile flow fills the syringe.

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

Statistical probability

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.

Wait 5 min before taking the sample.

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.

local anesthetic.

Which blood gas analyzer electrode uses a separate reference electrode? a. O2 b. pH c. Clark d. HCO3-

pH