Question 1

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

Accepted Answer

In COPD patients, it is recommended to wait 20 to 30 minutes after changing the FiO2 to allow the patient's blood gases to stabilize before drawing an arterial blood gas (ABG) sample.

Question 2

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.

Accepted Answer

Most pre-analytical errors in arterial blood gas (ABG) analysis can be avoided by ensuring the sample is properly anticoagulated to prevent clotting, obtained anaerobically to avoid contamination with air which can alter gas measurements, and analyzed within 15 to 30 minutes to ensure the accuracy of the results before any significant changes in gas composition can occur.

Question 3

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

Accepted Answer

During an Allen test, both the radial and ulnar arteries are compressed and then the ulnar artery is released while continuing to compress the radial artery. This allows for assessment of collateral circulation to the hand. Option A releases the wrong artery first, while option C releases both arteries at once, making it difficult to assess collateral flow. Option D is not the correct procedure for an Allen test.

Question 4

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

Accepted Answer

All of the other options listed (antiseptic, patient or sample label, and a 20- to 22-gauge needle) are necessary for performing a percutaneous arterial blood sample on an adult. Local anesthetic is not usually required, as the puncture site is typically small and superficial. However, some medical practitioners may choose to use a topical anesthetic cream or cooling spray to reduce discomfort for the patient.

Question 5

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?

Accepted Answer

Excess heparin can dilute the blood sample, leading to a decrease in PCO₂ as CO₂ diffuses out of the blood into the heparin solution.

Question 6

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

Accepted Answer

When obtaining an arterial blood gas (ABG) through percutaneous puncture, gloves and protective eyewear are recommended to protect against blood splashes and contact with blood. A gown or apron is not specifically required for this procedure unless there is an anticipated risk of blood or bodily fluid splashes beyond what gloves and eyewear can protect against.

Question 7

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?

Accepted Answer

Performing the Allen test on the right hand will help determine if the patient has adequate collateral circulation in the other hand, which is necessary before proceeding with arterial sampling from the radial artery.

Question 8

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)

Accepted Answer

The O₂ analyzer is typically used to measure oxygen concentration in gases, so 100% oxygen would be the best choice for calibration. However, it is also important to calibrate the analyzer in room air, which contains 21% oxygen, to ensure accurate measurements in real-world conditions. Using 50% oxygen would not be necessary or helpful in this calibration procedure. Therefore, the best choice(s) would be 1 and 3 only (options A and C are incorrect).

Question 9

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.

Accepted Answer

Using dry heparin reduces the risk of dilution, ensuring a sample volume greater than 2 ml minimizes the relative amount of heparin, and filling only the needle dead space with heparin helps avoid excess heparin in the sample.

Question 10

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?

Accepted Answer

The PaO2 and PaCO2 values in this sample suggest exposure to air, a common error that can occur during sample collection or handling. Excessive time since sample collection (A) could lead to decreased PaO2 and increased PaCO2, but not to the values observed in this patient. Excessive heparin (C) would affect the coagulation status of the blood but not the gas values. Sample admixture with venous blood (D) would cause a mixed venous-arterial blood gas result, with a lower PaO2 and higher PaCO2 than observed in this case.

Question 11

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

Accepted Answer

Checking the puncture site for hematoma is important to ensure that the patient is not experiencing any bleeding or swelling that could lead to complications such as infection or occlusion of the vessel. Adequacy of distal circulation should also be assessed to ensure proper blood flow to the extremity. However, checking prothrombin or partial thromboplastin times at this time is not necessary or relevant to the immediate care of the patient.

Question 12

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

Accepted Answer

A 25 gauge needle is recommended for obtaining an arterial blood gas (ABG) sample in infants to minimize trauma and ensure precision.

Question 13

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?

Accepted Answer

In patients with traumatic brain injury, brain tissue oxygen (PtO₂) values when intracranial pressure and cerebral perfusion are normal are between 25 and 30 mm Hg. The critical threshold for ischemic brain damage and poor outcome is suspected to be around a brain PtO₂ of 10 to 15 mm Hg.

Question 14

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?

Accepted Answer

If you get only a small spurt of blood, the needle has probably passed through the artery. In this situation, slowly withdraw the needle until a pulsatile flow fills the syringe.

Question 15

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

Accepted Answer

PCO₂ will increase because cellular metabolism continues in the blood sample, producing CO₂.

Question 16

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

Accepted Answer

Before performing puncture or cannulation of the radial artery, it is important to perform the Allen test to ensure that there is adequate collateral circulation in the hand. This is done by compressing both the ulnar and radial arteries and having the patient make a fist. Then, one artery is released while observing the color and filling of the palm. If the palm remains well-perfused, it indicates that the released artery has adequate collateral circulation and is safe for puncture or cannulation. This is important to prevent ischemia or damage to the hand.

Question 17

A PaO₂ below what value would be considered moderate hypoxemia?

Accepted Answer

The answer of A PaO₂ below what value would be...

Question 18

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

Accepted Answer

The answer of Which of the following changes would occur...

Question 19

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?

Accepted Answer

The answer of An outpatient scheduled for an arterial blood...

Question 20

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

Accepted Answer

The answer of A physician requests that you obtain and...

Quiz 19: Analysis and Monitoring of Gas Exchange

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

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.

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

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

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?

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

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?

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)

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.

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?

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

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

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?