Arterial Blood Gas and Metabolism Quiz

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Questions and Answers

What does the arterial blood gas (ABG) primarily measure regarding the body's acid/base status?

Bicarbonate levels (correct)

Body temperature

Ventilation adequacy

Dissolved oxygen levels

Which component of arterial blood gases indicates the adequacy of ventilation?

PaO2

PaCO2 (correct)

HCO3

What is the role of bicarbonate (HCO3) in the body?

A byproduct of fat metabolism

The body's largest acid buffer system (correct)

A primary energy source

A component of oxygen transport

Which method is considered the gold standard for assessing oxygenation and acid-base disorders?

Arterial blood gas (ABG) Signup and view all the answers

What is the primary function of catabolism within metabolism?

Destruction of complex molecules Signup and view all the answers

What does the VBG reliably assess in a clinical situation?

pH and HCO3 Signup and view all the answers

Which process is involved in the transformation of complex saccharides into glucose in the liver?

Glycogenolysis Signup and view all the answers

Which factors can alter the pH in the body?

Metabolic and respiratory components Signup and view all the answers

What factor can potentially increase both PT and INR in a patient?

Liver damage Signup and view all the answers

How long should a patient ideally stabilize before an arterial blood gas (ABG) sample is taken after a therapeutic intervention?

15-20 minutes Signup and view all the answers

What effect does a decrease in body temperature have on PaCO2 levels?

Decrease in PaCO2 Signup and view all the answers

What is a common error that can occur if air bubbles are introduced into an ABG sample?

PaO2 will rise to atmospheric levels Signup and view all the answers

What could a prolonged time (over 30 minutes) before testing an ABG sample lead to?

Decreased pH and increased PaCO2 Signup and view all the answers

What laboratory test measures a patient's intrinsic clotting pathway?

aPTT Signup and view all the answers

What is a potential consequence of heparin dilution in an ABG sample?

Decrease in PaCO2 and increase in pH Signup and view all the answers

What happens to excess blood glucose when levels are abnormally high?

It is stored in muscle as glycogen. Signup and view all the answers

Which of the following factors is NOT a consideration for proper ABG sampling?

Patient's weight Signup and view all the answers

What role do proteins play in the body?

They are essential for hormonal functions and tissue repair. Signup and view all the answers

Which statement about lipid metabolism is true?

Lipids provide structural support and act as energy stores. Signup and view all the answers

What is the respiratory quotient (RQ) for carbohydrate metabolism?

1.0 Signup and view all the answers

How much ATP is produced from the complete oxidation of glucose in the presence of oxygen?

38 ATP Signup and view all the answers

What does anaerobic metabolism primarily produce?

Lactic acid and ATP Signup and view all the answers

Where is ATP primarily produced within the cell?

In the mitochondria Signup and view all the answers

What condition can result from the formation of ketone bodies in the absence of sufficient glucose?

Metabolic acidosis Signup and view all the answers

What is the primary reason for ensuring a sample is adequately heparinized during arterial blood gas sampling?

To prevent clot formation in the sample. Signup and view all the answers

How much blood is typically required for an adequate arterial blood gas sample in adults?

1.5-3 mL Signup and view all the answers

What is the formula for calculating total oxygen content in the blood?

Hb x SaO2 x 1.34 mL/O2/g Hb + (0.003 mL O2/100 mL of blood/mmHg) Signup and view all the answers

What effect does 2,3 Diphosphoglycerate (DPG) have on hemoglobin?

Decreases hemoglobin's affinity for oxygen. Signup and view all the answers

Which shift in the oxyhemoglobin dissociation curve indicates a decreased affinity of hemoglobin for oxygen?

Right shift Signup and view all the answers

What proportion of fetal hemoglobin is typically present in a term infant at birth?

80% Signup and view all the answers

Which of the following describes carboxyhemoglobin?

Hemoglobin that binds carbon monoxide with greater affinity than oxygen. Signup and view all the answers

Which statement about normal hemoglobin levels is accurate?

Normal hemoglobin levels for women range from 13-14 g/100 mL. Signup and view all the answers

Study Notes

Arterial Blood Gas (ABG)

ABG aids in diagnosis, assessment, and treatment by providing information on pH, PaCO2, PaO2, HCO3, and oxygen saturation in arterial blood.
pH indicates the body's acid/base status.
PaCO2 reflects ventilation adequacy.
PaO2 measures the amount of oxygen dissolved in the blood and correlates to the SpO2.
HCO3 represents bicarbonate, a significant acid buffer system managed by the kidneys.
VBG can be a reliable alternative for assessing pH, PvCO2, and HCO3, but its accuracy can be affected by local metabolism and variability in unstable patients.
ABG is the gold standard for assessing and managing oxygenation and acid-base disorders.

Metabolism

Metabolism is the sum of chemical processes in the body, resulting in growth, energy generation, and other bodily functions.
Catabolism breaks down complex molecules to create energy.
Anabolism builds complex molecules from simpler ones, requiring energy.

Carbohydrates

Primary energy source, readily absorbed into the bloodstream.
Simple sugars are absorbed as glucose, complex saccharides require glycogenolysis to transform into glucose in the liver.
Gluconeogenesis in the liver produces glucose from pyruvic acid, lactic acid, amino acids, and glycerol.
Excess blood glucose is excreted in the urine, converted to fat, or stored as glycogen.

Protein

Essential for tissue growth, repair, and maintenance.
Provides building blocks for RNA, DNA, and enzymes.
Involved in hormonal function.
Absorbed as amino acids and synthesized by the liver.
Protein oxidation produces CO2, H2O, energy, and urea.

Lipids

Energy stores, signaling molecules, and structural components of cell membranes.
Absorbed from the intestine or synthesized from glucose, pyruvic acid, and amino acids.
Lipid breakdown produces ketone bodies, which can lead to metabolic acidosis.

Respiratory Quotient (RQ)

Reflects the volume of CO2 produced per volume of O2 consumed.
Carbohydrate metabolism RQ is 1.0.
Fat metabolism RQ is 0.7.
Protein metabolism RQ is 0.8.
Whole-body RQ is 0.8.

ATP

Primary and most usable form of energy in the body.
Produced in the mitochondria.
Powers enzymatic reactions, muscle contractions, and metabolic functions.
Complete glucose oxidation with oxygen yields 38 ATP molecules.

Citric Acid Cycle (Krebs Cycle)

Oxidative phosphorylation process resulting in complete glucose oxidation.
Requires oxygen to produce 38 ATP.
Anaerobic metabolism produces lactic acid, reducing HCO3 buffering capacity.

Arterial Blood Gas Sampling

Requires a steady state for accurate interpretation.
Ideally, wait 15-20 minutes after interventions for stabilization.
Consider patient temperature during interpretation.

ABG Sampling Errors

Air bubbles: PaCO2 tends toward zero, PaO2 rises to atmospheric levels.
Delayed testing (over 30 min): Increased PaCO2, decreased pH, decreased PaO2.
Heparin dilution: Decreased PaCO2 and pH.
Venous sampling: Values do not reflect arterial blood.

Avoiding ABG Sampling Errors

Choose a bounding artery with a strong, palpable pulse.
Verify saturations with oximetry.
Utilize proper needle size.
Ensure adequate heparinization.
Position the patient correctly.
Obtain a sufficient sample size.

Oxygen Transport

Oxygen in the blood is transported in two ways:
- Dissolved in blood plasma (0.003 mL O2/100 mL of blood/mmHg)
- Bound to hemoglobin (1.34 mL O2/g of Hb at 100% saturation)
Total oxygen content is the sum of dissolved and combined oxygen.

Hemoglobin

Each red blood cell contains about 280 million hemoglobin molecules.
Heme group binds to oxygen molecules, allowing each hemoglobin molecule to carry four oxygen molecules.
Normal hemoglobin levels:
- Men: 15 g/100 mL
- Women: 13-14 g/100 mL

Oxyhemoglobin Dissociation Curve

Illustrates the relationship between the partial pressure of oxygen (PaO2) and hemoglobin saturation.
Shifts in the curve reflect changes in hemoglobin's affinity for oxygen.

Shifts of the Curve

Left shift: Increased affinity, better oxygen delivery to tissues.
Right shift: Decreased affinity, less oxygen delivery to tissues.

2,3 Diphosphoglycerate (DPG)

Organic phosphate group in erythrocytes.
Binds to hemoglobin, reducing its affinity for oxygen.
A rapid compensatory mechanism.

Hemoglobin Variants and Abnormalities

Fetal hemoglobin: Higher affinity for oxygen than adults.
Carboxyhemoglobin: CO binds to hemoglobin, preventing oxygen binding, resulting in reduced oxygen-carrying capacity.

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Description

Test your knowledge on Arterial Blood Gas (ABG) and metabolism concepts. This quiz covers important parameters like pH, PaCO2, HCO3, and their significance in diagnostics. Additionally, explore how metabolism interacts with energy generation and bodily functions through catabolism and anabolism.