Acid Base Balance ABG NCLEX Questions with Rationale

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NCLEX Acid Base Balance ABG Questions

Acid Base Balance ABG NCLEX Questions Test Strategies

1.  A nurse needs to know the acid-base balance of a patient for which ABG test can be helpful.
2. ABG test involves measuring PH, PaCO₂, HCO₃, oxygen saturation (O₂ Sat), and PaO₂.
3. PH determines if it is an acidotic or alkalotic condition.
4. PaCO₂ measures carbon dioxide in blood, which indicates respiratory acidosis or alkalosis.
5. HCO₃ acts as a buffer in maintaining PH.
6. O₂ Sat measures the percentage of oxygen bound to hemoglobin, and the normal range is 94-100%.
7. PaO₂ shows the combining capacity of oxygen with hemoglobin, and the normal range is 80-100 mmHg.
8. Oxygen content and oxygen saturation are different concepts.
9. Normal ranges for ABG parameters are: PH (7.35-7.45), PaCO₂ (35-45 mmHg). HCO₃ (22-26 mEq/L), O₂ Sat (94-100%), and PaO₂ (80-100 mmHg).
10. Metabolic acidosis: Decreased PH, PCO₂. and decreased bicarbonate
11. Metabolic alkalosis: Elevated PH, PCO₂, and bicarbonate
12. Respiratory acidosis: Decreased PH and elevated PCO₂ and bicarbonate
13. Respiratory alkalosis: Elevated PH and decreased PCO₂ and bicarbonate 

Respiratory Acidosis:

1. Caused by excess hydrogen ion in blood when buffer system is insufficient.
2. Hypoventilation is a major cause.
3. Conditions causing respiratory obstruction or airway inflammation can cause respiratory acidosis.
4. Clinical manifestations include hypoventilation, increased urine acid levels, drowsiness, seizures, dysrhythmia, headache, and coma.
5. Nursing interventions include suctioning, administration of oxygen, deep breathing, and coughing. Do not prescribe opioids or respiratory depressants to treat restlessness.

Respiratory Alkalosis:

1. Caused by hyperventilation of the lungs.
2. Conditions causing overstimulation of the respiratory system can cause respiratory alkalosis.
3. Symptoms include neuromuscular symptoms, tachycardia, dysrhythmia, lethargy, confusion, nausea, vomiting, and pain.
4. Nursing interventions include calming the patient, using the rebreathing technique, administering calcium gluconate, teaching relaxation techniques, and prescribing opioids.

Metabolic Acidosis:

1. Occurs when there is increased acid or loss of bicarbonates in the body
2. Causes include kidney disease, diarrhea, and lactic acidosis
3. Symptoms include hyperventilation, fatigue, confusion, and cardiac arrhythmias
4. Nursing interventions include treating the underlying cause, administering bicarbonate, and monitoring electrolyte levels.

Metabolic Alkalosis:

1. Occurs when there is a significant loss of acid or increase in bicarbonates in the body
2. Causes include excessive vomiting or use of diuretics
3. Symptoms include confusion, twitching, and muscle weakness
4. Nursing interventions include treating the underlying cause, administering chloride or ammonium, and monitoring electrolyte levels.

NGN Case Study:
Patient's History: A 65-year-old male patient has been admitted with symptoms of shortness of breath, cough, and wheezing. He has a history' of smoking and asthma.

Nurse's Notes:

1. Observed shortness of breath and wheezing while breathing
2. Chest sounds congested with wheezing and crackles
3. Pulse rate elevated at 120 bpm, Blood pressure is 90/60 mmHg
4. Oxygen saturation is recorded at 88% on room air. 

Physician’s Order:

1. ABG test to evaluate acid-base balance
2. Chest X-ray to evaluate lung condition
3. Spirometry to evaluate lung function
4. Nebulization to relieve wheezing and shortness of breath
5. Bronchodilators to open up airways 

Lab Values- ABG test results:

1. pH: 7.25
2. PaCO₂: 50 mm Hg
3. HCO₃: 20 mEq/L
4. O₂ Sat: 88% 

Question 1.
What condition does the patient have based on the ABG test results?
(a) Respiratory Acidosis
(b) Respiratory Alkalosis
(c) Metabolic Acidosis
(d) Metabolic Alkalosis
Answer: 
(a) Respiratory Acidosis

Explanation: 
The patient's ABG test results show a low PH of 7.25, which indicates acidosis. The elevated PaCO₂ of 50 mm Hg suggests that the acidosis is caused by decreased ventilation. The bicarbonate levels are below the normal range, which shows that the body is compensating for the acidosis. The oxygen saturation is also below normal, supporting the respiratory acidosis diagnosis. The patient's history of smoking and asthma further supports the diagnosis. 

Question 2. 
What is the most likely diagnosis for the 65-year-old male patient based on the given information? SATA
(a) Chronic Obstructive Pulmonary Disease (COPD)
(b) Bronchitis
(c) Pneumonia
(d) Acute Respiratory Distress Syndrome (ARDS)
(e) Asthma exacerbation
Answer: 
(a) Chronic Obstructive Pulmonary Disease (COPD) and (e) Asthma exacerbation are the correct answers.

Explanation: 
(a) Chronic Obstructive Pulmonary Disease (COPD) is a likely diagnosis based on the patient's history of smoking and asthma, symptoms of shortness of breath, wheezing, and cough, chest sounds congested with wheezing and crackles, and elevated pulse rate.

(b) Bronchitis is not a likely diagnosis as the patient's symptoms, such as shortness of breath, elevated pulse rate, and low blood pressure, suggest a more severe condition than just bronchitis.

(c) Pneumonia is not a likely diagnosis as the patient’s chest sounds congested with wheezing and crackles, which is not a typical sign of pneumonia.

(d) Acute Respiratory Distress Syndrome (ARDS) is not a likely diagnosis as the patient's ABG results (PH 7.25 and PaCO₂ 50 mm Hg) do not meet the criteria for ARDS.

(e) Asthma exacerbation is a correct answer as the patient has a history of asthma and is showing symptoms of wheezing and shortness of breath. The physician's order of nebulization and bronchodilators also supports this diagnosis. 

Question 3. 
What is the primary cause of respiratory acidosis?
(a) Hypoventilation
(b) Pneumonia
(c) Brain Trauma
(d) Emphysema
Answer: 
(a) Hypoventilation

Explanation: 
Respiratory acidosis is caused by hypoventilation, which is when the lungs cannot exchange CO₂ with the environment due to airway or ventilation obstruction. This causes the excess CO₂ to combine with water to form carbonic acid, leading to an increase in hydrogen ions in the blood and a drop in the PH level. Other conditions such as pneumonia, brain trauma, and emphysema can also cause respiratory acidosis, but hypoventilation is the primary cause.

Question 4. 
What could be the clinical manifestations of respiratory acidosis?
(a) Seizures, warm and flushed skin, and decreased blood pressure.
(b) Drowsy and dizzy, headache, and coma.
(c) Tetany, numbness, and seizures.
(d) Deep and rapid respiration.
Answer: 
(b) Drowsy and dizzy, headache, and coma.
 
Explanation: 
The clinical manifestations of respiratory acidosis are related to the increase of carbonic acid in the blood, leading to hypoventilation. The compensatory mechanism of the kidneys retaining bicarbonate and excreting excess hydrogen ion can cause the patient to feel drowsy and dizzy, have a headache, and even go into a coma. Seizures, warm and flushed skin, and decreased blood pressure are also symptoms, but not specific to respiratory acidosis. Tetany, numbness, and seizures are the symptoms of respiratory alkalosis. Deep and rapid respiration is the symptom of metabolic acidosis.

Question 5. 
What is the main cause of metabolic alkalosis?
(a) Excessive diarrhea
(b) Diabetic ketoacidosis
(c) Excessive vomiting
(d) Kidney disease
Answer:
The main cause of metabolic alkalosis is (c) Excessive vomiting.

Explanation:
This occurs due to the loss of acid through increased bicarbonate ion concentration in the blood. Other causes include diuretics and citrate toxicity during massive transfusion of whole blood.

Question 6. 
If the condition is caused by excessive vomiting that leads to increase in bicarbonate ion concentration in blood, what is the condition?
(a) Respiratory Alkalosis
(b) Respiratory Acidosis
(c) Metabolic Acidosis
(d) Metabolic Alkalosis
Answer: 
(d) Metabolic Alkalosis 

Explanation: 
Metabolic alkalosis is the condition caused by excessive vomiting that leads to increase in bicarbonate ion concentration in blood. This increase in bicarbonate ion concentration leads to loss of acid in the blood and results in metabolic alkalosis. Other causes of metabolic alkalosis include diuretics and citrate toxicity during massive transfusion of whole blood. 

Acid Base Balance ABG NCLEX Practice Questions

Question 1.
A patient has been diagnosed with respiratory acidosis based on an ABG test. Which of the following is likely to have caused the acidosis?
(a) Damage to the alveoli
(b) Hyperventilation
(c) Normal carbon dioxide levels in the blood
(d) High oxygen saturation in the blood
Answer: 
(a) Damage to the alveoli

Explanation: 
When there is damage to the alveoli it can lead to an excess of carbon dioxide in the body that can react with water to form carbonic acid, causing an acidic environment. 

Option (a) Damage to the alveoli is therefore the most likely cause of the acidosis in this case. Option (b) Hyperventilation would actually cause respiratory alkalosis, and options (c) Normal carbon dioxide levels in the blood and (d) High oxygen saturation in the blood are not relevant causes of respiratory acidosis.

Rationale:
Respiratory acidosis is caused by excess carbon dioxide in the body, which can occur when there is damage to the alveoli, resulting in a decreased ability for carbon dioxide to escape from the body.

Question 2.
Mrs. Deniel has been diagnosed with respiratory acidosis and has an ABG test showing the following results: PH 7.25, PaCO₂ 50 mm Hg, HCO₃ 18 niEq/L, O₂ Sat 95%, and PaO₂ 90 mm Hg. Question 2 What is the most likely cause of her respiratory acidosis? 
(a) Hyperventilation
(b) Damage to the alveoli
(c) Low oxygen in the hemoglobin
(d) Acidic environment in the body
Answer: 
(b) Damage to the alveoli

Explanation: 
The ABG test results indicate that the patient has a PH level of 7.25, which is lower than the normal range of 7.35-7.45. This suggests that the patient is experiencing acidosis. The increase in PaCO₂ and the decrease in HCO₃ (18 mEq/L, which is lower than the normal range of 22-26 mEq/L) are both consistent with respiratory acidosis.

The normal range for PaO₂ is 80-100 mm Hg, and the patient's PaO₂ level of 90 mm Hg is within this range, indicating that their oxygen saturation is normal. Therefore, the most likely cause of the patient's respiratory acidosis is damage to the alveoli, which is preventing them from effectively exhaling carbon dioxide.

Rationale: 
Respiratory acidosis can occur when there is damage to the alveoli, resulting in excess carbon dioxide in the body that reacts with water to form carbonic acid and creates an acidic environment.

Question 3.
A patient with a lung disease has an ABG test performed and the results show a PH of 7.20, PaCO₂ of 60 mm Hg, and HCO₃ of 20 mEq/L.
Question 3 Based on the ABG test results, what is the patient's acid-base balance condition?
(a) Acidosis
(b) Alkalosis
(c) Normal
Answer: 
(a) Acidosis

Explanation:
A pH value lower than 7.35 indicates acidosis and a PaCO₂ value higher than the normal range can also indicate acidosis, particularly in the case of a lung disease where carbon dioxide cannot escape the body properly. The HCO₃ value of 20 mEq/L is lower than the normal range of 22-26 mEq/L, which can also contribute to acidosis. Therefore, based on these ABG test results, the patient's acid-base balance is in an acidosis condition.

Rationale: 
The pH of the patient's blood is 7.20, which is lower than the normal range of 7.35-7.45. The PaCO₂ is also higher than the normal range of 35-45 mm Hg. These values indicate that the patient's acid-base balance is in an acidotic condition.

Question 4.
A patient with a lung disease is experiencing difficulty breathing and has an ABG test done. The results show a PH of 7.2, PaCO₂ of 60 mm Hg, HCO₃ of 20mEq/L, O₂ Sat of 90%, and PaO₂ of 70 mm Hg.
Question 4 Based on the results of the ABG test, what is the patient's acid-base balance condition?
(a) Acidosis
(b) Alkalosis
(c) Normal
(d) Cannot be determined 
Answer: 
(a) Acidosis

Explanation: 
The PH of the blood is a measure of its acidity or basicity. A PH below 7.35 indicates acidosis, while a PH above 7.45 indicates alkalosis. The PaCO₂ is a measure of the amount of carbon dioxide in the blood and how well it can move out of the body. An elevated PaCO₂ can contribute to acidosis.

Rationale:
The results of the ABG test indicate that the patient has acidosis, as the PH is below the normal range of 7.35-7.45 and the PaCO₂ is above the normal range of 35-45 mm Hg. 

Question 5.
A 45-year-old male patient presents with symptoms of shortness of breath, dizziness, and a headache. H is blood pressure is low and he is feeling drowsy. Upon examination, it is determined that the patient has respiratory acidosis due to pneumonia.
What is the main cause of respiratory acidosis?
(a) Hypoventilation
(b) Pneumonia
(c) Bronchitis
(d) Brain Trauma 
Answer: 
(a) Hypoventilation

Explanation:
Respiratory acidosis is a condition in which there is an excess of hydrogen ions in the blood that cannot be absorbed by the buffer system in the blood. This usually occurs when there is alveolar hypoventilation, which is a reduction in the amount of air being exchanged in the lungs. Other causes of respiratory acidosis include airway obstruction or ventilation obstruction, such as pneumonia, bronchitis, asthma, pulmonary edema, COPD, and emphysema.

Rationale: 
The main cause of respiratory acidosis is hypoventilation, which occurs when the lungs do not exchange enough carbon dioxide with the environment. In this case, the patient's symptoms and examination results suggest that the cause of the respiratory acidosis is pneumonia, but pneumonia is not the main cause of the condition.

Question 6.
A patient is brought to the emergency department with symptoms of respiratory acidosis. Upon examination, the patient is found to have a fever and congestion in the lungs. The patient's blood gas analysis shows a PH of 7.25 and a PCO₂ of 60 mm Hg. The patient is experiencing seizures and dizziness. 
Which of the following is a symptom of respiratory acidosis?
(a) Tetany
(b) Numbness
(c) Seizures
(d) Warm and flushed skin 
Answer: 
(d) Warm and flushed skin 

Explanation:
Respiratory acidosis is a condition in which there is an excess of hydrogen ions in the blood, leading to an acidic PH. This can be caused by conditions that obstruct ventilation or airflow, such as pneumonia or bronchitis. In response to respiratory acidosis, the kidneys will compensate by retaining bicarbonate and excreting excess hydrogen ions in the urine.

Symptoms of respiratory acidosis may include hypoventilation, an increase in urine acidity, seizures, warm and flushed skin, decreased blood pressure, dizziness, drowsiness, headache, and coma. It is important to provide oxygen and encourage deep breathing and coughing to help clear the airway in cases of respiratory acidosis, and to avoid prescribing respiratory depressants or opioids, which could worsen the condition.

Rationale:
Respiratory acidosis is caused by alveolar hypoventilation, leading to an excess of carbonic acid in the blood. Symptoms of respiratory acidosis may include warm and flushed skin, as well as seizures and dizziness. Tetany and numbness are symptoms of respiratory alkalosis, which is caused by hyperventilation of the lungs.

Question 7.
A patient brought to the emergency department upon examination is experiencing hyperventilation and is anxious and agitated. The patient's blood gas analysis shows a PH of 7.55 and a PCO₂ of 30 mm Hg. The patient is experiencing tetany, numbness, and seizures.
Which of the following is a cause of respiratory alkalosis?
(a) Pneumonia
(b) Bronchitis
(c) Anxiety 
(d) Pulmonary edema 
Answer: 
(c) Anxiety 

Explanation: 
Respiratory alkalosis is a condition in which there is a decrease in carbonic acid in the blood, leading to an alkaline PH. This can be caused by overstimulation of the respiratory system, which leads to hyperventilation and an excess of carbon dioxide being exhaled. Causes of respiratory alkalosis can include anxiety, panic, fever, pregnancy, certain medications (such as aspirin or salicylates), and certain medical conditions (such as diabetic ketoacidosis or damage to the brain stem).

Symptoms of respiratory alkalosis may include hyperventilation, tetany, numbness, seizures, and confusion. It is important to identify and address the underlying cause of respiratory alkalosis, and to provide oxygen and other supportive care as needed to help regulate the PH of the blood.

Rationale:
Respiratory alkalosis is caused by hyperventilation of the lungs, which can be triggered by various factors such as anxiety, panic, fever, pregnancy, certain medications, and certain medical conditions. Pneumonia, bronchitis, and pulmonary edema, on the other hand, are all causes of respiratory acidosis.

Question 8.
A patient is brought to the emergency department with symptoms of respiratory alkalosis. Upon examination, the patient is experiencing anxiety and hyperventilation. The patient's blood gas analysis shows a PH of 7.55 and a PCO₂ of 35 mm Hg. The patient is experiencing tetany and numbness in the hands and feet.
Which of the following is a cause of respiratory alkalosis?
(a) Pneumonia
(b) Asthma
(c) Anxiety
(d) Pulmonary edema
Answer: 
(c) Anxiety

Explanation: 
Respiratory alkalosis is a condition in which there is a decrease in carbonic acid and an increase in PH due to hyperventilation of the lungs. This can be caused by various factors, including overstimulation of the respiratory system, such as anxiety or panic, as well as hyperthermia, pregnancy, certain drugs, and conditions such as diabetic ketoacidosis or hysteria.

Signs and symptoms of respiratory alkalosis may include tetany, numbness, seizures, and other neuromuscular symptoms, as well as dizziness, headache, and confusion. Nursing interventions for respiratory-alkalosis may include encouraging the patient to slow their breathing and try relaxation techniques, addressing the underlying cause of the alkalosis, and in severe cases, administering oxygen or other interventions to restore normal oxygen levels in the blood.

Rationale:
Respiratory alkalosis is caused by hyperventilation of the lungs, leading to a decrease in carbonic acid and an increase in PH. Causes of respiratory alkalosis may include overstimulation of the respiratory system, such as anxiety or panic, as well as hyperthermia, pregnancy, certain drugs, and conditions such as diabetic ketoacidosis or hysteria. Pneumonia, asthma, and pulmonary edema are causes of respiratory acidosis, not alkalosis.

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