Arterial Blood Gas (ABG) Analysis NCLEX Exam #4 (10 Questions)

1. An elderly client gets admitted to the hospital, and he is in a coma. Analysis of the arterial blood provided the following values: PCO2 16 mm Hg, HCO3- 5 mmol/L, and pH 7.1. As a good nurse, you know what the normal value is for HCO3 is:

20 mmol/L

24 mmol/L

29 mmol/L

31 mmol/L

The normal value for HCO3- (bicarbonate) in arterial blood is 24 mmol/L. In this case, the client's HCO3- level is significantly lower at 5 mmol/L, indicating a condition called metabolic acidosis. This is further supported by the low pH value of 7.1, which is below the normal range of 7.35-7.45. Metabolic acidosis can occur due to various reasons such as kidney dysfunction, diabetic ketoacidosis, or ingestion of certain toxins. It is important for the nurse to recognize this abnormality and inform the healthcare team for appropriate intervention and treatment.

Explanation

The normal value for HCO3- (bicarbonate) in arterial blood is 24 mmol/L. In this case, the client's HCO3- level is significantly lower at 5 mmol/L, indicating a condition called metabolic acidosis. This is further supported by the low pH value of 7.1, which is below the normal range of 7.35-7.45. Metabolic acidosis can occur due to various reasons such as kidney dysfunction, diabetic ketoacidosis, or ingestion of certain toxins. It is important for the nurse to recognize this abnormality and inform the healthcare team for appropriate intervention and treatment.

2. An old beggar gets admitted to the emergency department for shortness of breath, fever, and a productive cough. After examination, crackles and wheezes are found in the lower lobes; he appears to be tachycardic and shows a bounding pulse. Measurement of arterial blood gas shows pH 7.2, PaCO2 66 mm Hg, HCO3 27 mmol/L, and PaO2 65 mm Hg. As a knowledgeable nurse, you know what the normal value is for pH:

7.20

7.30

7.40

7.50

The normal value for pH in arterial blood is 7.40. A pH of 7.40 indicates a balanced acid-base status in the body. In this case, the pH of 7.2 suggests acidosis, which can be caused by respiratory or metabolic imbalances.

Explanation

The normal value for pH in arterial blood is 7.40. A pH of 7.40 indicates a balanced acid-base status in the body. In this case, the pH of 7.2 suggests acidosis, which can be caused by respiratory or metabolic imbalances.

3. A patient who is hospitalized due to vomiting and a decreased level of consciousness displays slow and deep (Kussmaul breathing), and he is lethargic and irritable in response to stimulation. The doctor diagnosed him of having dehydration. Measurement of arterial blood gas shows pH 7.0, PaO2 90 mm Hg, PaCO2 22 mm Hg, and HCO3 14 mmol/L; other results are Na+ 120 mmol/L, K+ 2.5 mmol/L, and Cl- 95 mmol/L. As a knowledgeable nurse, you know that the normal value for PaCO2 is:

22 mm Hg

36 mm Hg

48 mm Hg

50 mm Hg

The correct answer is 36 mm Hg. The given arterial blood gas measurements indicate a condition known as metabolic acidosis. In metabolic acidosis, there is a decrease in the concentration of bicarbonate (HCO3-) in the blood, leading to a decrease in the pH. In order to compensate for this acidosis, the respiratory system increases the rate and depth of breathing, resulting in a decrease in the partial pressure of carbon dioxide (PaCO2) in the blood. The normal value for PaCO2 is around 35-45 mm Hg, so a value of 36 mm Hg falls within the normal range.

Explanation

The correct answer is 36 mm Hg. The given arterial blood gas measurements indicate a condition known as metabolic acidosis. In metabolic acidosis, there is a decrease in the concentration of bicarbonate (HCO3-) in the blood, leading to a decrease in the pH. In order to compensate for this acidosis, the respiratory system increases the rate and depth of breathing, resulting in a decrease in the partial pressure of carbon dioxide (PaCO2) in the blood. The normal value for PaCO2 is around 35-45 mm Hg, so a value of 36 mm Hg falls within the normal range.

4. In a patient undergoing surgery, it was vital to aspirate the contents of the upper gastrointestinal tract. After the operation, the following values were acquired from an arterial blood sample: pH 7.55, PCO2 52 mm Hg, and HCO3- 40 mmol/l. What is the underlying disorder?

Respiratory Acidosis

Respiratory Alkalosis

Metabolic Acidosis

Metabolic Alkalosis

The given arterial blood sample values indicate a high pH (alkalosis) and high HCO3- levels, suggesting a metabolic alkalosis. Metabolic alkalosis occurs when there is an excess of bicarbonate ions in the blood, often caused by conditions such as vomiting, excessive intake of antacids, or certain kidney disorders. Aspiration of the upper gastrointestinal tract can lead to loss of stomach acid, resulting in an imbalance of bicarbonate levels and metabolic alkalosis.

Explanation

The given arterial blood sample values indicate a high pH (alkalosis) and high HCO3- levels, suggesting a metabolic alkalosis. Metabolic alkalosis occurs when there is an excess of bicarbonate ions in the blood, often caused by conditions such as vomiting, excessive intake of antacids, or certain kidney disorders. Aspiration of the upper gastrointestinal tract can lead to loss of stomach acid, resulting in an imbalance of bicarbonate levels and metabolic alkalosis.

5. A mother is admitted in the emergency department following complaints of fever and chills. The nurse on duty took her vital signs and noted the following: Temp = 100 °F; apical pulse = 95; respiration = 20, and deep. Measurement of arterial blood gas shows pH 7.37, PaO2 90 mm Hg, PaCO2 40 mm Hg and HCO3 24 mmol/L. What is your assessment?

Hyperthermia

Hyperthermia and Respiratory Alkalosis

Hypothermia

Hypothermia and Respiratory Alkalosis

The given vital signs and arterial blood gas measurements indicate that the mother has a fever (elevated temperature) and normal respiratory values. The pH, PaO2, PaCO2, and HCO3 levels are within the normal range, suggesting that there is no respiratory alkalosis or acidosis present. Therefore, the assessment is Hyperthermia, which is consistent with the symptoms of fever and chills mentioned in the question.

Explanation

The given vital signs and arterial blood gas measurements indicate that the mother has a fever (elevated temperature) and normal respiratory values. The pH, PaO2, PaCO2, and HCO3 levels are within the normal range, suggesting that there is no respiratory alkalosis or acidosis present. Therefore, the assessment is Hyperthermia, which is consistent with the symptoms of fever and chills mentioned in the question.

6. Stephen, a 6-year-old boy, was brought to the hospital with her mother’s complaint that her son is vomiting, nauseated, and showed overall weakness. After some tests, the nurse finds the laboratory results: potassium: 2.9 mEq. the boy is at risk for which primary acid-base imbalance if medical intervention is not carried out?

Respiratory Acidosis

Respiratory Alkalosis

Metabolic Acidosis

Metabolic Alkalosis

The laboratory result shows a low level of potassium (hypokalemia), which is commonly associated with metabolic alkalosis. Metabolic alkalosis occurs when there is an excess of bicarbonate (HCO3-) in the body, leading to an increase in pH. This can be caused by factors such as vomiting, which leads to loss of acid (hydrochloric acid) from the stomach, resulting in an imbalance in the body's acid-base levels. If medical intervention is not carried out to address the underlying cause and restore electrolyte balance, the boy is at risk of developing metabolic alkalosis.

Explanation

The laboratory result shows a low level of potassium (hypokalemia), which is commonly associated with metabolic alkalosis. Metabolic alkalosis occurs when there is an excess of bicarbonate (HCO3-) in the body, leading to an increase in pH. This can be caused by factors such as vomiting, which leads to loss of acid (hydrochloric acid) from the stomach, resulting in an imbalance in the body's acid-base levels. If medical intervention is not carried out to address the underlying cause and restore electrolyte balance, the boy is at risk of developing metabolic alkalosis.

7. A company driver is found at the scene of an automobile accident in a state of emotional distress. He tells the paramedics that he feels dizzy, tingling in his fingertips, and does not remember what happened to his car. Respiratory rate is rapid at 34/minute. Which primary acid-base disturbance is the young man at risk for if medical attention is not provided?

Respiratory Acidosis

Respiratory Alkalosis

Metabolic Acidosis

Metabolic Alkalosis

The driver is experiencing symptoms of hyperventilation, such as dizziness, tingling in the fingertips, and rapid respiratory rate. These symptoms are indicative of respiratory alkalosis, which is caused by excessive elimination of carbon dioxide through hyperventilation. Without medical attention, the driver's condition may worsen, leading to further imbalances in the acid-base levels in the body.

Explanation

The driver is experiencing symptoms of hyperventilation, such as dizziness, tingling in the fingertips, and rapid respiratory rate. These symptoms are indicative of respiratory alkalosis, which is caused by excessive elimination of carbon dioxide through hyperventilation. Without medical attention, the driver's condition may worsen, leading to further imbalances in the acid-base levels in the body.

8. A young woman is found comatose, having taken an unknown number of sleeping pills an unknown time before. An arterial blood sample yields the following values: pH 6.90, HCO3- 13 meq/liter, and PaCO2 68 mmHg. This patient’s acid-base status is most accurately described as:

Metabolic Acidosis

Respiratory Acidosis

Simultaneous Respiratory and Metabolic Acidosis

Respiratory Acidosis with Complete Renal Compensation

The arterial blood sample results indicate a low pH (6.90), which suggests acidosis. The low HCO3- (13 meq/liter) indicates a metabolic acidosis, as it is below the normal range of 22-28 meq/liter. The elevated PaCO2 (68 mmHg) suggests respiratory acidosis, as it is above the normal range of 35-45 mmHg. Therefore, the patient's acid-base status is most accurately described as simultaneous respiratory and metabolic acidosis, as both respiratory and metabolic factors are contributing to the acidosis.

Explanation

The arterial blood sample results indicate a low pH (6.90), which suggests acidosis. The low HCO3- (13 meq/liter) indicates a metabolic acidosis, as it is below the normal range of 22-28 meq/liter. The elevated PaCO2 (68 mmHg) suggests respiratory acidosis, as it is above the normal range of 35-45 mmHg. Therefore, the patient's acid-base status is most accurately described as simultaneous respiratory and metabolic acidosis, as both respiratory and metabolic factors are contributing to the acidosis.

9. A mountaineer attempts an assault on a high mountain in the Andes and reaches an altitude of 5000 meters (16,400 ft) above sea level. What will happen to his arterial PCO2 and pH?

Both will be lower than normal.

The pH will rise, and PCO2 will fall.

Both will be higher than normal due to physical exertion.

The pH will fall, and PCO2 will rise

At higher altitudes, the partial pressure of oxygen decreases, causing a condition known as hypoxia. In response, the body compensates by increasing the respiratory rate, leading to a decrease in arterial PCO2 (partial pressure of carbon dioxide) as more CO2 is exhaled. This decrease in PCO2 causes a rise in pH (alkalosis) due to the shift towards a more basic environment. Therefore, the answer "The pH will rise, and PCO2 will fall" is correct.

Explanation

At higher altitudes, the partial pressure of oxygen decreases, causing a condition known as hypoxia. In response, the body compensates by increasing the respiratory rate, leading to a decrease in arterial PCO2 (partial pressure of carbon dioxide) as more CO2 is exhaled. This decrease in PCO2 causes a rise in pH (alkalosis) due to the shift towards a more basic environment. Therefore, the answer "The pH will rise, and PCO2 will fall" is correct.

10. Liza’s mother is seen in the emergency department at a community hospital. She admits that her mother has been taking many tablets of aspirin (salicylates) over the last 24-hour period because of a severe headache. Also, the mother complains of an inability to urinate. The nurse on duty took her vital signs and noted the following: Temp = 97.8 °F; apical pulse = 95; respiration = 32 and deep. Which primary acid-base imbalance is the gentleman at risk for if medical attention is not provided?

Respiratory Acidosis

Respiratory Alkalosis

Metabolic Acidosis

Metabolic Alkalosis

The correct answer is Metabolic Acidosis. Taking excessive amounts of aspirin can lead to salicylate toxicity, which can cause metabolic acidosis. Metabolic acidosis occurs when there is an excess of acid in the body or a loss of bicarbonate, leading to a decrease in pH. The inability to urinate may be a sign of kidney dysfunction, which can contribute to the development of metabolic acidosis. The vital signs, including a normal temperature and pulse rate, do not indicate a respiratory acidosis or alkalosis.

Explanation

The correct answer is Metabolic Acidosis. Taking excessive amounts of aspirin can lead to salicylate toxicity, which can cause metabolic acidosis. Metabolic acidosis occurs when there is an excess of acid in the body or a loss of bicarbonate, leading to a decrease in pH. The inability to urinate may be a sign of kidney dysfunction, which can contribute to the development of metabolic acidosis. The vital signs, including a normal temperature and pulse rate, do not indicate a respiratory acidosis or alkalosis.