ABG Analysis NCLEX Exam

concentration of oxygen and carbon dioxide in the blood




ABG Analysis NCLEX Exam

ABG Analysis

What is Arterial Blood Gas (ABG).

The concentration of oxygen and carbon dioxide in the blood whose partial pressure
are measured along with others factors such as blood pH in order to assess oxygen
saturation and other metabolic indicators in patients especially those with respiratory disorders.

1. George Kent is a 54 year old widower with a history of chronic obstructive pulmonary disease and was rushed to the emergency department with increasing shortness of breath, pyrexia, and a productive cough with yellow-green sputum. He has difficulty in communicating because of his inability to complete a sentence. One of his sons, Jacob, says he has been unwell for three days. Upon examination, crackles and wheezes can be heard in the lower lobes; he has a tachycardia and a bounding pulse. Measurement of arterial blood gas shows pH 7.3, PaCO2 68 mm Hg, HCO3 28 mmol/L, and PaO2 60 mm Hg. How would you interpret this?.

A. Respiratory Acidosis, Uncompensated

B. Metabolic Alkalosis, Uncompensated

C. Respiratory Acidosis, Partially Compensated

D. Metabolic Acidosis, Partially, Compensated

Correct Answer C. The patient has respiratory acidosis (raised carbon dioxide) resulting from an acute exacerbation of chronic obstructive pulmonary disease, with partial compensation.

2. Carl, an elementary student, was rushed to the hospital due to vomiting and a decreased level of consciousness. The patient displays slow and deep (Kussmaul breathing), and he is lethargic and irritable in response to stimulation. He appears to be dehydrated—his eyes are sunken and mucous membranes are dry—and he has a two week history of polydipsia, polyuria, and weight loss. Measurement of arterial blood gas shows pH 7.0, PaO2 90 mm Hg, PaCO2 23 mm Hg, and HCO3 12 mmol/L; other results are Na+ 126 mmol/L, K+ 5 mmol/L, and Cl- 95 mmol/L. What is your assessment?

A. Metabolic Acidosis, Partially Compensated

B. Respiratory Acidosis, Uncompensated

C. Respiratory Acidosis, Partially Compensated

D. Metabolic Alkalosis, Uncompensated

Correct Answer A. The student was diagnosed having diabetes mellitus. The results show that he has metabolic acidosis (low HCO3 -) with respiratory compensation (low CO2).

3. A cigarette vendor was brought to the emergency department of a hospital after she fell into the ground and hurt her left leg. She is noted to be tachycardic and tachypneic. Painkillers were carried out to lessen her pain. Suddenly, she started complaining that she is still in pain and now experiencing muscle cramps, tingling, and paraesthesia. Measurement of arterial blood gas reveals pH 7.6, PaO2 120 mm Hg, PaCO2 31 mm Hg, and HCO3 25 mmol/L. What does this mean?

A. Respiratory Acidosis, Partially Compensated

B. Respiratory Alkalosis, Uncompensated

C. Metabolic Alkalosis, Uncompensated

D. Metabolic Alkalosis, Partially Compensated

Correct Answer B. The primary disorder is acute respiratory alkalosis (low CO2) due to the pain and anxiety causing her to hyperventilate. There has not been time for metabolic compensation.

4. Ricky’s grandmother is suffering from persistent vomiting for two days now. She appears to be lethargic and weak and has myalgia. She is noted to have dry mucus membranes and her capillary refill takes >4 seconds. She is diagnosed as having gastroenteritis and dehydration. Measurement of arterial blood gas shows pH 7.5, PaO2 85 mm Hg, PaCO2 40 mm Hg, and HCO3 34 mmol/L. What acid-base disorder is shown?

A. Respiratory Alkalosis, Uncompensated

B. Respiratory Acidosis, Partially Compensated

C. Metabolic Alkalosis, Partially Compensated

D. Metabolic Alkalosis, Uncompensated

Correct Answer D. The primary disorder is uncompensated metabolic alkalosis (high HCO3 -). As CO2 is the strongest driver of respiration, it generally will not allow hypoventilation as compensation for metabolic alkalosis.

5. Mrs. Johansson, who had undergone surgery in the post-anesthesia care unit (PACU), is difficult to arouse two hours following surgery. Nurse Florence in the PACU has been administering Morphine Sulfate intravenously to the client for complaints of post-surgical pain. The client’s respiratory rate is 7 per minute and demonstrates shallow breathing. The patient does not respond to any stimuli! The nurse assesses the ABCs (remember Airway, Breathing, Circulation!) and obtains ABGs STAT! Measurement of arterial blood gas shows pH 7.10, PaCO2 70 mm Hg and HCO3 24 mEq/L. What does this mean?

A. Respiratory Acidosis, Uncompensated

B. Respiratory Alkalosis, Partially Compensated

C. Metabolic Alkalosis, Partially Compensated

D. Metabolic Acidosis, Uncompensated

6. Baby Angela was rushed to the Emergency Room following her mother’s complaint that the infant has been irritable, difficult to breastfeed and has had diarrhea for the past 3 days. The infant’s respiratory rate is elevated and the fontanels are sunken. The Emergency Room physician orders ABGs after assessing the ABCs. The results from the ABG results show pH 7.39, PaCO2 27 mmHg and HCO3 19 mEq/L. What does this mean?

A. Respiratory Alkalosis, Fully Compensated

B. Metabolic Acidosis, Uncompensated

C. Respiratory Acidosis, Uncompensated

D. Metabolic Acidosis, Fully Compensated

Correct Answer D. Baby Angela has metabolic acidosis due to decreased HCO3 and slightly acidic pH. Her pH value is within the normal range which made the result fully compensated.

7. Mr. Wales, who underwent post-abdominal surgery, has a nasogastric tube. The nurse on duty notes that the nasogastric tube (NGT) is draining a large amount (900 cc in 2 hours) of coffee ground secretions. The client is not oriented to person, place, or time. The nurse contacts the attending physician and STAT ABGs are ordered. The results from the ABGs show pH 7.57, PaCO2 37 mmHg and HCO3 30 mEq/L. What is your assessment?

A. Metabolic Acidosis, Uncompensated

B. Respiratory Alkalosis, Uncompensated

C. Metabolic Alkalosis, Partially Compensated

D. Metabolic Alkalosis, Uncompensated

Correct Answer D. The postoperative client’s ABG results show that he has metabolic alkalosis because of an increased pH and HCO3. It is uncompensated due to the normal PaCO2 which is within 35 to 45 mmHg.

8. Client Z is admitted to the hospital and is to undergo brain surgery. The client is very anxious and scared of the upcoming surgery. He begins to hyperventilate and becomes very dizzy. The client loses consciousness and the STAT ABGs reveal pH 7.61, PaCO2 22 mmHg and HCO3 25 mEq/L. What is the ABG interpretation based on the findings?

A. Respiratory Alkalosis, Uncompensated

B. Metabolic Acidosis, Uncompensated

C. Respiratory Alkalosis, Partially Compensated

D. Metabolic Alkalosis, Partially Compensated

Correct Answer A. The results show that client Z has respiratory alkalosis since there is an increase in the pH value and a decrease in PaCO2 which are both basic. It is uncompensated due to the normal HCO3 which is within 22-26 mEq/L.

9. Three-year-old Adrian is admitted to the hospital with a diagnosis of asthma and respiratory distress syndrome. The mother of the child reports to the nurse on duty that she has witnessed slight tremors and behavioral changes in her child over the past four days. The attending physician orders routine ABGs following an assessment of the ABCs. The ABG results are pH 7.35, PaCO2 72 mmHg and HCO3 38 mEq/L. What acid-base disorder is shown?

A. Respiratory Acidosis, Uncompensated

B. Respiratory Alkalosis, Fully Compensated

C. Metabolic Alkalosis, Partially Compensated

D. Respiratory Acidosis, Fully Compensated

Correct Answer D. The patient has respiratory acidosis (raised carbon dioxide) resulting from asthma and respiratory distress syndrome, with compensation having normal pH value within 7.35to 7.45, increased PaCO2 which is acidic and increased HCO3 which is basic.

A. Metabolic Acidosis

B. Metabolic Alkalosis

C. Respiratory Alkalosis

D. Respiratory Acidosis

Correct Answer D. One of the risk factors of having respiratory acidosis is hypoventilation which may be due to brain trauma, coma, and hypothyroidism or myxedema. Other risk factors include COPD, Respiratory conditions such as pneumothorax, pneumonia and status asthmaticus. Drugs such as Morphine and MgSO4 toxicity are also risk factors of respiratory acidosis.


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