Mr. Casper, a 55-year-old patient with Gastroesophageal Reflux Disease (GERD), consumes about 16 Tums antacid tablets daily. An Arterial Blood Gas (ABG) test is conducted to evaluate his acid/base balance. The results are as follows: pH 7.46, CO2 46, PO2 86, HCO3 29, SaO2 97%. What is the interpretation of these results?
Uncompensated Respiratory Acidosis
Compensated Metabolic Acidosis
Partially Compensated Metabolic Alkalosis
Partially Compensated Respiratory Acidosis
The Correct Answer is C
Choice A rationale:
Uncompensated Respiratory Acidosis is characterized by a low pH (less than 7.35) and a high pCO2 (greater than 45 mmHg). In this case, the pH is slightly elevated (7.46), making this option less likely.
While the pCO2 is elevated (46 mmHg), the body has begun to compensate, as evidenced by the elevated HCO3 (29 mEq/L). This partial compensation does not align with an uncompensated respiratory acidosis.
Choice B rationale:
Compensated Metabolic Acidosis would present with a normal pH (7.35-7.45) due to full compensation by the respiratory system. In this case, the pH is slightly elevated (7.46), which is not consistent with full compensation.
Additionally, the HCO3 is elevated (29 mEq/L), which is characteristic of metabolic alkalosis, not acidosis.
Choice C rationale:
Partially Compensated Metabolic Alkalosis is the most likely interpretation based on the ABG results. The pH is elevated (7.46), indicating alkalosis.
The HCO3 is also elevated (29 mEq/L), which is the primary cause of metabolic alkalosis.
The pCO2 is elevated (46 mmHg), which is a compensatory mechanism to try to normalize the pH. However, the compensation is not complete, as the pH is still slightly elevated.
This partial compensation is consistent with partially compensated metabolic alkalosis.
Choice D rationale:
Partially Compensated Respiratory Acidosis would present with a low pH (less than 7.35) and an elevated pCO2 (greater than 45 mmHg).
The HCO3 would also be elevated, but to a lesser degree than in metabolic alkalosis, as it's a secondary compensatory mechanism.
In this case, the pH is slightly elevated (7.46), making respiratory acidosis less likely.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A rationale:
This statement is accurate. Early Lyme disease (Stage I) is typically treated with oral antibiotics for 14 to 21 days. This is often effective in clearing the infection and preventing further complications.
Choice B rationale:
This statement is also accurate. A red rash that may resemble a bull's eye is a common early symptom of Lyme disease. It often appears at the site of the tick bite, typically within 3 to 30 days after the bite.
Choice C rationale:
This statement is incorrect. While Lyme disease can be serious if not treated, it is rarely fatal. Most people who are treated for Lyme disease recover fully. However, if left untreated, it can lead to chronic health problems, such as arthritis, neurological problems, and heart issues.
Choice D rationale:
This statement is accurate. Taking precautions against tick bites is essential for preventing Lyme disease. Ticks are most active during the warmer months, so it's crucial to be vigilant about tick prevention during the spring, summer, and fall.
Correct Answer is A
Explanation
Choice A rationale:
Hyperventilation is a condition characterized by rapid and deep breathing, leading to excessive removal of carbon dioxide (CO2) from the body. This decrease in CO2 levels actually causes respiratory alkalosis, not respiratory acidosis.
CO2 is a weak acid, and its removal from the blood raises the blood pH, making it more alkaline. Key mechanisms involved in hyperventilation-induced respiratory alkalosis:
Increased alveolar ventilation: Hyperventilation increases the rate at which CO2 is expelled from the lungs, reducing its concentration in the blood.
Shift in the equilibrium of the carbonic acid-bicarbonate buffer system: The reduction in CO2 levels drives the equilibrium towards the formation of bicarbonate ions, further reducing the concentration of hydrogen ions and increasing pH.
Renal compensation: The kidneys respond to respiratory alkalosis by excreting more bicarbonate ions, which helps to normalize the blood pH.
Choice B rationale:
Asthma is a chronic respiratory disease characterized by inflammation and narrowing of the airways. This can lead to impaired ventilation and retention of CO2, which can contribute to respiratory acidosis.
Mechanisms by which asthma can cause respiratory acidosis:
Bronchoconstriction: Narrowed airways impede airflow, making it difficult to expel CO2 from the lungs.
Air trapping: Inflammation and mucus production can lead to air becoming trapped in the lungs, further increasing CO2 levels.
Hypoventilation: Severe asthma attacks can cause respiratory muscle fatigue, leading to a decrease in breathing rate and inadequate CO2 removal.
Choice C rationale:
Chronic obstructive pulmonary disease (COPD) is a group of lung diseases characterized by chronic obstruction of airflow. This obstruction can lead to impaired ventilation and retention of CO2, which can contribute to respiratory acidosis.
Mechanisms by which COPD can cause respiratory acidosis:
Emphysema: Destruction of lung tissue reduces the surface area available for gas exchange, making it difficult to expel CO2. Chronic bronchitis: Inflammation and mucus production in the airways can obstruct airflow and trap CO2 in the lungs.
Hypoventilation: COPD can lead to respiratory muscle fatigue and a decrease in breathing rate, further impairing CO2 removal.
Choice D rationale:
Pulmonary embolism (PE) is a blockage of an artery in the lungs, usually by a blood clot. This can lead to impaired gas exchange and a decrease in oxygen levels in the blood. In severe cases, PE can also cause respiratory acidosis due to inadequate CO2 removal.
Mechanisms by which PE can cause respiratory acidosis:
Ventilation-perfusion mismatch: PE obstructs blood flow to a portion of the lungs, reducing the amount of CO2 that can be removed from those areas.
Hypoxemia: Low oxygen levels in the blood can stimulate the respiratory drive, leading to hyperventilation and CO2 retention.
Right heart failure: PE can strain the right side of the heart, leading to decreased pulmonary blood flow and impaired CO2 removal.
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