Arterial Blood Gas (ABG) Interpretation Quiz Questions With Answers

The normal value for the pH is 7.40. pH is a measure of the acidity or alkalinity of a solution, with a value of 7 considered neutral. A pH value higher than 7 indicates alkalinity, while a value lower than 7 indicates acidity. Therefore, a pH of 7.40 falls within the normal range, indicating a slightly alkaline solution.

The given values of pH, pCO2, and HCO3- fall within the normal range. A pH of 7.40 indicates a neutral blood pH, which is considered normal. A pCO2 of 40 mmHg and HCO3- level of 24 mEq/L are also within the normal ranges, indicating a balance between respiratory and metabolic processes. Therefore, the overall interpretation is that the values are normal.

Acidemia is a condition characterized by an abnormally low blood pH level. A pH level less than 7.35 indicates acidemia, as it indicates an excess of hydrogen ions in the blood, resulting in increased acidity. The other options, such as a pCO2 greater than 45 or HCO3- more than 26, are not indicators of acidemia but may suggest other acid-base imbalances. A pH level more than 7.45 would indicate alkalemia, which is the opposite of acidemia.

The respiratory parameter of the arterial blood gas set is pCO2 because pCO2 represents the partial pressure of carbon dioxide in the arterial blood. This parameter is important in assessing the respiratory function and acid-base balance of an individual. Changes in pCO2 levels can indicate respiratory disorders such as hypoventilation or hyperventilation.

The given arterial blood gas set shows a pH level of 7.51, which is higher than the normal range of 7.35-7.45, indicating alkalosis. The pCO2 level is within the normal range of 35-45 mmHg, suggesting that the respiratory system is not compensating for the alkalosis. The HCO3- level is elevated at 31 mEq/L, confirming a metabolic component. Therefore, the interpretation of "Uncompensated metabolic alkalosis" is correct.

Respiratory failure occurs when the lungs are unable to effectively exchange oxygen and carbon dioxide. One of the key indicators of respiratory failure is an elevated pCO2 level, which refers to an increased partial pressure of carbon dioxide in the blood. This is because the lungs are not able to remove carbon dioxide efficiently, leading to a buildup in the bloodstream. Therefore, a pCO2 level above 45 is often associated with respiratory failure.

This answer is correct because the pH is below the normal range (7.35-7.45), indicating acidosis. The pCO2 is elevated (normal range 35-45 mmHg), suggesting respiratory acidosis. Additionally, the HCO3- level is also elevated (normal range 22-28 mEq/L), indicating metabolic compensation. Therefore, it is partially compensated respiratory acidosis.

The given values indicate a pH of 7.48, which is higher than the normal range (7.35-7.45). This suggests alkalosis. Additionally, the pCO2 value of 30 is lower than the normal range (35-45), indicating respiratory alkalosis. However, the HCO3- value of 23 is within the normal range (22-28), suggesting that the kidneys have not fully compensated for the respiratory alkalosis. Therefore, the correct answer is "Partially compensated respiratory alkalosis."

The given values of pH, pCO2, and HCO3- indicate a metabolic alkalosis. The pH is higher than the normal range (7.35-7.45) and the HCO3- level is elevated (normal range: 22-26 mEq/L). The pCO2 value is also increased, indicating compensation by the respiratory system. However, since the pH is still outside the normal range, it suggests that the compensation is not fully effective, resulting in a partially compensated metabolic alkalosis.

To determine the correct diagnosis from the given blood gas values (pH 7.33, pCO2 29, HCO3- 16), we need to analyze the values and understand the relationship between them:

Normal pH range: 7.35-7.45

Normal pCO2 range: 35-45 mmHg

Normal HCO3- range: 22-26 mEq/L

Analysis:

pH: The pH is 7.33, which is slightly below the normal range, indicating acidemia (a tendency towards acidosis).

pCO2: The pCO2 is 29 mmHg, which is below the normal range, indicating a potential respiratory alkalosis (since pCO2 is lower, indicating less CO2, which is an acid).

HCO3-: The HCO3- is 16 mEq/L, which is below the normal range, indicating a metabolic acidosis (since bicarbonate is lower, indicating less base).

Interpretation:

The low pH suggests acidemia.

The low pCO2 suggests a respiratory compensation for acidosis.

The low HCO3- confirms a primary metabolic acidosis.

Because the pCO2 is low, it indicates that the respiratory system is trying to compensate for the metabolic acidosis by blowing off CO2 to raise the pH. The pH is close to normal but still on the acidic side, suggesting partial compensation.

 

In a long-standing metabolic acidosis, an increase in respiratory rate is indeed an example of compensation. It is the body's way of attempting to correct the acid-base imbalance by blowing off carbon dioxide (a respiratory acid) to raise the pH.