ABG Study Questions And Answers Graded A
A patient who has required prolonged mechanical ventilation has the following arterial blood gas
results: pH 7.48, PaO2 85 mm Hg, PaCO2 32 mm Hg, and HCO3 25 mEq/L. The nurse
interprets these results as
a. metabolic acidosis.
b. metabolic alkalosis.
c. respiratory acidosis.
d. respiratory alkalosis. Correct Answer: ANS: D
The pH indicates that the patient has alkalosis and the low PaCO2 indicates a respiratory cause.
The other responses are incorrect based on the pH and the normal HCO3.
A patient has the following arterial blood gas (ABG) results: pH 7.32, PaO2 88 mm Hg, PaCO2
37 mm Hg, and HCO3 16 mEq/L. The nurse interprets these results as
a. metabolic acidosis.
b. metabolic alkalosis.
c. respiratory acidosis.
d. respiratory alkalosis. Correct Answer: ANS: A
The pH and HCO3 indicate that the patient has a metabolic acidosis. The ABGs are inconsistent
with the other responses.
A 2-year-old child was brought into the emergency department after ingesting several morphine
tablets
from a bottle in his mother's purse. The nurse knows that the child is at greatest risk for which
acid-base imbalance?
a) Respiratory acidosis
b) Respiratory alkalosis
c) Metabolic acidosis
d) Metabolic alkalosis Correct Answer: ANS: A
Morphine overdose can cause respiratory depression and hypoventilation. Hypoventilation
results in retention of CO2 and respiratory acidosis. Respiratory alkalosis would result from
hyperventilation, causing a decrease in CO2 levels. Metabolic acid-base imbalance would be a
result of kidney dysfunction, vomiting, diarrhea, or other conditions that affect metabolic acids.
A patient was admitted for a bowel obstruction and has had a nasogastric tube set to low
intermittent
suction for the past 3 days. The patient's respiratory rate has decreased to 12 breaths per minute.
The nurse would expect the patient to have which of the following arterial blood gas values?
a) pH 7.78, PaCO2 40 mm Hg, HCO3- 30 mEq/L
b) pH 7.52, PaCO2 48 mm Hg, HCO3- 28 mEq/L
c) pH 7.35, PaCO2 35 mm Hg, HCO3- 26 mEq/L
d) pH 7.25, PaCO2 47 mm Hg, HCO3- 29 mEq/L Correct Answer: ANS: B
Compensated metabolic alkalosis should show alkalosis pH and HCO3- (metabolic) values, with
a slightly acidic CO2 (compensatory respiratory acidosis). In this case, pH 7.52 is alkaline
, (normal = 7.35 to 7.45), PaCO2is acidic (normal 35 to 45 mm Hg), and HCO3- is elevated
(normal = 22 to 26 mEq/L). A result of pH 7.78, PaCO2 40 mm Hg, HCO3- 30 mEq/L is
uncompensated metabolic alkalosis. pH 7.35, PaCO2 35 mm Hg, HCO3- 26 mEq/L is within
normal limits. pH 7.25, PaCO2 47 mm Hg, HCO3- 29 mEq/L is compensated respiratory
acidosis.
The nurse would not expect full compensation to occur for which acid-base imbalance?
a) Respiratory acidosis
b) Respiratory alkalosis
c) Metabolic acidosis
d) Metabolic alkalosis Correct Answer: ANS: B
Usually the cause of respiratory alkalosis is a temporary event (e.g., an asthma or anxiety attack).
The kidneys take about 24 hours to compensate for an event, so it is unlikely to see much if any
compensation for respiratory alkalosis. Respiratory acidosis usually results from longer-term
conditions such as chronic lung disease, narcotic overdose, or another event that causes
respiratory depression. The kidneys still do not respond for about 24 hours, but usually the event
is still occurring. For both metabolic imbalances, the respiratory system is quick to attempt to
compensate: however, it may have difficulty sustaining that compensation.
Which laboratory value should the nurse examine when evaluating uncompensated respiratory
alkalosis?
a) PaO2
b) Anion gap
c) PaCO2
d) HCO3- Correct Answer: ANS: C
Uncompensated respiratory imbalances are seen in the PaCO2 levels. PaO2 indicates oxygen
status. Anion gap is used for metabolic acidosis. HCO3- is used to evaluate compensation for
respiratory imbalances or uncompensated metabolic imbalances.
The nurse is caring for a diabetic patient in renal failure. Which laboratory findings would the
nurse expect?
a) pH 7.3, PaCO2 36 mm Hg, HCO3- 19 mEq/L
b) pH 7.5, PaCO2 35 mm Hg, HCO3- 35 mEq/L
c) pH 7.3, PaCO2 47 mm Hg, HCO3- 23 mEq/L
d) pH 7.35, PaCO2 40 mm Hg, HCO3- 25 mEq/L Correct Answer: ANS: A
Patients in renal failure develop metabolic acidosis. The laboratory values that reflect this are pH
7.3, PaCO2 36 mm Hg, HCO3- 19 mEq/L. A laboratory finding of pH 7.5, PaCO2 35 mm Hg,
HCO3- 35 mEq/L is metabolic alkalosis. pH 7.3, PaCO2 47 mm Hg, HCO3- 23 mEq/L is
respiratory acidosis. pH 7.35, PaCO2 40 mm Hg, HCO3- 25 mEq/L values are within normal
range.
A patient with a lower respiratory infection has pH of 7.25, PaCO2 of 55 mm Hg, and HCO3- of
20 mEq/L.
A patient who has required prolonged mechanical ventilation has the following arterial blood gas
results: pH 7.48, PaO2 85 mm Hg, PaCO2 32 mm Hg, and HCO3 25 mEq/L. The nurse
interprets these results as
a. metabolic acidosis.
b. metabolic alkalosis.
c. respiratory acidosis.
d. respiratory alkalosis. Correct Answer: ANS: D
The pH indicates that the patient has alkalosis and the low PaCO2 indicates a respiratory cause.
The other responses are incorrect based on the pH and the normal HCO3.
A patient has the following arterial blood gas (ABG) results: pH 7.32, PaO2 88 mm Hg, PaCO2
37 mm Hg, and HCO3 16 mEq/L. The nurse interprets these results as
a. metabolic acidosis.
b. metabolic alkalosis.
c. respiratory acidosis.
d. respiratory alkalosis. Correct Answer: ANS: A
The pH and HCO3 indicate that the patient has a metabolic acidosis. The ABGs are inconsistent
with the other responses.
A 2-year-old child was brought into the emergency department after ingesting several morphine
tablets
from a bottle in his mother's purse. The nurse knows that the child is at greatest risk for which
acid-base imbalance?
a) Respiratory acidosis
b) Respiratory alkalosis
c) Metabolic acidosis
d) Metabolic alkalosis Correct Answer: ANS: A
Morphine overdose can cause respiratory depression and hypoventilation. Hypoventilation
results in retention of CO2 and respiratory acidosis. Respiratory alkalosis would result from
hyperventilation, causing a decrease in CO2 levels. Metabolic acid-base imbalance would be a
result of kidney dysfunction, vomiting, diarrhea, or other conditions that affect metabolic acids.
A patient was admitted for a bowel obstruction and has had a nasogastric tube set to low
intermittent
suction for the past 3 days. The patient's respiratory rate has decreased to 12 breaths per minute.
The nurse would expect the patient to have which of the following arterial blood gas values?
a) pH 7.78, PaCO2 40 mm Hg, HCO3- 30 mEq/L
b) pH 7.52, PaCO2 48 mm Hg, HCO3- 28 mEq/L
c) pH 7.35, PaCO2 35 mm Hg, HCO3- 26 mEq/L
d) pH 7.25, PaCO2 47 mm Hg, HCO3- 29 mEq/L Correct Answer: ANS: B
Compensated metabolic alkalosis should show alkalosis pH and HCO3- (metabolic) values, with
a slightly acidic CO2 (compensatory respiratory acidosis). In this case, pH 7.52 is alkaline
, (normal = 7.35 to 7.45), PaCO2is acidic (normal 35 to 45 mm Hg), and HCO3- is elevated
(normal = 22 to 26 mEq/L). A result of pH 7.78, PaCO2 40 mm Hg, HCO3- 30 mEq/L is
uncompensated metabolic alkalosis. pH 7.35, PaCO2 35 mm Hg, HCO3- 26 mEq/L is within
normal limits. pH 7.25, PaCO2 47 mm Hg, HCO3- 29 mEq/L is compensated respiratory
acidosis.
The nurse would not expect full compensation to occur for which acid-base imbalance?
a) Respiratory acidosis
b) Respiratory alkalosis
c) Metabolic acidosis
d) Metabolic alkalosis Correct Answer: ANS: B
Usually the cause of respiratory alkalosis is a temporary event (e.g., an asthma or anxiety attack).
The kidneys take about 24 hours to compensate for an event, so it is unlikely to see much if any
compensation for respiratory alkalosis. Respiratory acidosis usually results from longer-term
conditions such as chronic lung disease, narcotic overdose, or another event that causes
respiratory depression. The kidneys still do not respond for about 24 hours, but usually the event
is still occurring. For both metabolic imbalances, the respiratory system is quick to attempt to
compensate: however, it may have difficulty sustaining that compensation.
Which laboratory value should the nurse examine when evaluating uncompensated respiratory
alkalosis?
a) PaO2
b) Anion gap
c) PaCO2
d) HCO3- Correct Answer: ANS: C
Uncompensated respiratory imbalances are seen in the PaCO2 levels. PaO2 indicates oxygen
status. Anion gap is used for metabolic acidosis. HCO3- is used to evaluate compensation for
respiratory imbalances or uncompensated metabolic imbalances.
The nurse is caring for a diabetic patient in renal failure. Which laboratory findings would the
nurse expect?
a) pH 7.3, PaCO2 36 mm Hg, HCO3- 19 mEq/L
b) pH 7.5, PaCO2 35 mm Hg, HCO3- 35 mEq/L
c) pH 7.3, PaCO2 47 mm Hg, HCO3- 23 mEq/L
d) pH 7.35, PaCO2 40 mm Hg, HCO3- 25 mEq/L Correct Answer: ANS: A
Patients in renal failure develop metabolic acidosis. The laboratory values that reflect this are pH
7.3, PaCO2 36 mm Hg, HCO3- 19 mEq/L. A laboratory finding of pH 7.5, PaCO2 35 mm Hg,
HCO3- 35 mEq/L is metabolic alkalosis. pH 7.3, PaCO2 47 mm Hg, HCO3- 23 mEq/L is
respiratory acidosis. pH 7.35, PaCO2 40 mm Hg, HCO3- 25 mEq/L values are within normal
range.
A patient with a lower respiratory infection has pH of 7.25, PaCO2 of 55 mm Hg, and HCO3- of
20 mEq/L.
