Ch. 10 ABG Interpretation (Test 2) Flashcards
Which of the following conditions shifts the HbO2 dissociation curve to the right?
A. Hypercapnia
B. Hypothermia
C. Alkalemia
D. HbCO
Hypercapnia
A shift of the oxyhemoglobin curve to the right indicates that Hb has less affinity for O2 and releases it more readily to the tissues, thus increasing tissue oxygenation. Conditions that shift the curve to the right include hypercapnia, acidemia, hyperthermia, and increased levels of 2,3-DPG.
A patient with a 2 L/min nasal cannula has the following ABG results:
pH 7.51
PaCO2: 27 mm Hg
PaO2: 62 mm Hg
HCO3: 23 mEq/L
These results indicate which of the following conditions?
A. Uncompensated respiratory acidosis
B. Chronic respiratory alkalosis
C. Compensated metabolic alkalosis
D. Acute respiratory alkalosis
Acute respiratory alkalosis
The respiratory therapist has received an order to obtain an ABG sample from a patient, but an Allen test indicates collateral circulation is not present in the right wrist. At this time, the therapist would:
A. Obtain blood from the right radial artery.
B. Obtain blood from the right brachial artery.
C. Wait for the physician to evaluate collateral circulation.
D. Check collateral circulation in the left wrist.
Check collateral circulation in the left wrist.
The following ABGs have been recorded for a patient on a 35% air-entrainment mask:
pH 7.51
PaCO2: 42 mm Hg
PaO2: 79 mm Hg
HCO3: 33 mEq/L
What is the correct interpretation of this blood gas?
A. Partially compensated respiratory alkalosis
B. Fully compensated metabolic alkalosis
C. Uncompensated respiratory alkalosis
D. Uncompensated metabolic alkalosis
Uncompensated metabolic alkalosis
The respiratory therapist is reviewing ABGs obtained earlier in the day from a patient on a 35% air- entrainment mask. The ABG values are as follows:
pH 7.43
PaCO2 29 torr
PaO2 70 torr
HCO3 18 mEq/L
What is the correct interpretation of this blood gas?
A. Partially compensated metabolic acidosis, normal oxygenation
B. Fully compensated respiratory alkalosis, mild hypoxemia
C. Uncompensated respiratory alkalosis, normal oxygenation
D. Fully compensated metabolic acidosis, mild hypoxemia
Fully compensated respiratory alkalosis w/ mild hypoxemia
The following blood gases are obtained on a severe, cyanotic COPD patient on a 2 L/min nasal cannula:
pH 7.51
PaCO2 29 torr
PaO2 155 torr
HCO3 34 mEq/L
Which of the following most likely accounts for these ABG values?
A. The patient’s cannula flow was higher than 2 L/min at the time of the arterial stick
B. There is air in the blood sample
C. The blood was inadvertently obtained from a vein
D. These represent normal blood gases for a severe COPD patient
There is air in the blood sample
These are certainly not ABG results we would expect to observe in a COPD patient. With the high PaO2 and low PaCO2, you should suspect air in the sample. Even if the patient was on more than 2 L/min, that wouldn’t account for the low PaCO2.
A patient on a mechanical ventilator has the following ABG results:
pH 7.27
PaCO2 28 torr
PaO2 88 torr
HCO3 27 mEq/L
Based on this data, the respiratory therapist should recommend which of the following?
A. Increase the VT.
B. Decrease the ventilator rate.
C. Repeat the blood gas evaluation since these results indicate a laboratory error.
D. Decrease the FiO2.
Repeat the blood gas evaluation since these results indicate a laboratory error.
While this question may appear to be a ventilator management question, it’s really directed at this erroneous blood gas result. Since the pH in this question is acidotic, the PaCO2 must be high or the HCO32 must be low, neither of which is the case. This result is not possible, so the blood gas must be repeated.
What are common sites for ABGs
- radial
- femoral
- dorsalis pedis arteries
Air bubbles affect blood gas levels and should be removed from the syringe. Air in the blood causes increased PaO2 levels (as high as the 150s torr range) and decreased PaCO2 levels.
KNOW
The PaO2 is the portion of O2 that is dissolved in the
plasma of the blood.
This value is often compared with PaO2 to determine the P(A-a)O2 gradient, which refers to the difference between
alveolar O2 tension and arterial O2 tension.
The norml gradient on room air is
4 to 12 mm Hg
The majority of O2 in the blood is bound to what
Hb
HbO2 Dissociation Curve
1. This curve plots the relationship between PaO2 and SaO2 and the affinity that Hb has for O2 at various saturation levels.
KNOW
The flat portion of the curve indicates that at
PaO2 levels above 60 mm Hg saturation rises slowly
