The nurse is caring for a client whose arterial blood gas reveals fully compensated metabolic acidosis. Which results are consistent with this finding?
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Table 9.9 Normal Arterial Blood Gas Values |
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ABG Value. Normal Value |
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pH 7.35-7.45 |
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PaCO2 35-45 mmHg |
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HCO3- 22-26mEq/L |
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Base excess -2 to +2 |
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PaO2 80-95 mmHg |
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SaO2 >95% |
pH 7.36, Pa02 98 mmHg, PaCO2 27 mmHg, HCO3 16 mEq/L, 02 sat 99%
pH 7.47, Pa02 91 mmHg, PaCO2 52 mmHg. HCO3 30 mEg/L, 02 sat 96%
pH 7.45, P302 86 mmHg, PaCO2 56 mmHg, HCO3 28 mEg/L, 02 sat 94%
PH 7.32, PaO2 88 mmHg. PaCO2 54 mmHg. HCO3 29 mEq/L. 02 sat 94%
The Correct Answer is A
A. pH 7.36, PaO2 98 mmHg, PaCO2 27 mmHg, HCO3 16 mEq/L, O2 sat 99%: This set of ABG results is consistent with fully compensated metabolic acidosis. pH 7.36: This is within the normal range (7.35-7.45), indicating that compensation has occurred, as the pH has returned to normal levels. PaCO2 27 mmHg: The PaCO2 is low, suggesting that the respiratory system has compensated for the metabolic acidosis by increasing ventilation to excrete CO2, thus reducing the acid load. HCO3 16 mEq/L: The bicarbonate level is low, which is consistent with metabolic acidosis as the primary disturbance. The PaO2 and O2 saturation are normal, indicating adequate oxygenation. Since the pH is within the normal range and the PaCO2 and HCO3 levels reflect the compensatory changes needed to correct the metabolic acidosis, this is a case of fully compensated metabolic acidosis.
B. pH 7.47, PaO2 91 mmHg, PaCO2 52 mmHg, HCO3 30 mEq/L, O2 sat 96%:
This result indicates alkalosis rather than acidosis. The pH is alkalotic (7.47), and PaCO2 is elevated (52 mmHg), which suggests respiratory acidosis as the primary disturbance. The HCO3 is also high (30 mEq/L), which is consistent with metabolic compensation for respiratory acidosis, not for metabolic acidosis. Therefore, this is not consistent with fully compensated metabolic acidosis.
C. pH 7.45, PaO2 86 mmHg, PaCO2 56 mmHg, HCO3 28 mEq/L, O2 sat 94%:
The pH is normal, but PaCO2 is elevated (56 mmHg), indicating respiratory acidosis rather than metabolic acidosis. The HCO3 is also elevated (28 mEq/L), which is consistent with compensation for respiratory acidosis, not metabolic acidosis. This result suggests respiratory acidosis with compensated metabolic alkalosis rather than metabolic acidosis.
D. pH 7.32, PaO2 88 mmHg, PaCO2 54 mmHg, HCO3 29 mEq/L, O2 sat 94%:
The pH of 7.32 indicates acidosis, but it is not within the normal range, so this is not fully compensated. The PaCO2 is elevated (54 mmHg), indicating respiratory acidosis, and the HCO3 is elevated (29 mEq/L), showing metabolic compensation. However, since the pH has not yet returned to normal (it remains acidotic), this is an example of partially compensated respiratory acidosis, not fully compensated metabolic acidosis.
respiratory acidosis, not fully compensated metabolic acidosis.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. Guidewire-induced dysrhythmia: Guidewire-induced dysrhythmia can occur if the guidewire or catheter irritates the heart during insertion, particularly when the catheter is placed in the central venous system. While this can lead to arrhythmias, it is typically more immediate and occurs during the procedure itself. The symptoms of dysrhythmia (e.g., irregular heartbeat) would more likely present right after insertion or during the manipulation of the guidewire. The signs of restlessness, JVD, and tachycardia observed 30 minutes after placement are more suggestive of a pneumothorax than of a guidewire-induced dysrhythmia.
B. Pneumothorax: Pneumothorax is a potential complication of central venous catheter (CVC) placement, particularly when the catheter is inserted into the subclavian vein. The right subclavian vein is located near the apex of the lung, so inadvertent puncture of the lung during catheter placement can lead to air entering the pleural space, causing a pneumothorax. The symptoms of pneumothorax may include restlessness, tachycardia, jugular vein distention (JVD), and respiratory distress. A heart rate of 120 beats per minute is consistent with tachycardia due to hypoxia or distress, and JVD can be a sign of increased intrathoracic pressure or impaired venous return, which occurs with a pneumothorax. These symptoms warrant immediate assessment for pneumothorax, which can be confirmed with a chest x-ray.
C. Pulmonary infarction: Pulmonary infarction occurs when a blockage in the pulmonary arteries prevents blood flow to lung tissue, resulting in tissue death. This can be caused by a pulmonary embolism or other issues, but it is not a typical complication of central venous catheter placement. The symptoms described (restlessness, JVD, and tachycardia) are more consistent with a pneumothorax than a pulmonary infarction, which would likely cause chest pain, hemoptysis, or dyspnea rather than these signs.
D. Venous thrombosis: While venous thrombosis (or clot formation) is a potential complication of central venous catheter placement, it typically manifests as swelling, redness, or pain at the catheter insertion site, rather than with the systemic symptoms of restlessness, tachycardia, and JVD. Venous thrombosis could cause some of the described symptoms in the long term, but it is less likely to be the cause of acute symptoms 30 minutes post-procedure. The immediate concern in this case is more likely to be pneumothorax, which can occur more suddenly and cause these symptoms.Top of FormBottom of Form
Correct Answer is B
Explanation
A. Partially compensated metabolic alkalosis:
Metabolic alkalosis is characterized by elevated bicarbonate levels (HCO3), but in this case, the HCO3 is elevated (29 mEq/L), which suggests alkalosis. However, the PaCO2 is elevated at 47 mmHg, which is more consistent with a respiratory problem. A fully or partially compensated metabolic alkalosis would show a normal or low PaCO2 (due to respiratory compensation). Therefore, this option does not fit the ABG results.
B. Partially compensated respiratory acidosis: In this case, the pH is 7.17, which is low and indicates acidosis. The PaCO2 is 47 mmHg, which is elevated (normal range: 35-45 mmHg), indicating that the respiratory system is contributing to the acidosis. The HCO3 is 29 mEq/L, which is elevated (normal range: 22-26 mEq/L), suggesting a compensatory response from the kidneys to retain bicarbonate in an attempt to buffer the acidosis. Since the pH is still below normal and has not yet returned to the normal range (7.35-7.45), this suggests that the compensation is partial and the primary issue is respiratory acidosis.
C. Fully compensated metabolic alkalosis:
This answer is incorrect because metabolic alkalosis is not the primary disturbance here. Also, for a condition to be fully compensated, the pH would need to be within the normal range (7.35-7.45). Since the pH is 7.17, the condition is not fully compensated.
D. Fully compensated respiratory acidosis:
For fully compensated respiratory acidosis, the pH should be within the normal range, as the kidneys would have fully compensated for the elevated PaCO2. Since the pH is 7.17, this is a sign of partial compensation, not full compensation. Therefore, this option is incorrect.
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