After receiving midazolam and fentanyl prior to a bronchoscopy, an older adult's respiratory rate drops to 8 breaths/minute with periods of apnea. The client's arterial blood gas levels are obtained and evaluated. Which laboratory value indicates respiratory depression that can lead to respiratory arrest if left untreated?
Reference Range:
- pH [7.35 to 7.45]
- PaCO2 [35 to 45 mm Hg]
- HCO3 [21 to 28 mEq/L]
- PaO2 [80 to 100 mm Hg]
PaO2 60 mm Hg.
pH 7.30.
HCO3 26 mEq/L (26 mmol/L).
PaCO2 80 mm Hg.
The Correct Answer is D
A. PaO₂ 60 mm Hg: A PaO₂ of 60 mm Hg indicates moderate hypoxemia, which is concerning but not the most direct marker of respiratory depression. It reflects impaired oxygenation, but CO₂ retention is more closely associated with respiratory arrest risk.
B. pH 7.30: A pH of 7.30 shows mild acidemia, which may result from respiratory or metabolic causes. While this indicates some imbalance, it does not specifically point to the severity of respiratory depression as much as rising CO₂ levels do.
C. HCO₃ 26 mEq/L (26 mmol/L): This bicarbonate value is within the normal range and does not suggest acute metabolic compensation or decompensation. It offers limited insight into the acute respiratory depression caused by sedatives like midazolam and fentanyl.
D. PaCO₂ 80 mm Hg: This significantly elevated PaCO₂ indicates severe hypoventilation and respiratory depression. Such a high carbon dioxide level can suppress central respiratory drive, impair consciousness, and quickly progress to respiratory arrest if not promptly reversed.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. Urinary output: Although decreased cardiac output can affect renal perfusion and lower urine output, it is not the immediate assessment after a sudden change in heart rate and pulse quality. Urine output trends over hours, not minutes, making it less useful for acute evaluation.
B. Pedal pulses: Pedal pulses assess peripheral circulation but are not as responsive to acute changes in central perfusion. Diminished pedal pulses may suggest poor perfusion, but the sudden rise in heart rate with weak radial pulse should prompt central hemodynamic assessment first.
C. Heart sounds: Heart sounds provide information about valve function and rhythm but may not detect subtle changes in perfusion status. While auscultation is important, it does not immediately quantify the impact of tachycardia and diminished pulse strength on blood pressure and perfusion.
D. Blood pressure: Assessing blood pressure is the most direct and immediate way to evaluate hemodynamic stability in the setting of sudden tachycardia with a weak pulse. Hypotension may indicate decreased cardiac output or early shock, requiring prompt recognition and intervention.
Correct Answer is D
Explanation
A. Potassium level 3.8 mg/dL (3.8 mmol/L): This potassium level is within the normal range (3.5–5.0 mmol/L) and is unlikely to contribute to the dysrhythmia. Potassium abnormalities can affect cardiac rhythm, but this value does not indicate a risk factor.
B. Sodium level 140 mEq/L (140 mmol/L): This is also within the expected reference range for sodium (136–145 mEq/L). While sodium imbalances can cause neurological changes and fluid shifts, this normal level would not be expected to provoke a dysrhythmia.
C. Oxygen saturation level 97%: An oxygen saturation of 97% indicates adequate oxygenation and perfusion. Hypoxia can lead to arrhythmias, but with this normal value, oxygen deficiency is not a contributing factor.
D. Calcium level 7.2 mg/dL (1.8 mmol/L): This calcium level is below the normal reference range and indicates hypocalcemia, which can lead to cardiac dysrhythmias. Calcium plays a key role in myocardial contractility and electrical conduction, and low levels can provoke arrhythmogenic effects.
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