A client is confused and has a severe headache after using a generator in an attached garage. Pulse oximetry reads 99%. Which action should the nurse take first?
1Wait for the carboxyhemoglobin result before beginning oxygen therapy
2Apply low-flow oxygen because pulse oximetry is within range
3Maintain room air and repeat the neurologic assessment in 1 hour
4Administer 100% oxygen while the diagnostic evaluation continues✓ Correct answer
Explanation
The exposure history and neurologic symptoms suggest carbon monoxide poisoning. Conventional pulse oximetry can appear normal because it cannot reliably distinguish oxyhemoglobin from carboxyhemoglobin, so 100% oxygen should begin promptly while testing continues.
Quick answer Start 100% oxygen while the evaluation continues. A normal conventional pulse oximetry value does not exclude carbon monoxide poisoning.
Why this is correct Carbon monoxide impairs oxygen delivery and cellular use, especially in the brain and heart. High-concentration oxygen speeds carbon monoxide elimination, so treatment should not wait for the carboxyhemoglobin result when the history and symptoms are concerning.
Easy analogy or mental picture The pulse oximeter is like a counter that sees occupied seats but cannot tell whether the correct passengers are sitting in them. The comparison explains the misleading reading, but it does not replace carboxyhemoglobin testing or assessment of neurologic and cardiac injury.
Memory hook Generator exposure plus headache or confusion means oxygen now; a normal pulse oximeter can mislead.
NCLEX decision rule When carbon monoxide exposure is plausible and symptoms are present, choose immediate 100% oxygen and continued diagnostic assessment. Do not wait for confirmation or reduce oxygen because the conventional saturation display looks normal.
Why the other choices are wrong Waiting prolongs tissue exposure. Low-flow oxygen under-treats suspected poisoning, and room-air observation ignores an active neurologic emergency.
References
[1]
NCSBN: 2026 NCLEX-RN Test PlanNational Council of State Boards of Nursing
[2]
CDC: Clinical Guidance for Carbon Monoxide PoisoningCenters for Disease Control and Prevention