# A 45-year-old patient is brought to the emergency department after being found unconscious in a garage with a running car. The patient is diagnosed with severe carbon monoxide poisoning. Which nursing intervention should be the highest priority?

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> subject: Adult Health

## 문제

A 45-year-old patient is brought to the emergency department after being found unconscious in a garage with a running car. The patient is diagnosed with severe carbon monoxide poisoning. Which nursing intervention should be the highest priority?

## 보기

1. Administer activated charcoal to prevent further absorption of carbon monoxide
2. Administer 100% oxygen via non-rebreather mask or endotracheal tube **✔ 정답**
3. Initiate IV fluid resuscitation with normal saline at 125 mL/hr
4. Prepare the patient for immediate gastric lavage and decontamination

**정답: 2**

## 해설

Carbon monoxide poisoning requires immediate 100% oxygen administration to displace CO from hemoglobin and restore oxygen delivery. Other interventions like activated charcoal or gastric lavage are not effective for inhaled CO poisoning.

## 심화 해설

Understanding Carbon Monoxide Poisoning

Carbon monoxide (CO) poisoning occurs when CO binds to hemoglobin with an affinity approximately 200-250 times greater than that of oxygen, forming carboxyhemoglobin (COHb). This process severely impairs the blood's oxygen-carrying capacity and shifts the oxyhemoglobin dissociation curve to the left, inhibiting oxygen release at the tissue level. The result is profound cellular hypoxia and metabolic acidosis, which can lead to rapid neurological and cardiac deterioration.

Rationale for the Priority Intervention

The highest priority for a patient with severe CO poisoning is to reverse tissue hypoxia as quickly as possible. Administering 100% oxygen via a non-rebreather mask or endotracheal tube is the cornerstone of initial management. This intervention, known as normobaric oxygen therapy (NBOT), works by creating a high partial pressure gradient of oxygen in the alveoli. This gradient competitively displaces CO from hemoglobin, significantly reducing the half-life of COHb from approximately 4-6 hours on room air to about 60-90 minutes [2]. The immediate goal is to restore adequate oxygen delivery to the brain and heart, the organs most vulnerable to hypoxic injury. While the provided research explores advanced therapies like hyperbaric oxygen therapy (HBOT) and continuous extracorporeal hyperoxygenation therapy (cEHT) for severe or refractory cases, these are secondary considerations that follow the immediate initiation of high-flow oxygen [1, 2]. The study by Yüceer reinforces that NBOT is the standard initial treatment, with decisions about HBOT being made subsequently based on neurological and cardiac determinants [2].

Why Other Options Are Incorrect

- Option 1 (Administer activated charcoal): Activated charcoal is ineffective for inhaled toxins like CO. It is used for gastrointestinal decontamination following the ingestion of certain substances, but it has no role in binding or preventing the absorption of an inhaled gas.

- Option 3 (Initiate IV fluid resuscitation): While fluid resuscitation may be a supportive measure to manage hypotension and maintain cardiac output, it does not address the primary problem of CO binding to hemoglobin. The immediate, life-saving priority is to enhance CO elimination and oxygen delivery, not volume expansion.

- Option 4 (Prepare for gastric lavage): Gastric lavage is a decontamination procedure for ingested poisons. It is completely irrelevant and contraindicated in a poisoning case where the route of exposure is inhalation.References (research sources)

- [2]Neurological and Cardiac Determinants of Hyperbaric Oxygen Therapy in Carbon Monoxide Poisoning: A Retrospective Cohort Study.Research articleYüceer Ö. (2026) · DOI: 10.2147/ijgm.s604040

## 임상 시나리오

Clinical Management of Severe Carbon Monoxide Poisoning

The immediate priority is to reverse hypoxia and accelerate CO elimination. Follow these steps for a patient with altered consciousness and confirmed or strongly suspected CO exposure.

1. Immediate Airway and Breathing Support

- Ensure a patent airway. In an unconscious patient, intubate early for airway protection and to deliver 100% oxygen.

- Administer 100% oxygen via a non-rebreather mask if the patient is breathing spontaneously and protecting their airway. Target flow rates of 15 L/min to keep the reservoir bag inflated.

2. Oxygen Therapy Goals and Monitoring

- Continue high-flow oxygen until the carboxyhemoglobin (COHb) level is below 3-5% and symptoms resolve.

- Monitor pulse oximetry with caution; standard SpO2 readings are falsely normal in CO poisoning because they cannot distinguish carboxyhemoglobin from oxyhemoglobin.

- Obtain an arterial blood gas (ABG) with co-oximetry to measure the true COHb level and assess for metabolic acidosis.

3. Cardiac and Neurological Monitoring

- Place the patient on continuous cardiac monitoring. Myocardial hypoxia can cause dysrhythmias and ischemia.

- Perform serial neurological assessments (GCS, pupil reactivity) to detect cerebral edema or deterioration.

4. Disposition and Advanced Therapies

- Consult a hyperbaric medicine specialist or poison control center (e.g., 1-800-222-1222) for patients with loss of consciousness, COHb > 25%, neurological deficits, or cardiac ischemia.

- Hyperbaric oxygen therapy (HBOT) may be indicated to further reduce the COHb half-life and mitigate delayed neurological sequelae.

**Nursing Priority:** Never delay the initiation of 100% oxygen therapy to obtain diagnostics or arrange transfer. Time to correction of hypoxia is the critical determinant of outcome.

## 핵심 개념

- **Carboxyhemoglobin (COHb)** — A stable complex formed when carbon monoxide binds to hemoglobin, reducing the blood's oxygen-carrying capacity.
- **Normobaric Oxygen Therapy (NBOT)** — Administration of 100% oxygen at normal atmospheric pressure to accelerate the elimination of carbon monoxide from the body.
- **Non-rebreather Mask** — A device that delivers high concentrations of oxygen (60-90%) and prevents rebreathing of exhaled air, used in emergencies.
- **Tissue Hypoxia** — A condition where tissues are deprived of adequate oxygen supply, leading to cellular dysfunction and potential organ damage.
- **Oxyhemoglobin Dissociation Curve** — A graph showing the relationship between oxygen partial pressure and hemoglobin saturation; CO poisoning shifts this curve to the left, impairing oxygen release.

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