A 60-year-old patient is brought to the emergency department after being found unconscious in a garage with a running car. The patient is conscious but confused, with cherry-red skin coloration. Vital signs are: BP 130/85 mmHg, HR 95 bpm, RR 20/min, SpO2 97% on room air. Which nursing action should be the highest priority?

Administering 100% oxygen via non-rebreather mask is the highest priority to treat carbon monoxide poisoning by displacing CO from hemoglobin, despite normal SpO2 readings. Other interventions like ABG or hyperbaric therapy should not delay oxygen administration.

Core Nursing Explanation This question tests the priority nursing intervention for a patient with suspected Carbon Monoxide (CO) Poisoning. The classic presentation of confusion and cherry-red skin coloration in a patient found in a closed garage with a running car is highly indicative of CO poisoning. Key Concept Analysis: Carbon monoxide binds to hemoglobin with an affinity 200-250 times greater than oxygen, forming Carboxyhemoglobin (COHb). This prevents oxygen from binding, leading to tissue hypoxia. A critical point is that a standard pulse oximeter (SpO2) reads oxygen saturation based on light absorption and cannot differentiate between oxyhemoglobin and carboxyhemoglobin. Therefore, a normal SpO2 reading is misleading and false in CO poisoning. Answer Rationale: The highest priority action is Key Point! Administer 100% oxygen via a non-rebreather mask. This is the immediate, life-saving intervention. High-concentration oxygen competes with CO for hemoglobin binding sites, significantly shortening the half-life of COHb from about 4-5 hours on room air to about 60-90 minutes. This action addresses the root cause of the hypoxia and must not be delayed for diagnostic tests or other treatments. Distractor Analysis:
① Obtain arterial blood gas analysis immediately: While an ABG with co-oximetry is the definitive diagnostic test to measure COHb levels, it is a diagnostic action, not the immediate therapeutic priority. Treatment with oxygen should be initiated first.
② Administer activated charcoal via nasogastric tube: Activated charcoal is used for certain ingested poisons but is not effective for inhaled toxins like carbon monoxide. This intervention is irrelevant to the patient's condition.
④ Prepare the patient for hyperbaric oxygen therapy (HBOT): HBOT is a crucial treatment for severe CO poisoning, as it further reduces the COHb half-life to about 20-30 minutes and helps prevent delayed neurological sequelae. However, preparation for HBOT is a secondary priority. The immediate, on-scene priority is to start high-flow oxygen to begin displacing CO. The nurse would administer oxygen first, then prepare for potential transfer to an HBOT chamber. Related Concepts: The ABCs (Airway, Breathing, Circulation) framework guides priority setting. Here, the patient's airway is patent, but Watch out for confusion! the "Breathing" component is compromised at the cellular level due to impaired oxygen transport. Administering 100% oxygen is the direct intervention to support "Breathing" in this context. Always treat the patient, not the monitor—the normal SpO2 is a dangerous pitfall. Concept Summary

Concept	Key Point
Carbon Monoxide Poisoning	Inhalation of CO gas leads to tissue hypoxia by forming carboxyhemoglobin.
Cherry-Red Skin	A classic but not always present sign caused by high levels of carboxyhemoglobin in the blood.
Pulse Oximeter (SpO2) Limitation	Cannot detect carboxyhemoglobin; reads falsely normal or high.
Immediate Treatment	100% oxygen via non-rebreather mask to displace CO from hemoglobin.
Definitive Diagnosis	Arterial Blood Gas (ABG) with co-oximetry to measure COHb level.
Advanced Treatment	Hyperbaric Oxygen Therapy (HBOT) for severe cases or high-risk patients.

Side-by-Side Comparison!

Intervention	Purpose/Role	Priority in CO Poisoning
100% Oxygen via NRB	First-line treatment to reduce COHb half-life and reverse hypoxia.	Key Point! HIGHEST PRIORITY - Do immediately.
ABG with Co-oximetry	Diagnostic test to confirm COHb level and assess acid-base status.	Important, but do after or concurrently with starting O2 therapy.
Hyperbaric Oxygen (HBOT)	Advanced therapy to further accelerate CO elimination and prevent neurological damage.	Secondary priority for severe cases; requires preparation and transfer.
Activated Charcoal	Adsorbs certain ingested toxins in the GI tract.	Not indicated for inhaled poisons like CO.

Anatomy, Physiology & Pharmacology Points

• Pathophysiology: CO + Hemoglobin → Carboxyhemoglobin (COHb). This bond is strong and shifts the oxygen-hemoglobin dissociation curve to the left, impairing oxygen release to tissues.
• Pharmacology (Oxygen): 100% oxygen acts as a competitive antagonist, displacing CO. It's the specific antidote for this type of poisoning.
• Lab Values: Normal COHb level is < 2% for non-smokers. Levels > 15-20% often cause symptoms; > 25-30% can be severe.

Memory Tips

• CO = Cherry-red & Confused & Car in Closed space (The 3 C's).
• SpO2 is a "CO Liar": Remember that the pulse ox reading is falsely reassuring.
• O2 First, Ask Questions Later: In any suspected inhalation poisoning with hypoxia, high-flow oxygen is almost always the first nursing action.

High-Frequency NCLEX Topics This is a classic NCLEX question testing priority-setting and recognition of a specific toxidrome (symptom complex of a poison). NCLEX loves to present scenarios with normal vital signs or monitor readings that are clinically misleading. The key is to interpret the whole clinical picture, not just one number. Watch Out for Question Variations!

• Symptom Identification: "The nurse identifies cherry-red skin in a patient found in a fire. This finding is most suggestive of poisoning by which substance?" (Answer: Carbon Monoxide).
• Patient Education: "Which statement by a client indicates understanding of discharge teaching after CO poisoning?" (Correct answer would focus on installing CO detectors, proper venting of heaters).
• Evaluation of Therapy: "The nurse is evaluating the effectiveness of 100% oxygen for a patient with CO poisoning. Which finding indicates improvement?" (Answer: Decreased confusion, or a decreasing COHb level on ABG).

Nursing Clinical Practice Guide Clinical Scenario: You are the triage nurse in the ED. EMS brings in Mr. Johnson, found slumped in his car in a closed garage. He is arousable but disoriented to place and time. His skin has an unusual, bright red hue. His wife states he went to warm up the car 30 minutes ago. Nursing Intervention Strategy: 1. Immediate Action (Priority): While guiding the patient to a bed, instruct a colleague to bring a non-rebreather mask and connect it to 100% oxygen. Apply it to the patient immediately. Do not wait for a physician's order—this is a standing protocol for suspected CO poisoning. 2. Assessment: Perform a rapid neurological assessment (e.g., AVPU - Alert, Voice, Pain, Unresponsive; or Glasgow Coma Scale (GCS)). Obtain a full set of vital signs, remembering the SpO2 is unreliable. Ask EMS or family about duration of exposure. 3. Collaboration & Diagnostics: Notify the physician or advanced practice provider. While oxygen is running, draw blood for an ABG with co-oximetry per order. Start an IV line for access. 4. Ongoing Monitoring & Preparation: Continuously monitor neurological status, respiratory effort, and oxygen saturation (understanding its limitation). Gather information to determine if the patient meets criteria for HBOT (e.g., loss of consciousness, neurological signs, high COHb level, pregnancy). Prepare transfer paperwork if HBOT is decided. Patient Safety and Precautions:

• Oxygen Safety: Ensure oxygen is flowing correctly through the non-rebreather mask (bag should inflate). No smoking precautions are critical.
• Neurological Monitoring: CO poisoning can cause delayed neurological sequelae (DNS) days or weeks later, including cognitive deficits, personality changes, and movement disorders. Meticulous documentation of baseline mental status is essential.
• Family Safety: Educate family about the source of CO. The home should be evacuated until the source (faulty furnace, car, generator) is inspected and repaired. This is a public health nursing role.

Nursing Procedure & Medication Flow Procedure: Administering 100% Oxygen via Non-Rebreather Mask 1. Indication: Suspected or confirmed carbon monoxide poisoning, severe hypoxia. 2. Equipment: Oxygen flowmeter, tubing, non-rebreather mask with reservoir bag, oxygen source. 3. Steps: a. Set oxygen flowmeter to 15 L/min (or per protocol to ensure reservoir bag remains inflated). b. Connect tubing and mask. c. Place mask over patient's nose and mouth, secure elastic strap. d. Ensure the reservoir bag inflates and does not completely collapse during inspiration. e. Assess patient's respiratory rate, effort, and color. 4. Patient Education: Explain why the mask is necessary. "Mr. Johnson, this mask is giving you pure oxygen to help clear the bad air from your body. It's very important to keep it on." Medication: Oxygen (O2) - Class: Medical gas, essential medication. - Mechanism: Competitive displacement of CO from hemoglobin. - Dose/Administration: 100% FiO2 via non-rebreather mask at 10-15 L/min. - Monitoring: Mental status, respiratory status, COHb levels (via ABG). A Word from Your Senior Nurse "Remember, in the ED, seconds count with poisoning cases. That normal pulse ox reading is a trap designed to test your critical thinking. You saw the cherry-red skin and the story—trust your nursing assessment over the machine. Putting that oxygen mask on first is the most powerful intervention you can do as a nurse in that moment. It's simple, fast, and saves brain cells. In real practice, you'll be the one initiating this life-saving action based on your assessment, and that autonomy and quick thinking is what makes nursing so vital."