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Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Carbon Monoxide Poisoning

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In one line

·Carbon monoxide sticks to hemoglobin 200 times tighter than oxygen does, so your blood cannot deliver oxygen to your cells.

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Normal physiology

·Hemoglobin is a protein inside red blood cells that picks up oxygen in your lungs and releases it to every cell in your body. Picture it like a delivery truck that loads oxygen, drives through blood vessels, and unloads where cells are hungry.

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What goes wrong

·Carbon monoxide from fires, car exhaust, broken heaters, or generators sticks to hemoglobin 200 times tighter than oxygen does and refuses to let go. At the same time, it poisons the power factories inside cells so they cannot use oxygen even if some arrives.

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Hallmark signs

·Headache that feels dull and throbbing
·Feeling dizzy or lightheaded
·Nausea or throwing up
·Confusion or trouble thinking clearly
·Chest pain or a tight feeling in the chest
·Shortness of breath or feeling like you cannot get enough air
·Weakness or tired muscles
·Passing out or losing consciousness

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Red flags · escalate now

·Passing out or becoming unresponsive
·New confusion or trouble thinking clearly
·Chest pain or feeling like the heart is squeezing
·Seizures or jerking movements
·Multiple people in the same building getting sick at the same time

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Workup

·Carboxyhemoglobin level (CoHb) on arterial or venous blood gas
·Arterial blood gas (ABG) with pH, PaO₂, and lactate
·Troponin I or troponin T
·12-lead electrocardiogram (ECG)
·Pregnancy test (urine or serum hCG) in all women of childbearing age
·Pulse oximetry (SpO₂)
·Brain MRI with diffusion-weighted imaging (DWI) and T2/FLAIR sequences if delayed neurologic symptoms appear days to weeks after exposure
·Complete blood count (CBC) with hemoglobin

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Treatment

·100% oxygen via tight-fitting non-rebreather mask at 15 liters per minute, continued for at least 4 to 6 hours or until CoHb drops below 5% and symptoms resolve
·Hyperbaric oxygen (HBO) therapy at 2.5 to 3 atmospheres of pressure for 90 minutes, sometimes repeated once or twice over the next 24 hours in severe cases
·Hyperbaric oxygen is recommended (per current guidelines from the American Heart Association and the Undersea and Hyperbaric Medical Society) if any of these are present: loss of consciousness at any point during or after exposure, CoHb > 25%, pregnancy with CoHb > 15% or any neurologic symptoms (even mild confusion or headache), evidence of heart starved blood flow (ischemia) (chest pain, ECG changes, or troponin elevation), or persistent moderate-to-severe neurologic symptoms (confusion, seizure, focal weakness, vision changes) despite 4 to 6 hours of 100% oxygen at normal pressure
·Treat coexisting cyanide poisoning with hydroxocobalamin 5 grams IV over 15 minutes (may repeat once) if the exposure was from a structural fire, enclosed-space fire, or burning plastics, synthetic materials, or foam
·Treat smoke inhalation lung injury with humidified oxygen, nebulized albuterol 2.5 to 5 mg every 4 hours as needed for wheezing, and close monitoring of the airway; intubate early (within the first 2 to 4 hours) if a high-pitched noise on breathing in (stridor) (high-pitched breathing sound), severe face or mouth burns, soot in the nose or throat, or rapidly worsening breathing are present
·Remove the patient and everyone else from the contaminated environment immediately, ventilate the space, and contact the fire department or gas company to inspect the source (furnace, water heater, generator) and measure carbon monoxide levels in the air
·Arrange neurology or neuropsychology follow-up 4 to 6 weeks after discharge to screen for delayed neurologic after-effects (sequelae) (problems with memory, attention, executive function, mood, and movement)

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NCLEX trap

·Always ask: Did more than one person in the same room or building get sick at the same time? If yes, think carbon monoxide poisoning first. Get everyone out into fresh air and send them to the hospital for oxygen and a blood test called carboxyhemoglobin level. Carbon monoxide is invisible and has no smell, so people often mistake it for the flu.
·Carbon monoxide can damage the brain days or even weeks later, even after the person feels fine right now. Anyone who had confusion, passing out, or trouble thinking needs high-pressure oxygen treatment in a special chamber to protect the brain from late damage. Always arrange follow-up care.
·Carboxyhemoglobin over 25 percent always needs high-pressure oxygen treatment in a special chamber called a hyperbaric chamber. Any level over 15 percent in a pregnant woman needs the chamber, too. And any person with brain symptoms like confusion, passing out, or vision changes needs the chamber no matter what the number is, because those symptoms mean the brain is already being hurt.
·A baby growing inside the mother gets hurt by carbon monoxide even when the mother feels okay. The baby's blood holds onto carbon monoxide longer than the mother's blood does, so the baby is in danger even after the mother feels better. Pregnant women with carboxyhemoglobin over 15 percent must get high-pressure oxygen treatment to protect the baby.
·Cherry-red skin is very rare in carbon monoxide poisoning and usually only shows up after someone has died. Most people with carbon monoxide poisoning look totally normal. Do not wait for this sign. Diagnose carbon monoxide poisoning by asking about the setting (group sickness, broken heater, running car in a closed garage, house fire) and by checking the carboxyhemoglobin blood level.
·Delayed brain damage can appear 2 to 8 weeks after carbon monoxide poisoning. Ask the patient about new memory problems, trouble walking, mood swings, trouble thinking clearly, or personality changes. These late problems are real and happen because carbon monoxide hurts the tiny power factories inside brain cells called mitochondria (the parts that make energy for cells to work). The patient needs a doctor visit and possibly a brain scan to check for damage.

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