A nurse is caring for a 65-year-old client with carbon monoxide poisoning. Which nursing intervention should be the priority?

Administering 100% oxygen via non-rebreather mask is the priority to displace CO from hemoglobin and prevent tissue hypoxia. Other interventions (monitoring, assessment) are secondary without immediate oxygen therapy.

Clinical Context and Priority Setting

This scenario describes a client with severe carbon monoxide (CO) poisoning. The carboxyhemoglobin (COHb) level of 30% confirms significant exposure, and the presence of lethargy indicates central nervous system depression. A critical concept to recognize is that standard pulse oximetry cannot distinguish carboxyhemoglobin from oxyhemoglobin; therefore, the displayed oxygen saturation of 95% is falsely reassuring and does not reflect the true degree of tissue hypoxia. The immediate priority is to reverse hypoxia and accelerate the elimination of CO.

Analysis of Options

Administering 100% oxygen via a non-rebreather mask is the priority intervention. According to the position statement on CO poisoning management, the cornerstone of treatment is the immediate initiation of normobaric oxygen therapy using 100% oxygen at the highest possible flow rate . This rapidly creates an oxygen concentration gradient that displaces CO from hemoglobin, reducing the half-life of COHb from approximately 4-6 hours on room air to about 60-90 minutes . This directly addresses the underlying pathophysiology of cellular hypoxia and is the most time-sensitive action to prevent further neurological and cardiac injury.

While monitoring cardiac rhythm is important because CO poisoning can cause myocardial depression and arrhythmias, it is a secondary assessment that should occur concurrently with, but not before, the initiation of oxygen therapy. The most effective way to prevent cardiac complications is to correct the hypoxic state immediately.

Assessing neurological status every 15 minutes is a necessary ongoing evaluation, particularly given the risk of delayed neurological sequelae . However, serial assessments do not treat the underlying cause. Neurological improvement is dependent on the rapid reduction of COHb levels through oxygen administration.

Preparing for intubation and mechanical ventilation is a consideration for patients who cannot protect their airway or who fail to respond to normobaric oxygen. A lethargic patient with CO poisoning may improve rapidly with high-flow oxygen, making intubation a potential subsequent step rather than the immediate priority. The initial management algorithm emphasizes maximal non-invasive oxygen delivery first .

Pathophysiological Rationale and Clinical Integration

CO binds to hemoglobin with an affinity approximately 200-250 times greater than oxygen, forming carboxyhemoglobin. This reduces the blood's oxygen-carrying capacity and shifts the oxyhemoglobin dissociation curve to the left, impairing oxygen release at the tissue level. The brain and heart, having the highest oxygen demands, are most vulnerable. This explains why patients can present with syncope, altered mental status, or stroke-like symptoms despite normal pulse oximetry readings . The administration of 100% oxygen is the definitive first-line therapy to competitively reverse this binding. Hyperbaric oxygen therapy (HBOT) is reserved for severe cases with significant neurological or cardiac involvement, such as loss of consciousness or myocardial ischemia, and is considered after initial normobaric oxygen has been started .