For a client diagnosed with carbon monoxide poisoning, what is the nurse's first action?

In the case of carbon monoxide poisoning, administering 100% oxygen by mask is the first and most crucial action for the nurse to take. Carbon monoxide (CO) binds to hemoglobin in the blood with a much higher affinity than oxygen, leading to reduced oxygen delivery to tissues and potential hypoxia. By providing 100% oxygen, the body is able to displace carbon monoxide from hemoglobin, effectively reducing its half-life and aiding in the elimination of CO from the blood. This intervention is paramount as it directly addresses the hypoxic condition caused by CO binding.

This immediate provision of oxygen is crucial in stabilizing the patient and preventing further complications associated with oxygen deprivation to vital organs. Other interventions, while important in the overall management of carbon monoxide poisoning, do not address the immediate life-threatening aspects as effectively. For instance, gastric lavage, maintaining body temperature, or seeking psychiatric referrals do not rectify the central issue of impaired oxygen transport and tissue hypoxia caused by carbon monoxide exposure. Thus, the administration of 100% oxygen is the critical first step in the management of carbon monoxide poisoning.