A nurse in an emergency department is assisting with the care of a client who is unconscious and has trauma to multiple systems following a motor vehicle crash. Which of the following actions should the nurse take first?

Choice A reason: The reservoir is the environment or habitat where the infectious agent lives and multiplies. The client's mouth is not a reservoir, but rather a part of the susceptible host. The reservoir for hepatitis A is usually the feces of an infected person.

Choice B reason: The susceptible host is the person who is at risk of getting the infection. The client's mouth is not a susceptible host, but rather a part of the susceptible host. The susceptibility to hepatitis A depends on factors such as age, immunity, hygiene, and exposure.

Choice C reason: The portal of entry is the opening or route through which the infectious agent enters the susceptible host. The client's mouth is a portal of entry, as it is where the contaminated food entered the client's body and caused the infection. Hepatitis A is transmitted through the fecaloral route, meaning that the virus is ingested from contact with objects, food, or water contaminated by the feces of an infected person.

Choice D reason: The infectious agent is the microorganism that causes the infection. The client's mouth is not an infectious agent, but rather a portal of entry for the infectious agent. The infectious agent for hepatitis A is a virus that affects the liver and causes inflammation, jaundice, and fever.

Choice A reason: This action is correct because airway protection is the first priority for a client who is unconscious and has trauma to multiple systems. The nurse should assess the client's airway patency, breathing, and oxygenation, and intervene as needed to secure and maintain the airway. The nurse should also monitor the client for signs of aspiration, bleeding, or obstruction, and suction the airway as needed.
Choice B reason: This action is incorrect because stabilizing cardiac arrhythmias is not the first priority for a client who is unconscious and has trauma to multiple systems. The nurse should assess the client's circulation, blood pressure, and pulse, and intervene as needed to treat any arrhythmias, shock, or hemorrhage. However, this is not a priority over the client's airway, which is essential for survival.
Choice C reason: This action is incorrect because preventing musculoskeletal disability is not the first priority for a client who is unconscious and has trauma to multiple systems. The nurse should assess the client's mobility, sensation, and alignment, and intervene as needed to prevent or treat any fractures, dislocations, or nerve injuries. However, this is not a priority over the client's airway, which is essential for survival.
Choice D reason: This action is incorrect because decreasing intracranial pressure is not the first priority for a client who is unconscious and has trauma to multiple systems. The nurse should assess the client's level of consciousness, pupillary response, and neurological status, and intervene as needed to prevent or treat any increased intracranial pressure, cerebral edema, or brain injury. However, this is not a priority over the client's airway, which is essential for survival.