A patient had a craniotomy one hour after a motor vehicle accident. The nurse evaluates pupillary response to:

Choice A reason: This is incorrect. After the age of 60, the plasma volume decreases and there is a decreased ability to fight infections. The decrease in plasma volume reduces the blood flow and oxygen delivery to the tissues, which impairs the immune function.

Choice B reason: This is correct. Healthy bone marrow function decreases with aging, which lowers the immune response to infection. The bone marrow produces fewer white blood cells, which are essential for fighting infections. The older adult also has a reduced response to vaccines, which makes them more susceptible to infections.

Choice C reason: This is incorrect. Older adults have an underactive antibody response to vaccines. This means that they do not produce enough antibodies to protect themselves from the pathogens that the vaccine is supposed to prevent.

Choice D reason: This is incorrect. An older person's blood is more prone to clotting, but this does not affect the infection-fighting cells. The infection-fighting cells can still travel through the blood vessels and reach the source of infection. However, the increased risk of clotting can lead to other complications such as stroke or heart attack.

Choice A reason: Assessing the patient for potential visual deficits is not the primary purpose of evaluating pupillary response. Visual deficits may result from damage to the optic nerve or the occipital lobe, but they are not directly related to pupillary response.

Choice B reason: Assessing the patient's level of consciousness is an important part of the neurological assessment, but it is not done by evaluating pupillary response alone. Level of consciousness is determined by observing the patient's responsiveness to verbal and physical stimuli, as well as their orientation to person, place, time, and situation.

Choice C reason: Assessing the patient for increased intracranial pressure is the best explanation for evaluating pupillary response. Increased intracranial pressure is a life-threatening condition that can result from brain swelling, bleeding, or infection. It can cause compression of the brainstem and the cranial nerves, leading to changes in pupillary size, shape, and reactivity. Pupillary response is a sensitive indicator of intracranial pressure and brainstem function.

Choice D reason: Assessing the patient for cerebrospinal fluid leakage is not the main reason for evaluating pupillary response. Cerebrospinal fluid leakage can occur after a craniotomy due to a tear in the dura mater, the membrane that covers the brain and spinal cord. It can cause symptoms such as headache, nausea, vomiting, and meningitis. However, it does not affect pupillary response unless it causes increased intracranial pressure.