The nurse provides care for several clients. Which client is most at risk to develop metabolic acidosis?

Choice A reason: Decrease in sympathetic nervous system outflow is the best explanation because it is a condition that affects the regulation of blood pressure, heart rate, and skin temperature. The sympathetic nervous system is a part of the autonomic nervous system, which is the part of the nervous system that controls the involuntary functions of the body, such as breathing, digestion, and circulation. The sympathetic nervous system is responsible for the fight-or-flight response, which prepares the body for action or danger, by increasing the blood pressure, heart rate, and skin temperature. The sympathetic nervous system is composed of nerve fibers that originate from the thoracic and lumbar regions of the spinal cord, which are the middle and lower parts of the spinal cord. A complete spinal cord injury at the C3 to C4 level is a condition where the spinal cord is severed or damaged at the neck, which interrupts the communication between the brain and the rest of the body. A complete spinal cord injury at the C3 to C4 level can cause the loss of sympathetic nervous system outflow, which means that the nerve impulses that normally stimulate the blood vessels, the heart, and the sweat glands are reduced or absent. This can result in hypotension, which is a low blood pressure, bradycardia, which is a slow heart rate, and warm and dry skin, which are the observations noted in the client.

Choice B reason: Decreased fluid volume in the intravascular space is not the best explanation because it is a condition that affects the amount of fluid in the blood vessels, which can be caused by various factors, such as dehydration, bleeding, or vomiting. Decreased fluid volume in the intravascular space can cause hypotension, which is a low blood pressure, but it can also cause tachycardia, which is a fast heart rate, and cool and clammy skin, which are not the observations noted in the client.

Choice C reason: The effects of opiate medication administration is not the best explanation because it is a condition that affects the pain perception and the central nervous system, which can be caused by various types of medications, such as morphine, codeine, or oxycodone. The effects of opiate medication administration can cause hypotension, which is a low blood pressure, and bradycardia, which is a slow heart rate, but it can also cause respiratory depression, which is a slow and shallow breathing, and miosis, which is a constriction of the pupils, which are not the observations noted in the client.

Choice D reason: Onset of acute systemic bacterial infection is not the best explanation because it is a condition that affects the immune system and the whole body, which can be caused by various types of bacteria, such as staphylococcus, streptococcus, or salmonella. Onset of acute systemic bacterial infection can cause hypotension, which is a low blood pressure, but it can also cause fever, which is a high body temperature, and chills, which are sensations of coldness and shivering, which are not the observations noted in the client.

Choice A reason: Decreased dietary intake of proteins and vegetables is not the best explanation because it is a factor that affects the nutritional status, not the immune system. Nutritional status is important for maintaining the health and function of the body, but it does not directly cause an increased risk of infection. Proteins and vegetables are sources of essential nutrients, such as amino acids, vitamins, minerals, and antioxidants, that support the growth and repair of the tissues and the prevention of oxidative stress.

Choice B reason: Decreased T cell function and antibody response is the best explanation because it is a factor that affects the immune system, which is the body's defense mechanism against foreign invaders, such as bacteria, viruses, and fungi. The immune system consists of two main components: the innate immunity and the adaptive immunity. The innate immunity is the first line of defense that provides a general and rapid response to any potential threat. The adaptive immunity is the second line of defense that provides a specific and long-lasting response to a particular antigen. T cells and antibodies are part of the adaptive immunity, which recognizes and remembers the antigens that have previously infected the body and eliminates them more efficiently. However, as people age, the T cell function and the antibody response decline, making the older adults more susceptible to infections, especially those that are new or unfamiliar to the body.

Choice C reason: Atrophy of the bone marrow and spleen is not the best explanation because it is a factor that affects the production and storage of immune cells, not the function and response. The bone marrow is the soft tissue inside the bones that produces the blood cells, including the white blood cells, which are the main components of the immune system. The spleen is an organ that filters the blood and removes the old or damaged blood cells, as well as stores some of the white blood cells and platelets. As people age, the bone marrow and the spleen shrink and lose some of their ability to produce and store the immune cells, which can reduce the number and diversity of the immune cells available to fight infections. However, this does not necessarily affect the function and response of the immune cells that are already circulating in the blood.

Choice D reason: Impaired absorption of vitamin B12 is not the best explanation because it is a factor that affects the nervous system and the blood cells, not the immune system. Vitamin B12 is a water-soluble vitamin that is essential for the synthesis of DNA, the maintenance of the myelin sheath, and the formation of red blood cells. As people age, the absorption of vitamin B12 decreases due to the reduced secretion of stomach acid and intrinsic factor, which are needed to break down and bind to the vitamin B12 in the food. This can lead to vitamin B12 deficiency, which can cause symptoms such as fatigue, weakness, numbness, tingling, memory loss, and anemia. Anemia is a condition where the blood has a low level of hemoglobin, which is the protein that carries oxygen in the red blood cells. Anemia can affect the oxygen delivery to the tissues, but it does not directly cause an increased risk of infection.