A nurse is preparing to administer a vaccine to a 4-year-old child. Which of the following vaccines should the nurse administer?

Choice A reason: Using a 20 gauge needle is not the best action, as it is too large for a preschooler's deltoid muscle. A 20 gauge needle has a diameter of 0.9 mm, which may cause more pain and tissue damage. A smaller gauge needle, such as a 23 or 25 gauge, is recommended for intramuscular injections in children.

Choice B reason: Inserting the needle just below the acromion process is not the best action, as it may not reach the deltoid muscle. The acromion process is the bony prominence at the top of the shoulder. The deltoid muscle is located on the lateral aspect of the upper arm, about two finger widths below the acromion process. The nurse should palpate the acromion process and measure the distance to the injection site.

Choice C reason: Inserting the needle at a 15 degree angle is not the best action, as it may not penetrate the muscle tissue. A 15 degree angle is used for intradermal injections, which are given into the dermis, the layer of skin below the epidermis. Intramuscular injections are given into the muscle tissue, which requires a 90 degree angle. The nurse should hold the syringe perpendicular to the skin and insert the needle quickly and firmly.

Choice D reason: Using a 1.8 mm (0.5 in) needle is the best action, as it is the appropriate length for a preschooler's deltoid muscle. The length of the needle should be based on the child's age, weight, and muscle mass. A 1.8 mm (0.5 in) needle is suitable for children who weigh less than 12 kg (26 lb). A longer needle, such as a 2.5 mm (1 in) needle, may be used for children who weigh more than 12 kg (26 lb).

Choice A reason: Tetany is not a typical finding in an infant who is dehydrated. Tetany is a condition where the muscles contract involuntarily and cause spasms or cramps. It is usually caused by low calcium levels or alkalosis, not dehydration.

Choice B reason: Slow, bounding pulse is not a typical finding in an infant who is dehydrated. A slow, bounding pulse may indicate increased intracranial pressure or heart failure, not dehydration. A fast, weak pulse is more likely to occur in an infant who is dehydrated.

Choice C reason: Decreased temperature is not a typical finding in an infant who is dehydrated. A decreased temperature may indicate hypothermia or sepsis, not dehydration. A normal or slightly elevated temperature is more likely to occur in an infant who is dehydrated.

Choice D reason: Irritability is a typical finding in an infant who is dehydrated. Irritability indicates that the infant is uncomfortable and thirsty. It may also be a sign of cerebral dehydration, which can affect the infant's mental status and behavior.