When calculating total blood volume for a full-term, 2-day-old infant, which of the following information should a phlebotomist consider?
Apgar score
Height
Head circumference
Weight
The Correct Answer is D
Choice A reason:
The Apgar score is a quick test performed on a newborn at 1 and 5 minutes after birth. The 1-minute score determines how well the baby tolerated the birthing process. The 5-minute score tells the healthcare provider how well the baby is doing outside the mother's womb. While it is an important indicator of a newborn's health, it does not directly influence the calculation of total blood volume.
Choice B reason:
Height is a measure of the length of a person's body. In the context of a 2-day-old infant, height is not a practical or necessary measurement for determining blood volume. Blood volume is more closely related to weight than to height, especially in the case of infants.
Choice C reason:
Head circumference is a measurement of the size of a child's head and is used to monitor brain growth. While it can provide valuable information about a child's development, it is not used to calculate blood volume. The total blood volume of an infant is not determined by the size of the head but rather by the overall weight.
Choice D reason:
Weight is the correct factor to consider when calculating total blood volume for a full-term, 2-day-old infant. The standard formula to estimate an infant's total blood volume is approximately 80 {mL/kg} of body weight. Therefore, knowing the infant's weight in kilograms is essential for this calculation.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A Reason:
Positioning the needle at a 45° angle to the skin is not the recommended approach for venipuncture using a butterfly needle on dorsal hand veins. The correct angle for insertion is usually less than 45°, often around 15-30°, to ensure a shallow entry and reduce the risk of going through the vein.
Choice B Reason:
Holding the needle by the wings of the butterfly is the correct technique. This allows for better control and stability during insertion. The wings are designed to be held between the thumb and forefinger, providing an easy grip for the phlebotomist to maneuver the needle with precision.
Choice C Reason:
Instructing the patient to hold the collection tubes is not standard practice and could lead to pre-analytical errors. The phlebotomist should maintain control of the tubes to ensure proper blood flow and fill volume, as well as to prevent contamination or accidents.
Choice D Reason:
Applying the tourniquet at the antecubital area is not specific to the use of a butterfly needle for venipuncture on dorsal hand veins. While a tourniquet is used to engorge the veins and make them more prominent, its placement may vary depending on the selected puncture site and is not the action in question here.

Correct Answer is A
Explanation
Choice A Reason:
The evacuated tube system is designed for the collection of multiple blood specimens using interchangeable tubes. This system utilizes a double-pointed needle, one end of which goes into the patient's vein and the other into a vacuum tube. As the blood is drawn, it automatically fills the tube until the vacuum is exhausted. The phlebotomist can then easily replace the filled tube with another without removing the needle from the patient's vein, allowing for multiple samples to be taken during a single venipuncture.
Choice B Reason:
The hypodermic needle and syringe system is typically used for manual blood draws when the evacuated tube system is not suitable, such as with small or fragile veins. This system does not use interchangeable tubes; instead, the blood is drawn into a syringe and then transferred into the appropriate tubes, which can be time-consuming and increase the risk of hemolysis or contamination.
Choice C Reason:
A winged infusion set, also known as a butterfly needle, is often used for patients with difficult veins. Like the hypodermic needle and syringe system, it does not inherently allow for the use of interchangeable multi-sample tubes. Blood is collected into a syringe or a single tube attached to the butterfly needle, and changing tubes usually requires a new puncture for each sample.
Choice D Reason:
The lancet microcollection system is used for capillary blood collection, typically from a fingerstick or heelstick. It is used for small volume samples and does not accommodate interchangeable multi-sample tubes. This method is commonly used for pediatric patients or when only a small amount of blood is needed.

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