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 A
Explanation
Choice A reason:
A 23-gauge needle is commonly used for venipuncture with a winged infusion set and a small volume syringe like a 5 mL syringe. This size provides a balance between patient comfort and the ease of drawing blood without causing hemolysis or excessive damage to blood cells. It is large enough to allow blood to flow easily into the syringe but small enough to minimize discomfort and the risk of bruising.
Choice B reason:
An 18-gauge needle is quite large and is typically used for situations requiring rapid administration of fluids or for blood donation where larger volumes are collected quickly. It is not ideal for a standard venipuncture, especially with a small syringe, as it can cause more pain and increase the risk of bruising.
Choice C reason:
A 25-gauge needle is on the smaller side and may be used for patients with very fragile veins or for pediatric patients. However, it may not be the best choice for a 5 mL syringe as it could make the blood draw process slower and more difficult, potentially leading to clotting in the needle or syringe.
Choice D reason:
A 27-gauge needle is very small and is typically used for subcutaneous injections, such as insulin injections, rather than for venipuncture. It would be too small for an efficient blood draw with a 5 mL syringe, as it would likely cause the blood to hemolyze or clot before the draw is completed.
Correct Answer is B
Explanation
Choice A Reason:
The red top tube is typically used for serum determinations in chemistry, serology, and blood bank. It contains no additive or may contain a clot activator. The red top tube is not the first choice for capillary puncture order of draw because it is designed for tests that require serum and not whole blood.
Choice B Reason:
The lavender top tube is used for whole blood hematology determinations, as it contains EDTA as an anticoagulant. According to the order of draw for capillary punctures, the EDTA tube should be collected first to ensure adequate volume and accurate hematology test results. This makes the lavender top tube the correct choice for the first collection in this scenario.
Choice C Reason:
The light blue top tube contains sodium citrate and is used for coagulation tests. In venipuncture, it is drawn after the blood culture bottle and before other tubes to prevent contamination with additives from other tubes. However, for capillary punctures, it is not the first choice as hematology tests take precedence.
Choice D Reason:
The royal blue top tube is used for trace element, toxicology, and nutrient determinations². While it may be used for lead and toxicology screens mentioned in the question, it is not the first tube to be drawn in a capillary puncture sequence. The EDTA tube (lavender top) is drawn first to prevent clotting and ensure accurate CBC results.
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