Blood collection tubes fill correctly during venipuncture due to which of the following factors?
The high pressure in the arterial system
The high pressure in the venous system
The positive pressure created by the tourniquet
The negative pressure within the tube
The Correct Answer is D
Choice A reason:
The high pressure in the arterial system is not a factor in the filling of blood collection tubes during venipuncture. Arterial blood is not typically collected using evacuated tubes; these are used for venous blood collection, where the pressure is lower.
Choice B reason:
While the venous system does have pressure that aids in blood flow, it is not the high pressure that causes blood collection tubes to fill. Venous pressure is relatively low compared to arterial pressure, and on its own, it is not sufficient to fill the vacuum tubes used in venipuncture.
Choice C reason:
The positive pressure created by the tourniquet can help engorge the veins, making them easier to access, but it does not directly cause the blood collection tubes to fill. The tourniquet's role is to assist in vein visualization and palpation rather than in the filling of the tube.
Choice D reason:
The negative pressure within the tube is the correct factor that causes blood collection tubes to fill during venipuncture. When the needle punctures the patient's vein and then the tube stopper, the vacuum in the tube pulls blood into it until the vacuum is exhausted or the tube is filled. This is why it is essential not to allow the tube contents to contact the stopper, as backflow into the venous system can cause adverse reactions.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A Reason:
Anchoring a vein is a technique used to stabilize the vein during venipuncture to prevent it from rolling. The recommended practice is to anchor the vein 1 to 2 inches below the puncture site. This is done by applying gentle traction on the skin downward with the thumb, which helps to stabilize the vein and facilitate the insertion of the needle.
Choice B Reason:
Anchoring 1 to 2 inches above the puncture site is not the standard practice. This position would not provide the necessary tension on the vein to prevent it from rolling and could make the venipuncture more difficult.
Choice C Reason:
Anchoring 2 inches left of the puncture site does not provide the correct angle or tension for stabilizing the vein for a venipuncture and is not a recommended technique.
Choice D Reason:
Anchoring 1 inch right of the puncture site is also not a recommended practice. Similar to anchoring to the left, this does not provide the proper stabilization needed for a successful venipuncture.
Correct Answer is A
Explanation
Choice A reason:
Mechanical safety is a critical aspect of laboratory inspections, especially when focusing on equipment maintenance logs. These logs are essential for ensuring that all mechanical equipment is functioning correctly and safely. Regular maintenance and inspection can prevent mechanical failures that could lead to workplace accidents or compromise the integrity of experiments.
Choice B reason:
Chemical safety is undoubtedly important in a laboratory setting; however, it is not the primary focus when the inspection is centered on equipment maintenance logs. Chemical safety would involve the proper storage, handling, and disposal of chemicals, which is a separate concern from the mechanical functioning of equipment.
Choice C reason:
Radiation safety is another vital area in laboratories that work with radioactive materials. However, the maintenance logs for equipment would not typically be the main focus of radiation safety inspections. Instead, radiation safety inspections would concentrate on ensuring proper shielding, monitoring, and training are in place.
Choice D reason:
Electrical safety is also essential, but similar to chemical and radiation safety, it is not the primary focus when inspecting equipment maintenance logs. Electrical safety would involve checking for proper wiring, grounding, and protection against electrical hazards.
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