Which of the following blood collection systems uses interchangeable multi-sample tubes that allow a phlebotomist to draw several blood specimens at the same time?
Evacuated tube system
Hypodermic needle and syringe system
Winged infusion set and syringe system
Lancet micro collection system
The Correct Answer is A
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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Choice A Reason:
Signing a release for laboratory results is a form of expressed consent, not implied consent. Expressed consent is given explicitly, either orally or in writing, and is clearly and unmistakably communicated. It involves a clear action of agreement to the specific procedure or intervention proposed.
Choice B Reason:
Signing a document of agreement for a research study is also an example of expressed consent. The patient is actively agreeing to participate in the study, which is a direct and informed action. This type of consent is necessary for research studies to ensure that participants are fully aware of the study's nature and any potential risks involved.
Choice C Reason:
Implied consent occurs when a patient's actions suggest consent without verbal or written confirmation. Offering an arm to a phlebotomist is a non-verbal communication that implies the patient is willing to have their blood drawn. This is a common practice in medical settings where the action of presenting an arm indicates readiness for the procedure.
Choice D Reason:
A family member nodding for a phlebotomist to proceed does not constitute the patient's implied consent. Consent must come directly from the patient unless they are unable to provide it, in which case a legal surrogate may give consent on their behalf. The nod of a family member cannot be assumed as the patient's consent.
Correct Answer is D
Explanation
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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