When using the evacuated tube method, which of the following will result in a failed venipuncture if the needle is at a 45° angle upon insertion?
The needle will collapse the vein.
The needle will go completely through the vein.
The needle will miss the vein superficially.
The needle will contact the upper wall of the vein.
The Correct Answer is B
Choice A reason:
Using a needle at a 45° angle does not typically result in collapsing the vein. A collapsed vein is more likely due to excessive vacuum pressure from the tube, a very small or fragile vein, or the tourniquet being too tight.
Choice B reason:
At a 45° angle, the needle is more likely to penetrate through the entire depth of the vein, especially if the vein is superficial. This can result in a failed venipuncture because the needle has entered and exited the vein, missing the opportunity to collect blood.
Choice C reason:
While a steep angle like 45° could cause the needle to miss the vein superficially, it is more likely that the needle would go through the vein at this angle rather than merely missing it superficially. A superficial miss is more likely with an angle that is too shallow.
Choice D reason:
Contacting the upper wall of the vein alone would not necessarily result in a failed venipuncture. However, at a 45° angle, the needle could easily slip through the vein entirely after contacting the upper wall, especially if the vein is not anchored well.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A Reason:
Explaining the procedure to both the parent and the child is crucial. It helps in preparing the child psychologically and ensures that the parent is informed and can provide support during the process. Clear communication can reduce anxiety and make the child more cooperative. It is also a part of informed consent, where the parent understands what the procedure entails and why it is necessary¹².
Choice B Reason:
Choosing not to tell the child when the needle insertion is coming might seem like a way to avoid causing them anticipatory anxiety. However, this approach can lead to mistrust. Children need to be prepared for what to expect, and surprising them can be more traumatic in the long run. It is better to be honest and use age-appropriate language to describe the sensation as a 'quick pinch' or 'poke'¹².
Choice C Reason:
Obtaining a heel stick is a common method for blood collection in infants, particularly newborns, as their veins are not as developed. However, for preschoolers, venipuncture is usually the preferred method because they have more developed veins, and it allows for a larger volume of blood to be collected if needed³.
Choice D Reason:
Obtaining a thumb stick is not a standard practice for blood collection in preschoolers. The thumb has bones and tendons close to the surface, which can increase the risk of injury. The preferred sites are the antecubital fossa of the arm or the back of the hand where the veins are more accessible and there is less risk of hitting bone³.
Correct Answer is C
Explanation
Choice A Reason:
Povidone-iodine is an antiseptic used for skin disinfection before and after surgery. It has a broad spectrum of antimicrobial activity, but it is not the preferred choice for capillary blood collection due to the potential interference with certain laboratory tests. Povidone-iodine needs to be completely dried to avoid hemolysis of the sample, which can affect test results.
Choice B Reason:
Hand sanitizer is generally used for hand hygiene and not for the disinfection of the site for blood specimen collection. While it is effective in killing germs on the skin, it contains emollients and gelling agents that can contaminate the blood sample and interfere with laboratory tests.
Choice C Reason:
70% isopropyl alcohol is the most commonly used disinfectant for aseptic technique in capillary blood collection. It is effective against a broad range of microorganisms and evaporates quickly, leaving no residue that could contaminate the sample. It is important to allow the alcohol to dry completely before performing the puncture to prevent stinging and sample dilution.
Choice D Reason:
A 10% chlorine bleach solution is not typically used for skin disinfection in blood collection due to its harshness and potential to cause skin irritation and damage. It is more commonly used for disinfecting surfaces and equipment in healthcare settings.
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