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.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
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.
Correct Answer is B
Explanation
Choice A reason:
The order of citrate, heparin, EDTA, and fluoride is not the correct sequence for blood collection. The correct order is essential to prevent cross-contamination of additives between tubes, which could interfere with test results. Citrate tubes should be drawn first to ensure that the blood does not clot prematurely, but heparin should not follow immediately after citrate.
Choice B reason:
Citrate tubes, which contain sodium citrate, are used for coagulation tests and must be drawn first to ensure the proper blood-to-additive ratio. EDTA tubes are drawn next because EDTA binds calcium and prevents clotting, making it ideal for complete blood counts and other hematology studies. Heparin tubes, which prevent clotting by inhibiting thrombin and thromboplastin, are drawn after EDTA. Lastly, fluoride tubes, which contain a glycolysis inhibitor, are drawn to preserve glucose levels and are typically used for glucose and lactate testing.
Choice C reason:
Starting with fluoride is not recommended as it could lead to contamination of the EDTA and heparin tubes with fluoride, which could affect the results of certain tests, such as calcium determinations in heparin tubes. The order of draw is designed to minimize such risks.
Choice D reason:
This sequence is incorrect because fluoride tubes are not drawn before EDTA and heparin tubes. The presence of fluoride could potentially contaminate the subsequent tubes and alter the results of the tests that require heparin or EDTA as an anticoagulant.
In phlebotomy, following the correct order of draw is crucial. The order is established based on the type of additive in each tube and its potential to interfere with tests conducted in subsequent tubes. The standard order is: blood cultures, citrate tubes, serum tubes with or without clot activator and gel, heparin tubes with or without gel, EDTA tubes, and lastly, fluoride tubes. This sequence helps prevent cross-contamination and ensures the accuracy of laboratory results, which are critical for patient diagnosis and treatment.
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