A phlebotomist is preparing to draw blood from a patient for therapeutic drug monitoring. Which of the following questions should the phlebotomist ask?
"When was your last dose of lithium?"
"For how long have you been fasting?"
"When did you have your last alcoholic beverage?"
"Have you finished drinking the glucose solution?"
The Correct Answer is A
Choice A Reason:
Asking "When was your last dose of lithium?" is crucial for therapeutic drug monitoring (TDM). TDM is used to tailor dosages and maintain therapeutic levels in a patient’s bloodstream, especially for drugs with narrow therapeutic indices like lithium. The timing of the last dose can significantly affect blood levels, and knowing this information helps in interpreting the results accurately.
Choice B Reason:
While knowing the fasting status of a patient may be relevant for certain tests, it is not typically critical for TDM unless the medication being monitored is affected by food intake. Lithium levels are not significantly influenced by fasting, so this question is less relevant than knowing the timing of the last dose.
Choice C Reason:
Inquiring about the last alcoholic beverage is important if alcohol could interfere with the medication's metabolism or the test's accuracy. However, for lithium TDM, alcohol consumption is not as directly relevant as the timing of the last dose. Alcohol does not typically alter lithium levels unless it affects the patient's hydration status.
Choice D Reason:
Asking if the patient has finished drinking the glucose solution would be pertinent if conducting a glucose tolerance test. However, this is not relevant for TDM of lithium, as the glucose solution does not interfere with lithium levels or the TDM process.
In conclusion, for therapeutic drug monitoring, particularly for lithium, the most critical question is regarding the timing of the last dose. This information is essential to ensure that the blood levels reflect the peak or trough concentration, depending on what is being measured, and to avoid misinterpretation that could lead to inappropriate dosing adjustments.
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.
Choice B Reason:
Similarly, signing a document of agreement for a research study is another example of expressed consent. The patient is actively agreeing to participate in the study, which is a direct and informed action.
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.
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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