Problem 27 - Calculate With Confidence

Question

Calculate the following dosages using the medication label or information provided. Label answers correctly: tabs, caps, mL. Answers expressed in milliliters should be rounded to the nearest tenth where indicated. Order: Vistaril \(100 \mathrm{mg}\) IM stat. Available: Vistaril \(50 \mathrm{mg}\) per \(\mathrm{mL}\) ________

Step-by-Step Solution

Answer

2 mL

Step 1: Identify the Required Dosage

The doctor's order is for Vistaril at a dosage of 100 mg to be given immediately via intramuscular (IM) injection.

Step 2: Identify the Available Concentration

You have Vistaril available in a concentration of 50 mg per mL. This means each milliliter of the solution contains 50 mg of the medication.

Step 3: Calculate the Required Volume

To find out how many milliliters are needed, use the relationship \( \text{Volume} = \frac{\text{Ordered dosage}}{\text{Concentration per mL}} \). Substitute the values into the formula: \( \text{Volume} = \frac{100 \, \text{mg}}{50 \, \text{mg/mL}} = 2 \, \text{mL} \).

Step 4: Rounding and Final Answer

Since the calculated volume is exactly 2 mL, no rounding is necessary. Therefore, 2 mL of the medication is required for administration.

Key Concepts

Vistaril Dosage

Determining the correct dosage of Vistaril, a medication commonly used for its antihistamine and sedative effects, is crucial for patient safety. When a healthcare provider orders Vistaril, like in the case where 100 mg is prescribed, it is essential to ensure the ordered dose matches the therapeutic requirements for the patient. Most medications, including Vistaril, come with standard dosage guidelines, but adjustments might be necessary based on individual patient needs or specific conditions. It is important for healthcare professionals to double-check the prescribed dosage against the patient's medical history and possible contraindications to avoid adverse drug reactions.

Intramuscular Injection

Intramuscular injection (IM) is a common route for administering drugs like Vistaril. This method involves injecting the medication directly into the muscle tissue, which allows for rapid absorption due to the rich blood supply found in muscles. Intramuscular injections are preferred for medications that are either too irritating to veins or need to be absorbed faster than what subcutaneous injections offer. Using the correct technique is vital:

• Choose the appropriate injection site, such as the deltoid or gluteal muscles, to ensure absorption and minimize patient discomfort.
• Ensure the needle length is appropriate for the patient's muscle mass.
• Use sterile techniques to avoid infections.

Patients should be informed about the procedure to reduce anxiety and increase cooperation.

Medication Concentration

Understanding medication concentration is key to administering the correct dose. Concentration is often expressed in terms of the amount of drug per unit volume, such as 50 mg/mL for Vistaril. This means that in every milliliter of this solution, there are 50 mg of the active ingredient. Grasping this concept is essential, especially when preparing doses from solutions of different concentrations. When you know the concentration, you can calculate how much of the solution you need to deliver the required dose. Always double-check the medication label to confirm the concentration before drawing the medication.

Volume Calculation

Volume calculation is a fundamental step in ensuring the correct dose is given, especially when medications come in liquid form. For the Vistaril example, the calculation utilizes the formula:\[ \text{Volume} = \frac{\text{Ordered dosage}}{\text{Concentration per mL}} \]Here, the ordered dosage is 100 mg, and the concentration is 50 mg/mL, leading to a calculated volume of 2 mL. Performing these calculations accurately is critical because incorrect volumes can lead to underdosing or overdosing, both of which can have serious medical repercussions. Review and verify calculations to maintain patient safety.

Dosage Rounding

Although rounding might seem minor, in medical settings, it can make a significant impact. Dosage rounding involves adjusting the calculated volume to ensure it is appropriate for administration, typically rounding to the nearest tenth. In our example, no rounding was necessary because the volume was precisely 2 mL. However, in situations where rounding is required, it must adhere to best practices to avoid altering the medication's efficacy. When rounding is needed, always consider:

• The type of medication and its therapeutic index.
• Any potential impact on the patient's health.
• The standard rounding rules you’ve been taught or that are specified by your healthcare facility.

Practicing careful dosage rounding helps to ensure that the prescribed treatment remains effective and safe.