Question

Calculate the dosages as indicated. Use the labels where provided. Order: Infuse \(500 \mathrm{~mL}\) D5W with \(800 \mathrm{mg}\) theophylline at \(0.7 \mathrm{mg} / \mathrm{kg} / \mathrm{hr}\). The client weighs \(73.5 \mathrm{~kg}\). How many milligrams should this client receive per hour?

Short answer

51.45 mg of theophylline per hour.

Step-by-step solution

Understand the Problem

The task is to determine the amount of theophylline, in milligrams, to administer per hour based on the patient's weight and the ordered dosage.

Identify Given Values

We are given that the client's weight is 73.5 kg and the dosage is 0.7 mg/kg/hr.

Set Up the Calculation

To find the dosage in milligrams per hour, multiply the client's weight by the dosage rate per kilogram: \(0.7 \text{ mg/kg/hr} \times 73.5 \text{ kg}\).

Perform the Multiplication

Calculate \(0.7 \times 73.5 = 51.45\).

Interpret the Result

The client should receive 51.45 mg of theophylline per hour.

Key concepts

Theophylline Administration

Theophylline is a common bronchodilator used in the treatment of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). Administering theophylline involves careful calculation to ensure therapeutic and safe levels are maintained in the bloodstream.

The primary goal of theophylline administration is to open up air passages by relaxing muscles in the lungs and chest. However, due to its narrow therapeutic window, precise dosing is crucial. An under-dose may lead to ineffective symptom control, whereas an overdose could result in toxicity, manifesting as nausea, diarrhea, or even cardiac arrhythmias.

When preparing theophylline for infusion, healthcare providers must consider various factors, including the patient’s weight, the concentration of theophylline in the solution, and the ordered dosage rate. In hospital settings, the medication is often administered through an IV drip mixed in a solution such as D5W (5% dextrose in water). This ensures a steady and controlled administration that can be adjusted if necessary.

Medication Dosing

Medication dosing refers to the calculation of the correct amount of a drug to administer to a patient. This involves knowing the drug's concentration and the desired dose based on the patient’s specifics, like their weight or age.

There's often a required dosage rate, which specifies how much of the drug is needed per unit of measurement over time. In the case of theophylline, the standard rate is presented as `mg/kg/hr`—meaning milligrams of drug required per kilogram of body weight per hour.

Ensuring accurate dosing is vital to achieve the therapeutic effect without causing harm. Errors in dosing calculations can lead to either insufficient therapeutic effect or potential toxicity, hence healthcare providers need to be meticulous in performing these calculations:

• Start by confirming the prescribed dosage and the concentration of the medication available.
• Ensure all units match for accurate calculations, converting if necessary.
• Calculate dosage according to given rates and individualized patient parameters, such as body weight for weight-dependent medications like theophylline.

Patient Weight Calculation

Patient weight calculation is a fundamental component in determining the appropriate medication dosage for weight-dependent medications. Since many drugs are dosed based on the patient's body weight, an accurate measurement is critical.

When calculating doses, the weight should always be measured in kilograms (kg) because it is the standard unit used in medical dosing calculations. It helps standardize the practice globally, reducing errors in medication administration.

To properly perform dosage calculations:

• Start by accurately measuring the weight of the patient, usually with a properly calibrated scale.
• Record the weight in kilograms; if weighed in pounds, convert the figure to kilograms (1 kg = 2.20462 pounds).
• Use the weight in kilograms directly in your dosage calculation, multiplying it by the dosage unit per kilogram to find the correct amount to administer.
• Double-check the calculated dose to ensure it aligns with expected therapeutic doses and consult pharmacological guidelines if needed.

Accurate weight measurement and appropriate conversion significantly influence the safety and effectiveness of the treatment plan.