Help with: Clearance | Prospective | Actual | Iteration | Weights | BSA | Albumin Corrections | Iron-dextran Dosing
Creatinine Clearance
To calculate creatinine clearance, you must enter age, height, weight, and gender in the Patient Parameters section and serum creatinine in Creatinine Clearance section. You can use the Birthdate field to auto calculate the age.
Adjusted weight is used if actual weight is greater than 120% of ideal body weight.
For patient age 65 years or older, the serum creatinine will be rounded to 1.0 if it is less than 1.0.
If you want to use your own clearance value (such as when calculated clearance is greater than 120 mL/min, you can enter a value in User-defined Cl and this value will be used for calculations. The Calculation Cl displays the clearance that will be used for calculations.
Note: Cockroft-Gault equation is used to estimate clearance. For Jelliffe estimation, see Rx Calculator.
Prospective Calculations
Always complete the Patient Parameters and Clearance sections for vancomycin and aminoglycoside calculations. The Dosing Regimen is a common section for prospective and actual calculations (and iteration calculations for vancomycin).
For prospective calculation, Dose, Dosing Interval, Infusion Time, and Vd factor are required in the Dosing Regimen section. The results are displayed in the Prospective Calculation section after the Vd factor is entered or changed.
Note that some fields, such as dose, dosing interval, etc., are filled with default values in Dosing Regimen section. These can be changed to reflect your patient's values.
Actual Calculations
Always complete the Patient Parameters and Clearance sections for vancomycin and aminoglycoside calculations. The Dosing Regimen is a common section for prospective and actual calculations (and iteration calculations for vancomycin).
For actual calculation, all fields in Dosing Regimen section need to be filled or modified to reflect your patient's values. The results are displayed in the Actual Calculation section after the actual peak and trough are entered or changed.
Once you enter the peak and trough and true ke and Vd are calculated, you can search for an optimal dose in the Dose Optimization sub-section in Actual Calculation section.
Note that some fields, such as dose, dosing interval, etc., are filled with default values in Dosing Regimen section. These can be changed to reflect your patient's values.
Iteration Calculations for Vancomycin
Always complete the Patient Parameters and Clearance sections for vancomycin calculations. The Dosing Regimen is a common section for prospective, actual, and iteration calculations.
In cases where the vancomycin peak is not obtained, the trough can be used to calculate an iterated (theoretical) peak. Ensure that the patient's current regimen is correct in Dosing Regimen section. Enter the trough in Iteration Calculation section. An iterated peak will be calculated.
Once the ke and iterated peak are calculated, you can search for an optimal dose in the Dose Optimization sub-section in Iteration Calculation section.
Weight Calculations
The ideal weight is calculated using the formula 50 + 2.3×(inches over 60) for men and 45 + 2.3×(inches over 60) for women. The adjusted weight is calculated only if actual weight is greater than 120% ideal body weight using the formula: adjusted = ideal + 0.4×(actual - ideal). Of the three weights (actual, ideal, or adjusted), the Calc weight displays the weight that will be used for calculating clearance.
Note: For vancomycin, the actual weight is always used for Vd calculation.
Body-surface Area
To calculate body-surface area, enter height and weight. Make sure the correct units for height and weight are selected.
Albumin Correction
Phenytoin (Dilantin) and calcium need to be corrected for low albumin. Calcium needs correction for albumin < 4 and phenytoin for albumin < 4.5.
Iron Dextran
Enter height and weight and select gender to determine lean body weight (LBW). LBW is used to calculate the dose unless the patient's actual weight is less than LBW. Enter patient's current hemoglobin and target hemoglobin (usually > 14). The weight that will be used for calculations will be displayed as the Dosing weight.