Adult and Pediatric Dosages Based on Body Surface Area Chapter 14 Adult and Pediatric Dosages Based on Body Surface Area

General Information About Body Surface Area (BSA) Major factor in calculating medication dosages for both children and adults when body’s physiologic processes are more closely related to body surface than to weight

Calculating BSA Calculated in square meters (m2) using client’s weight and height Use calculator with square root capabilities

Medications Frequently Dosed According to BSA Antineoplastic agents Medications prescribed for clients with severe burns

BSA Formulas One formula uses kg and cm measurements BSA = square root of One formula uses lb and inch measurements

Calculating BSA from kg and cm: Example 1 Calculate BSA of client with weight of 104 kg and height of 191 cm Express BSA to nearest hundredths

Calculating BSA from kg and cm: Example 1 Square root of 5.517 = 2.35 m2

Calculating BSA from kg and cm: Example 2 Calculate BSA of client with weight of 59 kg and height of 157.5 cm Express BSA to nearest hundredths

Calculating BSA from kg and cm: Example 2 Square root of 2.585 = 1.61 m2

Calculating BSA from lb and in: Example 1 Calculate BSA of child with weight of 34 lb and height of 24 in Express BSA to nearest hundredths

Calculating BSA from lb and in: Example 1 Square root of 0.260 = 0.51 m2

Calculating BSA from lb and in: Example 2 Calculate BSA of adult with weight of 142.7 lb and height of 61.3 in Express BSA to nearest hundredths

Calculating BSA from lb and in: Example 2 Square root of 2.793 = 1.67 m2

Dosage Calculation Based on BSA Once BSA known, simple multiplication to calculate dosage

Calculating Dosage: Example 1 Dosage safe/recommended 5 mg per m2 Child BSA of 1.1 m2

Calculating Dosage: Example 2 Dosage safe/recommended 25 to 50 mg per m2 Child BSA of 0.76 m2 Lower dosage: Upper dosage:

Assessing Prescriptions Based on BSA Typically refer to drug literature to determine safe/recommended dosages for medications prescribed If drug label for medication available, safe/recommended dosage ranges printed on side label

Calculating Dosages Calculation steps same whether using medication labels or other drug literature

Before Beginning Read carefully Safe/Recommended dosage ranges may be based on total daily dose or individual dose

Daily Dosage Ranges If range based on daily dose, divide daily dose by number of doses client receives per day

Two-Step Calculation Process Client’s BSA placed into range formula to determine safe/recommended dosage Compare result to prescribed dosage to determine if prescribed dosage safe/recommended for this client