BODY SURFACE AS A BASIS FOR DOSAGE
GILBERT B. FORBES M.D.1
1 Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York
MODERN therapeutic technology, with its array of drugs, sera and infusates, has demanded that the pediatrician devise some means whereby these materials can be given in proper dosage to subjects of widely varying size. At the same time modern clinical investigation has indicated the extent to which the human young differ metabolically and physiologically from adults. The practitioner has seen for himself that the dosage of many therapeutic agents is far from a simple linear function of body weight. The result has been the formulation of a number of dosage schemes, the most recent of which is the surface-area rule. In this scheme, dosage is expressed as grams or milliliters of a given material per square meter surface area rather than per unit body weight.
Body surface is calculated from weight and height according to the conventional DuBois nomogram, or from weight alone. The use of this rule automatically provides the infant with a larger per kilogram dose than the older child. This is because surface area increases less rapidly than weight as the body grows.
