The Maintenance Need for Water in Parenteral Fluid Therapy

In the category of genitourinary and fluid and electrolyte disorders, no paper bridges the discoveries of the 1930s through the 1950s and the practice of today as does the classic paper of Holliday and Segar.1 Today house officers and staff physicians use this same simple method for estimating insensible and urinary water losses of a child or adult of any size or age. Current textbooks and the latest editions of commonly used house officer manuals use this method of determining maintenance water needs based on calorie expenditure.2-5 This method involves a simple formula that relates the average calorie expenditure of a child to his/her weight in kg.The formula is 100 kcal/kg for an infant 3 to 10 kg; 1000 kcal plus 50 kcal/kg for a child from 10 to 20 kg; 1500 kcal plus 20 kcal/kg over 20 for weights >20 kg. On average, ∼40 mL/100 kcals/24 h will replace insensible losses and ∼60 mL/100 kcals/24 h will replace urinary losses. Conveniently, 100 mL/100 kcal/24 h of water meets average maintenance needs. Simple adjustments are made for recognizable exceptions.Drs Holliday and Segar were students and colleagues of several major figures of the fluid and electrolyte field: James L. Gamble, Daniel C. Darrow, Robert E. Cooke, William M. Wallace, and Allen M. Butler. These pediatric clinician scholars defined the nature of fluid and electrolyte balance in adults and children. Gamble and Darrow, in particular, developed the physiologic basis for fluid therapy at that time.Mac Holliday and Bill Segar were young faculty members at the University of Indiana when they developed a formula that defined maintenance needs for water in parenteral fluid therapy.1The formula was based on information from metabolic studies already published on factors relating metabolic rate, body water, and water loss to body weight—some of these were authored by Mac or Bill during their fellowship days in Boston and New Haven.An important feature of this paper is the comparison of estimated water requirements during growth as determined by four different systems: 1) the formula they developed; 2) body surface area—Butler; 3) basal and “activity” calories developed from tables—Darrow; and 4) age and calories (using a series of formulas)—Wallace. Agreement was close regardless of which system was used. Their formula was much simpler and practical, but precise. Bill Wallace, a reviewer of the paper for the journal and author of the “age and calorie” formula, remarked in a letter to Mac on how many aspects of water needs were uncovered that had not been precisely examined previously. Wallace went on to note: “I think people have been confused by attempting to make something very precise which does not need to be so. Like weighing a truck on an analytical balance” (personal communication, Malcolm A. Holliday, MD, 1997.)With the development of both total parenteral nutrition therapy and oral rehydration of diarrhea (administered under field conditions),78 this formula for estimating maintenance needs for water is still appropriate. Recent studies of water needs have confirmed its validity.9 Although simple, it is based on sound biologic and physiologic principles.