What Routine Intravenous Maintenance Fluids Should Be Used?

DEBATE 411 Maintenance fluid therapy were concerns about profound neonatal Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from ....................................................................................... hyponatraemia causing neurological problems in infants as the result of either excessive or the wrong kind of What routine intravenous maintenance fluid given to mothers during labour.2 It is therefore timely to revisit this fluids should be used? problem. Two experts have been asked to give their views to encourage further N P Mann debate (see accompanying articles34). Do write to ADC with your comments ................................................................................... about how paediatric practice in this area can be improved. An introduction to the debate Arch Dis Child 2004;89:411 ntravenous maintenance fluid is of miscalculation of infusion rates and widely used in general paediatric also the potential for mistakes in terms Correspondence to: Dr N P Mann; Npmann2@ aol.com Ipractice and more children who come of dosing errors with additives. It has into hospital receive intravenous fluid been widely recognised in recent years REFERENCES than in the past. The intravenous route that there is a high incidence of hypona- 1 Moritz ML, Ayus JC. Prevention of hospital- is frequently used because enteral main- traemia in children treated with intrave- acquired hyponatremia: a case for using isotonic tenance or rehydration treatment is nous maintenance fluids. Is this because saline. Pediatrics 2003;111:227–30. more labour intensive and uses valuable of excessive water or too little salt? 2 Spencer SA, Mann NP, Smith ML, et al. The effect of intravenous therapy during labour on maternal staff time; furthermore modern pumps Moritz and Ayus discussed the high and cord sodium levels. Br J Obstet Gynaecol for delivery of fluids are safe. frequency of hyponatraemia in these 1981;88:480–3. Nevertheless in developing countries children in their paper in Pediatrics in 3 Taylor D, Durward A. Pouring salt on troubled waters. The case for isotonic parenteral 1 the enteral route is still more widely February 2003. They suggested the use maintenance solution. Arch Dis Child used even for sick dehydrated children. of isotonic saline rather than use of 2004;89:411–4. Are there are any dangers of intrave- hypotonic fluids for maintenance 4 Hatherill M. Rubbing salt in the wound. The case against isotonic parenteral maintenance solution. nous fluids? Clearly there is a possibility therapy. More than 20 years ago there Arch Dis Child 2004;89:414–8. Maintenance fluid therapy (basal metabolic rate plus growth and ....................................................................................... activity) using this data in relation to body surface area (fig 1). Holliday and Segar further advanced this by indexing Pouring salt on troubled waters energy expenditure to body weight rather than surface area, assuming 1 ml of water loss was associated with D Taylor, A Durward http://adc.bmj.com/ the fixed consumption of 1 kilocalorie.4 ................................................................................... The typical fluid losses for children The case for isotonic parenteral maintenance solution (table 1) thus equate with an energy requirement of 120 kcal/kg/day for a 12 ntravenous fluid and electrolyte ther- and is recommended in current paedia- 10 kg child. apy for acutely ill children has been a tric and medical textbooks. There are two main flaws with this cornerstone of medical practice for Advances in our understanding of approach. First, it is now known that I on September 24, 2021 by guest. Protected copyright. well over 50 years. The scientific meth- water and electrolyte handling in health resting energy expenditure is closely odology behind fluid regimens gener- and disease have called into question related to fat free mass which includes ated much debate in the early 1950s the validity of the Holliday and Segar muscle and the four major metabolic following the pioneering work of approach. Specifically, many authors organs (heart, liver, kidneys, and Darrow, Talbot, Gamble and others have reported how hypotonic mainte- brain).13 Eighty per cent of the resting who recognised the important relation nance fluid may result in iatrogenic energy expenditure is accounted for by between caloric expenditure and hyponatraemia in hospitalised patients, these four organs which comprise only requirements for water.1–3 often with devastating consequences.5–10 7% of total body mass. As a result, the Caloric expenditure was originally In this article we re-evaluate each of use of weight alone to calculate energy calculated according to body surface the concepts on which this traditional expenditure may significantly overesti- area, which at the bedside required regime is based (energy expenditure, mate caloric requirements. On average, either tables or nomograms.1 In 1957 and water and electrolytes require- the weight based method overestimates Holliday and Segar simplified this ments) and use this to make the case energy requirements in infants by 14% approach, relating energy expenditure for an alternative, namely isotonic fluid. compared to the surface area method to one of three weight based categories (fig 1).4 Second, energy expenditure in (,10 kg, 10–20 kg, .20 kg).4 Elec- PITFALLS OF THE WEIGHT BASED healthy children, on whom historic trolyte requirements were also calcu- HOLLIDAY AND SEGAR models are based, is vastly different in lated on a weight basis, producing an APPROACH acute disease or following surgery. ‘‘ideal’’, hypotonic solution comprising Energy expenditure Using calorimetric methods, energy 0.2% saline in 5% dextrose water (0.18% Talbot originally estimated basal meta- expenditure in these patients is closer saline in 4% dextrose in the United bolic rate in children based on water to the basal metabolic rate proposed by Kingdom). This simple regime was loss.11 Crawford extended this concept, Talbot, averaging 50–60 kcal/kg/day.14–16 subsequently adopted on a global scale by presenting total energy requirements This overestimate is multifactorial: ill www.archdischild.com 412 DEBATE 15 ml/100 kcal burnt.4 Thus, all these Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from Table 1 Typical water losses per factors need consideration when asses- 100 kilocalories (kcal) of energy sing overall water balance. expended for a healthy 10 kg child Estimated water loss Electrolyte requirements (ml per 100 kcal/ Source of water loss day) In healthy breast fed infants Holliday and Segar computed a dietary sodium Insensible intake of 1 mEq/100 calories per day.4 Skin 30 Darrow recommended 3 mEq of sodium Respiratory 15 per 100 calories of energy expended per Sensible day.4 This is based on urinary excretion Stool 10 rates of sodium in healthy, milk fed Figure 1 Daily caloric expenditure according Minimal sweating 10 infants. However, daily electrolyte Urine 50 to the weight based method of Holliday and requirements in disease may differ con- Segar and by surface area method of Crawford, and basal metabolic rate. Total 115 siderably from this. For example, large Comparison of two different methods for urinary losses of sodium and potassium Data calculated according to Pickering and calculating caloric expenditure across weight 12 may occur through the phenomenon ranges (open squares = Holliday and Segar’s Winters. of desalination.27 28 Furthermore, Al- weight based method; open Dahhan et al showed a beneficial effect * circles = Crawford’s surface area method ; Urinary loss of water on neurodevelopmental outcome from referenced against basal metabolic rate**). According to Holliday and Segar, urin- doubling the daily sodium intake (4 to 5 ary water losses for healthy children mmol/kg) in neonates.26 This refutes the patients are catabolic, often relatively amount to 50–60 ml/kg/day4 based on assumption that the neonatal kidney is inactive, and, in the intensive care the work of Pickering and Winters incapable of ‘‘handling’’ a high sodium environment may be pharmacologically (table 1).12 The basis of this fluid regime load. The recent discovery of the most 14–17 sedated or muscle relaxed. Almost was the observation that 15/28 infants potent natriuretic hormones, urodilatin half of the caloric intake suggested by and 20/25 children (unspecified diag- and gut-related natriuretic peptide has Holliday and Segar is designated for noses) who were given intravenous also shed new light on sodium regula- growth, an unrealistic goal in acute dextrose produced urine with an tion. 16 disease. Although fever and sepsis per ‘‘acceptable’’ urine osmolarity between The rationale behind the traditional se may increase metabolic rate this is 4 150 and 600 mosm/l H2O. They pre- approach is to balance sodium intake to usually limited to less than 1.5 times the sumed patients with dilute urine match sodium loss. However, this fails basal metabolic rate, burns being an received too much water and conversely to appreciate the single most important exception. those with concentrated urine too little role of sodium in acute illness, namely water. maintenance of plasma tonicity.25 29 Water requirements Today we recognise this does not take There is a strong inverse relation bet- Historically water requirements have into account the overriding influence of ween plasma sodium concentration and been based on crude estimates of both antidiuretic hormone

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