What Routine Intravenous Maintenance Fluids Should Be Used?

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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

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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 (ADH) on urine intracellular volume.30 Cell membranes 21 insensible (skin, respiratory tract) and flow rate. When ADH is present, the are permeable to water but not electro- http://adc.bmj.com/ sensible (urine and stool) water losses. renal solute load is effectively excreted lytes. As sodium is the major extracel- in a smaller urine volume producing lular cation (and hence osmole), it concentrated urine. Under these con- regulates the movement of water across Insensible water loss ditions urine output is often less than cells along an osmotic concentration This was generously estimated at half the values observed in healthy gradient, thus explaining cellular swel- 930 ml/m2/day (27 ml/kg/day).18 Recent children (approximately 25 ml/kg/ ling in the presence of hyponatraemia. data suggest the true figure may be only day).22 An increase in ADH is common It is also important to recognise the

half of this, with basal insensible losses on September 24, 2021 by guest. Protected copyright. role of potassium in the regulation of from the skin being 250 ml/m2/day during many childhood diseases, in tonicity balance. Potassium is a major (7 ml/kg/day) and via the respiratory response to stress (pain, fever, surgery) intracellular osmole, and may directly tract 170 ml/m2/day (5 ml/kg/day).19 or secondary to use of opiates and non- 23–25 influence extracellular sodium concen- Additionally many other risk factors steroidal anti-inflammatory drugs. tration by altering the distribution of may reduce insensible water loss such Under these conditions the administra- water between fluid compartments.25 as use of humidifiers in ventilated tion of free water frequently leads to Potassium loss, both urinary and stool, patients (80% reduction in respiratory hyponatraemia because the kidneys are 5626 may be significant in disease; yet its water loss) or a thermo neutral environ- unable to excrete the water load. direct influence on serum sodium con- ment.17 Bluemle et al have shown Interestingly, the type of fluid adminis- centration is often not considered.25 28 insensible water losses of as little as tered may influence ADH levels. Judd et 330 ml/m2/day (10 ml/kg/day) in cata- al showed that 0.9% saline but not 5% bolic acute renal failure patients.20 dextrose reduced ADH concentrations Tonicity of intravenous fluids postoperatively.21 It is crucial that clinicians appreciate the *Crawford calculated caloric expenditure Thus the total fluid loss (sensible plus difference between osmolarity and toni- based on the calories utilised per surface area insensible) during acutely illness or city. The osmolarity of a solution is the of the body. The calculated caloric expenditure following surgery may amount to number of osmoles of solute per litre of at each body surface area increment can be converted to weight by cross-referencing sur- approximately half that suggested by solution. The tonicity of a solution refers face area to weight using standard growth Holliday and Segar (50–60 ml/kg/day).56 to the total concentration of solutes that charts. The ratio of weight to surface area Also, the often overlooked production of exert an osmotic force across a mem- rapidly declines from birth to 10 kg. The endogenous water from tissue catabo- Holliday and Segar method does not take this brane in vivo. For example, 5% dextrose into account. lism (water of oxidation) may be has the same osmolarity as plasma (286 20 increased in acute disease. In healthy mosm/l H2O) but is rapidly metabolised **From the data of Talbot. children, this has been estimated to be in blood to water. Thus its in vivo tonicity

www.archdischild.com DEBATE 413 Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from Table 2 Approximate sodium concentration, in vitro osmolarity, in vivo tonicity, historical assumptions concerning and theoretical volume of electrolyte free water (EFW) provided by commonly sodium handling are based on salt used intravenous solutions depleted subjects. Indeed massive sodium loads from large volume resus- In vitro citation of infants and children with Sodium* osmolarityÀ In vivo tonicity` Volume of EFW1 sepsis (80–180 ml/kg/day) using 0.9% Intravenous solution (mmol/l) (mOsm/l H2O) (mOsm/l H2O) per litre infused saline did not produce hypernatrae- 5% dextrose 0 286 0 1000 mia.35 Additionally an epidemic of 0.18% saline in 4% 30 300 60 824 hypernatraemia has not been documen- dextrose 0.45% saline 75 150 154 500 ted in hospitalised adults where isotonic 0.45% saline in 5% 75 432 150 500 maintenance fluids are routine. When dextrose present, the aetiology of hypernatraemia 0.9% saline 154 308 308 0 in this scenario is frequently due to well 0.9% saline in 5% dextrose 154 586 308 0 recognised factors such diabetis insipi- 36 *The apparent discrepancy between the in vitro sodium concentration (0.9% saline ) of 154 mmol/l and dus or over-use of loop diuretics. the in vivo plasma sodium of 144 mmol/l is due to the phenomenon of pseudohyponatraemia. In The debate as to the optimal isotonic human plasma, approximately 7% of the plasma volume is occupied by albumin and lipid, falsely fluid is ongoing. For example, lowering the true sodium concentration plasma by 10 mmol/l (7% of 155). ÀIn vitro osmolarity refers to the number of osmoles of solute per litre of solution. Hartman’s solution has a more physio- `In vivo tonicity refers to the total concentration of solutes which exert an osmotic force across a logical concentration of chloride than membrane in vivo (excludes the osmotic effect of dextrose because it is rapidly metabolised in blood). 0.9% saline and hence does not cause 1Calculated on the basis that electrolyte free water distributes to the intracellular and extracellular space hyperchloraemia. The benefit of in a ratio of 2:1. Hartman’s solution versus 0.9% saline is not currently known. It is important is equal to that of electrolyte free water, complications of acute hyponatraemia to stress that dextrose may be added to as it contains no salt or other active include encephalopathy with seizures, these isotonic solutions (commonly in osmole (zero tonicity). Every litre of 5% irreversible brain damage, or brain concentration of 5–10%), when clini- dextrose infused results in the expan- death from cerebral herniation.5–10 cally indicated to avoid hypoglycaemia sion of the intracellular and extracellu- Children are also among the most without changing the solution’s in vivo lar fluid space by one litre (two thirds of susceptible to hyponatraemic brain tonicity (table 2). Recent evidence sug- this distributes to the intracellular space injury.56Fatal hyponatraemia can occur gests that a 1% dextrose solution follow- and one third to the extracellular space). within hours of hypotonic fluid admin- ing uncomplicated paediatric surgery Similarly, for every litre of 0.18% saline istration, particularly if standard fluid may be adequate.37 A suitable solution in 4% dextrose water infused, only 1/5th maintenance rates are used (100–120 for neonates and infants is 0.9% saline (200 ml) is isotonic to plasma (table 2). ml/kg/day).10 in 5% dextrose water, which is commer- The remaining 800 ml is electrolyte free cially available. We advocate 0.9% saline (with or without added dextrose) as a water, which will expand the intracel- THE RATIONALE FOR ISOTONIC lular fluid compartment. This is parti- safe maintenance solution, both peri- MAINTENANCE FLUID cularly relevant if excretion of water is operatively and in the acute phase of The paramount consideration in the http://adc.bmj.com/ limited by ADH.5–7212831This fluid shift most childhood illnesses requiring hos- choice of intravenous fluid is the may even occur in the absence of hypo- pitalisation (for example, pneumonia, requirement to maintain serum sodium natraemia.32 Small increases in tissue bronchiolitis, and meningitis). Here, the at a normal level. The use of isotonic water retaining effect of antidiuretic water through the use of hypotonic solutions such as 0.9% saline is more hormone may necessitate a moderate fluids may be harmful in conditions appropriate in acutely sick children as degree of fluid restriction (50–60%) to such as cerebral oedema where minor they do not theoretically expand the prevent fluid overload. The concept of increases in cerebral water may lead to intracellular fluid space. Isotonic solu-

fluid maintenance should not be con- on September 24, 2021 by guest. Protected copyright. disproportionately large increases in tions preserve intracellular function and fused with replacement therapy where intracranial pressure. integrity, by minimising changes in abnormal or excessive quantities of plasma sodium concentration and toni- water and electrolytes may be lost. In The incidence and neurological city. this instance the biochemical composi- complications of acute Use of 0.9% saline as maintenance tion and tonicity of the replacement hyponatraemia fluid, if combined with appropriate fluid solution should approximate that which Hyponatraemia is a common biochem- restriction, will result in a two to is lost. ical finding in hospitalised children and threefold increase in daily sodium is most commonly due to excess water intake compared to the traditional intake rather than salt loss.6 7 22 23 Shann regime. However, the concern that this CONCLUSION and Germer showed an incidence of may cause severe hypernatraemia is We have shown a number of pitfalls in hyponatraemia (Na ,134 mmol/l) as without foundation because the sodium the Holliday and Segar approach to high as 45% in hospitalised children concentration and tonicity of 0.9% parenteral therapy, namely that it with pneumonia and 50% in bacterial saline is similar to plasma. Andersen et focuses on fluid and electrolyte require- meningitis.8 Hanna et al recently al showed a rise in plasma sodium only ments for healthy children. In acute reported a 30% incidence of admission after intravenous administration of disease or following surgery, caloric hyponatraemia in infants with bronch- hypertonic 3% saline but not 0.9% expenditure, insensible water losses, iolitis requiring intensive care admission saline, despite a temporary positive and urine output are frequently much in the United Kingdom, 13% of which sodium balance.33 Heer et al showed less than in health (often 50–60% of the had seizures.9 Halberthal et al was able chronic sodium loading in volunteers reference values). Furthermore, this to show a direct link between hypona- does not produce an increase in plasma approach fails to recognise the impor- traemia and the use of hypotonic main- sodium, body water, or weight as tance of tonicity with its central role in tenance fluid.7 The neurological previously suggested.34 Many of the the distribution of water between fluid

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compartments (intracellular and extra- 5 Arieff AI, Ayus JC, Fraser CL. Hyponatraemia and 23 Sharples PM, Seckl JR, Human D, et al. Plasma Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from death or permanent brain damage in healthy and cerebrospinal fluid arginine vasopressin cellular space). children. BMJ 1992;304:1218–22. inpatients with and without fever. Arch Dis Child We therefore agree with Moritz and 6 Arieff AI. Postoperative hyponatraemic 1992;67:998–1002. Ayus who advocate isotonic solutions encephalopathy following elective surgery in 24 Dudley HF, Boling EA, Le Quesne LP, et al. children. Paediatr Anaesthes 1998;8:1–4. Studies on antidiuresis in surgery: effects of such as 0.9% saline for routine fluid 7 Halberthal M, Halperin ML, Bohn D. Acute anaesthesia, surgery and posterior pituitary 38 maintenance in children. Hypotonic hyponatraemia in children admitted to hospital: antidiuretic hormone on water metabolism in solutions, such as 0.18% or even 0.45% retrospective analysis of factors contributing to its man. Ann Surg 1954;140:354–65. 25 Halperin ML, Bohn D. Clinical approach to saline, are potentially dangerous when development and resolution. BMJ 2001;322:780–2. disorders of salt and water balance. Emphasis on renal water excretion is limited by ADH. 8 Shann F, Germer S. Hyponatraemia associated integrative physiology. Crit Care Med This raises a significant ethical barrier to with pneumonia or bacterial meningitis. Arch Dis 2002;18:249–72. 26 Al-Dahhan J, Jannoun L, Haycock GB. Effect of conducting a randomised control study Child 1985;60:963–6. 9 Hanna S, Tibby SM, Durward A, et al. Incidence salt supplementation of newborn premature as most acutely ill or postoperative of hyponatraemia and hyponatraemic seizures in infants on neurodevelopmental outcome at 10–13 patients have increased ADH levels. severe respiratory syncytial virus bronchiolitis. years of age. Arch Dis Child 2002;87:F234. 27 Steele A, Gowrishankar M, Abrahamson S, et al. There are few occasions in medicine Acta Paediatr 2003;92:430–4. 10 Playfor S. Fatal iatrogenic hyponatraemia. Arch Postoperative hyponatremia despite near-isotonic where mortality could be reduced by a Dis Child 2003;88:646. saline infusion: a phenomenon of desalination. task as simple as changing from a 11 Talbot FB. Basal metabolism standards for Ann Intern Med 1997;126:1005–6. 28 Aronson D, Dragu RE, Nakhoul F, et al. hypotonic maintenance solution to an children. Am J Dis Child 1938;55:455–9. 12 Pickering DE, Winters RW. Fluid and electrolyte Hyponatremia as a complication of cardiac isotonic one. management in children. Pediatr Clin North Am catheterization: a prospective study. Am J Kidney 1954:873–899. Dis 2002;40:940–6. 29 Leaf A. Regulation of intracellular fluid volume 13 Illner K, Brinkmann G, Heller M, et al. and disease. Am J Med 1970;49:291–5. ACKNOWLEDGEMENTS Metabolically active components of fat free mass 30 Edelman IS, Leibman J, O’Meara MP, et al. and resting energy expenditure in nonobese We would like to thank Dr Shane Tibby for Interrelations between serum sodium adults. Am J Physiol Endocrinol Metab his assistance in preparation of this manu- concentration, serum osmolarity and total 2000;278:E308–15. script. exchangeable sodium, total exchangeable 14 Briassoulis G, Venkataraman S, Thompson A. potassium and total body water. J Clin Invest Energy expenditure in critically ill children. Crit Arch Dis Child 2004;89:411–414. 1958;37:1236–72. Care Med 2000;28:1166–72. doi: 10.1136/adc.2003.045302 31 Hannon RJ, Boston VE. Hyponatraemia and 15 Verhoeven JJ, Hazelot JA, van der Voort E, et al. intracellular water in sepsis: an experimental Comparison of measured and predicted energy ...... comparison of the effect of fluid replacement with expenditure in mechanically ventilated children. either 0.9% saline or 5% dextrose. J Pediatr Surg Authors’ affiliations Crit Care Med 1998;24:464–8. 1990;4:422–5. D Taylor, A Durward, Paediatric Intensive 16 Coss-Bu JA, Klish WJ, Walding D, et al. Energy 32 Duke T, Molyneux EM. Intravenous fluids for metabolism, nitrogen balance, and substrate Care Unit, Guy’s Hospital, London, UK seriously ill children: time to reconsider. Lancet utilisation in critically ill children. Am J Clin Nutr 2003;362:1320–1. 2001;74:664–9. 33 Andersen LJ, Norsk P, Johansen LB, et al. Correspondence to: Dr A Durward, Paediatric 17 Sosulski R, Polin RA, Baumgart S. Respiratory Osmoregulatory control of renal sodium excretion Intensive Care Unit, 9th floor, Guy’s Tower water loss and heat balance in intubated infants after sodium loading in humans. Am J Physiol Block, Guy’s Hospital, St Thomas Street, London receiving humidified air. J Pediatr 1998;275:R1833–42. 1983;103:307–10. SE1 9RT, UK; [email protected] 34 Heer M, Baisch F, Kropp J, et al. High dietary 18 Heeley AM, Talbot NB. Insensible water losses sodium chloride consumption may not induce per day by hospitalised infants and children. body fluid retention in humans. Am J Physiol Am J Dis Child 1955;90:251–5. 2000;278:F585–97. REFERENCES 19 Lamke LO, Nilson Ge, Reithner L. Insensible 35 Skellett S, Mayer A, Durward A, et al. Chasing perspiration from the skin under standard

the base deficit: hyperchloraemic acidosis http://adc.bmj.com/ 1 Darrow DC, Pratt EL. Fluid therapy; relation to environmental conditions. Scan J Clin Lab following 0.9% saline fluid resuscitation. Arch Dis tissue composition and expenditure of water and 1977;37:325–31. Child 2000;83:514–16. electrolyte. JAMA 1950;143:365–73. 20 Bluemle LW, Potter HP, Elkington JR. Changes in 36 Daggett P, Deanfield J, Moss F, et al. Severe 2 Talbot NB, Crawford MD, Butler AM. body composition in acute renal failure. J Clin hypernatraemia in adults. BMJ 1979;5:1177–80. Homeostatic limits to safe fluid therapy. Invest 1956;10:1094–108. 37 Berleur MP, Dahan A, Murat I. Perioperative N Engl J Med 1953;248:1100–8. 21 Judd BA, Haycock GB, Dalton N, et al. infusions in paediatric patients: rationale for using 3 Gamble JL, Butler AM. Measurement of renal Hyponatraemia in premature babies and Ringer-lactate solution with low dextrose water requirement. Am Physicians following surgery in older children. Acta Paediatr concentration. J Clin Pharm Ther 1944;58:157–61. Scand 1987;76:385–93. 2003;28:31–40. 4 Holliday MA, Segar WE. The maintenance need 22 Harned HS, Cooke RE. Symptomatic 38 Moritz ML, Ayus JC. Prevention of hospital- on September 24, 2021 by guest. Protected copyright. for water in parenteral fluid therapy. Pediatrics hyponatraemia in infants undergoing surgery. acquired hyponatremia: a case for using isotonic 1957;19:823–32. Surg Gynecol Obstet 1957;104:543–50. saline. Pediatrics 2003;111:424–5.

Maintenance fluid therapy hormone secretion (SIADH), it may be ...... more accurate to refer to non-osmotic ADH production, since haemodynamic baroreceptor stimuli, such as hypovo- Rubbing salt in the wound laemia, may be physiologically appropriate despite the adverse effect on M Hatherill sodium.167 The reported morbidity and mortality ...... associated with hospital acquired hyponatraemia have given momentum to The case against isotonic parenteral maintenance solution calls for increasing the tonicity of PMS.1–38–11 Implicit in such proposals n a recent review, Moritz and Ayus tion of antidiuretic hormone (ADH) are the assumptions that hyponatraemia have suggested that isotonic parent- associated with conditions such as results from a net sodium deficit, Ieral maintenance solution (PMS) bronchiolitis (33%), pneumonia (31% exacerbated by hypotonic PMS, and that should be used to prevent hospital and 45%), bacterial meningitis (50%), this sodium deficit may be avoided by acquired hyponatraemia in children.1 and postoperative pain or nausea.2–7 using an isotonic solution.1–38–11 Hospital acquired hyponatraemia may Although it has been termed a syn- Therefore, if we contemplate a change be exacerbated by non-osmotic produc- drome of inappropriate antidiuretic in practice, we must consider whether

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Theoretical effects of variation in the volume of PMS Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from

Both examples apply to a 10 kg child with non-osmotic ADH production, TBW = 6 l, estimated isotonic (Na + K = 154 mmol/l) urine output of 1 ml/kg/h, estimated IWL of 35 ml/kg/day, and initial sodium = 140 mmol/l.

Example 1 100 ml/kg/day hypotonic solution (0.2% sodium chloride equivalent, Na + K = 34 mmol/l).1

Water Sodium/potassium Input 100 ml/kg = 1 l Input (Na+K) = 34 mmol Urine output 25 ml/kg/day = 0.25 l Urine output (Na+K) = 39 mmol IWL output 35 ml/kg/day = 0.35 l Water balance = +0.4 l (Na+K) balance = 25 mmol New Na = [(Na 6 TBW) + balance (Na+K)]/[TBW + water balance]19 New Na = [(140 6 6) –5]/[6 + 0.4] = 130 mmol/l

Example 2 60 ml/kg/day hypotonic solution (0.2% sodium chloride equivalent, Na + K = 34 mmol/l)

Water Sodium/potassium Input 60 ml/kg = 0.6 l Input (Na+K) = 20 mmol Urine output 25 ml/kg/day = 0.25 l Urine output (Na+K) = 39 mmol IWL output 35 ml/kg/day = 0.35 l Water balance = 0 l (Na+K) balance = 219 mmol New Na = [(140 6 6) –19]/[6 + 0] = 137 mmol/l

hyponatraemia is indeed caused by a N In the absence of randomised con- endogenous water of oxidation (270 ml/ deficit of sodium, or by an excess of trolled trials, there is insufficient m2/day) is subtracted, net IWL would water, and whether the logical response evidence to support the safety, effec- amount to 30–35 ml/kg/day.25 Appro- should be a change to the electrolyte tiveness, or relative merit of isotonic ximately one third of IWL occurs via the content, or the prescribed volume of PMS in children. respiratory tract, and two thirds via PMS. insensible evaporation from the skin.29 This article will examine the flaws in Since cutaneous IWL is determined by http://adc.bmj.com/ the argument for increasing the tonicity PRINCIPLES OF MAINTENANCE body surface area, net IWL varies with of PMS, and explore an alternative FLUID THERAPY age, and may be as little as 520 ml/day hypothesis: that reducing maintenance In order to avoid hyponatraemia (or in adults under basal conditions.30 fluid volume would be equally or more hypernatraemia) a tonicity balance In 1956 Holliday and Segar devised a effective as a prophylactic measure must be preserved, by matching input method for calculating maintenance against hyponatraemia. Although pre- and output of both water and electro- fluid requirements, in which both insen- vious authors have suggested a reduc- lytes to maintain an isotonic final sible and urinary water losses were tion in the amount of prescribed product.18 Each input and output may based on energy expenditure.14 Main- on September 24, 2021 by guest. Protected copyright. maintenance fluid, it should be empha- be divided into two components, the tenance electrolyte needs of 3 mmol/kg/ sised that the merits of either proposal volume of water, and the content of day sodium and 2 mmol/kg/day potas- have yet to be tested in large prospective effective osmols (sodium and potassium were somewhat arbitrarily based clinical trials.41213 sium), so that the net effect on tonicity on the amount delivered by human The case against a change to iso- may be calculated from the sum of these breast milk feeds (1 mmol/kg/day tonic PMS as a prophylactic measure separate components.18 sodium and 2 mmol/kg/day potas- against hospital acquired hyponatrae- A nephro-centric approach to main- sium).13 14 mia in children hinges on four key tenance fluid therapy that ignores IWL Caloric expenditure was estimated as issues: will contain an inherent error, since all 100 kcal/kg/day for an infant weighing inputs and all outputs need to be con- up to 10 kg, so that water loss could be N Traditional volume recommendations sidered.18 19 Although such an approach calculated per kg body weight.14 Using for PMS are greater than actual might be acceptable in adults, children this approach, IWL for a 10 kg infant requirements in children at risk of would be calculated as 50 ml/kg/day, 13 14 have greater proportional surface area, non-osmotic ADH production. and the magnitude of error would with 16 ml/kg/day subtracted for endo- N Electrolyte-free insensible water loss increase with the proportion of IWL.20 genous water of oxidation, equating to (IWL) should be included in the It is important to note that IWL, the net insensible loss of 34 ml/kg/day.14 calculation of a tonicity balance in ‘‘perspiratio insensibilis’’ of Santorio, Urinary losses, based on the water 15 children. represents loss of electrolyte-free water.21 required to excrete the solute load of N The principal mechanism leading to Estimated IWL may be derived from cows’ milk, would be calculated as 66 hyponatraemia is the primary anti- data reported in hospitalised infants and ml/kg/day, or 2.75 ml/kg/h.14 diuresis (dilution), not the secondary smaller children, ranging from 29 to 54 The sum of the net IWL (34 ml/kg) natriuresis (desalination).16 17 ml/kg/day for a 10 kg infant.22–28 After and renal water loss (66 ml/kg) produced

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the arithmetically pleasing calculation normalised serum sodium in hypona- volume of electrolyte-free water admi- Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from of 100 ml/kg/day.31 Moritz and Ayus traemic patients, it did not lead to a nistered, the sodium falls even if iso- assert that this formula for calculating significant outcome advantage or dis- tonic fluid is administered to produce a water needs ‘‘clearly has passed the test advantage, except in post hoc sub- net positive sodium balance, evidence of of time’’.1 However, even though almost analyses.38 Duke et al compared oral the primary dilutional nature of the half a century has passed, the formula fluid restriction and full intravenous hyponatraemia.44 48 49 Therefore, if the has not been put to the test. maintenance, with no statistically sig- fundamental problem is antidiuresis, nificant difference in serum sodium or rather than natriuresis, surely the prin- 37 PROBLEMS WITH TRADITIONAL adverse outcome. ciple of treatment should be less fluid, MAINTENANCE Clearly, hypovolaemia and inadequate not more salt? RECOMMENDATIONS organ perfusion may be disadvanta- 39 Urine output may be 1 ml/kg/h, or less, geous to patients with meningitis. THEORETICAL EFFECTS OF if determined by non-osmotic ADH However, neither the volume nor VARIATION IN MAINTENANCE production rather than solute load, and composition of maintenance fluid FLUID REGIMEN therefore children at risk of hyponatrae- should be a consideration in the treat- It has been suggested that a tonicity mia may receive 40–50 ml/kg/day over ment of hypovolaemia, which should balance should be used to predict and above their actual maintenance be corrected immediately with rapid changes in natraemia, rather than an 40 water needs.3 It is also notable that infusion of resuscitation fluid. It has electrolyte-free water approach.18 hospital acquired hyponatraemia may even been suggested that synthetic Changes in sodium are related to the be associated not only with hypotonic colloid, rather than saline, should be ratio between effective osmols (sodium PMS, but with amounts of fluid that used to avoid sodium loading during and potassium) and total body water, 41 exceed, by up to 50%, even cur- resuscitation. and the term ‘‘isotonic’’ refers to a rently recommended maintenance solution in which the sum of both volumes.23103233 MECHANISMS OF sodium and potassium amounts to 154 14750 Individual maintenance water needs HYPONATRAEMIA mmol/l. Changes in sodium may also depend on motor activity, tempera- ADH increases the permeability of the then be predicted by calculating a ture, and biological work.23 34 Since the distal renal tubule and collecting duct, tonicity balance from the net gain or 18 19 energy expenditure of physically immo- resulting in renal conservation of water loss of effective osmols and water. bile, critically ill children may be and inappropriately high urinary Five per cent dextrose is considered less than 40 kcal/kg/day, their mainte- sodium concentration, so that children necessary for maintenance of normogly- 34 nance water requirement would be who develop hyponatraemia may caemia and cerebral metabolism. reduced.34 35 We might expect a further excrete urine isotonic to plasma.64243 However, although the additional dex- 30% reduction of IWL in patients Excessive ADH production has also been trose increases the osmolality of PMS, breathing warmed humidified air termed a phenomenon of salt loss or we would not expect it to affect serum through a ventilator circuit, which ‘‘desalination’’, based on the secondary sodium, since glucose is not an effective 118 illustrates an important aspect of fluid increase in net urinary sodium loss, osmol. balance in critically ill ventilated chil- possibly due to suppression of aldoster- From the examples in the box, it is dren.29 If their fluid requirement is one, increased natriuretic peptide, or apparent that giving 100 ml/kg/day of dramatically reduced, by virtue of lower increased glomerular filtration, which hypotonic (0.2% saline equivalent) PMS http://adc.bmj.com/ respiratory and cutaneous IWL, and the occurs after over-expansion of the intra- to a child with non-osmotic ADH sodium requirement is unchanged, the vascular space.6161742–45 production might result in a clinically concentration of PMS required to deliver Experimental models show that the significant fall in sodium from 140 29 34 35 that sodium increases. However, acute hyponatraemia is primarily dilu- mmol/l to 130 mmol/l. It can be seen this consideration does not apply to the tional, while the secondary natriuresis from the large positive fluid balance, vast majority of hospitalised children contributes to the maintenance of and small negative sodium balance, that with non-osmotic ADH production, ongoing hyponatraemia.16 17 In a model this fall would be primarily dilutional. If on September 24, 2021 by guest. Protected copyright. whose reduction in fluid loss is pre- of 1-desamino-D-arginine vasopressin tonicity were increased from 0.2% to dominantly urinary (high electrolyte (DDAVP) infusion, two thirds of the 0.9% saline equivalent, with volume content), rather than insensible (zero acute hyponatraemia was ascribed to unchanged at 100 ml/kg/day, hypona- 136293435 electrolyte content). water retention, and one third to sodi- traemia might be prevented at the um depletion.16 In a similar experiment, expense of a large positive fluid balance. REDUCTION IN MAINTENANCE rats infused with DDAVP (but not argi- If instead of increasing sodium con- FLUID VOLUME nine vasopressin) maintained constant tent, the amount of hypotonic PMS Previous authors have suggested a sodium balance, and hyponatraemia (0.2% saline equivalent) were decreased reduction of maintenance fluid volume resulted from water retention alone.45 to 60 ml/kg/day, we might expect a in high risk patients, and fluid allow- It is important to note that the clinically insignificant fall in sodium to ance of 50 ml/kg/day is standard prac- secondary ‘‘desalination’’ may be pre- 137 mmol/l over a period of 24 hours, tice for infants with bronchiolitis in vented by fluid restriction.17 In normal but with no increase in total body water. some centres.241213 The rationale for adults given pitressin, there was no This minor fall in sodium may not even avoiding such ‘‘fluid restriction’’ is that increase in natriuresis if fluid intake occur if fluid restriction effectively 17 it may be disadvantageous to children were restricted to prevent over-expan- reduces the natriuresis. with hypovolaemia.12 36 Three prospec- sion of the intravascular space.17 It tive studies address this issue in menin- follows that the administration of iso- LACK OF EVIDENCE FOR gitis.73738 Powell et al showed that tonic saline may be futile unless fluid ISOTONIC PARENTERAL plasma vasopressin fell with the admin- volume is also reduced, since ongoing MAINTENANCE SOLUTIONS istration of additional fluid, suggesting natriuresis may negate the effect of this Changes in sodium may be predicted by an appropriate ADH response to hypo- intervention.15 46 47 theoretical manipulation of tonicity bal- volaemia.7 Singhi et al showed that Studies in surgical patients show that ance, but it should be emphasised that although (hypotonic) fluid restriction while the fall in sodium is related to the current recommendations for water and

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electrolyte needs have not been rigor- energy expenditure, water loss, and 17 Leaf A, Bartter FC, Santos RF, et al. Evidence in Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from man that urinary electrolyte loss induced by ously tested, and are based on estimated electrolyte needs in hospitalised chil- pitressin is a function of water retention. J Clin values for energy expenditure and IWL dren. Traditional recommendations for Invest 1953;32:868–78. derived from small historical stu- maintenance fluid volume exceed 18 Carlotti APCP, Bohn D, Mallie JP, et al. Tonicity dies.11424–26 Although individual needs actual requirements and contribute to balance, and not electrolyte-free water calculations, more accurately guides therapy for vary, recommendations for administra- the development of hyponatraemia in acute changes in natremia. Intensive Care Med tion of PMS should be appropriate for children at risk of non-osmotic ADH 2001;27:921–4. the majority of all hospitalised children, production. Reducing the volume of 19 Mallie JP, Ait-Djaffer Z, Laroche F, et al. Variations in plasma sodium concentration in while simultaneously safeguarding maintenance fluid may be a more post-operative patients depend on an electrolyte- against hypo- or hypernatraemia in high effective prophylactic measure than free water balance, part of a tonicity balance. risk conditions.113143451 an increase in sodium content, and a Clin Nephrol 1998;49:287–92. prospective clinical trial should be 20 Wallace WM. Quantitative requirements of the If we consider increasing the tonicity infant and child for water and electrolytes under of PMS to prevent hyponatraemia, performed to resolve this issue. varying conditions. Am J Clin Pathol several fundamental questions are yet Unless the evidence of such a trial 1953;23:1133–41. to be answered.1 Would isotonic PMS be were to support the use of isotonic 21 Santorio S. In: De Statica Medicina 1614. 41 51 22 Ginandes GJ, Topper A. Insensible perspiration safe? Crucially, does it work? Is maintenance fluid in children, an in children. Statistical correlation of insensible isotonic PMS actually effective in redu- injudicious change in clinical practice perspiration and various body measurements; cing the incidence of hyponatraemia? may not correct the errors of the past proposed basal standards for children. Am J Dis Child 1936;52:1335–47. Would reducing the maintenance 50 years, but compound them. 23 Darrow DC, Pratt EL. Fluid therapy. Relation to volume of hypotonic PMS be equally Arch Dis Child 2004;89:414–418. tissue composition and the expenditure of water 412 and electrolyte. JAMA 1950;143:365–73, effective? Given that hyponatraemia doi: 10.1136/adc.2003.045047 may occur despite isotonic fluid admin- 432–9. 24 Levine SZ, Wheatley MA. Respiratory metabolism istration, and despite a positive sodium Correspondence to: Dr M Hatherill, Paediatric in infancy and childhood. The daily heat balance, isotonic PMS may not be Intensive Care Unit, Institute of Child Health, production of infants—predictions based on the Red Cross Children’s Hospital, Klipfontein insensible loss of weight compared with direct effective in preventing hyponatraemia, Road, Cape Town, 7700, South Africa; 44 47 measurements. Am J Dis Child unless fluid volume is also reduced. [email protected] 1936;51:1300–23. A large multicentre randomised trial is 25 Talbot NB, Crawford JD, Butler AM. Homeostatic needed to compare the current standard limits to safe parenteral fluid therapy. N Engl J Med REFERENCES 1953;248:1100–8. of care (hypotonic PMS) with (a) iso- 26 Heeley AM, Talbot NB. Insensible water losses tonic PMS, (b) isotonic PMS at reduced 1 Moritz ML, Ayus JC. Prevention of hospital- acquired hyponatraemia: a case for using isotonic per day by hospitalised infants and children. volume, and (c) hypotonic PMS at saline. Pediatrics 2003;111:227–30. Am J Dis Child 1955;90:251–5. reduced volume, in children at risk of 2 Hanna S, Tibby SM, Durward A, et al. Incidence 27 Newburgh LH, Johnston MW. The insensible loss of water. Physiol Rev 1942;22:1–18. hyponatraemia. A recent review consid- of hyponatraemia and hyponatraemic seizures in severe respiratory syncitial virus bronchiolitis. 28 Newburgh LH, Wiley FH, Lashmet FH. A method ers the ethical aspects of such a trial, in Acta Paediatr 2003;92:430–4. for the determination of heat production over long which equipoise must be maintained.52 3 Halberthal M, Halperin ML, Bohn D. Acute periods of time. J Clin Invest 1931;10:703–21. Clearly, it would be unethical to perform hyponatraemia in children admitted to hospital: 29 Sosulski R, Polin RA, Baumgart S. Respiratory retrospective analysis of factors contributing to its water loss and heat balance in intubated infants a study in which the balance of evidence development and resolution. BMJ receiving humidified air. J Pediatr suggests that one treatment arm is 2001;322:780–2. 1983;103:307–10. 4 Shann F, Germer S. Hyponatraemia associated 30 Lamke LO, Nilsson GE, Reithner HL. Insensible

inferior to the other. It would be equally http://adc.bmj.com/ with pneumonia or bacterial meningitis. Arch Dis perspiration from the skin under standardized unethical to perform a study in which Child 1985;60:963–6. environmental conditions. Scand J Clin Lab Invest lack of scientific rigour jeopardises the 5 Dhawan A, Narang A, Singhi S. Hyponatraemia 1977;37:325–31. validity of the findings.52 and the inappropriate ADH syndrome in 31 Chesney RW. The maintenance need for water in parenteral fluid therapy. Pediatrics The morbidity and mortality asso- pneumonia. Ann Trop Paediatr 1992;12:455–62. 6 The osmoreceptor-antidiuretic hormone feedback 1998;102:399–400. ciated with hypotonic PMS is not control system. In: Guyton AC, ed. Textbook of 32 Mor J, Ben-Galim E, Abrahamov A. disputed, but also underlines the pitfalls medical physiology, 8th edn. Philadelphia: WB Inappropriate antidiuretic hormone secretion in of adopting a standard of care without Saunders 1991:314–16. an infant with severe pneumonia. Am J Dis Child 7 Powell KR, Sugarman LI, Eskanazi AE, et al. 1975;129:133–5.

1–38–11 14 52 on September 24, 2021 by guest. Protected copyright. robust evaluation. For the rea- Normalization of plasma arginine vasopressin 33 Bhalla P, Eaton FE, Coulter JBS, et al. sons outlined above, we may not concentrations when children with meningitis are Hyponatraemic seizures and excessive intake of assume that isotonic PMS would be given maintenance plus replacement fluid hypotonic fluids in young children. BMJ therapy. J Pediatr 1990;117:515–22. 1999;319:1554–7. superior to the current regimen, nor that 8 Playfor S. Fatal iatrogenic hyponatraemia. Arch 34 Shafiee MAS, Bohn D, Hoorn EJ, et al. How to isotonic PMS is without potential dis- Dis Child 2003;88:646–7. select optimal maintenance intravenous fluid advantages.41 51 A prospective trial to 9 Durward A, Tibby SM, Murdoch IA. therapy. Q J Med 2003;96:601–10. Hyponatraemia can be caused by standard fluid 35 Taylor RM, Cheeseman P, Preedy V, et al. Can compare the effect of different main- regimens. BMJ 2000;320:943. energy expenditure be predicted in critically ill tenance fluid regimens on sodium and 10 Arieff AI, Ayus JC, Fraser CL. Hyponatraemia children? Pediatr Crit Care Med 2003;4:176–80. fluid balance would be both feasible, and death or permanent brain damage in healthy 36 Moritz ML. Re: Water balance: is more always and ethically acceptable, if serial mea- children. BMJ 1992;304:1218–22. better? Response to post-publication peer review. 11 Bohn D. Children are another group at risk of Pediatrics 28 April 2003. surement of sodium and effective data hyponatraemia perioperatively. BMJ 37 Duke T, Mokela D, Frank D, et al. Management of safety monitoring could be ensured. 1999;319:1269. meningitis in children with oral fluid restriction or Therefore, until it can be shown that 12 Duke T. Fluid management of bacterial meningitis intravenous fluid restriction at maintenance in developing countries. Arch Dis Child volumes: a randomised trial. Ann Trop Paediatr isotonic maintenance fluid is both safe, 1998;79:181–5. 2002;22:145–57. and effective, in preventing hospital 13 Holliday MA, Segar WE. Reducing errors in fluid 38 Singhi SC, Singhi PD, Srinivas B, et al. Fluid acquired hyponatraemia, calls for wide- therapy management. Pediatrics restriction does not improve the outcome of acute 2003;111:424–5. meningitis. Pediatr Infect Dis J spread change in practice are prema- 14 Holliday MA, Segar WE. The maintenance need 1995;14:495–503. 189 ture. for water in parenteral fluid therapy. Pediatrics 39 Tureen JH, Tauber MG, Sande MA. Effect of 1957;19:823–32. hydration status on cerebral blood flow and 15 Adrogue HJ, Madias NE. Hyponatremia. cerebrospinal fluid lactic acidosis in rabbits with SUMMARY N Engl J Med 2000;342:1581–9. experimental meningitis. J Clin Invest The morbidity and mortality associated 16 Verbalis JG. Pathogenesis of hyponatremia in an 1992;89:947–53. experimental model of the syndrome of 40 Carcillo JA, Davis AL, Zaritsky A. Role of early with hospital acquired hyponatraemia inappropriate antidiuresis. Am J Physiol fluid resuscitation in pediatric septic shock. JAMA should prompt re-evaluation of measured 1994;267:R1617–25. 1991;266:1242–5.

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41 Gosling P. Salt of the earth or a drop in the saline infusion: a phenomenon of desalination. 49 Aronson D, Dragu RE, Nakhoul F, et al. Arch Dis Child: first published as 10.1136/adc.2003.045047 on 21 April 2004. Downloaded from ocean? A pathophysiological approach to fluid Ann Intern Med 1997;126:20–5. Hyponatremia as a complication of cardiac resuscitation. Emerg Med J 2003;20:306–15. 45 Gross PA, Anderson RJ. Effects of DDAVP and catheterization: a prospective study. Am J Kidney 42 Schwartz WB, Bennett W, Curelop S, et al. A AVP on sodium and water balance in the Dis 2002;40:940–6. syndrome of renal sodium loss and conscious rat. Am J Physiol 1982;243:R512–19. 50 Edelman IS, Leibman J, O’Meara MP, et al. hyponatraemia probably resulting from 46 Adrogue HJ, Madias NE. Aiding fluid Interrelations between serum sodium inappropriate secretion of antidiuretic hormone. prescription for the dysnatremias. Intensive Care concentration, serum osmolarity and total Am J Med 1957;23:529–42. Med 1997;23:309–16. exchangeable sodium, total exchangeable 43 Louis PH, Fortenberry JD. Syndrome of 47 Rose BD. New approach to disturbances in the potassium and total body water. J Clin Invest inappropriate secretion of antidiuretic hormone. plasma sodium concentration. Am J Med 1958;37:1236–56. In: Oski FA, ed. Principles and practice of 1986;81:1033–40. 51 Abu-Ekteish F, Zahraa J. Hypernatraemic pediatrics, 2nd edn. Philadelphia: JB Lippincott 48 Guy AJ, Michaels JA, Flear CTG. Changes in the dehydration and acute gastro-enteritis in children. Company, 1994:1099–101. plasma sodium concentration after minor, Ann Trop Paediatr 2002;22:245–9. 52 Duke T, Molyneux EM. Intravenous fluids for 44 Steele A, Gowrishankar M, Abrahamson S, et al. moderate and major surgery. Br J Surg seriously ill children: time to reconsider. Lancet Postoperative hyponatremia despite near-isotonic 1987;74:1027–30. 2003;362:1320–3.

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hen I did resident on-call, content and advertisement. Look at the for example, ‘‘Why are the people in this every now and then a colleague lifestyle articles telling our teens what photograph smiling?’’ Yes, it might be Wwould discover me in front of they should be buying and where, how because they’re happy, but it might also children’s TV on a Saturday or Sunday they should look and feel, what they be because they’re being paid to smile, morning, usually consuming a hurried should do and when. Actually, it is on and that this helps you interpret the on-call breakfast. The excuse ‘‘It was on this last issue that I find the single essential falseness of the photograph. when I came in’’ wore a bit thin, but redeeming feature of some of these Extend this to why the people in the fortunately now I have another, much magazines. The problem pages often photograph are thin, or holding cigar- better one should I need it. I’m doing offer such sensible, down to earth, ettes, and you can see the power. market research. It is the same thing useful advice that I’m left wondering It is easy to get carried away with this, that a previous boss would claim he was whether the agony aunts and uncles but it is also very easy to fall into an doing when he read the local news- inhabit a different planet to the rest of advertising trap ourselves. If it weren’t, paper—a rag of doubtful value and the content providers. if we were completely media savvy, then variable accuracy. ‘‘This is part of my How is this excuse for how I spend why would the otherwise extremely job’’ he’d say, and believe. ‘‘This is our the occasional 20 minutes on a Saturday sensible and money conscious pharma- constituency—a fact we forget at our morning at all relevant to being a ceutical companies take us out to peril. This is what the people who pay paediatrician? Well, it must be part of dinner? I don’t think I was a particularly our wages think. Or what they are being our role as child advocates to see that stupid child, but when I was 10 and saw told to think.’’ young people at least have a fighting an aunt smoking John Player Special Back to the weekend morning, and if chance of interpreting this deluge of cigarettes, I did think that they must http://adc.bmj.com/ you haven’t tried this recently, you information in a sensible manner. Our have been a great brand if they were should. Watch television as an anthro- response could be to bring up our named after a formula one racing car. It pologist. Count the adverts and examine children in isolation—in a hut in the took me a few years to figure out the their strange internal logic. Look at the Scottish Highlands or Australian many falsehoods in that assumption. link between the adverts and the pro- Outback. We could deny them access You wouldn’t take a child outside on gramme content. Find out what our to television, magazines, and no un- a rainy day without making sure they children are being told to think. I’m told vetted book written since, say, 1950. were wearing a coat, would you? Why, on September 24, 2021 by guest. Protected copyright. that the best way to advertise to Then we could release them into the then, would we allow a child out into a children is to pitch the message just world at 18 and see how they got on, world populated with anorexic models, beyond their level of understanding. My secure in the knowledge that at the very cigarettes, guns, fallible rock stars, soft guess is that this somehow appeals to least they’d had a wholesome child- drinks, and fast food, without compar- both their and their parents’ sense of hood. able defences? The mental environment premature ability, or it confuses the The other alternative, if we accept has become very complex, and our child while appealing to the parent, or that the world that we live in is riddled children need some sort of protection maybe it just confuses both. I do know with the media and, by association, in order to be able to survive. Now, that after about 20 minutes of watching advertising, then we could try to teach you’ll excuse me please, as my favourite I’m at least 10 IQ points the poorer. them a little bit about what we’re begin- cartoon is about to start … The next thing to do is to pick up a ning to understand about how advertis- teen magazine. As I’ve said, it is market ing works. Media literacy sounds like a I D Wacogne research, so you have a perfect excuse. wishy-washy concept, but it is a power- Ian Wacogne is a consultant in general Look at the seamless segue between ful idea. Discussing with a 10 year old, paediatrics at Birmingham Children’s Hospital