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BESPOKE FLUIDS
- John ML Boss, David J Campbell, Consultant Paediatric Anaesthetist (27 October 2006)
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Osmolarities of peri-operative fluid solutions in children
- Katharine L Thornton, Amber E. Young (13 October 2006)
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Peri-operative i.v. fluid determines incidence of hyponatraemia after paediatric spinal surgery
- Mark G. COULTHARD, Lyndsay S. CHEATER, and Debbie A. LONG (13 October 2006)
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Perioperative fluid therapy in children
- Isabeau A Walker, C. Way R. Dhamrait A. Way (27 September 2006)
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John ML Boss, PICU Fellow Royal Alexandra Hospital for Sick Children, David J Campbell, Consultant Paediatric Anaesthetist
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In response to letter posted by K Thornton and A Young titled - Osmolarities of peri-operative fluid solutions in children. Dear Editor - we agree with Drs Thornton and Young that near-isotonic fluids should be given in the peri-operative period, and that addition of glucose is necessary to prevent ketosis and a base excess with prolonged administration (post-operatively). We applaud and indorse their recommendation of Hartmann’s solution, with added glucoseas a post- operative fluid. We would point out that Hartmann’s solution does not contain bicarbonate, as stated in their table. The lactate in the Hartmann’s is subsequently metabolized in the liver to only 70% bicarbonate ions and to 30% glucose molecules(1). This amount of glucose, equivalent to only a 0.08% solution, would be insufficient to prevent ketosis. We would however question the tabulated osmolarity calculations for each solution. Since glucose has a molecular weight of 180, 180g of glucose is 1 mole. If added to 1 litre of water this would give an osmolarity of 1000 mosmol. 10g of glucose in a litre of water (a 1% solution) has an osmolarity of 55.6 mosmol/L. Application of this data would give osmolarities of 328, 403 and 528 mosmol/L for the Hartmann’s with 1%, 2.5% and 5% glucose solutions respectively. These figures are significantly lower than those stated in the table. However, Thornton and Young’s table does not present data on tonicity. We feel that this information should also be included to avoid confusion. The in vivo tonicity of each Hartmann’s solution would be 272, 264, and 250 mosmol/L for the 1%, 2.5% and 5% glucose additions respectively. Interestingly, the eventual tonicity of the infused fluid will be modified further by the metabolic fate of the lactate. Pain on infusion and peripheral vein phlebitis are partly determined by the osmolarity of a fluid, but also by its pH and composition(2). Our revised calculations add further weight to the argument that these Hartmann’s solutions with added glucose should be reasonably well tolerated. For comparison, the osmolarity of the commonly used(3) 0.45% Saline with 5% glucose is 432 mmol/L (although its tonicity is only 154 mmol/L). We have been in recent contact with Baxter Healthcare, who stated that sufficient demand for bespoke fluids would determine supply. Special fluid requests could be supplied if sufficient quantities were to be ordered together with appropriate evidence that the solution would be chemically stable. 1. White SA, Goldhill DR. Is Hartmann's the solution? Anaesth 1997; 52: 422-427. 2. Kuwahara T, Asanami S, Tamura T, Kubo. Dilution is effective in reducing infusion phlebitis in peripheral parenteral nutrition: an experimental study in rabbits Nutrition 1998; 14: 186-190. 3. Dearlove OR, Ram AD, Natsagdoy S, Humphery G. Hyponatraemia after post operative fluid management with half normal saline. Electronic Letter. Brit J of Anaesth 2006; 29 August. Conflict of Interest:None declared |
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Katharine L Thornton, Anaesthetist Department of anaesthesia, Frenchay Hospital, Amber E. Young
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Editor-Further to the very informative article on periperative fluid therapy in children by C.Way et al we would like to add some osmolarity calculations on various fluid combinations that we have established in order to give anaesthetists a more informed choice of the most appropriate isotonic fluid to give perioperatively. See fluid osmolarity chart here View Image
We strongly agree that isotonic fluids should be given in the perioperative period and that only 1% dextrose is required to prevent hypoglycaemia in perioperative children(1).
From our literature search it appears that any solution under 450 mosmol/litre gives a very low risk of thrombophlebitis(2) and on these grounds we would recommend that compound sodium lactate solution (Hartmann's), with an added 20mls of 50% dextrose to give a 1% dextrose solution (osmolarity of 352 mosmol/litre), is a suitable perioperative fluid in children. This solution is also very simple to make up in the absence of a commercial solution in the UK. Our practice is to restrict postoperative fluids to 70 - 80% of calculated maintenance using values recommended by Holliday and Segar(3).
References
1.Leelanukrom R et al. Paediatr Anaesth 2000;10:353-9
2.Arch.surg 1979;114:897-900
3.Holliday MA et al,J Paediatr 2004;145:584-7
Conflict of Interest:None declared |
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Mark G. COULTHARD, Paediatric Intensivist Royal Children's Hospital, Brisbane, AUSTRALIA, Lyndsay S. CHEATER, and Debbie A. LONG
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Editor- Cunliffe and Potter’s (1) editorial raises important questions about the prescription of intravenous fluids to the peri- operative paediatric population. The survey by Way et al. (2) confirms the lack of guidelines for fluid prescribing, and the potential risk of hyponatraemia in this group of patients. We would like to share the results of our recent work on this topic. The paediatric intensive care unit at the Royal Children’s Hospital in Brisbane, Australia admits 600 patients a year including approximately 30 children who undergo spinal instrumentation surgery. In 2003, a clinical pathway was introduced to standardise the care of post-operative paediatric patients undergoing spinal instrumentation. In July 2004 the standard IV fluid regimen was changed from 3.0% dextrose & 0.3% sodium chloride (Cohort 1) at two-thirds “maintenance” rate to 5% dextrose & Hartmann’s solution (Cohort 2) at full “maintenance” rate. The hourly full maintenance rate was defined as 4 mls/kg/hr for the first 10 kg; 2 ml/kg for the next 5 kg, and 1 ml/kg for each kilogram thereafter(3). All other aspects of the post-operative clinical care remained the same as per the clinical pathway. The administration of post-operative fluid boluses was at the discretion of the treating doctor. We conducted a retrospective study to compare the incidence of post- operative hyponatraemia in the two cohorts of children undergoing spinal instrumentation surgery who had received the two different IV fluid regimens. The two groups were equivalent for age, gender, underlying diagnosis, operative procedure and amount of bolus fluid received. The table shows the main results View Image . We conclude that the change in post-operative fluid regimen from 3% dextrose & 0.3% sodium chloride at two-thirds maintenance rate to 5% dextrose & Hartmann’s at full maintenance rate reduced the proportion of patients with post-operative hyponatraemia and the fall in serum sodium at 12–16 hours post-operatively. However, in our two year study there were no patients in either cohort with clinically significant hyponatraemia. We are not aware of good quality clinical trials to guide the management of paediatric peri-operative fluid therapy. We are currently enrolling patients in a randomised control trial to further investigate peri- operative fluid management in children. References 1. Cunliffe M, Potter F. Four and a fifth and all that. Br J Anaesth 2006; 97: 274-7 2. Way C, Dhamrait R, Wade A, Walker I. Perioperative fluid therapy in children: a survey of current prescribing practice. Br J Anaesth 2006; 97: 371-9 3. Holliday M, Segar W. The maintenance need for water in parenteral fluid therapy. Pediatrics 1957; 19: 823-32 Conflict of Interest:None declared |
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Isabeau A Walker Great Ormond Street Hospital NHS Trust, C. Way R. Dhamrait A. Way
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Editor - We thank Drs Coulthard, Cheater and Long for their interest in our paper and await the results of their randomised control trial with interest. We agree that a carefully conducted study is required, given that few anaesthetists currently prescribe isotonic fluids postoperatively for children. It is interesting from their retrospective results that the plasma sodium fell in both groups of children. This may reflect the fact that Hartmann’s is a hyponatraemic fluid (Na+ 131 mmol/l), or perhaps an indication of ‘desalination’ in the isotonic group as these patients appear to be receiving at least 30% more fluid that the hypotonic group (1). We agree with the choice of Hartmann’s rather than 0.9% saline as isotonic fluid for postoperative maintenance, although 5% dextrose Hartmann’s is not commercially available in the UK at present. Normal saline is far from ‘normal’ (chloride content of 154mmol/l) and has been associated with hyperchloraemic metabolic acidosis in children (2). This may be a benign condition, but the clinician’s response to a persisting acidosis (more fluid) may not be. We would feel unhappy with the suggestion to change to 5% dextrose 0.9% saline for routine postoperative maintenance. It is difficult to find one solution to fit all, but perhaps it is time to identify an ideal fluid for the ‘sick’ postoperative child, just as Holliday and Segar did in 1957 for ‘routine’ maintenance therapy. We would also like to stress that fluids used as volume replacement (as opposed to maintenance), should not contain dextrose. C. Way R. Dhamrait A. Wade I. Walker* London, UK * e-mail walkei@gosh.nhs.uk References: 1. Steele A, Gowrishankar M, Abrahamson S, Mazer D, Feldman RD, Halperin ML Postoperative hyponatraemia despite near-isotonic saline infusion. A phenomenon of desalination Ann Int Med 1997; 126: 20-25 2. Skellet S, Mayer A, Durwood A, Tibby SM, Murdoch IA. Chasing the base deficit: hyperchloraemic acidosis following 0.9% saline fluid resuscitation. Archives of Diseases in Childhood 2000; 83:514-516 Conflict of Interest:None declared |
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