Satellite Symposium. Sponsored by

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1 Satellite Symposium Sponsored by

2 Management of fluids and electrolytes in the preterm infant in the first week of life Pam Cairns St Michaels Hospital Bristol

3 Healthy, term, breast fed babies Limited intake for the first few days Weight loss of up to 10% Contraction of the extracellular compartment Diuresis Natriuresis

4 Preterm infants

5 What is normal?? Extreme prematurity is a non physiological state At 26 weeks gestation a fetus should contain 80-90% water and be surrounded by fluid Post natal adaptation to a variable environment

6 What are the insensible Urinary output Respiratory tract Stool losses losses? Transepidermal water loss

7 Transepidermal water loss Degree of immaturity (TEWL = 140ml/kg at 24 weeks, and 12ml/kg/day at 32 weeks) Postnatal age Radiant heater Humidity of environment

8 Recommendations Place in plastic bag at birth, Nurse in double skinned incubator at 80% + humidity Use bubble bbl wrap when opening doors

9 Renal function Glomerular filtration rates increase rapidly after birth - dependant on post conceptual age Tubular immaturity - limited ability to either retain or excrete sodium - at risk of both hyper and hyponatraemia May excrete large volumes of dilute urine despite significant ifi dehydration d

10 Sick preterms with RDS Delayed diuresis / natriuresis/ weight loss - occurs just before respiratory improvement Mediated by atrial natriuretic peptide Diuretics ineffective Failure of early weight loss is associated with increased time on oxygen Still relevant in antenatal steroids and prophylactic surfactant era?

11 Restricted versus liberal water intake Cochrane review, Bell and Acarregui (2004) 4 RCTS ( ) Total 358 neonates Varying interventions and duration

12 Results - Patent ductus arteriosus Relative risk = 044(95%CI ) Number needed to treat = 5.3

13 Results - Necrotizing Enterocolitis Relative risk , (95% CI ) Number needed to treat

14 Results - Bronchopulmonary dysplasia Relative risk (95%CI 0.56,1.14) 14) All trials had a tendency towards All trials had a tendency towards reduction

15 Results- death Relative risk = 0.52 ( 95% CI ) Number needed to treat = 15.9 BUT!

16 Caveats Different population Fewer extreme prems Pre widespread antenatal steroid and surfactant use

17 Sodium No sodium loss though skin (inability to sweat under 36 weeks) Extracellular fluid is mainly water and sodium So - Sodium balance should also be negative within the first 2-3 days of life Sodium is needed for growth

18 Antidiuretic Hormone Activity it Present from early fetal life Triggered by increase in tonicity of extracellular fluid or central baroreceptors In prems central hypotension, or deceased central venous return may stimulate May result in hyponatremia

19 Early vs late sodium replacement Hartnoll et al Arch Dis Child 2001, Costarino et al J Pediatr 1992 Increased risk hypernatraemia Increased length of time in oxygen

20 Recommendations Minimize insensible losses Be cautious - easy to add, difficult to take away Individualize - any initial fluid prescription is an educated guess

21 Monitoring i Weigh 12 hourly (incubator scales) Measure urine volume (ml/kh/hr) Calculate fluid balance 8-12 hourly Measure urea and electrolytes 8-12 hourly Rising sodium is a sign of dehydration Falling sodium may be evidence of fluid overload or ADH secretion

22 Fluid prescribing Consider water and nutritional intake separately Remember glucose requirements will be variable Start at 60ml/kg/day and adjust as required Allow 3-5% weight loss/day Absence of weight loss is evidence of fluid Absence of weight loss is evidence of fluid overload

23 Electrolytes l t Sodium - do not add until serum sodium falling and weight loss has occurred Once natriuresis has started - commence maintenance of 4mmol/kg/day Start 1-2mmol/kg/day potassium from day 2 if falling

24 How long to restrict? t? Very variable practice between NICUs The majority of babies do not require prolonged restriction Beware of limiting nutrition

25 Conclusion Early weight loss is good Early sodium is bad Preterm babies bi are highly hl variable!