Dr. Nai Shun Tsoi Department of Paediatric and Adolescent Medicine Queen Mary Hospital Hong Kong SAR

Dr. Nai Shun Tsoi Department of Paediatric and Adolescent Medicine Queen Mary Hospital Hong Kong SAR

A very important aspect in paediatric intensive care and deserve more attention Basic principle is to maintain an adequate intravascular volume to provide a good cardiac output for better organ perfusion Avoid excessive fluid overload intravascular as well as extravascular compartment

In septic shock, rapid and vigorous fluid resuscitation in the initial phase is important for survival Patient can have significant hypovolaemia despite clinical feature of puffiness If hypovolemia not well managed, can progress to irreversible renal failure for which renal replacement therapy might be needed Impaired renal function is commonly encountered in hypotensive patient Fluid overload or pulmonary congestion can occur without much fluid given

Issues related to Halliday and Segar estimation of fluid requirement. Pediatrics 1957 Recommend daily requirement First 10kg: 100ml/kg 19-20kg: 50ml/kg 20kg and up: 20ml/kg Over-estimation of fluid requirement in critically ill cases Less water loss especially for ventilator cases, very good humidification Decrease energy -> less water production Autonomic dysfunction -> less insensible water loss SIADH -> less urine loss

Problem with fluid overload Intravascular compartment Hypertension, heart failure, pulmonary congestion Respiratory failure, increase ventilator support Difficult weaning Extravascular compartment Tissue oedema organ perfusion Worse if present of ascitis, risk of abdominal compartment syndrome -> iimpaired renal perfusion

Causes of fluid overload Too much fluid given Volume of drugs Humidification from mechanical ventilation Decrease urine output Renal failure Inappropriate ADH production Third space loss such as severe sepsis

Excessive fluid loss Renal tubular dysfunction Endocrine condition eg. cortisol deficiency Oral secretion in cases unable to swallow CSF and other drains GI loss (diarrhoea and vomiting) Complications > impair perfusion > pre-renal followed by renal failure

Formula for fluid supplement Humidified gas x0.75 Neuromuscular blockers x 0.7 Hyperpyrexia 10-12% per oc Radiant warmer? X 1.5 Phototherapy x 1.5 SIADH x 0.7 Hypothermia -12% per oc core temp less than 37oC Renal failure 0.3 + urine output Room temperature over 31oC +30% per oc Hyperventilation x 1.2 Burn Need frequent fluid evaluation for ICU cases Excessive loss >30ml/kg/day -> consider fluid replacement

Electrolytes contents of body fluid Source Na K Cl HCO3 Saliva 10 26 10 30 Gastric 60 10 130 0 Duodenum 140 5 80 0 Pancreas 140 5 75 115 Bile 145 5 100 35 Ileum 140 4 104 30 Colon 60 30 40 0 CSF 138 3 120 Average concentration in mmol/l

Electrolytes Composition of Parenteral Fluids Solutions Na + K + Ca 2+ Cl - Lactate mosm/l 0.9% NaCl 154 154 308 0.45% NaCl 77 77 154 D5/0.45% NaCl 77 77 406 3% NaCl 513 513 1026 5% Albumin 130-160 <2.5 130-160 330 25% Albumin 130-160 <2.5 130-160 330 Hartmann 131 5 111 29 280 Lactated Ringer s 130 4 3 109 28 273 6% Hetastarch 154 154 310 Gelofusine 154` 120

Problem with NS for fluid replacement High chloride content normal range 96-106 mmol/l NS at 154mmol/l, Slightly hyperosmolar More prone to develop hypercholemic acidosis Should consider lactate or Ringer s lactate or Hartmann solution

Hyponatremia despite Near Isotonic Saline infusion. A Phenomenon of Desalination, Steele etal. In Ann Intern Med, Jan 1997. 22 women underwent uncomplicated gynaecological operation.

Mortality with fluid retention

Positive Fluid Balance is Associated with higher Mortality and Prolonged Mechanical Ventilation in Pediatric Patients with Acute Lung Injury Heidi R flori etal, Critical Care Research and Practice 2011 - Study of 320 children with Acute Lung Injury - Associated with increase mortality and prolonged ventilator days

Fluid overload is associated with impaired oxygenation and morbidity in critically ill children, Arikan etal, PCCM 2012 - study on 80 patients with respiratory failure - independent of age, sex, and PLOD

Fluid balance in critically ill children with acute lung injury. Valentine etal, CCM 2012

Studies pro-inflammatory cytokine profiles in shock patients demonstrate that aggressive resuscitation attenuates the subsequent inflammatory response In short, aggressive early fluid resuscitation is useful

The overall strategy for the acutely ill child should be biphasic. Aggressive volume expansion to support tissue oxygen delivery as part of early goal-directed resuscitation algorithms for shock especially septic shock has been associated with dramatic improvements in outcome Identifying the point at which patients change from the early shock pattern to the later chronic critical illness pattern remains a major challenge.

Ogbu, Current Opinion in Critical Care 2015

Colloid solutions for fluid resuscitation (Cochrane Database Syst Rev. 2008) Seventy RCTs comparing colloid solutions in critically ill and surgical patients thought to need volume replacement, N = 4375 participants Albumin versus hydroxyethyl starch pooled RR 1.14 (95% CI 0.91 to 1.43) for mortality albumin versus dextran (RR= 3.75 95% CI 0.42 to 33.09). no evidence that one colloid solution is more effective or safe than any other

Summary Standard fluid calculation using Halliday and Seager formula is not safe in paediatric critical care practice Fluid requirement should be adjusted to underlying medical and surgical problems Watch out for excess fluid for ventilator cases Fluid overload is associated with increase morbidity and mortality Urine output alone might not be reliable

Thank you