Paediatrics JC117: A Child With Loose Bowel

Question 1

GE in children

Answer 1

Etiology + Management vary with geographic region, socioeconomic situations, health service provision
BUT Majority of principles hold true

Question 2

History taking of GE in children

Answer 2

1. Clarification of chief complaint
   - Definition: **Alteration in normal bowel movement characterised by change in stool **consistency to loose / watery, with ↑ **frequency + **volume

• ***Acute / Chronic
• ***Character: Water vs bloody, Presence of mucus
  —> Watery stool without blood / mucus: Enterotoxin, Virus, Protozoan
  —> Blood stool with mucus (indicate mucosal inflammation, death of mucus-secreting cells in gut, capillary breakage): Cytotoxin-producing bacteria, Enteric parasites
• ***Frequency
• ***Volume

2. Severity assessment
   - No. of episodes (tricky in infants with nappies)
   - Frequency
   - Estimated amount (as judged by parents)
   - Consistency
   —> no absolute cutoff, only indicate change from baseline / normal pattern (depend on age, breast-feeding)
3. Concurrent symptoms
   - **Vomiting
   - **Fever
   - Poor appetite (quantify intake!)
   - ***Abdominal pain (often presents as Irritability, crying episodically (cramps, drawing up legs) not consolable!) —> Intussusception
4. **Dehydration / **Impaired perfusion
   - **Cry without tears
   - **Dry lips
   - **Cool limbs
   - **Urine output
   - ***Tiredness
   - Risk factors: Frequent profuse watery diarrhoea, Vomiting, Poor fluid intake, Concurrent fever (↑ insensible water loss)
   - Signs (parents can’t tell!): Pulse, Capillary refill, Sunken anterior fontanelle
5. Source (for infective cause)
   - What is the source
   - Usual intake
   - **Change in content
   - **Change in preparation: person, method, utensils
   - **Unhygienic food (e.g. undercooked food, raw food, eating out)
   - **Known contacts with persons having similar symptoms + hand hygiene not practised well (infective dose for adults much higher)
   - ***Nursery (outbreak)
   - Occupations of family members: cooks, kitchen workers (e.g. salmonella), health care workers
6. ***Epidemiological + Etiological considerations
   - Setting (Child-care centres, Institutions, Hospitals)
   - Family members, close contacts
   - Food-borne / Water-borne diarrhoea occurring after common exposure
   - Antimicrobial-associated diarrhoea
   - Diarrhoea of travellers
   - Diarrhoea in immunocompromised hosts (consider rarer pathogens)
   - History of chronic diarrhoea / underlying GI diseases
7. ***What has been done
   - Did mother give sufficient fluid?
   - How well does he tolerate?
   - Any medications taken?
   - Seen a doctor? What was done?
8. Past health, other related history
   - **Past health: recurrent diarrhoea? (suspect primary GI disease)
   - **Growth (failure to thrive?)
   - **Diet pattern (compare to baseline)
   - **Birth history (prior GI problem, preterm baby: NEC (Necrotising enterocolitis) related to prematurity, previous surgery, short gut syndrome)
   - ***Immunisation (rotavirus vaccine)
   - Family history
   - Social history

Question 3

DDx of acute-onset ***bloody stool, fever, abdominal cramps

Answer 3

1. ***Campylobacter
2. ***Shigella
3. ***Salmonella
4. C. difficile
5. Yersinia enterocolitis
6. Vibrio parahaemolyticus
7. Enteroinvasive E. coli
8. ***Enterohaemorrhagic E. coli (O157:H7)
9. ***Initial presentation of IBD

Question 4

Formulation of DDx of Acute + Chronic diarrhoea

Answer 4

Acute diarrhoea
1. Infective diarrhoea (most common cause of GE)
- Bacterial vs **Viral (>90% in children: **Rotavirus 輪狀病毒, **Norovirus 諾沃克病毒)
- **Secretory vs ***Inflammatory (mucus, blood in stool)

2. Food intolerance
   - Lactose
3. Osmotic agents
   - ***Toddler’s diarrhoea (∵ sudden ↑ intake of fruit juice, sucrose, sweeteners)
4. Drugs
   - Laxative

Chronic diarrhoea
- Repeated episodes otherwise unexplained by other causes
- Osmotic, Secretory, Malabsorptive, Motility, Inflammatory, Infective, Metabolic (***記: OSMMIIM)

Question 5

Acute infective GE: Etiology

Answer 5

***Rotavirus 輪狀病毒:
- most common cause of GE in children
- across community + hospital

Bacterial GE:
- **Salmonella
- **Campylobacter
- ***E. coli (O157, Non-O157)

Protozoal GE:
- ***Cryptosporidium (uncommon, consider after travelling, immunocompromised)

Pathogens associated with travelling:
1. **Salmonella (most common)
2. **Campylobacter, E. coli, Cryptosporidium
3. ***Shigella, Giardia, Entamoeba (Indian subcontinent, Sub-Saharan, Southern Africa)

Question 6

Acute GE: Duration + Natural history

Answer 6

Diarrhoea:
- usually lasts for ***5-7 days
- most stop within 2 weeks

Vomiting:
- lasts for ***1-2 days

Factors associated with more prolonged course:
- Co-infection of enteric pathogens (e.g. Salmonella + Rotavirus)
- Bloody / Mucoid stool (∵ indicate inflammation of GI epithelium + poor absorption of fluid —> require longer recovery)
- Malnutrition
- Indiscriminate use of antibiotics (∵ impair recovery of normal flora)

Question 7

DDx of Diarrhoea / Vomiting

Answer 7

GE

DDx other than GE:
1. **Non-enteric infections
- **Pneumonia
- **UTI
- **Meningitis
- Acute otitis media
- Toxic shock syndrome

2. **Non-infective GI disorders
   - IBD: UC, Crohn’s, Celiac disease
   —> **failure to thrive, weight loss, prolonged / bloody diarrhoea
3. ***Surgical disorders
   - Bowel obstruction
   - Intussusception
   - Ischaemic bowel
   - Acute appendicitis
   —> bilious vomiting, severe / localised abdominal pain, blood diarrhoea, rebound tenderness, abdominal distension, mucoid / bloody stools
4. Drug-related

Question 8

Assessment of dehydration + shock

Answer 8

1. Risk factors for dehydration:
   - children <1 yo (esp. <6 months)
   - low birthweight
   - **>=5 diarrhoeal stools in previous 24 hours
   - **>=2 vomiting in previous 24 hours
   - not been offered / not been able to tolerate supplementary fluids before presentation
   - ***stopped breastfeeding during the illness (no other routes of hydration)
   - signs of malnutrition
2. S/S (***記: Cardiovascular, Respiratory, Hydration status, Mental status)
   - Perfusion:
   —> Capillary refill
   —> Cool limbs
   —> Pulse
   —> Lips, BP (usually normal until severe dehydration ∵ compensation by HR)
   —> Skin mottling (self notes)
   —> Oral mucosa

• Hydration status
  —> Skin turgor (Flaccid (SpC Paed))
  —> Anterior fontanelle
  —> Eyes
  —> Urine output
  —> Oral mucosa (self notes)
• Mental status
• Red flags:
  —> Unwell appearance
  —> Tachycardia
  —> Tachypnea
  —> Sunken eyes
  —> Reduced skin turgor
  —> Altered responsiveness

Question 9

Hypernatraemic dehydration

Answer 9

Dehydration with plasma Na >150 mmol/L
- “Doughy skin” not reliable to identify patients with hypernatraemia dehydration (no reduced skin turgor)
- Severity of dehydration more often underestimated compared with normo-natraemic dehydration
- Suspect hypernatraemia dehydration if there are any of following of **CNS disturbance:
1. **Jittery movement
2. Increased muscle tone
3. Hyper-reflexia
4. **Convulsions
5. Drowsiness / **Coma

Question 10

Practical considerations for hospitalisation

Answer 10

When should a child with GE be hospitalised?
1. Red flag signs for significant **dehydration
2. Risk factors for significant **ongoing loss (esp. with severe vomiting compromising chance of success with oral rehydration —> need IV route)
3. Patients with grossly **bloody stool (i.e. blood loss —> need to exclude surgical causes)
4. Patients with **immunocompromised states (use of immunocompromised drugs, cytotoxic agents superimposed by opportunistic organisms)

Question 11

When to take blood?

Answer 11

1. Do NOT routinely perform blood biochemical testing
2. Measure plasma Na, K, urea, creatinine, glucose if:
   - IV fluid therapy required (to know baseline)
   - S/S suggest **hypernatraemia
   - infant with unexplained drowsiness: rule out **hypoglycaemia
3. Measure venous blood acid-base status + **chloride concentration if shock suspected / confirmed
   - dehydrated to a point of **lactic acidosis
   - never take ABG (too invasive)

Question 12

Acidosis in GE

Answer 12

Causes:
1. **Loss of HCO3 in acute diarrhoea
2. **Lactic acidosis in hypovolaemia shock (∵ impaired perfusion)

To distinguish between 2:
1. Normal Anion gap: HCO3 loss
2. ↑ Anion gap: Lactic acidosis (Impaired tissue perfusion)

(Anion gap = [Na] - [Cl] - [HCO3])

Question 13

Stool microbiological investigations

Answer 13

Community setting:
- Most acute GE in children are viral in origin
- Even if illness is caused by bacteria enteric infections —> most children do ***NOT require anti-microbial treatment
- Identification of specific pathogen not generally required

Hospital setting:
- Routine
- Isolation, Infection control purpose (PCR panel)

When necessary?
1. Diarrhoea + Systemic illness (e.g. High fever, Sepsis)
- ***Septic workup before administration of empirical antibiotic therapy

2. Presence of **mucus / **blood in stool
   - Bacterial / amoebic dysentery would require anti-microbial therapy
   - **Enterohaemorrhagic E. coli O157:H7 associated with **Haemolytic uraemic syndrome (HUS) (acute kidney failure, low RBC, low Plt) (uncommon)
   - **Antibiotic-related pseudomembranous colitis, caused by C. difficile (oral vancomycin, metronidazole)
   - Non-infective conditions e.g. if stool culture repeatedly negative —> **IBD should be considered
3. Returning traveler
4. Immunocompromised hosts (suspect opportunistic organisms)
5. Diarrhoea with prolonged course

Question 14

***Fluid management

Answer 14

Indication:
1. Primary prevention of dehydration in children with GE but without clinical dehydration
- **Continue breastfeeding + other milk feeds
- **Encourage fluid intake
- Discourage fruit juices + carbonated drinks (esp. those at risk of dehydration) (e.g. Pocari, glucose drinks: not better than water)
- Offer oral rehydration solution (ORS) as ***supplemental fluid (for those at risk of dehydration)

2. Rehydration in children with GE with dehydration (more common)
   - **Oral rehydration therapy (1st choice)
   —> replace fluid deficit (estimated by clinical S/S or body weight loss) in first 3-4 hours of rehydration phase (e.g. estimate **5% fluid loss —> if children is 10kg —> 500ml fluid replacement within 3-4 hours)
   —> continue breastfeeding + milk feeds
   —> **Small + **Frequent feeding (avoid giving large amount within short period)
   —> avoid fruit juices / carbonated drinks

• IV fluid therapy
  —> Signs of **shock
  —> **Impaired conscious state (hard to take fluid orally, also check electrolyte imbalance)
  —> Child with red flag S/S, showing clinical evidence of deterioration despite OR therapy
  —> **Failure of oral rehydration e.g. intolerance due to persistent vomiting
  —> **Paralytic ileus (peristalsis impaired (signs: abdominal distension, hypoactive bowel sounds) —> absorption impaired)

Question 15

ORS solutions

Answer 15

1. High-osmolarity solution (now not used anymore, previously for Malaria, Cholera)
2. Low-osmolarity solution
   - ↓ need for unscheduled IV fluid for treatment of dehydration in children with diarrhoea (compared to high-osmolarity)
   - greater ↓ in stool output + vomiting (compared to high-osmolarity)
   - only concern: HypoNa risk (compared to high-osmolarity)
3. Rice-based ORS (starch-based)
   - rice starch broken down into glucose by polysaccaridase + disaccharidase at brush border of intestinal villi
   - ***Na-glucose co-transporter promotes absorption of salts + water in lumen of intestinal villi
   —> help co-absorption of glucose + electrolytes across brushborder
   - evidence: ↓ duration of diarrhoea in children + more significant effect in those with Cholera

Question 16

***Oral rehydration strategy

Answer 16

Principle: **Small + **Frequent feeds

Aim: To replace **fluid deficit over 4 hours
- Ensure appropriate amount of **maintenance fluid is administered to the child
- Monitor for ***ongoing loss + replace accordingly
- Assess for fluid intolerance
- May need to adjust strategy of rehydration according to child’s response to oral rehydration therapy
—> Key: Reassess + Reassess + Reassess

***Total fluid needed: Fluid deficit + Maintenance fluid volume + Ongoing loss

Fluid deficit (SpC Paed + Felix Lai):
- BW x % dehydration x 1000 —> 1% dehydration —> 10ml/kg fluid deficit

Ongoing loss (Felix Lai):
- Each watery / loose stool = 5 ml/kg
- Each vomiting episode = 2 ml/kg

Question 17

***Maintenance fluid volume calculation (記)

Answer 17

Per day (***記: 100, 50, 20)
0-10 kg: 100 ml/kg
10-20 kg: 1000 ml + 50 ml/kg for each kg >10
>20kg: 1500 ml + 20 ml/kg for each kg >20

***Total fluid needed: Fluid deficit (5%) + Maintenance fluid volume + Ongoing loss

Example: 10kg child
- Fluid deficit: 500ml
- Maintenance fluid volume: 1000ml
- Ongoing loss: depends
—> Total fluid needed = 500ml + 1000ml + Ongoing loss

Question 18

IV fluid rehydration

Answer 18

• WHO: correct fluid deficit completed in 3-6 hours
• Attempt ***early + gradual introduction of OR therapy during IV therapy
• If tolerated —> stop IV fluid + complete rehydration with oral rehydration therapy

Question 19

***Treatment of Shock

Answer 19

Shock
—> Rapid IV infusion of **0.9% NaCl (20 ml/kg)
—> Persistent signs of shock
—> Another Rapid IV infusion of **0.9% NaCl (20 ml/kg)
—> Consider possible ***causes of shock other than dehydration

—> Signs of shock resolved —> Continue rehydration with IV fluid
—> Persistent signs of shock —> Consult intensive care specialist

Question 20

Treatment of hypernatraemic dehydration

Answer 20

Isotonic solution e.g. 0.9% NaCl for fluid deficit replacement + maintenance
- replace fluid deficit **slowly (over 48 hours)
- **monitor plasma Na frequently
- aim at reduce Na at a rate of ***<0.5 mmol/L/hour

Question 21

Fluid management after rehydration

Answer 21

1. Encourage breastfeeding + other milk feeds
2. Encourage fluid intake
3. Prevent recurrence of dehydration by replacing ongoing loss form diarrhoea with **additional ORS (e.g. **5-10 ml/kg per large watery stool), esp. for at-risk groups:
   - children <1 yo (esp. <6 months)
   - low birthweight
   - >=5 diarrhoeal stools in previous 24 hours
   - >=2 vomiting in previous 24 hours
4. Restart OR therapy if dehydration recurs after rehydration

Question 22

Nutritional management

Answer 22

1. Re-introduce usual feeding early, including solid food
2. No evidence that dilute milk is of benefit, give ***full-strength milk as usual
3. Available evidence shows ***no benefit from special milk formulas e.g. lactose-free / soy-based formula

Question 23

Anti-emetics

Answer 23

• Target CNS / GI
• Have SE + not target primary cause of GE
• NOT recommend as routine use in management of GE

1. Promethazine (Phenergan)
   - Anti-H1
   - Anticholinergic
   - Anti-dopaminergic activity —> ***extrapyramidal symptoms: dystonic reactions of facial / skeletal muscles, oculogyric crisis, NOT use in children
2. Metoclopramide (Maxolon)
   - Anti-D2 —> ***extrapyramidal symptoms: dystonic reactions of facial / skeletal muscles, oculogyric crisis, NOT use in children
   - weak Anti-5HT3 activity
3. Ondansetron (Zofran)
   - Potent
   - highly-selective Anti-5HT3
   - can ↓ occurrence of persistent vomiting, success of oral rehydration —> ↓ use of IV fluid
   - but frequency of stool passage ↑ with ondansetron
   —> alter natural course of GE (may make situation worse)
   —> ∵ result of retention of fluids + toxin that would have been eliminated through vomiting (由嘔變痾)
   —> most children have self-limiting vomiting —> routine use of ondansetron NOT recommended

Question 24

Anti-diarrhoeal agents

Answer 24

Commonly prescribed agents in medical practice:
- Adsorbents e.g. kaolin, smectite
- Anti-motility agents e.g. loperamide

No high-level evidence available for benefit of anti-diarrhoeals —> ***NOT recommended

Potentially serious adverse SE:
- increase in intestinal transit time **reduce clearance of pathogens / toxins
- abdominal distension
- **ileus
- drowsiness in loperamide

Question 25

Probiotics

Answer 25

Lactobacillus, Bifidobacillus, Saccharomyces yeast

Possible mechanism:
1. Compete with pathogens for binding sites / substrates
2. ↓ Intestinal luminal pH
3. Upregulation of genes mediating immunity
4. Production of tropic short-chain fatty acids to promote mucosal cell growth + differentiation

Some evidence of possible clinical benefits (with specific formulations e.g. Lactobacillus caseii GG) as a useful adjunct to rehydration therapy

Question 26

Antibiotics

Answer 26

• Most acute GE in children are self-limiting
• Viral infection do not require antibiotic treatment

Give antibiotics when:
1. Suspected / Confirmed **septicaemia
2. Extra-intestinal spread of bacterial infection
3. Patient <6 month with **Salmonella GE
4. Patient malnourished / immunocompromised with **Salmonella GE
5. **C. difficile associated pseudomembranous enterocolitis
6. **Giardiasis
7. Dysentery by **Shigella
8. **Amoebic dysentery
9. **Cholera

Question 27

Discharge plan

Answer 27

When to discharge:
1. Rehydration completed
2. Minimal risk for dehydration recurrence
3. Uncomplicated disease course

Other considerations:
1. Reliable care: capability of child care
2. Understanding of carer to your treatment plan: any previous experience in managing a child with GE, myths / misunderstanding

Question 28

Information / Advice for parents / carers

Answer 28

• Most children with GE can be safely managed at home
• Empower parents / carers

Advice:
1. Continue usual feeds, including breastfeeding / other milk feeds
2. Encourage child to drink plenty of fluids
3. Discourage over-consumption of fruit juices and carbonated drinks
4. Offer ORS solution as supplemental fluid (esp. in presence of ongoing loss)
5. Fluids should be given **frequently in **small portions
6. Watch out for S/S of dehydration:
- appear unwell
- altered responsiveness, irritability, lethargy
- ↓ urine output
- pale, mottled skin
- cold extremities
7. Seek medical attention if symptoms of dehydration develops
8. Seek medical attention if **disease course is atypical
- usual duration of diarrhoea 5-7 days, in most children stops within **2 weeks
- usual duration of vomiting 1-2 days, in most within ***3 days

Question 29

GE: Epidemiology

Answer 29

Death due to diarrhoea: ~10% worldwide

GE in developed world:
- deaths associated with GE rare
- 2nd most common cause of hospitalisation / doctor visits
- ***Rotavirus: 25-55% of all hospitalisations for GE

Issues in developing countries:
- Access to clean drinking water
- Sanitation
- Malnutrition

Protect:
- **exclusive BF for 6 months
- **adequate complementary feeding
- Vit A supplementation

Prevent:
- **vaccines: pertussis, measles, Hib, PCV, rotavirus
- **handwashing
- ***safe drinking water + sanitation

Treat:
- improve care seeking + referral
- improve case management at community + health facility levels
- continued feeding

Question 30

Principles of fluid therapy (SpC Paed E-learning: Fluid And Electrolytes Therapy)

Answer 30

Total daily fluid = Maintenance + Deficit + Ongoing loss

Speed of rehydration:
- Depends on type of dehydration, chronicity of the problem, whether patient is acutely symptomatic

Loss of water per 100 calories:
- 45ml insensible loss —> 30ml skin + 15ml lung
- 50ml renal loss
- 10ml sweat loss
- 5ml stool loss

Holliday-Segar method:
- Caloric expenditure predicts H2O requirement
- NOT suitable for neonates
- 1st 10kg —> 100ml/kg/day —> 4ml/kg/hour
- 2nd 10kg —> 50ml/kg/day —> 2ml/kg/hour
- Each additional kg —> 20ml/kg/day —> 1ml/kg/hour
- Max: 2400ml/day (100ml/hour)

Neonates:
- Day 1: 60ml/kg/day
- Day 2: 90ml/kg/day
- Day 3: 120ml/kg/day
- Day 4 - 1month: 150ml/kg/day
- Increase if small body size / prematurity / fever / dehydration / gut loss-

BSA method:
- NOT used for children <10kg
- Water required = 1500ml/m2/day (Insensible water loss = 400ml/m2/day)
- BSA (m2) = (√(Height (cm) x BW (kg))) / 60

Question 31

Electrolytes

Answer 31

Na:
- Daily requirement: 2-3 mmol/kg/day
- 5.85% NaCl: 1ml —> 1 mmol Na
- 23.4% NaCl: 1ml —> 4 mmol Na
- NaCl tab 900mg —> 17 mmol Na

K:
- Daily requirement: 2 mmol/kg/day
- 14.9 KCl: 1ml —> 2 mmol K
- K2PO4: 1mol —> 2.5 mmol K + 1.5 mmol PO4
- Syrup KCL: 1g —> 13.3 mmol K
- Slow K tab: 600mg —> 8 mmol K
- Max conc of IV K supplement infusion:
—> Peripheral vein: <40 mmol/L
—> Central vein: up to 80 mmol/L
- Max rate <=0.5 mmol/kg/hour
- Oral replacement for hypoK: 1-4 mmol/kg/day + monitor serum K
- IV replacement: 0.5-1 mmol/kg/dose as an infusion of 0.5 mmol/kg/hour over 1-2 hours
- NEVER administer IV K bolus + undiluted —> MUST be diluted + infusion + slow rate
- Conisder whether K is required
—> 一般黎講唔使
—> Should be avoided if possible unless pre-made fluid bags containing K are available
—> Adding K to bags of fluid is a safety risk
—> Ensure adequate urine output before adding K
—> In absence of hypoK, 20-30 mmol/L KCl is adequate

Ca:
- Daily requirement: 1 mmol/kg/day
- 10% Ca gluconate: 1ml —> 0.22 mmol
- 10% CaCl2: 1ml —> 0.68 mmol
- MUST dilute before infusion
- Beware of extravasation

PO4:
- Daily requirement: 0.7-1 mmol/kg/day
- Usually no need to replace since diet can already replenish (except DKA, RTA, Refeeding syndrome)
- IV KH2PO4 + K2HPO4: 1ml —> 2.5 mmol K + 1.5 mmol PO4
- IV Na glycophosphate: 1ml —> 1 mmol PO4, 2 mmol Na
- Phosphate Sandoz 1 tab: 16.1 mmol PO4
- Na phosphate oral solution: 5ml —> 7 mmol PO4

Mg:
- Daily requirement: 0.1-0.3 mmol/kg/day
- Check whether HypoMg causing HypoK / HypoCa
- 49.3% MgSO4: 1ml —> 2 mmol Mg
- Treatment dose: 0.2 ml/kg/dose Q12H for 2-3 doses (dilution >1:5)
- Mg tab 3.5 mmol/84mg tab

Question 32

Commonly used IV fluids

Answer 32

• Dextrose solution: 5% (D5), 10% (D10)
• Normal saline (NS): 0.9% NaCl (Na 154 mmol/L) —> usually only for acutely ill / post-op / SIADH

Hypotonic solution:
- 1/2 solution: 0.45% NaCl + 2.5% Dextrose (Na 77 mmol/L) —> 夠用
- 1/3 solution: 0.3% NaCl + 3.3% Dextrose (Na 51 mmol/L)
- 1/5 solution: 0.18% NaCl + 4.3% Dextrose (Na 31 mmol/L)

Pre-made standard solution with KCl:
- 1/2 solution with 20 mmol/L KCl
- 1/2 solution with 40 mmol/L KCl

Question 33

How much fluid?

Answer 33

Hypovolaemia:
Bolus:
- 10-20 ml/kg of 0.9% NaCl —> Can be repeated
- Consult PICU if >40-60 ml/kg required (e.g. due to septic shock, cardiogenic shock —> may need inotrope instead)
- NOT include this fluid volume in any subsequent calculations

Maintenance + Deficit + Ongoing loss (e.g. in GE, drain losses, ileostomies):
- Generally 2/3 of maintenance rate should be used in unwell children (e.g. meningitis / other CNS conditions —> likely secreting ADH) unless they are dehydrated

Question 34

Dehydration

Answer 34

1% dehydration —> 10ml/kg fluid deficit

BW x % dehydration x 1000 (Felix Lai)

Older child:
- Mild: 3% dehydration (30ml/kg fluid deficit)
- Moderate: 6% dehydration
- Severe: 9% dehydration

Infant:
- Mild: 5% dehydration
- Moderate: 10% dehydration
- Severe: 15% dehydration

Rate of correction of HypoNa dehydration vs HyperNa dehydration:
HypoNa dehydration:
- Rapid correction —> Central pontine myelinolysis, only for symptomatic patients
- Rate of rise should NOT >0.5-1 mmol/L/hour or 10-12 mmol/L in 24 hours

HyperNa dehydration:
- Avoid dropping Na by >15 mmol/L in 24 hours —> Cerebral edema risk
- Replace deficit over 48 hours

Question 35

Monitoring

Answer 35

• Baseline: BW, Electrolytes, Glucose
• After fluid commencement: BW, Electrolytes daily
• For more unwell children —> Q4-6H after fluid commencement (at least daily)

Question 36

Children at risk of SIADH + Assessment of HypoNa

Answer 36

1. Post-op / Immobilised children
2. CNS disease (Meningitis, Status epilepticus, Encephalitis)
3. Cardiac dysfunction
4. Liver disease
5. Nephrotic syndrome
6. Pulmonary disease
7. Hypothyroidism
8. Hypoadrenalism
9. Stress, nausea, vomiting, pain
10. Medications (e.g. Vincristine, Carbamazepine, Cyclophosphamide, SSRI)

Assessment of HypoNa:
- Assess symptoms + underlying cause
- Assess hydration status, urine output
- Check RFT, serum osmo, urine osmo, Na, Cr
- Calculate fractional excretion of Na (FeNa): (Urine Na x Serum Cr) / (Serum Na X Urine Cr)
- Normal FeNa: 1% in infant, <0.5% in children (∵ normal kidney preserve Na)