30 October 2013

Acute Gastroenteritis (Medical students)

Definition of acute gastroenteritis (AGE) in children

Decrease in consistency of stools (loose or liquid), and/or the increase in the frequency of evacuation (typically more than 3 in 24 hours), with or without fever and vomiting. Diarrhoea typically lasts less than 7 days and not longer than 14 days.

Epidemiology

Rotavirus is the most frequent agent. A vaccine is available (given PO in 2 doses in the first 6 months of life). Other viral agents include Adenovirus, Norovirus and Astrovirus. Vomiting and respiratory symptoms are associated with viral aetiology.

Campylobacter and Salmonella are the most common bacterial agent. High fever, overt faecal blood, abdominal pain, CNS involvement (irritability, apathy, seizures) suggest bacterial aetiology.

Incidence: 0.5 – 2 episodes per child per year in children younger than 3 years. Breast-feeding reduces GE infections in European children. Day care attendance increases GE infections (compared to home care)

Assessment

History, physical examination and sometimes investigations. Two major considerations:
  1. Exclusion of other important causes of vomiting and diarrhoea (differential diagnosis)
  2. Adequate assessment and treatment of dehydration
Risk of Dehydration
  • Infants less than 6 months
  • Preterm
  • Malnourished
  • More than 6 diarrhoeal stools in 24 hours
  • More than 3 vomiting episodes in 24 hours
  • Unable to tolerate oral fluids
Assessment of Dehydration
  1. General appearance and conscious level
  2. Dry (skin turgor, eyes, tears, oral cavity, fontanelles)
  3. Cardio-respiratory (skin color, perfusion, cold extremities, tachycardia, weak pulses, BP, tachypnoea)
  4. Urine output
Classification:
  • No/minimal clinical dehydration: Child appears well, alert, has moist mucous membranes, normal skin turgor, good perfusion and heart rate, and normal urine output.
  • Significant clinical dehydration:  Child appears unwell, irritable or lethargic, has dry mouth, no tears, sunken eyes, decreased skin turgor; he is tachycardic and tachypnoeic, and oliguria.
  • CV Shock:  Decreased level of consciousness, cold extremities, pale/mottled skin, prolong CRT,  weak pulses, hypotension, and anuria.
Differential Diagnosis
  • Sepsis: UTI, otitis media, meningitis, pneumonia
  • Acute surgical abdomen: appendicitis, obstruction.
  • Diabetic ketoacidosis
Beware of labelling an infant with fever and vomiting as 'gastro-enteritis'. These non-specific symptoms could be the presenting signs of meningitis, pneumonia or UTI.

Hospitalisation
  • Severe dehydration/shock
  • Suspected surgical condition
  • High risk of dehydration (age, frequent diarrhoea/vomiting, not retaining oral fluids)
  • Severe underlying disease (diabetes, renal failure)
  • Caregiver cannot provide adequate care at home
Investigations

Stool cultures are not routinely performed. Stool cultures are taken (1) before antimicrobial treatment is started; (2) immunocompromised; (3) outbreaks.

Urea, creatinine, electrolytes, venous gases: measured in all children starting IV therapy. Normal bicarbonate value decreases likelihood of moderate (5%) dehydration.

Rehydration
  • ORS, glucose-facilitated sodium transport.
  • Oral rehydration should be first-line therapy.
  • When oral rehydration is not feasible, enteral is as effective as IV.
  • Enteral rehydration is associated with fewer major adverse events and is successful in most children.
Nutritional Management
  • Food should not be withdrawn for longer than 4 to 6 hours after the onset of rehydration.
  • Continue breast-feeding during gastroenteritis.
  • Formula dilution and regarding are not needed.
  • Normal feeding and age-appropriate food should be re-started no later than 4-6 hours after the onset of rehydration.
  • Lactose-free formula is seldom useful.
Pharmacological Therapy
  • Anti-emetics should not be routinely used to treat vomiting during AGE in children.
  • Loperamide and anti-diarrhoea agents should not be used.
  • Probiotics (Lactobacillus and Saccharomyces boulardii) are effective adjunct to the management of diarrhoea.
  • Antibiotics: Anti-infective therapy should not be given to the vast majority of otherwise healthy children with AGE. Antibiotics are indicated in severe invasive diarrhoea (bloody/mucous diarrhoea and high fever); Shigella (proven or suspected shigellosis); Salmonella (only in high-risk children); Campylobacter (mainly for the dysenteric form); Enterotoxigenic Escherichia coli (mainly for traveler’s diarrhea); Clostridium difficile (moderate and severe cases).
Hospital management
  • IV access – renal profile, bicarbonate
  • Treat shock with normal saline bolus/es.
  • IVI: 5% Dextrose in 0.45% N Saline +/- Potassium (according to se. K)
  • Rate = (maintenance + deficit)/24 hours
  • Clinical re-assessment and urine output
  • Hypernatraemic dehydration is corrected slowly to prevent a sudden drop in se Na which is associated with cerebral oedema and seizures.
  • Re-introduction of oral fluids and age-appropriate food.
Home management
  • Oral hydration (ORS) followed quickly by nutrition (Breast or formula milk, age-appropriate food. Avoid juices and fizzy drinks).
  • Temperature control and barrier cream.
  • Seek medical advice if (1) child not taking or keeping drink, no urine for 8 hours, lethargic; (2) getting worse; (2) parents more worried or not coping.
Case Histories

Case 1

8 month old infant brought to A&E on Saturday evening. His young mother requested admission because the child passed diarrhoea on three occasions. On clinical examination, the child looks well, alert and hydrated.

Do you think that this child requires admission?

Case 2

A 6 month old baby girl is brought to casualty. She had been seen 12 hours before for vomiting and diarrhoea, and treated at home with ORS and milk feeds. Her parents were anxious because she continued to pass diarrhoea and cried intermittently. Clinical examination shows an alert and well-hydrated child, the abdominal examination is normal.

How will you manage this case?

Case 3

2 month old baby boy presented with fever 38.2°C, crying and vomiting on 2 occasions. On clinical examination he was well hydrated, febrile, irritable. No signs of meningism. The abdomen is soft and slightly distended.

What is the diagnosis? What is your management?

Case 4

8 month old infant brought to casualty for spasmodic pain associated with pallor and irritability. He was afebrile and vomited twice.

What other questions would you ask the parents? Likely diagnosis? Any investigations?

Case 5

2 year old child presented with acute onset of vomiting, followed by watery diarrhoea. He complained of intermittent abdominal pain. He had low-grade fever, coryza, cough and nasal congestion. On examination he was well and alert and no signs of dehydration.

What is the likely diagnosis? How would you treat?

Case 6

A 3 year old girl presented acutely with nausea, vomiting and abdominal pain. She had been eating and drinking more than usual in the past two weeks. On examination she was severely dehydrated and tachypnoeic.

What immediate investigations would you perform?

Case 7

A 2 year old child was successfully treated for gastroenteritis with ORS. However on the re-introduction of a normal diet she again developed watery diarrhoea and perineal excoriations.

What is the likely cause? Treatment?