Gastroenteritis

Gastroenteritis

differential diagnoses
1. infection
  1. systemic
    1. septicaemia
    2. meningitis
  2. local
    1. resp tract infection
    2. otitis media
    3. hepatitis A
    4. UTI
2. surgical disorders
  1. pyloric stenosis
  2. intussusception
  3. acute appendicitis
  4. necrotising enterocolitis
  5. Hirschsprung disease
3. metabolic disorder
  1. diabetic ketoacidosis
4. renal disorder
  1. haemolytic uraemic syn
5. other
  1. coeliac disease
  2. cow's milk protein intolerance
  3. adrenal insufficiency
epidemiology
1. developing countries
  1. major cause of child mortality
2. developing countries
  1. major cause of child morbidity
  2. UK
    1. 10% of 5 yr olds annually
causes
1. viral
  1. rotavirus
    1. commonest cause in developed countries
    2. accounts for 60% of cases in <2 yr olds
    3. effective vaccine available
      1. not part of national immunisation programme
  2. cause outbreaks
    1. adenovirus
    2. norovirus
    3. calicivirus
    4. coronavirus
    5. astrovirus
2. bacterial
  1. less common in developed countries
    1. Campylobacter jejuni
      1. commonest bacterial infection in developed countries
      2. assoc w/ severe abdo pain
    2. Shigella, some Salmonella spp.
      1. dysentry
      2. blood and pus in stool
      3. pain
      4. tenesmus
      5. Shigella may be acc by high fever
  2. blood in stool
  3. clinical features are poor guide to the pathogen
  4. cholera and enterotoxic E. coli
    1. profuse, rapidly dehydrating diarrhoea
clinical features
1. sudden change to loose or watery stools
  1. often + vomiting
2. contact w/ a person w/ diarrhoea
3. recent travel abroad
complication
1. dehydration
  1. increased risk of dehydration in
    1. infants
      1. esp < 6months old or born w/ low birth weight
      2. at greater risk than older kids
        infants have higher surface area:weight
        -> greater insensible losses
        infants have higher basal fluid requirements
        10-12% of body weight
        infants have immature renal tubular absorption
        infants can't get fluid for themselves when thirsty
    2. children passed 6 or more diarrhoeal stools in prev 24 hours
    3. children vomited 3 or more times in prev 24h
    4. children unable to tolerate (or not been offered extra fluids)
    5. children w/ malnutrition
  2. Rx aims to prevent or correct this
  3. -> shock
  4. types
    1. isonatraemic
      1. loss of water and Na+ are proportional
        so plasma Na+ within normal range
    2. hyponatraemic
      1. when kids w/ diarrhoea drink large amounts of water or other hypotonic sols
        -> greater net loss of Na+ than water
        -> fall in plasma Na+
        -> water shifting from extracellular to intracellular comp
        -> increase in brain vol
        ->convulsions
        greater degree of shock per unit of water loss
        due to marked extracellular depletion
      2. more common in poorly nourished infants in developing countries
    3. hypernatraemic
      1. infrequent
      2. water loss exceeds relative Na+ loss
        plasma [Na+] increases
        usually results from high insensible water losses
        high fever or hot dry env
        can result from profuse low Na+ diarrhoea
        extracellular fluid becomes hypertonic vs intracellular fluid
        -> shift of water into extracellular space from intracellular
      3. signs of fluid depletion less obvious
        so hard to recognise this type of dehydration clinically
        esp in obese infants
      4. dangerous form of dehydration
        water is drawn out of brain
        cerebral shrinkage within a rigid skull ->
        jittery movements
        increased muscle tone
        with hyperreflexia
        altered consciousness
        seizures
        multiple, small cerebral haemorrhages
        transient hyperglycaemia
        self-correcting
        no need for insulin
  5. total body deficit of Na+ & water
Mx
1. assessment of dehydration
  1. degree of weight loss during diarrhoeal illness
    1. most accurate measure of dehydration
  2. use hx and examination
    1. degree of dehydration
      1. no clinically detectable dehydration
        usually 5% loss of body weight
      2. clinical dehydration (usually 5-10%)
      3. shock
        > 10% loss of body weight
        clinical features
        decreased levels of consciousness
        sunken fontanelle
        dry mucous mbs
        eyes sunken and tearless
        pale mottled skin
        increased resp rate
        prolonged capillary refill time (> 2 secs)
        increased heart rate
        weak peripheral pulses
        hypotension
        reduced skin turgor
        sudden weight loss
        cold extremities
        reduced urine output

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	Created by v.djabatey almost 11 years ago