Gastroenterology: Gastroenteritis Flashcards by Kirsty Sutherland

Is gastroenteritis a significant cause of morbidity in developed countries?

Yes - especially in younger children

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Is it a common reason for hospital admission in young children?

Yes

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What is the most frequent cause in developed countries?

Rotavirus - accounts for up to 60% of cases in children under 2 (particularly winter and early spring)
Adenovirus, norovirus, calicivirus, coronavirus, astrovirus can all cause outbreaks.

In countries with rotavirus vaccines, norovirus becoming leading cause

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Is an effective vaccination for rotavirus available?

Yes

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Are bacterial causes less common than viral in UK?

Yes

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What is likely to indicate a bacterial cause?

Blood in the stool

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What is the most common bacterial infection?

Campylobacter jejuni

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What is campylobacter jejuni infection associated with?

Severe abdominal pain

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Shigella and some salmonellae produce what type of infection?

Dysentery type - with blood and pus in the stool, pain and tenesmus

Shigella - high fever

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What infections are associated with profuse, rapidly dehydrating diarrhoea?

Cholera and enterotoxigenic E. coli

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What animal is campylobacter jejuni associated with?

Poultry - it naturally colonises to digestive tract of many bird species

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What examples of parasitic infections cause cause gastroenteritis?

Giardia

Cryptosporidium

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When should you suspect gastroenteritis?

If there is a sudden change is stool consistency to loose or watery stool. It is often accompanied by vomiting.

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How long does the diarrhoea usually last?

5-7 days and usually stops within 2 weeks

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How long does vomiting usually last?

1-2 days, in most within 3 days

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What is the most serious complication?

Dehydration leading to shock - its prevention or correction = main aim

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Which children are at an increased risk of dehydration?

Infants - particularly those under 6 months or those born with low birth weight
Passed 6 or more diarrhoea stools in previous 24 hours
Vomited 3 or more times in previous 24 hours
Unable to tolerate (or not been offered) extra fluids
If they have malnutrition

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Why are infants at a particular risk of dehydration?

They have a greater surface area to weight ratio than older children - greater insensible losses e.g sweating during fever
They have higher basal fluid requirements - due to faster metabolism
Immature renal tubular reabsorption - not as good at retaining water and less responsive to water preserving mechanisms
Unable to obtain fluids for themselves when thirsty

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What is the most accurate measure of dehydration?

The degree of weight loss during the diarrhoeal illness

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What important point are there when taking the history ?

Onset, frequency, duration
Was there blood in stool
Vomiting blood or green bile
How high has the fever been
How has her feeding been and how is it normally
How many wet nappies
Any other family contacts unwell/ recent foreign travel/ consumption of possible unsafe foods (takeaway, BBQ)
Recent medication use - especially antibiotics
Any problems during/ around time of child or siblings birth

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What 3 categories are used in the clinical assessment of dehydration?

No clinical dehydration
Clinical dehydration
Shock

What factors should be considered when assessing dehydration?

General appearance 
Conscious level
Urine output
Skin colour
Extremities
Eyes
Mucous membranes 
Heart rate 
Peripheral pulses 
Breathing
Capillary refill time
Skin turgor
BP 
Fontanelles

What signs/ symptoms correlate with clinical dehydration?

Appears unwell or deteriorating 
Altered responsiveness- irritable/ lethargic
Decreased UO
Normal skin colour
Warm extremities
Sunken eyes
Dry mucous membranes
Tachycardia
Tachypnoea
Normal peripheral pulses
Normal capillary refill
Reduced skin turgor
Normal BP

What signs/ symptoms indicate shock?

Appearing unwell or deteriorating 
Decreased level of consciousness 
UO decreased
Pale or mottled skin colour
Cold extremities 
Grossly sunken eyes
Dry mucous membranes 
Tachycardia 
Tachypnoea
Weak peripheral pulses
Prolonged capillary refill > 2 sec
Reduced skin turgor 
Hypotension - indicates decompensated

What investigations are done?

There is no need to send stool culture if typical viral gastroenteritis Children presenting with vomiting will usually have blood sugar check Bloods not routinely necessary - only required is shock, severe dehydration or electrolyte disturbance suspected or if IV fluids prescribed Blood culture if antibiotics started

When is a stool culture required?

``` If child appears septic Blood or mucus in stool Immunocompromised Foreign travel Symptoms lasting longer than 7 days ```

What differentials are there?

``` Systemic infections - sepsis, meningitis Local infections - UTI, pneumonia, otitis media Surgical - intussusception, pyloric stenosis, appendicitis, Hirschsprung disease GORD Metabolic - diabetic ketoacidosis Renal - haemolytic uraemic syndrome Intracranial pathology FPIES Coeliac disease Adrenal insufficiency ```

Are most cases of dehydration isonatraemic?

Yes In dehydration, there is a total body deficit of sodium and water. In most instances the losses of sodium and water are proportional and plasma sodium remains in normal range (isonatraemic dehydration)

What can happen when children with diarrhoea drink large quantities of water or other hypotonic solutions?

A greater net loss of sodium than water - fall in plasma sodium (hyponatraemic dehydration)

What does hyponatraemic dehydration lead to?

Shift of water from extracellular to intracellular compartments

The increase in intracellular volume in hyponatraemic dehydration can cause...

An increase in brain volume - may result in seizures.

The decrease in extracellular volume in hyponatraemic dehydration leads to..

Greater degree of shock per unit of water loss

Hyponatraemic dehydration is more common in..

Poorly nourished infants in developing countries

What happens in hypernatraemic dehydration?

Water loss exceeds the relative sodium loss and plasma sodium concentration increases

What does hypernatraemic dehydration usually result from?

High insensible water losses (high fever or hot dry environment) or from profuse low sodium diarrhoea

Describe the water shift In hypernatraemic dehydration

Shift into extracellular space from intracellular compartment.

What signs are less obvious in hypernatraemic dehydration?

Depression of fontanelles, reduced tissue elasticity, sunken eyes less obvious - this is because fluid has shifted from intracellular space to extracellular, so signs of extracellular fluid depletion are less per unit of fluid loss

Among what infants is hypernatraemic dehydration less obvious?

Obese infants

What can happen to the brain in hypernatraemic dehydration?

Water drawn out of brain and cerebral shrinkage occurs - may lead to jittery movements, increased muscle tone, hyperreflexia, altered consciousness, seizures, multiple small cerebral haemorrhages

Can hyperglycaemia occur with hypernatraemic dehydration?

Yes but it is transient and self correcting - does not require insulin

If there is no clinical dehydration, what is the management strategy?

To prevent dehydration - continue breastfeeding and other milk feeds - encourage fluid intake to compensate for increased GI losses - discourage fruit juices and carbonated drinks - oral rehydration solution as supplemental fluid if at increased risk

If there is clinical dehydration, what is the mainstay of therapy?

Oral rehydration solution

How should clinical dehydration be managed?

ORS (dioralyte): 50ml/kg over 4 hours plus maintenance requirements Continue breast feeding If not tolerating orally - NG ORS, consider ondansetron

How is clinical shock managed?

20ml/kg bolus of 0.9% saline Repeat if necessary - if remains in shock call CICU Symptoms and signs improve: IV therapy for rehydration- replace fluid deficit over 24 hours in most cases and give maintenance fluids

What should be done after rehydration?

Give full strength milk and reintroduce usual solid food Avoid fruit juices and carbonated drinks Parents - diligent hand washing, towels used by child not to be shared Do not return to childcare facility or school until 48 hours after last episode

How should hypernatraemic dehydration be managed?

ORS used for clinical dehydration. If IV fluids required: the fluid deficit should be replaced over at least 48 hours (with 0.9 or 0.45% saline) and plasma sodium measured regularly - aim to reduce less than 0.5mmol/hour

Why in hypernatraemic dehydration should IV fluid replacement be done slowly?

A rapid reduction in plasma sodium concentration and osmolality will lead to a shift of water into cerebral cells - seizures and cerebral oedema

Are antibiotics routinely required for the treatment of gastroenteritis?

No even if there is a bacterial cause. Only indicated for suspected sepsis, extra intestinal spread of bacterial infection, for salmonella gastroenteritis if aged under 6 months, in malnourished or immunocompromised children or for specific bacterial or protozoal infections (c.difficile associated with pseudomembranous colitis, cholera, shigellosis, giardiasis)

How will bacterial gastroenteritis present?

Systemically unwell child -possible neurological involvement High fever > 39 Bloody diarrhoea Abdominal pain Suspect in those with suspicious travel histories and unresolving symptoms or comorbidities such as IBD or immunodeficiencies

How does oral rehydration solution work?

It increases the absorption of salts and water in small intestine. ORS has high concentration of sodium and glucose - co transport occurs via SGLT1 into the cell (the gradient for this transport is maintained by Na/K ATPase). The movement of sodium from intestinal lumen into extracellular fluid creates a pull for water to follow.

When is IV fluid therapy required?

If child is in shock or unable to take fluids orally/ via NG

How would you describe the abdominal pain?

Vague and diffuse