Acute gastroenteritis in children

浙江大学医学院附属儿童医院

江米足

What is Gastroenteritis? Gastroenteritis: nausea, vomiting, diarrhea, abdo

minal cramping, and fever occur 6-48h after exposure.

Gastroenteritis is second only to respiratory illness as a cause of childhood morbidity worldwide.

Most gastroenteritis is caused by viral infection; bacterial, parasitic (protozoal illnesses are less frequent but not uncommon) and Fungi.

Acute gastroenteritis Description:

viral gastroenteritis self-limited illness with nausea, vomiting,

diarrhea Organs involved:

limited to gastrointestinal tract (small intestine) Who is most affected:

children aged 6 months to 2 years rotavirus can cause acute diarrhea

What is diarrhea? Definition: the passage of excessively liquid o

r frequent stools with increased water content . Loose consistency( 性状改变 ): watery diarrhea,

mucous diarrhea, bloody diarrhea Increased stool frequency( 次数增多 )

Duration Acute (< 14 d) Persistent (14 d to 2 m) Chronic (> 2 m)

Infective Non infective

Viruses Bacteria Parasites

Fungi

Food Allergy

Symptomatic

Overfeeding

Intolerance

Climate

Etiology of Diarrhea

Common Infectious Causes of Diarrhea

Viruses Rotavirus

Astrovirus

Calicivirus (including norovirus)

Enteric adenovirus

Common Infectious Causes of Diarrhea

Bacteria Campylobacter jejuni Escherichia coli

EPEC; ETEC; EITC; STEC; EAEC Shigella Salmonella Yersinia enterocolitica Staphylococcus aureus Clostridium difficile Vibrio cholerae Vibrio parahemolyticus

Common Infectious Causes of Diarrhea

Parasites

Entamoeba histolytica (ambiasis)

Giardia lamblia

Cruptosporidium parvum ( 隐孢子虫 ) Strongyloides stercoralis （粪类园线虫） Blastocystishominis ( 人牙囊原虫）

Fungi

Candida albicans

Causes of acute gastroenteritis in children

Viruses (about 70%) Rotaviruses Noroviruses Enteric adenoviruses Caliciviruses Astroviruses Enteroviruses

Protozoa (<10%) Cryptosporidium Giardia lamblia Entamoeba histolytica

Bacteria (10-20%) Campylobacter jejuni Non-typhoid Salmonella spp Enteropathogenic Escherichia c

oli Shigella spp Yersinia enterocolitica Shiga toxin producing E coli Salmonella typhi and S paratyp

hi Vibrio cholerae

Helminths Strongyloides stercoralis

Rotavirus and diarrhea

As with most viral pathogens, rotavirus affects the small intestine, causing voluminous watery diarrhea without leukocytes or blood.

Rotavirus, a 67-nm double-stranded RNA virus with at least eight serotypic variants, is the most common.

Rotavirus a REOvirus (Respiratory Enteric Orphan virus) 4 serotypes based on viral hemagglutinin (Gro

up A rotavirus is most common, but group B and C infections have been documented)

transmission - fecal-oral, respiratory droplet virus resistant to stomach acid, attaches to be

ta receptor shedding of rotavirus can last up to 2 months

after severe rotavirus diarrhea rotavirus can survive on dry inanimate surface

s for 6-60 days

Mechanisms of diarrhea

Osmotic

Secretory

Mucosal inflammation (invasion)

Motality

Mechanisms of Diarrhea Osmotic

Defect Digestive enzyme deficiencies

Ingestion of unabsorbable solute

ExampleViral infection

Lactase deficiency

Sorbitol /magnesium sulfate

CommentStop with fasting

No stool WBCs

Mechanisms of Diarrhea Secretory

Defect Increased secretion Decreased absorptionExample Cholera Toxinogenic E.coliComment Persists during fasting No stool leukocytes

Mechanisms of Diarrhea Invasion

DefectInflammationDecreased colonic reabsorptionIncreased motility

ExampleBacterial enteritis

CommentBlood, mucus and WBCs in stool

Mechanisms of Diarrhea

Increased motility

DefectDecreased transit time

Example:

Irritable bowel syndrome

Common infectious causes of diarrhea and their virulent mechanism

Viral diarrhea (osmotic) Rotavirus

Bacterial diarrhea Enterotoxinogenic enteritis (secretory)

ETEC Vibrio cholerae

Entero-invasive enteritis (invasion) Campylobacter jejuni EIEC Shigella species Salmonella tymphimurium Yersinia enterocolitica

Pathogenesis of enterotoxinogenic enteritis

The mucosa is not destroyed during this process

An imbalance in the ratio of intestinal

fluid absorption to secretion, so

watery stoolwatery stool may occur in clinical

observation

Complications of acute gastroenteritis

Dehydration Metabolic acidosis Electrolyte disturbance (hypernatraemia, hyponatraemi

a, hypokalaemia, neonatal hypocalcemia ) Carbohydrate (lactose, glucose) intolerance Susceptibility to reinfection Development of food (cow’s milk, soy protein) intolera

nce Haemolytic uraemic syndrome Iatrogenic complications (due to inappropriate composi

tion or amount of intravenous fluids) Death

What are the clinical characteristics?

Viral infection, with rotaviruses and noroviruses being most common.

Viral infections damage small bowel enterocytes and cause low grade fever and watery diarrhoea without blood.

Rotavirus infection is seasonal in temperate climates, peaking in late winter, but occurs throughout the year in the tropics.

Rotavirus strains vary by season and geographically within countries.

The peak age for infection is between 6 months and 2 years, the mode of spread is by the faecal-oral or respiratory route

How is it diagnosed? Diagnosis can be made clinically. Information include

recent contact with people with gastroenteritis, nature and frequency of stool and vomitus, fluid intake and urine output, Travel use of antibiotics and other drugs

Diarrhoea and vomiting are non-specific symptoms in young children,

high fever prolonged symptoms signs suggesting a surgical cause (such as severe abdominal pa

in, bilious vomiting, abdominal mass). Children with diabetes mellitus and inborn errors of me

tabolism may present with vomiting.

History

Chief concern (CC): acute self-limited diarrhea nausea vomiting most infections in newborns are

asymptomatic or mild

Clinical manifestation Gastrointestinal symptom

Acute gastroenteritis—diarrhoea or vomiting (or both) of more than seven days duration

Systemic symptom May be accompanied by fever, abdominal pain, and

anorexia.

Dehydration and electrolyte disturbances Dehydration Hypokalemia Metabolic Acidosis Hypocalcemia /Hypomagnesemia

Physical

General physical up to one-third have fever > 102

degrees F (39 ℃) evaluation of dehydration in

children

How is dehydration assessed?

It is important to assess hydration in gastroenteritis as hydration status determines the immediate management of this condition.

The infant or child with profuse watery diarrhoea and frequent vomiting is most at risk.

Clinicians often overestimate the extent of dehydration. Documented recent weight lost is a good indicator of th

e degree of dehydration, but this information is rarely available.

The best clinical indicators of more than 5% dehydration are prolonged capillary refill, abnormal skin turgor, and absent tears

Degree of dehydrationClinical signs mild moderate severeDecrease in body weight 3-5% 5-10% 10-15%Skin Turgor normal decreased Markedly decreas

ed Color normal pale markedly decreased Mucous membranes Dry Mottled or gray;

parchedHemodynamic signs Pulse normal slight increase tachycardia Capillary refill 2-3 s 3-4 s >4 s blood pressure normal low perfusion normal circulatory collapseFluid loss urinary output mild oliguria oliguria anuria Tears Decreased absentUrinary indices specific gravity >1.020 anuria Urine [Na+] <20mEq/L anuria

Clinical dehydration scale (CDS)

clinical dehydration scale (CDS) using 4 exam features predicts length of stay and likelihood of receiving IV rehydration in young children having acute gastroenteritis

CDS points assigned General appearance

0 normal 1 thirsty, restless, lethargic but irritable when

touched 2 drowsy, limp, cold, sweaty, comatose

Eyes 0 normal 1 slightly sunken 2 very sunken

Mucous membranes (tongue) 0 moist 1 sticky 2 dry

Tears 0 present 1 decreased 2 absent

CDS classify

CDS (ranges from 0-8 points) classifies children into 3 degrees of dehydration 0 points - no dehydration 1-4 points - some dehydration 5-8 points - moderate/severe

dehydration

Type of dehydration

Isotonic (isonatreIsotonic (isonatremic)mic)

Hypertonic (hypHypertonic (hypernatremic)ernatremic)

Hypotonic (hypoHypotonic (hyponatremic)natremic)

Loses H2O = Na H2O > Na H2O < Na

Plasma osmolality

Normal Increase Decrease

Serum Na+ Normal Increase

>150mmol/L

Decrease

<130mmol/L

ECV

ICV

Decrease maintained

Decrease

Decrease +++

Decrease +++

Increase

Thirst ++ +++ +/-

Skin turgor ++ Not lost +++

Mental state Irritable/lethargic Very irritable Lethargy/coma

shock In severe cases Uncommon Common

Laboratory test Initial laboratory evaluation

CBC Stool examination: mucus, blood, and leukocytes Gas and electrolytes analysis BUN, Cr, and urinalysis for specific gravity

Rapid test for Rotavirus Stool culture

for patients with fever, profuse diarrhea, and dehydration or if HUS is suspected

Stool evaluation for parasitic agents identification of the organism in the stool

Blood culture uncommom

What to exclude (differential diagnosis)

Other infections, such as urinary tract infection, otitis media, pneumonia, septicemia

Surgical causes, such as intussusception, appendicitis, small intestinal obstruction (including malrotation)

Taking antibiotics or other drugs Spurious diarrhoea; for example, in chronic constipati

on with overflow incontinence Non-infectious diseases such as diabetic ketoacidosis,

inborn errors of metabolism Occasionally acute infectious gastroenteritis unmasks

gastrointestinal disease (such as coeliac disease, chronic inflammatory bowel disease)

How is gastroenteritis treated? Management aims to prevent and treat deh

ydration, maintain nutrition, and minimise harm.

Optimal management with oral or intravenous fluids minimises the risk of dehydration and its adverse outcomes.

Routine use of drugs such as antibiotics, antidiarrhoeal agents, and antiemetics is not recommended and may cause harm.

Which fluid therapy? Most children are not dehydrated and can b

e managed at home Dehydration, metabolic acidosis, and electr

olyte disturbance can be prevented and treated by fluid therapy

Mild-moderate dehydration can be treated with oral or enteral rehydration using low osmolality oral rehydration solutions (ORS)

Severely dehydrated or shocked children usually need intravenous fluids and hospital admission

Oral rehydration ORS are preferable to other clear fluids for

preventing and treating dehydration Fluids high in sugar (such as cola, apple juic

e, and sports drinks, which contain ≤20 mmol/l sodium and have a high osmolality of 350-750 mOsm/l) may exacerbate diarrhoea and should be avoided.

Breast feeding should be continued during acute gastroenteritis and supplemented with an oral rehydration solution if needed.

Which oral rehydration solution?

Solutions with low osmolality (200-250 mOsm/l) and sodium (60-70 mmol/l) that contain glucose, potassium, and a base (such as citrate) are recommended for developed and developing communities.

ZJCH

成份 标准 ORS（第一代）

标准 ORS（第二代）

WHO低渗 ORS

ESPGN低渗 ORS

钠 90 90 75 60

氯 80 80 65 45

无水葡萄糖 111 111 75 90

钾 20 20 20 25

枸橼酸盐 - 10 10 20

碳酸氢盐 30 - - -

渗透压（张力） (mOsm/L)

311 （ 200 ）2/3 张

311 （ 200 ）2/3 张

245 （ 170 ）1/2 张

240 （ 150 ）1/2 张

低渗 ORS 的常用配方

If oral intake is inadequate because they dislike the taste, feel nauseated, or have profuse vomiting, a fine bore nasogastric tube is usually well tolerated. Alternatively, fluids may be given intravenously.

Enteral (oral or nasogastric) and intravenous fluids are equally safe and effective for mild-moderate dehydration, rehydration can usually be achieved in 4 to 6 hours.

Children with shock require intravenous resuscitation before rehydration.

Iatrogenic complications The most common adverse effect of intravenou

s cannulation is infiltration at the cannula site, but infection, pain, bleeding, and physical and emotional trauma may also occur

especially electrolyte disturbance due to inappropriate composition, rate of administration, or volume of intravenous fluids—may lead to complications, including hyponatraemia with brain injury or death.

If rapid intravenous rehydration is used, careful supervision is needed to avoid fluid overload (dehydration is often overestimated) and electrolyte imbalance.

What about diet? Children should resume their normal diet o

nce their appetite returns. Recommend early reintroduction of milk an

d solids including complex carbohydrates, lean meats, yogurt, and vegetables, but foods high in fat and sugars should be avoided.

Early refeeding reduces the duration of diarrhoea.

In formula fed infants feeds do not need to be diluted when reintroduced.

Is a lactose-free diet necessary? Carbohydrate (particularly lactose) intolera

nce is a common complication of viral gastroenteritis as a result of damage to and loss of mature enterocytes containing lactase.

Lactose intolerance is usually mild and self limiting and does not require treatment.

If lactose intolerance persists, a lactose-free formula is recommended for four to six weeks.

Intolerance to food proteins The damaged gut is more permeable t

o foreign antigens. Intolerance to food proteins (β lactogl

obulin in cow’s milk and other proteins) is occasionally seen after gastroenteritis;

Can be managed by a period of dietary exclusion.

What is the role of drugs? Drugs are rarely needed. Antibiotics are not indicated in viral or

uncomplicated bacterial gastroenteritis and may cause harm.

Antidiarrhoeal, antiemetic agents, and antimotility agents are not recommended for routine use because of the risk of adverse effects.

Antibiotics In non-typhoid Salmonella infections antibi

otics increase the risk of prolonged carriage and disease relapse.

Treating gastroenteritis due to Shiga toxin producing E coli with antibiotics may increase the risk of haemolytic uraemic syndrome.

Antibiotics are required, however, for bacterial gastroenteritis complicated by septicemia and in cholera, shigellosis, amoebiasis, giardiasis, and enteric fever.

Zinc supplement In developing countries, oral zinc given at t

he onset of symptoms decreases the duration and severity of acute diarrhea and is recommended by the WHO and UNICEF.

The dosage and course of treatment ＜ 6m ： zinc element 10mg ； ＞ 6m ： zinc element 20mg ， Course: 10-14d

Vitamin A does not influence the course of acute gastroenteritis.

Can gastroenteritis be prevented?

Environmental sources, such as children’s animal farms, swimming pools, and beaches.

Good hygiene including careful hand washing, nappy disposal, and preparation and storage of food and drinking water.

Hygiene in institutions, including hospitals where nosocomial infection is common.

Oral rotavirus vaccines.

When to refer to paediatric service If diagnosis in doubt Parent or carer unable to manage the child a

t home Gastroenteritis in a young infant (<6 months) High risk of dehydration—worsening diarrhe

a and vomiting with significant fluid loss Severe dehydration or shock Severe abdominal pain, localised tenderness,

or mass

When to refer to paediatric service Evidence of anaemia, thrombocytopenia, p

oor urine output, or hypertension (think haemolytic uraemic syndrome)

Increased risk of complications—underlying disease (such as diabetes), malnutrition, renal failure, high fever

Persistent diarrhea beyond two weeks may indicate complications such as reinfection, lactose intolerance, or underlying bowel disease

Summary

Acute gastroenteritis accounts for millions of deaths each year in young children, mostly in developing communities.

Rotavirus is the most common cause of acute gastroenteritis worldwide.

Dehydration, which may be associated with electrolyte disturbance and metabolic acidosis, is the most frequent and dangerous complication.

Optimal management with oral or intravenous fluids minimises the risk of dehydration and its adverse outcomes.

Most children are not dehydrated and can be managed at home

Dehydration, metabolic acidosis, and electrolyte disturbance can be prevented and treated by fluid therapy

Mild-moderate dehydration can be treated with oral or enteral rehydration using low osmolality oral rehydration solutions (ORS)

Severely dehydrated or shocked children usually need intravenous fluids and hospital admission

Routine use of antibiotics, antidiarrhoeal agents, and antiemetics is not recommended.

General practitioners have an important role in prevention, through encouraging breastfeeding, recommending and advocating free access to rotavirus vaccination, and educating carers about personal and food hygiene.