acute gastroenteritis

Acute GastroenteritisAcute Gastroenteritis

Jie Chen , MD ,phD

Children Hospital

Zhe Jiang University

教学目标教学目标

1. 掌握小儿腹泻病的病因分类及临床表现；

2. 掌握小儿腹泻病的诊断和治疗原则

Diarrhea Diarrhea

Diarrhea is a clinical syndrome of diverse etiology associated with many influencing factors

• In pediatrics, diarrhea is defined as an increase in the– Fluidity– Volume of the stool – Frequency

Relative to the usual habits of each individual

Classification of Diarrhea in InfantClassification of Diarrhea in Infant

• Acute diarrhea:

– Short in duration( less than 2 weeks)

• Persistent or chronic diarrhea:

– 2 weeks or more

Gastroenteritis or enteritis

Systemic infection

Overfeeding

Antibiotic association

Post infectionSecondary dissacaridase deficiencyIBSFood allergy , et al

Type of diarrheaType of diarrhea

• Acute watery diarrhea – (80% cases)

• Dysentery – (10%cases)

• Persistent or chronic diarrhea– (10%cases)

Infective Non infective

Viruses Bacteria Parasites

Fungi

Food Allergy

Symptomatic

Overfeeding

Intolerance

Climate

Etiology of DiarrheaEtiology of Diarrhea

Common Infectious Causes of Diarrhea Common Infectious Causes of Diarrhea

• Viruses Rotavirus

Astrovirus

Calicivirus (including norovirus)

Enteric adenovirus (serotypes 40 and 41)


• Bacteria – Campylobacter jejuni – Escherichia coli

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


• Parasites

– Entamoeba histolytica (ambiasis)

– Giardia lamblia

– Cruptosporidium parvum

• Fungi

– Candida albicans

EpidemiologyEpidemiology ：： FecesFeces——mouthmouth routeroute

WaterFood

Infected Animal

Infected Person

Person

Mechanisms of diarrheaMechanisms of diarrhea

• Osmotic

• Secretory

• Mucosal inflammation (invasion)

• Motality

Mechanisms of DiarrheaMechanisms of Diarrhea

OsmoticDefect

Digestive enzyme deficiencies

Ingestion of unabsorbable solute

ExampleViral infection

Lactase deficiency

Sorbitol /magnesium sulfate

CommentStop with fasting

No stool WBCs


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


InvasionDefect

InflammationDecreased colonic reabsorptionIncreased motility

ExampleBacterial enteritis

CommentBlood, mucus and WBCs in stool


Increased motility

DefectDecreased transit time

Example:

Irritable bowel syndrome

Common infectious causes of diarrhea Common infectious causes of diarrhea and their virulent mechanismand 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

Rotaviruses attach and replicate in the mature enterocytes at the tips of small intestinal villi

Destroy villus tip cells, variable degrees of villus blunting mononuclear inflammatory infiltrate in the lamina propria

Impairment of digestive functionsdiscreasing hydrolysis of disaccharides

Impairment of absorptive functionsthe transport of water and electrolytes via glucose and amino acid co-transporters

An imbalance in intestinal fluid absorption to secretion

Malabsorption of complex carbohydrates, particularly lactose

Other than digested into monosaccharide, lactose be lysis into organic acid, hyper-osmosis Watery stool

Pathogenesis of Rotavirus enteritisPathogenesis of Rotavirus enteritis

enterotoxigenic organisms

Ingestion small bowel mucosa and proliferate

activates cellular guanylatecyclase

Heat-stable enterotoxin

promote the net secretion of water and chloride

increased intracellular concentrations of cAMP

activates cellular adenylcyclase

binds to receptors of epithelial cells

Heat-labile enterotoxin

decrease absorption of sodium and chloride by villous cells

increased intracellular concentrations of cGMP

Watery diarrhea

Pathogenesis of enterotoxinogenic Pathogenesis of enterotoxinogenic enteritisenteritis

• 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

Pathogenesis of enterotoxinogenic Pathogenesis of enterotoxinogenic enteritisenteritis

Invasive enteropathogen

Ingestion Gut lumenColon and rectum mucous membrane

proper

Extensive destruction of the epithelial layer Inflammation: Hyperemia, swelling, heavy neutrophil

infiltration, inflammatory exudate

The desquamation, ulceration, and formation of microabscesses in the colonic mucosa inhibit absorption of

water

stools that are frequent and scanty and that contain blood inflammatory cells and mucus

Pathogenesis of invasive enteritisPathogenesis of invasive enteritis

Clinical manifestationClinical manifestation

Gastrointestinal symptom

Systemic symptom

Dehydration and electrolyte disturbancesDehydration

Hypokalemia

Metabolic Acidosis

Hypocalcemia /Hypomagnesemia

DehydrationDehydration

• Excessive loss of water, • especially loss of extracellular fluid

Degree of dehydrationDegree of dehydration

Dehydration Mild Moderate SevereDecrease in body weight

3% ～ 5 ％(50ml / kg)

5 ～ 10 ％(50 ～ 100ml / kg)

10 ％～ 15%(100 ～ 120ml / kg)

Mental Well, alertIrritable/Restless/

thirstyLethargic/coma

Fontanel/Eye Sunken ± Sunken Severely sunken

Skin turgor Normal ± Decrease Markedly decrease

Mouth+tongue normal sticky Dry

Tears present Decrease Absent

Urine Mild oliguria oliguria Anuria

Blood pressure

heart rate

Pulse

Capillary refill

Normal

Normal

Tachycardia little

≤ 2 seconds

Hypotension

Tachycardia with weak pulse

≥ 3 seconds

Type of dehydrationType of dehydration

Isotonic Isotonic

(isonatremic)(isonatremic)Hypertonic Hypertonic

(hypernatremic)(hypernatremic)Hypotonic Hypotonic

(hyponatremic)(hyponatremic)

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

Metabolic AcidosisMetabolic Acidosis

• Pathogeny– lose of large amount of basic substances from

gastrointestinal tract– too much acid metabolite

• Blood gas analysis pH nomarl HCO3- CO2 pH HCO3- CO2

• Degree– Mild HCO3

- 18~13 mmol / L– Moderate HCO3

- 13~9 mmol / L– Severe HCO3

- <9 mmol / L

hypokelemiahypokelemia

• Pathogeny– Lake of intake– Loss of potassium from gastrointestinal

tract• Blood electrolytes analysis

– K+ < 3.5 mmol/L

HypokelemaHypokelema

• Clinical manifestation– Nervous system

• depressed– Muscle

• inertia of limbs ， muscular tension down ， severely retardant paralysis ， respiratory muscle paralysis

– Heart• heart rate increasing, arrhythmia, Adams －

Stokes syndrome, heart rate decreasing ， atrioventricular block, heart sound lowering,

• Cardiogram– U wave appearing ， U≥T ， flattened T wave,

Laboratory and Imaging StudiesLaboratory and Imaging Studies

• 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 cluture

• 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

Diagnosis & Differential Diagnosis Diagnosis & Differential Diagnosis

Diarrhea?

Watery, loose stools without or only a

minute amount of WBC

Epidemic dataStool cultureSerous assay

Stool cultureSerous assay

Shigella EIEC CJ

Salmonella Yersinia

Virus ETECEPEC

WBC and RBC, mucus in stools

Acute stagePersisting or

chronic diarrhea

Antibiotic associate diarrhea

Infective

Non-infective Allergic state? Symptomatic diarrhea? Inappropriate feeding? food intolerance Lack of disaccharidase? Immunodeficience? Malnutrition? Malabsorption ? etc.

Persisting infection?

Entamoeba histolytic

Giardia lamblia Cryptosporidium

Staphylo CD

Candida

TreatmentTreatment

• Primarily supportive– Fluid therapy

• Rehydration• Correcting acidosis• Potassium supplement • Correcting ongoing loss

– Managing secondary complication resulting from mucosa injury

• Antibiotic treatment – for only some bacterial and parasitic causes of

diarrhea

• Start food as soon as possilble

Fluid Management of DehydrationFluid Management of Dehydration

• Calculate 24-hr water needs

– Calculate maintenance water

– Calculate deficit water

• Calculate 24-hr electrolyte needs

– Calculate maintenance sodium and potassium

– Calculate deficit sodium and potassium

• Select an appropriate fluid (based on total water and electrolyte needs)

– Administer half the calculated fluid during the first 8 hr, first subtracting any boluses from this amount

– Administer the remainder over the next 16 hr

• Replace ongoing losses as they occur

Fluid TherapyFluid Therapy

• Deficit of water and electrolytes– Water Deficit: Percent dehydration × weight

– Sodium Deficit:Water deficit × 80 mEq/L

– Potassium Deficit:Water deficit × 30 mEq/L

• Ongoing loss– After they occur

– Sodium: 55 mEq/L

– Potassium: 25 mEq/L

– Bicarbonate: 15 mEq/L

• Maintenance– 0-10kg 100 mL/kg

– 11-20kg 1000 mL + 50 mL/kg for each 1 kg >10 kg– >20kg 1500 mL + 20 mL/kg for each 1 kg >20 kg*(max 2400mL)

– Sodium ： 2 - 3 mEq/kg/day

– potassium ： 1-2mEq/kg/day

Fluid TherapyFluid Therapy

• ORT– Mild to moderate dehydration from diarrhea

• Intravenous– With severe dehydration

– with uncontrollable vomiting

– unable to drink because of extreme fatigue, stupor, or coma

– with gastric or intestinal distention

Sodium Chloride

Tri-Sodium Citrate (bicarbonate)

Potassium Chloride

Glucose

ORS compositionORS composition

Type of ORSType of ORS

Solution Glu g/L

Na mEq/L

K mEq/L

Cl mEq/L

WHO 20.0 90 20 80

Rehydralyte 20.5 75 20 65

Pedialyte 20.5 45 20 35

Infanlyte 20.0 50 20 40

ORT ORT

• Mild: ORS 50 mL/kg within 4 hours

• Moderate: ORS 100 mL/kg over 4 hours to

• Supplementary ORS is given to replace ongoing

losses

– An additional 10 mL/kg of ORS is given for each

stool

• Breastfeeding should be allowed after rehydration

in infants who are breastfed

• usual formula, milk, or feeding for other patients

should be offered after rehydration

Intravenous treatmentIntravenous treatment

• Restore intravascular volume– Normal saline: 20 mL/kg over 20 min (repeat until

intravascular volume restored)

• Deficit of water and electrolytes– Solution: 5% dextrose in half NS + 20 mEq/L of potassium

chloride

• Ongoing loss– Solution: 5% dextrose in ¼ normal saline + 15 mEq/L

bicarbonate + 25 mEq/L potassium chloride

• Maintenance– Solution: 5% dextrose in ¼ normal saline + 20 mEq/L of

potassium chloride

Given over the first 8 hrs

Given over the next 16 hrs

Organisms AntibioticCampylobacter Jejuni

erythromycin

azithromycin

E. Coli EPEC: Indicated for infants younger than 3

months old with

ETEC: Usually none if endemic

TMP-SMZ or ciprofloxacin for traveler's

diarrhea

EIEC: Third-generation cephalosporin

TMP-SMZ

Ampicillin

EHEC: not recommend

EAEC: TMP-SMZ

Antibiotic Therapy Antibiotic Therapy

Organisms AntibioticShigella species

Third-generation cephalosporin

Ampicillin, TMP-SMZ†,

Salmonella Usually none (if ≥ 3 months old) for non

typhoid;

ampicillin, cefotaxime for S. typhi or

S.paratyphy

Yersinia enterocolitica

None for uncomplicated diarrhea; TMP-

SMZ; gentamicin or cefotaxime for

extraintestinal disease

C. difficile metronidazole,

vancomycin


Organisms AntibioticE. histocolytica metronidazole followed by a luminal agent,

such as iodoquinol

G. lamblia Albendazole

Metronidazole

Furazolidone

Quinacrine

Cryptospodium Non specific treatment


Complication _watery diarrheaComplication _watery diarrhea

• Hypovolemic shock

• Tetany & Convulsions

• Hypoglycemia

• Renal failure

Complication _dysenteryComplication _dysentery

• Toxic encephalopathy

• Hemolytic uremic syndrome (HUS)

• Intestinal abcess

• Protein losing enteropathy

• Arthritis

• Perforation

Dehydration Malnutrition

Mortality

Prognosis Prognosis

Global Impact of Enteric Disease Deaths Global Impact of Enteric Disease Deaths in young childrenin young children

Cholera120 000

ETEC380 000

Typhoid600 000

Average of 2.2 million deaths per year worldwide

Shigella670 000

Rotavirus450 000

WHO, 2000

PreventionPrevention

• Safe drinking water and food

– “Boil it, cook it, peel it, or forget it. "

• Hand washing

• Proper sanitation

• Vaccines

acute gastroenteritis

Documents