Download (10%cases) Persistent or chronic diarrhea

Acute Gastroenteritis
Jie Chen , MD ,phD
Children Hospital
Zhe Jiang University
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 is a clinical syndrome of diverse
etiology associated with many influencing
factors
• In pediatrics, diarrhea is defined as an
increase in the
– Fluidity
– Volume
– Frequency
of the stool
Relative to the usual habits of each
individual
Classification of Diarrhea in Infant
• Acute diarrhea:
– Short in duration( less than 2
Gastroenteritis or enteritis
weeks)
Systemic infection
Overfeeding
Antibiotic association
• Persistent or chronic diarrhea:
infection or more
–Post
2 weeks
Secondary dissacaridase deficiency
IBS
Food allergy , et al
Type of diarrhea
• Acute watery diarrhea
– (80% cases)
• Dysentery
– (10%cases)
• Persistent or chronic diarrhea
– (10%cases)
Etiology of Diarrhea
Infective
Viruses
Bacteria
Parasites
Fungi
Non
infective
Food Allergy
Symptomatic
Overfeeding
Intolerance
Climate
Common Infectious Causes of Diarrhea
• Viruses
 Rotavirus
 Astrovirus
 Calicivirus
 Enteric
(including norovirus)
adenovirus (serotypes 40 and 41)
Common Infectious Causes of Diarrhea
• Bacteria
– Campylobacter jejuni
– Escherichia coli
• EPEC; ETEC; EITC; EHEC; 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
• Fungi
– Candida albicans
Epidemiology：Feces—mouth route
Infected Animal
Infected Person
Food
Water
Person
Mechanisms of diarrhea
• Osmotic
• Secretory
• Mucosal inflammation (invasion)
• Motality
Mechanisms of Diarrhea
Osmotic
Defect
Digestive enzyme deficiencies
Ingestion of unabsorbable solute
Example
Viral infection
Lactase deficiency
Sorbitol /magnesium sulfate
Comment
Stop with fasting
No stool WBCs
Mechanisms of Diarrhea
Secretory
Defect
Increased secretion
Decreased absorption
Example
Cholera
Toxinogenic E.coli
Comment
Persists during fasting
No stool leukocytes
Mechanisms of Diarrhea
Invasion
Defect
Inflammation
Decreased colonic reabsorption
Increased motility
Example
Bacterial enteritis
Comment
Blood, mucus and WBCs in stool
Mechanisms of Diarrhea
Increased motility
Defect
Decreased 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
•
•
•
•
•
Campylobacter jejuni
EIEC
Shigella species
Salmonella tymphimurium
Yersinia enterocolitica
(invasion)
Pathogenesis of Rotavirus enteritis
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 functions Impairment of absorptive functions
the transport of water and
discreasing hydrolysis of
electrolytes via glucose and amino
disaccharides
acid co-transporters
Malabsorption of complex
carbohydrates, particularly
An imbalance in intestinal fluid
lactose
absorption to secretion
Other than digested into
monosaccharide, lactose be
lysis into organic acid, hyperosmosis
Watery stool
Pathogenesis of enterotoxinogenic
enteritis
enterotoxigenic
organisms
Ingestion
small bowel mucosa and
proliferate
Heat-stable enterotoxin
Heat-labile enterotoxin
binds to receptors of
epithelial cells
activates
activates
cellular guanylatecyclase
cellular adenylcyclase
increased intracellular
concentrations of cGMP
increased intracellular
concentrations of cAMP
promote the net secretion of water and chloride
decrease absorption of sodium and chloride by villous cells
Watery diarrhea
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 stool may occur in clinical
observation
Pathogenesis of invasive enteritis
Invasive Ingestion
enteropathogen
Gut lumen
Colon 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
Clinical manifestation
 Gastrointestinal
 Systemic
symptom
symptom
 Dehydration
and electrolyte
disturbances
 Dehydration
 Hypokalemia
 Metabolic Acidosis
 Hypocalcemia
/Hypomagnesemia
Dehydration
• Excessive loss of water,
• especially loss of extracellular fluid
Degree of dehydration
Dehydration
Mild
Moderate
Severe
Decrease in
body weight
3% ～ 5％
5～10％
10％ ～15%
(50ml / kg)
(50～100ml / kg)
(100～120ml / kg)
Mental
Well, alert
Irritable/Restless
/thirsty
Lethargic/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
Normal
Tachycardia little
Hypotension
Tachycardia with
weak pulse
≥ 3 seconds
Blood pressure
heart rate
Pulse
Capillary refill
Normal
≤ 2 seconds
Type of dehydration
Isotonic
(isonatremic)
Hypertonic
(hypernatremic)
Hypotonic
(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 Acidosis
• Pathogeny
– lose of large amount of basic substances from
gastrointestinal tract
– too much acid metabolite
• Blood gas analysis
pH nomarl
pH
HCO3HCO3-
CO2
CO2
• Degree
– Mild
– Moderate
– Severe
HCO3- 18~13 mmol / L
HCO3- 13~9 mmol / L
HCO3- <9
mmol / L
hypokelemia
• Pathogeny
– Lake of intake
– Loss of potassium from gastrointestinal
tract
• Blood electrolytes analysis
– K+ < 3.5 mmol/L
Hypokelema
• 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 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
Diarrhea?
Infective
Persisting or
chronic diarrhea
Acute stage
Watery, loose stools
without or only a
minute amount of
WBC
Epidemic data
Stool culture
Serous assay
Virus
ETEC
EPEC
WBC and RBC,
mucus in stools
Antibiotic
associate
diarrhea
Persisting
infection?
Stool culture
Serous assay
Shigella
EIEC
CJ
Salmonella
Yersinia
Entamoeba
histolytic
Giardia lamblia
Cryptosporidium
Staphylo
CD
Candida
Non-infective
Allergic state? Symptomatic diarrhea? Inappropriate feeding?
food intolerance Lack of disaccharidase? Immunodeficience?
Malnutrition? Malabsorption ? etc.
Treatment
• 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 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 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 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
ORS composition
 Sodium Chloride
 Tri-Sodium Citrate (bicarbonate)
 Potassium Chloride
 Glucose
Type 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
• 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 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
Given over the first 8 hrs
• 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 next 16 hrs
Antibiotic Therapy
Organisms
Antibiotic
Campylobacter
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
Organisms
Antibiotic
Shigella
species
Third-generation cephalosporin
Salmonella
Usually none (if ≥ 3 months old) for non
typhoid;
Ampicillin, TMP-SMZ†,
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
Antibiotic Therapy
Organisms
Antibiotic
E. histocolytica
metronidazole followed by a luminal agent,
such as iodoquinol
G. lamblia
Albendazole
Metronidazole
Furazolidone
Quinacrine
Cryptospodium
Non specific treatment
Complication _watery diarrhea
• Hypovolemic shock
• Tetany & Convulsions
• Hypoglycemia
• Renal failure
Complication _dysentery
•
•
•
•
•
•
Toxic encephalopathy
Hemolytic uremic syndrome (HUS)
Intestinal abcess
Protein losing enteropathy
Arthritis
Perforation
Prognosis
Mortality
Dehydration
Malnutrition
Global Impact of Enteric Disease Deaths
in young children
Average of 2.2 million deaths per year worldwide
Cholera
120 000
Typhoid
600 000
ETEC
380 000
Rotavirus
450 000
Shigella
670 000
WHO, 2000
Prevention
• Safe drinking water and food
– “Boil it, cook it, peel it, or forget it. "
• Hand washing
• Proper sanitation
• Vaccines