2Definition Acute inflammation of the lining of the stomach and intestines caused by viruses, bacteria or their toxins and parasites.Presents commonly with diarrhea, abdominal cramps and vomiting.Common complaint in the ERAlso significant cause of mortality in under-developed countriesPerson to person spread or ingestion of contaminated food or waterDiarrhea : daily stools with mass > 15g/kg for children <2> 200g for children 2 +
7Rota virus Faeco – oral transmission 6 – 24 months of age Sudden onset watery diarrhea and vomiting with little abdominal painSelf limiting in healthy individuals1 – 6 day durationSeasonal - temperate climates: “winter gastro”- tropical climates: summer peakTreatment : symptomatic
8Norwalk agent “Epidemics” of diarrhea in communities Closed / semi closed communitiesSchool - age children , family contacts and adults affectedDiarrhea, nausea and abdominal crampsVomiting not prominentSelf limiting 24 – 48 hoursTreatment : supportive
9Viral Gastroenteritis SummarySelf limitingUsually no bloody stoolsMild to moderate dehydrationGenerally not toxicUsually amenable to oral rehydration and/or overnight admission
11PathogenesisInvasion with mucosal ulceration and activation of inflammatory cascade, formation of abscessese.g. Campylobacter, Salmonella, ShigellaGeneration of toxinse.g Staphylococcal food poisoningShigella toxinCombination of above
12Bacterial gastroenteritis ± Bloody diarrheaChild appears systemically ill : sepsisGreater degree of dehydrationAbdominal painRaised inflammatory markersStool culture will show leucocytes> 5 /hpfExtra abdominal organ involvement :Bacteremia osteomyelitis- meningitis- endocarditis
13Common pathogens Campylobacter Salmonella Shigella Yersinia Pathogenic E.coliCause 10 – 15 % of diarrheal illnessUnder developed nations consider vibrio species
14Salmonella Food borne outbreaks in summer Incubation 8 – 48 hrs Abdominal cramps / nauseaMay/may not have bloody stoolsWhite cell count marginally raisedStool methylene blue staining shows polymorphonuclear lymphocytesRectal swab positive in most casesComplications - dehydration- dissemination - osteomyelitis- meningitis- endocarditis
15Enteric fever Dissemination of certain salmonella S.typhi typhoid feverChills and fever, 40deg +Relative bradycardiaSplenomegalyMacular rashLeucopenia
16Shigella Swimming pools, water borne, travel ASx – mild gastroenteritis – bacillary dysentryBacillary dysentry- profound inflammatory Rx- fever , abdominal pain , SICK !- diffusely tender abdomen, not peritonitic- mucoid/bloody stools, tenesmus- toxin production causes CNS irritation- sheets of neutrophils with methylene blue stainComplications : dehydration, seizures, colonic perf.
17E.coli Type of illness depends on viro type Enterohemorrhagic (EHEC) – HUS, haemorrhagic colitisEnteroaggregative (EAEC ) – persistent diarrhea inunderdeveloped countriesEnteropathogenic (EPEC) – leading cause of infantilediarrhea in africaEnteroinvasive (EIEC ) - similar to shigella dysentry
19Cholera Water born Unsanitary conditions Toxin producing V.cholera Heat labile enterotoxin causes inhibition of Na+ reabsorbtion through adenyl cyclase activationIncubation 24 – 72 hoursSeverity of symptoms depends on “dose” of organismsWatery brown diarrhea becoming pale ( rice water )Fluid loss can be MASSIVE
20Approach to Gastroenteritis NB MANY sick children present with “gastro”Convenient diagnosis !!HistoryGeneral examination: How sick is the child ? Hydration/nutritional stateSystem examination: exclude co- existing / underlying pathologyConsider differential diagnosis.
21Risk factors for dehydration Unable to consume water independentlyUnable to regulate temperature effectivelyLarge surface area in relation to weightLarger evaporative losses- tachypnea- crying / tears
22Dehydration Volume depletion - contraction of total IV plasma pool Dehydration – loss of plasma-free water disproportionate to loss ofsodiumIsonatremic volume depletion :most common in “dehydrated” children --- VOLUME DEPLETIONNa and H20 lost in proportionate quantitiesExcessive extrinsic loss of fluidsHyponatremic volume depletionVolume depletion with hyponatremiaPlasma volume contraction with free water excesse.g child with diarrhea given tap water to replenish lossesHypernatremic volume depletionVolume depletion + dehydrationPlasma volume contraction + free water loss
23Electrolytes 1 Hypernatremia : Na > 145meq/L Causes : - Water loss > electrolyte loss e.g. diarrhea- Pure water depletion-Sodium excess – improper mixing of formulaPlasma tonicity increases ……. Cellular dehydrationComplications – cerebral hemorrhage, seizures,paralysis, encephalopathyClinically : abdominal wall skin doughyHyponatremia Na < 135meq/L- supplementation of fluid losses with hypotonic fluids- loss from GI tractPlasma tonicity decreases …….. Cellular oedemaComplications - cerebral oedemaClinically : tenting of skin on abdominal wall
24Electrolytes 2 Potassium Serum potassium may not reflect true potassiumUsually potassium depletion, initially not significantConsider as part of replacement fluids when adequate urine output obtainedAcidosisBicarbonate loss in stoolsDecreased renal perfusion – less acids excretedDecreased tissue perfusion – lactic acid production
25Parameters of dehydration 3-5% % >10%Mental status N ill , not toxic lethargicHeart rate N or up tachycardia marked tachyPulse quality N N or down poor qualityRespiratory Rate N tachypnoea acidoticCapillary refill N <2s – 4s > 4sPerfusion warm cool cool, mottledBlood pressure N N hypotensiveEyes N slightly sunken very sunkenTears N decreased absentMucous membranes moist sticky drySkin turgor recoil delayed markedly delayedUrine output N to down down minimal
26ORS Vomiting not contraindication Rehydration modality of choice EXCEPT – Severe volume loss/shock- lethargy- electrolyte problems- significant co existing/underlying illness- acute abdomen/ obstruction- clinical judgment dictates otherwiseEstimate severityMild: ml/kgModerate 80ml/kg25% volume given each hour for 4 hours and reassess.
27Failure of ORS Inability/unwillingness to ingest fluid Ongoing losses exceeding rate of replenishmentPoor techniquePoor motivation i.e. “ fed up” parentProblem of ongoing vomiting ?- continue with small volumes frequentlyNasogastric tube an option : continuous administration of ORSVomiting not a contraindicationSafe and efficient alternative
28Resuscitation Emergency resuscitation phase Re – expansion of intravascular spaceIso tonic crystalloid – 0.9%NaCl @ 20ml/kg over 20 minutesRingersPlasmalyteReassess after each bolusRepeat up to 60ml/kgNo improvement ? Reassess for other pathology e.g septic shockNB NB check glucose !!!!
29Replacement phase Existing deficit %dehydration x body weight x 10 = ml50% given over first 8 hours, the rest over next 16hrs+Maintenance fluidsCalculation :100ml/kg first 10 kg50ml/kg next 10kg25ml/kg for each kg above 20kgGive fluids as 0.45%NaCl + 5% dextroseAdd 10mmol KCl to each 500 mlNB . Ongoing losses !!!!!NB ½ darrows contains K
30Electrolytes Acidosis Assess on blood gas Bicarbonate supplement : 1/3 x base deficit x body weightHyponatremiaTreat if Na < 125Calculate Na deficit = (Desired Na – Measured Na) x 0.6 x kgSafe rate of change = 12mmol/L rise / dayHypernatremiapure free water deficitCalculate [(Na – 145) /2]x [4ml/kg] x wt (kg)Safe rate of change = 12mmol/L decline/day
31Role of drugsAntibiotics not indicated in viral or uncomplicated bacterial GastroenteritisMay cause more harm than goode.g. prolonging carrier state of some Salmonella infectionspotentiation of toxin production by pathogenic e.coliAntibiotics are indicated in> gastroenteritis complicated by septicemia> cholera, shigellosis, enteric fever, amoebiasis, giardiasisNO antiemetics / anti motility agentsOral zinc given in developing countries decreases duration of symptoms
32Don’t get caught out !!>Vomiting only – always consider another diagnosise.g. poisoning , intestinal obstruction, appendicitis, intussusseption and metabolic causes>Children <3 mo rarely get “gastro”>Urinary tract infections , URTI’s,LRTI’s can present as “gastro”