Pediatrics

DEFINITION

Diarrhoea is the passage of 3 or more loose or watery stools in a 24-hour period (or a change from the normal pattern that the mother considers abnormal). Acute diarrhoea lasts < 14 days. It is a leading cause of under-5 mortality in India, chiefly through dehydration and its consequences.

ETIOLOGY

• Viral (commonest): Rotavirus (the leading cause of severe dehydrating diarrhoea in infants), norovirus, adenovirus.
• Bacterial: enterotoxigenic E. coli (ETEC), Shigella (dysentery), Vibrio cholerae (rice-water stools), Salmonella, Campylobacter.
• Parasitic: Giardia lamblia, Entamoeba histolytica, Cryptosporidium.
• Non-infective: antibiotic-associated, feeding errors, food allergy, malabsorption.

PATHOPHYSIOLOGY (mechanisms)

• Secretory — enterotoxins (e.g. cholera toxin) activate cAMP → active Cl⁻ and water secretion → voluminous watery stools that persist with fasting.
• Osmotic — unabsorbed solutes (e.g. lactose in disaccharidase deficiency) draw water into the lumen; stops with fasting.
• Invasive/inflammatory — mucosal invasion (Shigella, Entamoeba) → blood, mucus and pus in stool (dysentery).

ASSESSMENT OF DEHYDRATION (WHO)

The single most important step is to assess the degree of dehydration, which then guides the treatment plan:

TREATMENT — PLAN A (No dehydration; home treatment)

The '4 rules of home treatment':

• Give extra fluids — ORS and home fluids (rice water, buttermilk, soup, plain water) after each stool; ~50–100 mL (< 2 yr) or 100–200 mL (≥ 2 yr) per loose stool.
• Give zinc — 20 mg/day (> 6 months) or 10 mg/day (< 6 months) for 14 days.
• Continue feeding — breastfeeding and age-appropriate food (do NOT starve the gut).
• When to return — teach danger signs: blood in stool, repeated vomiting, poor drinking, fever, or no improvement in 3 days.

TREATMENT — PLAN B (Some dehydration; ORS in clinic)

• Give ORS 75 mL/kg over 4 hours (or ~weight × 75) under supervision; give by spoon/cup frequently.
• Reassess after 4 hours — if improved → Plan A; if still 'some dehydration' → repeat Plan B; if worsened → Plan C.
• Continue breastfeeding; add zinc; if the child wants more ORS, give more.

TREATMENT — PLAN C (Severe dehydration; IV fluids)

Start IV Ringer lactate (or normal saline) immediately — total 100 mL/kg:

• Reassess every 15–30 min; if not improving, give fluids faster.
• Start ORS (~5 mL/kg/hr) as soon as the child can drink; give zinc when feeding resumes.
• If IV access is impossible → ORS by nasogastric tube (20 mL/kg/hr).

COMPLICATIONS

• Dehydration → hypovolaemic shock, acute kidney injury, and death.
• Electrolyte disturbances — hypo/hypernatraemia, hypokalaemia (ileus, weakness), acidosis.
• Persistent diarrhoea; malnutrition; secondary lactose intolerance; seizures (dysnatraemias).

PREVENTION

• Exclusive breastfeeding; safe complementary feeding; hand-washing and safe drinking water & sanitation.
• Rotavirus vaccine and measles vaccine; vitamin A; use of ORS + zinc at community level.

CLINICAL FEATURES

• Frequent loose/watery stools with or without vomiting; the history should note the number, volume and character (watery vs bloody) of stools and vomits.
• Features of dehydration — irritability or lethargy, sunken eyes, dry mouth, reduced urine output, thirst.
• Fever, abdominal pain and, in dysentery, blood/mucus in the stool with tenesmus.
• Signs of associated problems — malnutrition, respiratory infection, or systemic sepsis.

INVESTIGATIONS (usually clinical; tests only if indicated)

• Most acute watery diarrhoea needs no investigation — assessment of hydration is clinical.
• Stool examination (microscopy/culture) if the stool is bloody, in suspected cholera, in persistent diarrhoea, or in an immunocompromised child.
• Serum electrolytes, blood glucose & renal function in severe dehydration, altered sensorium, convulsions, or before/during IV therapy.
• Blood counts and a septic screen if systemic infection is suspected.

• Diarrhoea = ≥ 3 loose stools/day; assess dehydration first.
• Categories: no / some / severe dehydration (WHO) → Plans A / B / C.
• Plan A: extra fluids + zinc 14 days + continue feeding + when to return.
• Plan B: ORS 75 mL/kg over 4 h; Plan C: IV Ringer lactate 100 mL/kg.
• Rotavirus is the commonest cause; most acute diarrhoea is viral & self-limiting.

• Assessing the DEGREE of dehydration (no/some/severe) is the single key step.
• No dehydration → Plan A; some → Plan B (ORS 75 mL/kg/4 h); severe → Plan C (IV RL).
• Continue feeding/breastfeeding throughout; never withhold food.
• Give zinc for 14 days and avoid anti-diarrhoeals; antibiotics only for dysentery/cholera.
• Prevent with breastfeeding, hygiene, safe water, rotavirus & measles vaccines.

DEFINITION

Oral Rehydration Therapy (ORT) is the administration of fluid by mouth to prevent or correct the dehydration caused by diarrhoea. Oral Rehydration Solution (ORS) is the specially formulated glucose-electrolyte solution used for this purpose. ORT has been described as 'potentially the most important medical advance of the 20th century' for its impact on child survival.

SCIENTIFIC BASIS — Sodium-Glucose Co-transport

The intestinal mucosa has a sodium-glucose co-transporter (SGLT-1) that absorbs sodium and glucose together in a 1:1 ratio, dragging water with them. This transporter remains intact even in secretory diarrhoea (e.g. cholera), which is why oral glucose-salt solutions can rehydrate a child whose gut is actively secreting fluid.

COMPOSITION OF WHO LOW-OSMOLARITY ORS (2002)

WHY LOW-OSMOLARITY ORS? (its advantages)

The older 'standard' ORS was 311 mOsm/L. The reduced-osmolarity (245) formula is now recommended because, compared with the old solution, it:

• Reduces stool output by ~20%.
• Reduces vomiting by ~30%.
• Reduces the need for unscheduled IV fluids by ~33%.
• Is effective for both children and adults, and for cholera as well as other diarrhoeas.

HOW TO GIVE ORS

• Dissolve one packet in 1 litre of clean water; discard after 24 hours.
• Give frequently in small sips by spoon or cup (not by bottle); if the child vomits, wait 10 minutes and continue more slowly.
• Amounts follow the WHO plans — Plan A (after each stool) or Plan B (75 mL/kg over 4 hours).
• Continue breastfeeding and feeding alongside ORS.

HOME-AVAILABLE FLUIDS (when ORS packets are unavailable)

• Salt-and-sugar solution (a pinch of salt + a fistful/scoop of sugar in a glass of water), rice-based ORS (kanji), buttermilk, coconut water, soups.
• Cereal-based ORS (rice-ORS) is especially useful in cholera as it further reduces stool volume.

ADVANTAGES OF ORT

• Simple, cheap, safe and effective; can be given at home by mothers.
• Avoids the risks, cost and skill needs of IV therapy; can be scaled up in the community.
• Physiological — corrects dehydration, acidosis and potassium loss together.

FAILURE / LIMITATIONS OF ORT

• Contraindications: severe dehydration with shock, altered sensorium / inability to drink, ileus/abdominal distension, and very high purging (stool > 10 mL/kg/hr).
• Persistent vomiting despite slow administration → consider nasogastric ORS or IV fluids.
• These situations require initial IV therapy (Plan C), switching to ORS once the child can drink.

EVOLUTION OF ORS

• The original WHO ORS (1975) had an osmolarity of 311 mOsm/L and was designed mainly for cholera in adults.
• Because it caused a slightly high stool output in children with non-cholera diarrhoea, it was replaced in 2002 by the reduced (low)-osmolarity ORS (245 mOsm/L), which is now the universal standard for all ages.

STANDARD vs LOW-OSMOLARITY ORS

USE IN SPECIAL SITUATIONS

• Cholera — ORS works well; a rice/cereal-based ORS further reduces stool volume.
• Severe acute malnutrition — use ReSoMal (lower sodium, higher potassium) instead of standard ORS.
• Hypernatraemic dehydration — ORS is safe and preferred, as it corrects sodium gradually.

'SUPER ORS' (cereal / amino-acid based)

Polymer (rice/cereal)-based ORS provides glucose polymers that are digested gradually, adding more co-transport substrate without raising osmolarity — reducing stool output, especially in cholera.

MONITORING THE RESPONSE

• Reassess hydration, urine output and ongoing stool losses regularly.
• Watch for signs of over-hydration (puffy eyelids) → pause ORS and give plain water/breast milk.
• Escalate to IV fluids if there is persistent vomiting, worsening dehydration, or the child cannot drink.

• ORS works via sodium-glucose co-transport (intact even in cholera).
• Low-osmolarity ORS = 245 mOsm/L (Na 75, glucose 75, K 20, citrate 10).
• Reduces stool output, vomiting and need for IV vs old ORS.
• Give by cup/spoon; ORS treats dehydration, not the diarrhoea.
• Always add zinc for 14 days and continue feeding.

• ORS rehydrates via intact sodium-glucose co-transport, even in cholera.
• Low-osmolarity ORS (245) beats the old formula (less stool, vomiting, IV need).
• Give small frequent sips by cup; discard after 24 hours.
• ORS corrects dehydration but does NOT stop the diarrhoea — always add zinc.
• Use ReSoMal (not standard ORS) in severe acute malnutrition.

DEFINITION

Persistent diarrhoea is an episode of diarrhoea, presumed to be of infectious origin, that starts acutely but lasts for 14 days or more. It must be distinguished from chronic diarrhoea (≥ 14 days but usually of a non-infectious, often congenital cause). Persistent diarrhoea carries a high risk of malnutrition and death.

RISK FACTORS

• Young age (< 6 months) and malnutrition (a bidirectional relationship).
• Recent acute diarrhoea; lack of breastfeeding; artificial/animal-milk feeding.
• Recent measles; immunodeficiency (including HIV); previous inappropriate antibiotic use.
• Micronutrient deficiency (zinc, vitamin A).

PATHOPHYSIOLOGY

• Persistent mucosal injury → villous atrophy → reduced absorptive surface and loss of brush-border enzymes.
• Secondary lactose (disaccharidase) deficiency → osmotic diarrhoea on milk feeds.
• Cow's-milk / soy protein sensitivity and small-bowel bacterial overgrowth.
• A vicious cycle of infection → mucosal damage → malabsorption → malnutrition → impaired mucosal repair & immunity → continued diarrhoea.

CAUSES

• Persistent/sequential enteric infection (E. coli, Shigella, Salmonella, Cryptosporidium, Giardia).
• Post-enteritis lactose intolerance and cow-milk protein intolerance.
• Underlying malnutrition and micronutrient deficiency.

CLINICAL EVALUATION

• Assess hydration and nutritional status (weight, oedema, MUAC) — the two priorities.
• History — duration, stool character (watery vs bloody), feeds (milk relation), prior antibiotics, associated infections.
• Look for systemic infection (pneumonia, UTI, sepsis, TB) and signs of specific deficiencies.

INVESTIGATIONS

• Stool — microscopy (ova, cysts, pus cells, RBCs), reducing substances & pH (low pH + positive reducing substances = lactose intolerance), culture.
• Blood — CBC, electrolytes, blood glucose; screen for HIV and systemic infection.
• Assess for associated deficiencies (zinc, vitamin A).

MANAGEMENT — Principles

• Treat & prevent dehydration — ORS (some/severe dehydration by Plans B/C); most children have no dehydration.
• Nutritional management is the cornerstone:

• Continue breastfeeding.
• Reduce the lactose load — replace animal milk with yoghurt/curd or a low-lactose diet; give energy-dense, frequent, mixed cereal-based feeds.
• Provide adequate calories (~150 kcal/kg/day) for catch-up; a lactose-free/milk-free diet only if the above fails.

• Micronutrients — zinc for 14 days, plus vitamin A, folate, copper and multivitamins.
• Antibiotics only for identified pathogens / dysentery / associated systemic infection (not routine).
• Treat associated infections (pneumonia, UTI, sepsis).

COMPLICATIONS

• Progressive malnutrition and growth faltering; recurrent dehydration.
• Electrolyte disturbances; sepsis; and increased mortality.

PREVENTION

• Exclusive breastfeeding; appropriate complementary feeding; avoid unnecessary antibiotics in acute diarrhoea.
• Zinc supplementation, measles & rotavirus immunisation, vitamin A, and good hygiene/sanitation.

CLINICAL FEATURES

• Prolonged (≥ 14 days) loose stools, often with a relation to milk feeds (suggesting lactose intolerance).
• Weight loss / growth faltering and features of malnutrition and micronutrient deficiency.
• Recurrent dehydration; perianal excoriation (from acidic, sugary stools); and features of any underlying infection.

STEP-WISE DIETARY MANAGEMENT (the cornerstone)

FOLLOW-UP & MONITORING

• Monitor weight gain, stool frequency and hydration daily during treatment.
• A successful diet produces reducing stool frequency and steady weight gain within a few days.
• Ensure completion of zinc (14 days) and vitamin A; catch-up nutrition after recovery.

WHEN TO REFER / INVESTIGATE FURTHER

• Failure to respond to standard dietary management; severe malnutrition with complications.
• Suspected specific cause — coeliac disease, immunodeficiency/HIV, congenital diarrhoea, or IBD.

MICRONUTRIENT & MINERAL SUPPLEMENTATION

• Give double the RDA of vitamins & minerals for 2 weeks — including folate, vitamin A, copper and magnesium.
• Zinc for 14 days is essential (it restores the gut mucosa and reduces relapse).
• Treat iron-deficiency anaemia during the recovery phase.

CRITERIA FOR HOSPITAL ADMISSION

• Severe dehydration or inability to feed; systemic infection (sepsis, pneumonia).
• Severe acute malnutrition; young infant (< 4 months); failure of home/OPD management.
• Any danger sign — lethargy, high fever, persistent vomiting, convulsions.

• Zinc 20 mg/day (> 6 mo) or 10 mg/day (< 6 mo) × 14 days.
• Micronutrients — double the RDA of vitamins/minerals for 2 weeks; vitamin A age-based.
• Antibiotics only for a proven pathogen/systemic infection.

• Persistent diarrhoea = ≥ 14 days; high risk of malnutrition.
• Causes: secondary lactose intolerance, cow-milk sensitivity, persistent infection.
• Nutritional management is the cornerstone (continue breastfeeding, reduce lactose).
• Give zinc + micronutrients; antibiotics only for a specific pathogen.
• Admit if severe dehydration, systemic infection, SAM, or age < 4 mo.

• Distinguish persistent (≥14 d, infective) from chronic (often congenital) diarrhoea.
• Nutrition is the cornerstone — continue breastfeeding, reduce the lactose load.
• Give zinc + double-RDA micronutrients for 2 weeks.
• Antibiotics only for a proven pathogen or systemic infection.
• Admit young infants, SAM, severe dehydration or treatment failures.

INTRODUCTION

Fluid therapy in a sick child aims to provide the maintenance requirement, replace any existing deficit (dehydration), and cover ongoing (continuing) losses. Children are more vulnerable to fluid imbalance than adults because of a higher body-water content, larger surface area and higher metabolic/turnover rate.

BODY WATER COMPARTMENTS

• Total body water is higher in children (~75% in a newborn, ~60% in an adult).
• Distributed as intracellular fluid (ICF) and extracellular fluid (ECF = interstitial + plasma).
• Infants have a proportionately larger ECF, making them more prone to rapid dehydration.

1. MAINTENANCE FLUID — Holliday-Segar Method

Maintenance replaces normal daily insensible and urinary losses. The Holliday-Segar formula (per 24 hours):

Hourly ('4-2-1') rule: 4 mL/kg/hr for the first 10 kg + 2 mL/kg/hr for the next 10 kg + 1 mL/kg/hr for each kg above 20 kg. Example: a 25 kg child = 1000 + 500 + 100 = 1600 mL/day.

2. DEFICIT THERAPY (correcting dehydration)

• Estimate the deficit from the degree of dehydration — 5% (some) or 10% (severe) of body weight (1% = 10 mL/kg).
• For severe dehydration → WHO Plan C (Ringer lactate 100 mL/kg as 30 + 70 mL/kg).
• Replace the calculated deficit plus maintenance plus ongoing losses; reassess frequently.

3. ONGOING LOSSES

Replace continuing losses (diarrhoea, vomiting, drains, ileostomy) volume-for-volume with an appropriate fluid (e.g. ORS or Ringer lactate for stool losses).

TYPES OF IV FLUIDS

MANAGEMENT OF SHOCK (hypovolaemic)

• Rapid bolus of 20 mL/kg of Ringer lactate / normal saline over 15–20 min; repeat up to 40–60 mL/kg while reassessing.
• In severe malnutrition, fluids are given more cautiously (risk of heart failure) — smaller volumes with close monitoring.
• Add inotropes for fluid-refractory shock; treat the underlying cause (sepsis).

MONITORING

• Vitals, capillary refill, urine output (aim > 1 mL/kg/hr), daily weight, and level of consciousness.
• Serial electrolytes, blood glucose and acid-base status.
• Watch for over-hydration (puffiness, raised JVP, crepitations) and correct sodium disturbances at a safe rate.

WORKED EXAMPLES

• Maintenance — a 16 kg child: (10 × 100) + (6 × 50) = 1300 mL/day (≈ 54 mL/hr).
• Deficit — an 8 kg infant with 10% (severe) dehydration: deficit = 10% × 8 kg = 800 mL, replaced with WHO Plan C (Ringer lactate 100 mL/kg = 800 mL as 30 + 70 mL/kg).
• Total = maintenance + deficit + ongoing stool losses, reassessed frequently.

ESTIMATING THE DEFICIT

SPECIAL SITUATIONS

• Severe malnutrition — give fluids cautiously (use ReSoMal orally; IV only for shock) because of the risk of heart failure.
• Diabetic ketoacidosis — slow, careful rehydration over 48 h to avoid cerebral oedema.
• Shock — rapid isotonic boluses (20 mL/kg) take priority over deficit calculations.

COMMON ERRORS TO AVOID

• Using hypotonic maintenance fluids in sick children → hospital-acquired hyponatraemia.
• Rapid correction of chronic dysnatraemias; and adding potassium before urine output is established.

DAILY ELECTROLYTE & GLUCOSE REQUIREMENTS

PRACTICAL POINT

In practice, maintenance is written as a specific fluid at a calculated hourly rate — e.g. isotonic saline with 5% dextrose and added KCl — reassessing the child clinically at least every few hours and adjusting for ongoing losses.

• Maintenance (Holliday-Segar): 100/50/20 mL/kg for first/next/subsequent 10 kg.
• Hourly '4-2-1' rule; Na 2–3, K 1–2 mmol/kg/day.
• Deficit: 1% dehydration = 10 mL/kg; severe = 100 mL/kg (Plan C).
• Ringer lactate for resuscitation; shock → 20 mL/kg boluses.
• Correct dysnatraemias slowly (≤ 10–12 mmol/L/day).

• Total fluid = maintenance + deficit + ongoing losses, reassessed frequently.
• Holliday-Segar (100/50/20) for maintenance; deficit from the dehydration %.
• Ringer lactate for resuscitation; shock → 20 mL/kg boluses.
• Add potassium only after urine flows; use isotonic maintenance to avoid hyponatraemia.
• Correct sodium slowly (≤ 10–12 mmol/L/day) in dysnatraemias.

DEFINITION

Dysentery is diarrhoea with visible blood (and often mucus) in the stool, reflecting invasion and inflammation of the colonic mucosa. Unlike acute watery diarrhoea (a fluid-loss problem), dysentery is primarily an invasive mucosal infection and carries a risk of serious complications.

ETIOLOGY

• Shigella — the commonest and most important cause of acute bacillary dysentery (S. flexneri, S. dysenteriae).
• Other bacteria — enteroinvasive/enterohaemorrhagic E. coli (EHEC), Campylobacter, Salmonella, Yersinia.
• Entamoeba histolytica — amoebic dysentery (more insidious).
• Non-infective — intussusception, Meckel's diverticulum, IBD (consider if atypical).

BACILLARY vs AMOEBIC DYSENTERY

CLINICAL FEATURES

• Frequent, small-volume bloody-mucoid stools with tenesmus and cramping abdominal pain.
• Fever (often high), anorexia, and rapid weight loss.
• Shigella can cause convulsions, altered sensorium and rectal prolapse, especially in young children.

INVESTIGATIONS

• Stool microscopy — pus cells, RBCs, and amoebic trophozoites (with ingested RBCs) if amoebiasis.
• Stool culture & sensitivity (Shigella); CBC (leukocytosis; anaemia).
• Electrolytes, renal function; monitor for complications (e.g. HUS with EHEC).

MANAGEMENT

• Assess & treat dehydration (Plans A/B/C) and continue feeding — nutrition is vital as dysentery rapidly worsens nutritional status.
• Antibiotics are indicated (unlike watery diarrhoea): first-line for shigellosis is ciprofloxacin (or azithromycin / ceftriaxone as per sensitivity) for ~3–5 days.
• Amoebic dysentery: metronidazole (30–50 mg/kg/day × 7–10 days) followed by a luminal amoebicide (diloxanide furoate).
• Zinc for 14 days; vitamin A; treat associated malnutrition.
• Avoid anti-motility drugs (they worsen invasive disease).

COMPLICATIONS

• Shigella: convulsions, toxic megacolon, intestinal perforation, rectal prolapse, reactive arthritis, and haemolytic uraemic syndrome (HUS) (esp. S. dysenteriae type 1 & EHEC).
• Amoebic: liver abscess, amoeboma, perforation.
• Rapid dehydration, electrolyte imbalance and severe malnutrition.

PREVENTION

• Safe drinking water, sanitation and hand-washing (faeco-oral spread).
• Exclusive breastfeeding; hygienic food handling; prompt recognition & treatment.
• Improved nutrition and vitamin A/zinc to reduce severity.

EPIDEMIOLOGY & PATHOGENESIS

• Spread is faeco-oral via contaminated food/water and person-to-person; a very low infective dose makes Shigella highly contagious.
• Organisms invade the colonic epithelium, multiply, and produce inflammation, ulceration and micro-abscesses → blood, mucus and pus in the stool.
• S. dysenteriae type 1 produces Shiga toxin, which can damage vascular endothelium and precipitate haemolytic uraemic syndrome.

HAEMOLYTIC URAEMIC SYNDROME (HUS) — key complication

• A triad of microangiopathic haemolytic anaemia, thrombocytopenia and acute kidney injury.
• Follows Shiga-toxin-producing infection (S. dysenteriae type 1 / EHEC O157:H7); presents with pallor, oliguria and bleeding.
• Avoid antibiotics and anti-motility drugs in suspected EHEC, as they may increase the risk of HUS; management is largely supportive (± dialysis).

PROGNOSIS

With prompt rehydration, appropriate antibiotics and nutritional support, most children recover well; delay, malnutrition, very young age and complications (HUS, perforation, toxic megacolon) worsen the outcome.

ASSESSMENT AT PRESENTATION

• Confirm blood in the stool (visible or on microscopy) and assess the degree of dehydration (Plans A/B/C).
• Assess nutritional status — dysentery causes rapid protein loss and precipitates malnutrition.
• Look for danger signs — convulsions, abdominal distension (toxic megacolon), rectal prolapse, or signs of HUS (pallor, oliguria).

DIETARY & SUPPORTIVE CARE

• Continue breastfeeding and give frequent, energy-dense feeds throughout the illness.
• Give an extra meal daily for 2 weeks after recovery to make up the nutritional loss.
• Ensure zinc (14 days) and vitamin A; treat anaemia and any associated infection.

ANTIBIOTIC SELECTION

• Dysentery = blood in stool (invasive colitis); Shigella is commonest.
• Bacillary (toxic, pus cells) vs amoebic (insidious, trophozoites with RBCs).
• Antibiotics ARE indicated (ciprofloxacin/azithromycin for Shigella).
• Give zinc + nutrition; avoid anti-motility drugs.
• Watch for HUS (esp. S. dysenteriae type 1 / EHEC).

• Blood in the stool = dysentery; Shigella is the commonest, most important cause.
• Bacillary vs amoebic differ on stool microscopy and treatment.
• Antibiotics ARE indicated (unlike watery diarrhoea) — ciprofloxacin/azithromycin.
• Nutrition is vital — dysentery rapidly worsens nutritional status.
• Watch for HUS with S. dysenteriae type 1 / EHEC; avoid anti-motility drugs.