• Pyloric stenosis
    • One of the most common GI abnormalities in the first 6 months of life
    • Aetiology
      • Commoner in white population
      • M:F = 4:1
      • More common in autumn/spring
      • Infection, hypergastrinaemia and immaturity of ganglion cells have been proposed as causes
      • Usually presents between 3rd & 5th wks of life
      • Usually occurs in full term infants
      • Associated abnormalities seen in 6-20%
        • Hirschprung's
        • Malrotation
        • Oesophageal atresia
    • Clinical signs
      • Dehydration
      • Projectile vomiting
      • Weight loss/FTT
      • Upper abdominal distension
      • Visible peristalsis during feeds
    • Pathophysiology
      • Vomiting causes loss of Na⁺, K⁺, acid and water
      • In pyloric stenosis, H⁺ is lost out of proportion to HCO₃ˉ
      • Increased serum HCO₃ˉ is presented in the glomerular filtrate and makes the urine alkalotic
      • Kidneys try to reabsorb Na⁺ due to ECF depletion
      • This causes hypokalaemia exacerbated by the kidney trying to preserve H⁺ (also exchanged for K⁺) to maintain normal pH
      • Loss of Clˉ results in hypochloraemia
      • The kidneys try to preserve the Clˉ but there is insufficient to absorb alongside the Na⁺
      • Hypokalaemia eventually forces Na⁺ to exchange for H⁺, causing the paradoxical aciduria during alkalaemia in pyloric stenosis
      • Only once chloride is restored can the the excretion of bicarbonate occur
      • Urine Clˉ >20mmol/L suggest the ECF has been corrected
    • Correction
      • It is a medical emergency, not a surgical one
      • Biochemical resolution must occur before surgery
    • Management
      • Insert NGT and do 4hr washouts
      • Severe dehydration
        • 20ml/kg N/Saline or gelofusine bolus
      • Moderate dehydration
        • 0.45% Saline/5% dextrose + 10mmol KCl at 6-8ml/kg/hr
      • NG losses matched ml for ml with N/Saline
      • Once targets achieved use 4% glucose/0.18% Saline at 4ml/kg/hr
      • Resuscitation targets
        • Serum Clˉ >106
        • Serum Na⁺ >135
        • Serum HCO₃ˉ <26
        • Urine Clˉ >20
        • UO >1ml/kg/hr
      • Anaesthetic
        • NG aspiration in L & R lateral head down
        • Gastric lavage with N/saline
        • Gas or IV induction are used (thio 5-7mg/kg & sux 2mg/kg)
        • IV atropine 20mcg/kg is given
        • Size 3.5 ETT used
        • Muscle relaxants help surgical field
        • Surgeon may ask for inflation via NGT to test mucosal integrity
        • Opiates rarely needed
        • Temp monitoring and warming is needed
        • Apnoea monitor post-op
        • Feed 12hr post op
      • Surgical
        • Ramstedt pyloromyotomy
        • Via right subcostal incision
        • Generally safe procedure but can cause mucosal perforation
    • Investigations
      • Bloods
        • Hypochloraemic, hypokalaemic, hyponatraemic metabolic alkalosis
      • USS
      • Barium meal
    • CEACCP
      Link:ceaccp.oxfordjournals.org/content/1/3/85.full.pdf?sid=e08cca86-87ab-4dc2-84bc-bd29ed267506