Anesthesia for pediatric patients

1. Infantile hypertrophy pyloric stenosis
Girmay T.Fitiwi
April, 2018
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2. THE STOMACH
1. Functional components
 Three functional parts of the
stomach
 Cardia
 Fundus and body
 Antrum
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3. Pyloric stenosis
• Occurs due to the hypertrophy of the gastric outlet
musculature.
• The most common surgical disorder producing emesis in
infancy/in the first three months of life.
• An acute medical emergency not a surgical emergency.
• Preoperative correction of the severe fluid and electrolyte
deficits may require several days.
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4.  Incidence
 It occurs in approximately 2-4/1000 live births with
an increased incidence in first born males.
 Males to females(4:1).
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5.  Etiology: The definitive Etiology remains unknown.
 Various theories proposed are:
 Polygenic mode inheritance
Hypoganglionosis
H.pylori infection
 Hypergastrinaemia with pylorospasm
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6.  Pathophysiology :
 Hypertrophy of the two muscle layers of the pylorus.
 The pyloric canal lengthens, the whole pylorus thickens, and
 The mucosa becomes oedematous causing functional
obstruction of the gastric outlet.
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7.  Obstruction usually develops by 2-4 weeks of age.
 Emesis is usually projectile because of the high pressure generated
by hypertrophied gastric muscles.
 Wide range of metabolic disturbance
Hypochloremic, Hypokalemic, Hypovolemic and Hyponatraemic
Metabolic alkalosis.
Hypocalcaemia may be associated
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8. Why Hypochloremic metabolic alkalosis
• Normally each mEq of gastric acid secreted causes a mEq of
HCO3- to be generated.
– HCl- lost via vomitus .
– HCO3- continues to rise in the plasma.
– kidney ride out HCO3- ( The load is high in the proximal
convoluted tubule …..NaHco3- lost with urine).
– Urine PH >7.0 /Alkaline urine.
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9.  Hypovolemia
 Due to ECF depletion …..kidney attempts to conserve Na+ by
stimulating aldostrone.
 ECF depletion followed by Na+ ….Hyponatraemia .
 Hypokalemia
 K+ is lost in the vomitus.
 H+-K+ exchange ( excretion of K+ )in the urine
Hypokalemia .
 Intracellular shift
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10. Pathophysiology
 Vomiting → loss of H⁺ and Cl⁻ → Hypochloremic hypokalemic
metabolic alkalosis.
 Protracted vomiting → ECF volume deficit → urinary excretion of K⁺
and H⁺ to preserve Na⁺ and water.
 Initial alkalotic urine becomes acidotic- Paradoxical aciduria.
 Hypochloremic hypokalemic metabolic alkalosis with paradoxical
aciduria with secondary respiratory acidosis.
 Hyponatremia may not be evident because of hypovolemia

11. Clinical Presentation
 3-5 week old infant with non-bilious projectile vomiting immediately
after feeding .
 An olive-like mass can be felt at the lateral edge of the rectus
abdominis muscle in the right upper quadrant of the abdomen.
 Signs of dehydration
 Signs of malnutrition and poor weight gain may also be apparent.
 Pre-renal failure can occur.
 Jaundice occurs = glucuronyl transferase deficiency 20 to
starvation (17%).
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12.  Ultrasound
• The size of the pylorus is measured and compared to standard values.
• Pyloric muscle thickness > 4mm.
• pyloric muscle length > 14 – 20mm.
• pyloric diameter >10-14mm is diagnostic in term infants, with both a
high sensitivity (90-99%) and high specificity (97-100%).
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13. o Upper GI Imaging
o Barium studies show classical signs of an elongated pyloric
canal (‘string sign’) or thickened pyloric mucosa (‘double-
track sign’).
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14. Barium swallow
Duodenal bulb
Air filled fundus
Barium filled antrum
Narrowed pyloric channel
String sign
Normal stomach

15. MANAGEMENT
 Resuscitation
 Initial management should follow an ‘ABC’ approach, and fluid
management should focus on correction of underlying dehydration, as
well as electrolyte and acid-base abnormalities.
 An initial bolus of 20ml / kg 0.9% saline should be used if the infant
is dehydrated.
 Maintenance fluid : maintain adequate hydration whilst protecting
against hypernatraemia and hypoglycaemia.
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16.  Maintenance fluid
 5% glucose / 0.9% saline or 0.45% saline should be used in this
situation.
 Serial electrolyte, acid-base and blood glucose measurements must
be performed.
 KCL should be added to the fluid as required once urine output has
been established.
 10-40 meq /L KCL added once urine output established.
 An accurate fluid balance chart should be kept and urinary
catheterization .
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17. Aims
• Check for signs of good hydration (alertness, skin turgor,
fontanelles, vital signs).
• Aim for /Targets for resuscitation
– pH = 7.3-7.5
– Na > 132 mmol/L
– Cl > 106mmol/L
– K >3.2 mmol/L and HCO3 < 28- 30 mmol/L.
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18. Anaesthesia
 The nasogastric tube should be aspirated before induction of
anaesthesia to minimise the risk of pulmonary aspiration of gastric
contents.
 A “4 quadrant aspiration” (turning the infant through a full rotation
and aspirating the stomach at each quarter turn) has been suggested as
being effective.
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19. Management
• Anaesthesia may be induced by inhalation with sevoflurane (or
halothane), or rapid sequence induction with either thiopentone or
propofol.
• 1-2mg/kg of Suxamethonium.
• A modified RSI with gentle positive pressure ventilation is commonly
used.
• Anaesthesia should be maintained with volatile agents
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20. Intra op fluid management
• Boluses of an isotonic fluid (saline 0.9% or hartmann’s solution)
10ml/kg may be given intraoperatively to correct circulating volume if
required.
• Glucose containing maintenance solutions may be continued in
theatre, but must NOT be used for bolus fluid replacement.
• If glucose containing maintenance fluids are discontinued intra-
operatively, the blood glucose should be checked regularly to ensure
normoglycaemia throughout the perioperative period.
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21. Post op
• Postoperative pain is not usually severe.
• intra-operatively with an IV opioid such as fentanyl 1
mcg/kg and paracetamol ( 30-40mg/kg PR).
• The wound should be infiltrated with bupivacaine 0.25% 2
mg/kg (0.8 ml/kg) where possible.
• Caudal Analgesia????Dose ???? Haemodynamic status.
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22. Postoperative Care
• Respiratory depression
• post op period and up to 7 hours after anaesthesia in full term infants.
• This may be related to a delayed correction of CNS alkalosis
affecting the pH of the CSF.
• Oral feeds are usually initiated 6-8 hours after surgery. The typical
time in hospital to return to full feeds is usually 2-3 days.
• Thus maintain iv infusion of fluids until oral intake is adequate.
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23. SUMMARY
• A common condition, occurring in 2 – 4 / 1000 live births
• Presentation is usually early, between 3 – 5 weeks of age.
• Initial management is aimed at resuscitation, correcting of
dehydration, alkalosis and electrolyte disturbances before corrective
surgery can occur .
• A variety of anaesthetic techniques have been used successfully,
although rapid sequence intravenous induction, endotracheal
intubation and maintenance with an inhalational agent is common and
safe.
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24. Anaesthetic management
• Technique: GA with controlled ventilation with
endotracheal intubation
• Goals: normoxia, Normocapnia, Normothermia
• Normovolemia and Electrolyte balance
• Avoid bradycardia, aspiration of gastric contents