Pyloromyotomy

Airway: ETT
Access: IV required
Pain: Simple analgesia and local; no opioids
Position: Supine
Time: 30 minutes to 1 hour
Blood loss: Minimal
Special: Apnoea monitoring, aspiration precautions

Pyloromyotomy is:

Patients classically are:

Considerations

Surgery is not an emergency and electrolyte and fluid state should be corrected prior to operating

  • A
    • Aspiration risk
      High risk - OGT or NGT should be placed and stomach suctioned prior to induction.
      • Four-quadrant suctioning can be performed
  • C
    • Volume state
      Must be corrected pre-operatively.
      • Frequency and amount of vomiting
      • Diarrhoea
      • Urine output
      • Perform resuscitation:
        Adequate resuscitation may take up to 72 hours.
        • Initial resuscitation of shock with standard solutions
          10-20ml/kg boluses of 0.9% NaCl to restore circulating volume.
        • Continue maintenance with salt and dextrose containing solutions
          • 4ml/kg/hr of 0.9% NaCl with 5% dextrose
          • Add potassium (40mmol/L) when UO ⩾1-2ml/kg/hr
  • F
    • Hypochloraemic metabolic alkalosis
      • Off-loading of oxygen is impaired in alkalotic states
        More important in neonates due to foetal haemoglobin level.
      • Compensatory respiratory acidosis is common
        Extent of compensation (i.e. PaCO2) is a marker of severity of dehydration.
      • Respiratory alkalosis (secondary to hypovolaemic shock) suggests critical dehydration
      • Potassium may be high, normal, or low, depending on the degree of acidosis and the volume state
        • As volume state falls, aldosterone will ↑ Na+ retention and lead to hypokalaemia
        • As hypokalaemia worsens, the kidney will then retain Na+ and eliminate H+
          This leads to a paradoxically acidic urine.
      • HCl may be used to correct severe alkalosis but is rarely necessary
      • Will be corrected by volume and Cl- resuscitation
        Aciduria will resolve when volume is restored, as the distal tubule no longer exchanges potassium and hydrogen for sodium.
    • Hyponatraemia/electrolyte derangement
      May be present but masked by dehydration. Preoperative targets:
      • pH ⩽7.45
      • BE ⩽3.5
      • HCO3- ⩽26mmol/L
      • Na+ ⩾132mmol/L
      • K+ ⩾3.5mmol/L
      • Cl- ⩾100mmol/L
      • BSL ⩾4mmol/L
  • G
    • Frequency and extent of vomiting

Preparation

  • Ensure adequately resuscitated, given by:
    • Restored circulating volume
    • Cl- is normal
    • pH is normal or approaching normal
  • Secure IV access
  • Monitoring required
    • SpO2
    • ECG
    • Blood pressure
  • Place a new large bore orogastric tube and perform 4-quadrant suction
    Premedicate with atropine (0.02mg/kg) prior to decompression.

Induction

  • Rapid sequence induction
  • Avoid opioids to reduce risk of post-operative respiratory depression

Intraoperative

  • Use of a circle circuit with pressure-supported or controlled ventilation
    • Provides better control of ventilation
    • Additional:
      • Dead space is minimal
      • Resistance mitigated by use of pressure-support or controlled ventilation
  • Paracetamol and local anaesthetic usually adequate for analgesia
    Avoid opioids; they will not breathe and don’t need it anyway.

Surgical Stages

Approach may be:

  • Open
    • RUQ
    • Periumbilical
  • 3× laparoscopic ports

Postoperative

  • Risk of respiratory depression
    Monitor for apnoeas for 24/24.

    • GA
    • Metabolic alkalosis
    • Neonate or infant
    • Hypothermia

  • Post-extubation stridor

  • Mucosal leak

    • Most serious surgical complication
    • May be tested for intraoperatively by instilling gas or saline down the orogastric

References