Endoscopy

Time: Gastroscopy ~10-15 minutes, Colonoscopy up to ~45 minutes Pain: Position: Colonscopy: lateral (occasionally changing to supine); gastrocopy: sitting head-up; ERCP: swimmer’s position Blood loss: None (except emergent gastroscopy for haematemesis) Special Drugs

Endoscopy:

Considerations

  • Indication for procedure
    Conditions with risk of:
    • Airway difficulty
    • Reduced safe apnoea time
    • Aspiration Pathologies with high-risk of aspiration include:
      • Gastric outlet obstruction
      • Achalasia
      • Upper GI bleeding
      • Oesophageal stricture
        Especially if being dilated.
      • Bowel obstruction
      • Pharyngeal pouch
  • A
    • Aspiration is always a risk with an unprotected airway
    • Predicted difficulty with airway management
      • Position
        Positioning prone or in swimmers position (for ERCP) may necessitate intubation.
      • Known or expected difficult airway
      • Sleep apnoea
  • B
    • Hypoxia is the main complication of endoscopy sedation
    • Preoxygenation is vital to prolong safe apnoea time
      Especially in shared airway (gastroscopy, ERCP).
  • C
    • CVS instability may occur at deeper levels of sedation
  • D
    • Ease of performing procedural sedation
      Factors predicting poor response include:
      • Prior difficulty
      • Current benzodiazepine or opioid use
      • Heavy alcohol use
    • Depth of sedation
      Corresponds with risk of perforation.
  • E
    • Remote location of endoscopy suite relative to other parts of the hospital

Preparation

  • Standard ANZCA monitoring
  • Readily accessible IV access
  • End-tidal CO2 monitoring
    Provides early warning of loss of airway patency prior to desaturation.
  • Supplemental oxygen
    • Bite block with integrated O2
    • Hudson mask
    • High-flow oxgygen
  • Airway adjuncts
    • NPA are useful
      Oxygen can also be run through a suction catheter to provide oxygen to the nasopharynx.

Induction - Sedation Free

  • Topical local anaesthetic
    Lignocaine/benzocaine spray to oropharynx.
    • Reduces patient discomfort
    • Improves ease of procedure

Induction - Sedation

Many strategies exist:

  • Topical local anaesthetic
    Reduces anaesthesia requirement.

  • Propofol alone

    • Typically 1-1.5mg/kg IV followed by 10-20mg boluses as required
      Actual patient requirements may be highly variable.
      • ~1.3mg/kg for gastroscopy and ASA 1 colonoscopy
      • ~0.7mg/kg for ASA 4 colonoscopy
    • May also be run via propofol TCI
      Typically target Ce of 3ug/ml.
    • May also be run as a rate-controlled infusion
      Bolus and the infuse at ~1mg/kg/hr.
      • Works best once steady-state is already established

  • Propofol and fentanyl

    • Typically ~0.5-1ug/kg of fentanyl and propofol ~0.5-1mg/kg, followed by propofol boluses as required

Intraoperative

Main intraoperative challenges include:

  • Regurgitation and aspiration
    • May be foreshadowed by the patient swallowing
  • Desaturation
    • Maintaining a patent airway provides passage for apnoeic oxygenation
    • Generally treated by reducing sedation and providing supplmental oxygen
      • ↑ nasal prong O2 flows
      • Provide high-flow nasal oxygen
    • May require intubation
  • CVS instability
    • May be either bradycardia or hypotension
    • Bradycardia may also be due to bowel insufflation

Surgical Stages

Colonoscopy:

  • Insertion well tolerated
  • Level of stimulation is usually constant throughout procedure

Gastroscopy:

  • Insertion is stimulating
    Should correspond with peak concentration of propofol
  • Remainder of procedure is generally unstimulating

Postoperative

References

  1. Heuss LT, Schnieper P, Drewe J, Pflimlin E, Beglinger C. Risk stratification and safe administration of propofol by registered nurses supervised by the gastroenterologist: a prospective observational study of more than 2000 cases. Gastrointest Endosc. 2003 May;57(6):664-71.
  2. Cohen LB, Delegge MH, Aisenberg J, Brill JV, Inadomi JM, Kochman ML, Piorkowski JD Jr. AGA Institute. AGA Institute review of endoscopic sedation. Gastroenterology. 2007 Aug;133(2):675-701.