Challenges of TIVA in Emergency Surgery

Emergency Surgery

• Rapid Sequence Induction (RSI), or a modified version of it, is frequently used to intubate the trachea in emergency situations
• Generally, it includes
  • Denitrogenation by pulmonary pre-oxygenation
  • Administering a pre-determined dose of rapidly acting anaesthesia induction agent followed immediately by the administration of a fast-acting muscle relaxant
    • Thiopentone was traditionally the induction of agent of choice due to its reliable and rapid clinical effect
    • Propofol in recent years has gained popularity due to familiarity
    • The time to peak effect of propofol is longer than thiopentone (approximately twice as long)
  • Application of cricoid pressure (Sellick’s manoeuvre)
    • The usefulness of cricoid pressure is controversial and the evidence base is weak
• Nature of pathology that requires emergency surgery
  • Trauma
  • Postoperative complications or unwell surgical patients
  • Critically ill medical patients with hypoxaemia
• Challenges of emergency surgery
  • Pulmonary aspiration as a result of inadequate or unreliable fasting (full stomach)
    • Traditional teaching dictates that all emergency, trauma and obstetric patients are presumed to have a full stomach
    • Increasing use of preoperative gastric ultrasound can select those at high risk from this population
    • Rapid administration of propofol and muscle relaxant goes against the concept of slow titration to the clinical effect that has prevailed in the teachings of the previous weeks
  • Deranged physiology
  • Increased bleeding risk
    • Blood loss during surgery in particular emergency operations is common
    • Propofol has a very large volume of distribution
    • Therefore even large blood loss will have little effect on plasma concentrations
      • TCI and manual infusion do not need adjustment
    • Increased pharmacodynamic sensitivity of anaesthetic drugs is with hypovolemia
    • Reduction in organ blood flow (particularly hepatic) will reduce propofol clearance and may increase blood concentrations.
      • The same phenomenon was observed in hepatobiliary surgery with the Pringle manoeuvre (hepatic vascular clamps)
• pEEG monitoring during major emergency/ elective surgery with any anaesthetic technique allows us to titrate
• Ketamine is useful as a propofol sparing adjunct

Caution is required in patients with haemodynamic compromise. TCI in emergencies is not for novices and we need to develop these skills in normal, healthy patients first.