Total Intravenous Anaesthesia (TIVA) and Target Controlled Infusion (TCI)

Quick Answer

Total intravenous anaesthesia (TIVA) provides complete anaesthesia without volatile agents using continuous IV drug infusions, offering advantages in PONV reduction (50% lower than volatiles), neurosurgery (reduced cerebral blood flow, easier wake-up for neurological assessment), and malignant hyperthermia-susceptible patients. Target controlled infusion (TCI) systems automate drug delivery using pharmacokinetic models to achieve and maintain desired plasma (Cp) or effect-site (Ce) concentrations. Propofol TCI uses Marsh or Schnider models (Marsh: age/weight-based, Schnider: includes height/lean body mass) with typical effect-site target 3-6 μg/mL for general anaesthesia. Remifentanil TCI uses Minto model (age/weight/height) with effect-site target 3-8 ng/mL, providing potent analgesia with context-sensitive half-time 3-5 minutes regardless of infusion duration due to esterase metabolism. Depth of anaesthesia monitoring (BIS 40-60) is essential with TIVA as lack of volatile agent eliminates end-tidal monitoring capability. Pharmacokinetic principles: Propofol high lipophilicity (Vdss 2-10 L/kg), hepatic metabolism (glucuronidation), context-sensitive half-time 20-45 minutes after 1-4 hour infusion. Propofol infusion syndrome is rare but catastrophic complication (metabolic acidosis, cardiac failure, rhabdomyolysis) associated with high doses (>4 mg/kg/hour for >48 hours) in critically ill patients. Indigenous patients may have altered drug metabolism due to higher rates of obesity and liver disease, requiring careful TCI dosing and BIS monitoring to prevent awareness or overdose. [1-10]