What is Total Intravenous Anesthesia (TIVA)?

Total Intravenous Anesthesia (TIVA)

Total Intravenous Anesthesia (TIVA) is an anesthetic technique that uses continuous intravenous infusion of anesthetic agents for induction and maintenance of general anesthesia without the use of inhaled anesthetic gases. This technique relies on carefully titrated IV medications to achieve hypnosis, analgesia, and when needed, muscle relaxation 1.

Key Components of TIVA

Medications Used

• Hypnotic agents: Propofol is the most commonly used agent for induction and maintenance due to its rapid onset, short duration of action, and favorable recovery profile 1, 2
• Analgesic agents: Short-acting opioids such as remifentanil are typically used due to their rapid onset and offset 3, 1
• Muscle relaxants: When required, agents like rocuronium or succinylcholine may be used with appropriate monitoring 1, 2

Delivery Systems

1. Manual infusion: Using standard infusion pumps with calculated dosing
2. Target-Controlled Infusion (TCI): Computer-assisted systems that calculate infusion rates based on pharmacokinetic models to achieve target plasma or effect-site concentrations 2, 4

Monitoring Requirements

• Standard monitoring: ECG, SpO₂, NIBP (required for all anesthesia) 1
• Processed EEG monitoring: Strongly recommended during TIVA with neuromuscular blockade to assess depth of anesthesia and prevent awareness 1, 2
• Quantitative neuromuscular monitoring: Essential whenever neuromuscular blocking drugs are administered 1

Safety Considerations for TIVA

Critical Safety Measures

1. Continuous infusion maintenance: Any interruption in drug delivery may result in awareness; thorough equipment checks are essential 1
2. Intravenous access protection:
   • Anti-reflux/non-return valves must be used on IV infusion lines 1
   • IV sites must remain visible to monitor for disconnection or infiltration 1
3. Staff training: Clinical staff must be properly trained in the use and checking of TIVA equipment 1, 4
4. Equipment labeling: IV connectors and valves should be clearly labeled 1

Advantages of TIVA

1. Reduced postoperative nausea and vomiting compared to inhalational techniques 1, 5
2. Rapid, clear-headed emergence from anesthesia 5
3. Avoidance of pollution in the operating room environment
4. Hemodynamic stability when properly titrated 6
5. Reduced stress response to surgery compared to some inhalational techniques 6
6. Suitable for patients with malignant hyperthermia risk or when inhalational anesthesia is contraindicated 4

Potential Challenges and Pitfalls

1. Risk of awareness: Without end-tidal gas monitoring available (as with inhalational anesthetics), processed EEG monitoring becomes crucial to prevent awareness, especially when neuromuscular blocking agents are used 1, 4
2. Equipment failure: Alternative means of anesthesia delivery must be immediately available 1
3. Pharmacokinetic variability: Individual patient response may vary, requiring careful titration and monitoring 2
4. Increased vasopressor requirements: Propofol can cause more pronounced hypotension in hemodynamically challenged patients 1

Practical Implementation

1. Preoperative preparation:

   • Check all equipment thoroughly
   • Ensure backup delivery systems are available
   • Verify IV access is secure and visible

2. Induction:

   • Typically with propofol bolus (1.5-2.5 mg/kg)
   • Short-acting opioid administration
   • Neuromuscular blockade if required

3. Maintenance:

   • Continuous propofol infusion (typically 4-12 mg/kg/h, adjusted based on patient response)
   • Continuous or intermittent opioid administration
   • Processed EEG monitoring to guide anesthetic depth

4. Emergence:

   • Discontinue infusions with appropriate timing based on context-sensitive half-times
   • Continue monitoring until full recovery of consciousness and protective reflexes

Special Populations

• Elderly patients: Require reduced dosing and may benefit from processed EEG monitoring to avoid excessive anesthetic depth 2
• Pediatric patients: TIVA is increasingly used in children, with appropriate weight-based dosing adjustments 7
• Obese patients: Standard pharmacokinetic models may become unreliable above 140-150kg; careful titration to effect is essential 2

TIVA represents an important alternative to inhalational anesthesia with distinct advantages in certain clinical scenarios. Proper understanding of the pharmacokinetics, appropriate monitoring, and attention to safety considerations are essential for its successful implementation.