Here's a concise yet comprehensive guide to TIVA implementation in modern anesthesia practice, including common regimens, dosing, and key considerations:
Core Components of TIVA
TIVA combines two IV agents:
- Hypnotic: Propofol (primary).
- Analgesic: Opioid (e.g., remifentanil, fentanyl) or adjunct (e.g., dexmedetomidine).
Standard TIVA Regimens & Dosing
1. Propofol-Based TIVA
- Induction:
- Propofol: 1.5–2.5 mg/kg IV (slow bolus).
- Maintenance:
- Manual Infusion: 100–200 mcg/kg/min (titrate to BIS 40–60).
- TCI (Target-Controlled Infusion):
- Target plasma concentration: 3–6 mcg/mL (adjust for age/comorbidities).
- Example: 35-year-old adult → Start at 4 mcg/mL, titrate ±0.5 mcg/mL.
2. Propofol + Remifentanil (Gold Standard)
- Induction:
- Propofol: 1–1.5 mg/kg + Remifentanil: 0.5–1 mcg/kg IV.
- Maintenance:
- Propofol: TCI 2–4 mcg/mL OR 50–150 mcg/kg/min.
- Remifentanil:
- Manual: 0.05–0.3 mcg/kg/min.
- TCI: Target 2–6 ng/mL.
- Key: Remifentanil allows rapid titration; stop 10–15 min before end for fast emergence.
3. Propofol + Fentanyl
- Induction:
- Propofol: 1.5–2 mg/kg + Fentanyl: 1–2 mcg/kg IV.
- Maintenance:
- Propofol: 100–150 mcg/kg/min.
- Fentanyl: 0.5–1 mcg/kg/h (supplemental boluses 0.5 mcg/kg PRN).
- Use Case: Longer surgeries (>2 hrs) where remifentanil’s cost/short action is impractical.
4. Opioid-Sparing Regimens
- Dexmedetomidine Adjunct:
- Bolus: 0.5–1 mcg/kg over 10 min (pre-induction).
- Infusion: 0.2–0.7 mcg/kg/h + reduced propofol (30–50% lower dose).
- Benefits: Less hypotension, smoother emergence, opioid-sparing.
Key Practical Considerations
1. Target-Controlled Infusion (TCI) Systems
- How it works: Uses pharmacokinetic models (e.g., Marsh, Schnider) to achieve target plasma/effect-site concentrations.
- Advantages:
- Predictable drug levels.
- Automatic adjustment for age/weight.
- Common Models:
- Marsh: For propofol (weight-based).
- Minto: For remifentanil (age/weight-adjusted).
2. Monitoring Essentials
- Depth of Anesthesia: BIS/Entropy (target 40–60).
- Hemodynamics: Beat-to-beat BP/HR (propofol causes vasodilation; remifentanil causes bradycardia).
- Ventilation: EtCO₂ and SpO₂ (apnea risk with boluses).
3. Special Populations
|
Population
|
Propofol Adjustment
|
Opioid Adjustment
|
|---|---|---|
| Elderly | ↓ 30–50% (TCI start at 2–3 mcg/mL) | ↓ Remifentanil (TCI 2–4 ng/mL) |
| Obesity | Use lean body weight (LBW) | Remifentanil by TBW |
| Cardiac | ↓ 20–30% + vasopressor ready | Avoid remifentanil boluses |
4. Emergence & Recovery
- Propofol: Stop 5–10 min before end.
- Remifentanil: Stop 10–15 min before end (context-sensitive half-life <5 min).
- Transition to Analgesia:
- Give longer-acting opioid (e.g., morphine 0.1 mg/kg) 20 min before stopping remifentanil.
Safety & Pitfalls
- Propofol Infusion Syndrome (PRIS):
- Risk: Doses >4 mg/kg/h for >48 hrs.
- Prevention: Limit infusion duration; monitor lactate/CK.
- Awareness:
- Ensure BIS monitoring + double-check infusions.
- Hypotension:
- Preload with 500 mL crystalloid; use vasopressors (e.g., phenylephrine).
When to Choose TIVA
- Malignant Hyperthermia (MH) risk: Avoids volatile agents.
- Neurosurgery: Better cerebral perfusion control.
- PONV-prone patients: Reduced nausea vs. volatiles.
- Airway surgery: Avoids airway irritation.
- Outpatient/short cases: Faster recovery (e.g., remifentanil-based TIVA).
Key Takeaway
TIVA = Precision Anesthesia: Use propofol TCI (2–6 mcg/mL) + remifentanil TCI (2–6 ng/mL) for most cases. Adjust for age/comorbidities, monitor BIS, and plan emergence analgesia. Always have vasopressors and rescue airway equipment ready!
Further Reading:
