What are the guidelines for Total Intravenous Anesthesia (TCI) anesthesia?

Guidelines for Total Intravenous Anesthesia (TIVA) with Target-Controlled Infusion (TCI)

For general anesthesia, use propofol TCI at an effect-site target of 0.5-1 mcg/ml combined with remifentanil TCI at 1-3 ng/ml, avoiding bolus dosing to prevent over-sedation and respiratory depression, particularly when used together. 1

Drug Selection and Dosing

Propofol TCI Dosing

• Induction: Target effect-site concentration of 1.5-2 mcg/ml for rapid onset 2
• Maintenance: Target effect-site concentration of 0.5-1 mcg/ml 1
• Critical warning: Doses exceeding 1.5 mcg/ml carry significant risk of over-sedation and hypoventilation, especially with concomitant opioid use 1
• Avoid bolus dosing of propofol during TIVA to prevent hemodynamic instability 1

Remifentanil TCI Dosing

• Induction: 0.5-1 mcg/kg/min infusion rate, or 1 mcg/kg bolus over 30-60 seconds if intubation occurs within 8 minutes 3
• Maintenance: Effect-site target of 1-3 ng/ml 1
• Alternative maintenance dosing: 0.4 mcg/kg/min with nitrous oxide, 0.25 mcg/kg/min with isoflurane or propofol 3
• Avoid bolus dosing during maintenance to prevent respiratory depression 1, 3
• Titration: Adjust in 25-100% increments upward or 25-50% decrements every 2-5 minutes 3

Alternative Opioid Options

• Fentanyl: 0.5-1 mcg/kg boluses as needed 1
• Alfentanil: 5 mcg/kg initial bolus, then 1-3 mcg/kg as required 1

Essential Safety Measures

Depth of Anesthesia Monitoring

• Use processed EEG monitoring (BIS or Entropy) targeting BIS 40-60 to prevent awareness and avoid excessive anesthetic depth 1, 4, 5
• Depth monitoring is particularly critical in high-risk situations: patients with low blood pressure, low propofol concentrations, low body weight (≤18 kg), obesity, difficult IV access monitoring, or when using neuromuscular blocking agents 4
• Automated TCI systems using BIS feedback maintain adequate anesthesia (BIS 40-60) 94% of the time versus 74% with manual adjustment 5

Neuromuscular Monitoring

• Quantitative neuromuscular monitoring is mandatory when using muscle relaxants 1
• Document train-of-four ratio ≥0.90 before extubation to ensure complete reversal 1

Hemodynamic Monitoring

• Establish invasive arterial blood pressure monitoring before induction when feasible, with transducer at tragus level 1
• If time does not permit arterial line placement, use non-invasive blood pressure at 1-minute intervals during induction 1
• Have vasopressors immediately available (ephedrine or metaraminol) to treat hypotension 1

Special Population Modifications

Elderly Patients (>65 years)

• Reduce starting doses by 50% and titrate cautiously to effect 3

Obese Patients (>30% over ideal body weight)

• Calculate all remifentanil doses based on ideal body weight (IBW), not actual weight 3
• Consider propofol dosing based on lean body weight 1
• Assume all obese patients have some degree of sleep-disordered breathing and modify technique accordingly 1

Pediatric Patients (1-12 years)

• Remifentanil maintenance: 0.25 mcg/kg/min (range 0.05-1.3 mcg/kg/min) with volatile agents 3
• Neonates (birth to 2 months): 0.4 mcg/kg/min (range 0.4-1.0 mcg/kg/min) with nitrous oxide 70% 3
• Neonatal clearance is highly variable, averaging twice that of adults, potentially requiring higher infusion rates 3
• Use atropine pretreatment to blunt bradycardia risk 3

Cardiac Surgery

• Induction: Remifentanil 1 mcg/kg/min 3
• Maintenance: 0.125-4 mcg/kg/min with supplemental boluses of 0.5-1 mcg/kg 3
• ICU continuation: 0.05-1 mcg/kg/min 3

Practical Setup and Safety Protocols

Equipment Preparation

• Ensure familiarity with TCI pump programming and operation before use 4
• Use a modified connection method with dedicated IV line for TIVA drugs to prevent inadvertent bolus administration 4
• Clear IV tubing upon discontinuation to prevent inadvertent later administration 3

Simplified Dosing Formulas

The Society for Intravenous Anesthesia recommends these memory aids for general population 4:

• "4321" for propofol with fentanyl/alfentanil 4
• "42222111" for propofol with remifentanil 4
• "4321" for pediatric patients with propofol and fentanyl 4

Emergence and Recovery

Transition to Postoperative Analgesia

• Administer longer-acting analgesics 30 minutes before end of surgery (e.g., morphine 0.1 mg/kg) 2
• Remifentanil provides no residual analgesia within 5-10 minutes of discontinuation 3
• For postoperative continuation: Start at 0.1 mcg/kg/min, adjust by 0.025 mcg/kg/min increments every 5 minutes 3
• Rates >0.2 mcg/kg/min cause respiratory depression (respiratory rate <8 breaths/min) 3

Extubation Protocol

• Ensure return of airway reflexes and adequate tidal volumes before extubation 1
• Extubate awake in sitting position 1
• For obese patients with confirmed OSA, insert nasopharyngeal airway before emergence 1
• Reinstate home CPAP immediately upon return to ward if patient uses it 1

Advantages of TIVA-TCI

• Hemodynamic stability throughout perioperative period when properly titrated 2, 6
• Reduced postoperative nausea and vomiting compared to volatile anesthetics 1, 6
• Rapid, predictable emergence with fast return of airway reflexes 1, 2
• Automated systems reduce anesthesiologist workload by 94% time in target BIS range versus 74% with manual adjustment 5
• Allows scheduled extubation timing in cardiac surgery patients (mean 163±45 minutes post-ICU arrival) 2

Critical Pitfalls to Avoid

• Never use remifentanil or propofol as sole induction agents due to inability to ensure loss of consciousness and high incidence of apnea, muscle rigidity, and tachycardia 3
• Never administer bolus doses during maintenance of either propofol or remifentanil in spontaneously breathing patients 1, 3
• Never combine propofol >1.5 mcg/ml with opioids without expecting significant respiratory depression 1
• Never discontinue remifentanil without prior administration of longer-acting analgesics for procedures with anticipated postoperative pain 3, 2
• Never dose remifentanil on actual body weight in obese patients—always use ideal body weight 3