Remifentanil TCI Infusion Protocol for Anaesthesia
For general anaesthesia maintenance, initiate remifentanil TCI at an effect-site target concentration of 3-5 ng/ml, with typical maintenance targets of 2-4 ng/ml depending on surgical stimulus and concurrent hypnotic depth. This dosing achieves drug administration consistent with FDA-approved recommendations of 0.25 μg/kg/min maintenance infusion rates 1.
Induction and Maintenance Dosing
Standard Adult Protocol
Induction:
- Target effect-site concentration: 4 ng/ml achieves dosing equivalent to the FDA-recommended bolus of 0.5-1 μg/kg 1
- This applies across the Minto, Eleveld, and Kim pharmacokinetic models with minor variations
Maintenance:
- Standard target: 3-4 ng/ml (equivalent to 0.25 μg/kg/min infusion) 2, 1
- Adjust in 0.5-1 ng/ml increments based on surgical stimulus and hypnotic depth
- Maximum recommended: 5 ng/ml before risk of significant respiratory depression increases
Pediatric Dosing (Birth to 12 Years)
Continuous infusion: 0.05-0.3 μg/kg/min 3
- Neonates and infants require lower end of range
- Must be combined with appropriate hypnotic agent
- Pretreatment with atropine recommended to prevent bradycardia 2
Specific Clinical Scenarios
At-Risk Extubation Protocol
When using remifentanil for smooth emergence in difficult airway cases 4:
- Before end of procedure: Set remifentanil at desired maintenance rate
- Discontinue hypnotic (propofol or volatile agent) while continuing remifentanil
- Continue ventilation until patient opens eyes to command
- Titrate down if spontaneous respiration inadequate (reduce by 25-50%)
- Discontinue immediately upon extubation and flush IV line thoroughly
- Critical warning: Post-extubation respiratory depression risk persists—close monitoring mandatory until fully recovered
Monitored Anaesthesia Care (MAC)
Single dose approach:
- 0.5-1 μg/kg over 30-60 seconds, given 90 seconds before local anaesthetic placement 2
Continuous infusion approach:
- Initial target: 1-2 ng/ml for conscious sedation 5, 6
- Optimal target: 3 ng/ml provides effective sedation without significant respiratory depression during spinal anaesthesia 5
- Higher targets (3.5 ng/ml) significantly increase respiratory depression and PONV without additional benefit 5
- For cataract surgery with propofol TCI (1 μg/ml): remifentanil target of 1 ng/ml provides optimal patient and surgeon satisfaction 6
Awake Fiberoptic Intubation
Effect-site target: 0.8 ng/ml provides superior conditions compared to manual infusion 7
- More stable vital signs
- Less recall and pain
- Shorter preparation time
- Better sedation quality
Postoperative Analgesia Continuation
Only under direct anesthesia practitioner supervision 2:
- Initial rate: 0.1 μg/kg/min (approximately 1.5-2 ng/ml target)
- Adjust by 0.025 μg/kg/min increments every 5 minutes
- Maximum: 0.2 μg/kg/min (respiratory rate <8/min beyond this)
- Critical: Transition to longer-acting analgesics before discontinuation—remifentanil provides NO residual analgesia within 5-10 minutes of stopping 2
Age-Specific Modifications
Geriatric Patients (>65 Years)
Reduce all starting doses by 50% 2:
- Induction target: 2 ng/ml (not 4 ng/ml)
- Maintenance target: 2 ng/ml (not 4 ng/ml)
- Titrate cautiously upward based on response
- Effect-site targeting requires even lower targets due to increased sensitivity
Obese Patients
Use lean body weight for dosing calculations 8
- Plasma targets of 3-5 ng/ml remain appropriate 1
- Standard TCI models (Minto, Eleveld) account for obesity when programmed correctly
Critical Safety Considerations
Respiratory Depression Management
Muscle rigidity and chest wall rigidity occur with:
- Single doses >1 μg/kg over 30-60 seconds
- Infusion rates >0.1 μg/kg/min
- Any bolus when combined with continuous infusion 2
Management:
- Immediate neuromuscular blockade for life-threatening rigidity
- Reduce or stop infusion for spontaneously breathing patients
- Naloxone as rescue (but eliminates all analgesia)
- Resolution occurs within minutes of stopping infusion
Mandatory Monitoring
- Continuous capnography until airway device removed and verbal response established 9
- Pulse oximetry, ECG, blood pressure throughout
- Respiratory rate monitoring critical—depression occurs before desaturation 10, 11
IV Line Management
Flush IV tubing thoroughly after discontinuation 2:
- Residual remifentanil causes delayed respiratory depression, apnea, and muscle rigidity when other fluids administered through same line
- This is a frequently reported complication
- Use dedicated IV line when possible
Drug Interactions
Avoid bolus dosing when combining with:
- Benzodiazepines (start at lowest effective dose) 2
- Other CNS depressants
- Serotonergic drugs (risk of serotonin syndrome) 2
Never administer into same IV line as blood products—nonspecific esterases inactivate remifentanil 2
Practical TCI Model Selection
All three validated models (Minto, Eleveld, Kim) produce similar clinical results when targeting plasma concentrations of 3-5 ng/ml for initial dosing 1. The Minto model remains most widely validated across age ranges and clinical scenarios.
Effect-site targeting provides smoother titration but requires understanding of ke0 (effect-site equilibration) for each model—typically 1-2 minutes for remifentanil.