What is the recommended anesthesia regimen for endoscopic spine surgery using propofol (Propofol), ketamine (Ketamine), and remifentanil (Remifentanil)?

Recommended Anesthesia Regimen for Endoscopic Spine Surgery

For endoscopic spine surgery with only propofol, ketamine, and remifentanil available, use a balanced TIVA approach: propofol target-controlled infusion (effect-site concentration 0.5-1 mcg/mL) combined with remifentanil infusion (0.05-0.3 mcg/kg/min) plus ketamine (0.5 mg/kg bolus followed by 0.1-0.2 mg/kg/h infusion), with BIS monitoring targeting 40-60. 1

Induction Protocol

• Administer ketamine 0.5 mg/kg IV bolus first to provide baseline analgesia and hemodynamic stability 1
• Follow with propofol via target-controlled infusion targeting effect-site concentration of 0.5-1 mcg/mL, avoiding bolus dosing to prevent hemodynamic instability 1
• Start remifentanil infusion at 0.5-1 mcg/kg/min for induction, then reduce to maintenance dose after intubation 2
• Administer rocuronium 0.9-1.2 mg/kg for neuromuscular blockade if available 1

Maintenance Regimen

The three-drug combination provides synergistic benefits: propofol for hypnosis, remifentanil for potent analgesia, and ketamine to counteract remifentanil-induced bradycardia/hypotension while reducing postoperative opioid requirements 3, 4, 5

Specific Dosing During Maintenance:

• Propofol: Continue TCI at 0.5-1 mcg/mL effect-site concentration 1
• Remifentanil: 0.05-0.3 mcg/kg/min continuous infusion (typically 0.2 mcg/kg/min for spine surgery) 2, 4, 5
• Ketamine: 0.1-0.2 mg/kg/h continuous infusion (equivalent to 1-3 mcg/kg/min) 1, 4, 5

Titration Strategy:

• Adjust remifentanil in 25-50% increments every 2-5 minutes based on surgical stimulation 2
• For transient intense surgical stress, administer remifentanil 1 mcg/kg bolus every 2-5 minutes as needed 2
• Avoid ketamine boluses during maintenance to prevent emergence phenomena; use continuous infusion only 1

Critical Monitoring Requirements

Mandatory monitoring includes: 1

• BIS monitoring targeting 40-60 throughout the procedure (avoid BIS <35 in patients >60 years to reduce delirium risk)
• Invasive arterial blood pressure monitoring established before induction when feasible
• Quantitative neuromuscular monitoring if muscle relaxants used, documenting train-of-four ratio ≥0.90 before extubation
• Continuous pulse oximetry and capnography to detect early respiratory depression

Safety Considerations and Common Pitfalls

Respiratory Depression Risk:

The propofol-remifentanil combination produces synergistic respiratory depression beyond either agent alone 6, 7. Adding ketamine does NOT eliminate this risk but improves hemodynamic stability 3, 8.

• Have airway management equipment immediately available including bag-mask ventilation capability 6
• Maintain vascular access throughout the procedure 7
• Supplemental oxygen is mandatory 7

Hemodynamic Management:

Ketamine addition significantly reduces intraoperative bradycardia and hypotension compared to propofol-remifentanil alone 3, 4, 5. Studies in spine surgery show:

• Fewer episodes of HR <50 bpm and SBP <80 mmHg with ketamine 3
• Better hemodynamic stability during prolonged procedures 4, 5

Keep vasopressors immediately available (ephedrine or metaraminol) despite ketamine's sympathomimetic effects 1

Dosing Pitfalls to Avoid:

• Do NOT use propofol or remifentanil as sole agents - propofol lacks analgesic properties and remifentanil cannot guarantee loss of consciousness 2
• Reduce propofol doses by 50-75% when combining with remifentanil compared to monotherapy 7, 2
• Never administer remifentanil boluses for postoperative pain - its ultra-short duration makes this ineffective 2

Adjunctive Medications

Administer dexamethasone 0.15-0.25 mg/kg (maximum 0.5 mg/kg) at induction to reduce postoperative swelling and inflammation 1

Emergence and Postoperative Transition

Discontinuation Strategy:

• Stop remifentanil infusion at surgical closure - recovery occurs within 5-10 minutes regardless of infusion duration 2
• Stop ketamine infusion 10-15 minutes before anticipated end to allow clearance 1
• Continue propofol until adequate spontaneous ventilation returns 1

Postoperative Analgesia:

The ketamine infusion significantly reduces postoperative opioid requirements 3, 4, 5. Studies show:

• 38% reduction in 24-hour morphine consumption with intraoperative ketamine 4, 5
• Longer time to first analgesic request in ketamine groups 3, 4

For PACU breakthrough pain, titrate fentanyl 0.5-1.0 mcg/kg IV to effect 6, 1

Transition to multimodal oral analgesia as soon as possible: 6, 1

• Scheduled NSAIDs (if not contraindicated)
• Scheduled acetaminophen 10-15 mg/kg every 6 hours
• Reserve opioids for severe breakthrough pain only

Critical Warning About Delayed Respiratory Depression:

No cases of remifentanil-induced delayed respiratory depression occur >30 minutes after discontinuation 2. However, if transitioning to longer-acting opioids (morphine, fentanyl) before full emergence, monitor closely for respiratory depression 2.