What is the recommended opioid-based induction method?

Recommended Opioid-Based Induction Method

The recommended opioid-based induction method for anesthesia involves using short-acting potent opioids such as remifentanil or fentanyl to attenuate the stress response, combined with appropriate hypnotic agents and neuromuscular blocking agents. 1

Primary Opioid Selection

• Remifentanil is preferred for induction due to its ultra-short acting profile, allowing for rapid titration and minimal residual effects post-procedure 1, 2
• Fentanyl is an appropriate alternative when remifentanil is unavailable, with dosing of 1-2 mcg/kg for induction 1, 3
• Short-acting opioids should be administered before or during induction to attenuate the stress response to laryngoscopy and intubation 1

Dosing Strategy

• For remifentanil: Initial dose of 1 mcg/kg followed by infusion of 0.25-0.5 mcg/kg/min during induction 2
• For fentanyl: 1-2 mcg/kg bolus during induction, with reduced doses (approximately 25-50% reduction) advised for patients over 70 years 1
• Titrate to effect while monitoring for respiratory depression and hemodynamic changes 1

Combination with Other Agents

• Pair opioids with appropriate hypnotic agents (propofol, ketamine) to ensure adequate depth of anesthesia 1
• Use neuromuscular blocking agents (preferably rocuronium) to improve intubating conditions and reduce complications 1
• Consider ketamine as the hypnotic agent of choice in hemodynamically unstable patients 1

Monitoring During Induction

• Use bispectral index (BIS) monitoring to guide induction and avoid deep levels of anesthesia (BIS < 30), particularly in elderly patients 1
• Monitor hemodynamic parameters closely as higher doses of opioids during induction may cause hypotension 2
• Observe for signs of opioid-induced rigidity, which can be prevented by administering muscle relaxants concurrently 2

Special Considerations

• For patients with obesity: Base induction doses on lean body weight to avoid hypotension 1
• For elderly patients (>60 years): Reduce opioid doses by approximately 25-50% to minimize respiratory depression risk 1
• For opioid-tolerant patients: Higher doses may be required to achieve adequate analgesia 1

Pitfalls and Caveats

• Avoid using long-acting benzodiazepines during induction as they can impair mobilization and cause cognitive dysfunction, especially in elderly patients 1
• Be aware that high doses of remifentanil may induce acute hyperalgesia, potentially requiring higher postoperative analgesic requirements 1
• Muscle rigidity is a potential complication of opioid induction (especially at higher doses), occurring in up to 20% of cases when muscle relaxants are not used concurrently 2
• Respiratory depression is a significant risk with opioid induction; ensure appropriate monitoring and availability of reversal agents 1

Maintenance After Induction

• Continue remifentanil infusion at 0.25-0.48 mcg/kg/min for maintenance of anesthesia 2
• For procedures requiring rapid recovery, maintain with remifentanil rather than longer-acting opioids 1
• Consider opioid-sparing techniques when appropriate to reduce postoperative complications 1

This evidence-based approach to opioid induction balances the need for effective analgesia and hemodynamic stability while minimizing complications and facilitating rapid recovery.