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Fentanyl as sole anaesthetic. Stoletings dose

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https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/01…

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Fentanyl as Sole Anaesthetic - "Stoelting Dose"

The term "Stoelting dose" (from Robert K. Stoelting's classic anaesthesia pharmacology textbooks) refers to the high-dose fentanyl technique used as a sole (primary) anaesthetic, almost exclusively for cardiac surgery and high-risk patients.

Dose Tiers (FDA Classification)

TierDoseContext
Low (analgesic supplement)2 mcg/kgMinor surgery, spontaneous respiration
Moderate2-20 mcg/kgMajor surgery, ventilation required
High (anaesthetic dose)20-50 mcg/kgOpen heart, complex neuro/ortho surgery
Sole anaesthetic / Stoelting50-150 mcg/kgHigh-risk cardiac - cardiovascular stability paramount
The FDA label specifies that for use as a general anaesthetic (sole agent), the dose is 50-150 mcg/kg IV, titrated slowly.

Key Pharmacological Rationale

  • At doses above ~15-20 mcg/kg, fentanyl abolishes the sympathoadrenal stress response to surgical stimulation
  • It provides profound cardiovascular stability - no direct myocardial depression, minimal histamine release, no vasodilation
  • Fentanyl does NOT reliably produce unconsciousness or amnesia even at very high doses - this is its major limitation as a sole agent
  • Therefore, even with the "sole anaesthetic" technique, an oxygen +/- N2O background and often a benzodiazepine (midazolam) are typically added to ensure amnesia

High-Dose Fentanyl Cardiac Technique (Miller's Anesthesia, 10e)

  • Induction: Slow IV bolus or infusion of 5-75 mcg/kg to achieve plasma concentrations of 10-30 ng/mL
  • Maintenance infusion: 0.1-1.0 mcg/kg/min through and after CPB
  • Pediatric cardiac: 25-50 mcg/kg combined with isoflurane 0.2-0.4% is sufficient to obtund hemodynamic and stress responses in pre-CPB phase
From Morgan and Mikhail's Clinical Anesthesiology, 7e, Table 10-3:
Fentanyl for intraoperative anaesthesia: 2-50 mcg/kg IV

Critical Points

  1. Mandatory IPPV - Any dose >200 mcg (or >2 mcg/kg) requires controlled mechanical ventilation
  2. Amnesia gap - Fentanyl does not guarantee amnesia; always supplement with a benzodiazepine or low-dose volatile agent
  3. Chest wall rigidity - High bolus doses cause thoracic/abdominal muscle rigidity ("wooden chest") requiring a neuromuscular blocking agent
  4. Prolonged ventilation - Post-op ventilatory support is mandatory after doses >10 mcg/kg; with 50-150 mcg/kg doses, patients remain ventilated in ICU for 12-24+ hours
  5. Opioid-induced hyperalgesia - Can paradoxically worsen post-op pain with very high intraoperative doses

Practical Administration (as Sole Anaesthetic)

  1. Premedicate with midazolam (for amnesia)
  2. Administer fentanyl slowly IV (over 5-10 min) at 50-150 mcg/kg
  3. Observe for loss of eyelash reflex, then give full dose of neuromuscular blocker
  4. Maintain with fentanyl infusion + O2 (100%) +/- N2O (50%)
  5. Plan for post-operative mechanical ventilation
Sources: Miller's Anesthesia, 10e, p. 2842-2843; Morgan & Mikhail's Clinical Anesthesiology, 7e, Table 10-3; FDA Fentanyl Citrate labeling.
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