Recommended Intubation Doses for 18-Year-Old, 178cm, 107kg Patient
For this patient with BMI 33.8 kg/m², administer succinylcholine 107 mg (1.0 mg/kg based on actual body weight), propofol 214-268 mg (2.0-2.5 mg/kg), and fentanyl 107-214 mcg (1-2 mcg/kg).
Succinylcholine Dosing
The guideline-recommended dose is 1.0 mg/kg based on actual body weight, which equals 107 mg for this patient 1. This is particularly important because:
- Suxamethonium provides excellent intubating conditions when dosed at 1.0 mg/kg actual body weight, giving maximum blockade with reproducible intubating conditions 1
- The vocal cords will be open and motionless, and laryngoscope insertion occurs without resistance 1
- Using ideal or lean body mass calculations may result in poor intubation conditions with resistance to laryngoscope introduction and diaphragmatic/limb movement 1
Alternative Lower Dosing (If Rapid Recovery Needed)
If you need faster return of spontaneous ventilation, 0.5-0.6 mg/kg (54-64 mg) provides acceptable intubating conditions in 92-95% of patients at 60 seconds 2, 3. However, this comes with trade-offs:
- Lower doses mean less predictable intubation conditions 2
- The standard 1.0 mg/kg dose represents only 3.5-4 times the ED95, not an excessive amount 4
- Duration of action is dose-dependent; lower doses allow more rapid return of spontaneous respiration 2, 4
Propofol Dosing
Administer 2.0-2.5 mg/kg propofol (214-268 mg) for induction 1. The evidence supports:
- Propofol is the hypnotic of choice for intubation, with rapidly reversible action allowing return of spontaneous ventilation if intubation fails 1
- Studies using 2 mg/kg propofol with fentanyl and succinylcholine achieved 100% successful intubation 2, 5
- In younger patients without significant comorbidities, doses up to 2.5 mg/kg are appropriate 6
Critical Dosing Considerations
- Avoid rapid bolus administration in a single dose; use slower administration (approximately 20 mg every 10 seconds) to prevent significant hypotension 6
- The FDA label warns that rapid bolus can cause undesirable cardiorespiratory depression including hypotension and apnea 6
Fentanyl Dosing
Administer 1-2 mcg/kg fentanyl (107-214 mcg) prior to induction 1. The rationale:
- Short-acting opioids improve intubating conditions but carry higher risk of prolonging apnea 1
- Research protocols successfully used 2 mcg/kg fentanyl with propofol and succinylcholine 2, 3
- Lower doses (1 mcg/kg) also provide adequate conditions when combined with propofol 5
Timing Sequence
Follow this algorithmic approach:
- Pre-oxygenate for 2-3 minutes with 100% oxygen 7
- Administer fentanyl 107-214 mcg IV 2, 3
- Administer propofol 214-268 mg IV slowly (over 20-30 seconds) 6
- Immediately after loss of consciousness, administer succinylcholine 107 mg IV 1
- Intubate at 60 seconds after succinylcholine administration 1, 2
Critical Safety Considerations
Contraindications to Succinylcholine
Do not use succinylcholine if the patient has: 8
- History of malignant hyperthermia (absolute contraindication) 8
- Known myopathy or muscular dystrophy 8
- Immobilization >3 days 8
- Burns or crush injuries 8
- Spinal cord injuries 8
If contraindicated, use rocuronium 0.9-1.2 mg/kg (96-128 mg) instead, with sugammadex immediately available for reversal 8
Monitoring Requirements
- Have dantrolene immediately available wherever succinylcholine is used 8
- Monitor for bradycardia, especially with repeat dosing; have atropine ready 8, 9
- Quantitatively monitor neuromuscular blockade with TOF monitoring 1
Common Pitfalls to Avoid
- Do not calculate succinylcholine dose based on ideal or lean body weight in this patient—use actual weight 1
- Do not administer propofol as a rapid single bolus—this causes severe hypotension 6
- Do not delay intubation beyond 60 seconds after succinylcholine—optimal conditions occur at 60 seconds 2, 3
- Do not use doses >1.5 mg/kg succinylcholine—no additional benefit and prolonged blockade 3