What are the typical anesthesia drugs and doses used for induction and maintenance?

Anesthesia Drugs and Doses

Induction Agents

For intravenous induction, propofol is the primary agent of choice, administered at 2 mg/kg for standard patients, with reduced doses of 0.5-1.5 mg/kg for elderly, debilitated, or ASA III-IV patients using slow administration at approximately 20 mg every 10 seconds. 1, 2

Propofol Dosing

• Standard induction: 2 mg/kg IV 3, 1
• Elderly/compromised patients: 0.5-1.5 mg/kg administered slowly (20 mg every 10 seconds) to avoid hypotension and apnea 2
• Pediatric induction: Dosing based on weight, typically 2-3 mg/kg 1
• Avoid rapid bolus in high-risk patients as this causes significant cardiorespiratory depression 2

Alternative Induction Agents

• Etomidate: Provides hemodynamic stability in unstable patients, particularly useful when propofol's hypotensive effects are concerning 1, 4
• Ketamine: Produces sympathomimetic effects with dose-dependent increases in heart rate and blood pressure; useful in hemodynamically unstable patients 1, 4
• Thiopental: Rapid-acting barbiturate, though less commonly used than propofol 1

Inhalational Induction

• Sevoflurane 7%: Preferred for inhalational induction due to rapid onset and less airway irritation, though insertion time is longer than propofol (115 seconds vs 252 seconds) 4, 5
• Particularly useful in elderly patients where inhalational induction may be better tolerated 1

Neuromuscular Blocking Agents

Rapid Sequence Induction

• Succinylcholine: 1-2 mg/kg for rapid sequence induction and intubation 1, 6
• Rocuronium: 0.9-1.2 mg/kg as alternative to succinylcholine for rapid sequence; can be reversed with sugammadex 1, 6

Standard Intubation

• Rocuronium: 0.6 mg/kg for standard intubation 3, 1
• Additional doses of 0.2 mg/kg as needed during maintenance 3
• Vecuronium and cisatracurium: Alternative non-depolarizing agents 4

Maintenance Agents

Volatile Anesthetics

• Desflurane: Offers faster wake-up times compared to sevoflurane or isoflurane in patients with BMI ≥30 kg/m², but may cause airway irritation and hemodynamic instability 3
• Sevoflurane: 0.3-1.5 MAC with bronchodilator effects; preferred when airway reactivity is a concern 3, 6
• Isoflurane: 0.4-1.5 MAC, though slower offset than desflurane 3, 6

Total Intravenous Anesthesia (TIVA)

• Propofol maintenance infusion:
  • Adults: 100-200 mcg/kg/min (50-100 mcg/kg/min after initial 30 minutes) 2
  • Pediatrics: 200-300 mcg/kg/min initially, then 125-150 mcg/kg/min 2
  • Indian population study showed lower maintenance doses of 81 mcg/kg/min may be adequate 7
• TIVA with propofol may reduce postoperative nausea and vomiting compared to volatile agents 6

Maintenance Combinations

• Propofol 100-200 mcg/kg/min + nitrous oxide 60-70% for general surgery 2
• Sevoflurane or desflurane in oxygen-enriched air as alternative to TIVA 6

Opioid Analgesics

Short-Acting Opioids for Induction/Maintenance

• Fentanyl:
  • Induction: 5 mcg/kg 3
  • Maintenance boluses: 2 mcg/kg as needed 3
  • Infusion: 25-300 mcg/h (0.5-5 mcg/kg/h) 3
• Remifentanil:
  • Induction: 0.5-1 mcg/kg/min infusion 8
  • Maintenance: 0.05-2 mcg/kg/min depending on co-administered agents 8
  • Ultra-short duration ideal for rapid recovery 1
• Alfentanil: Alternative short-acting opioid 1

Opioid-Sparing Alternatives

• Lidocaine, dexmedetomidine, ketamine, and magnesium as part of opioid-free anesthesia may provide better anti-inflammatory effects 3

Sedation Agents

Monitored Anesthesia Care (MAC)

• Propofol infusion: 25-75 mcg/kg/min for MAC sedation in adults 2
• Initiation: 100-150 mcg/kg/min for 3-5 minutes, then titrate down 2
• Avoid rapid bolus in elderly or ASA III-IV patients 2

ICU/Post-Cardiac Arrest Sedation

• Fentanyl bolus + infusion as analgesic-first approach 3
• Dexmedetomidine infusion: Added if inadequate sedation with analgesic alone; has anti-adrenergic effects causing hypotension and bradycardia 3
• Propofol: Short-acting sedative option, though higher risk of hypotension 3
• Midazolam: 2-5 mg bolus or 1-8 mg/h infusion; highly deliriogenic with delayed awakening 3

Depth of Anesthesia Monitoring

Bispectral index (BIS) monitoring should target approximately 50 in elderly patients to reduce postoperative delirium, avoiding deep levels (BIS <30). 3, 6

• BIS or end-tidal anesthetic gas (ETAG) monitoring reduces intraoperative awareness compared to clinical signs alone 3
• Particularly important in obese patients who have increased risk of awareness 3

Special Considerations

Obese Patients

• Induction dosing: Base on lean body weight to avoid hypotension 3
• Maintenance infusion: Use total body weight 3
• Use short-acting agents and multimodal opioid-sparing analgesia 3
• Desflurane or sevoflurane preferred over isoflurane for faster offset 3

Elderly Patients

• Reduce induction doses due to altered pharmacokinetics 1
• Target lighter anesthesia depth (BIS 50 vs 35) to reduce delirium 1, 6
• Avoid excessive opioid doses due to respiratory depression risk 6

Emergency/Rapid Sequence

• Succinylcholine 1-2 mg/kg OR rocuronium 0.9-1.2 mg/kg for fast-acting muscle relaxation 1, 6
• Pre-oxygenation essential before induction 4
• Cricoid pressure during induction, released if it impairs laryngoscopy 4

Common Pitfalls

• Rapid bolus administration in elderly or compromised patients causes severe hypotension, apnea, and oxygen desaturation 2
• Inadequate neuromuscular monitoring risks incomplete reversal before extubation; use quantitative monitoring 6
• Excessive anesthetic depth (BIS <30) increases postoperative delirium and hypotension, especially in elderly 6
• High-dose opioid technique with propofol increases likelihood of hypotension in cardiac anesthesia 2