What medications are recommended for anesthesia, amnesia, and neuromuscular blockade?

Medications for Anesthesia, Amnesia, and Neuromuscular Blockade

For general anesthesia requiring amnesia and neuromuscular blockade, use propofol 2 mg/kg IV for induction, rocuronium 0.6 mg/kg for neuromuscular blockade, and reverse with neostigmine 40-50 mcg/kg only after observing four responses to train-of-four stimulation. 1, 2

Induction and Amnesia

Propofol is the standard medication for induction of general anesthesia due to its rapid onset, quick recovery, and reduced nausea and vomiting compared to alternatives 1. The typical induction dose is 2 mg/kg IV, which produces sleep rapidly with onset in approximately 2 minutes 2, 3.

Enhancing Amnesia with Midazolam

• Administer midazolam 2 mg IV prior to propofol to reduce the risk of intraoperative awareness and decrease propofol requirements by approximately 25-40% 2, 4, 5
• This co-induction technique provides reliable amnesia without significantly delaying recovery in healthy adults 5
• Midazolam doses above 2 mg (such as 5 mg) may delay discharge by approximately 20 minutes in ambulatory patients 5
• The combination of midazolam with propofol is now widely practiced and represents the principal technique for day-case anesthesia 5

Maintenance of Anesthesia

• Either volatile anesthetic gases (sevoflurane) or total intravenous anesthesia (TIVA) with propofol are acceptable for maintenance, as there is no strong data supporting one over the other 1
• Avoid nitrous oxide due to high risk of postoperative nausea/vomiting and delayed return of bowel function 1
• Consider adding dexmedetomidine or ketamine to propofol for effective TIVA, with the added benefit of reduced opioid requirements 1

Neuromuscular Blockade

Rocuronium 0.6 mg/kg is the preferred non-depolarizing neuromuscular blocker for facilitating intubation and providing muscle relaxation 1, 2. This dose provides:

• Onset time of approximately 2 minutes 2
• Surgical paralysis for 20-30 minutes 3
• Predictable reversal characteristics 6

Alternative Neuromuscular Blockers

• Cisatracurium 0.2 mg/kg (2 x ED95) is an excellent alternative, particularly in patients with renal or hepatic disease due to organ-independent metabolism 7
• Vecuronium 0.1 mg/kg provides similar onset (2 minutes) and duration (20 minutes) with excellent cardiovascular stability 3
• Atracurium 0.6 mg/kg offers organ-independent metabolism but may cause localized histamine release 3

Critical Monitoring Requirements

Neuromuscular function MUST be monitored quantitatively using a peripheral nerve stimulator at the hand muscles (not facial muscles) whenever any neuromuscular blocker is administered 1, 8. This is the only method of assuring satisfactory recovery with train-of-four ratio ≥ 0.90 1.

Reversal of Neuromuscular Blockade

Neostigmine is the standard reversal agent for non-depolarizing neuromuscular blockers and must be administered according to specific criteria 1, 8.

Timing of Reversal Administration

Wait for spontaneous recovery to at least four tactile responses to train-of-four stimulation before administering neostigmine 1, 8. This corresponds to a measured TOF ratio of approximately 0.2 1.

• With propofol maintenance: neostigmine 70 mcg/kg after four TOF responses produces complete reversal (TOF ratio >0.9) in less than 10 minutes in all patients 1
• With sevoflurane maintenance: only 55% of patients achieve complete reversal within 10 minutes, requiring longer observation 1
• Administering neostigmine at one or two TOF responses results in incomplete reversal in 60-70% of patients even after 20 minutes 1

Optimal Neostigmine Dosing

Administer neostigmine 40-50 mcg/kg (based on ideal body weight) with neuromuscular monitoring at the adductor pollicis 1. Key principles:

• Do not increase the dose beyond 50 mcg/kg due to a ceiling effect—higher doses do not accelerate reversal 1
• Do not administer neostigmine in the absence of residual blockade (TOF ratio already 1.0), as this causes upper airway obstruction and impaired respiratory function 1
• The dose requirement is similar whether blockade is deep (T1/T0 = 0.01) or moderate (T1/T0 = 0.1), confirming that 40-50 mcg/kg is appropriate across blockade depths 1

Common Pitfalls to Avoid

• Never administer neostigmine before observing four TOF responses—this results in prolonged incomplete reversal requiring extended monitoring 1, 8
• Never skip quantitative neuromuscular monitoring—tactile or visual assessment alone is insufficient to confirm adequate reversal 1, 8
• Never give neostigmine when TOF ratio is already ≥0.9—this paradoxically impairs upper airway patency and respiratory muscle function 1
• Never rely on facial muscle monitoring—hand muscle monitoring at the adductor pollicis is required for accurate assessment 1