What medications are recommended for muscle relaxation in an adult patient with no significant medical history for reduction of an open fracture?

Medication for Muscle Relaxation in Open Fracture Reduction

For open fracture reduction in adults, propofol (1 mg/kg initial dose with 0.5 mg/kg supplemental dosing) combined with an opioid analgesic is the recommended agent for procedural sedation and muscle relaxation, as it provides safe and effective conditions for fracture reduction with rapid onset and recovery. 1

Primary Sedation Options for Fracture Reduction

Propofol-Based Sedation (First-Line)

• Propofol is safe and effective when administered by emergency physicians for procedural sedation in fracture reduction, with an initial dose of 1 mg/kg followed by 0.5 mg/kg supplemental doses as needed 1
• Oxygen saturation was maintained >90% in 95% of patients, with median hypoxia duration of 1-3 minutes and no patients requiring intubation 1
• All procedures were completed successfully with this regimen 1
• Propofol combined with morphine for pain control demonstrated equal efficacy to methohexital, with a respiratory depression rate of 49% (which resolved without intervention) and a bispectral index (BIS) of 66, indicating appropriate sedation depth 1

Ketamine-Based Sedation (Alternative Option)

• IV ketamine at 1.5-2 mg/kg provides adequate sedation for fracture reduction with rapid onset (96 seconds average) and all patients achieving adequate sedation 1
• For pediatric patients aged 12 months to 11 years, IV ketamine 2 mg/kg or IM ketamine 4 mg/kg allowed adequate sedation for fracture/joint reduction without serious adverse effects 1
• Ketamine may be associated with postoperative confusion in elderly patients and should be used cautiously in this population 1
• Adding midazolam to ketamine does not decrease recovery agitation and may increase it in patients >10 years old, though it reduces emesis 1

Benzodiazepine-Opioid Combinations

• Diazepam 0.1 mg/kg plus fentanyl 1 μg/kg IV provides superior onset of muscle relaxation and time to reduction compared to midazolam plus fentanyl for shoulder dislocation reduction 2
• Midazolam 0.1 mg/kg plus fentanyl 1 μg/kg IV is an alternative, though with longer onset time 2

Neuromuscular Blocking Agents (For Operating Room Use)

When General Anesthesia is Required

• Rocuronium bromide 0.6 mg/kg provides excellent to good intubating conditions within 2 minutes and clinical relaxation for a median of 33 minutes under opioid/nitrous oxide/oxygen anesthesia 3
• For rapid sequence intubation, rocuronium 0.6 mg/kg achieved excellent or good intubating conditions in 99% of patients when intubation was attempted within 60-90 seconds 3
• Rocuronium should be dosed according to actual body weight in obese patients, as dosing by ideal body weight results in longer time to maximum block and inadequate intubating conditions 3
• Neuromuscular block is readily reversed with anticholinesterase agents (neostigmine 0.04 mg/kg or edrophonium 0.5 mg/kg) once spontaneous recovery reaches 25% of control 3

Succinylcholine Considerations

• Succinylcholine at 1 mg/kg based on actual body weight provides excellent intubating conditions in obese patients 1
• For patients at risk for complications from inadequate muscle relaxation (such as recent hip fracture repair), succinylcholine dose may need to be increased by 40-50% to ensure complete relaxation 4

Anesthetic Technique Selection

Regional vs. General Anesthesia

• Either spinal anesthesia or general anesthesia is recommended for open fracture surgery, but simultaneous administration is associated with precipitous falls in blood pressure 1
• Lower doses of intrathecal bupivacaine (<10 mg) reduce associated hypotension in elderly patients 1
• Regional anesthesia as part of multi-modal analgesia provides short-term, early recovery benefits for wrist fracture surgery 5
• Peripheral nerve blockade (femoral, obturator, lateral cutaneous nerve) should be considered as an adjunct to reduce postoperative opioid requirements 1

Critical Dosing and Safety Considerations

Propofol Administration

• Optimal sedation occurs with BIS between 70-85, balancing adequate sedation with lower respiratory depression rates 1
• Patients with BIS <70 had higher respiratory depression rates, while those with BIS >85 had higher pain and recall rates 1
• Respiratory depression with propofol is manageable and does not require intubation in the vast majority of cases 1

Ketamine Administration

• IV ketamine 1.5 mg/kg is more effective than 1 mg/kg, with only 5.5% requiring additional dosing compared to 54% with the lower dose 1
• Recovery time for IV ketamine averages 84 minutes, while IM ketamine averages 90 minutes 1
• Ketamine does not induce clinically significant hypoventilation based on end-tidal CO2 monitoring 1

Common Pitfalls to Avoid

• Do not use rocuronium for rapid sequence induction in Cesarean section patients, as intubating conditions were poor or inadequate in 38% of women when lower-dose thiopental was used 3
• Do not administer opioid analgesics as the sole adjunct to anesthesia in elderly patients due to greater risk of respiratory depression and postoperative confusion 1
• Do not dose rocuronium based on ideal body weight in obese patients, as this results in inadequate muscle relaxation 3
• Do not delay antibiotic administration in open fractures—antibiotics should be initiated within 3 hours of injury, as infection rates increase after this time 6
• Ensure continuous monitoring with pulse oximetry, capnography, ECG, and non-invasive blood pressure during all procedural sedation 1