What sedation and paralysis medications are recommended for an unconscious patient post-Return of Spontaneous Circulation (ROSC) in a prehospital setting, with fentanyl or midazolam and rocuronium or succinylcholine available?

Sedation and Paralysis for Post-ROSC Patients in Prehospital Setting

For unconscious post-ROSC patients requiring prehospital intubation with your available medications, use fentanyl (25-100 μg bolus) as the primary sedative-analgesic agent, combined with either rocuronium (0.9-1.2 mg/kg) or succinylcholine (1.0-1.5 mg/kg) for paralysis, with rocuronium being the safer choice if time permits. 1, 2

Sedation Strategy: Analgesic-First Approach

Primary sedation should utilize fentanyl as the cornerstone agent for post-ROSC patients, following the European Heart Journal's recommendation for an analgesic-first approach in cardiac arrest patients. 1

Fentanyl Dosing Protocol

• Initial bolus: 25-100 μg (0.5-2 μg/kg) administered slowly 1
• Maintenance infusion: 25-300 μg/h (0.5-5 μg/kg/h) if transport time allows 1
• Duration of action: 1-4 hours, providing adequate coverage for most prehospital transports 1
• Key advantage: Potent analgesic with anti-shivering effects, critical for post-cardiac arrest patients who may undergo targeted temperature management 1

When to Add Midazolam

Midazolam should be reserved as a secondary agent only if fentanyl alone provides inadequate sedation. 1 The American Heart Association guidelines emphasize that sedation should be titrated cautiously in post-ROSC patients. 1

• Dosing if needed: 2-5 mg (0.01-0.05 mg/kg) bolus, followed by 1-8 mg/h infusion 1, 3
• Critical limitation: Midazolam has active metabolites, is highly deliriogenic, causes delayed awakening, and can accumulate in kidney dysfunction—all significant concerns in post-cardiac arrest patients 1
• Important caveat: The combination of fentanyl and midazolam significantly increases respiratory depression risk compared to either agent alone 1, 3

Paralytic Selection: Rocuronium vs. Succinylcholine

Rocuronium is the Preferred Choice

Rocuronium (0.9-1.2 mg/kg) should be your first-line paralytic for post-ROSC intubation when clinical circumstances allow the 60-90 second onset time. 2, 4

Advantages of Rocuronium:

• Does not increase intracranial pressure, unlike succinylcholine—critical if the arrest had neurologic etiology 2
• No risk of hyperkalemia, which can be catastrophic in post-arrest patients with potential tissue injury 2
• Comparable intubating conditions to succinylcholine when dosed at 0.9-1.2 mg/kg, with 99% achieving excellent/good conditions at 60-90 seconds 5, 4
• Predictable duration of approximately 30-60 minutes depending on dose 5, 4

Critical Pitfall with Rocuronium:

The longer duration of rocuronium (30+ minutes) creates a dangerous window where patients may be awake under paralysis if post-intubation sedation is inadequate. 6, 7 Studies show patients receiving rocuronium receive significantly lower sedation doses at 30 minutes compared to succinylcholine patients (propofol 30 vs 42 μg/kg/min, p=0.002). 6

To prevent awareness under paralysis:

• Administer fentanyl bolus BEFORE rocuronium 2, 8
• Immediately establish continuous fentanyl infusion post-intubation 1, 6
• Consider adding midazolam infusion if transport time exceeds 20 minutes 1, 3

Succinylcholine as Alternative

Succinylcholine (1.0-1.5 mg/kg) remains acceptable when rapid intubation is critical and rocuronium's contraindications are present. 2, 4

Advantages:

• Fastest onset: 50 seconds to complete paralysis 4
• Shortest duration: 10 minutes, reducing awareness risk 6, 7
• Less post-intubation sedation required: Studies show higher sedation doses needed with succinylcholine, suggesting providers naturally compensate for its shorter duration 6, 7

Contraindications in Post-ROSC Context:

• Avoid if hyperkalemia suspected (crush injury, burns, prolonged down time) 2
• Avoid if increased ICP suspected (succinylcholine raises ICP) 2, 3
• Caution with prolonged CPR (tissue breakdown increases hyperkalemia risk) 2

Critical Sequencing for Prehospital RSI

The sequence MUST be: preoxygenation → fentanyl bolus → paralytic → intubation → immediate post-intubation sedation. 2, 8

Step-by-Step Protocol:

1. Preoxygenation: Maximum oxygen delivery via bag-valve-mask 2

2. Fentanyl pretreatment:

   • Administer 1-3 μg/kg (50-200 μg for average adult) 2-3 minutes before paralysis 8
   • This significantly delays awakening signs and attenuates neurovegetative response without hemodynamic compromise 8

3. Paralytic administration:

   • Rocuronium: 0.9-1.2 mg/kg IV push 2, 5
   • OR Succinylcholine: 1.0-1.5 mg/kg IV push 2, 4
   • Wait 60-90 seconds for rocuronium, 45-60 seconds for succinylcholine 5, 4

4. Intubation: Single attempt by most experienced provider 2

5. Immediate post-intubation sedation:

   • Start fentanyl infusion at 25-50 μg/h (0.5-1 μg/kg/h) 1
   • Add midazolam 1-2 mg/h if patient shows signs of awareness or agitation 1, 3

Special Considerations for Post-ROSC Patients

Hemodynamic Monitoring

Post-cardiac arrest patients are exquisitely sensitive to sedative-induced hypotension. 1 Even fentanyl, which is relatively hemodynamically stable, can cause hypotension in this population. 1

• Monitor blood pressure every 2-3 minutes during transport 1
• Have vasopressors immediately available (push-dose epinephrine or norepinephrine) 2
• Reduce sedation doses by 25-50% if systolic BP drops below 90 mmHg 1

Neurologic Assessment Limitations

Recognize that any sedation will obscure neurologic examination, but this is acceptable in the prehospital phase. 1 The American Heart Association explicitly states that aggressive post-ROSC care should not be withheld due to inability to assess neurologic status immediately. 1

• Document initial GCS before sedation 1
• Note pupillary response before paralysis 1
• Communicate to receiving facility that neurologic exam is confounded by sedation 1

Avoid Neuromuscular Blockade Duration Pitfalls

The American Heart Association strongly recommends minimizing neuromuscular blocker duration or avoiding altogether after initial intubation. 1

• Do NOT give additional paralytic doses during transport unless absolutely necessary for ventilator synchrony 1
• If patient "fights" the ventilator, increase sedation rather than adding paralysis 1
• Prolonged paralysis masks seizures, which are common post-arrest 1

Medication Combinations to Avoid

Never combine midazolam and fentanyl without extreme caution and reduced dosing of both agents. 1, 3 The combination produces synergistic respiratory depression:

• Fentanyl alone: 50% hypoxemia rate in volunteers 1
• Benzodiazepine alone: No significant respiratory depression 1
• Combined: Markedly increased respiratory depression requiring 50% dose reduction of each agent 3

Do not use midazolam as sole sedative with rocuronium—the amnestic effect without adequate analgesia creates a situation where patients may experience pain but not remember it, which is ethically problematic. 1, 3

Practical Prehospital Algorithm

For the typical unconscious post-ROSC patient requiring intubation:

1. If GCS ≤8 and no gag reflex: Consider intubation without paralysis using fentanyl 50-100 μg alone 1

2. If paralysis required and no contraindications:

   • Give fentanyl 100-200 μg IV push 8
   • Wait 2 minutes 8
   • Give rocuronium 1.0 mg/kg (∼70-100 mg for average adult) 5
   • Wait 60-90 seconds 5
   • Intubate 5
   • Immediately start fentanyl 50 μg/h infusion 1

3. If rapid sequence critical (active vomiting, severe hypoxemia):

   • Give fentanyl 50-100 μg IV push 8
   • Immediately give succinylcholine 1.5 mg/kg 4
   • Wait 45-60 seconds 4
   • Intubate 4
   • Start fentanyl 50 μg/h infusion 1

4. If inadequate sedation during transport (tachycardia, hypertension, patient movement):

   • Increase fentanyl infusion by 25-50% 1
   • If still inadequate, add midazolam 2 mg bolus, then 1-2 mg/h infusion 1, 3