What is the recommended dosage of lorazepam (Ativan) for Intensive Care Unit (ICU) sedation?

Lorazepam Dosing for ICU Sedation

For ICU sedation, lorazepam should be administered at an initial IV loading dose of 0.02-0.04 mg/kg (maximum 2 mg), followed by maintenance dosing of 0.01-0.1 mg/kg/hr continuous infusion (maximum 10 mg/hr) or 0.02-0.06 mg/kg every 2-6 hours as needed. 1

Pharmacology and Administration

Lorazepam is a benzodiazepine with the following characteristics:

• Onset of action: 15-20 minutes after IV administration
• Elimination half-life: 8-15 hours
• No active metabolites (unlike midazolam and diazepam)
• Loading dose: 0.02-0.04 mg/kg (≤ 2 mg)
• Maintenance dosing options:
  • Continuous infusion: 0.01-0.1 mg/kg/hr (not exceeding 10 mg/hr)
  • Intermittent dosing: 0.02-0.06 mg/kg every 2-6 hours as needed

Efficacy and Clinical Considerations

While lorazepam has traditionally been used for ICU sedation, current evidence suggests that non-benzodiazepine sedatives may offer advantages:

• Propofol vs. lorazepam: Fewer ventilator days (5.8 vs. 8.4 days) 1
• Dexmedetomidine vs. lorazepam: More days alive without delirium or coma (7.0 vs. 3.0 days) 1

Important Adverse Effects

• Respiratory depression and hypotension, particularly when combined with opioids 1
• Propylene glycol-related acidosis and nephrotoxicity with continuous infusion 1
  • Can occur with total daily IV doses as low as 1 mg/kg
  • Monitor osmol gap (>10-12 mOsm/L suggests significant propylene glycol accumulation)
• Delayed emergence from sedation due to:
  • Prolonged administration (tissue saturation)
  • Advanced age
  • Hepatic dysfunction
  • Renal insufficiency 1

Current Recommendations

The 2013 Society of Critical Care Medicine guidelines suggest that non-benzodiazepine sedatives (propofol or dexmedetomidine) may be preferred over benzodiazepines (midazolam or lorazepam) to improve clinical outcomes in mechanically ventilated ICU patients 1. This recommendation is based on evidence showing:

• Shorter ICU length of stay (by approximately 0.5 days)
• Reduced duration of mechanical ventilation
• Lower incidence of delirium

Practical Dosing Algorithm

1. Initial sedation:

   • Loading dose: 0.02-0.04 mg/kg IV (not exceeding 2 mg)
   • Assess response after 15-20 minutes (onset time)

2. Maintenance options:

   • Continuous infusion: Start at 0.01-0.02 mg/kg/hr and titrate to desired effect
   • Intermittent dosing: 0.02-0.06 mg/kg every 2-6 hours as needed

3. Titration:

   • Target light sedation (patient arousable and able to follow simple commands)
   • Use validated sedation scales (e.g., RASS, SAS) to guide dosing
   • Adjust dose every 8 hours if sedation is adequate, or every 2 hours if inadequate 2

4. Maximum dose:

   • Do not exceed 10 mg/hr for continuous infusion 1
   • Consider alternative agents if adequate sedation not achieved at maximum dose

Monitoring

• Assess sedation level using validated scales
• Monitor for respiratory depression and hypotension
• Check for signs of propylene glycol toxicity:
  • Metabolic acidosis
  • Acute kidney injury
  • Elevated osmol gap (>10-12 mOsm/L)
• Evaluate for delayed emergence, particularly with prolonged use

Caution

While lorazepam dosing information is provided as requested, current evidence suggests that non-benzodiazepine sedatives like propofol and dexmedetomidine may be preferred first-line agents for ICU sedation due to improved clinical outcomes including reduced delirium, shorter ventilator days, and potentially decreased mortality 1.