What is a recommended dosage of Ativan (lorazepam) for a patient undergoing a Magnetic Resonance Imaging (MRI) procedure?

Lorazepam Dosing for MRI Sedation in Adults

For adult patients requiring anxiolysis for MRI procedures, administer lorazepam 0.5-2 mg orally 30-60 minutes prior to the scan, with 1 mg being the most commonly effective starting dose.

Recommended Dosing Strategy

• Start with 1 mg oral lorazepam given 30-60 minutes before the MRI procedure for most adult patients with claustrophobia or anxiety 1
• The dose range of 0.5-2 mg is appropriate depending on patient factors including age, weight, prior benzodiazepine exposure, and anxiety severity 1
• Elderly patients require dose reduction due to decreased drug metabolism and higher risk of respiratory depression; start with 0.5 mg in patients over 65 years 2

Route of Administration Considerations

• Oral administration is the preferred route for pre-procedural anxiolysis in alert, cooperative patients undergoing non-emergent imaging 1, 2
• IV lorazepam (0.5-1 mg administered slowly) may be used if the patient is already in the scanner and becomes acutely anxious, though this requires immediate IV access and monitoring capabilities 2
• The oral route should never be used in patients with decreased responsiveness due to aspiration risk 3, 2

Critical Safety Monitoring Requirements

• Continuous oxygen saturation monitoring is mandatory throughout the procedure and recovery period 3, 4, 2
• Respiratory support equipment must be immediately available, as benzodiazepines carry increased risk of apnea, particularly when combined with other sedatives 3, 4, 2
• Monitor for hypotension, especially in elderly or frail patients 4
• Have flumazenil available to reverse life-threatening respiratory depression, though note it will reverse all benzodiazepine effects 3, 2

Important Clinical Pitfalls to Avoid

• Do not combine lorazepam with other sedatives or opioids without anesthesia support present, as this dramatically increases apnea risk 3, 2, 5
• Avoid doses exceeding 2 mg for outpatient MRI procedures, as higher doses increase risk of prolonged sedation and respiratory depression without proportional anxiolytic benefit 1
• Paradoxical agitation occurs in approximately 10% of patients treated with benzodiazepines; if this develops, do not administer additional doses 1
• Ensure adequate time for drug onset (30-60 minutes for oral route) to avoid premature re-dosing 1

Special Population Considerations

• Patients with hepatic impairment require dose reduction as lorazepam undergoes hepatic metabolism 4
• Those with underlying respiratory disease (COPD, sleep apnea) need lower initial doses and more intensive monitoring 4
• Patients with a history of substance dependence may require alternative anxiolytic strategies, as benzodiazepines carry addiction risk with regular use 1, 6

Alternative Agents for Pediatric Patients

The evidence provided focuses primarily on pediatric sedation protocols, which differ substantially from adult anxiolysis. For children requiring MRI sedation, oral diazepam 5-10 mg was used in anxious older children (>5 years) in radiology studies 1, though pentobarbital and chloral hydrate were more commonly employed for deeper sedation in younger pediatric patients 1. These pediatric protocols are not applicable to routine adult pre-MRI anxiolysis.