What are the key considerations for a patient undergoing a procedure requiring monitored anesthesia care (MAC), including pre-procedure evaluation, anesthesia management, and post-procedure monitoring?

Monitored Anesthesia Care: Key Considerations

For patients undergoing procedures with MAC, an appropriately trained anesthesia provider must remain continuously present throughout the entire procedure, with mandatory monitoring including ECG, pulse oximetry, non-invasive blood pressure, and waveform capnography whenever there is loss of verbal responsiveness. 1

Pre-Procedure Evaluation

Essential Patient Assessment

Conduct a focused evaluation targeting specific risk factors that directly impact MAC safety:

• Airway assessment: Identify obesity, history of snoring or obstructive sleep apnea (OSA), cervical spine instability, genetic syndromes with airway implications, and physical abnormalities that increase obstruction risk 1
• Cardiovascular status: Document coronary artery disease, heart failure, arrhythmias, and current cardiac medications 1, 2
• Respiratory function: Screen for OSA symptoms (children with severe OSA have altered mu receptors and increased complication risk), chronic lung disease, and history of prematurity (associated with apnea propensity) 1
• Medication review: Document all prescription drugs, over-the-counter medications, and herbal supplements (St John's wort, ginkgo, ginger, ginseng, garlic can alter drug pharmacokinetics through cytochrome P450 inhibition) 1
• Drug allergies and adverse reactions: Specifically document previous responses to sedatives and analgesics 1
• Pregnancy status: Check menarchal females (up to 1% presenting for anesthesia are pregnant) due to fetal risks from sedating drugs 1

Critical Pitfall to Avoid

Patients with significant OSA require opioid doses reduced to one-third to one-half of standard dosing and may benefit from higher-level care by an anesthesiologist rather than standard MAC. 1

Anesthesia Management

Personnel Requirements

An anesthesia provider must be present continuously throughout MAC—this is non-negotiable. 1, 3 The provider must be familiar with the procedure type, patient comorbidities, and prepared for potential conversion to general anesthesia. 3

Monitoring Standards

Minimum mandatory monitoring for all MAC cases: 1

• ECG (continuous)
• Pulse oximetry with plethysmograph (continuous)
• Non-invasive blood pressure (at minimum every 5 minutes)
• Waveform capnography (mandatory whenever there is loss of response to verbal contact) 1, 4
• Temperature (before procedure and every 30 minutes) 1

Set alarm limits to patient-specific values before initiating sedation and enable audible alarms. 1

Sedation Technique and Drug Administration

For propofol-based MAC (FDA-approved regimen): 5

Initiation:

• Slow infusion method: 100-150 mcg/kg/min for 3-5 minutes, titrated to effect 5
• Slow injection method: 0.5 mg/kg administered over 3-5 minutes 5
• Never use rapid bolus administration—this causes undesirable cardiorespiratory depression including hypotension, apnea, airway obstruction, and oxygen desaturation 5

Maintenance:

• Variable rate infusion: 25-75 mcg/kg/min (most patients) 5
• First 10-15 minutes may require higher rates (up to 75 mcg/kg/min), then decrease to 25-50 mcg/kg/min 5
• Allow approximately 2 minutes for peak drug effect before additional titration 5
• Always titrate downward in absence of light sedation signs to avoid excessive administration 5

Special populations (elderly, debilitated, ASA-PS III or IV):

• Reduce propofol dosage to approximately 80% of usual adult dose 5
• Absolutely avoid rapid bolus administration 5
• Administer over 3-5 minutes minimum 5

Critical Safety Considerations

MAC "aware" (deep sedation) requires identical monitoring intensity to general anesthesia because patients become completely unresponsive to verbal stimuli. 4 Do not reduce monitoring simply because the technique is labeled "MAC." 4

Respiratory events are more common with MAC than general anesthesia, but hypotension is significantly less frequent (14% vs 59% with GA) and briefer (1 minute vs 4 minutes with GA). 1, 4

Documentation Requirements

Maintain time-based records documenting: 1

• All drug names, routes, sites, times, dosages per kilogram, and patient effects 1
• Vital signs (heart rate, blood pressure, SpO₂, ETCO₂) at minimum every 5 minutes 1
• Level of consciousness and responsiveness 1
• Any complications and interventions 3
• Use automated electronic anesthetic record systems when available 1

Perform a "time out" before sedation to confirm patient identity, procedure, and laterality/site. 1

Post-Procedure Monitoring

Recovery Standards

Continue all monitoring through recovery until the patient is fully responsive and predetermined discharge criteria are met. 1, 3

Specific monitoring requirements during recovery: 1

• Maintain continuous monitoring of level of consciousness, heart rate, blood pressure, respiratory rate, oxygen saturation, and expired CO₂ values 1
• If an artificial airway remains in place, continue capnography until the airway is removed AND response to verbal contact is re-established 1
• Document vital signs at appropriate intervals until discharge criteria met 1

Special Consideration for Opioid Administration

Avoid codeine for post-procedure analgesia—some patients have duplicated cytochromes causing greater-than-expected conversion to morphine, resulting in potential overdose. 1 This is particularly dangerous in children with OSA undergoing procedures like tonsillectomy. 1

Transfer Requirements

If transferring a sedated patient with an airway device in place, maintain ECG, SpO₂, NIBP, and capnography monitoring throughout the entire transfer. 1