How can healthcare workers prevent inhalation of sevoflurane (anesthetic gas) in the operating room?

Preventing Healthcare Worker Inhalation of Sevoflurane

Healthcare workers should ensure the anesthetic gas scavenging system is switched on and functioning, with tubing properly attached to the exhaust port of the breathing system, ventilator, or anesthetic workstation before every case. 1

Primary Prevention Strategy: Scavenging Systems

The most fundamental protection against sevoflurane exposure is proper scavenging system operation, as this addresses the source of contamination directly:

• Check scavenging system functionality before each case as part of standard equipment checks, confirming it is switched on and all connections are secure 1
• Verify tubing attachment to the appropriate exhaust port of the breathing system, ventilator, or anesthetic workstation to prevent gas escape into the operating room 1
• Maintain adequate operating room ventilation with positive-pressure ventilation (>15 air changes per hour, with >3 air changes of fresh air) to dilute any residual gases 1

Understanding Why Standard Masks Don't Work

A critical misconception must be addressed: surgical or procedural masks do not filter sevoflurane vapors because they are designed for droplet and particulate transmission, not volatile organic compounds that exist as vapors in ambient air 2. Over 95% of administered sevoflurane is exhaled unmetabolized and released into the operating room atmosphere, making proper scavenging the only effective primary defense 2.

Advanced Exposure Reduction Techniques

Low Fresh Gas Flow

Use low fresh gas flow (≤1 L/min during wash-in and 0.35 L/min during maintenance) to substantially reduce environmental contamination and minimize the amount of sevoflurane requiring scavenging 2, 3. The French Society of Anesthesia and Resuscitation strongly recommends this practice 1, 3.

Activated Charcoal Filters (ACFs)

For situations requiring additional protection (such as malignant hyperthermia-susceptible patients or equipment preparation):

• Place ACFs containing 50 mL of granular activated charcoal on both inspiratory and expiratory limbs of breathing circuits to reduce sevoflurane concentrations to <5 ppm within 2-3 minutes 1, 2
• Maintain ACFs in place during the entire anesthetic procedure to ensure continuous protection 1
• Use minimum fresh gas flow of 1 L/min when ACFs are in place, as this maintains sevoflurane levels <5 ppm over 24 hours 1

Depth of Anesthesia Monitoring

Monitor depth of anesthesia in association with end-tidal anesthetic concentration to reduce overall consumption of anesthetic vapors, thereby decreasing the total amount requiring scavenging 1, 3

Special Situations Requiring Enhanced Precautions

Recovery Room Environment

Recovery units often lack scavenging systems, creating higher exposure risk:

• Use specialized oxygen/scavenging masks (such as ISO-Gard) in the recovery unit, which reduce exhaled sevoflurane levels by ~90% in the patient breathing zone and 78% in the nurse work zone within 20 seconds of application 4
• Position the scavenging inlet close to the patient's breathing region (nose and mouth) in the front direction to optimize capture efficiency 5

Cardiopulmonary Bypass

During cardiac surgery with cardiopulmonary bypass, ensure adequate operating room ventilation and waste gas scavenging as sevoflurane concentrations can accumulate at multiple sites (oxygenator outlet, cardiotomy reservoir outlet, perfusionist breathing zone) 6.

Intensive Care Unit Sedation

When using sevoflurane via AnaConDa® devices for ICU sedation:

• Apply gas extraction systems to the ventilator or use scavenging devices such as CONTRAfluran™ to reduce occupational exposure below 2 ppm 7
• Implement these systems even though baseline exposure may be acceptable, as they provide an additional safety margin 7

Common Pitfalls to Avoid

• Never assume surgical masks provide protection against volatile anesthetic gases—they do not filter vapors 2
• Do not neglect scavenging system checks during pre-anesthetic equipment verification, as gas monitoring lines and scavenging connections are frequent sources of leaks 1
• Avoid high fresh gas flows when not clinically necessary, as this increases both environmental impact and workplace exposure 1, 2, 3
• Do not remove ACFs prematurely if using them—they must remain in place for the entire procedure to maintain concentrations <5 ppm 1

Verification of Adequate Protection

Target workplace exposure levels should remain below 2 ppm (the NIOSH recommended time-weighted average for sevoflurane) 7, 5. When proper scavenging, ventilation, and low fresh gas flow techniques are employed, measured concentrations typically range from 0.06-8.7 ppm for various anesthetic gases, well within safety limits 6, 5.