The Relative Exposure of the Operating Room Staff to Sevoflurane During Intracerebral Surgery

Anesth Analg 2009;109:1187-92

Background Volatile anesthetic on staff

Since 1967 Chronic exposure

Hepatotoxicity and nephrotoxicity Carcinogenesis Immunity Fertility Fetal development

More likely to develop Headache Somatic and mental fatigue attention

Potential environment factors Mask induction Uncuffed tracheal tube Laryngeal mask …… Anesthetic from surgical field to the surg

eon?

Neurosurgery The brain

Blood perfusion Capillary network Fat content

Sevoflurane Rapid accumulation in the brain Blood: gas partition coefficient=0.69

Marked escape from blood when circulation open

Questions?

sevoflurane close to the craniotomy window (the surgeon’s breathing zone) remote site in the OR

a correlation? sevoflurane near surgical site size of the cranitomy window

Methods Induction

propofol 1-2.5mg/kg Maintenance

Fentanly-rocuronium-sevoflurane Intubation

Low pressure cuffed <30mmHg

Monitoring

Fresh gas flow 2L/min Sevoflurane (0.7-2.3 V%) Air

Scavenging system Air circulation 50m3/min

Sample collection (dura opening ~ closure ending) 35 patients

Surgeon’s breathing zone Anesthesiologist’s breathing zone Farthest corner of OR

16 patients …… …… Within 5cm of the tracheal tube

Data analysis

Chromatography ppm (one part per million) mean+ SD P<0.05

Results

Sevoflurane release at the patients’ mouth

Sevoflurane exposure at different sites

Craniotomy window and sevoflurane release

As a function of tumor type

Type Concentration(ppm)

n

Meningiomas 0.28+0.20 17

gliomatous 0.19+0.19 20

metastatic 0.20+0.07 9

others 0.19+0.09 5

Others

The ventilation system is good. Different concentrations at different sites For extended surgery

Low concentration Nonsignificant correlation with sevoflurane

OR door opening airflow air clearance

Conclusion Release of sevoflurane from the brain

through the craniotomy window dose not pose an additional environment risk for the neurosurgeon.

We should focus on improving the working condition for anesthesiologists.

We should further explore reasons for sevoflurane escape adequate countermeasures

Effect of Volatile Anesthetics on Oxidative Stress Due to Occupational Exposure

Method 30 anesthesia and surgery personnel

inhalation anesthetics for 3 years 30 healthy volunteers

no exposure at any time Result

antioxidant activity and trace element levels Conclusion

Antioxidant defense system was affected by free radical injury in those exposed to inhalation anesthetics chronically.

So minimizing occupational exposure to volatile anesthetics Operating room personnel should also take antioxidant supple

ments. World Journal of Surgery, 2005,29(4):540-542

Who is exposed? Anesthesiologists Dentists Nurse anesthetists Operating-room nurses Operating-room technicians Other operating-room personnel Recovery-room nurses Other recovery-room personnel Surgeons

What are the health effects? High concentration

Headache Irritability Fatigue Nausea Drowsiness Difficulties with judgement and coordina

tion Liver and kidney disease

Low concentration chronically miscarriages genetic damage cancer miscarriages in spouses birth defects in offspring

Where most likely to be exposed?

no automatic ventilation or scavenging systems

systems are in poor condition recovery rooms where gases exhaled

by recovering patients are not properly vented or scavenged

When leaks breathing circuit disconnection of the system gas seeps over the lip of mask or from en

dotracheal coupling During dental operations During induction of anesthesia

How to reduce? Inspect the anesthetic delivery system befo

re each use as part of the daily machine checklist.

Make sure the scavenging equipment is properly connected.

Start the gas flow after the laryngeal mask or endotracheal tube is installed.

Fill vaporizers under a ceiling-mounted hood with an active evacuation system.

Fill vaporizers before or after the anesthetic procedure.

Make sure that uncuffed endotracheal tubes create a completely sealed airway.

Use the lowest anesthetic gas flow rates possible Do not deliver anesthesia by open drop (drippin

g liquid, volatile anesthetic onto gauze). If a mask is used, make sure it fits the patient wel

l. Eliminate residual gases through the scavenging

system as much as possible before disconnecting a patient from a breathing system.

Turn the gas off before turning off the breathing system.