The pollution of the operating room environment by anesthetic agents had been questioned,
studied and documented in the past. These investigations demonstrated the existence of
teratogenic effects in animals and the possibility of a decrease in mental performance,
reduced fertility, fetal loss, spontaneous abortion and addictive potential in humans with
chronic exposure to trace amounts of anesthetic agents. These findings led to the
establishment of exposure limits and industry standards by consumer protection agencies,
such as National Institute for Occupational Safety and Health (NIOSH). However, these
standards applied to inhalation anesthetic agents that were excreted from the lungs of
patients during expiration. These concerns about operating room pollution weaned away with
the introduction of intravenous anesthetic agents, such as propofol, because it was believed
propofol was excreted by systems other than the lungs. Recent research points to the
contrary and demonstrates the excretion of propofol vapor in the expired gases of patients.
Furthermore, animal experiments in our laboratory establish the existence of a biological
mechanism responsible for addiction in animals exposed to trace amounts of propofol. We
propose to study the exposure levels of anesthesia care providers in the operating room,
during propofol use, under standardized conditions. Our findings will help to establish
preventive measures for propofol addiction in anesthesia care providers.
This clinical project will be carried out in the operating rooms of the University Hospital
and the Doctors Office Center. The study will be done during routine surgery where a
laryngeal mask airway will be used to maintain airway during general anesthesia in 20 adult
patients with American Society of Anesthesiologists physical status I or II. Routine
anesthetic care standards will be applied in intravenous line placement and monitoring of
patients. General anesthesia will be induced with a bolus dose of propofol (2mg.kg-1) and
maintained with an intravenous infusion of propofol (100-200 mcg.kg-1.min-1). Patients will
be allowed to breathe spontaneously 40% oxygen in air. Adjuvant intravenous medications
will be given for amnesia, analgesia and infection prophylaxis as per routine anesthetic
practice. The ambient propofol concentration will be measured, using a proton transfer
reaction mass spectrometer (PTR-MS), at a distance of 25cm from the patient's face. The
measurement of ambient propofol concentration will begin before the administration of
propofol to the patient and will continue till the patient leaves the operating room. The
use of PTR-MS device will not interfere with the anesthetic management of patient. In an
unforeseen circumstance, where the anesthesiologist determines the use of PTR-MS does
interfere with the anesthetic care of the patient, the device will be immediately removed
and the measurement of ambient propofol concentration will be suspended for the case. The
set-up and usage of PTR-MS will be performed by a research team that does not take part in
the clinical management of the patient. The PTR-MS is a device that depends on the proton
transfer reaction to quantify, in parts per billion (ppb) by volume, volatile organic
compounds in air at extremely low concentrations and in real time. The mean and peak
ambient propofol concentration will be determined during each case and a time weighted
average (TWA) will be calculated for an eight-hour period at the end of the study. In
addition, after receiving written informed consent from anesthesia care providers, blood
samples will be drawn from them and propofol concentrations will be measured by
high-performance liquid chromatography (HPLC) within 24hr. The blood samples will
constitute 3ml on two occasions, one early in the morning before anesthesia care starts and
one after eight hours of anesthesia care. HPLC is a device that uses a spectrofluorometric
detector to estimate trace amounts of propofol in blood in ng.ml-1. The blood estimation of
propofol will also be conducted by a research team that does not take part in the clinical
management of patients.
- If you are over the age of 18- and under 65, and mentally capable of giving consent.
- If you are an Anesthesiology staff member.
- If you are scheduled to administer propofol during general anesthesia and surgery
- If you refuse to sign consent.
- If you are not administering propofol within 8 hours after your first blood draw.
- If you are pregnant.
Ming Xiong, PHD, MD
Rutgers, The State University of New Jersey