This document discusses occupational exposure to waste anesthetic gases. It defines trace anesthetic gases and notes they are a hazard for workers like anesthesiologists, nurses and technicians. It describes how workers are exposed in operating rooms and recovery rooms, especially when ventilation and scavenging systems are inadequate. The document outlines health effects of exposure and recommends work practices and monitoring to minimize risks.

1. TRACE
ANESTHETI
C
EXPOSURE
BY
DR.SANDEEP

2. INTRODUCTION
• Waste anesthetic gases are small amounts of anesthetic gases that
leak from the patient’s anesthetic breathing circuit into the air of
operating rooms during delivery of anesthesia.
• It is an occupational hazard
The purpose of this session is to:
Increase awareness about the adverse health effects of waste
anesthetic gases
 Describe how workers are exposed to waste anesthetic gases
 Recommend work practices to reduce these exposures
 Identify methods to minimize leakage of anesthetic gases into the
work environment

3. TRACE ANESTHETICS / WASTE GASES
DEFINITION:
A trace level of anesthetic gas is a
concentration far below than needed for clinical
anesthesia or that can be detected by smell.
• Usually expressed in PPM, which is volume by volume
(100% of a gas is 10,00,000 ppm ; 1% is 10,000 ppm).

4. WHO IS EXPOSED TO WASTE ANESTHETIC GASES?
The following hospital workers may be exposed to
waste anesthetic gases:
• Anesthesiologists
• Dentists
• Nurse anesthetists
• Operating-room nurses
• Operating-room technicians
• Other operating-room personnel
• Recovery-room nurses
• Other recovery-room personnel
• Surgeons

5. Where are workers most likely to be exposed to
waste anesthetic gases?
Workers are most likely to be exposed to waste anesthetic
gases in
• Operating facilities with no automatic ventilation or scavenging
systems,
• Operating facilities where these systems are in poor condition, or
• Recovery rooms where gases exhaled by recovering patients are
not properly vented or scavenged.

6. Even when scavenging and venting systems are in
place, workers may be exposed to these gases under the
following conditions:
• When leaks occur in the anesthetic breathing circuit (which may leak gas if the
connectors, tubing, and valves are not maintained and tightly connected)
• When anesthetic gases escape during hookup and disconnection of the
system
• When anesthetic gas seeps over the lip of the patient’s mask or from
endotracheal coupling (particularly if the mask is poorly fitted—for
example, during pediatric anesthesia)
• During dental operations
• During induction of anesthesia

7. • WASTE GASES ARE USUALLY
• Nitrous oxide
• Halogenated volatile anesthetics
• Combination of both

8. Concentrations in operating rooms vary greatly and
depends on
• The fresh gas flow,
• The ventilation system,
• The length of time that anesthesia has been administered,
• The measurement site,
• Anesthetic technique,
• And other variables
higher with pediatric anesthesia, in dental operations , and in poorly
ventilated PACU.

9. SITES OF LEAK
• Mask
• Endotracheal tube
• Anesthetic gas machine
• Ventilator
• Pumps
• Scavenging devices
• All connecting tubing
• Other elements- depending on the type of anesthesia delivery
system.

10. CONSEQUENCES

12. CONSEQUENCES
MISCELLANEOUS
• Spontaneous abortion
• Bone and joint disease ,
• Infertility
• Ulcers ,
• Birth defects
• Ulcerative colitis ,
• Impaired performance
• Gallbladder disease ,
• Cancer - Melanoma
• Migraine, and
• Mutagenicity
• Headache and fatigue
• Renal diseases
• Ophthalmic hypersensitivity
• Hematological diseases
• Conjunctivitis
• Neurologic symptoms
• Exacerbation of Myasthenia Gravis
• Cardiac diseases
• Skin eruptions

14. • Liver diseases:-
 Recurrent hepatitis (halothane)
 enhanced hepatic metabolism of some drugs .
 Elevated serum autoantibodies that react with
 specific hepatic proteins,
 especially females and pediatric anesthesiologists.
• Bone marrow abnormalities
• Nonspecific polyneuropathy

15. CONTROL MEASURES
• Complete elimination is impossible.
• Goal is to reduce concentrations to the lowest level with a
reasonable expenditure of effort and money.
• To achieve this, attention should be focused on four areas:
1. Scavenging,
2. Equipment leaks,
3. Work techniques, and
4. The room ventilation system.

16. SCAVENGING SYSTEMS
• Scavenging is the collection of excess gases from equipment used
to administer anesthesia or exhaled by the patient and the removal
of these gases to an appropriate place of discharge outside the
work environment.
• Also referred to as evacuation systems, waste anesthetic gas
disposal systems, anesthesia waste exhaust, and excess anesthetic
gas-scavenging systems.

17. SCAVENGING SYSTEMS
Consists of five basic parts:
• A GAS-COLLECTING ASSEMBLY, which captures gases at the site of
emission;
• A TRANSFER TUBING, which conveys collected gases to the
interface;
• THE INTERFACE, which provides positive (and sometimes negative)
pressure relief and may provide reservoir capacity
• THE GAS-DISPOSAL TUBING, which conducts the gases from the
interface to the gas-disposal system; and
• THE GAS DISPOSAL SYSTEM, which conveys the gases to a point
where they are discharged.

18. PASSIVE SYSTEMS
• Room Ventilation System – non-recirculating and recirculating
• Piping Direct to Atmosphere-direct duct or vent, specialized
duct system, direct disposal line, or through-the-wall system
• Adsorption Device-activated charcoal
• Catalytic Decomposition

19. ROOM VENTILATION SYSTEM
• A NONRECIRCULATING SYSTEM takes in exterior air and
processes it by filtering and adjusting the humidity and
temperature. The processed air is circulated through the
room and then all of it is exhausted to atmosphere
• A CIRCULATING SYSTEM takes a small amount of air is taken
in from the atmosphere, while the remaining air is recirculated

20. VENTILATION SYSTEM
• Install a ventilation system that circulates and replenishes the
air in operating rooms (at least 15 air changes per hour, with a
minimum of 3 air changes of fresh air per hour).
• Install a ventilation system that circulates and replenishes the
air in recovery rooms (at least 6 air changes per hour, with a
minimum of 2 air changes of fresh air per hour) to prevent
exposure to waste anesthetic gases exhaled by patients.

21. PIPING DIRECT TO ATMOSPHERE
• The discharge point on the outside should be selected so that
it is away from wind pressures, ignition
hazards, windows, and the inlets for the ventilation system. It
may be advantageous to attach a short T-piece as a terminal
• THE OPEN end should point downward to prevent water and
dirt from entering and be fitted with netting to prevent
insects, rodents, and foreign matter from entering the pipe.
• PROBLEMS include both positive and negative pressure
caused by wind currents, obstruction from ice build up, and
accumulation of foreign matter at the outlet

22. ADSORPTION
• An adsorption device removes some or all excess anesthetic
agents by adsorbing them or converting them to harmless
substances
Eg: Canisters
• The efficiency of adsorption also depends on the flow rate
through the canister. Moisture may reduce the efficiency
• ADV: Simple and portable, do not require expensive
installation or maintenance, halogenated anesthetic vapors
are not released to the ozone layer
• DIS ADV : No adsorption device for nitrous
oxide, expensive, effective for only short periods of time.

23. ACTIVE SYSTEMS
• Piped Vacuum Systems
• Active Duct System

24. PREVENTIVE MEASURES
1. Checking equipment before use-check for irregularities or breaks
and circuit for negative pressure and positive pressure relief as
part of the daily machine checklist.
2. Turn on the local/ room ventilation system.
3. Using scavenging equipment-make sure the scavenging
equipment is properly connected & connect the gas outlet to the
hospital’s central scavenging system
4. Start the gas flow after the laryngeal mask or endotracheal tube
is installed

25. PREVENTIVE MEASURES
5. Proper use of airway devices-Make sure that uncuffed endotracheal
tubes create a completely sealed airway
6. Using low fresh gas flows-Use the lowest anesthetic gas flow rates
possible for the proper functioning of the anesthesia delivery system
and for patient safety
7. Avoiding insufflation techniques AND HIGH FLOW Rates-rates to
prevent leaks: high flow rates generate more waste anesthetic gases
than low flow rates.
8. Preventing liquid agent spills-Fill vaporizers before or after the
anesthetic procedure [1 mL of a volatile liquid anesthetic = 200 mL of vapour
= 2ppm (closed room measuring 20 by 20 by 9 ft)]

26. PREVENTIVE MEASURES
9. Proper mask fit
10. Washout of a Anesthetic gases at the end of the case-Eliminate
residual gases through the scavenging system as much as
possible before disconnecting a patient from a breathing system
11. Preventing Anesthetic Gas Flow Directly into the Room-Turn the
gas off before turning off the breathing system.
12. Alteratons in work practices

27. PREVENTIVE MEASURES
13. Using intravenous and regional anesthesia
14. Keeping scavenging hoses off the floor
15. Leak control

28. MONITORING
Develop a monitoring program supervised by a
knowledgeable person in every operating facility. Such a
program should include
• Quantitatively evaluating the effectiveness of a waste-gas
control system and
• Repeatedly measuring concentrations of anesthetic gas in the
breathing zones of the most heavily exposed workers while
they perform their usual procedures.
• Keep good records of all collected air sample results for at
least 30 years.

29. MONITORING
• Keep medical records of a worker’s exposure for 30 years
after his or her employment has ended
• Obtain baseline liver and kidney data for operating- room
personnel and monitor their liver and kidney functions
periodically.
• Record medical histories for workers and their
families, including occupational histories and outcomes of all
pregnancies of female workers and wives of male workers (if
possible

30. MONITORNG TRACE GASES
• Air monitoring
• EQUIPMENT:-
• Infrared analyzers
• Proton transfer reaction mass spectrometry
• Dosimeters
• Ionizing leak detectors
• Oxygen analyzer
• Carbon dioxide analyzer

31. SAMPLING METHODS
• Instantaneous sampling
• Sampling at the air conditioning exhaust
• Time weighted average sampling
• Continuous sampling
• Personnel sampling

32. AGENTS TO BE MONITERED
• Nitrous oxide
• Volatile agents

33. SITES TO BE MONITORED
• Monitoring should be scheduled so that the work of each
anesthesia provider and of each operating room is checked while
using a mask, supraglottic device, and tracheal tube.
• Monitoring should be performed during spontaneous, manually
assisted, and manually controlled and automatic ventilation.
• The results of the monitoring should be analyzed and discussed
with all parties concerned

34. OTHER ASPECTS
• Personal Monitoring
• Area (room) sampling
• Monitoring frequency

35. MONITORING FREQUENCY
The following schedule has been suggested :
• An annual comprehensive survey in which exposure levels are
measured, leaks detected and corrected, and TWA exposure levels
are calculated or measured.
• Quarterly follow-up with a less-detailed survey; if there appears to
be a problem, a comprehensive survey should be performed to
determine causes and assess corrective actions.
• A repeat comprehensive survey in the event of major changes to
the ventilation system, anesthesia equipment, or scavenging
systems.
• TWA monitoring of each member of the staff for a short
period, such as a week, repeated on a 6-month basis also has been
suggested

36. MEDICOLEGAL ASPECTS
OCCUPATIONAL SAFETY AND HEALTH ACT(OSHA)
Agencies
The national institute of OSHA
safety and health (NIOSH)
• NIOSH under the department of Health and human services
• OSHA under the department of Labour

37. • NIOSH- conducting and funding research and education and
for preparing criteria documents to be used to develop
standards.
• OSHA - enacting job safety and health standards, establishing
reporting and recordkeeping procedures, inspecting
workplaces, and enforcing the requirements of the act by
using citations and fines.

38. ARBITRARY SAFETY LIMITS
• For Nitrous Oxide alone-exposure limit of 25 ppm
• For halogenated agents used alone, the limit was 2 ppm .
• When halogenated agents are used in combination with Nitrous
Oxide, the recommended limits were 25 ppm nitrous oxide and 0.5
ppm of the halogenated agent
• For dental facilities, a level of 50 ppm Nitrous Oxide was
recommended.
• During mask induction, the level of Sevoflurane should be less than
2 ppm.

39. • The 1970 act gives each employee the right to request an OSHA
inspection if an employee believes that he or she is in imminent
danger from a hazard or if OSHA standards are being violated.
• The American Society of Anesthesiologists (ASA) legal counsel has
advised that it is within the right of an employer to refuse to permit
an OSHA representative to enter the facility unless that individual
has either a search warrant or a court order compelling the
inspection.
• All states have workers' compensation laws so that individuals
suffering from occupational diseases can collect
benefits, irrespective of whether or not the employer's negligence
caused the disease