Details of theater pollution and methods to control has been described.

1. Theatre Pollution &
Scavenger system in OR
Dr. P K Maharana.
KIMS, BHUBANESWAR, India.

2. Definition
An anaesthetic gas scavenging system is a system or device that
collects excess anaesthetic gas from the breathing system and
discharges it outside the working environment.
• It is used to collect gases or aerosolized medications from the patient exhalations
or found near the patient area because of some treatment related activities.
Often associated with delivery of anaesthesia but may also include other patient
related activities .

3. Introduction
When patients are administered anaesthetic gas, its molecules escape into the room since the use
of gases and agents exceeds the amount necessary for the patient and can impact the
performance of medical teams.
Inhaled anesthetic agents include two different classes of chemicals: nitrous oxide and
halogenated agents. Halogenated agents currently in use include halothane , enflurane,
isoflurane, desflurane , and sevoflurane .
Since the late 1960s there has been speculation that trace anaesthetic gases/vapours may have a
harmful effect on operating theatre personnel, but it has been conclusively proved from currently
available studies that there is no association between occupational exposure to trace levels of
waste anaesthetic vapours in scavenged operating theatres and adverse health effects. Nitrous
Oxide does some in high concentration.
However, it is desirable to vent out the exhaled anaesthetic vapours and maintain a vapour-free
theatre environment. At present, the Occupational Safety and Health Administration (OSHA) has
no permissible exposure limits regulating these agents.
In the Operating Room the Anaesthetic Gas Scavenging System collects and removes waste gases
from the patient breathing circuit and the patient ventilation circuit. It can also collect any type of
gases or aerosolized medications that is intended only for the patient should not be breath by
others. AGSS systems to ensure the safety of your patients and staff.

4. Waste anesthetic gases (WAGs).
• Healthcare workers in a variety of settings( operating rooms, recovery
area, labour rooms, even radiology suites) can be exposed to the
anesthetic gases that are released or leak out during medical
procedures.
• Gases most commonly used include nitrous oxide, isoflurane,
desflurane, and sevoflurane.
• These gases and vapours are known as waste anesthetic gases
(WAGs).

5. Reasons for scavenging
• On the basis of epidemiological studies carried out since the mid 1960s, it has
been suggested that operating theatre staff and their wives and children are
subject to an increased risk of various pathologies, including  spontaneous
abortion, stillbirth, congenital abnormalities, low birth weight, altered sex ratio,
infertility, cancer, liver disease and kidney disease.
• Vessey and Nunn (1980) have critically reviewed both the epidemiological and
the animal studies, and conclude that, while the evidence for most of the above
hazards is unconvincing, the increased risk of abortion in female theatre staff is
reasonably well substantiated.
• Nitrous oxide inhibits the enzyme methionine synthase by inactivating its bound
co-factor methyl cobalamin (a form of vitamin B12), probably causing impairment
of deoxyribonucleic acid synthesis, which could well produce fetotoxic effects
(Shareet al., 1983).

6. Evidences of Adverse effects on Prolonged
Exposed.
• Nitrous Oxide: Several summaries of the epidemiologic studies of exposure
to N2O and reviews of the topic generally including animal and
retrospective studies (Purdham 1986; Kestenberg 1988; and NIOSH 1994)
have been published.
• They report a consistent excess of spontaneous abortion in exposed
women. Evidence for congenital abnormalities is less strongly associated
with exposure.
• Halogenated Hydrocarbons : Moreover, there is biological plausibility that
adds to the concern that high levels of unscavenged waste anesthetic
gases present a potential for adverse neurological effects or reproductive
risk to exposed workers or developmental anomalies in their offspring
(Cohen et al. 1980; Rowland et al. 1992).

7. Level of different agents which showed no
significant adverse effects on animal studies.
• 100 particles per million (ppm) for nitrous oxide
• 50 ppm for enflurane
• 50 ppm for isoflurane
• 10 ppm for halothane
• 20 ppm for sevoflurane (recommended by Abbot Laboratories)
• No limit set for desflurane although a 50 ppm target is advisable due to its
similarity to enflurane.
These levels were chosen because they are well below the levels at which
any significant adverse effects occurred in animals and represent levels at
which there is no evidence to suggest human health would be affected.

8. Recommended levels for different agents by
different agencies.
• In the United States, the maximum accepted concentrations of any
Halogenated agent should be less than 2 ppm.
• When such agents are used in combination with nitrous oxide, levels of
less than 0.5 ppm should be achieved.
• Nitrous oxide, (when used as the sole anaesthetic agent), at 8-hour time-
weighted average concentrations should be less than 25 ppm during the
administration of an anaesthetic.
• Holland has a limit of 25 ppm for nitrous oxide, whereas Italy, Sweden,
Norway and Denmark set 100 ppm as their limit for exposure to nitrous
oxide.
 It is not possible to set uniform levels without sufficient data.

9. In 2000, OSHA revised its recommendations on
waste anesthetic gases
In 2000, OSHA revised its recommendations on waste anesthetic gases in the light of current knowledge.
• The revised recommendations are published on the Internet for informational purposes only and are
regularly updated as information becomes available. The document is not published in the standard OSHA
manual on occupational hazards, however.
• The recommendations are advisory and have not been promulgated as a standard; rather, they are to be
seen as guidelines.
1. OSHA recommends scavenging of waste anesthetic gases in all anesthetizing locations and advocates work
practices to reduce trace levels of anesthetic gases in the ambient air.
2. A documented maintenance program should be in place for all anesthetic delivery machines, and an
ongoing education program for all personnel to inform them of these recommendations must exist.
3.OSHA recommends a program for monitoring trace anesthetic gases and also recommends a pre
employment medical examination for all employees.
4. Each institution also should have a mechanism in place for employees to report any work-related health
problems.

10. Association of Anaesthetists of Great Britain and
Ireland (1975) recommendation.
• As a result of the increasing concern about the possible hazards of
exposure to waste anaesthetic gases, the Association of Anaesthetists
of Great Britain and Ireland (1975) has recommended that all
anaesthetizing locations should be equipped with scavenging
systems, and this is now official DHSS policy (Department of Health
and Social Security, 1976).
• NIOSH recommendation to OSHA: Workers should not be exposed to
an eight hour time-weighted average of > 2 ppm halogenated agents
(not > 0.5 ppm if nitrous oxide is in use) or > 25 ppm nitrous oxide.

11. Target level for operating theatre pollution
In most jurisdictions, there is a legal requirement to scavenge waste gases to
maintain the level of waste gases in the Operating Room below the legally
acceptable limit.
 In the UK: the limits are typically  100ppm for nitrous oxide and 50ppm for
halogenated volatile anaesthetic agents (except halothane which is 10ppm).
In U.S.A NIOSH Recommendations published; 1977 by the (National Institute for
Occupational Safety and Health), states that:-
o Nitrous oxide maximum 25 ppm and
o Halogenated volatile gases maximum 2 ppm.
(Sharer and colleagues (1983) have criticized the NIOSH limit for nitrous oxide as
being too restrictive, and have suggested a limit of 200 p.p.m., based on a
consideration of the data on methionine synthase inactivation and fetotoxicity).

12. Anaesthetic Gases &
Agents in use.
Name of Agents Year of Introduction Present Use
Diethyl ether 1842 No
Nitrous oxide 1844 yes
Chloroform 1847 NO
Cyclopropane 1933 NO
Trichloroethylene 1934 No
Fluroxene 1954 NO
Halothane 1956 yes
Methoxyflurane 1960 Infrequently
Enflurane 1974 yes
Isoflurane 1980 yes
Desflurane 1992 yes
Sevoflurane 1995 yes
Nitrous Oxide and only few of the
anaesthetic agents are in use. Most
commonly used drugs are Sevoflurane,
Isoflurane , Desflurane & Halothane

13. Adverse effects
 National Institute for Occupational Safety and Health ,2007( NIOSH) states that “exposure to high
concentrations of waste anesthetic gases - even for a short time - may cause the following health
effects:
• Headache
• Irritability
• Fatigue
• Nausea
• Drowsiness
• Difficulties with judgment and coordination
• Liver and kidney disease”
These health effects were mainly noted for older anesthetics (e.g., trichloroethylene,
methoxyflurane) that are no longer commonly in use.
 Studies are inconclusive on the potential health effects from occupational exposure to some of
the newer anesthetics, such as isoflurane

14. NIOSH studies
• NIOSH (2007) continues: “Although some studies report no adverse health effects
from long-term exposure to low concentrations of waste anesthetic gases, several
studies have linked such exposure to miscarriages, genetic damage, and cancer
among operating-room workers.
• Studies have also reported miscarriages in the spouses of exposed workers and
birth defects in their offspring.”
• NIOSH (2015) later reports that “Some studies have documented adverse health
effects (e.g., headaches, fatigue, irritability, birth defects, miscarriages, liver and
kidney disease, cancer) from excessive exposure to anesthetic gas
 Scavenger systems were forced on anesthesia machines by the
‘recommendations’ of the National Institute for Occupational Safety and Health
(NIOSH).
The recommendations for room air concentrations of waste anesthetic gases is
25 ppm for nitrous oxide and 2 ppm for halogenated agents.

15. 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

16. Objective
 The objective of Anaesthetic gas scavenging systems(AGSS) to
prevent medical staff from inhaling the anaesthetic nitrous oxide and
halogenated hydrocarbons administered to patients during surgery.
In most jurisdictions, there is a legal requirement to scavenge waste
gases to maintain the level of waste gases in the Operating Room
below the legally acceptable limit.
In addition to the legal requirement there is an Occupational Health
requirement to maintain a safe workplace and limit exposure to
potentially harmful gases and agents.

17. Guidelines for controlling pollution in OR
• There is no association between occupational exposure to
anaesthetic agents trace levels and adverse health effects.
• There are no agreed international standards of the maximum
accepted concentrations of agents in the theatre environment.
• Routine monitoring and testing (PPM) are mandatory.

18. Factors responsible for theatre pollution
Anaesthesia Techniques Anaesthesia Machines
• Leaks from various connections
like tubing connections if not
fitting properly, soda lime
canister etc.
• Others: Cryosurgery Unit,
Cardiopulmonary bypass circuit
if vapor is used.
Poorly fitting facemask
Pediatric breathing system( T-piece)
Un-cuffed tracheal Tubes
Gases coming out through APL valve
Gases coming through ventilator exhaust
Exhalation gases during recovery
Spillage during filling of vaporizers

19. How to reduce pollution in OR?
 1. Adequate theatre ventilation and air conditioning, with frequent and rapid changing of the circulating air (15–20 times per hour).
 Theatres that are unventilated are four times as contaminated with anaesthetic gases and vapours compared to those with proper
ventilation.
 A non-recirculating ventilation system is usually used. A recirculating ventilation system is not recommended. In labour wards, where
anaesthetic agents including Entonox are used, rooms should be well ventilated with a minimum of five air changes per hour.
 2. Use of the circle breathing system.
 This system recycles the exhaled anaesthetic vapours, absorbing CO2.
 It requires a very low fresh gas flow, so reducing the amount of inhalational agents used.
 3. Total intravenous anaesthesia.
 4. Regional anaesthesia.
 5. Avoiding spillage and using fume cupboards during vaporizer filling.. Modern vaporizers use special agent-specific filling devices as a
safety feature and to reduce spillage and pollution.
 Good technique will also help lessen exposure.
 6. Scavenging of Anaesthetic gases.

20. Good technique will also help lessen
exposure.
• Good mask fit
• Avoid unscavengeable techniques if possible (insufflation)
• Prevent flow from breathing system into room air (only turn on agent and nitrous
oxide after mask is on face, turn them off before suctioning)
• Washout anesthetics (into the breathing circuit) at the end of the anesthetic
• Don’t spill liquid agent
• Use low flows
• Use cuffed tracheal tubes when possible
• Check the machine regularly for leaks
• Disconnect nitrous oxide pipeline connection at wall at the day’s end (beginning?)
• Total intravenous anesthesia

21. Scavenging of waste Gases
• In any location in which inhalation anaesthetics are administered,
there should be an adequate and reliable system for scavenging the
waste anaesthetic gases.
• A scavenging system need to be capable of collecting the waste
anaesthetic gases from the breathing system and disposing them
safely.
Unscavenged operating theatres can show a very high levels of N2O.
(400–3000 ppm).
Scavenging of waste gases may be a passive or active system.

22. A passive scavenging system.
• A passive scavenging system operates without the use of suction,
since the positive pressure of gas in the breathing circuit pushes
waste anesthetic gases into the scavenging system.
• One-way valves in the interface help to move waste anesthetic gases
outdoors or into a non-recirculating air ventilation system.
• A passive scavenging system does not involve the use of a vacuum
pump or suction.

23. Active scavenging systems
• Active scavenging systems use suction, or a vacuum pump, to actively
remove waste anesthetic gases from the breathing circuit and draw
these gases into a scavenging system.
• The interface of an active system requires a negative pressure relief
valve in order to prevent negative pressure from reaching the
breathing circuit and affecting the patient’s lungs.

24. Comparison of both the systems
 Active System
• Uses a device like suction to draw
gases from breathing system.
• Mostly uses a compressor to draw
the gases and agents.
• Expensive
• Requires maintenance.
• Requires a means to protect the
patient's airway from the
application of suction, or buildup of
positive pressure.
Passive System
• This system uses no suction, pressure
in the gas line helps to drive out the
gases out of the machine.
• It must be located adjacent to an
outside place, the pipe simply passes
through a whole in the wall.
• It is inexpensive
• Dose not require maintenance.
• Requires the patient to be protected
from a positive pressure buildup only
if there is obstruction in the exit limb.

25. The basic functional components of an Anaesthetic Gas
Scavenging System are as follows:
• 1.A collecting assembly / shroud with a relief valve by which the
waste gas leaves the breathing or ventilation circuit.
• 2.A transfer system of tubing to conduct waste gases to the
Scavenging Interface.
• 3.The Scavenging Interface, and
• 4.A Disposal line to conduct the waste gas to a passive evacuation
system, or a Waste Anaesthetic Gas Disposal/Medical Vacuum system
via a station outlet.

26. Schematic diagram showing the
different components of scavenging
system
1.A collecting assembly / shroud with a relief valve by which the
waste gas leaves the breathing or ventilation circuit.
2.A transfer system of tubing to conduct waste gases to the
Scavenging Interface.
3.The Scavenging Interface, and
4.A Disposal line to conduct the waste gas to a passive evacuation
system,

27. A collecting Assembly( Receiving system)
Gas collection assembly, (tubes connected to APL and vent relief valve)
 A reservoir bag can be used receiving or collecting system .
 Two spring-loaded valves in the system guard against excessive positive
(1000 Pa) in case of a distal obstruction or negative (–50 Pa) pressures in
case of increased demand in the scavenging system.
Without these valves, excessive positive pressure increases the risk of
barotrauma, should there be an obstruction beyond the receiving system.
Excessive negative pressure could lead to the collapse of the reservoir bag
of the breathing system and the risk of rebreathing.

28. Collecting System

29. Transfer System
It is a simple wide bore pipe without any leak which
can transfer from the collecting system to Scavenging
interface. Can be copper pipe.
Transfer tubing (19 or 30 mm, sometimes yellow color-
coded)
The transfer hose should always be fitted with a
pressure relief valve (10cmH2O) such that if the
transfer hose were to become occluded for any reason
the patient would still have an expiratory path.

30. Scavenging Interface
• The scavenger interface is the most important component.
• The extraction flow rate ensures that waste anaesthetic gases are adequately removed from the
system. It protects the breathing circuit from excess positive or negative pressure.
• Positive-pressure relief valve is mandatory to vent excess gas in case of occlusion distal to a
closed interface. If active disposal system in use, must have negative pressure relief valve as well.
• Reservoir highly desirable with active systems.
• The induced flow rate should be as low as possible with the system ideally being passive between
the patient and the receiving unit and active from the receiving unit to the exhaust point.
• The importance of this flow rate is that if it falls too low it may not be sufficient for waste gas
removal.
• If too high, this would lead to the waste gases spilling out from the base of the receiving reservoir
unit into the immediate working environment; it may lead to an increase of the induced flow at
the patient connection port.

31. Closed interface
Closed interface communicates with
atmosphere only through valves.
Should adjust vacuum pressor so that
reservoir bag neither flattened not over-
distended.

32. Active Scavenging Interface closed
system.
The Ohio scavenging interface has
connections for the outlets from the
breathing system and ventilator (A),
one or two reservoir bags (B), and
the vacuum line (V).
The suction is controlled by the
needle valve (N).
There are both positive (P1) and
negative (P2) pressure relief valves
in case the reservoir bag becomes
empty or too full.

33. Function of the Positive and Negative Pressure
Relief Valves
The scavenging system has negative and positive pressure relief valves to
prevent excessively high or low pressures from developing in the
scavenging manifold and being transmitted to the patient via the breathing
circuit.
The positive pressure relief valve: will lift up and open at approximately 5 cm
H2O. This happens when the vacuum is too weak or if the vacuum adjustment valve is
completely closed.
A slight hissing or rattling sound can be heard (indicating the venting of exhaust gases
into the room) during the expiratory phase of mechanical ventilation or when the manual
bag is squeezed. In addition, the scavenging bag will be fully inflated.
Negative pressure relief valve: to prevent negative pressure from being
transmitted to the breathing circuit, will actuate at approximately -0.25 cm H2O and
allow room air to enter the scavenging system to "break" the vacuum. The scavenging
bag will be collapsed flat.

34. Open interface
Open interface has no valves, and is open to
atmosphere (allows both negative and
positive pressure relief).
Should be used only with active systems.
Remember that slight hissing from an open
interface is normal- there is no audible
indication of waste gas leaks.
Safer for the patient (no hazard of positive or
negative pressure being applied to the
airway as a result of scavenger failure).
The risk of occupational exposure for
providers ignorant of their proper use is
higher with the open interface (Anesth
Analg 1992;75:1073).

35. Home made Simple
active scavenging
interface
A cylindrical plastic jar.
Suction through valve attached at the
bottom.
At the top there are two inlets, one for waste
gas pipe insertion the other one for air to
enter if creates excessive negative pressure.

36. The disposal system
 The disposal system is a wide-bore copper pipe leading to the
atmosphere directly or via the theatre ventilation system.
Gas disposal assembly (active or passive, active system most
common uses the hospital suction system)

37. Passive disposal system
• In the past, the standard of collecting waste gases has been through
passive methods, which include (depending on the flow rate of the
delivery gas) pushing the waste gas into an activated charcoal
canister.

38. Activated charcoal cartridges.
• Activated charcoal cartridges can also be used for passive
scavenging.
• It is important to note the limitations of these cartridges: they are
less effective at high anesthesia flow rates, they must be changed
every 12 hours, and care must be taken to avoid occluding the
cartridge’s air exit holes.
• When used correctly, however, activated charcoal cartridges can
effectively decrease waste anesthetic gas exposure.

39. F/air Canister
A sensible answer to anesthesia gas
problems in the operating room, the F/AIR
anesthesia gas filter was specifically designed
to remove waste anesthesia gases such as
ISOFLURANE, HALOTHANE, ENFLURANE,
SEVOFLURANE, etc. from the operating room
environment.
Economical to use, with an average useful life
of 12 to 15 hours, the F/AIR is easily
adaptable to anesthesia machines.
The F/AIR can remove no less than 50 grams
of pure halogenated anesthetic gases and
can then be conveniently discarded.
The F-Air® canister must be changed after 8
hrs of normal use or a weight gain of 50
grams.
Disposable
Ready to use

40. WAG Activated Charcoal
Canisters
Activated Charcoal Filtration System
Contains 2 pounds of the highest quality
activated charcoal available to make the WAG
the most effective filter on the market.
Will adsorb a minimum of 200 grams
Halogenated Agent. (4 times the amount of F-
Air Canisters).
Unique design traps Isoflurane/Sevoflurane
Agent molecules in the canister.
Relief holes on top ensure that the canister can
sit upright on a flat surface.
Universal tubing connections: 19mm (standard
in industry), 22mm, and fitting for 15mm male
to use ¼” ID Tubing.
Passed independent testing according to OSHA
regulations of 2ppm.
No breakthrough exhibited at +/- 60 LPM flow
rate (Verified via infra red spectrophotometer).

41. Drawing showing the
flow system of gases.

42. Diagram of a passive scavenging system.
Modern scavenging system has four components.
a). Collecting System:
b).Transferring System:.
c). Receiving System:
d). Gas disposal Assembly: May be a passive or active
disposal unit.

43. Passive System
The passive system is simple to construct with zero running cost.
Components are :-
1. The collecting and transfer system which consists of a shroud connected to
the adjustable pressure limiting (APL) valve (or expiratory valve of the
ventilator).
2. A 30-mm connector attached to transfer tubing leads to a receiving system.
3. Receiving System.
4. Gas Disposal Unit or assembly.
The 30-mm wide-bore connector is designed as a safety measure in order to
prevent accidental misconnection to other ports of the breathing system .

44. Draw backs of passive scavenging system
• Scavenging systems are either passive or active.
• Passive systems have a large tube or canister with an inlet, an outlet,
and one open end.
• The waste anesthetic gases from the ventilator and ‘pop-off’ valve
enter the inlet.
• Suction is applied at the outlet.
• If the suction rate exceeds the rate of entry of anesthetic gases, room
air is drawn into the open end.
• If entry of anesthetic gases exceeds the rate of suction, excess gases
exit via the open end into the room.

45. Active system
• The purpose of the system from the plant to the terminal outlet is to provide the extraction flow
rates to remove waste anaesthetic gases from the receiving unit reservoir.
• The role of the receiving unit is to provide a safe interface between the patient and the extraction
flow rates.
Components
• The collecting and transfer system is similar to that of the passive
system .
• A fan or Vacuum unit to establish flow.

46. Adverse effects of active system.
• Active systems contain negative and positive relief valves to release excess
pressures.
• Active systems have been associated with higher exposure of gases in the
environment than passive systems.
• When the reservoir bag overinflates due to an excess inflow of anesthetic gases,
pressure increases until the positive pressure relief valve opens to vent excessive
gases into the room.
• A valve malfunction will allow the pressure increase in the patient circuit to
increase to the limit of the elastic properties of the particular reservoir bag.
• High pressures can be detected in the patient circuit by the circuit pressure gauge
and/or by the high pressure gauge of the ventilator.
• If high pressure persists the patient may develop decreased cardiac output
secondary to high intrathoracic pressure, and/or pneumothorax.

47. Adverse effects of active system(Conti-)
• When the suction rate exceeds the anesthetic gas inflow rate, the
reservoir bag deflates.
• Usually any excessive negative pressure is offset by room air entering
the negative pressure relief valve.
• Some scavenger systems have a second or backup relief valve.
• The pressure gauge of the ventilator may detect an excessive negative
pressure state.
• If the negative pressure relief valve system malfunctions, it could be
possible for the suction to remove anesthetic gases from the patient
circuit.

48. Mechanism of action
• 1. The exhaled gases are driven by either the patient’s respiratory efforts or the
ventilator.
• 2. The receiving system should be mounted on the anaesthetic machine to minimize the
length of transfer tubing, therefore minimizing resistance to flow.
• Problems in practice and safety features
• 1. Connecting the scavenging system to the exit grille of the theatre ventilation is
possible. Recirculation or reversing of the flow is a problem in this situation.
• 2. Excess positive or negative pressures caused by the wind at the outlet might affect the
performance and even reverse the flow.
• 3. The outlet should be fitted with a wire mesh to protect against insects.
• 4. Compressing or occluding the passive hose may lead to the escape of gases/vapours
into the operating theatre and thereby polluting it.
• The disposal hose should be made of non-compressible materials and not placed on the
floor.

49. Requirements of standard Scavenging System
The draft BS( British Standard) on scavenging equipment includes the
following provisions for patient safety:
(1) At a continuous flow of air 30 litre min"1, the scavenging system
should not impose a greater resistance than 50 Pa.
(2) In the event of total obstruction of the system, or failure of the
power supply, the resistance should not be greater than 1 kPa at a
flow of 30 litremin"1. If the transfer tubing is less than 1 m in length,
the necessary pressure relief may be afforded by the receiving
system.
(3) The scavenging system shall not create a sub-atmospheric
pressure in the collecting system of more than 50 Pa.

50. Monitoring the functioning of Scavenging system.
 Sampling procedures for evaluating waste anaesthetic vapour concentrations
in air should be conducted for nitrous oxide and halogenated agents on a yearly
basis in the UK and on a quarterly basis in the USA in each location where
anaesthesia is administered.
 Monitoring should include:
• Leak testing of equipment
• Sampling air in the theatre personnel breathing zone.
Planned preventative maintenance (PPM) programme. Anaesthetic equipment,
gas scavenging, gas supply, flowmeters and ventilation systems must be subject
to a maintenance programme.
, The general ventilation system and the scavenging equipment should be
examined and tested by a responsible person, at least once annually .

51. WHAT IS AN IDEAL SCAVENGING SYSTEM?
.
1.Should not affect the ventilation and oxygenation of the patient.
2.Should not affect the dynamics of the breathing system.
3.A well-designed scavenging system should consist of
i. a collecting device for gases from the breathing system or ventilator at the site of
overflow,
ii. a system to carry waste anaesthetic gases from the collecting device and a method for
limiting both positive and negative pressure variations in the breathing system.
4.The performance of the scavenging system should be part of the
anaesthetic machine check.
5.Scavenging systems can be of a passive or active type.

52. WHAT IS AN IDEAL SCAVENGING SYSTEM (CONT-)?
6.The scavenger system must be independent of the main hospital
ventilation system.
7. The scavenging system should be kept in good repair to prevent
leaks using a maintenance and inspection program as listed below.
8.Gases are not discharged near the air intake of the building or
surrounding buildings.
9. In the event of a “Code RED”, hospital ventilation is shut down to
reduce the potential spread of a fire but the scavenger system must
continue to work.
Consider using a WAG collection canister that can be attached to an
anesthetic gas machine before the scavenger. It will capture the
agents (except for nitrous oxide).This technology reduces emissions to
the atmosphere by capturing the agents and recycling them.

53. An effective waste anesthetic gas management program
includes:
• Engineering Controls,
• Work Practices,
• Air Monitoring and,
• Hazard Communication and Training.

54. Air Monitoring
• One of the tools used to measure exposure to waste anesthetic gases is air
monitoring.
• Monitoring may be continuous or periodic but should adequately measure
exposure in the work areas and surrounding areas.
• Monitoring can aid in identifying the presence and location of leaked gases
and the effectiveness of corrective measures.
• As most halogenated anesthetic gases cannot be detected by smell (unless
they are in high concentration) proper monitoring becomes all the more
critical.
• Nitrous oxide is an odourless and colourless gas and can only be detected
by WAG monitor.

55. Hazard Communication and Training
• Employers should develop and implement a written hazard communication program regarding WAGs
that includes description of the physical and health hazards of anesthetic agents in use, the compiling
and availability of up to date material safety data sheets on all anesthetic gases used; proper labelling
of canisters, tanks, and containers; and a comprehensive employee training and information program.
• The training program should list steps, the workers can take to protect themselves from the hazards of
WAGs.
• The program should include information on steps taken by the employer;
- such as engineering controls,
- clearly outline emergency procedures to contain spills,
- describe safe work practices and the use of any personal protective equipment, and
- detail the use of continuous monitoring devices.
• The training program should clearly outline all methods and observable indicators that can detect the
presence and release of anesthetic gases.
• Spills should be treated as emergencies. Spills of anesthetic agents must only be cleaned up and
controlled by properly trained and equipped personnel

56. Good technique that lessens expose to waste
anaesthetic gases.
• Good mask fit
• Avoid unscavengeable techniques if possible (insufflation)
• Prevent flow from breathing system into room air (only turn on agent and nitrous
oxide after mask is on face, turn them off before suctioning)
• Washout anesthetics (into the breathing circuit) at the end of the anesthetic
• Don’t spill liquid agent
• Use low flows
• Use cuffed tracheal tubes when possible
• Check the machine regularly for leaks
• Disconnect nitrous oxide pipeline connection at wall at the day’s end (beginning?)
• Total intravenous anesthesia

57. Certain devices & systems for an ideal
scavenging system.

59. Passive Outlet for
AGSS

60. Separate Suction System for Anaesthesia gas scavenging

61. Exhaust Fan Use to
Scavenge AGSS

62. Lack Circuit(J. A. LACK)

63. Connection to be fitted to APL valve

64. Devices using N2O

65. Thanks.