Scavenging of waste anaesthetic gases.

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. W aste 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 N 2 O 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. I n 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:- Nitrous oxide  maximum 25 ppm and 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   T here 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 CO 2 . 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 N 2 O. (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 (10cmH 2 O) 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 : t o 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 ). T he 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. , T he 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.

58. Passive Outlet for AGSS

59. Separate Suction System for Anaesthesia gas scavenging

60. Exhaust Fan Use to Scavenge AGSS

61. Lack Circuit(J. A. LACK)

62. Connection to be fitted to APL valve

63. Devices using N 2 O

64. Thanks.