Scavenging

1. Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics PhD(physiology) Mahatma gandhi medical college and research institute, puducherry, India Scavenging

2. Are we dumping waste in OR ?

3. What is it ? • Scavenging is the collection and removal of vented anaesthetic gases from the OR. • the amount of anesthetic gas supplied usually far exceeds the amount necessary for the patient. • If a FGF -sized volume enters the breathing circuit each minute, the same flow must leave it • OR pollution is decreased by scavenging

4. Concerns • Reduced fertility levels in females • Increased risk of spontaneous abortion • Congenital abnormalities in children • Increased risk of cancer for females • Adverse effects on liver and kidneys • Reduced audiovisual response • The evidence that trace anesthetic gases are harmful is at present suggestive rather than conclusive

5. What is just OK ?? • 100 particles per million (ppm) for nitrous oxide 50 ppm for enflurane 50 ppm for isoflurane 10 ppm for halothane • . Trace gas levels higher • paediatric anesthesia, in dental in poorly ventilated recovery rooms

6. What is ppm ?? • Trace gas levels are usually expressed in parts per million (ppm), • which is volume/volume (100% of a gas is 1,000,000 ppm; 1% is 10,000 ppm).

7. What is in USA ?? • National Institute for Occupational Safety and Health (NIOSH) recommends that exposure of operating room workers to halogenated agents • should be kept below 2 ppm. N2O • guide should result in levels of approximately 0.5 ppm of the halogenated agents.

8. What does scavenging do? • Unscavenged operating rooms show • 10-70 ppm halothane, and 400-3000 ppm N2O. • Minimal scavenging brings these levels down to 1 and 60 ppm respectively • careful attention to leaks and technique can yield levels as low as 0.005 and 1 ppm

9. Components of the scavenger system • Gas collection assembly, (tubes connected to APL and vent relief valve) • Transfer tubing (19 or 30 mm, sometimes yellow color-coded) • Scavenging interface • Gas disposal tubing (carries gas from interface to disposal assembly) • Gas disposal assembly (active or passive - active most common, uses the hospital suction system)

10. Components

11. Collection collects excess gases and delivers them to the transfer means. It may attach to, or be an integral part of a source 30 mm No leaks APL valves , ventilator ports – systems available

12. Transfer tubing • conveys gas from the collecting assembly to the interface • as short and wide • Easily connectable and dis connectable • resistant to kinking. • It should not touch the floor

13. Interface • serves to prevent pressure increases or decreases in the scavenging system from being transmitted to the breathing system • positive pressure relief, • negative pressure relief, and reservoir capacity

14. Interface open or closed

15. Open interface

16. Closed interface

17. Inbuilt scavenging systems • Open interfaces are found on most newer gas machines (e.g. Fabius GS, Narkomed 6000, ADU). • Aestiva may have an open or closed interface.

18. Disposal assembly • Active – negative pressure inside the system • Passive – positive pressure • waste gases proceed passively down corrugated tubing through the room ventilation exhaust grill of the OR

19. Active • Active systems are usually more effective • allow small-bore tubing to be used, • less resistance. • aid room air exchange. • Expensive • not automatic and must be turned ON and OFF. • Their use requires that the interface have negative pressure relief.

20. Passive • Simpler • may not be as effective in lowering trace gas levels, because the positive pressure encourages outward leaks. • less expensive to operate than active systems.

21. Passive • Piping Direct to Atmosphere

22. Passive • Adsorption Device • A canister containing activated charcoal is connected to the outlet of the breathing system and removes halogenated anaesthetics by filtration

23. Passive • Catalytic decomposition • can be used to convert nitrous oxide to nitrogen and oxygen

24. Active • connect the exhaust of the breathing system to the hospital vacuum system via an interface controlled by a needle valve.

25. Active – venturi principle

26. Simple scavenging system

27. Active • Vacuum • Two or single • May malfunction • Excess neg. pressure • The outlet to atmosphere should be away from windows and ventilation intakes

28. Other sources • Extracorporeal Pump Oxygenators • Gas monitors • Cryosurgical units

29. Check scavenging systems Beware they can malfunction

30. Alterations in Work Practices • Checking Equipment Before Use • Proper Mask Fit • Preventing Anesthetic Gas Flow Directly into the Room • Washout of anaesthetic gases at the end of a case • Preventing Liquid Agent Spills • Proper Use of Airway Devices

31. Alterations in Work Practices • Use cuffed tracheal tubes when possible • Check the machine regularly for leaks & Leak Control • Using Low Fresh Gas Flows • Using Intravenous Agents and Regional Anaesthesia

32. Even if u cant understand like this- thank you all