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

Are we dumping waste in OR ?

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

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

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

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).

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.

What does scavenging do?  Unscavenged operating rooms show  ppm halothane, and 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 and 1 ppm

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 )

Components

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

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

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

Interface open or closed

Open interface

Closed interface

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.

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

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.

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.

Passive  Piping Direct to Atmosphere

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

Passive  Catalytic decomposition  can be used to convert nitrous oxide to nitrogen and oxygen

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

Active – venturi principle

Simple scavenging system

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

Other sources  Extracorporeal Pump Oxygenators  Gas monitors  Cryosurgical units

Check scavenging systems Beware they can malfunction

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

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

Even if u cant understand like this- thank you all