Transcript Scavenging - Anesthesia Slides, Presentations and Publications by

SCAVENGING
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
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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
 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
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
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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
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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
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