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I N H A L A T I O N
A G E N T S
LOWER LIMIT
When Does Flow Become Low?
the market will ensure you're paying the highest price possible.
Low flow is a way to get gas costs
below $6 an hour.
• Environmental benefits. Any
DANGER ZONE Delivering less than 500ml of
anesthetic gas per minute demands careful
patient monitoring.
time you use less nitrous oxide
and anesthetic gases, you release
less greenhouse gas. Sure, it's a
very small amount to keep out of
the atmosphere, but (a) it's the
responsible thing to do and (b) if
L
ow-flow anesthesia is anything less than
500ml of anesthetic per minute traveling
through the gas circuit. Minimal flow —
generally considered the sweet spot — is just
you want to market your facility
above 500ml per minute. But you can go even
as "green," using low flow when
lower, below 500ml per minute, which requires
appropriate helps you be truthful
very accurate monitoring of the gas analyzer,
about that selling point.
pulse oximeter and capnograph.
• Faster recoveries. This is the
Below 500ml per minute, the anesthesia
biggest factor: Low-flow anesthe-
provider has to be extremely vigilant in watching
sia keeps your patients warm.
for changes. The gas analyzer itself removes
The higher the gas flow rate, the
about 200ml from the gas circuit every minute —
more body heat is lost. This is
so if you're putting only 500ml into the patient,
because dry inhalational gases
you're losing 40% of it. You have the option of
need to be humidified, and the
taking the exhaust gas from the analyzer and
water vapor that's used takes
feeding it back into the circuit for a little extra,
body heat with it as it's exhaled.
but most providers (myself included) just vent
Low-flow anesthesia preserves
the exhaust gas. Above 500ml per minute, so
the body's heat, making it espe-
long as everything goes as planned, you can
cially useful in longer procedures,
achieve low flow without the same continuous
in which normothermia is a major
scrutiny of monitors and patient status.
challenge and objective.
— Clifford Gevirtz, MD, MPH
Low-flow anesthesia is appropri-
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O U T PAT I E N T S U R G E R Y M A G A Z I N E | J U LY 2013
