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I N H A L A T I O N A L
A N E S T H E S I A
GRADUAL DROP
How Low Can You Go?
M
ost anesthesia providers use 2L to 5L of fresh gas flow per
minute. Why aren't more dialing back during the maintenance phase of anesthesia when lower fresh gas flow is
needed to meet a patient's demand for oxygen and anesthetic? In my
estimation, less than 10% of providers are using low-flow techniques
because it's not yet ingrained in the culture of anesthesia.
The accepted parameters of low-flow have changed over the years,
dropping gradually from 2L per minute to 1L per minute in the late
1990s, due in large part to the increased awareness of the greenhouse
effect anesthetic gases have on the atmosphere. Now, if you have a
closed breathing circuit with a good absorber or even an LMA — you
can deliver low-flow anesthesia without an endotracheal tube — with
an excellent seal, you can drop down to 300cc (0.3L) per minute,
although many pro-viders consider 500cc (0.5L) per minute to be an
adequate (and safe) low-flow rate.
The low threshold is partially based on the patient's oxygen requirement, as individuals of average size and weight need no more than
300cc of oxygen per minute to survive.
— Ashish C. Sinha, MD, PhD
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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 O N L I N E | F E B R U A R Y 2013
