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fresh gas flowing or requested per second. The software can then divert or limit
the excess fresh gas — or limit the ventilator breath — to give the patient only
what the provider requested. For example, if you want to give 500 ml of gas per
breath, but the computer sees that there's an additional 68 ml coming from the
fresh gas flow, it will recalculate and only give the patient the needed 432 ml
from the ventilator. Alternatively, it could redirect that 68 ml or shut it off during
inspiration.
Most modern machines also have compliance compensation as part of the
breathing circuit. When the machine pumps gas into the patient, some of it is lost
in the stretchable breathing tube. This is called compliance. Usually about 2 to 3
ml/cm is lost, so if your desired volume is set to 500 ml, you could lose between
40 and 60 ml in each breath.
New machines fight this by automatically checking for compliance in the cir-
cuit and then compensat-
ing for that. So if you want
a 500 ml volume, and the
machine detects 60 ml are
lost due to compliance, the
ventilator will instead give
the patient 560 ml.
Updated breathing cir-
cuits are smaller and more
compact, plus many can
detect, report and even
compensate for leaks.
Another new feature is the
warming of the breathing
circuit itself, which helps
avoid moisture in the
machine due to the
