To give readers an idea of these newer technologies, I will speak to the advancements by Drager and GE. Here’s what I’m talking about:

1. Drager anesthesia machines have the “Low Flow Wizard” technology combined with piston driven “bellows”. The Low-Flow Wizard display shows you the “Required FG Flow” and “Total Flow” (what your flows are). Any flow rates greater than requirement are indicated as “Efficient” which is Drager’s word for “Sufficient”. Since the system continuously displays required fresh gas (FG) flow, the provider can see in real time whether their delivered fresh gas flows are at or above what is required for ventilation. As shown in the example (photo), fresh gas flows as low as 0.3 – 0.4 L/M will typically be sufficient for “efficient” ventilation. As usual, keep an eye on the FiO2 and adjust if needed.

How is this physically possible?

• These machines are built “tight” to have minimal to no leak.
• The gas analyzer flow is returned to the circuit.
• The software considers all losses and additions of flow: These algorithms assess fresh gas entering the breathing system, oxygen and volatile agent uptake by the patient, CO2 production by the patient, leakage into the environment, CO2 absorption by the absorbent, and waste gas into the WAGD. By adding up all of the “losses” it is possible to calculate a required amount of FG flow.

2. GE anesthesia machines have the End-tidal Control software system that allows providers to set targets for end-tidal volatile agents. The system automatically adjusts the fresh gas flows breath-by-breath such that once the target is attained, flows decrease substantially (below 1 L/M) during anesthesia maintenance.

What does this all mean? . . . providers can routinely deliver what is akin to closed circuit anesthesia, and minimize the amount of volatile agent released to our atmosphere. If we can safely reduce the release of volatile agent greenhouse gases by 75% (0.5 L/M fresh gas flow) without compromising patient care, why not do it. Sure, a 50% reduction (1 L/M) is a step in the right direction, but it is still more than double of what we can do with minimum safe flow inhalational anesthesia at 0.4 – 0.5 L/M. Add to this the significant additional benefit of substantial monetary savings from more efficient usage of volatile agents (less waste) which has immediate results for healthcare institutions. So, if or when you upgrade to new anesthesia machines with these technologies, chip down fresh gas flows at your level of comfort . . . . 0.8 . . . 0.7 . . . . . . . 0.5 L/M. For additional piece of mind, you may want to increase your FiO2 setting to 70-100% if you are concerned about having lower FiO2 levels (30’s %) due to the low flow settings.