Let's start with a typical desflurane-based general anesthetic at 1 MAC and relatively high gas flows, which would be typical upon induction.  Here is the calculator input below:

In one hour of running this anesthetic, the carbon dioxide equivalent is nearly 1,700 miles, the distance of a 24 hour drive from Barcelona, Spain, through France, Italy, Germany and Switzerland, to Prague, Czech Republic!  

Let's use this as a benchmark and see if there are any ways we can reduce cost and carbon dioxide impact.

In our next example, let's look at the effect of simply decreasing gas flows.  

Notice the 82% decrease in carbon dioxide emissions and cost!  Here we see that decreasing gas flows is a simple strategy to conserve the amount of volatile anesthetic used.

Now let's try swapping out desflurane for the MAC equivalent of sevoflurane.  

Notice the 98% reduction in carbon dioxide produced!  Of all the volatile anesthetics, desflurane by far has the largest emissions impact.  Try the other volatile anesthetics as well.  You will find that the others will have an even lower amount of carbon dioxide produced.

Also, because prices vary, you can input your own prices of inhaled anesthetics to calculate the cost difference.  The link is on the calculator and can be found here:

https://jscalc.io/calc/do45BOJVrzXMaEGC

Where does nitrous oxide fit in all of this?  Let's try a typical strategy of applying high flows of nitrous oxide to speed emergence.

Here you can see that nitrous oxide has a huge amount of carbon dioxide emissions!  In one hour of running 10L/min of nitrous oxide, you have a driving equivalent of 1,334 kilometers.  That is farther than driving from Paris, France to Madrid, Spain, a trip that takes well over 12 hours!

Nitrous oxide is one of the most harmful greenhouse gases, and decreasing the amount of nitrous significantly cuts your carbon emissions.

Another option for general anesthesia is TIVA.  Let's take a look at a typical TIVA anesthetic using propofol and remifentanyl in a 70kg patient.

Compared to our benchmark of desflurane + high gas flows, a TIVA based anesthetic is nearly 10,000 times less!
 This is a massive decrease in carbon emissions and cost.  Once again, the costs are approximate, so feel free to enter your own costs in our custom cost calculator.

https://jscalc.io/calc/do45BOJVrzXMaEGC

Another option you can test in our calculator is a regional anesthetic.  Note that the calculator will only incorporate the cost and carbon dioxide impact of the drugs used.  The regional needles, kits, etc. are beyond the scope of this project.  

Let's try a single shot nerve block with bupivacaine followed by sedation with propofol in a 70kg patient.

Once again, notice a decrease in carbon dioxide impact on the same order as TIVA!  Using other intravenous anesthetics and local anesthetics will yield similar results, but feel free to play around with the drugs we have included.

We hope that this brief tutorial has illustrated the carbon dioxide impact and approximate cost of various anesthetics.  Enjoy playing with the calculator, and feel free to leave comments and suggestions below!