MCW Anesthesiology Intranet
MCW Anesthesiology Intranet

Update 3/20: Anesthesia Machine Circuits, Transport Vents, Ambu Bags, Intubations

I wanted to update everyone on some changes.  As you know this is a dynamic situation and information changes daily as we learn more.

Anesthesia Machine Circuits

On Monday we added viral filters as a precautionary measure until our questions were answered by outside professionals.  One of the questions was how many microns is COVID – 19 and how many microns does our standard HME filter?  The standard HME WILL filter COVID-19.  Moving forward our basic circuit set-up is acceptable to use and we no longer have to worry about the protection of our machines concerning filtration.

The machine also has an internal viral filter which protects the machine from the sample line. This was a concern for MAC cases.

Any condensation or moisture in the water trap is also not a concern.  The machine has a constant flow of 250cc to prevent any possible backflow.  If the water trap retains too much condensation it should be replaced as usual (we also change the water trap each month).

Transport Vents

There should be 2 viral filters on the transport vent circuit.  One at the expiratory end and one at the Y.  The machine should be turned off before disconnecting the patient.  In addition, clamping the circuit or using the blue cap at the Y are also extra precautionary methods.

Ambu Bags

We are now adding Bacterial/viral filters to each ambu bag and they will also be located in the airway boxes.


Please communicate with the anesthesia techs if they need to be present for intubations.  They can be on standby outside of the room or also be present in the room wearing an N95.


If you have any questions or need further clarification please let me know.


Thank you,


Lyndee Anzalone

Anesthesia Manager

Phone: 414-805-3706 | Pager: 414-314-0872


Froedtert & the Medical College of Wisconsin

9200 W Wisconsin Avenue
Milwaukee, WI 53226