Aerosol Dilution Fan

As you know, aerosol generating procedures (i.e. intubation and extubation) are a high risk to the anaesthesia team. While critical care aspects of  COVID capture the headlines, patients also come for urgent / emergency surgery as well. These patients, even when asymptomatic, may pose a risk and I was wondering about how we can reduce aerosol risk.

I know that there are “intubation boxes” that people are trying. But in my opinion, extubation is probably even more dangerous than intubation, because the patient no longer has muscle relaxants and therefore may cough and / or need brief bag mask ventilation.

A key safety factor in the operating room is the theatre air exchanges that dilute and take away aerosol.

However, one would expect that the aerosol density would be highest around the patients mouth, making this area of particular risk to the anaesthetic team. It is possible that the general airflow in the operating room may not be quick enough to reduce this local high density area of aerosol.

The idea presented here is that perhaps a simple well placed fan may push away and dilute the local concentration of aerosol from the area the anaesthetic team is placed. The theatre ventilation system then can eliminate the pushed away aerosol.

Before we discuss this further,  I must warn you that this is only an idea. I do not know if it is effective or safe to do it. If you decide to try it, it will be at your own risk. I am no expert in airflow, virology and other complex stuff.


So how might a cheap pedestal fan help us ?

 


Let us begin by the patient, who could potentially be having COVID, being  on the operating table, waiting to be intubated for surgery. The viruses are of coming at a high density from the patients mouth.


Now let us introduce the pedestal fan to the scene. The fan is OFF at the moment. It is placed as shown, reasonably close enough to blow a strong flow of air. The fan needs to be tall enough to be roughly level with the faces of the anaesthesia team.


The area opposite the fan should have no one as when the fan is switched on, the fan will blow across the face of the patient into this area. Before intubating, you will therefore tell everyone unnecessary to leave the operating room.


We now switch on fan ! It will blow air across the patients face.


As you intubate, the fan will push away from you, any aerosols, reducing the risk of you inhaling the virus. The virus concentration at the mouth should be low, making the airway manipulation safer.


Once intubated, you switch the fan off. The operation room air flow should dilute the viruses the fan pushed away and expel them over time to the exterior.


Once it is deemed that enough time has elapsed for the theatre airflow to get rid of the aerosols , the surgical team can come in and operate.


The same process can be done at extubation. Operating staff  leaves, the fan is switched on, and the extubation done. One the patient resumes quiet breathing, the fan is switched off. Once enough time has elapsed for the operating room ventilation to clear the virus, the rest of the staff can come back in if they need to.


This “Aerosol Diluting Fan” is just an idea. I would be grateful if someone will analyse it and perhaps take it further. Yes it looks low tech, but sometimes ow tech may well do the job ! If the idea is found to be sensible, then it should be easy to implement as these fans are quite cheap.

Fan motors do have sparks inside them, so do not use with explosive anaesthetic agents like ether !


You can let me know what you think at my email : web21(the at symbol)freshgasflow.com or leave a message at the Facebook post that brought you here.

Thanks

Pras