Pulmonary Surfactants

I came across pulmonary surfactants because I keep thinking about surfactants and Coronavirus. The Coronavirus is made up of a strand of RNA surrounded by a lipid membrane with little protein spikes sticking out of it like a crown (or corona).

Soap and washing-up liquid break up the lipid membrane that surround the Coronavirus. That’s how they destroy it. So I was thinking about people with COVID-19 respiratory inflammation and wondered whether it might be possible to wash out their lungs.

I googled and found that pulmonary surfactants are part and parcel of lung design. Here’s a quote from an article about surfactant in asthma:

Pulmonary surfactant with an optimal function in the airways is important because it stabilizes the conducting airways, prevents fluid accumulation within the airway lumen, improves bronchial clearance, acts as a barrier against the uptake of inhaled agents and has important immunomodulatory properties. In asthma, it has been demonstrated that there is a surfactant dysfunction mainly due to inhibition by proteins that enter the airways during the inflammatory process

The Coronavirus is small

Human hairs vary in thickness. Chinese, Japanese, Thai, and Korean hair is about 90,000 nm in diameter. Indian and Spanish hair is about 80,000 nm in diameter. European hair is about 70,000 nm in diameter. 

There are one billion (one thousand million) nanometres (nm) in one metre.

The Coronavirus family varies in diameter from 80 – 160nm. This Coronavirus (severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2 or the Covid-19 virus) is 125nm in diameter

So approximately 560 Covid-19 viruses laid side by side would be about the same width as a typical European hair.

How Far Does The Virus Travel

So if someone sneezes, does the virus fall to the ground in a gentle arc, bound up in sneeze droplets? Or does it get wafted away on the wind? The consensus seems to be that staying two metres from another person isolates you from them. Does that apply if they sneeze or cough in your direction?

Does it suggest infected people have a miasma of viruses in the air around them that tapers off to nothing within two metres? There have been several studies, criticised for not being real-world studies, showing how far the virus can travel. In a worst-case scenario, two metres seems nowhere near far enough.

A few weeks ago on TV I saw a Sky News report with the reporter driving around the medieval city centre of Bergamo in Lombardy in Italy. Bergamo was the epicentre of the Italian outbreak. The streets were narrow and the buildings were tall. I could imagine the air recirculating in the streets, full of virus.

Viral Load

Which leads to another thought, that the severity of the effect is dependent on the viral load. The more viruses one takes in, the more the chance they will overwhelm the body before it has chance to develop antibodies.

It also explains or suggests why nurses and doctors who are young or otherwise healthy are dying from COVID-19, namely that they are coming into contact with large quantities of the virus.

There’s a YouTube video I saw of people at a New York hospital explaining how they have rigged up negative pressure rooms in the hospital with negative pressure cages around the patients’ beds. They put large-bore tubing leading from the rooms, out of the windows and up to extractor fans with filters on the roof.

That directs virus-laden air out of the rooms and limit the risk of exposure to nursing staff. Additionally, the cages around the patients pull the virus-laden air that patients expel, away from the patients and out of the rooms. It seems sensible and logical to think that viruses rotating around a patient’s mouth and nose would be sucked in again unless swept away.