Dive Pacific 175 Dec2020 Jan 2021

DIVEMEDICINE
Why a diver should avoid Covid-19 and
what happens if they don’t
By Professor Simon Mitchell, University of Auckland
It is easy to run out of adjectives in describing this very strange year. “Unprecedented” is one you
hear quite a lot. The truth is most of the hyperbole is pretty well justified. The world has been
thrown into economic and social turmoil by the pandemic caused by SARS-CoV-2, and tragically,
a lot of people have lost their lives or livelihoods.
We in New Zealand have been
relatively lucky, though
to a large extent we made our
own luck. The early successful
lockdown was a testament to
both good leadership and highly
commendable buy-in by the kiwi
public at large.
As a sharp end medical practitioner
(an anaesthetist) I for one
am deeply grateful. I was on the
intubation team tasked with
putting very sick covid patients on
ventilators at Auckland Hospital.
We were envisaging Italy or
the USA or the UK here, and it
simply never happened. Indeed,
although we intubated a number
of suspected cases, not a single
one actually turned out to have
the virus.
The fact that we eliminated that
outbreak and several subsequent
ones from the community should
be a source of great pride. It may
not last, but let’s hope it does.
I say let’s hope it does because
contrary to early opinions, this
disease is not as forgiving as
many had assumed it to be.
Unforgiving
Early in the pandemic, outcomes
following covid-19 infection were
often portrayed as binary: you
either died, and that was rare,
or you lived, by far the most
common outcome, allegedly
without any problems. “In most
people its just like a common
cold” was an opinion often
expressed.
No. Its. Not.
This is a far more serious disease
…Sicker patients can also develop other strange manifestations,
like a tendency for blood to clot more easily. This has led to
events like strokes, sometimes in young patients. Some patients
also seem to develop a virally induced weakening of their heart
that leaves them with markedly reduced exercise capacity…
than the common cold, or influenza.
Yes, it remains true the
vast majority of people survive
Covid-19, but depending on how
complications are defined, a large
proportion of survivors suffer
them, and if you are a diver some
of those complications could be of
substantial significance.
Massive inflammatory/immune
response
In some respects, Covid-19 is a
typical respiratory virus. Early in
an infection it produces cold-like
upper respiratory tract symptoms,
albeit with some unusual variations
like loss of taste or smell.
Later, it can spread to the lower
respiratory tract producing a
pneumonia-like disease typically
involving both lungs. Nothing
particularly unusual there, but
this is where things can begin to
go off the rails.
In some patients, but not others,
spread to the lungs appears to
elicit a massive inflammatory/
immune response that, simply
put, does more harm than good.
The lungs can become extremely
congested with inflammatory
material making breathing difficult
and oxygenation increasingly
inefficient. This is when patients
sometimes require intubation
and ventilation, though the
more recent trend is to have a
higher threshold for doing that.
Experience has shown us that
patients can do better if we can
avoid mechanical ventilation.
Clinicians are getting more accustomed
to tolerating moderate
degrees of hypoxia and trying to
nurse patients through without
intubating them.
The sicker patients can also
develop other strange manifestations,
like a tendency for blood
to clot more easily. This has led
to events like strokes, sometimes
in young patients. Some patients
also seem to develop a virally
induced weakening of their heart
that leaves them with markedly
reduced exercise capacity.
Given that we have only been
dealing with this disease for a
short time, we don’t understand
the natural history of this complication.
Patients may recover, but
may not; only time will tell.
Change in the lungs
From a diver’s point of view the
most concerning complication
is medium to long-term change
in the lungs. Covid-19 appears
capable of producing sustained
changes in the lungs, call it
‘scarring,’ for want of a simpler
description, that the patient may
never recover from.
Again, the natural history of
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