What happens when you get sick or injured
in space, thousands of miles from the nearest
hospital?
Space flight is incredibly risky and an astronaut
getting sick might mean they don't survive
the mission.
So how does NASA prepare for these situations?
Earlier this year, I came across a letter
to the editor of the New England Journal of
Medicine.
In that letter, some NASA scientists told
the story of how an anonymous NASA astronaut
was found to have a clot in the internal jugular
vein of the neck during a spaceflight mission.
The internal jugular vein is the largest vein
in the neck and it drains blood from the brain
and face.
This particular astronaut was participating
in a study where they were using ultrasounds
to investigate fluid shifts in spaceflight.
The ultrasound pictures were sent to Earth
and to the surprise of two radiologists at
NASA, they found there was a huge thrombus,
or blood clot, partially occluding the vein.
The strange thing is that the astronaut didn’t
have the usual risk factors for blood clots
to occur.
In medicine, we talk about Virchow’s triad
to describe the causes of a thrombosis.
The triad consists of injury to the blood
vessels, hypercoagulability and reduced blood
flow.
Hypercoagulability occurs in people with congenital
clotting disorders, cancer, sepsis and in
pregnant mothers or smokers.
In this case, all those things were unlikely
so we can rule them out.
Also, there probably wasn’t any injury to
the blood vessels as that usually occurs from
trauma, surgery or chronic hypertension.
However, since the astronaut wasn’t experiencing
any gravity, there was less blood draining
from the head back to heart.
As a result, the blood in this astronaut’s
internal jugular vein was stagnant and when
that happens platelets in the blood are more
likely to clump together and form clots.
On Earth, this often happens in the legs when
people are bed bound after surgery or on a
long-haul flight.
The clot in the legs can travel to the lungs
and cause something called a pulmonary embolism,
or PE for short.
If it’s big enough, PEs can be life-threatening
because the clot blocks blood from reaching
the lungs and carrying oxygen to the rest
of the body.
So in the NASA astronaut, because of the lack
of gravity and lack of blood flow, NASA doctors
were worried that the same thing would happen
where the clot travels to the lungs and causes
a PE.
The other possibility is that the clot could
grow and extend upwards into the brain and
block blood flow that way, effectively causing
a stroke.
When an astronaut gets an emergency medical
problem aboard the International Space Station,
their first option is to throw that astronaut
into a space capsule and fly them back to
Earth.
However, if our astronaut with the blood clot
was flown back to Earth, it would cause a
lot of turbulence and G-forces which could
lead to bits of the clot breaking off and
causing a pulmonary embolism.
Luckily there was a 40-day supply of an injectable
anti-clotting medication called enoxaparin
on board the ISS.
NASA also decided to send a resupply vehicle
to the ISS to deliver more oral anti-clotting
medications.
What’s crazy is that when the astronaut
landed back on Earth 6 months into his mission,
normal blood flow resumed in the vein and
the clot disappeared within 10 days.
This brings us to challenges of medical care
in space.
Just as one example, the zero gravity environment
means that bubbles don’t float to the top
in fluids or liquid medications.
It makes drawing up medications difficult
and if you draw up air you could potentially
inject that into the veins causing a pulmonary
air embolus just like what we were talking
about before but with air.
Even seemingly simple things, like giving
IV fluids requires gravity for the fluid to
flow, so in space you would need to physically
pump it into the veins.
If there’s an acute medical condition like
appendicitis in space, the astronaut needs
to be flown back to Earth as soon as possible.
Or the astronauts might need to perform surgery
with the help of an Earth doctor through video
call maybe.
However, performing emergency surgery in space
has it's own problems.
Once the body is opened, blood and other fluids
will form little bubbles because of surface
tension and these bubbles float around and
can disrupt equipment or block the surgeons
view.
One paper proposed an idea where they used
an air-tight dome over a body cavity to give
the person doing the surgery a clear view
of what's going on inside without letting
fluid escaping.
The dome is flexible and the astronaut could
make small holes to basically do keyhole surgery
much like how it’s done on earth.
In fact, NASA funded an experiment where they
put surgeons on something called a parabolic
flight which is a plane that sort of falls
towards Earth for a short duration just to
simulate the zero-gs.
They asked the surgeons on the parabolic flight
to perform laparoscopic surgery on animals.
What they found was that it is was no harder
than doing surgery in a normal 1-g environment.
In fact, there’s heaps of other studies
that have demonstrated that it’s entirely
possible to do things like microscopic surgery,
intubations, vascular surgery and a bunch
of other weird and wonderful procedures in
zero-gs.
However, then it becomes the problem of how
you’re going to transport all that surgical
equipment up to space when it costs about
$10,000 per pound to launch that cargo.
One possible solution is to use 3D printers
to print out the instruments when they’re
needed but as you could imagine this comes
with its own problems like lengthy printing
times.
And secondly, you have to train your astronauts
to be able to perform these surgeries which
is no easy feat.
Scientists have also proposed the idea of
robot surgeons, like if there was a surgeon
on Earth controlling a robot in space.
NASA actually tested this by performing a
gallbladder removal operation where the surgeon
controlled a robot 14km away in an underwater
facility.
This might work for missions close by like
in the ISS but for spaceflights that are further
away, the lag time for the information to
travel might be too much.
So you might be thinking, why don’t we just
remove everyone’s appendixes and gallbladders
before they go up into space?
At the moment for astronauts in the ISS, flying
back to Earth can be done relatively quickly
so it’s probably not worth it.
However, there’s a study done in 2012 which
says the astronauts going on long-haul flights,
say to Mars, might actually benefit from having
their appendixes or gallbladders removed.
Emergency medical care in space poses a huge
challenge.
We might not even fully understand how our
bodies will react to surgery in zero-gs considering
there’s a lot of fluid shifts and hemodynamic
changes that go on in space.
You know, space does some crazy things to
your body.
First we found that it causes your bones and
muscles to waste away, then it became problems
with your heart deconditioning.
Only within the last 10 years we found out
about this thing called spaceflight associated
neuro-ocular syndrome where astronauts’
have deteriorating vision because of physical
changes to their retina and optic nerves.
Finally, this time last year, we didn’t
even know that astronauts could be developing
these huge clots in their necks.
All this is to say is who knows what other
healthcare challenges lie ahead for future
astronauts.
One thing is for certain though, and that
is science will keep evolving to overcome
these obstacles and push humans to places
we’ve never been before.
