Defibrillators in space; how do astronauts perform lifesaving treatment in zero gravity?


‘Defibrillate with care’ is how space physician Kevin Fong would describe it.

With space travel being covered in the news ever so slightly more now that British astronaut Tim Peake is aboard the International Space Station, we began to think about the complications and difficulties that must be present when attempting to provide first aid, CPR or even defibrillate in space.

And boy were we right to think it must be complicated.

Just like any other small, mundane task here on planet Earth that becomes much more difficult in outer space, performing life-saving treatment becomes increasingly difficult. And it definitely doesn’t fall into the ‘small and mundane tasks made hard’ category.


Chest compressions

Unless things are strapped down in space, they are going to start floating away. The same can be said of someone who has suffered a cardiac arrest and in need of immediate CPR and chest compressions.

Astronauts would have to strap the patient to floor whilst the person who is providing compressions would need to be fastened to the patient to allow constant and rhythmic compressions. Alternatively they would need to jump up with feet on the ceiling and propel themselves to push down on the patient’s chest. It’s a challenge.

NASA says: ‘The likelihood of cardiopulmonary resuscitation (CPR) being performed in space exploration is very low but not non-existent. CPR in microgravity is most reliably performed in the handstand position and meets AHA guidelines for closed chest compression depth.




In space, the application of a defibrillator is not so much a problem – it’s the electric current that poses an obstacle:

‘In space, other crew members are floating around and astronaut chairs could be conductive – if you need to defibrillate [or shock] the patient, the question is how do you do it without shocking everybody else around you?’ – ‘Special defibrillators have to be used, so they don’t interfere with the electronics of the space station.’

To ease the logistics of using a manual defibrillator in space, NASA announced in 2008 the Lifepak 1000 defibrillator as being deployed on the International Space Station (ISS) as the first automated external defibrillator (AED) in space.

They conducted extensive evaluations of 18 AEDs worldwide before selecting the Lifepak 1000 to protect the crew members of the ISS. Evaluations of the defibrillators included:

  • User interface analysis
  • Ease of use
  • Durability and detailed technical specifications related to the unique conditions encountered in space
  • Analysis and testing for electromagnetic interference, pressure susceptibility, temperature, vibration, acceleration and other environmental factors
  • Subjection to zero gravity testing aboard the NASA DC-9 test aircraft as part of developing their advanced life support use protocols

With the exception of a newly customised battery pack and a NASA-created cover for the device that is specifically designed for space use, helping to protect it from electromagnetic interference, the Lifepak 1000 was deployed on board the Space Station in the same device configuration used by first responders here on Earth.

The Lifepak 1000 returned to Earth on the historic final shuttle mission ‘Atlantis’ in July 2011 before being returned to Physio Control for testing and analysis in October 2011. In the video below you can see the unboxing of that defibrillator and the see the special casing developed by NASA to protect the unit.


Further treatment; return to Earth

According to Fong, the ISS has less medical equipment and expertise than an average London ambulance – ‘So you need to get them home as quickly as possible, which is tricky.’

Now if all the above seemed difficult, once you have the patient in a stable condition, they are going to require expert further treatment quickly, which can only be found back on home turf. The ISS orbits at 400km above the surface. That’s 254 miles. Problem.

When the astronauts return to Earth from the ISS, it takes 3 hours for the return capsule to undock from the ISS once the astronauts are inside.

2 hours, fifty-seven minutes after undocking from the ISS, the vehicle beings to cross the atmospheric boundary to rejoin Earth’s atmosphere. 3 hours, five minutes after undocking, parachutes deploy and 15 minutes later the capsule will make contact with the ground.

As a rough guide - an ordinary re-entry to Earth takes approximately 6 and half hours by our calculations.



It’s a tough task made even harder in space. So on top of everything else astronauts have to contend with during a mission to the ISS, they have to know CPR, first aid and how to use a defibrillator like the back of their hand in order to provide their colleague the best chance of survival in an emergency.

If you would like to learn more defibrillators, cardiac arrest, the heart and everything in between – our defibshop blog is packed full of useful information whilst our defibshop team are always ready on hand to help you find the right defibrillator to suit your needs – even if this includes space travel.

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