CPR is a technique that has saved countless lives since the modern version was developed in the 1960s. However, it turns out it doesn't work very well in zero gravity, so a team of European cardiologists has been testing alternatives for astronauts.
Cardiopulmonary Resuscitation (CPR) is an indispensable bit of knowledge not only for the dedicated first aider, but the average citizen as well. So simple that just about anyone can learn to do it, CPR can literally mean the difference between life and death for someone having a cardiac arrest.
For untrained bystanders, the "handstand method" of CPR is the preferred technique according to the American Heart Association (AHA) and other health organizations. It's a simple technique that involves applying rhythmic pressure to the sternum through the hands using the rescuer's weight. This compresses the heart and keeps blood flowing until the heart restarts or professional help arrives.
It works extremely well, especially if you can remember the song "Stayin' Alive" to keep the rhythm, but in space, things are entirely different. In zero gravity, there's no weight to bring to bear and the rescuer just bounces off the patient's chest, so some other method is needed.
To evaluate alternatives, cardiologists teamed up with the French space agency, the Centre National d'Etudes Spatiales (CNES), to conduct tests aboard an Airbus A310 aircraft modified to fly in parabolic arcs to simulate weightlessness for brief periods. During these floaty interludes, the team tested manual CPR and three types of automatic chest compression devices.
Such devices aren't very well known to the general public, but they're standard pieces of emergency equipment for applying CPR where there isn't enough room for the handstand method, such as in the cramped confines of a medivac helicopter, or when CPR has to be applied for a very long time. This can be done by a frame with a piston, a more compact piston device, or a portable strap-on compression band.
The goal was to see which of these methods could compress the simulated chest to a depth of 50 to 60 mm (2 to 2.4 in). What they found was that where manual CPR failed, the standard mechanical piston device could reach the required depth.
"We tested different ways of giving chest compressions aboard a 'flying laboratory,' which recreated the microgravity conditions that astronauts experience in space," said Nathan Reynette from the Cardiology Department at Université de Lorraine – CHRU de Nancy. "Use of a particular type of automatic chest compression device was the only method that gave the depth that is recommended by international resuscitation guidelines to keep blood flowing to the brain in a real life cardiac arrest. We hope that our findings will be incorporated into the next guidelines for treating cardiac arrest in space."
Since astronauts are chosen for physical health, the chances of a heart attack case are pretty low, but as the cost of space travel continues to drop radically, more members of the general public will certainly be heading for orbit in the near future. In addition, the technology could be used to save lives aboard submarines and at remote Arctic bases.
Source: European Society of Cardiology
