When a crewperson is dead, you use your advanced cardiac life support certification that you earn so hard from training but also revive them with a Defibrillator. The process of using it boils down to the following steps:
First, you need to assess the priority of your target. When using a MedHUD, their death “stage” will show on the top right of their sprite. This indicates how much time you have left before they're permanently dead.
Yellow Bolt: Indicates that a target is newly dead. If they've just died, you'll have around 5 minutes to shock them back to life.
Orange Bolt: Indicates that the target has less then 3 minutes before going permanently dead. Use this as a sign of caution, and try to keep people from hitting this stage.
Red Bolt: Indicates that a target is long deceased. If you're seeing this, you yell to your nearest marine to do CPR since you have less than a minute to revive them before-
Skull: Indicates a target is permanently dead. Either they've been dead for longer than 5 minutes, have a DNR, or otherwise have some condition preventing revival.
This is their armor/hazard vest/lab coat/spacesuit or whatever else is occupying their exosuit slot. The Defibrillator machine will tell you that the voltage is too high and to take off their suit (some exosuits don't need to be taken off though).
The next couple of steps are the changeable ones. The defibrillator's inactive states have the paddles folded over, while its active state shows the electric charge. Always keep it active in your storage! You have time during prep to turn on the defibrillator.
It'll either work or it won't. If it does, great! Get to fixing them as best you can. There is also a 25% chance for 5 units of heart damage. This will make them have a baseline 20 units of oxygen damage if you fix everything else wrong with them. If the oxygen damage is persistent, use peridaxon to prevent the symptoms of heart damage.
How dead are they? To revive patients, their health must be lower than 200 total damage, where total damage is the summation of oxygen, toxin, brute, and burn damage. If the patient has a lot of Brute damage, you've got to patch those holes with an advanced brute kit. If the patient has a lot of Burn damage, use advanced burn kit. Advanced kits help with getting the patient's total damage lower than 200. Patients do not heal with pills as they need to be alive to metabolize pills.
This is the most important step. Applying an Advanced Brute for brute damage or Burn kit for burn damage to a limb will heal a significant amount of damage even if the patient is already dead. You don't have to be wasteful, just target the biggest wounds and get the damage below 200, then move on to the next step. If their entire body is damaged, i.e. by fire or an acid cloud, this can use up a lot of resources.
After they are revived, it's important to reduce the damage that brought them to death. Skip this step if they're close to going braindead. A successful revive resets the timer, even if they die two seconds after.
So you've shocked them and the defib reads that the patient's vitals are too low. But, you've already pumped them full of drugs and patched up all their wounds. Well, you're in luck! The machine heals some damage based on your medical skill (as well as all oxygen damage) with every defib charge spent. Therefore, keep shocking them until they aren't dead anymore. The drugs will usually kick in at that moment and they should stay alive.
Health per job:
Be aware that using the defib deals organ damage to the heart. Therefore, you should only be doing repeated shocks if the patient is close to the revival threshold. Otherwise, use medical surgical sutures to repair large amounts of damage.
This step only works for already-living patients, dead ones can't be put into any machines. The cryo tube will heal all types of damage, even long-term damage like internal bleeding and cellular damage, for as long as they're inside it. The autodoc can heal anything except cellular damage, and the only resource it spends is power, but make sure the Medbay APC doesn't drop below 30% or everything in the room will stop working! Either of these are great options for fixing whatever made them dead in the first place, as well as the crippling heart damage you inflicted upon them by shocking them ten times.
We've got the steps now; Depending on how you're feeling, you can order them in a few different ways:
and if that doesn't work:
But that's not the only way to do it.
There's also a much more wasteful way:
So, in short, it breaks down to get them below 200 total damage, fill them with drugs and first aid to keep them from getting worse, then do surgery as required.
Toxin damage is the most dangerous because there isn't an easy way of removing it from a patient. The Sleeper dialysis doesn't remove toxin damage; it only removes chemicals. If you need to remove toxin damage you have to use Toxin Damage Chelation from the autodoc (which only works on live patients). Therefore, if you've got a patient with 200 toxin damage, all you can do is keep shocking.