The Medical System works by adding a Blood Level, Oxygen Level, and Heart Rate that the player needs to be conscious of. These levels can decrease from injuries, and increase from various medical items added by the plugin. Some require another player to administer/use.
The specific attributes of Blood/Oxygen/Heart Rate are as follows.
Blood - Take damage and you'll start to bleed. If you begin to bleed, you'll see the blood bar become visible on your screen, and it will display how much blood you have. As your blood lowers, you'll notice attributes start to become hindered and your vision will get darker. You can increase your blood by using a Blood Bag, and you can stop bleeding with a bandage. However, keep in mind there are multiple levels of bleeding. At higher levels of bleeding (If you've been hit more than once) you'll need more than one bandage to stop the bleeding.
Oxygen - If you enter Cardiac Arrest, or are underwater, you'll loose Oxygen. Once oxygen starts dropping, you'll see your oxygen bar display your current oxygen level. Once the oxygen hits zero, you'll begin to take health damage. Oxygen can be increased, by another player using an oxygen mask on you.
Heart Rate - Your heart rate will increase or decrease based off your current activity. Bleeding will cause your heart rate to rise, and conversely increases the speed of your bleed out until you hit a high enough heart rate that you begin to enter cardiac arrest. When in cardiac arrest, a defibrillator can be used to normalize your heart rate. (Note, another player must use the defibrillator.)
Defibrillator - The defibrillator is a swep that the player equips, and requires a battery loaded into it to function. When a battery is loaded, the Defib can be used to restart the heart of a player whom is suffering from cardiac arrest, or can even bring a player back to life if they are dead, but still 'Respawning' and their body is zapped. The defib can also be used as a weapon of sorts, and when a healthy player is zapped, they will enter cardiac arrest, and be unable to do anything.
Oxygen Mask - Once loaded with an Oxygen tank, the Oxygen Mask can be used to give a player life saving oxygen, which is useful if they have been drowning, or are suffering cardiac arrest. As with the Defib Unit, the Oxygen Mask itself is a swep that requires you to aim and 'Shoot' the injured individual.
Bandages - The bandage item will overwrite your schema's bandage item (If it has one) and instead of providing heath, it stops bleeding. (Sometimes more than one bandage is required.) If it doesn't immediately halt the bleeding, it will at least slow down the rate at which the player is bleeding.
Blood Packs - A blood pack can be used on an individual who has lost a considerable amount of blood and will increase their blood level, potentially saving someone whom has suffered from massive bleeding. A blood pack can either be taken by yourself, or applied to an injured player.