I have created a script which when the player is shot or injured, he/she will bleed to a certain extent. Also, when you are healed by a field hospital or a medic, instead of recovering instantly, the player regenerates over time (anywhere within a minute). The level of bleeding is dependent on the parameters.
Also I have included a Health gauge will full information about the players current health, bleeding rates and mortality status. This uses the hint function, so you don't have to use it. There is a parameter for whether or not you want the gauge to show at all.
Also I have included a med kit script as a separate entity. It works very well with the healing and bleeding script, as it is designed to make life a bit easier when your dying of loss of blood, but you can also use it on it's own if you choose.
A full readme has been included, along with explanation of the various functions of the scripts and a detailed explanation of the mathematics behind the the healing and bleeding script.
See attached for download.