ICU

ICU ("Intensive Care Unit") is a Resistance perk featured in Call of Duty: Ghosts. Players equipped with this perk will half both the delay before their health begins to regenerate, and the time it takes to regenerate to full health once it starts.
Although not mentioned in the perk description, tactical grenades' effects will not last as long when ICU is equipped. This is perhaps due to the partial damage taken from tactical grenades is eradicated quicker by ICU.
In Safeguard, it is referred to as "Fast Health Regen". 
As ICU pertains to health regeneration, it is useless in Hardcore game types, where health regeneration is entirely disabled. ICU can be very helpful in custom game modes where the rate of health regeneration is modified. If the health regeneration rate is made slower, ICU will counteract this. If the health regeneration rate is made faster, ICU can make the user very hard to catch at low health.
Due to ICU's properties, it is very useful for an aggressive user, as aggressive users have less opportunities to hang back and regenerate their health. ICU is less useful for passive, defensive players, as they can simply hide behind cover to give ample time to regenerate health, although ICU can still help defensive players by allowing them to re-peek more quickly as the extra healing rate will enable users to wait less before they have full health. For aggressive users, they will still need to give ICU a chance to start its health regeneration, as a user who simply enters combat before health regeneration can take place will find ICU to have little benefit.
Category:Call of Duty: Ghosts Resistance Perks