Under Injury and Healing in nWoD 2e (Chronicles of Darkness):
if a character has all her Health boxes full of lethal damage — she’s bleeding out. She can’t recover from that without urgent medical attention and emergency surgery.
It also says
When a character’s rightmost Health box has lethal damage marked in it, he takes another point of damage each minute (upgrading existing lethal damage to aggravated) until he receives medical attention, mundane or supernatural.
Then the section on the application of medical attention says
The Medicine Skill can be used to speed up healing. Medical care is an extended action, requiring successes equal to the total number of points of damage suffered by the patient. In the field or ER, the dice pool is Dexterity + Medicine, and the interval is one minute. In long-term hospital care, the pool is Intelligence + Medicine, and the interval is one hour. Usually, any Conditions from a failure afflict the patient rather than the caregiver, but this is at Storyteller discretion.
Achieving sufficient successes restores one Health point lost to bashing damage, in addition to any healing that the character already does under his own power.
...But it seems to exclusively focus on speeding up healing, not the case of arresting impending death. Skipping the part about more long-term hospital care, it only mentions healing some bashing damage (presumably talking about the field/ER case). So it seems to be missing some details that seem important in a potentially tense, high stakes race against the clock like this, considering that both the interval for field care is one minute and a dying patient's damage also worsens every minute.
- Does the bleeding out and dying stop when you begin field care, because they're now receiving "medical attention," or are they only stabilized after accumulating the full number of required successes (equal to their number of Health boxes in this case)? The only explicitly listed effect of achieving all those successes is healing bashing damage, which by definition a dying character will not have.
- The timeline: if a character begins bleeding out at minute 0, acquires their first (upgraded) aggravated wound at minute 1, and a medic accumulates enough successes to arrest bleeding at minute 7, did the patient end up with 7 aggravated wounds, or 6?