Septic shock is more common than what you may think. It happens when a bacterial or fungal infection spills into the bloodstream.
This causes severely low blood pressure and the body becomes unable to circulate blood to the organs.
In the Pope's case, a urinary infection lead to sepsis. Experts say for people who already have medical problems, the chances of beating sepsis may be slim.
It is not a painful condition as patients usually lose consciousness. Once the organs fail, the heart will eventually stop.
Sepsis is treated with antibiotics to try to curtail the infection, but in many cases the damage may be irreversible.