NFL

The on-field cardiac arrest of Buffalo safety Damar Hamlin traumatized some players and underscores the need for more consistent support in a league whose athletes are trained to show no weakness.

Before being flown to Buffalo, N.Y., Hamlin had been treated for nearly a week at the University of Cincinnati Medical Center after going into cardiac arrest on the field during Monday Night Football.

Doctors say they are still unsure what caused Hamlin's collapse during the Monday Night Football game against the Cincinnati Bengals a week ago.

For the more than 350,000 Americans each year who suffer cardiac arrest outside of a hospital, the prognosis is not always an optimistic one. But quick action with CPR and a defibrillator can be key.

Physicians interviewed by AP say there's no evidence Damar Hamlin's emergency was caused by his vaccine status, adding that there's been no increase in cardiac arrests among vaccinated athletes.

Dorrian Glenn said there were some encouraging signs in Damar Hamlin's condition, such as doctors lowering the level of oxygen needed from 100% to 50%.

It involves the impact of a specific force to the chest at a specific moment in the cardiac cycle. One cardiologist told NPR that what happened to Hamlin was likely "a perfect storm of events."

A list of some in-game or in-competition medical events that either suspended or postponed the competitions in which they occurred:

LISTEN: The Bills said Hamlin had a cardiac arrest after a hit. NPR's Rob Schmitz talks to Dr. Christopher Madias of the Cardiac Arrhythmia Center at Tufts Medical Center, about the effects of the blow.

The Monday night game between the Buffalo Bills and Cincinnati Bengals was suspended after Bills safety Damar Hamlin collapsed on the field.