What I do when holding breath becomes an issue is to use the PHB rules for how many rounds of air the creature has. Whenever the creature uses an action or takes damage an additional round of air is used up. So a Con 10 creature needs to think about getting out of the water instead of initiating combat underwater. If the Con 10 character fought underwater, their air could be exhausted after 1 or 2 rounds of attacking and taking damage.
Going back to the original question of strangulation, each time the creature ends a turn while being strangled, another round of air is lost. So between using an action to attempt to escape the grapple, taking a knee or a head butt, and ending a turn while being strangled, the air can get lost quickly.
Going back to the original question of strangulation, each time the creature ends a turn while being strangled, another round of air is lost. So between using an action to attempt to escape the grapple, taking a knee or a head butt, and ending a turn while being strangled, the air can get lost quickly.
