Smoke inhalation is a major cause of death after fires.

By Sarah Klein
February 05, 2018

Only one group of TV viewers may have been sadder than Patriots fans on Super Bowl Sunday… devoted This Is Us watchers finally got an answer to how much-adored patriarch Jack Pearson dies.

We already knew about the fire caused by a Crock-Pot on the fritz from the previous episode. But Sunday's episode finally put all the puzzle pieces in place: Jack doesn’t actually die in the fire. After awakening to the house ablaze, in a superhero-esque act of fatherly devotion—we’d expect nothing less from him—Jack gets his family out of their burning home and then goes. back. in. to save the Pearsons’ adorable little dog Louie.

RELATED: ‘This Is Us’ Showed How Debilitating and Scary an Anxiety Attack Can Be

Remarkably, he returns safely—but is whisked to the hospital for treatment for burns and smoke inhalation, where we start to believe everything is going to be fine. Rebecca leaves the room briefly, and then it happens: Jack enters cardiac arrest and dies.

"One of the complications of is that it puts terrible stress on the lungs and therefore the heart. Your husband went into cardiac arrest. It was catastrophic, and I’m afraid we’ve lost him," the doctor tells Rebecca.

Bleary-eyed and heartbroken, we’re left wondering—how does this happen? And could Jack have been saved?

RELATED: What Is Cardiac Arrest–and How Is It Different From a Heart Attack?

Cardiac arrest—while under the umbrella of heart disease—comes on suddenly. It’s caused by an electrical malfunction that stops the heart from beating. And of course, when your heart isn’t beating, blood isn’t being pumping around your body. That lack of blood means a lack of oxygen, leading to loss of consciousness and—without emergency treatment—death.

Typically, cardiac arrest risk factors are the same as those that put a person at risk for any heart problems, like high blood pressure or cholesterol and a family history of heart disease or cardiac arrest.

But smoke inhalation is a bit of a different story. "Smoke inhalation is suspected to be the cause of 75% of all fire-related deaths in the U.S.," writes pulmonologist , co-director of the Asthma Center at Cleveland Clinic to Health in an email. There are a number of different ways it can lead to death, "all stemming from a lack of oxygen to the arteries that supply the heart with oxygen and lack of oxygen delivery to essential organs," she says.

Smoke inhalation can injure the throat, making it literally so difficult to breathe that a person could actually suffocate, Dr. Khatri explains. Breathing in smoke can also cause carbon monoxide poisoning, which "starves the body of the oxygen it needs to function," she says, which could lead to a heart attack (perhaps what Rebecca meant when she later commented that Jack’s death was caused by a ?). Smoke inhalation from a house fire might cause cyanide poisoning due to compounds created from the burning of furniture made with materials like rubber, wool, and foam, Dr. Khatri explains. The lack of oxygen caused by cyanide poisoning could also lead to cardiac arrest.

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Whatever the outcome of smoke inhalation, "treatment must be delivered quickly," Dr. Khatri says. Time must have run out for Jack. While we don’t see what exactly happens in that hospital room while Rebecca steps out for a candy bar, cardiac arrest is often treated with CPR and a defibrillator that can shock the heart back to a normal pumping rhythm.

At least fans don’t have long to wait for closure—hopefully. The next episode airs back at the show’s regular time on Tuesday. This Is Us creator Dan Harmon has promised Entertainment Weekly that "There is a bigger story here than just how Jack dies."