NASCAR champion Kyle Busch’s cause of death at 41 was confirmed by his family as severe pneumonia that progressed into sepsis. “The medical evaluation provided to the Busch Family concluded that severe pneumonia progressed into sepsis, resulting in rapid and overwhelming associated complicati ons,” a statement from the vice president of Kyle Busch Companies explained. “The Family asks for continued understanding and privacy during this difficult time.” On May 21, Busch’s family announced his sudden passing in a joint statement with NASCAR and Richard Childress Racing. “Our entire NASCAR family is heartbroken by the loss of Kyle Busch,” the statement read. “A future Hall of Famer, Kyle was a rare talent, one who comes along once in a generation. He was fierce, he was passionate, he was immensely skilled and he cared deeply about the sport and fans.” “During this incredibly difficult time, we ask everyone to respect the family’s privacy and continue to keep them in your thoughts and prayers. Further updates will be shared as appropriate.” Busch is survived by his wife, Samantha, and their children, Brexton and Lennix. Here’s what was shared about his health prior to his death. NASCAR May 23 Kyle Busch died of severe pneumonia, family says NASCAR May 22 911 call reveals Kyle Busch was coughing up blood, short of breath day before death NASCAR May 22 Kyle Busch was more than a ‘villain' and the greatest NASCAR driver of his generation Kyle Busch’s cause of death Kyle Busch’s cause of death was pneumonia, which led to sepsis. Pneumonia is a type of infection that causes the air sacs in the lungs to swell up. Pneumonia can be caused by bacteria, fungi or viruses. Sepsis, a life-threatening condition, occurs when the body’s typical immune response to an infection turns and causes the organs to work poorly. Sepsis can progress to septic shock, when blood pressure drops and leads to organ failure and in some cases death. What is sepsis? A doctor explains “Sepsis is not the infection. Sepsis is the body’s overwhelming response to the infection,” Dr. John Torres, NBC News medical correspondent, explained on TODAY. “The immune system kicks into overdrive, and it starts affecting the organs and other parts of the body, and that’s what ends up being deadly.” Any infection can turn into sepsis, so it’s important to recognize the signs, he added. The Sepsis Alliance uses the acronym TIME to help identify them. T: A higher or lower temperature than usual I: Signs and symptoms of infection M: Mental decline, such as feeling sleepy or confused E: Extremely ill, including severe pain and shortness of breath Early intervention in sepsis can help increase the chances of survival, Torres says. People do recover, but many have lifelong conditions as a result. Children, elderly people and those with compromised immune systems appear to be at higher risk. However, “there’s a lot we don’t know about sepsis,” Torres says. “We do know that treatment is paramount, and treatment early is extremely important time.” Kyle Busch’s health before his death On May 10, Busch made a radio call during a race to request medical assistance, according to an audio clip that Fox NASCAR shared on X. During the clip, an announcer mentioned that Busch had been experiencing a “sinus cold” all week. Then, Busch can be heard asking to see a doctor after the race. “I’m going to need a shot,” he said. On May 15, Busch won his final race at the ECOSAVE 200 at Dover Motor Speedway in Dover, Delaware. After the race, he spoke with Fox NASCAR and described why winning a race never gets old. “You never know when the last one is,” he said, in part. May 16 footage of an interview with Busch conducted by Jeff Gluck, a reporter for The Athletic, showed him talking about his symptoms. “You can kind of still hear it. I’m still not great. But the cough was pretty substantial last week,” Busch said. On May 20, the Associated Press reported that Busch became unresponsive while he was testing in a Chevrolet racing simulator. He was then transported to a hospital. According to a 911 call obtained by NBC News from that day, Busch coughed up blood and was lying on the bathroom floor when they called for help. The driver, who was at a General Motors training facility in North Carolina, per the call, also expressed “shortness of breath” and was “very hot.” “I’ve got an individual that’s, uh, shortness of breath, very hot, thinks he’s going to pass out and is producing a little bit of blood — coughing up some blood,” a man said around 5:30 p.m. on May 20, a day before Busch’s death. The man added that, at the time, Busch was “awake” and “on the bathroom floor.” On May 21, Busch’s family issued a statement announcing that he would not be competing at the Coca-Cola 600 at Charlotte Motor Speedway. “Kyle has experienced a severe illness resulting in hospitalization. He is currently undergoing treatment and will not compete in any of his scheduled activities this weekend at Charlotte Motor Speedway. We ask for understanding and privacy as our family navigates this situation,” the statement read. Busch’s death was announced later that day. What Busch’s family has said following his death While announcing Bush’s death, the NASCAR driver’s family extolled his successful racing career. “Throughout a career that spanned more than two decades, Kyle set records in national series wins, won championships at NASCAR’s highest level and fostered the next generation of drivers as an owner in the Truck Series. His sharp wit and competitive spirit sparked a deep emotional connection with race fans of every age, creating the proud and loyal ‘Rowdy Nation,’” the statement reads. Racing runs in the Busch family. The late NASCAR driver followed in the footsteps of his father, Tom Busch, and his older brother, Kurt Busch. The late racer’s son, Brexton, is also continuing the family legacy. This story first appeared on TODAY.com. 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