Hello all - first and foremost thank you to anyone who is able to take time to respond. I'm looking for some guidance and trying to understand if tis is a common death in dogs or was there any way to potentially avoid it.

I recently posted on r/petloss with more of the story of how I got this dog, but long story short I got him about a year ago from a shelter and he was already fixed and UTD on shots. We took him into our regular vet on March 9th for a checkup and the only thing she noted was that he was a little bit skinny (made sense at the time - he wasnt eating in the shelter). We took him for an appoint on October 10th and got a clean bill of health. On November 4th, Balto started showing some signs of distress after eating his breakfast. He had laid back down in his crate but then started crying and dragging his back legs. We rushed him to an emergency vet where he was ultimately diagnosed with a diaphragm hernia - the scheduled surgery for November 6th.

I spoke with the surgeon when I dropped him off who coincidentally also had a diaphragm hernia at birth, and also did her residency under the Dr who performed a hip replacement on our other dog. I felt really good about it and we spoke mostly about what the recovery would look like. Less than 4 hours later Balto was dead. The surgeon called when he was out of surgery and said that his liver was twisted / firm and dark purple. His entire intestines' was in his chest cavity along with his spleen. They removed the spleen when moving everything back to the abdomen because it didn't fit. She said he was starting to come out of anesthesia but his legs were cold and tongue was blue-ish and he didn't have the correct pulse.

She called again ~10 minutes later and said he was in cardiac arrest and they were performing CPR but he was not going to make it.

After this, the vet mentioned his true cause of death was reperfusion injury. She sent me the following text to help explain it:

"Reperfusion injury refers to a cascade of events occurring at the cellular level in response to the sudden reintroduction of highly oxygenated blood into an anaerobic (no oxygen) environment. As the oxygen returns, there is generation of a large number of free oxygen radicals and other highly reactive compounds. These compounds have a short half-life and are unstable. They are generated and interact immediately with cells. This interaction can severely damage cellular integrity and generate more free radical molecules.
This situation is important in chronic diaphragmatic hernia management because reexpansion of chronically atelectic lungs and restoring blood flow to chronically compromised portions of liver or gastrointestinal tract results in generation of free radicals. Conditions such as reexpansion pulmonary edema and liver shock, reported as complications of chronic diaphragmatic hernia repair, may be fatal."

I found the textbook that she quoted, and the wording is slightly different. The textbook says the following - bolding and emphasis mine.

9. Discuss reperfusion injuries. Reperfusion injury refers to a cascade of events occurring at the cellular level in response to the sudden reintroduction of highly oxygenated blood into an anaerobic environment. As the oxygen returns, there is generation of a large number of free oxygen radicals and other highly reactive compounds. These compounds have a short half-life and are unstable. They are generated and interact immediately with cells. This interaction can severely damage cellular integrity and generate more free radical molecules. Only by reacting with a free radical scavenger is the cycle interrupted.

This situation is important in chronic diaphragmatic hernia management because reexpansion of chronically atelectic lungs and restoring blood flow to chronically compromised portions of liver or gastrointestinal tract results in generation of free radicals. Conditions such as reexpansion pulmonary edema and liver shock, reported as complications of chronic diaphragmatic hernia repair, may be blunted by careful consideration of the potential for reperfusion injury. No single method is effective in preventing or managing reperfusion events in patients. Medications, such as steroids or free radical scavengers, and management practices, such as lobectomy for severely compromised liver lobes and slow gradual reinflation of compromised lung tissue over several days, may decrease the severity of reperfusion injury.

I guess my question is - was there something missed? What question do I need to ask the surgeon to help understand that they did everything they could to prevent this from happening? Is reperfusion injury a common death reason for correcting a diaphragm hernia in dogs?

Thanks for any help / advice that anyone can offer.