What are you supposed to do if a delirious patient becomes aggressive, attempting to get up, put in restraints with security and then they say they can't breathe?

This is oddly specific because it happened to a patient I was sitting. He was known for getting ornery and aggressive and they were already going to get softs on him. Shortly after he tried multiple times to get up, then eventually became verbally and physically assaultive with me. He was delirious, probably septic. His nurse and another came in to help and then they eventually just went with the leathers because it was getting very bad. Security was called. The leathers were put on.

That is when he said he could not breathe.

His head was raised, he had oxygen, and his sats were still stable at that point

Then about two minutes after, his sats were continually in the 80s despite NC at 4. We called rapid response. As they were working him over his sats continued to drop. He went into respiratory arrest and from outside his room (i got out of the way) I saw his sats get to the 30s. They called a code well before then and the anaesthesiologist was already in intubating him.

I dont know the outcome of his case. This was a while ago and I think of it sometimes and don't know what could have been done differently. I also do not know if they debriefed or not as the house sup sent me to another 1:1

I can imagine that when patients get aggressive saying they cannot breathe, they are getting aggressive because they are desperate to breathe and are panicking.

I don't work with critically ill populations often. What is one supposed to do for said patients? What could we have done differently?