What do you think would have helped you at the time? If you have some sense, maybe let him know in case it happens again. I don't know if this is an option for you (not sure if it is with current T), but a couple times when I was panicking in my marriage counselor's office, I wanted to go hide in the bathroom for a bit, but he suggested the three of us walk outside. I'm not sure if it was the movement, the fresh air, or not sitting in a room staring at each other (maybe all three), but it helped me deal with the panic. Ex-T did relaxation exercises with me a couple times, but those were kinda long and took up 15-20 minutes of session, so I never really wanted to do them. I also stepped out to the bathroom for 5 minutes once and splashed some cold water on my face (I've read that can stimulate the vagus nerve and calm you down). Helped a bit. My instinct when panicking is to want to run and hide, so I tried to fight against that in future sessions.

With current T, leaving the room for a couple minutes helped one time. The other time I had a panic attack during session with him, I think just his commenting on the fact that I was shaking and asking if I was really that scared about what would happen in the room that day helped. Because then I didn't feel I had to hide it (which I often feel I do, which tends to just make it worse...). And it was like he understood how scared I was. The other day, I wasn't having a panic attack, but he showed me some breathing exercises to do for future ones. So maybe if I'm panicking again in there, I could ask him to talk me through those again. Just some thoughts!