I had an experience in the past where I tied someone to an ottoman..... On her back, hands reaching backwards towards one end, legs spread, knees bent back so her feet were on each side - tied towards the end where her head was. I anchored her collar under the ottoman and ran it to the other end and tied off the rope there, so her head was stuck upside down, hanging off the ottoman. Having the head hang down, unable to bring it up can cause some damage if left unchecked.... from pinched nerves or just long term irritation of the neck vertebrae and muscles, but I didn't find anything that said how long I could keep her like that. I had to wing it, but I did release her neck from that position after about 40 minutes, checking about every 10 and first, then every 5. Each time she said she was ok, but I didn't trust it so I let her head up and slid her down a little so that her head was resting. When the session was over I asked her how her neck was. She was fine, but I'm still uneasy. Does anyone have any experience with keeping someone's head like this. It had some real advantages for her and me. She said the DT was better for her (me too) cause she could get more in without gagging, and she said it made her feel completely helpless, and she couldn't see what I was doing at the other end. The experience made me nervous cause with all the nasty things I did to her I still wanted her healthy enough to come right back and play again. Hurt.... No Harm.. Hope I explained the scene well enough. I'm sure you'll ask if you need clarification.