I have used a bath cloth around the wrist then a ziptie over it........when it's tightened down it pulls into the cloth but does'nt leave a mark on the wrists.

Another ziptie ran through the first one makes for a loop to attach a snap to......the snap is attached to a peice of rope,one for each corner of the bed.

Works the same on the ankles too........or for that matter loop a longer one around the bend of the knee.

Works great for spread eagle,face up or face down.

Never had an escapee yet.