Medical hypnosis and biofeedback are essentially the same treatment. The difference is that with biofeedback, the patient is hooked up to a monitor, usually one that wraps around the finger, with the other end attached to a computer. The patient can then see how the mind and body truly connect.
In trance, the more focused the mind, the more relaxed the body. This causes the breathing to slow and the heart rate, or pulse, to decrease. Blood pressure also decreases and the skin temperature increases.
Biofeedback computer programs help patients learn to relax; older programs allowed patients to actually watch their pulse, respiratory rate, and/or skin temperature change as they view the monitor.
Newer biofeedback programs involve something called heart rate variability, which is beyond the scope of this brief answer.
The technique used in medical hypnosis to guide a patient into trance, and the work done while a patient is in trance is the same as when a patient is hooked up to a biofeedback machine. Dr. Lazarus typically does not use biofeedback, as he finds that his results with medical hypnosis alone are excellent.