From the PADI website at
http://www.padi.com/english/common/courses/rec/continue/rescue.asp
What do I need to start?
You can enroll in the Rescue Diver Course as a certified Open Water Diver and participate in the Rescue Diver knowledge development and rescue training sessions, in confined water only, while working on your Advanced Open Water Diver certification.
Minimum age: 15 years old (12 for PADI Junior Rescue Diver)
Successful completion of a sanctioned CPR program within the past 24 months. The Emergency First Response Primary Care (CPR) and Secondary Care (First Aid) courses meet these requirements.
What will I do?
Rescue Diver training will prepare you to prevent problems and, if necessary, manage dive emergencies. During the five open water sessions, you'll cover:
Self-rescue and diver stress
AED and emergency oxygen delivery systems
dive first aid
swimming and non-swimming rescue techniques
emergency management and equipment
panicked diver response
underwater problems
missing diver procedures
surfacing the unconscious diver
in-water rescue breathing protocols
egress (exits)
first aid procedures for pressure related accidents
dive accident scenarios
How long will it take?
Recommended Course Hours: 25
Minimum Open Water Training: five sessions over two days
What will I need?
PADI Rescue Diver Crew-Pak
PADI Rescue Diver Video on DVD