Cardiopulmonary resuscitation (CPR) was an emergency medical procedure that could be used on victims of cardiac arrest.
When Aeryn Sun was going to use the kill shot on John Crichton, he did not trust it and taught her CPR. While doing so, he told her that he had four minutes (180 microts) before he would die. After administering the kill shot, Aeryn began her work, but was not able to finish in the allotted, and headed back to Crichton with the nerve shot to wake him up. On the way, she was knocked out and woke to discover the vial smashed. She used the CPR she had learned to resuscitate Crichton. ("The Flax")