In 1977, Oklahoma became the first state to adopt lethal 
injection as a means of execution, though it would be five more years until Charles Brooks would become the first person executed by lethal injection in Texas on December 7, 1982. Today, all of the states that have the death penalty use this method.
The condemned person is usually bound to a gurney and a member of the execution team positions several heart monitors on his skin. Two needles (one is a back-up) are then inserted into usable veins, usually in the inmate's arms. Long tubes connect the needle through a hole in a cement block wall to several intravenous drips. The first is a harmless saline solution that is started immediately. Then, at the warden's signal, a curtain is raised exposing the inmate to the witnesses in an adjoining room. Then, the inmate is injected with sodium thiopental - an anesthetic, which puts the inmate to sleep. Next flows pavulon or pancuronium bromide, which paralyzes the entire muscle system and stops the inmate's breathing. Finally, the flow of potassium chloride stops the heart. Death results from anesthetic overdose and respiratory and cardiac arrest while the condemned person is unconscious. (Ecenbarger, 1994 and Weisberg, 1991)
Medical ethics discourage doctors from participating in executions. However, a doctor sometimes will certify the inmate is dead. This lack of medical participation can be problematic because often injections are performed by inexperienced technicians or orderlies. If a member of the execution team injects the drugs into a muscle instead of a vein, or if the needle becomes clogged, extreme pain can result. Many prisoners have damaged veins resulting from intravenous drug use and it is sometimes difficult to find a usable vein, resulting in long delays while the inmate remains strapped to the gurney. (Ecenbarger, 1994 and Weisberg, 1991)
Due to reservations about their products being used in executions, many drug manufacturers have stopped selling drugs for executions. Recent shortages of the drugs used in executions have led to many changes in lethal injection procedures. Some states now use only one drug (typically pentobarbital), some use midazolam as the anesthetic in a 3-drug cocktail, and some states have stopped executions altogether as they search for a suitable method.