(2) Routes of administration of a general anesthetic agent are rectal (which is
not used much in today's medical practices), intravenous infusion, and inhalation. No
single anesthetic meets the criteria for an ideal general anesthetic. To obtain optimal
effects and decrease likelihood of toxicity, administration of a general anesthetic requires
the use of one or more agents. Often an intravenous drug such as thiopental sodium
(Pentothal) is used for induction and then supplemented with other agents to produce
surgical anesthesia. Inhalation anesthesia is often used because it has the advantage of
rapid excretion and reversal of effects.
Characteristics of the ideal general anesthetic are:
It produces analgesia.
It produces complete loss of consciousness.
It provides a degree of muscle relaxation.
It dulls reflexes.
It is safe and has minimal side effects.
(4) General anesthesia is used for major head and neck surgery, intracranial
surgery, thoracic surgery, upper abdominal surgery, and surgery of the upper and lower
b. A regional or block anesthetic agent causes loss of sensation in a large region
of the body. The patient remains awake but loses sensation in the specific region
anesthetized. In some instances, reflexes are lost also. When an anesthetic agent is
injected near a nerve or nerve pathway, it is termed regional anesthesia.
(1) Regional anesthesia may be accomplished by nerve blocks, or subdural or
epidural blocks (see figure 8-3).
Figure 8-3. Sites for spinal anesthetics.