Figure 5-3.Stages of anesthesia.
GENERAL ANESTHESIA. General anesthetics cause total loss of sensation and complete loss of consciousness in the patient. They are administered by inhalation of certain gases or vaporized liquids, intravenous infusion, or rectal induction. The induction of inhalation anesthesia is divided into four stages. These stages and the bodys main physiological reaction in each phase are explained below and depicted in figure 5-3.
Stage 1 is called the stage of analgesia or induction. During this period, the patient experiences dizziness, a sense of unreality, and a lessening sensitivity to touch and pain. At this stage, the patients sense of hearing is increased and responses to noises are intensified (fig. 5-3).
Stage 2 is the stage of excitement. During this period, there is a variety of reactions involving muscular activity and delirium. At this stage, the vital signs show evidence of physiological stimulation. It is important to remember that during this stage the patient may respond violently to very little stimulation (fig. 5-3).
Stage 3 is called the surgical or operative stage. There are four planes to this stage.