1. To keep the patient safe and to regulate anesthetic depth Anesthetic Monitoring

2.  Vital signs ◦ Homeostatic mechanism’s response to anesthesia ◦ Heart rate ◦ Heart rhythm ◦ Respiratory rate and depth ◦ Mucous membrane color ◦ Capillary refill time ◦ Pulse strength ◦ Blood pressure ◦ Body temperature  Best indicator of patient wellbeing

3.  Reflexes ◦ Involuntary response to stimulus ◦ Palpebral, corneal, pedal, swallowing, laryngeal, and papillary light reflexes ◦ Indicators of anesthetic depth  Parameters offer predictable responses to anesthesia at various depths  May be affected by drugs, disease, or individual response variation  Monitor anesthetized patients as often as possible; continuously is ideal

4.  Four stages (I, II, III, IV)  Stage III divided into four planes  From stage I through stage IV there is a progressive decrease in pain perception, motor coordination, consciousness, reflex responses, muscle tone, and cardiopulmonary function

5.  Period of voluntary movement  Patient begins to lose consciousness  Characterized by: ◦ Fear, excitement, disorientation, struggling, urination, defecation ◦ Increased heart rate and respiratory rate  Stage ends with loss of ability to stand and recumbency

6.  Period of involuntary movement; the “excitement stage”  Characterized by: ◦ Breathing irregular ◦ Vocalization, struggling, paddling ◦ Increased heart and respiratory rate, pupils dilated, muscle tone marked, reflexes present  Actions are not under conscious control  Stage ends with muscle relaxation, decreased respiratory rate, and decreased reflex activity

7.  Period of surgical anesthesia  Divided into four planes  Plane 1: not adequate for surgery: ◦ Regular respiratory pattern, no involuntary limb movements ◦ Eyeballs start to rotate ventrally, pupils partially constricted, decreased pupillary light reflex ◦ Endotracheal tube may be passed and connected to gas anesthetic machine ◦ Other reflexes are still present but decreased response

8.  Suitable depth for most surgical procedures  Characterized by: ◦ Regular and shallow respiration with decreased rate ◦ Blood pressure and heart rate mildly decreased ◦ Relaxed muscle tone ◦ Pedal and swallowing reflexes are absent ◦ Ventromedial eye rotation

9.  Surgical stimulation may produce: ◦ Mild increase in heart rate, blood pressure, or respiratory rate ◦ Patient remains unconscious and immobile ◦ Pupillary light response is sluggish; pupil size is moderate

10.  Deep anesthesia—excessive for most procedures  Characterized by: ◦ Low heart and respiratory rates, decreased tidal volume ◦ Reduced pulse strength ◦ Increased capillary refill time (CRT) ◦ Poor to absent papillary light reflex; central eyeballs; moderately dilated pupils ◦ Reflexes are totally absent; muscle tone is very relaxed

11.  Early anesthesia overdose  Characterized by: ◦ Abdominal breathing ◦ Fully dilated pupils; dry eyes ◦ All reflexes are absent ◦ Marked depression of the cardiovascular system, pale mucous membranes, increased CRT ◦ Flaccid muscle tone

12.  Period of anesthetic overdose  Characterized by: ◦ Cessation of respiration ◦ Circulatory collapse ◦ Death  Resuscitate immediately to save the patient

13.  Alternative classification  Plane 1: “light” surgical anesthesia ◦ Not suitable for surgery  Plane 2: “medium” surgical anesthesia ◦ Optimum depth for most surgical procedures  Plane 3: “deep” surgical anesthesia ◦ Excessive depth

14.  Patient doesn’t move  Patient isn’t aware  Patient doesn’t feel pain  Patient has no memory of the procedure