Stages of general anesthesia

Stages of general anesthesia

A. Stage I (induction) begins with the administration of intravenous agents or with inhalation of a

combination of anesthetic gases and oxygen

Endotracheal intubation is performed or newer devices are used ie. laryngeal mask airway,

esophageal tracheal combitube, or lighted stylet or wand to see vocal cords

B. Stage 2 (maintenance) during this phase the client is positioned, skin prepped, surgery performed

1. once it is safe for any of these activities to begin, then maintenance phase is begun

2. during this phase the appropriate levels of anesthesia are maintained. The depth of anesthesia

can be increased as needed

C. Stage III (emergence phase) this period begins when the anesthesiologist dereases the anesthetic

agents & pt begins to awaken

1. extubation usually occurs during this period

2. complications can occur such as laryngospasm, vomiting, slow spontaneous respirations, &

uncontrolled reflex movement

IV. Factors which place the intraoperative pt at risk;

A. advanced age can decrease tolerance of general anesthesia, physiologic changes in aging can

affect blood, fluid loss & replacement, hypothermia, pain, tolerance of surgical

procedure / position

B. respiratory disorders: respiration depression from general anesthesia & acid / base imbalances

can occur

C. renal & liver dysfunction: may poorly tolerate general anesthesia & can have fluid / electrolye

& acid / base imbalances, decreased metabolism & excretion of drugs

D. alcoholism can increase the amount of anesthesia required

E. medications: anticoagulants (including aspirin) can cause intraoperative hemorrhage

1. diuretics – esp. thiazides can cause fluid & electrolyte imbalances. some are K⁺ sparing,

some are not. can produce altered cardio / vasc response & respiratory depression

2. antihypertensives (esp. phenothiazines) can increase hypotensive affects of anesthesia

3. antidepressants (esp. monoamine oxidase inhibitors) can increase hypotensive affects

4. antibiotics (esp. "mycin") may cause apnea and resp. paralysis

5. herbal supplements – can prolong anesthesia affects. esp. ones with sedative affects,

ie. St. John's wort (can increase bleeding risk, increase BP)

V. Potential Intraoperative Complications

A. Nausea & vomiting: if gagging occurs, turn pt to side & head of bed lowered to prevent aspiration

anesthesiologist can give antiemetics

B. hypoxia & respiratory complications: inadequate ventilation, occlusion of airway, inadvertently

put in esophagus instead of trachea

peripheral perfusion is checked frequently and oxygen sat monitored

C. Hypothermia: body temp below normal 98.0

1. glucose if metabolism is reduced. as a result can have metabolic acidosis?

2. warm solutions can be given, blankets, change any wet gowns, remove wet drapes

read pg 63 about malignant hypertension box 4-1