2. Intraoperative preparation - anesthesia: blocks transmission of nerve impulses, suppresses reflexes, promotes muscle relaxation, and in some instances achieves reversible unconsciousness.
   1. Intravenous conscious sedation - produces sedation and amnesia in ambulatory procedures, short surgical or diagnostic procedures. Allays fear and anxiety, elevates pain threshold, maintains consciousness and protective reflexes, and returns patient quickly to normal activities. Commonly used agents are benzodiazepines (midazolam, diazepam) and narcotics (fentanyl, meperidine, morphine).
   2. Regional anesthesia - purpose is to block pain reception and transmission in a specified area. Commonly used drugs are lidocaine HCI, tetracaine HCI, cocaine HCI, and procaine HCI. Types of regional anesthetics:
      1. Topical - applied to mucous membranes or skin; drug anesthetizes the nerves immediately below the area. May be used for bronchoscopic or laryngoscopic examinations. Side effects: rare anaphylaxis.
      2. Local infiltration - used for minor procedures; anesthetic drug is injected directly into the area to be incised, manipulated, or sutured. Side effects: rare anaphylaxis.
      3. Peripheral nerve block - regional anesthesia is achieved by injecting drug into or around a nerve after it passes from vertebral column; procedure is named for nerve involved, such as brachial-plexus block. Requires a high degree of anatomical knowledge. Side effects: may be absorbed into bloodstream. Observe for signs of excitability, twitching, changes in vital signs, or respiratory difficulties.
      4. Field block - a group of nerves is injected with anesthetic as the nerves branch from a major or main nerve trunk. May be used for dental procedures, plastic surgery. Side effects: rare.
      5. Epidural anesthesia - anesthetizing drug is injected into the epidural space of vertebral canal; produces a bandlike anesthesia around body. Frequently used in obstetrics. Rare complications. Slower onset than spinal anesthesia, not dependent on patient position for level of anesthesia, no postoperative headaches.
      6. Spinal anesthesia - anesthetizing drug is injected into the subarachnoid space and mixes with spinal fluid; drug acts on the nerves as they emerge from the spinal cord, thereby inhibiting conduction in the autonomic, sensory, and motor systems.
         1. Advantages: rapid onset; produces excellent muscle relaxation.
         2. Utilization: surgery on lower limbs, inguinal region, perineum, and lower abdomen.
         3. Disadvantages:
            1. Loss of sensation below point of injection for 2-8 hours - watch for signs of bladder distention; prevent injuries by maintaining alignment, keeping bedclothes straightened.
            2. Patient awake during surgical procedure - avoid light or upsetting conversations.
            3. Leakage of spinal fluid from puncture site - keep flat in bed for 24-48 hours to prevent headache. Keep well hydrated to aid in spinal-fluid replacement.
            4. Depression of vasomotor responses - frequent checks of vital signs.
      7. Intravenous regional anesthesia - used in an extremity whose circulation has been interrupted by a tourniquet; the anesthetic is injected into vein, and blockage is presumed to be achieved from extravascular leakage of anesthetic near a major nerve trunk. Precautions as for peripheral nerve block.
   3. General anesthesia - a reversible state in which the patient loses consciousness due to the inhibition of neuronal impulses in the brain by a variety of chemical agents; may be given intravenously, by inhalation, or rectally.
      1. Side effects:
         1. Respiratory depression.
         2. Nausea, vomiting.
         3. Excitement.
         4. Restlessness.
         5. Laryngospasm.
         6. Hypotension.
      2. Nursing care plan/implementation - Goal: prevent hazardous drug interactions.
         1. Notify anesthesiologist if patient is taking any of the following drugs:
            1. Antidepressants, such as Prozac - long half-life; monitor renal and liver function.
            2. Antihypertensives, such as reserpine, hydralazine, and methyldopa - potentiate the hypotensive effects of anesthetic agents.
            3. Anticoagulants, such as heparin, warfarin (Coumadin) - increase bleeding times, which may result in excessive blood loss or hemorrhage.
            4. Aspirin and NSAIDs - decrease platelet aggregation and may result in increased bleeding.
            5. Steroids, such as cortisone - anti-inflammatory effect may delay wound healing.
         2. Stages o f inhalation anesthesia and nursing goals:
         1. Stage I - extends from beginning of induction to loss of consciousness. Nursing goal: reduce external stimuli, because all movement and noises are exaggerated for the patient and can be highly distressing.
         2. Stage II - extends from loss of consciousness to relaxation; stage of delirium and excitement. Nursing goal: prevent injury by assisting anesthesiologist to restrain patient if necessary; maintain a quiet, nonstimulating environment.
         3. Stage III - extends from loss of lid reflex to cessation of voluntary respirations. Nursing goal: reduce risk of untoward effects by preparing the operative site, assisting with procedures, and observing for signs of complications.
         4. Stage IV - indicates overdose and consists of respiratory arrest and vasomotor collapse due to medullary paralysis. Nursing goal: promote restoration of ventilation and vasomotor tone by assisting with cardiac arrest procedures and by administering cardiac stimulants or narcotic antagonists as ordered.
   4. Intravenous agents - rapid and pleasant induction of anesthesia. Three categories: barbiturates (thiopental), narcotics, and neuromuscular blocking agents (succinylcholine, curare, pancuronium). Ketamine also used - may produce emergence delirium. IV drugs require liver metabolism and renal excretion.
   5. Hypothermia - a specialized procedure in which the patient’s body temperature is lowered to 28°-30°C (82°-86°F).
   1. Reduces tissue metabolism and oxygen requirements.
   2. Used in heart surgery, brain surgery, and surgery on major blood vessels.
   3. Nursing care plan/implementation:
      1. Goal: prevent complications:
         1. Monitor vital signs for shock.
         2. Note level of consciousness.
         3. Record intake and output accurately.
         4. Maintain good body alignment; reposition to prevent edema, pressure, or discoloration of skin.
         5. Maintain patent IV.
      2. Goal: promote comfort.
      1. Apply blankets to rewarm and prevent shivering.
      2. Mouth care.
      3. Goal: observe for indications of malignant hyperthermia - common during induction; may occur 24-72 hours postoperatively. Genetic defect of muscle metabolism; early sign is unexplained ventricular dysrhythmia, tachypnea, cyanosis, skin mottling; elevated temperature is not reliable indicator.
      1. Administer 100% O₂.
      2. Cool with ice packs or cooling blankets.
      3. Give dantrolene (muscle relaxant) per order.
   6. Evaluation/outcome criteria: complete reversal of anesthetic effects (e.g., spontaneous respirations, pupils react to light). No indication of intraoperative complications - cardiac arrest, laryngospasm, aspiration, hypotension, malignant hyperthermia.