Drug Study: Types of Anesthesia

Anesthesia, or anaesthesia has traditionally meant the condition of having sensation (including the feeling of pain) blocked. This allows patients to undergo surgery and other procedures without the distress and pain they would otherwise experience. The word was coined by Oliver Wendell Holmes, Sr. in 1846. Another definition is a “reversible lack of awareness”, whether this is a total lack of awareness (e.g. a general anaesthestic) or a lack of awareness of a part of a the body such as a spinal anaesthetic or another nerve block would cause. Anesthesia differs from analgesia in blocking all sensation, not only pain.

Classification:

A. General Anesthesia - is the loss of all sensation and consciousness. Protective reflexes such as cough and gag reflexes are lost. A general anesthetic acts by blocking awareness centers in the brain so that amnesia (loss of memory), analgesia (insensibility to pain), hypnosis (artificial sleep), and relaxation (rendering a part of the body less tense) occur. General anesthetics are usually administered by intravenous infusion or by inhalation of gases through a mask or through an endotracheal tube inserted into the trachea.

Advantages:

• Because the client is unconscious rather then awake and anxious, respiration and cardiac function are readily regulated.
• The anesthesia can be adjusted to the length of the operation and the client’s age and physical status.

Disadvantage:

• It depresses the respiratory and circulatory systems.
• Some clients become more anxious about a general anesthetic that about the surgery itself. Often this is because they fear losing the capacity to control their own bodies.
  

B. Regional Anesthesia - is the temporary interruption of the transmission of nerve impulses to and from a specific area or region of the body. The client loss sensation in an area of the body but remains conscious. Several techniques are used:
1. Topical (surface) Anesthesia

• Is applied directly to the skin and mucous membranes, open skin surfaces, wounds, and burns. The most common used topical agents are lidocaine (Xylocaine) and benzocaine. Topical anesthetics are readily absorbed and act rapidly.

2. Local Anesthesia

• (Infiltration)is injected into a specific area and is used for minor surgical procedures such as suturing a small wound or performng a biopsy. Lidocaine or tetracaine 0.1% may be used.

3. Nerve Block

• Is a technique in which the anesthetic agent is injected into and around a nerve or small nerve group that supplies sensation to a small area of the body. Major blocks involve multiple nerves or a plexus (e.g. the brachial plexus anesthetizes the arm); minor blocks involve a single nerve (e.g. a facial nerve)

4. Intravenous block (Bier block)

• Is used most often for procedures involving the arm, wrist and hand. An occlusion tourniquet is applied to the extremity to prevent infiltration and absorption of the injected intravenous agent beyond the involved extremity.

5. Spinal anesthesia (Subarachnoid block)

• It requires a lumbar puncture through one of the interspaces between lumbar disc 2 (L2) and the sacrum (S1). An anesthetic agent is injected into the subarachnoid space surrounding the spinal cord. Categorized into Low Spinals (saddle or caudal blocks) are primarily used for surgeries involving the perineal or rectal areas. Mild Spinals (below the level of the umbilicus - T10) can be used for hernia repairs or appendectomies. High Spinals (reaching the nipple line - T4) can be used for surgeries such as cesarean sections.

6. Epidural (peridural) anesthesia

• Is an injection of an anesthetic agent into the epidural space, the area inside the spinal column but outside the dura mater.
  Conscious Sedation may be used alone or in conjuction with regional anesthesia for some diagnostic tests and surgical procedures. Conscious sedation refers to minimal depression of the level of consciousness in which the client retains the ability to maintain a patent airway and respond appropriately to commands.

Intravenous narcotics such as morphine or fentanyl (Sublimaze) and antianxiety agents such as diazepam (Valium) or midazolam (Versed) are commonly used to induce and maintain conscious sedation. Conscious sedation increases the client’s pain threshold and induces a degree of amnesia but allows for prompt reversal of its effects and a rapid return to normal activities of daily living. Procedures such as endoscopies, incision and drainage of abcesses, and even balloon angioplasty may be performed under conscious sedation.

Risk Factors for Complications During the Procedure:

• Current or past health problems
• Taking medications, supplements, or herbal remedies, blood thinners
• Allergies (eg, food allergies, medication allergies, latex allergies)
• Smoking
• Drinking alcohol
• Taking recreational drugs
• Personal or family history of adverse reactions to anesthesia

Possible Complications:

• Pain and tenderness around the injection site
• Bruising, infection, or bleeding of the injection site
• Hematoma (a mass of clotted blood that forms in a tissue, organ, or body space as a result of a broken blood vessel)
• Spinal headache (a severe headache that may occur after spinal or epidural anesthesia)
• Decrease in blood pressure
• Nerve damage
• Medication mistakenly injected into a vein; symptoms include dizziness, rapid heartbeat, and funny taste or numbness around the mouth
• Horner’s syndrome (change of pupil size on one side)
• Ptosis (drooping of the eyelid)
• Pneumothorax (air trapped between the lung and rib cage)

Call Your Doctor If Any of the Following Occurs:

• Signs of infection, including fever and chills
• Redness, swelling, increasing pain, or discharge from the injection site
• Tingling, numbness, or trouble moving around the affected area
• Headache
• Persistent coughing
• Chest pain
• Trouble breathing or shortness of breath
• Dizziness
• Heartbeat abnormalities
• Funny taste or numbness of the mouth
• Other worrisome symptoms
  

Resources:

• http://en.wikipedia.org/
• http://www.thompsonhealth.com/
• Fundamentals of Nursing - Barbara Kozier et al