ANESTHESIA AND RELATED COMPLICATIONS

ANESTHESIA                     AND                     RELATED COMPLICATIONS

The goals of anesthesia are to provide analgesia, sedation and muscle relaxation, to control the autonomic nervous system.

The absence of sensation

Anesthesiologist or Certified Registered Nurse Anesthetist

Anesthetics are classified as general and local and regional

General anesthetics

depress the CNS, alleviate pain, and cause a loss of consciousness.

there is loss of consciousness and sensation, with skeletal muscle relaxation, possible impaired ventilation and cardiovascular function, and elimination of the somatic, autonomic, and endocrine responsiveness including coughing, gagging, vomiting, and sympathetic nervous system responsiveness.

General anesthetics may be administered by inhalation and intravenous routes.

Advantages of General Anesthesia

Once an adequate airway has been established, the depth and rate of respiration can be controlled and attempts are made to protect the pulmonary tree from aspiration (inhalation of foreign material such as saliva or gastric contents).

Medication dosage can be easily titrated. Muscle relaxation for intubation and retraction at the surgical site is easily achieved.

ROUTE OF GA

Intravenous Agents

Virtually, all general anesthetics begin with an IV induction agent.

When used during the initial period of anesthesia, these agents induce a pleasant sleep with a rapid onset of action, only a few minutes, which allows for an endotracheal tube to be placed and an inhalation agent to be started.

Total intravenous anesthesia (TIVA). Recent advances anesthesia

All in IV medications are administered intravenously in TIVA, thus anesthetics eliminating the need for inhalation agents

Inhalation Agents.

The inhalation agents used for general anesthesia may be volatile liquids (liquid at room temperature) or gases (gas at room temperature).

Volatile liquids are administered through a vaporizer after being mixed with oxygen as carrier gas. Thus gas mixture is then delivered to the patient via anesthesia apparatus/circuit. Inhalation           agents    are          most       commonly administered via an endotracheal tube placed into the trachea once the patient has been induced with an IV agent. The endotracheal tube permits control of ventilation and airway protection both for patency and to prevent aspiration.

Local anesthetics

block pain at the site of administration, allowing consciousness to be maintained.

is the loss of sensation without loss of consciousness

Local anesthesia may be induced topically or via infiltration, intracutaneously, or subcutaneously.

Regional anesthesia

is the loss of sensation to a region of the body without loss of consciousness when a specific nerve or group of nerves is blocked with the administration of local anesthetic (e.g. spinal, epidural, or peripheral nerve block).

Balanced anesthesia

a combination of drugs, is frequently used in general anesthesia

Balanced anesthesia minimizes cardiovascular problems, decreases the amount of general anesthetic needed, reduces possible postanesthetic nausea and vomiting, minimizes the disturbance of organ function, and increases recovery from anesthesia.

balanced anesthesia generally includes the following:

1.       A hypnotic given the night before;

2.       Premedication, such as narcotic analgesic or benzodiazepine (e.g. Midazolam [Versed] and an anticholinergic (e.g., atropine, robinul). given about 1 hour before surgery to decrease secretions.

3.       A short-acting barbiturate, such as thiopental sodium (Pentothal);

4.       An inhaled gas, such as nitrous oxide and oxygen;

5.       A muscle relaxant, e.g. Anectine (SuccinylCholine), Pavulon (Pancuronium Hydrobromide).

Classification of Anesthesia

Anesthesia can be classified according to the effect on the patient's sensorium and pain perception. Four levels of sedation and anesthesia are as follows:

1.       Minimal sedation- the patient responds normally

2.       Moderate sedation/analgesia (Conscious sedation)

airway and cardiovascular functions are maintained.

Moderate sedation/analgesia (Conscious sedation) is a drug induced depression of consciousness that retains the patient's ability to maintain her or his own airway and to respond appropriately to verbal commands, yet the patient achieves a level of emotional and physical acceptance of a painful procedure (e.g. colonoscopy)

For conscious sedation often a combination of anxiolytic (e.g. Midazolam (Versed) and opioid (e.g. Fentanyl) drugs are used to provide analgesia, relieve anxiety, and/or provide amnesia.

3.       At deep sedation/analgesia, the patient is not easily aroused

4.      

General Anesthesia Agents

Intravenous agents

Nursing interventions

Barbiturates

■       Thiopental (Pentothal)

■       Methohexit al (Brevital)

■       Usually have minimal postoperative effects because of extremely short effects (less than 5 minutes)

■       Repeated doses may cause "hangover effect"

■       Monitor patients for adverse cardiac effects, hypotension,

At anesthesia in which the patient requires assisted ventilation.