Sedation and Anesthesia - Surgical Experience

The Surgical Experience

During the surgical procedure, the patient will need sedation, anesthesia, or a combination of these.

SEDATION AND ANESTHESIA

Sedation and anesthesia have four levels: minimal sedation, mod-erate sedation, deep sedation, and anesthesia. Standards of care for each level have been set by JCAHO. A surgical procedure may also be performed using anesthetic agents that suspend sensation in parts of the body (local, regional, epidural, or spinal anesthesia).

For the patient, the anesthesia experience consists of having an intravenous line inserted, if it was not inserted earlier; receiving a sedating agent prior to induction with an anesthetic agent; losing consciousness; being intubated, if indicated; and then receiving a combination of anesthetic agents. Typically the experience is a smooth one and the patient has no recall of the events.

Minimal Sedation

The minimal sedation level is a drug-induced state during which the patient can respond normally to verbal commands. Cognitive function and coordination may be impaired, but ventilatory and cardiovascular functions are not affected (JCAHO, 2001; Patter-son, 2000a, b).

Moderate Sedation

Moderate sedation is a form of anesthesia that may be producedintravenously. It is defined as a depressed level of consciousness that does not impair the patient’s ability to maintain a patent air-way and to respond appropriately to physical stimulation and ver-bal command. Its goal is a calm, tranquil, amnesic patient who, when sedation is combined with analgesic agents, is relatively pain-free during the procedure but able to maintain protective re-flexes (JCAHO, 2001; Patterson, 2000a, b). Sedation can be ad-ministered by an anesthesiologist, anesthetist, other physician, or nurse. When administered by an anesthesiologist or anesthetist, moderate sedation is referred to as monitored anesthesia care. The medications permitted for use in moderate sedation vary with the credentials of the person administering the sedative. In addition, state departments of health are very specific about who may ad-minister moderate sedation and about the training required for those individuals. These regulations vary greatly from state to state.

Midazolam (Versed) or diazepam (Valium) is used frequently for intravenous sedation. In some states, the physician must ad-minister the first dose; a nurse with special training can admin-ister subsequent doses. Other medications used include analgesic agents (eg, morphine, fentanyl) and reversal agonists, such as naloxone (Narcan). A nurse who is knowledgeable and skilled in detecting dysrhythmias, administering oxygen, and performing resuscitation must continuously monitor the patient who re-ceives sedation. The patient receiving this form of anesthesia is never left alone and is closely monitored for respiratory, cardio-vascular, and central nervous system depression using such methods as pulse oximetry, ECG, and frequent measurement of vital signs (Patterson, 2000a, b). The level of sedation is moni-tored by the patient’s ability to maintain a patent airway and to respond to verbal commands.

Moderate sedation may be used alone or in combination with local, regional, or spinal anesthesia. Its use is increasing as more surgical procedures and diagnostic studies are performed in ambulatory and same-day settings with the expectation that the pa-tient will be discharged home a few hours after the procedure.

Deep Sedation

Deep sedation is a drug-induced state during which a patient can-not be easily aroused but can respond purposefully after repeated stimulation (JCAHO, 2001). The difference between deep seda-tion and anesthesia is that the anesthetized patient is not arousable. Deep sedation and anesthesia are achieved when an anesthetic agent is inhaled or administered intravenously. Inhaled anesthetic agents include volatile liquid agents and gases (Aranda & Hanson, 2000; Townsend, 2002). Volatile liquid anesthetics produce anes-thesia when their vapors are inhaled. Included in this group are halothane (Fluothane), enflurane (Ethrane), isoflurane (Forane), sevoflurane (Ultrane), and desflurane (Suprane). All are adminis-tered with oxygen, and usually with nitrous oxide as well.

Gas anesthetics are administered by inhalation and are always combined with oxygen. Nitrous oxide is the most commonly used gas anesthetic. When inhaled, the anesthetics enter the blood through the pulmonary capillaries and act on cerebral centers to produce loss of consciousness and sensation. When anesthetic ad-ministration is discontinued, the vapor or gas is eliminated through the lungs. Table 19-1 lists the advantages, disadvantages, and im-plications of the different volatile liquid and gas anesthetics.

Anesthesia

General anesthesia consists of four stages, each associated with specific clinical manifestations. When opioid agents (narcotics) and neuromuscular blockers (relaxants) are administered, several of the stages are absent. The anesthesia level consists of general anesthesia and spinal or major regional anesthesia but does not include local anesthesia ( JCAHO, 2001). Anesthesia is a state of narcosis (severe central nervous system depression produced by pharmacologic agents), analgesia, relaxation, and reflex loss. Pa-tients under general anesthesia are not arousable, even to painful stimuli. They lose the ability to maintain ventilatory function and require assistance in maintaining a patent airway. Cardiovascular function may be impaired as well (JCAHO, 2001).

STAGE I: BEGINNING ANESTHESIA

As the patient breathes in the anesthetic mixture, warmth, dizzi-ness, and a feeling of detachment may be experienced. The patient may have a ringing, roaring, or buzzing in the ears and, though still conscious, may sense an inability to move the extremities easily. During this stage, noises are exaggerated; even low voices or minor sounds seem loud and unreal. For this reason, the nurse avoids making unnecessary noises or motions when anesthesia begins.

STAGE II: EXCITEMENT

The excitement stage, characterized variously by struggling, shouting, talking, singing, laughing, or crying, is often avoided if the anesthetic is administered smoothly and quickly. The pupils dilate, but contract if exposed to light; the pulse rate is rapid, and respirations may be irregular.

Because of the possibility of uncontrolled movements of the patient during this stage, the anesthesiologist or anesthetist must always be assisted by someone ready to help restrain the patient. A strap may be in place across the patient’s thighs, and the hands may be secured to an armboard. The patient should not be touched except for purposes of restraint, but restraints should not be ap-plied over the operative site. Manipulation increases circulation to the operative site and thereby increases the potential for bleeding.

STAGE III: SURGICAL ANESTHESIA

Surgical anesthesia is reached by continued administration of the anesthetic vapor or gas. The patient is unconscious and lies quietly on the table. The pupils are small but contract when ex-posed to light. Respirations are regular, the pulse rate and volume are normal, and the skin is pink or slightly flushed. With proper administration of the anesthetic, this stage may be maintained for hours in one of several planes, ranging from light (1) to deep (4), depending on the depth of anesthesia needed.

STAGE IV: MEDULLARY DEPRESSION

This stage is reached when too much anesthesia has been admin-istered. Respirations become shallow, the pulse is weak and thready, and the pupils become widely dilated and no longer con-tract when exposed to light. Cyanosis develops and, without prompt intervention, death rapidly follows. If this stage devel-ops, the anesthetic is discontinued immediately and respiratory and circulatory support is initiated to prevent death. Stimulants,although rarely used, may be administered; narcotic antagonists can be used if overdosage is due to opioids.

During smooth administration of an anesthetic, there is no sharp division between the first three stages, and there is no stage IV. The patient passes gradually from one stage to another, and it is only by close observation of the signs exhibited by the patient that an anesthesiologist or anesthetist can control the situation. The re-sponses of the pupils, the blood pressure, and the respiratory and cardiac rates are probably the most reliable guides to the patient’s condition.