Anesthesia, General Health Article

Aftercare

The anesthetist and medical personnel provide supplemental oxygen and monitor patients for vital signs and monitor their airways. Vital signs include an EKG (unless the patient is hooked to a monitor), blood pressure, pulse rate, oxygen saturation, respiratory rate, and temperature. The staff also monitors the patient's level of consciousness as well as signs of excess bleeding from the incision.

Complications

Although the risk of serious complications from general anesthesia are low, they can include heart attack, stroke, brain damage, and death. The risk of complications depends in part on the patient's age, sex, weight, allergies, general health, and history of smoking, drinking alcohol, or drug use.

The overall risk of mortality from general anesthesia is difficult to evaluate as of 2001, because so many different factors are involved, ranging from the patient's overall health and the circumstances preceding surgery to the type of procedure and the skill of the physicians involved. The risk appears to be somewhere between 1:1,000 and 1:100,000, with infants younger than age one and patients older than 70 being at greater risk.

Awareness during surgery

One possible complication is the patient's "waking up" during the operation. It is estimated that about 30,000 patients per year in the United States "come to" during surgery. This development is in part the result of the widespread use of short-acting general anesthetics combined with blanket use of neuromuscular blockade. The patients are paralyzed with regard to motion, but otherwise "awake and aware." At present, special devices that measure brain wave activity are used to monitor the patient's state of consciousness. The bispectral index monitor was approved by the FDA in 1996 and the patient state analyzer in 1999.

Nausea and vomiting

Post-operative nausea and vomiting is a common problem during recovery from general anesthesia. In addition, patients may feel drowsy, weak, or tired for several days after the operation, a combination of symptoms sometimes called the "hangover effect." Fuzzy thinking, blurred vision, and coordination problems are also possible. For these reasons, anyone who has had general anesthesia should not drive, operate machinery, or perform other activities that could endanger themselves or others for at least 24 hours, or longer if necessary.

Anesthetic toxicity

Inhalation anesthetics are sometimes toxic to the liver, the kidney, or to blood cells. Halothane may cause hepatic necrosis or hepatitis. Sevoflurane may react with the carbon dioxide absorbents in anesthesia machines to form compound A, a haloalkene that is toxic to the kidneys. The danger to red blood cells comes from carbon monoxide formed by the breakdown products of inhalation anesthetics in the circuits of anesthesia machines.

Malignant hyperthermia

Malignant hyperthermia is a rare condition caused by an allergic response to a general anesthetic. The signs of malignant hyperthermia include rapid, irregular heartbeat; breathing problems; very high fever; and muscle tightness or spasms. These symptoms can occur following the administration of general anesthetics, especially halothane.

Results

General anesthesia is much safer today than it was in the past, thanks to faster-acting anesthetics; improved safety standards in the equipment used to deliver the drugs; and better devices to monitor breathing, heart rate, blood pressure, and brain activity during surgery. Unpleasantside effects are also less common, in part because of recent developments in equipment that reduce the problems of anesthetizing patients with "difficult" airways. These developments include the laryngeal mask airway and the McCoy laryngoscope, which has a hinged tip on its blade that allows a better view of the patient's larynx.

Health care team roles

Nurse anesthetists sometimes work with physician anesthesiologists in administering general anesthesia. Anesthesiologist assistants are other allied health professionals who assist anesthesiologists. Anesthesiologist assistants help in many areas, including preparation for the delivery of general anesthesia; performance of pretreatment assessments; administration of maintenance and supportive drugs; airway management; and assistance with transferring the patient to the recovery room.

KEY TERMS

Analgesia—Relief from pain.

Anticholinergics—Drugs that interfere with impulses from the parasympathetic nervous system. They may be given before general anesthesia to reduce airway secretions or the risk of bronchospasm.

Anxiolytics—Medications given to reduce anxiety; tranquilizers. Benzodiazepines are the anxiolytics most commonly used to premedicate patients before general anesthesia.

Balanced anesthesia—The use of a combination of inhalation and intravenous anesthetics, often with opioids for pain relief and neuromuscular blockers for muscle paralysis.

Clathrates—Substances in which a molecule from one compound fills a space within the crystal lattice of another compound. One theory of general anesthesia proposes that water molecules interact with anesthetic molecules to form clathrates that decrease receptor function.

Laryngoscope—An endoscope equipped for viewing a patient's larynx through the mouth.

Malignant hyperthermia—A type of allergic reaction (probably with a genetic basis) that can occur during general anesthesia in which the patient experiences a high fever, the muscles become rigid, and the heart rate and blood pressure fluctuate.

Volatile anesthetics—Another name for inhalation anesthetics.