Anesthetics, sometimes also spelled "anaesthetics," are drugs used in surgical procedures to reduce or eliminate pain and shock in patients thereby reducing recovery times. According to the text "Basics of Anesthesia," an estimated 28 million people undergo surgery with anesthesia every year in the U.S., with approximately one in every 250,000 dying from anesthesia-related complications. There are different methods of anesthetizing patients, each of which carries its own side effects.
Side Effects from General Anesthesia
General anesthesia entails a loss of consciousness via injected and/or inhaled drugs, although the mode of action is not known. Nitrous oxide, isoflurane, desflurane and sevoflurane are the most common inhaled anesthetics. General anesthesia is usually reserved for invasive surgeries, and carries the most risk of complications because it affects the entire body. The most serious side effects are dramatic changes in blood pressure and heart rate, which can lead to heart attack, stroke and death, as cited by MayoClinic.com.
General anesthesia suppresses throat reflexes such as coughing, swallowing and gagging, but objects and liquids can still end up in the trachea or the lungs and lead to pulmonary aspiration and infection. Vomiting is a common cause of pulmonary aspiration, which is why patients are told not to eat or drink for many hours before surgery. Endotracheal tubes are inserted down the throat to prevent pulmonary aspiration, but the tubes themselves can injury the lips, teeth, mouth and larynx.
Some patients become conscious during general anesthesia and can feel the pain, although they remain paralyzed. This is termed intraoperative awareness, and it's estimated that about two per 1,000 patients who receive general anesthesia experience it, according to a 2008 article in the "Canadian Medical Association Journal."
Side Effects from Regional Anesthesia
Regional anesthesia infers an injection of drugs near the spinal cord, nerve roots or larger peripheral nerves such that a specific region of the body is numbed. Lidocaine, bupivacaine, ropivacaine and tetracaine are the most used local anesthetics. The most common side effect is nerve damage, which can lead to chronic pain, numbness and muscle weakness.
Regional anesthesia, such as nerve blocks, spinal blocks and epidurals for childbirth also carry risk for systemic toxicity, which occurs if too much of the injected anesthetic is absorbed into the body from the blood, and arachnoiditis of the spinal tissues, according to the Arachnoiditis Sufferers Action and
Monitoring Society of New Zealand. Other side effects include localized infection, swelling and bruising at the injection site.
Side Effects from Local Anesthesia
Local anesthesia involves injected drugs which numb a focal area, but leave the patient conscious. The most common local anesthetic is novocaine, which is frequently used by dentists. Local anesthetics carry the least risk of side effects, although systemic toxicity, focal infection and nerve damage is still possible. More common side effects include headaches, nausea and mental confusion.
Malignant Hyperthermia
Although rare, the potentially fatal condition called malignant hyperthermia may be caused by anesthetics, according to the Malignant Hyperthermia Association. Malignant hyperthermia is a dramatic increase in skeletal muscle oxidation, which produces too much carbon dioxide and affects body temperature regulation. The most common anesthetics that can trigger this condition are the inhalation anesthetics and the muscle relaxant, succinylcholine.
References
- "Basics of Anesthesia"; R. Stoelting & R. Miller; 2006
- MayoClinic.com: Anesthesia Risks
- "Canadian Medical Association Journal"; Awareness during Anesthesia; B. Orser et al; 178-2, 2008
- A.S.A.M. Society: Epidural Complications
- Malignant Hyperthermia Association: Dangerous Anesthetics
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