Anesthesia, Local Health Article

Topical anesthetics

Unless advised by a doctor, topical anesthetics should not be used on or near any part of the body with large sores, broken or scraped skin, severe injury, or infection. They should also not be used on large areas of skin. Some topical anesthetics contain alcohol and should not be used near an open flame or while smoking.

Patients should be careful not to get topical anesthetics in the eyes, nose, or mouth. If a spray-type anesthetic is to be used on the face, it can be applied with a cotton swab or sterile gauze pad. After using a topical anesthetic on a child, the caregiver should make sure the child does not get the medicine in his or her mouth or eyes.

Topical anesthetics are intended for the temporary relief of pain and itching. They should not be used for more than a few days at a time. A doctor should be consulted if:

• Discomfort continues for more than seven days.
• The problem gets worse.
• The treated area becomes infected.
• New signs of irritation such as skin rash, burning, stinging, or swelling appear.

Dental anesthetics

Dental anesthetics should not be used if certain kinds of infections are present. Package directions should be checked or a dentist, pharmacist, or doctor should be consulted if there is any uncertainty. Dental anesthetics should be used only for temporary pain relief. Consult the dentist if problems such as toothache, mouth sores, or pain from dentures or braces continue or if signs of general illness such as fever, rash, or vomiting develop.

Patients should not eat or chew gum while the mouth is numb from a dental anesthetic to avoid accidentally biting the tongue or the inside of the mouth. In addition, nothing should be eaten or drunk for one hour after applying a dental anesthetic to the back of the mouth or throat, because the medicine may interfere with swallowing and may cause choking. If normal feeling does not return to the mouth within a few hours after receiving a dental anesthetic or if it is difficult to open the mouth, the dentist should be consulted.

Ophthalmic anesthetics

When anesthetics are used in the eye, it is important not to rub or wipe the eye until the effect of the anesthetic has worn off and feeling has returned. Rubbing the eye while it is numb could cause injury.

Description

Medical procedures and situations that regularly make use of local or regional anesthesia include the following:

• biopsies, in which skin or tissue samples are taken for diagnostic procedures
• childbirth
• scar repair
• surgery on the face (including plastic surgery), skin, arms, hands, legs, and feet
• eye surgery
• surgery involving the urinary tract or reproductive organs

Surgery involving the chest or abdomen is usually performed under general anesthesia. Laparoscopy and hernia repair, however, may be performed under local or regional anesthesia.

Local and regional anesthesia have many advantages over general anesthesia. Most importantly, the risk of unusual and sometimes fatal reactions to general anesthesia is lessened. More minor, but significant, risks of general anesthesia include longer recovery time and the psychological discomfort of losing consciousness.

Regional anesthesia typically affects a larger area than local anesthesia. As a result, regional anesthesia is typically used for more involved or complicated procedures. The duration of action of an anesthetic depends on the type and amount of anesthetic administered.

Regional anesthetics are injected. Local anesthesia involves the injection into the skin or application to the skin surface of an anesthetic directly where pain will occur. Local anesthesia can be divided into four groups: injectable, topical, dental (non-injectable), and regional blockade injection.

Local and regional anesthesia work by altering the flow of sodium molecules into nerve cells (neurons) through the cell membrane. The exact mechanism is not understood, since the drug apparently does not bind to any receptor on the cell surface and does not seem to affect the release of chemicals that transmit nerve impulses (neurotransmitters) from the nerve cells. Experts believe, however, that when the sodium molecules do not get into the neurons, nerve impulses are not generated and pain impulses are not transmitted to the brain.