Facts on File Encyclopedia of Health and Medicine

full consciousness returns. Surgeons often use
conscious sedation to improve a person’s comfort
and reduce anxiety during minor operations, usu-
ally in combination with local or regional anesthe-
sia. Usually an anesthesiologist or anesthetist
administers the sedative medication intravenously
with ongoing monitoring of the person’s response
to the medication, level of awareness, and vital
signs such as BREATHINGrate,HEART RATE, and blood
pressure.
Rarely, a person may experience NAUSEA or
headache after conscious sedation. More rarely, a
person may have distressing memories of the
operation. Though a person appears to return to
normal consciousness quickly, the medication may
remain at a level in the blood circulation that
affects perception and function for 24 hours after
its administration. Doctors caution people to avoid
driving or performing activities that require alert-
ness and coordination for at least 24 hours after
conscious sedation.

POTENTIAL DRUG INTERACTIONS WITH ANESTHESIA

Many prescription medications, OVER-THE-

COUNTER (OTC) DRUGS, NUTRITIONAL SUPPLEMENTS,

and MEDICINAL HERBS AND BOTANICALScan interfere

with anesthesia or BLOODclotting. It is important

to tell the surgeon of all such medications and

products. The surgeon or the anesthesiologist

may request the person to stop taking certain

drugs or herbs for a period of time before and

sometimes also after surgery.

General Anesthesia
General anesthesia establishes a state of deep
UNCONSCIOUSNESSin which the anesthetic agents
circulate in the body to block pain signals, prevent
movement, and block memory of the operation.
The anesthetic agents may be gases the person
inhales or medications (such as sedatives, hyp-
notics, and MUSCLErelaxants) the anesthetist or
anesthesiologist injects intravenously. An endotra-
cheal tube inserted through the MOUTH, into the
THROAT, and to the top of the trachea allows the
anesthesiologist to seal the airway to prevent for-
eign matter from entering the LUNGS, as the anes-
thetic suppresses the COUGH REFLEX that would
normally keep mucus and debris from entering
the trachea. The endotracheal tube also ensures

that oxygen and anesthetic gases directly enter the

lungs. General anesthesia is the standard for oper-

ations on the upper abdomen and chest as well as

for many major orthopedic operations. In some

circumstances the anesthesiologist may combine

epidural or spinal anesthesia with general anes-

thesia. Many general anesthesia agents are fast

acting and short lived, allowing rapid anesthetic

induction as well as quick recovery.

COMMON GENERAL ANESTHETIC AGENTS

Inhaled

enflurane halothane isoflurane

methoxyflurane nitrous oxide

Injected

etomidate KETAMINE methohexital

propofol thiopental

Sophisticated equipment allows precise and

safe administration of inhaled anesthetics, includ-

ing ongoing adjustments of carbon dioxide and

oxygen concentrations. The anesthesiologist or

anesthetist continuously monitors the person’s

vital signs, including breathing rate, oxygen satu-

ration, heart rate, blood pressure, and body tem-

perature. The most common side effects of general

anesthesia are nausea, VOMITING, a slow return to

normal bowel activity, and a prolonged sense of

grogginess. The anesthesiologist or anesthetist can

administer medications to ease or relieve these

symptoms. Sore throat is a common complaint

after general anesthesia, a consequence of the

endotracheal tube.

Though most general anesthetic agents do not

persist in the body at functional levels beyond 24

to 36 hours, many people feel they are not quite

themselves for several days after general anesthe-

sia. Postoperative analgesic medications can exac-

erbate this perception. Walking, to the extent

possible, and stool softeners help BOWEL MOVEMENT

return to normal. Allergic reaction to anesthetic

agents is uncommon but occurs, so it is important

to tell both the surgeon and the anesthesiologist

or anesthetist of any allergies, including to foods.

Smoking, certain prescription medications, ILLICIT

DRUG USE, and ALCOHOL consumption affect the

ways in which various anesthetic agents function

in the body.

262 Surgery