Encyclopedia of Health and Medicine

262 Surgery
full consciousness returns. Surgeons often use
conscious sedation to improve a person’s comfort
and reduce anxiety during minor operations, usually
in combination with local or regional anesthesia.
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 BREATHING rate, 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 alertness
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 BOTANICALS can interfere
with anesthesia or BLOOD clotting. 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
UNCONSCIOUSNESS in 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, hypnotics,
and MUSCLE relaxants) the anesthetist or
anesthesiologist injects intravenously. An endotracheal
tube inserted through the MOUTH, into the
THROAT, and to the top of the trachea allows the
anesthesiologist to seal the airway to prevent foreign
matter from entering the LUNGS, as the anesthetic
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 operations
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 anesthesia.
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, including
ongoing adjustments of carbon dioxide and
oxygen concentrations. The anesthesiologist or
anesthetist continuously monitors the person’s
vital signs, including breathing rate, oxygen saturation,
heart rate, blood pressure, and body temperature.
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 anesthesia.
Postoperative analgesic medications can exacerbate
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.