The descriptions offered below are meant only as guidelines.
Some tailoring will often be required to inform potential subjects
adequately of deviations from the descriptions. For some procedures,
alternative descriptions are offered.
ACTH Test
This test determines whether your adrenal gland is functioning
normally. A catheter (a thin, flexible plastic tube) will be
put into an arm vein. You will be asked to lie down and will
be given an injection into a different arm vein. Periodic blood
samples will be drawn from the catheter in your vein for the
next 3 hours. You will be able to move around during the test.
Discomforts and risks: As with any vein puncture, it
may be necessary to try more than once to insert the needle successfully,
and you may get a hematoma ("black-and-blue" mark or
lump). You may have some local pain at the needle site. There
is a very small risk of infection.
Apheresis, Manual and Automated
The purpose of these 2-hour procedures is to treat certain
conditions or to allow the investigator to obtain a larger number
of white blood cells, red blood cells, or platelets for study
than would be possible with usual blood-drawings. Similar procedures
are used daily in blood banks to obtain blood products from healthy
donors. Blood may be drawn on ____ occasions, but only
from arm veins.
In manual apheresis, blood is drawn through a needle in the
vein of one arm, into a plastic bag, and spun (centrifuged in
a machine) to separate red blood cells from other blood components.
The red blood cells are then returned to your body through the
same needle.
In automated apheresis, blood is removed through a needle
in the vein of one arm, continuously spun (centrifuged) in a
machine that separates the desired component (usually white blood
cells and plasma), and the remainder (mostly red blood cells)
is returned continuously to the donor through a needle in a vein
of the other arm (or through the same needle used to draw the
blood).
Arterial (Radial) Catheterization
A catheter (a thin, flexible plastic tube) is inserted in
one of the two arteries at your wrist. Before the catheter is
inserted, we will make sure that both arteries are working. A
small amount of a local anesthetic (numbing medicine) will be
injected to numb the skin over the artery. Then, the catheter
will be placed in the artery and fastened with tape. From this
catheter we will take ___ samples, of ___ teaspoons each.
Discomforts and risks: Some discomfort is connected
with placement of the arterial needle. Rarely, people faint.
Even more rarely, the catheter gets infected. There is a remote
chance that the artery might get blocked, but this has not been
observed in several thousand of these procedures at NIH. Bruising
or swelling at the site of the arterial catheter occurs in 5
percent to 20 percent of patients, but this is only temporary;
permanent damage is extremely rare. We will watch for these risks
and treat any problems that occur.
In the most extreme case, arterial blockage could cause loss
of a hand or arm in patients with pre-existing severe disease
of the artery. This complication has never been observed in individuals
with normal circulation, and we will exclude those with abnormal
circulation.
Biopsy, Liver
A needle is passed through the skin into the liver, beneath
the right side of the lower ribcage, to obtain a small piece
of tissue.
Discomforts and risks: About 20 percent of patients
have some local pain lasting from a few minutes to several hours;
this rarely requires medication and disappears within a day or
two. In less than 1 case in 1,000, the biopsied liver bleeds
severely, and blood transfusion or even surgery is needed; death
has occurred from bleeding in less than 1 case in 10,000.
Biopsy, Muscle
The procedure is performed in the operating room. After a
local anesthetic numbs the skin, an incision, 1/2 inch to 1 inch
long, is made in the thigh (or upper arm), and a small piece
of muscle is removed. The skin is closed with self-absorbing
stitches. If the biopsy is done on your thigh, you may be asked
to stay off your feet for 6 hours after the procedure.
Discomforts and risks: Discomfort during the procedure
will be avoided by the use of a local anesthetic. The biopsy
site may be tender for several days; this is usually controlled
by medication. Risks include the rare complications of local
bleeding or infection. A small scar will remain permanently at
the biopsy site.
Biopsy, Nerve
The procedure is performed in the operating room. After a
local anesthetic numbs the skin, an incision about 1 inch long
will be made, usually just below the outside of the ankle or
in mid-calf. A piece of nerve about 1 inch long will be removed.
The skin will be closed with self-absorbing stitches.
Discomforts and risks: The biopsy site may be sore
for a few days; this is usually controlled by aspirin-like pain
medication. An area of numbness along the outside half of the
heel, along the incision, or in the heel, occurs occasionally
and usually subsides after 2 or 3 weeks but can persist for more
than a year. Ankle swelling, treated by bedrest and elevation,
occurs infrequently after biopsy. Risks include the rare complications
of local infection or bleeding. A small scar will remain at the
biopsy site.
Biopsy, Skin
The skin area to be biopsied is cleaned with iodine and alcohol.
A local anesthetic numbs the area, and a 1/4-inch piece of skin
is removed with a special tool.
Discomforts and risks: Pain at the biopsy site should
be minimal; bleeding and infection are rare. Biopsy wounds usually
heal with a very small, nearly unnoticeable scar, but sometimes
a raised scar or visible lump may result. However, the biopsy
will be taken from a place on your body that is not easily seen.
Blood Drawing (Venipuncture)
During this study, no more than ___ teaspoons (or ___ cups)
of blood will be drawn. You may experience some discomfort at
the site of needle entry, and there is a risk of a "black-and-blue"
mark. There is a remote risk of fainting or local infection.
Bone Marrow Aspiration
The purpose of this procedure is to collect cells from your
bone marrow. It will be done in the hospital/clinic and will
take about 15 minutes. While you lie on your stomach, the skin
over your hip bone will be cleaned with alcohol and iodine. A
local anesthetic (numbing medicine) will be injected under the
skin and into the outer covering of the bone. After the area
is numb, a needle will be inserted into the bone. A syringe will
be attached to this needle and a rapid suction movement (aspiration)
will be made. The aspiration may be repeated several times so
that an adequate number of bone marrow cells is obtained. There
are no limitations on your activity after the procedure is over.
Discomforts and risks: You will feel mild burning for
several seconds until the numbing begins. You will feel a pushing
sensation, but no pain, as the needle enters the hip bone. As
the marrow is aspirated, you may feel a sharp pain, lasting 1
to 2 seconds. There may be a small amount of residual pain, but
within an hour or 2 you should feel normal. There is a remote
risk of fainting during the procedure and of bleeding or local
infection at the aspiration site.
Bronchoscopy
This procedure takes 30 to 90 minutes and involves passage
of a long, narrow, flexible tube (bronchoscope) through the nose
or mouth into the airways of the lung. Before passage of the
tube, the nose and throat are sprayed with local anesthetic (numbing
medicine). When the bronchoscope has been steered into a specific
airway of the lung, a small amount of sterile water may be squirted
through it into the lung and immediately suctioned back, washing
off some of the cells lining the airways. The fluid and cells
are then analyzed in the laboratory.
Discomforts and risks: There is no known risk of this
procedure in individuals with normal hearts and lungs, but as
a precaution we will monitor heart rhythm and rate, and place
a small needle in an arm vein. There may be some discomfort when
the bronchoscope is passed through the nose, and occasional patients
experience gagging and an urge to cough when the bronchoscope
is passing through the throat and the vocal cords. A sore throat
and mild hoarseness may persist for several hours; these resolve
routinely within a day. Occasionally, subjects have temporary
fever following bronchoscopy; in hundreds of studies carried
out to date by the Pulmonary Branch, such fevers have gone away
promptly and have required no therapy other than an aspirin-like
medication.
Computerized Axial Tomography (CAT
or CT) Scan
A CAT (computerized axial tomography) scan requires that you
lie still for a short time while x-ray images are formed. It
may also require an injection of dye through a needle placed
in an arm vein.
Colonoscopy
A flexible instrument with a special system of lighting (colonoscope)
permits your doctor to examine the large intestine. Before the
procedure, an intravenous sedative will be given to relax you.
Then a flexible tube will be inserted into your rectum and advanced.
The procedure takes 20 to 90 minutes. Your doctor may want to
biopsy (cut out a small piece for diagnosis) suspicious areas.
Discomforts and risks: The IV sedative may slow or,
very rarely, stop breathing, but this can be reversed by other
medications. Patients who have abnormal or replaced heart valves,
pacemakers, artificial joints, or vascular surgery grafts are
at risk for infection; antibiotics may be administered before
and after the procedure. The risk of perforation of the colon
is 2 to 4 in 1,000 cases, with possible bleeding or infection
that might require a blood transfusion, antibiotics, or surgery.
Rarely, irregular heart beats and ruptures of the spleen have
occurred. Death has followed the procedure in approximately 1
of 10,000 studies.
Electrocardiogram (EKG, ECG)
A recording of the normal electrical activity of your heart
is taken by placing electrodes (pieces of metal attached to wires)
on the skin of your chest, arms, and legs. There is no discomfort
and there are no risks.
Electroencephalogram (EEG)
A recording of the normal electrical activity (waves) of your
brain is taken by securing electrodes to your scalp with a glue-like
substance (collodion), that can be removed with a substance similar
to nail polish remover (acetone). We will measure your brain
waves while you are lying quietly, breathing deeply (hyperventilating),
watching bright flashes of light (photic stimulating), or sleeping.
The session will last for 1 to 2 hours.
Discomforts and risks: Both the glue and the remover
acetone have strong odors but do not have any harmful effects
when used for a short time.
Electromyography/Nerve Conduction
Study (EMG/NCS)
Electromyography (EMG) measures the electrical activity of
muscles. It involves insertion of a needle into a muscle to record
its electrical activity. You may experience pain at the site
of needle entry. Hazards include the slight possibility of infection
or bleeding.
Nerve conduction studies measure the speed with which nerves
conduct electrical impulses. These studies are performed by taping
a wire on the skin to record the impulses and another wire on
the skin over the nerve to deliver a small electrical stimulus.
You might experience discomfort during the nerve stimulation.
If this is too uncomfortable, you can stop the test.
These two studies usually are performed during the same session
and take from 1/2 to 1 hour.
Endoscopy, Upper Gastrointestinal
This procedure takes less than 30 minutes and involves the
passage of a long, flexible tube (endoscope) through the esophagus
(swallowing tube), stomach, and duodenum (small intestine). Your
throat will be sprayed beforehand with a local anesthetic (numbing
medicine), and an intravenous medication will be given to relax
you.
Discomforts and risks: Patients sometimes experience
a sore throat, gagging, nausea, or bloating. The overall complication
rate for upper gastrointestinal endoscopy is slightly more than
1 in 1,000 cases. These include bleeding (about 3 in 10,000 cases),
aspiration (inhalation) of stomach contents into the lungs, abnormal
heart rhythms, or lower-than-normal breathing rates (approximately
6 in 10,000), and puncture of the wall of the esophagus (3 in
10,000) cases. There is an extremely small risk of puncturing
the wall of the stomach or intestine. Puncture of any of these
organs could be followed by bleeding or infection that might
require blood transfusion, antibiotics, or surgery. Death followed
the procedure in 7 of 10,000 cases.
Evoked Potentials
These tests are similar to the electroencephalogram (EEG)
and last 1 to 2 hours. During the study of somatosensory evoked
potentials (SEP), nerves in the arms and legs are stimulated
electrically. During the visual evoked potentials (VEP) study,
you will be requested to watch black-and-white checks moving
on a TV screen. During the study of brainstem auditory evoked
potentials (BAEP), you will be asked to wear headphones and will
hear several clicking sounds of different pitches; each ear will
be tested separately. In each study, responses are recorded from
electrodes (pieces of metal attached to wires) placed on the
scalp, neck, and back.
Discomforts and risks: Similar to those of EEG recording.
Electrical stimulation of nerves may cause some stinging sensation.
Glucagon Test
This test determines whether your liver releases glucose (sugar)
normally. A catheter is put into an arm vein, and the hormone
glucagon is injected into an arm muscle (or another arm vein).
Blood is drawn periodically, as you lie quietly for the next
3 hours.
Discomforts and risks: You will have some local pain
at the needle sites. Glucagon causes nausea and occasionally
vomiting in some people.
Lumbar Puncture (Spinal Tap)
The lumbar puncture (LP) or spinal tap lets us study cerebrospinal
fluid (CSF) to learn some of what is going on in the brain and
spinal cord, which are bathed by CSF.
You will lie on your side, and a local anesthetic will be
used to numb an area in your lower back. Then, about 2 tablespoons
of spinal fluid will be collected.
Discomforts and risks: Some patients may develop a
headache or backache following an LP. Prolonged headaches develop
in only 1 in 50 to 1 in 200 subjects and usually subside within
1 week. The likelihood of having a headache may be diminished
by lying flat in bed for 24 hours after the LP.
In rare cases, post-LP headaches persist for months or years.
Such headaches may result from continued CSF leakage at the LP
site. If the headache lasts longer than 1 week, a "blood
patch" can be done. A small amount of blood from your arm
vein is injected into the area of the supposed leak to try to
seal it. The blood patch relieves the headache in most (95 percent
in some studies) patients.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) uses a strong magnetic field
and radio waves to demonstrate structural and chemical changes
in tissue. This technique is more sensitive than x-ray in some
diseases and carries no radiation risk. You will lie on a table
in a space enclosed by a metal cylinder (the scanner itself).
The time required to stay within the cylinder will be about ___
minutes/hours. You will be asked to lie very still for 10 to
15 minutes at a time.
Discomforts and risks: Patients are at risk for injury
from MRI if they have metal objects in their bodies, such as
pacemakers, aneurysm clips (metal clips on the wall of a large
artery), metallic prostheses, cochlear implants, or shrapnel
fragments. Welders and metal workers are also at risk for eye
injury because of unsuspected tiny metal fragments there.
Individuals with fear of confined spaces may become anxious
during MRI. You will hear a thumping noise created by the radio
waves forming the images. You will feel no pain, but you may
find the noise and the closed-in space discomforting. You will
be observed at all times by the operators and will be able to
speak to them; you can be moved out of the machine at your request.
Nerve Conduction Study
See Electromyography/Nerve Conduction
Study.
Oral Glucose Tolerance Test
This is the routine test used for many years to diagnose diabetes.
A needle with small, flexible plastic tubing (catheter) is placed
in an arm vein to withdraw about a teaspoon of blood before you
drink a sugar solution, and at 30 minutes, 1 hour, 2 hours, and
3 hours afterwards.
Discomforts and risks: Some people experience nausea
after drinking the sugar solution. Rarely, a bruise or minor
infection may occur where the catheter needle entered your vein.
Upper Gastrointestinal Endoscopy
See Endoscopy, Upper Gastrointestinal.
Venipuncture
See Blood Drawing.
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