Excerpts from the Field Neurological Evaluation Manual by Andrea Zaferes and Walt "Butch"
What are we looking for?
In parts I and II we looked at the function of Field Neurological Evaluations and
how to incorporate risk factors into the decision making process. In this part we will
examine the specific steps of performing a FNE. Test for loss of sensation by gently
touching various parts of the patients body while asking the patient if anything is
felt, and if so, where. Test for weakness by asking the patient to perform various
exercises that are evaluated on the basis of body symmetry and evaluator experience. For
example, you hold the patients left leg down and asks her to raise the leg as hard
as she can. You then test the right leg to see if her legs are equally strong. For you to
recognize bilateral weakness it helps to have practiced performing FNEs on uninjured
people. Test for dexterity and coordination by asking the patient to perform tasks
requiring such skills. Test for level of consciousness by observing how the patient
answers questions and follows commands. Ask the patient if any pain, discomfort, tingling,
numbness, or weakness is present. Ask if any other symptoms are felt.
Communication and Questioning Techniques
Accuracy is more important than volume when it comes to information. Non-leading
questioning techniques are crucial for obtaining accurate information. If patients are
asked whether or not they can feel something they have a 50-50 chance of providing a
correct answer regardless of whether or not they experience any sensation. Always keep in
mind that the majority of patients try to deny a problem, while others will become overly
concerned about nonexistent or minor irrelevant symptoms. Questioning techniques should
not only provide zero clues, but should allow the evaluator to detect misinformation.
Keep in mind the following points and have a friend evaluate you on them during practice
The key is to provide as few clues as possible. The
patients answer should be strictly based on the presence or lack of sensation,
strength and coordination.
1. Listen to your voice inflection. Be
careful that the inflection does not correlate with your actions. For example, some
evaluators end in a higher inflection when actually touching the patient than when not.
2. Use location verifications to check "yes"
answers. When the response is "yes" to a "am I touching
you" question, ask the patient what area was touched. If the patient had given a
false "yes" answer, then the patient will probably not be able to tell you the
location of the touch.
3. Avoid left/right or top/bottom patterns.
If you always go from left to right for example, then the patient may be able to provide a
correct location after a false "yes" answer using the clues provided by a
consistent left/right pattern. Use a random pattern of repeated tests on one side,
followed by a few left/right - right/left switches, top-bottom, etc.
4. Use nonleading questions such as:
"Am I touching you?" "Do you feel anything?" Avoid questions that
imply your actions: "Do you feel me touching you?" "Do you feel this?"
If you are not touching the patient and you ask either of the last two questions the
patient could become quite concerned, incorrectly thinking that he or she is experiencing
5. Avoid asking for left or right patient answers.
Some people do not know left from right on a good day, and many of us confuse them on bad
days. When asking location verification questions during a FNE, right/left answers may
appear confused or wrong when actually the problem is quite normal and not indicative of a
neurological problem. Ask patients to "wiggle the fingers on the side Im
touching," "bend the knee of the leg Im touching," or "turn your
head to the side Im touching." This not only avoids left/right problems, but
also provides additional information on patient movement capabilities.
6. Maintain a calm, friendly, competent tone of voice, no
matter what results the FNE produces. Gain the patients trust and
confidence to relax both of you. This will make the patient more comfortable and compliant
with rescue and first aid procedures. If you find yourself raising your tone of voice, or
sounding nervous or even hysterical, try thinking of how you would talk to a competent,
but nervous, child. Talk slowly and clearly. When you become confident at performing FNEs,
learn how to add humor and jokes to the communication and questioning process. A smiling
patient is far better off than a nervous or scared one. Your competent and joking manner
tells the patient, "Hey, it cant be that bad, things must be under control if
we can still joke around."
7. Whenever you discover a potential abnormality,
such as unequal pupil size or weakness in one extremity, ask the patient if this normally
occurs, and, if so, does he know why. For example, unequal pupil size can be present at
birth and extremity weakness can have been caused by atrophy from an old injury. If
possible, record this information.
Performing a basic head to toe, lying down, FNE.
Sensation tests can be done gently with a finger or a fluffy cotton swab. You can keep
cotton swabs taped to your Field Neurological Checklist Slate.
To discover changes or lack of sensation the evaluator must gently
touch various locations on the patients body. To understand what areas to touch, a
basic understanding of segmental fields of sensation, known as dermatomes, is important.
Each segment of the spinal cord has a peripheral sensory nerve that innervates a segment
of skin known as a segmental field or dermatome. When a particular segment of skin, the
pinky for example, is touched, peripheral nerves carry the information to the cervical 8
(C8) section of the spinal cord, which sends the information to the brain. The result is
the person feels a sensation on his pinky. Information can be sent in the opposite
direction also, from the spinal nerve to the corresponding dermatome. Damage to a spinal
or peripheral nerve can result in numbness, tingling and/or pain in the corresponding
Look at Figure 1. The Field Neurological Man is a dermatome map. Each letter represents
the area of the spine, (C=cervical, T=thoracic, L=lumbar, S=sacral) the nerve is located.
For example, C2 is the nerve between the first and second vertebrae in the cervical (neck)
region, and L5 is the lowest nerve of the lumbar vertebrae located in the lower torso
A person with central nervous system damage, as caused by Type II
decompression sickness for example, could have seemingly normal sensation in one
dermatome, with numbness in a neighboring dermatome, depending on which spinal nerves are
being affected. As time progresses, the number of dermatomes affected may increase,
presented as spreading numbness, but our goal is to discover any possible problems as
early as possible. Keep in mind that injury to the spine can produce bilateral symptoms,
so if a change in sensation is found in a set of dermatomes on the patients right
side, be sure to check the same areas on the left side.
Learning how to perform the FNE
Read the following description of a basic evaluation straight through to get a sense of
what a FNE involves. Re-read it a second time more slowly and take notes. Re-read it a
third time, or have someone else read it to you as you perform the actions on a mock
patient. Practice performing the FNE using the FNE Checklist as a guide. Frequent
references to a checklist while working with an actual patient is recommended.
Once you feel proficient with the Basic FNE, add in the advanced steps.
The next step is to teach someone else how to perform the FNE to increase your skill and
learning retention. Have your "student" practice on you as well so you can learn
what it feels like to have a FNE performed on you. This is important, and it will improve
your skill level.
After obtaining consent, have the patient remove the exposure suit and lay in a
comfortable, supine position in a shaded, private area. If dyspnea (breathing difficulty)
is present, the patient may be more comfortable with the torso elevated. Remember that if
s/s are obvious, do not delay oxygen administration and EMS activation. The FNE can be
performed after EMS activation and during oxygen administration. The sun or other light
source should be at your back to shield the patient's eyes. Kneel behind the patient's
head and professionally explain what you are about to do.
While performing the exam, it is important to continually maintain communication with the
patient to assess awareness and level of consciousness. Ask the patient his name, the date
and where he is and has he been diving. Does he have any pain, tingling, numbness,
weakness or paralysis? The key findings to look for and note are any deficits or
asymmetries in sensation, motor strength, coordination and level of consciousness.
Note the following if it occurs: Did the patient lose control of bladder or bowel
function, or does he feel the need to void, but is unable. Are there any manifestations of
out-of-character behavior, or changes in the patients personality? Could any
previous injuries account for the manifesting signs and symptoms? Is the patient easily
Head & Neck
Begin by kneeling behind the patients head, with the sun or artificial light source
behind you if possible. Most patients will immediately look up at you, but if they
dont, ask them to. Examine the patient's eyes and pupils. Note pupil size. Are they
equal? Are they dilated or constricted? Unequal pupils could indicate a cerebral problem.
If this sign is noted, make sure to ask the patient if her pupils are normally of equal or
With the sun or other light source behind you, gently move sideways allowing the light to
hit the patients eyes and check for pupil constriction and dilation. If such light
is not available, have the patient close her eyes for few seconds and then open them. Are
pupils equally reactive? Do they react at normal rates or are they unusually slow? If you
are not previously trained in this skill, practice on as many people as possible in
different environments to learn how normal pupils behave.
2. Scalp Sensation:
Gently palpate (touch) areas of the scalp while asking if the patient feels anything and
if so, where. Make sure to move both your hands and arms equally, regardless of whether or
not they are making contact with the patient, to prevent giving the patient location cues.
3. Eye Movement:
During the scalp sensation checks, move your own body from side to side, backwards and
forwards and watch the patients eyes as they follow you, and check if the eyes track
If for whatever reason the patient will not follow your body movements with her eyes, ask
her to look at your finger as you move it vertically and horizontally across her face,
approximately a foot away.
4. Visual Fields, Peripheral Vision:
Ask the patient to look straight up into the sky. Make two fists and place them gently on
the patients temples. Raise your thumbs with the knuckle lined up at the tail end of
the eyebrows. (See photo.) Wiggle the last joint of one thumb and ask if she sees anything
wiggling, as her eyes remain focused on the sky. If yes, ask her to wiggle the fingers on
that side. Test both eyes one at a time and then together. If she says no, raise your
thumbs slightly and try it again. Note how far up her eyebrows your thumbs must be before
she can see them. A person with average peripheral vision should see your thumbs in the
Lower peripheral vision will be tested during the torso check.
If a problem presents, remember to ask the patient if her peripheral vision is normally
normal or if she has a previously diagnosed peripheral vision problem.
5. Forehead Sensation:
Gently touch various areas on the forehead and ask the patient where she feels the
sensation. Ask whether or not she feels anything when you are not touching her. Remember
to employ both your arms when you are and are not touching her.
6. Ears & Hearing:
Test pina (outer ear) sensation. Gently touch an ear and ask if anything is felt. Randomly
test each ear separately and together.
Rub your thumb against your other fingers approximately 2-3 inches from the patients
ears, one at a time and then together, to test for hearing. Try it on yourself now to hear
how loud a sound it is. Ask the patient to wiggle her fingers or foot on the side that she
hears the sound.
Ask the patient if she hears any unusual sounds such as ringing, roaring or humming.
7. Head Turning:
Place your hands on either side of the patients head and ask the patient to turn her
head toward the direction of the cheek you are gently touching with your index finger.
Remember to always ask the patient to push hard when testing for strength. Are the left
and right head turns equal in strength and flexibility? Did the patient have cheek
sensation - remember, if the patient could not tell which sided to turn, then there was
lack of cheek sensation.
8. Pulse, Trachea, Carotid Artery Quality and Neck Fullness:
Reach down and check the carotid pulse on one side at a time. This can be your actual
pulse check which means taking the pulse for 30 seconds and multiplying by two to get the
number of beats per minute. Avoid taking pulse rates for less than 30 seconds to prevent
inaccuracies. Note the quality of the pulse (strength and regularity). Write down the rate
and quality with actual time taken.
While taking the pulse rate, notice the carotid arteries for equal
appearance. If one or both carotid arteries appear to bulge, gently help the patient sit
up if possible and see if the bulging disappears after a few seconds. If the bulging
remains, ask the patient if the arteries normally bulge and, if not, write the information
down. Arterial bulging could be a sign of a blockage or other problems. If such a bulge
does occur, there will most likely be other obvious signs present.
At the same time, notice if the patient swallows and whether the trachea is straight or
deviated. A deviated trachea could be a sign of a tension pneumothorax. If the patient
does not swallow spontaneously then ask her to do so after the pulse check while watching
the trachea. If the patient cannot swallow ask her why she thinks she cannot and write the
information down. She could be dehydrated, or perhaps there is a neurological problem.
This is also a good time to take a respiration rate for 30 seconds. If the patient thinks
you are still taking her pulse, then there is less chance she will consciously or
unconsciously alter her breathing.
Check the neck for overall swelling or fullness which could be caused by mediastinal
Check the base of the neck and collar bone region of the upper torso for crepitus
(crackling sound) and subcuntaneous swellings caused by air under the skin from a
subcutaneous emphysema lung overexpansion injury.
Check for a rash on the upper torso, which could be from skin bends, a type of
decompression sickness usually associated with chamber dives or very long, shallow dives.
Check for a mottling of the skin in the upper torso, which could be from decompression
sickness more often associated with deep diving. Mottling has been known to be followed by
central nervous system decompression sickness.
9. Jaw Clench Strength:
Place one hand on the patients lower jaw and ask her to try to open her mouth. Have
the patient open her mouth, gently take hold of her chin, and ask her to close her mouth.
10. Cheek Sensation, Tongue Push, Tongue Wave and Smile
Ask the patient to look up at you as you sit slightly back. Place both your hands near her
mouth, gently touch one cheek near the mouth area with one finger, and ask her to touch
your finger with her tongue. The patient will invariably reach her tongue out of her mouth
to touch your finger. Before she makes contact, say humorously, "no, from the
inside." Then you can observe the smile reflex. Humor is an excellent way to break
the ice, calm nerves and develop a trustful interaction.
Clarify yourself and tell her to push her tongue hard against the spot she feels
If you were not successful at eliciting the smile reflex with humor, ask the patient to
smile, frown and smile. Always end with a smile. You can also ask her to raise and lower
Ask the patient to stick her tongue out and wave it quickly up and down vertically and
then horizontally. Check for symmetry.
11. Shoulder Shrug and Shoulder Sensation:
Place your hands gently under each of the patients shoulders. Inconspicuously and
gently touch behind one shoulder with a finger and ask the patient to push hard up against
your hand with the touched shoulder. Do each shoulder separately and together in random
12. Index Finger to Nose:
Keep your hands against the patients shoulders. Touch a different area of the
shoulder than you tested earlier and ask the patient to reach up with the arm on that side
and touch your nose with her index finger. Test each arm separately and together.
If something with a pleasant and recognizable smell is readily available, ask the patient
to close her eyes, hold the object 5-6" from her nose and ask if she smells anything
and if so what does it smell like. Acceptable smell objects include suntan oil, orange
peel, and cologne. Never use a noxious smell, as it will lose you patient's trust, and can
further stress the patient.
14. Respiration Rate and Quality:
If you did not take a respiration rate when performing the head and neck portion now is
To find an accurate respiration rate it is important the patient does not know. One trick
is to pretend to take her radial pulse (on the wrist above the thumb) by placing her wrist
on her upper abdomen. Instead of taking her pulse, feel and watch her abdomen and lower
chest rise and fall. Normal adults respiration rates are between 12-22 respirations per
Note the quality of the respirations as well. Are they shallow, normal, full, regular,
irregular? Does one side of the chest not rise as high as the other, which could indicate
a tension pneumothorax. If the patient is having difficulty breathing, ask if there is any
pain upon inspiration or expiration and note which. Note that a pain in the mid to upper
back during inspirations can also indicate a pneumothorax. If breathing is rapid, notice
how many words the patient says between respirations, which will help you easily monitor
changes in rate over time.
15. 3 Side Arm Sensation:
Look at the arms on the Dermatome Map figure and see that from the shoulder down there are
approximately six dermatomes. The goal is to check as many dermatomes as possible. With
the patients arms laying on the ground next to her, gently reach over both arms and
alternately lightly touch test her arms separately and together. Remember to make sure
that from her visual field, she sees both your arms moving near both her arms at all times
to avoid giving her any location cues.
If you test the front, inside and back of the arms from top to bottom, enough areas will
be checked. Remember not to look at the arm you are touching to avoid giving the patient
16. Arm Strength:
Place your hands on the patients upper and lower arm and ask her to raise her arm as
hard as she can as you try to keep her arm on the ground. Test both arms.
17. Hand Sensation and Clench:
With the patients arms still laying down, reach back, gently touch the area of one
hand between the thumb and first finger, and ask her to reach up and squeeze your two
fingers hard with that hand. This task tests for sensation in the C6 area of the hand,
coordination in reaching up and grabbing your finger, in addition to hand clench strength.
Do each hand separately and together.
Remember, if the strength feels weaker than you would expect from that patient, ask the
patient to repeat the task with greater effort.
18. Finger Sensation and Tricep/Bicep Strength:
Ask the patient to place her hands on her abdomen with her fingers spread out, keeping her
hands separate from each other (see photo). Look at the dermatome map to see that the
fingers are controlled by three different nerves, C6, C7 and C8. In this task, you will
test for sensation in each of these three areas while asking the patient to demonstrate
tricep, bicep and secondary muscle strength.
With the patient still lying down, place your hands a few inches from hers. With one
finger gently touch one of her C7 fingers, and then rest both your hands on top of her
hands. Ask her to push the hand you just touched up toward the sky against your hand. Pull
your hands away from hers, touch a C6 finger, rest your hands back down on hers again and
ask her to raise the touched hand toward her head. Again lift your hands, touch a C8
finger on the same or the other hand, replace your hands on hers, and ask her to push the
touched hand down toward her feet.
19. Ribs, Back, Sternum Sensation:
Ask if the patient feels any discomfort or unusual sensations in the chest, back, lower
back, etc. areas.
Look at the dermatome map to see how many sections of the torso should be checked.
If the patient is a woman, test for sensation from the abdomen to neck, up the torso
midline. If it is a man, then test up along the left and right sides of the abdomen chest.
The latter is a more thorough technique because left and right peripheral nerves meet at
the midline, so loss of sensation on one side could be missed with the midline method.
But, it is important to keep a woman comfortable with all the evaluator's actions.
20. Lower Peripheral Vision
Lower peripheral vision can be checked during this sensation check. Extend your pinky and
thumb, and curl in the rest of your fingers to your palm. Ask the patient to maintain
focus on the sky. Touch the patient with your pinky, while keeping your thumb upstretched
towards the sky. Wiggle your thumb and ask the patient if she sees anything wiggling.
Randomly alternate the sensation and vision checks from the waist to the neck. Normal
peripheral vision means the patient can see your thumb wiggling at the xiphoid process
level. Try it yourself. If the patient is obese, you can bend the pinky horizontal to
lower the thumb.
Check the stomach for marbling or mottling. Ask the patient if any discomfort or nausea is
present. Gently press the four quadrants of the abdomen by pulling the fingers back and
slowly rocking palm into the abdomen from the heel of the hand to the upper palm. Ask if
any pain or discomfort is felt with these four maneuvers. This is a good time to discover
if the patient's bladder feels full, and if the patient reports to have difficulty
Gently touch the abdomen and ask the patient how far the sensation is from her belly
button. If she has any boat knowledge, tell her her head is the bow, and looking down on
her as a boat, where are you touching her, port, starboard, stern or bow? If she doesn't
know these terms, then tell her her head is 12:00 o'clock and her feet are 6:00 o'clock,
touch her abdomen and ask her what time would that represent. This checks for confusion,
and also helps keep the patient's mind occupied and calm. Remember, use humor frequently
to further relax the patient.
Check for hip sensation by gently touching the hips separately and together.
23. Thigh Sensation
Making sure to keep both your arms moving, lightly touch the inside, top and outer areas
of both legs to check for sensation. Ask the patient where the sensation is felt, and
occasionally ask the patient to wiggle the foot or hand on that side.
24. Leg Raise Strength
Place one hand on the thigh and one hand on the shin of one of the patient's leg. Lean
your weight onto the leg and ask the patient to raise the leg without bending the knee.
Check the other leg. Note any symmetry differences, and if there are ask about previous
injuries and athletics/occupations that might be responsible. Also, look at the patient to
decide if the leg strength demonstrated matches what you would expect of that individual.
25. Foot Sensation, Toe Sensation, Foot point, Foot Retract,
Foot Movement side-to-side, and Babinski's Reflex.
Position yourself behind the patient's feet. Lightly touch the toes of one
foot, then with both hands hold the top of both feet with the palm of your hand and ask
the patient, "flex the foot I just touched." This checks toe sensation and foot
retracting muscles. Randomly check both feet. Lightly touch the side of one foot, then
hold the sides of both feet and as the patient, "push outward against my hand with
the foot I just touched." Lightly touch the inside of one foot, then hold the inside
of each foot and ask the patient, "push inward against my hand with the foot I just
touched." Run your finger, a pen cap, etc. quickly with some pressure, from the heel
up to the toes in the center of the patient's sole. Make sure the toes reflexively bend
outwards and then relax back to normal (Babinski's reflex). If the toes move inward, there
may CNS damage. If the toes do not move at all ask the patient if he or she is normally
ticklish. If yes, then the lack of toe movement could indicate CNS damage. Some people
normally have very little or an imperceptible amount of movement. Next, hold the soles of
both feet, and ask the patient to push your hand down with the foot you just tested.
COMMUNICATIONS AND ACCIDENT REPORTING
Who should you call first when faced with a dive accident? Although many divers would
immediately answer "DAN," that is usually not the correct answer. When a problem
is first suspected the EMS should be activated immediately and if this problem occurs on
the water, the Coast Guard may also be contacted. It is important to know how EMS can be
contacted as different locations require different telephone numbers. Obtaining this
information should be part of pre-dive planning.
After we know what ambulance company has our patient and hopefully what hospital he or she
is going to then we should immediately contact DAN so that DAN can contact the receiving
doctor. The arriving EMS should be given DANs emergency number to give to the
hospital. This does not exclude calling DAN first with any normal questions about signs
& symptoms during a possible emergency. For other than medical emergencies please call
DAN at (919) 684-2948.
Why should the EMS be activated before DAN and when should DAN be
called? In the past, divers sometimes tried to transport injured divers directly to a
chamber. Sometimes the chamber was no longer in operation or it was already being used.
Sometimes the injured diver needed emergency room treatment, instead of hyperbaric
treatment so precious time was wasted by not getting the diver to a closer hospital.
Generally divers dont carry or have training in oxygen administration, suctioning,
basic life support, etc., so can do little for the needy diver during transport. Often a
Paramedic or an EMT can alleviate and begin treatment for many dive injuries such as a
pneumothorax, shock, and respiratory/circulatory problems.
When EMS is called, they will need to know the patients
gender, age, name, chief complaint and current physical status (e.g., is there breathing
and heartbeat, conscious or unconscious), as well as the location for picking up the
patient. Let DAN communicate with the receiving hospital, and if hyperbaric treatment is
necessary, arrange for transport and reception to a ready and waiting recompression
Practice the FNE one section at a time with two friends so one can act as a patient and
one can be an assistant. Good luck.
ARTERIAL GAS EMBOLISM (AGE)
Lung overpressurization can result in the introduction of gas bubbles in pulmonary
arterial blood flow in pulmonary venous capillaries. These emboli can obstruct arterial
blood flow to the heart and/or brain (cerebral arterial gas embolism, CAGE), as well as to
other parts of the body. This can progress to unilateral or bilateral paralysis as well as
cardiac and respiratory arrest. It could also lead to symptoms as subtle as minor tingling
and/or the lack of an ability to maintain mental concentration and focus.
A case history of the latter was reported by an instructor and chamber operator in
Bonaire, who described a middle aged woman who took a private resort course from her. The
woman had difficulty equalizing so she was not able to complete the course, and never
descended deeper than 4 feet in confined water. Several hours later the woman returned to
her instructor and complained that she could not keep her concentration on anything. She
couldn't keep her mind focused. She was a little worried about it. The Instructor sent her
immediately to a hyperbaric physician who later reported that when he questioned the woman
if she had been diving, she kept insisting no. Finally he asked her if she breathed off a
regulator, and she reported yes, but she didn't actually dive because of equalization
problems. No problems other than the lack of mental concentration were discovered upon
neurological examination. The woman underwent a standard test of pressure in the
recompression chamber and reported an immediate clearing of her head. She was given a full
Table 6 Treatment with complete symptom resolvement.
The Heart and AGE:
Another type of s/s presentation that may be difficult to recognize as an AGE is the
"heart problem, heart attack" presentation. It has been recorded that AGE
fatalities are sometimes incorrectly diagnosed as myocardial Infarction (heart attack) due
to s/s presentation and standard autopsy procedures. For AGE to be recognized during an
autopsy, special procedures must be used, such as opening the skull first, to prevent the
introduction of artifact air in the vasculature.
The heart can be affected by an AGE directly and/or indirectly. Directly, bubbles can
enter the coronary arteries and cause a blockage resulting in myocardial infarction. Air
entering the left atrium and ventricles can adversely affect cardiac function. Indirectly,
bubbles blocking blood flow to the vasomotor center in the lower brain stem could disrupt
normal heart action.
Therefore, pulse quality and rate, and blood pressure should be carefully monitored and
duly recorded. If a blood pressure cuff is not available, monitor the radial pulse of a
patient since a minimum systolic pressure of 80 mmHg is necessary for a palpable radial
pulse. A systolic pressure of 80 mmHg or less is indicative of hypotension (low blood
pressure) and shock.
Case history for the 1993 DAN accident & fatality report.
Decedent was a 50 year old, obese male diving in tropical, current free, shallow water
(12-15 fsw). He indicated to his companion a need to surface and immediately become
unconscious after stating he was very tired. Cardiac arrest followed immediately and
resuscitation was not possible. Autopsy found air in both ventricles, suggesting death may
have been due to coronary artery air embolism in view of sudden death. There was
borderline cardiomegaly (enlarged heart) but no other significant findings.
A.G.E. is most often described by CAGE and cardio-affected AGE signs and symptoms. It is
of interest to note however, that AGE is more of a systemic problem than previously
believed. Studies have demonstrated that AGE patients had as high or higher blood levels
of CPK and GOT than nondiving myocardial infarction victims. CPK and GOT are digestive
enzymes found in lysozomes, membrane bound organelles in cells. When cells are injured or
killed, these lytic enzymes are released to autodigest, autophagocytize, the no longer
functional cells. These studies, therefore, indicate damage to organs other than the
brain, which may become important to future changes in clinical treatment of AGE patients.
Smith, & Neuman (1994) found elevation of serum creatine kinase in A.G.E. patients,
which demonstrates biochemical evidence of muscle injury associated with A.G.E.
Smith, Van Hoesen & Neuman (1994) found that in contrast to stroke patients, and
similar to DCS patients, A.G.E. patients showed an elevated hematocrit at presentation of
s/s and hematocrit falls during hospitalization. They also found a significant correlation
between the magnitude of the hematocrit fall and the eventual neurological outcome. The
hemoconcentration in DCS patients has been theorized to be due to the greater permeability
of injured endothelium. It is possible that A.G.E. similarly injures vascular endothelium.
A.G.E. and Pulmonary Barotrauma
Harker et al. (1993) found evidence of pulmonary barotrauma in 42% A.G.E. patient chest
radiographs. They found 52% of these 31 patients had pulmonary infiltrates.
The brain controls both physiological and mental functions so the s/s of CAGE are
dependent on where blockages of blood flow cause ischemia (oxygen deprivation) and cell
death. CAGE s/s can be as major as death and as difficult to recognize as confusion and
If blood flow to either the left or right brain is severely obstructed then unilateral
paralysis may present. Blockages in cerebral capillaries could present as spotty signs
distributed in various locations of the body.
Signs and Symptoms
Typically occur within the first 10-15 minutes of surfacing. The set of s/s are sometimes
similar to those presented in cerebral cardiovascular accidents (strokes). They include:
"Out of Character Behavior "Confusion
"Unconsciousness "Dizziness "Unilateral or Bilateral Motor problems"
"Uni-lateral or Bi-lateral Paralysis "Numbness & Tingling"
"Weakness "Loss of sensation"
"Chest Pain "Headache "Nausea "Convulsions"
"Speech/Visual Disturbance "Gasping, Shortness of Breath"
"Dilated Pupil(s) "Heart Attack signs/symptoms "Shock"
"Near Drowning or Drowning signs such as hemopytsis"
"Liebermeister's sign - a sharply defined pale mottling on the tongue"
First Aid Treatment:
Immediate administration of high flow oxygen with basic life support as dictated.
Transport the patient or victim to medical authorities and hyperbaric treatment as soon as
possible with care taken when transportation involves altitude changes greater than 500 -
750 feet. Perform FNEs every 15-20 minutes while waiting for EMS, to evaluate s/s
If you are part of the responding EMS, perform FNEs enroute to the hospital if possible to
record s/s progression. If the patient is breathing then administer oxygen with a demand
Note on oxygen administration:
Although many EMS protocols involve a non rebreather mask for
breathing patients, DCI is aided by the highest percentage of oxygen delivery for a
variety of reasons including, decreasing the partial pressure of alveolar nitrogen, edema
reduction through vasoconstriction, increasing offgassing by increasing nitrogen tension
between tissues and blood, decreasing areas of ischemia, and more. The difference in
delivery between a non rebreather mask and a demand valve mask can be almost 25%, with a
75% oxygen delivery and 99% oxygen delivery, respectively. If the patient is breathing so
weakly that the inhalation is not strong enough to crack the demand valve open, then
administer oxygen with a non rebreather mask set to 15 L/min.
Do not confuse a demand valve with a positive pressure button. Positive pressure buttons
are found on demand valves, and not all demand valves have positive pressure buttons. For
example the demand valves sold by DAN and Lifeguard Systems are designed solely for
breathing patients and lack "pp" buttons. Positive pressure buttons are used to
mechanically ventilate a non breathing patient. If your local protocols removed demand
valves from your ambulances because positive pressure buttons are no longer used by EMTs,
then try to get one back on board for the breathing dive accident patient.
What about the Trendelenberg Position?:
The Trendelenberg position was originally designed as a surgical position on an upside
down "V" shaped table for groinal surgery. The patient's hips are positioned
higher than the heart, the heart is positioned higher than the head, and the legs lay
downward on the other side of the "V." A function of the position is to keep the
intestines from falling down in the way of the groinal area.
The Trendelenberg position was adapted to the AGE accident patient with several
theoretical functions: if used immediately after surfacing, the position might trap air in
the left ventricle to keep it from traveling to the brain; allow the increased cerebral
blood pressure, created by the inverted position, to push arterial emboli deeper into the
brain into smaller capillaries, thus decreasing the number of obstructed vessels; increase
blood pressure to force blood past the obstructing emboli.
The use of Trendelenberg is controversial. Some physicians can describe life saving case
histories, while others describe injuries caused by the position. Currently, D.A.N. and
the major dive certifying agencies do not include the Trendelenberg in their suggested
protocols. Rather, they suggest a basic shock position, and if vomiting could be expected,
tilt the patient to one side to prevent aspiration of vomitus.
Practical application of the Trendelenberg Position in the
field presented several problems.
1. Dive Accident patients' spines were injured when objects were shoved under patients'
backs for elevation.
2. Respiratory stress occurred when too radical elevation angles were used, the patient
was kept in the position too long, and/or respirations were not monitored before or during
Trendelenberg positioning. Remember that the position puts pressure on the diaphragm as
well as on the cardiopulmonary system.
3. Cerebral edema occured because of too radical elevations and/or too long durations.
4. The adapted left side tilt could cause shunting of micronuclei bubbles from the right
to left atria if the patient had a patent foramen ovale. (patent = open, foramen = opening
between two chambers, ovale = window.) The foramen ovale is the passage blood takes in
fetuses, as fetuses do not yet have functioning lungs. The foramen ovale is supposed to
seal during birth, forcing all blood from the right atrium to the right ventricle to the
lungs, where among other things, micronuclei bubbles are filtered out of the blood before
it returns to the left side of the heart. The result of this shunting could be additional
gas emboli on the arterial side.
For these reasons, as well as for a disagreement regarding the
benefits of the Trendelenberg position, the position is no longer currently recommended in
the pre-hospital care of DCI patients.