The Following are excerpts from the Field Neurological Guide and
Workbook by Andrea Zaferes and Walt
In Part I of the Field Neurological Examination (FNE) we discussed why and when
to perform the examination. In Part II we will discuss the first steps that take place
before or during the FNE. There are several steps in the decision making and first aid
process, begining with dive accident risk factors.
- There are three main values for understanding dive accident causes and
* early accident recognition
* a better understanding of dive accident physiology, first aid and treatment
* and most importantly, accident prevention
Learn about risk factors for use in the potential patient interview to help
determine whether the possibility of a gas bubble injury exists and what types are most
likely. Record the findings for EMS personnel to give to the receiving hospital and
hyperbaric facility physician.
Think of each risk factor as a red flag. If one or more risk factors are observed before,
during and/or after diving, picture the red flag(s) on the diver's head and be very
watchful of the diver. If the diver surfaces with such a red flag, the diver should be
told about these risk factors and should be monitored for possible Decompression illness
For example, you observe a diver on the boat enroute to the
flag #1: she appears unusually fatigued.
flag #2:. casual conversation elicits the
information that she spent the night partying after three dives in a 10 hour period.
flag #3: she does not appear to drink any
fluid, and when you offer her water she declines saying, "no thanks, I'm a bit
flag #4: you noticed that on at least two
occasions, she descended 10-15 feet below the planned depth of 100'.
flag #5: she was the first one in the water
and the last one out (she said she felt less like vomiting when underwater)
flag #6: she did not do a safety hang
This diver with five DCS risk factor flags should be 'casually' observed and conversed
with after the dive to discover any physical or behavioral signs as quickly as possible.
If one or more potential signs do seem to present, the person in charge such as a dive
leader or boat captain should be quietly notified. Find out if she is willing to have a
FNE performed in an area with privacy. Explain to her the value of a FNE. Explain that you
are trained (if that is true) to perform an FNE. If signs are discovered during the
explain them to her, and explain that she should accept first aid oxygen. Activate EMS.
Monitor and communicate with the patient.
Continue with the rest of the FNE or if the first one was finished, perform a second FNE
in 10-15 minutes and record any findings. If the s/s appear alleviated at this time, or
during a later FNE, explain to her that such an occurrence further indicates the
possibility that she is experiencing some type of DCI problem. This is important, because
sometimes both rescuers and patients think that s/s alleviation indicates there was no DCI
problem or that the problem is now resolved. If she says she feels better, tell her
"great, I'm very happy to hear you feel better. It probably means the oxygen is
working so you definitely need to be examined by a hyperbaric physician."
The red flag risk factors should be recorded and presented with the FNE findings and
administered first aid, to arriving EMS to take back to the hospital. DAN's emergency
telephone number should be at the top of the paper.
Here is an additional example of how to use risk factors to
recognize accidents as quickly as possible.
FLAG #1: a diver appears to have major
problems equalizing and is rising up and down the descent line while simultaneously
performing strenuous-looking Valsalva maneuvers. Upon closer examination you notice that
he makes several rapid 8-9 feet rises while performing Valsalva maneuvers.
You approach and stop his ascent. Take his hand away from his nose and signal him to
breathe in and out as you gently guide his ascent a few feet. Stop him, ask him to attempt
to gently equalize, and ask if his ears are okay. You can tell him that he needs to be
more gentle by demonstrating a gentle and then a simulated, exaggerated Valsalva maneuver,
while indicating the second method is bad and the first method is okay. If his ears are
not okay, have him breathe normally while rising a few feet, and repeat the process.
This diver should be watched during the dive by the leader to notice any presentation of
signs or difficulties. After the dive, the diver should be watched and someone should
explain to him that he was making ten foot breath hold ascents while simultaneously
creating tension in his lungs, upper airways and eustacian tubes. Explain that he should
breath normally whenever ascending, even just a few feet.
If any potential signs are observed and/or if the diver complains of pain, numbness,
tingling, disorientation, confusion, ...etc. begin the process of gaining permission to
perform a FNE, oxygen administration and activation of EMS as dictated.
Without such a risk factor red flag system, this diver might have been allowed to go home
or leave the area. He might have waited hours or even days before reporting a problem to
DAN or a local hospital. The problem might never have been reported and treated, and the
diver would possibly have to live with permanent neurological damage. Or worse, the diver
might have experienced a worse lungoverexpansion injury. underwater resulting in a
The next question is what are the risk factors to look for and ask the diver and possible
witnesses about? Let us examine lung overpressurization injuries risk factors to give you
an idea. Begin by taking out a piece of paper and making a list of all you can think of.
The next step is to read the risk factors below. Pick out which ones you had not thought
about and be sure to share the information with other divers. Then pick out the factors on
your list that are not on this list, and send them to us so we can pass the information.
LUNG OVERPRESSURIZATION INJURIES
Arterial Gas Embolism, Pneumothorax, Mediastinal Emphysema and Subcutaneous Emphysema.
Holding ones breath for whatever reason during an ascent in the water column on
scuba can result in a lung overpressurization injury. A 3-4 foot (approx. 1 m.) or 1.7 psi
pressure differential rise in the water column with full lungs could cause perforations in
alveoli or shunting of air through overexpanded alveoli, and an ensuing overpressurization
As you study the risk factors below keep in mind that 1 pint of gas = 1 lb of buoyancy. So
a 4 pint (2 L) inhalation to clear a mask will have the same result as dropping 4 lbs of
lead off the weight belt. Therefore, divers not skilled in breathing normally on scuba or
performing safe buoyancy control techniques, are at greater risk of making breath hold
Risk factors and causes of lung overpressurization injuries
Not continuously breathing during an ascent or rise
Ascending while coughing, belching, or vomiting
Ascending while equalizing with such breath holding techniques as the Valsalva
maneuver and swallowing.
Poor buoyancy control techniques, including using
inhalations to rise, overweighting and subsequent large volume of air in the buoyancy
compensator underwater, and inflation of the buoyancy compensator to assist with ascents.
Too rapid an ascent (>60 fpm)*
The 1992 and 1993 DAN Accident Reports, reported over 50%
of AGE patients admitting to rapid ascents.
Diving with a cold or respiratory disorder, including bronchitis, asthma,
chronic obstructive pulmonary disorder (COPD), flu,emphysema, allergies, spontaneous
pneumothorax history, etc.
The 1987-1992 DAN Accident Reports showed a range of 20% (1990) to 38% (1987) DCI victims
admitted having current health problems while diving. A range of 47.7% (1992) to 54%
(1991) admitted to having previous health problems. Unfortunately there is no data
demonstrating what percentages of divers without DCI who had current or past health
problems, so few inferences can be made from this data. Hopefully such control data will
be available in the future though.
Hypoventilation or exerted breathing during ascent
The 1991 & 1992 DAN Accident Reports found 58% to 61%
DCI victims reporting that strenuous dives or exercise took place during the day of
injury. Again, there is no control data, so few inferences can be made.
Unconscious breath holding during underwater photography, spearfishing and
Aspirating water and rising with a larangyopasm (trachea
Holding too tightly onto the ascent/descent or anchor line during rough water
conditions while taking deep inhalations, coughing, belching, etc.
Using a drysuit as a buoyancy compensator, especially when
overweighted, can result in accidental, uncontrolled and very rapid ascents that
typically take the diver by surprise and therefore are likely to
involve a degree of breath holding. Such ascents have
been known to take a diver waist high out of the water when reaching the surface. If the
diver is upside down during the ascent, breatholding is even more likely as many
regulators breathe wet when upside down causing aspiration of water and choking.
Exertion, such as lifting a heavy object, can involve taking and holding a large
breath. Weight lifters who are trained to exhale upon exertion will be at less risk of
Improper lift bag techniques can result in the diver being
carried by a lifting device in a rapid, uncontrolled ascent. For example, using the
buoyancy compensator or drysuit as a lift bag, increases the risk of rapid, uncontrolled
ascents. Also, if the diver's regulator, octopus or BC power inflator, is used as the lift
bag filler device it could be caught on the lift bag resulting in a rapid, uncontrolled
Improper training and practice resulting in panic and bolting to the surface
when a mask floods, regulator freeflows, regulator second stage mouthpiece disconnects
from second stage, and the classic "air is used up while underwater" emergency
Buoyancy compensator device freeflowing, and accidental
loss of weight belt underwater can result in rapid, uncontrolled ascents with the surprise
element increasing the chance of breath holding.
Purposeful or accidental skip breathing, apnea are risk factors. Check for a
hypercapnia headache as an indicator.
Using the buoyancy compensator device to rise to the
surface is a very unsafe technique, most often performed by overweighted divers and/or
divers performing improper rescue techniques.
Alcohol, recreational drugs, and some medications could cause decreased mental
status that could perhaps result in too rapid ascents, poor buoyancy control, and/or
The act of attempting to catch and secure a diver bolting
to the surface could involve a reflexive large inhalation and breath hold. Rescuers
should be taught how to simultaneously exhale and reach, to avoid an instinctive
inhale-and-reach maneuver. The exhalation will also serve to decrease the ascent rate as
the rescuer will be less buoyant with empty lungs.
*too rapid ascents: According to Boyle's Law, pressure changes and
resulting gas volume changes are greatest at shallow depths. Therefore rapid and/or
uncontrolled ascents are most dangerous in the first 33 feet of depth.
There are several methods to employ when trying to
discover whether or not an ascent exceeded maximum limits:
1. check the diver's computer, as many computers will give an indication
that the ascent was too rapid, and will display this in the memory after the dive.
2. ask the diver what method was used for the ascent. There are only two
methods that can result in safe ascent rates. These are, continuously monitoring a depth
gauge and timing device, or ascending hand over hand on a line making sure to count a
minimum of 1 second per foot of ascent. If divers tell you that they "moved slower
than their smallest exhalation bubbles", that no technique in particular was used, or
that they stayed with the other divers in the group, then assume the rate was too rapid.
Ask the diver and witnesses is a safety stop was made. If yes, was it on a line. If not,
why not. An important function of safety stops, hangs, is to slow the ascent rate in the
critical shallow depths.
3. Interview witnesses. If the diver was not observed monitoring gauges
and a timing device, or using the hand over hand method up a line, then assume the ascent
was too rapid.
Problems commonly associated with uncontrolled bolts to the surface from depth include:
* mask flooding,
* regulator problems such as difficult breathing, free flowing or wet breathing,
* inability to retrieve a regulator
*out-of-air or low on air situations,
* and heavy, rapid breathing.
Panicked divers often remove their masks and spit out their regulators underwater. If a
diver surfaces in such a state a very large red flag should be put on their head, because
panicked mask removal often results in nose breathing, aspiration, choking and breath
holding. They should be immediately assisted, interviewed and observed.
Question the diver and dive partners to see if any off the above risk factors took place
and record your findings. Negative finding are just as important as positive ones. This is
especially true if you dive in a litigious country and are a dive leader responsible for
Note that the person taking care of the diver-in-need should not be the one questioning
other divers if other persons are available. The diver should not be left alone, nor
should potential witnesses be interviewed in front of the diver to prevent increased
patient stress and witness inaccuracies/untruths. An untrained bystander can be handed the
above list of risk factors and be asked to run through the list with possible witnesses.
In your handling of a potential dive accident patient/victim, it is important to
understand that more than one type of lung overpressurization injury can occur because air
escaping from overexpanded alveoli can go to a variety of places in the body. When in
doubt, always assume and treat for the most serious injury, arterial gas embolism.
Take the time to make a list of risk factors for decompression sickness. If you are an
instructor this is an excellent exercise to do with your advanced and leadership level
students. If you are not in a leadership position, try to do this with your dive buddies.
If you would like a copy of our list for comparison just write or
Lifeguard Systems, P.O. Box 548 Hurley,
NY,12443...USA... tel/fax (845) 331-3383