Field Neuro 1 Field Neuro II Field Neuro III

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The Following are excerpts from the Field Neurological Guide and Workbook by Andrea Zaferes and Walt "Butch" Hendrick

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.

  1. There are three main values for understanding dive accident causes and risk factors:
    * 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 (DCI).

For example, you observe a diver on the boat enroute to the dive site.
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 nauseous."
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 FNE, 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 fatality.

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.

Arterial Gas Embolism, Pneumothorax, Mediastinal Emphysema and Subcutaneous Emphysema.

Holding one’s 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 injury.

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 ascents.

Risk factors and causes of lung overpressurization injuries include:

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 videography

Aspirating water and rising with a larangyopasm (trachea closed off)

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 injury here.

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 ascent.

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 occurs, etc.

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 breath holding.

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
* overweighting,
*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 the divers..

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 call:

Lifeguard Systems, P.O. Box 548 Hurley, NY,12443...USA...     tel/fax (845) 331-3383



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Copyright 1998 Sortie Publications, Inc.
Last modified: April 08, 2003