Initial Hazard Analysis

Initial Hazard Analysis
REVISION 4 (Final): Revised 4/17/2006
BIOE 1160/1161: Senior Design
Calano, Kumar, McNeal, Odle
The device to be developed is a neck brace specifically for patients suffering from
neuromuscular degenerative diseases, namely Amyotrophic Lateral Sclerosis (ALS). There are a
few potential hazards that may arise while a patient uses this device. These hazards include
suffocation, skin irritation, overheating, difficulty swallowing, and neck soreness and pain. Once
these hazards were identified, the cause and severity of each hazard was identified as well and
each hazard was assigned an initial hazard score.
1. Suffocation: After meeting with representatives from the Pittsburgh ALS Association, it was
learned that if the neck brace collar is too soft, the patient’s head can sink down into brace. The
brace may then cover the patient’s mouth and possibly also their nose causing difficult breathing.
Sometimes patients were found slumped over and their brace had cut off their air circulation,
causing suffocation. If left like this for too long, the patient can die. Therefore, it was determined
that suffocation be deemed a highly severe hazard. Suffocation can also be a concern for larger
patients because the neck brace may not fit them properly.
2. Skin Irritation: Once ALS patients have progressed into the stage of the disease where they
can no longer hold their neck up on their own, they must wear a neck brace. Many patients wear
their brace for many hours during the day and sometimes even when they are in the shower or
sleeping. During this extended period of wear, the neck brace has constant contact with their
skin and may cause skin irritation. Skin breakdown was deemed a medium severity risk since it
would not cause life threatening harm to the patient. Skin breakdown is painful, but inevitable
since the brace is worn frequently. Patients do have the option of taking the brace off, but the
comfort they gain by decreasing skin irritation is balanced by a decrease in neck support.
3. Overheating: ALS patients have limited options when it comes to choosing a neck brace.
There are two main neck brace types: the “closed” neck brace with material contacting the neck
around the entire circumference, and a brace with an “open” neck area which may provide slightly
less support but more air contact with the skin. Patients are more likely to choose the brace with
the exposed neck because the soft collared brace causes them to overheat, since there is no
ventilation. Although overheating is a concern, this risk was considered low severity because the
harm to the individual is not as severe as the other hazard types.
4. Difficulty swallowing: If an ALS patient’s chin is too high or there is a lot of pressure on the
neck area, the patient will have difficulty swallowing. Also, the most current braces are not
customized for the varying neck girth of each patient causing larger patients have problems with
pressure on their neck area. Neck braces are also not usually customized for height. Shorter
patients have problems with their chin being too high. This was given a medium risk because the
patients can take their brace off to eat or readjust the positioning of the brace around their chin for
a short period of time while eating.
5. Neck soreness/pain: Patients who suffer from ALS already encounter muscle soreness and
pain. In addition, they can suffer from additional neck soreness and pain if the brace is improperly
positioned on their neck, especially if height and weight are issues for the patient. Since this can
be remedied by readjusting the brace, this hazard was given a low severity.
After identifying the hazards and the severity, the probability of each hazard occurring
based on its cause was considered as well as the level of risk involved. Risks were measured on
a scale of 1-4, with 1 being an intolerable risk and 4 being a negligible risk. A risk ranking of 2 is
for any hazard that was undesirable. An undesirable risk was defined as tolerable only if
reduction is impractical or if the costs were gross. A risk ranking of 3 was considered tolerable.
A risk was defined as tolerable if the cost (both monetary and cost of decreased functionality) of
the risk reduction would exceed the improvement to be gained.
Probability of Harm Due to Cause:
 The probability of the soft collared brace causing suffocation was low, since it
does not occur that often. This usually occurs after a long time of usage, and not
when the patient initially puts the brace on. The probability of improper fitting
causing suffocation was low because it can be remedied by readjusting the brace
on the patient. However, both the improper fitting and the collar being too soft
were ranked 1 because they both would be intolerable to the patient if either
were to occur.
 Skin irritation caused the rubbing of the collar on the skin has a medium
probability of causing harm. This risk was ranked a 3 because it only causes
slight discomfort and will only occur after long periods of use. Overheating has a
low probability of causing harm since the neck brace has an open design. It is a
negligible risk because the brace can be taken off if the person gets too hot.
Also, overheating is less of a concern outside of warm summer months.
 Difficulty swallowing due to the patient’s chin being too high has a low probability
of causing harm since the brace can be readjusted or taken off for the person to
eat. It has a low probability of occurring as well. It was given a rank of 2
because it would be uncomfortable for the patient. Difficulty swallowing due to
pressure on the neck area has a low probability of causing harm because it is
likely to happen in the open design. It was ranked with a risk factor of 2 because
the resulting discomfort would most likely cause the patient to remove the neck
brace and defeat its functional purpose.
 Neck soreness and pain due to improper positioning has a medium probability of
causing harm. This is because it is likely to happen if the brace is not put on
correctly. It was given a risk ranking of 3 because it has low severity, but a
medium probability of occurring.
Design Controls
To improve the current neck brace designs, the methods of control for each hazard were
assessed. Control measures were adopted for each hazard based on the methods of control.
Suffocation due to the collar being too soft is a design control for which the control measure
adopted was to choose a firm yet comfortable material. Suffocation due to improper fitting is a
process problem since the patient is the one who puts the brace on improperly. The control
measure adopted was to design the new brace to be girth adjustable to enable a better fit. Skin
irritation due to the collar rubbing against the skin is a design issue. The material the brace is
made out of may cause or increase the irritation. The control measure would be to make the
brace out of a hypoallergenic or non abrasive material to prevent skin breakdown. Overheating
due to a lack of ventilation is a design issue because the current closed designed braces
completely covers the neck. The control measure would be to use a breathable material to allow
more ventilation or create a neck brace with an open design allowing the neck area to be
exposed to air. Difficulty swallowing due to the chin being too high is both a design and process
issue. It is a design issue because at times the size of the neck brace is not appropriate and it is
not possible to position the patient’s chin at a comfortable height. It becomes a process issue
when the patient does not position his or her chin correctly on an appropriate brace. The control
measure that would remedy both methods of control would be to make the brace height
adjustable or to offer an array of sizes. Difficulty swallowing due to pressure on the neck area is
a design issue because the brace itself would be putting extra pressure on the patient if he or she
is overweight. The control measure would be to design an open brace or make the brace girth
adjustable. If the brace is open, the weight of the brace is decreased because there is less
material, so the brace places less pressure on the patient’s neck. If the brace is girth adjustable,
larger patients will have a benefit from a fit that better supports their weight. Neck soreness or
pain due to improper positioning is a process issue since it is the patient who puts the brace on
wrong, causing themselves more pain. The control measure would be to make the brace girth
adjustable and available in different heights so the best fit is ensured.
New probabilities/risk
New probabilities and risk rankings were assessed for each control measure.
The probability of suffocation due to the collar being made from a non collapsible material
is very low because the brace is less likely to cause the patient’s neck to sink into the
brace. It was then given a risk ranking of 4 because suffocation would then be a
negligible concern. The probability of suffocation occurring in an open design brace is
also low. This is because there is no material to cover the patient’s mouth and/or nose
even if the head should happen to fall down into the collar. The ranking of 4 stands.
Skin irritation due to the brace being made from a non abrasive or a hypoallergenic
material is low. This is because it is likely that some skin irritation will occur despite
constant contact of the brace with the patient’s skin. Therefore, it was given a risk
ranking of 3. The probability of overheating occurring if the brace has either an open
design and/or is made from a more breathable material is low. It was given a risk ranking
of 4 because overheating does not occur often, and it would occur even less if the control
measures were taken into account.
Difficulty swallowing is less likely to occur with a variety of heights available to the user.
Custom height adjustability can also be incorporated by custom making the chin cup.
Swallowing would become less of an issue because the chin would be at the right height
for all patients. Since the probability of this occurring is very low, it was ranked with a risk
factor of 4. The probability of having difficulty swallowing with a brace that has an open
design or is girth adjustable is very low. This is because less pressure would be placed
on the neck. It was given a risk ranking of 4 since it was less likely to occur.
Neck soreness and pain with girth adjustable brace that has a variety of heights and
custom height adjustability available is very unlikely to occur. Both control measures
ensure the best fit for each patient because the fit could be more customized. Therefore,
it was given a risk ranking of 4.
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