Biomedical Engineering Reference
In-Depth Information
failure applies to numerous ethical failures. However, the prefix “mis-” can connote something that is
done “poorly,” i.e., a mistake. It may also mean that an act leads to an accident because the original
expectations were overtaken by events, i.e., a mishap. Medical and engineering codes of ethics include
tenets and principles related to competence, such as only working in one's area of competence or
specialty. Finally, “mis-” can suggest that an act is immoral or ethically impermissible, i.e., a misdeed.
Interestingly, the theological derivation for the word “sin” (Greek:
hamartano
) means that a person has
missed the mark, i.e., the goal of moral goodness and ethical uprightness. That person has sinned or has
behaved immorally by failing to abide by an ethical principle, such as honesty and justice.
Bioethical failures have come about by all three means. The lesson from Santayana is that we must
learn from all of these past failures. Learning must be followed by new thinking and action, including
the need to forsake what has not worked and shift toward what needs to be done.
Engineering failure can be categorized into five types. Whether the failure is deemed unethical is
determined by the type of failure and the circumstances contributing to the failure.
Failure
Type
1:
Mistakes
and
Miscalculations
Engineers have been known from time to time to make mistakes. Their works fail due to their own
miscalculations, such as when parentheses are not closed in computer code, leading to errors in predicting
pharmacokinetic behavior of a drug. Some failures occur when engineers do not correctly estimate the
corrosivity that occurs during sterilization of medical devices (e.g., not properly accounting for fatigue
of materials resulting from high temperature and pressure of autoclave). Such mistakes are completely
avoidable if the physical and biological sciences and mathematics are properly applied. Avoiding such
errors is reflective of engineering competence. Interestingly, such failures are sometimes referred to
as technicalities. After all, how unethical can an omitted parenthesis be? Actually, according to the
reasonable engineer standard it is quite unethical. To paraphrase Norman Augustine, bad technical
decisions
are
unethical.
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Failure
Type
2:
Extraordinary
Natural
Circumstances
Failure can also occur when factors of safety are exceeded due to extraordinary natural occurrences.
Engineers can, with fair accuracy, predict the probability of failure due to biophysical and biochemical
processes, such as metabolism and cellular receptor activity, but “normal” thresholds can be exceeded.
Engineers design for an acceptably low probability of failure - not for 100% safety and zero risk.
However, tolerances and design specifications must be defined as explicitly as possible.
The tolerances and factors of safety have to match the consequences. For example, while a failure
rate of 1% may be acceptable for the general use light bulb, it is grossly inadequate for the light system
(laser) used in medical systems. And, the failure rate of devices may spike up dramatically during an
extreme natural event (e.g., power surges during storms). Equipment failure is but one of the factors
that lead to medical failure.
A recent study,
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for example, identified the reasons for relatively high failure rates associated with
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selective laser trabeculoplasty (SLT) to treat intraocular pressure (IOP) in glaucoma patients. In
this procedure, a very intensely focused beam of light is used to treat the eye's drainage angle (the
