One of the unpleasant aspects
of intensive care treatment is that,
there's a reasonably high mortality rate
in the intensive care unit. And there
needs to be a way of determining
brain death. We have very sophisticated
means by which we can
keep the heart functioning and so,
pure heart death is now not
looked upon as the only means by which
we determine death. But each country has
its own legal criteria for determining
of death or NDD. And I've only mentioned the Canadian
criteria here, you need to check your own
country and make sure your criteria
are understood. So in Canada,
the minimal clinical criteria for neurologic
determination of death are an Established Etiology,
so you have to know what's causing the problem
and be able to say that that particular
etiology is capable of causing brain death.
Deep Unresponsive Coma with bilateral
absence of motor responses, excluding spinal
reflexes, so some reflexes will remain
but no response to pain or position sense,
or any of the usual things that one
responds to when normal. There have to be
absent brain stem reflexes. So that may be
response to corneal stimulation,
loss of gag reflex,
loss of cough reflex. So the corneal
response goes both eyes.
Pupillary responses to light, so the pupil changing
size according to different levels of light.
The vestibulo-ocular reflex can be assessed by putting cold water into one ear canal.
This should exhibit a horizontal nystagmus away from water filled ear.
If there is no nystagmus visulized by the examiner, the reflex is not intact.
An apnea test is done.
The patient is discontinued
from the ventilator, but this can only
occur in a situation where there are
no muscle relaxants on board and where there is
virtually no narcotic on board. You turn off
the ventilator and you give the patient a period of time, usually
between, usually around 3 minutes to see if they make any
breathing effort. And then there has to be
absent confounding factors as I've indicated.
So, sedation, deep sedation, muscle relaxation,
heavy use of narcotics can't be in place
at the time that one determines
neurologic death. So at the time
of assessment of NDD, the following confounding
factors preclude the clinical diagnosis.
So if any of these things are
actually in place, you cannot
legally, at least in Canada, make a neurological
determination of death. So there's
unresuscitated shock, or if temperature
is low, below 34 degrees
and it's a bit of a joke, but it's
a legal requirement, that you cannot
be cold and die, you must be warm and die.
Severe metabolic disorders capable
of causing a reversible coma must be
excluded. Severe metabolic
disorders including glucose-electrolyte
and unusual electrolytes such as phosphate,
calcium, magnesium, all need to be checked and it has
to be determined that they are at normal levels.
There has to be an examination to make sure that
there aren't inborn errors of metabolism that
might mimic death or coma.
And you have to make sure
that you're absolutely convinced
that everything that
could mimic coma or death has been eliminated
before you can make the neurologic
determination of death. So, certainly
things like drug intoxication,
alcohol, barbiturates have to be absent at the time
you make this determination. So,
in summary, in this lecture we've discussed the intensive
care unit, the various forms of intensive care
unit that are present in our society now.
We've talked about the training required
to become an intensive care physician and the special
skills that nurses require to work in
intensive care. We've talked about some of the diagnoses
that are critical in the intensive care unit.
And some of the equipment that's used
to try to support patients in the ICU.
And finally, we talked about the neurologic
determination of death, which is a legal definition
of death, and is determined by individuals'
countries, and varies from one place to another,
a little bit, not a lot, but a little bit. So it's important that
you understand your own country's neurologic
definition of death.