Hello ladies and gentleman.
This is a continuation
of our discussions and lectures on Anesthesia.
In this presentation we are going to talk
about Additional Anesthetic Drugs. And we're going
to spend a little time talking about pain, although
we'll have a much fuller discussion
of the Management of Pain in a future lecture.
So what is Pain? The International Association
for the Study of Pain (IASP),
defines pain as an unpleasant
sensory and emotional experience
associated with actual or potential
tissue damage, or described in terms
of such damage. So, when we talk about pain,
we often talk as if something had been damaged,
even when we don't know that that in fact has happened.
So these are some of the subcategories
that the IASP has defined, and I'm not going
to go through all of these. You can look
them up if you wish, but it's
a very complex, extensive
list of subcategories of pain. And there are
variations in treatment depending upon
which type of pain an individual suffers from.
We're going to talk in more general terms about pain.
So the IASP states that about
30% of humans suffer from
chronic pain at some point in their lives. And chronic
pain is pain that lasts for greater than 3 months.
Some people say greater than 6 months.
They further go on to say that about 7%
of people are completely incapacitated
by chronic pain. It's the most prevalent cause
of disability that we have in healthcare.
Greater cause, greater cost
of disability than cancer
and heart disease combined.
It's universal. It's a human characteristic that
exists in every one of us.
Perception of pain is not modified
by ethnic background, but presentation of pain
is affected by the culture from which you
come. And let me give you an example of this.
I often teach anesthesia residents in Uganda.
And one of the things I noted the first time I went
to Uganda, was how unbelievably stoical
Ugandan people are. They never complained about pain,
they never asked for drugs. The amount
of pain medication given was minuscule.
And I thought this was odd,
because my understanding was that, we all feel pain
the same, it didn't matter what culture we were in. So,
I did a little study where we actually went and saw patients
postoperatively. And we asked them to give them,
to provide a pain score. 0 for nothing,
up to 10 for absolutely excruciating
pain. And what we discovered was what
I expected to discover, is that Ugandans,
like everybody else in the world, have pain and they have
pain at about the same level as everybody else.
But culturally, it's not really acceptable
for them to show pain. Stoicism
is expected. The reality is, they suffer
pain just like the rest of us.
Surgical pain is acute pain. But we must
discuss chronic pain, and we will discuss
chronic pain in a future
series of slides. So pain is
not a benign process. Cardiovascular
and respiratory systems are significantly
affected by the pathophysiology of pain.
There's dramatic adrenergic stimulation.
This is release of Norepinephrine throughout
the body and from the adrenal gland.
Hypercoagulation can occur leading
to disseminated intravascular coagulation.
Heart rate goes up. Cardiac output goes up.
Myocardial oxygen consumption goes up,
which can lead to myocardial ischemia or myocardial
infarction. Pulmonary vital capacity drops
because, particularly if you've had an injury
to your chest or surgery to your chest,
you splint your muscles and you
can't breathe deeply. And this can lead
to alveolar hypoventilation, reduction
in functional residual capacity, atelectasis,
pneumonia, and serious problems
with arterial hypoxemia
throughout the body. Also, pain suppresses
immune function, predisposing
trauma patients particularly, to wound infections
and sepsis. So what are analgesics?