It has
been said that medicine is both a science and an art. Nowhere
is this more true then when it comes to anesthesia. The science
is the hard facts regarding what we know about the anesthetic
drug’s actions and effects. The art is using these drugs in a
way that is both safe and effective.
Veterinarians have numerous anesthetic drugs at their disposal.
Each of these can be used alone or combined with other drugs in
seemingly countless ways to sedate and anesthetize our patients.
This gets further complicated because each drug has a dose
“range” and different levels of sedation can be reached within
this range. Of course each drug also has potential side effects
like respiratory depression or vomiting. Furthermore, depending
on the drug, results may vary between species (cats vs. dogs vs.
birds, etc), breed, age (puppy/kitten vs. senior), body
condition (underweight vs. overweight), and illness. It will
even vary between individuals. There are no studies that can
take into account all of these variables, nor can we predict
exact outcomes in every circumstance. Thus, anesthesia will
never be “risk-free”. So that’s the bad news!
The really
good news is this: when done well, anesthesia is very safe.
Here’s why:
Both the
inhaled and injectable anesthetic drugs available today are much
safer than those used in the past. Additionally, anesthesia is a
board certified specialty in veterinary medicine and the subject
receives lots of attention. There are a myriad of books and
peer-reviewed studies on these drugs and drug combination
protocols along with lectures at every conference, articles in
all the profession’s magazines, and on-line discussions. The
volume of material is enormous. What is really new though is
the development of anesthetic protocols that take into account
pain management at the same time. These in fact, are really two
sides of the same coin. Certain anesthetic agents have pain
prevention properties and certain pain medications have
anesthetic properties. By using combinations of these drugs and
by focusing on pain prevention prior to and during
anesthesia, we can use lower doses of drugs which minimize
the potential for adverse effects.
Recent
work in this field has taught us several broad concepts in
regards to pain prevention. The first is the importance of “pre-emptive
analgesia”. This is when we give the patient analgesic
agents PRIOR to the onset of pain (i.e. prior to surgery). This
serves to block stimulation of pain receptors and the “wind-up
phenomenon”, both of which can lead to more intense
post-operative pain. The “wind-up phenomenon” is when
nerve fibers start to overreact to even mild discomfort making
the sensation of pain much worse. The second is the importance
of “multimodal analgesia”. Here we use multiple drugs
that act to prevent/treat pain in different ways to provide
better, overall analgesia. The third is probably the most
important: if it would be painful to a person, assume
it is painful for the animal and act to
prevent/treat pain accordingly.
Other ways
we make anesthesia safe is by standardizing our routine
protocols. That is, having set regimes that are used over and
over in a consistent manner so that anesthetic inductions (i.e.
getting the pet “under” anesthesia), maintenance, and recoveries
are as predictable as possible. Thus, any deviation from this is
noticed right away so intervention can proceed immediately.
These protocols are not however set in stone so that they can be
tailored to the individual if appropriate.
Of
critical importance is monitoring. At Merrimack Veterinary
Hospital we have state of the art monitoring equipment. We can
measure ventilation, body temperature, heart and respiratory
rates, oxygen saturation using pulse oximeters, carbon dioxide
levels, blood pressure using Doppler and automated oscillometric
devices, and heart rhythm using EKG.
Anesthesia
is made safer still because we place intravenous catheters in
all of our cat/dog patients and when possible, exotic patients,
for all anesthetic procedures lasting more than 10-15 minutes.
We use these catheters for intravenous fluid support to keep
internal organs well hydrated and to maintain blood pressure.
If necessary, a catheter also gives us rapid vein access in case
of an emergency.
Furthermore, all patients undergoing anesthesia lasting more
than just a couple minutes (some exotics are necessary
exceptions to this) are intubated with an endotracheal tube.
This is a tube that goes down the trachea which keeps their
airway open and clear. It also provides us with the ability to
immediately breathe for the patient if necessary. We also work
very hard to maintain body temperature during anesthesia by
using intravenous fluid heaters, warm water blankets,
circulating warm air blankets, warm water bottles/bags, lots of
blankets, and even baby socks on their feet. Keep in mind too
that we have lots of practice using these drugs on patients with
all the variables described above.
Finally and most importantly, we care.
We want to improve the quality of your pet’s life. We want to
discover and solve their health problem. We want you and your
pet to have as positive an experience in this process as
possible.
Regarding
anesthesia there are a couple of general recommendations to keep
in mind:
a) The
more data your veterinarian has on your pet prior to
anesthesia, the more likely he/she can modify the anesthetic
protocol to best meet your pet’s needs. At a minimum, a
baseline
(“bare bones”) profile is necessary but a more thorough profile
that includes a larger
blood and urine database is much
preferred. The latter is usually done at least several days in
advance of the procedure.
b) Never
convince your veterinarian to use an anesthetic protocol they
are unfamiliar or uncomfortable with because you are under the
impression that it is best for the breed. The most commonly
used anesthetics today are not breed specific or
unsafe for certain breeds. This is a common
misconception. The safest anesthetic protocol is one your
veterinarian and nursing staff are familiar with, regardless of
what drugs are being used.
c) If
a procedure like a dentistry or mass removal needs to be done,
don’t wait until the problem gets worse. The risks associated
with anesthesia increase as the duration of the procedure
increases. If you wait until your pet’s teeth are falling out,
the amount of work to do under anesthesia is considerably more
time consuming than if you had done prophylactic (preventative)
dentistry years before that. Also, if you wait until the lump
goes from being small to large, surgery time may go from being
10 minutes to 60 minutes. Not only does this raise the cost of
the procedure substantially, the longer anesthesia time
increases the risks for your pet as well.
d) Fast
recoveries are not always better recoveries. Sometimes your
veterinarian will use anesthetic protocols that purposely keep
your animal heavily sedated for many hours after an invasive
procedure like a mass removal, declawing, or spay. The purpose
of this is to minimize pain, anxiety, and confusion on
recovery. Many hospitals like ours which are not staffed
overnight prefer to send even moderately sedated animals home
for the evening. They then can be monitored by their owners
rather than having them unsupervised overnight at the hospital.
As a result, owners take their animals home in a more sedate
state than if they took them home the following day. Taking one
or two days to fully recover from a procedure is usually normal.
It doesn’t mean they are having a reaction to the anesthesia.
e) Don’t
deny your elderly pet a procedure that could improve the quality
of their life out of your fear of anesthesia. Anesthesia can be
safe for even very elderly pets if the proper diagnostics are
done beforehand and you take a proactive (i.e. preventive)
approach as opposed to waiting until your pet’s health is even
further compromised.
While we are
working hard at this time, remember that you know your pet best.
Communicate with us if you think your pet is uncomfortable so we
can work with you to make modifications to their treatment plan.
Our goal is to help you keep your pet as comfortable as possible
for as long as possible. Please do not hesitate to call
the hospital if you have additional questions regarding
anesthesia or pain management.
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