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Authored by:
Laura McLain Madsen DVM
Veterinarians anesthetize animals
on a daily basis. At least once
per week in any clinic, a pet owner expresses concern about
anesthesia: Is it safe? Will my pet survive the procedure?
Modern anesthesia is very safe.
The risk of a pet dying under anesthesia is less than 1%. The
rare patients that are lost under anesthesia are generally
emergency surgeries, when the patient's condition is extremely
critical. The risk of a pet dying under anesthesia while
undergoing a routine spay, neuter, dental or mass removal is
extremely low, but this risk can be affected by the anesthetic
drugs used and the monitoring of the patient.
Can
you imagine an anesthesiologist in a human hospital using
ether or chloroform in the 21st century?
Of course not. But, unfortunately (and surprisingly),
there
are no standards of care for veterinary anesthesia, and some
clinics are still using out-of-date techniques. Here is a
list of questions to ask your veterinarian the next time your
pet is scheduled for an anesthetic event:
1) Is pre-anesthetic blood work
run? All patients, not just the
old or sick, should have basic pre-anesthetic blood tests
performed checking the blood sugar, kidney values, and red
blood cell count. Many animals will require more extensive
pre-anesthetic blood work. Even in animals under one year
old, blood work will occasionally detect abnormalities that
could affect anesthesia.
2) Are intravenous fluids
administered during anesthesia?
Many drugs used for general anesthesia tend to cause blood
pressure to decrease. Intravenous fluids will combat this
decrease. In addition, if there are any adverse reactions
under anesthesia, an intravenous catheter allows immediate
administration of emergency drugs.
3) Is the pet's body temperature
maintained during and after anesthesia? All animals, especially cats and small
dogs, lose a lot of body heat under anesthesia. The resulting
hypothermia can slow the anesthetic recovery. Anesthetized
pets should be placed on a recirculating warm water pad and/or
under a warm air blanket. Conventional heating pads are risky
because they can cause burns.
4) Is the pet intubated, and what
anesthetic gas is used?
Intubation means that the patient has an endotracheal tube
placed through the mouth and into the trachea, through which
gas anesthetic is administered. The endotracheal tube allows
controlled respirations if the patient is not breathing well
on his or her own, and prevents accidental inhalation of
stomach contents if the pet vomits under anesthesia.
Virtually every surgical procedure done in dogs and cats
requires intubation and gas anesthesia. The modern gas
anesthetics are halothane, isoflurane and sevoflurane.
Methoxyflurane is out-of-date.
a. What pain control is used?
Surgery hurts! It doesn't matter if the patient is a human, a
dog, or a guinea pig. Analgesia is the relief of pain, and in
modern anesthetic protocols we strive for pre-emptive
analgesia (blocking the pain pathways before the painful
procedure starts), and balanced anesthesia (trying to block
the pain pathways from as many directions as possible).
5) What monitoring techniques are
used? It is critical to monitor
the patient's vitals while under anesthesia to ensure that the
respiratory and cardiovascular systems are functioning well,
and to ensure that the patient is not under too lightly or too
deeply. Most important is that someone besides the surgeon
(who is occupied) is monitoring the heart rate, respiratory
rate, and anesthetic depth.
Additional commonly used
monitoring techniques include:
- An electrocardiogram (EKG) to
monitor the heart rhythm for arrhythmias.
- A pulse oximeter to monitor the
percentage oxygenation of the blood, which should be close
to 100%.
- A machine to monitor the blood
pressure.
- A machine (apnea monitor or
capnograph) to monitor the respiratory rate and carbon
dioxide level.
Another concern many pet owners
have is the cost of anesthesia:
Why is it so expensive? Why does
Dr. X charge $300 for a dental while Dr. Y down the street
only charges $100? As you can see, modern anesthesia involves
a lot of equipment and expertise, and this unfortunately costs
money. Cutting corners by not
intubating patients, not keeping patients warm, or skimping on
pain medications and monitoring can save money, but the price
is decreased comfort and safety for your pet.
by Laura McLain Madsen, DVM
Date Published: 1/11/2004 5:41:00
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