Transcript MAINTAINING ANESTHESIA

MAINTAINING ANESTHESIA
*Information is primarily found in ch. 5 of
Your surgery textbook on pgs 139, 140-145,
169-173
MONITORING
• Involves both _________and __________
• Can be done with or without ___________
VITAL SIGNS
Variables that indicate the response of the
patient’s homeostatic mechanisms to
anesthesia and how well the patient is
maintaining circulatory and respiratory
function during anesthesia
VITAL SIGNS INCLUDE: Heart rate, CRT, mucous
membrane color, pulse strength, blood pressure,
respiration rate, and temperature
MONITORING WITHOUT
INSTRUMENTATION
• YOUR _________, ________, AND ______ ARE
YOUR MOST VALUABLE MONITORING TOOLS!
• Machines WILL fail!
• Only rely on machines to provide you with the values
that you cannot determine on your own
(______________, _____________, _____________,
___________________,
___________________________)
HEART RATE AND RHYTHM
under ANESTHESIA
• DOGS: 60-150 bpm
– REPORT if ________ or ______ bpm in lg dogs
________ or ______ bpm in sm dogs
• CATS: 120-180 bpm
– REPORT if _______ or _______ bpm
• Lower heart rates are commonly observed with
anesthesia due to the effects of the anesthetic
agents.
– Anesthetic drugs can also effect the heart’s rhythm.
OPTIONS FOR CARDIAC
MONITORING
__________________
__________________
_________________________
ESOPHAGEAL STETHOSCOPE
An esophageal stethoscope is a thin, flexible tube that is
attached to a regular stethoscope. Lubrication is applied
to the end of the tube which is placed in the oral cavity and
down the esophagus until a heartbeat is heard.
This allows a person to listen to the heart on an animal that is
draped in for a surgical procedure
Always assess heart rate/rhythm along with pulse strength,
CRT, mucous membrane color, and blood pressure if possible
CAPILLARY
REFILL TIME
• The rate of the return to color for mucous membranes
after the application of digital pressure compresses
capillaries and blocks blood flow temporarily
• Provides information about __________________
• A normal CRT does not necessarily indicate
that the patient is normal, however a prolonged
CRT (longer than 2 seconds) means that tissue
perfusion is not adequate
– Possibly due to vasoconstriction, hypotension, hypothermia,
heart failure, shock, or excessive anesthetic depth
MUCOUS MEMBRANE COLOR
• SHOULD BE PINK!
• Look at gingiva – most convenient
– If gums are pigmented, look at the conjunctiva, or
the inner prepuce or vulva
• If pale, there may be blood loss, anemia, or
poor perfusion
• _______________= purple or blue discoloration.
EMERGENCY!
PULSE STRENGTH
• Can be done at the _____________,
_________________-,
_______________________, and
________________________________
• Should be strong and match the heart beat
• Weak pulses may indicate hypotension (low
blood pressure)
– Causes: excessive anesthetic depth, excessive
vasodilation, cardiac insufficiency,
excessive blood loss
BLOOD LOSS
• Can cause complications
such as shock
• One 3x3 gauze =
______ mL of blood
• The actual amount lost
may be more due to clotting
or pooling of blood
• Healthy animal tolerates
~ 13mL/kg blood loss
during surgery
Intra-abdominal blood clot
Intra-abdominal blood pooling
RESPIRATION RATE AND DEPTH
• Can be evaluated by watching the _________
______________ or ____________________
• Normal values while under
anesthesia: ________ bpm
• ____________________ (volume of air inhaled)
decreases with the anesthetic depth
• Shallow breaths can cause the
lung on the down side of the body
to collapse (atelectasis)
RESPIRATION RATE AND DEPTH
Bagging the patient
• Performed when assisted ventilation is necessary to
_____________________________________ , or to
_______________________________
• Closing of the pop off valve and gently squeezing of the reservoir
bag causing the patient’s chest to fill with oxygen/anesthetic gas
HYPERVENTILATION and tachypnea
• HYPERVENTILATION: Increase in
respiratory depth
– (tachypnea = increase in respiratory rate)
• Causes of hyperventilation and tachypnea
– Body’s response to increased CO2 in the
blood
– Underlying pulmonary disease
– Surgical stimulation
– Decrease in anesthetic depth
• Patient is too “light” or waking up
RESPIRATORY RATE AND DEPTH
CONTINUED…
• Normal breaths are smooth and regular, not gasping
or labored
• DO NOT FORGET TO USE YOUR STETHOSCOPE TO
EVALUATE BREATH SOUNDS!
– Should not hear crackles or wheezes
THERMOREGULATION
______________ is the most common
anesthetic problem and has many ways to
be prevented or corrected
Prevent from the
moment the animal is induced.
» The greatest decrease is
within the first 20 minutes.
The following can decrease body
temperature:
Check the patient’s temperature at least every 15-30
minutes if there is not an esophageal or rectal probe
available to do continous monitoring. In between temp
measurements, feel the animal’s extremities.
Several methods to avoid
hypothermia:
Circulating warm water
heating pad
Self-warming surgery table
Fluid line warmer
Bair
Huggers
ALWAYS PLACE A TOWEL
OVER HEAT SOURCES
TO PREVENT BURNS!!!!!!
Do not place animal directly onto
stainless steel table or heating pads!
Also monitor for hyperthermia (especially
post-operatively) which can happen
with some anesthetic agents (opiods,
ketamine).
HEATING PAD BURNS
REFLEXES
Involuntary response to a stimulus
• Indicate depth of anesthesia, but no info
on homeostatic mechanisms
• Most commonly used: palpebral, pupillary
light response, swallowing, pedal
(withdrawal), ear flick, laryngeal
_________________ Reflex
Touch the corner of the eye and the animal
blinks.
This reflex is stimulated by tapping the skin
at the medial or lateral canthus of the
eye or by running the finger along the
eyelashes. This reflex is gradually lost as
anesthetic depth increases.
__________________________ Reflex
Immediate closure of the epiglottis and vocal
cords when the larynx is touched by any
object.
Stimulation of the larynx will cause the animal to
swallow. The stimulation may be from outside,
for example, an attempt to pass an
endotracheal tube or may be internal for
example the presence of secretions at the
larynx. This is a mechanism to prevent
accidental aspiration of fluids into the lungs.
____________________ Reflex
Pull a limb gently, pinch the toe and the
animal will pull back the limb.
The reflex is obtained by firm pressure of
the interdigital skin in the dog and cat
*particularly important in animals
undergoing mask inductions
______________________ Reflex
Shine a light in the eye and the pupil constricts.
The pupillary responses under anesthesia are
heavily influenced by pre-medication.
Species variations exist. There is also variability
in response to different anesthetics. In general,
in un-premedicated patients, the pupil is dilated
in the early excitement phase and then becomes
progressively constricted as surgical anesthesia
occurs. With very deep surgical anesthesia the
pupil begins to dilate again and with entry into
stage IV, with respiratory and cardiac arrest, the
pupil is maximally dilated.
_________________ Reflex
Touch the cornea and the animal blinks. Be careful
not to damage the cornea if this reflex is tested.
This reflex is obtained by gentle palpation
of the lateral aspect of the cornea. This
causes reflex closure of the eyelids.
This reflex is not always reliable in the
dog, particularly if the eyeball is markedly
rotated.
_____________________ REFLEX
Pinnal reflex used in cats.
Gently touch the hair on the inner
surface of the ear and watch the pinna
twitch.
Don’t test too frequently or the reflex will be
inaccurately lost.