Peri Anesthetic Hypothermia Peri Anesthesia Hypothermia occurs in up to 80 of anesthetized cats and dogs PeriAnesthetic Hypothermia Hypothermia is associated with P rolonged healing ID: 698832
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Slide1
Patient Warming
The problem – The solution Slide2
Peri
-Anesthetic Hypothermia
Peri
-Anesthesia Hypothermia occurs in up to
80%
of anesthetized cats and dogsSlide3
Peri-Anesthetic Hypothermia
Hypothermia is associated
with:Prolonged healing I
ncreased dysrhythmiasIncreased blood lossIncreased infection
P
atient morbidity
Technician/nurse time
Dentistry is the
#3 procedure most likely to end in anesthetic death
50% of anesthetic deaths occur during recovery
Go to
Making Anesthesia Easier
blog post
“
Hypothermia and the Veterinary Dental Patient”Slide4
Peri-Anesthetic Hypothermia
A review of the survival rates of Yorkshire Terriers after portosystemic shunt surgery showed the single most prognostic indicator for survival was postoperative temperature.Slide5
Peri-Anesthetic Hypothermia
Contributors:
Small body sizeDrug-altered peripheral perfusion
Intubation bypasses the noseBreathing cold gasesRadiated heat loss from skin surfaceOpen body cavitiesWater during dentalsSlide6
Each stage of a procedure presents unique hypothermia challenges…
PremedicationClip and Prep
SurgeryRecoverySlide7
Peri-Anesthesia Hypothermia StudySlide8
During Premedication
Premedication
causes the first signs of hypothermia. Dogs
and cats typically lose 1º
to
2ºF
over 30 to
45 minutes before induction of
anesthesia (blue line).Slide9
During Clip and Prep
The precipitous
, critical
loss of 2º
to
5ºF
body heat occurs
in the first 15 to 30 minutes
after induction: during
clip and prep time (blue line).The patient may lose as much as 7ºF before you ever begin the procedureSlide10
During Surgery
Once the animal is
draped for surgery, heat loss
slows (blue line).Slide11
During Recovery
Warming hypothermic animals recovering from anesthesia is a slow and
labor-intensive process, often taking more than 1 to 2 hoursSlide12
Traditional prevention ineffective
Prevention and treatment of hypothermia has focused on body
surface warming and has proven to be ineffective
(blue line)…And sometimes dangerousSlide13
Common devices can cause harm
The
margin of safety to prevent significant thermal injury is surprisingly narrow.
Skin can burn from as little as 115ºF of constant
surface heat for one hour
. (Hot tap water is warmer than 115ºF)
W
arm water jugs, heated rice or wheat bags, 'on-off
' electric heat
pads, and any other warming device not specifically designed for sedated or anesthetized animals can
cause
severe
burns
. Slide14
Common devices can cause harm
Sedated, anesthetized, and recovering animals
can't move away
from excessive heat.Slide15
Common devices can cause harm
Zelda – February 2017Standard electric heating pad used during dental
Skin changes took several days to manifestHair loss
RednessMoist desquamation Ulceration Progressed over the next weekUnderwent three reconstructive surgeries at referral hospital (WSU)
Died during the third surgery
20 days after dentistrySlide16
Safe and effective warming
Thermostatically
controlled warm air blankets
safely distribute heat evenly and constantly.Slide17
Solving Peri
-Anesthesia HypothermiaIt’s easier to prevent hypothermia than to overcome itSlide18
3-step solution to hypothermia
Pre-warming
Warmed inspired gases
Warm air blanketsSlide19
1. Pre-warmingSlide20
Pre-warming; like pre-oxygenating
Thermal support before anesthesia
prevents the
initial 1o – 2oF drop in body temperature and slows the critical rapid heat
loss immediately following anesthesia
inductionSlide21
Pre-warming
safelyA Warm
Air Blanket System can safely deliver air at a constant 109ºF and
effectively pre-warm caged animals before anesthesia. Slide22
2. Warmed Inspired GasesSlide23
Warm from Within
Patient warming is now as simple as using a
better breathing circuitSlide24
Capture Control at Intubation
Warmed inspired gas allows you to
capture
control of a patient’s body temperature from the moment of intubation, at induction.Slide25
Warmed inspired gases
Rapid heat loss
occurs after induction as an animal is moved during the clip and prep
periodPositioning results in poor surface heat transfer from heated pads or mats.Surface heating is not sufficient
to overcome this stage of hypothermiaSlide26
Warmed gases prevent heat loss
The rapid loss of 2o
– 5oF that occurs during
the clip and prep period can be prevented by delivering warmed inspired anesthetic gases from the moment of intubation.Slide27
Your choice of circuit is importantSlide28
Rebreathing Circle System + / -
Advantages:
Keeps patients warmerRetains moisture
Efficient use of gasVersatile – use with a wide range of patient sizesLower gas flow = lower costLower gas flow = less pollutionLower gas flow = less heat loss
Disadvantages:
Increased resistance
Many parts
Slow % concentration changeSlide29
Non-Rebreathing System + / -
Advantages:
Minimal resistanceFew parts
Rapid % concentration changeDisadvantages:
Patient loses body heat
Patient loses
moisture
Inefficient use if gas
Narrow
range of patient sizesHigher gas flow = higher cost
Higher gas
flow =
more pollution
Higher gas flow = more heat lossSlide30
Overcome the
high cost of NRB circuits
Non-Rebreathing Circuits are expensive to use:They cost more money to use
10 X more oxygen flow than rebreathing circuit10 X more anesthetic gas flow than rebreathing circuitThey cost patient body heatHigh oxygen flow syphons heat from patients
They cost the environment
10 X more anesthetic gas flows into the atmosphereSlide31
Examine hospital policy
When do you use a non-rebreathing circuit?Choose a non-rebreathing circuit for patients weighing less than
?
poundsWhy that number?I’ve seen target weights from 20# to 5#Slide32
For more information
Read Making Anesthesia Easier
blog post:
“Rebreathing or Non-rebreathing?”Go to DarvallVet.com and follow the link to the blogSlide33
3. Warm Air BlanketsSlide34
Warm Air Blanket Systems
Warm air blankets with high surface air flow (designed for humans) are unable to raise the body temperature of hypothermic dogs and cats during anesthesia.
Warm
air blanket systems designed with a porous patient contact surface permit the hair-coat to trap warm air
, holding it close to the patient’s body.Slide35
Warming effectively
Recent
research shows that only the
Darvall warm air blankets can consistently raise body temperature
under anesthesia.
Darvall
Blankets make all warm air blowers work betterSlide36
Peri-Anesthetic Hypothermia
Hypothermia is associated
with:Prolonged healing I
ncreased dysrhythmiasIncreased blood lossIncreased infection
P
atient morbidity
Technician/nurse time
Dentistry is the #3 procedure
most likely to end in anesthetic death
50% of anesthetic deaths occur during recoveryHypothermia is a likely contributor
Go to
Making Anesthesia Easier
blog post
“
Hypothermia and the Veterinary Dental Patient”Slide37
To recap: 3-step solution
Pre-warmingPrevents initial 1
o – 2o
F heat lossWarm inspired gases
Prevents 2
o
– 5
o
F loss during clip and prep
Warm air blanketsPorous blanket / low air flow traps heat, warms animalsSlide38
Thank you for your attentionSlide39
Questions?Slide40
This presentation is provided with support from:
For a copy of this slide deck email Ken Crump
kcrump@darvallvet.com