Done by Osama Alfaqeh Types of anesthesia Local Anesthesia Regional Anesthesia Spinal anesthesia injected into the spinal fluid Epidural anesthesia outside ID: 908803
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Slide1
Conduction of anesthesia
Done by
Osama Alfaqeh
Slide2Types
of
anesthesia
Local
Anesthesia
Regional
Anesthesia
Spinal
anesthesia
:
injected into
the
spinal
fluid
Epidural
anesthesia
:
outside
the
spinal
column
{epidural
space}
General Anesthesia :
a reversible
state
of CNS
depression
→ loss of
responses to and
perception
of stimuli.
It
should
provide
adequate
:
Sedation
and
reduction
of
anxiety
• Lack of
awareness and
amnesia
•
Analgesia
Skeletal
muscle
relaxation
•
Suppression
of
undesirable
reflexes
while maintaining
the
patient’s
normal physiological
functions
(
hemodynamic
stability
,
oxygenation
,
ventilation
,
temperature
)
Slide3Slide4Slide5What
is
the “perfect”
anesthetic?
Slide6MODERN ANESTHESIA IS A COMBINATION
OF:
IV
and
inhaled
agents
for induction
and
maintenance
of
anesthesia
-
IV
:
Propofol
,
ketamine
,
Sodium
Thiopental
,
etomidate
,
TIVA
;
total
intravenous Anesthesia propofol
+
Rimefentanil
-
INHALED
:
Sevoflurane
(most
commonly used inhaled agent
/
works
rapidly
and
recovers rapidly)
Muscle relaxants
(e.g.
rocuronium,
vecuronium ,
succinylcholine,
cisatracurium
/
Nimbix
,
atracurium
).
Analgesics
(e.g.
opioid
,
fentanyl
)
Slide7Depth of general anesthesia
produce CNS depression from higher centers toward lower centers to keep life because the vital centers are below
why does drugs affect higher centers before lower centers? How does this work?
In the higher centers we have
multi synaptic pathways with short interneurons resembling a large network, while in the lower centers neurons are long.Drugs will affect multi synaptic short interneurons networks more than they will affect long neurons.
Slide8stages
of general
anesthesia
Analgesia
:
decreased awareness
of pain/
amnesia
without
loss
of
consciousness
work on highest point
of the brain which is the
point of Sensation
by causing analgesia and loss of sensation (mainly pain)
Excitement/ delirium
:
From loss of conscious to beginning of regular respiration
Goal
is
to
move
through this stage as
rapidly
as
possible by giving rapid-acting IV agents before inhalation anesthesia is administered.
Work on :
First (cerebral cortex) remove the Higher Inhibitory Control
excitement
Second (reticular activating center)
loss of consciousness
This stage is more apparent with less specific CNS depressants (ex. Alcohol ).The stage of excitement
everything increases
, skeletal muscle tone, reflexes, heart rate, blood pressure, arrhythmia, respiratory, everything increase.it is not a desired stage, we want to get through it fast so as not to have any complications before the surgery.
Slide9stages
of general
anesthesia
Surgical anesthesia
: Unconsciousness /decreasing eye movement/regular respiration, heart beat and BP
Plane1
:
roving eyeballs(this plane ends when eyeballs become fixed)
Plane2
:
loss of corneal and laryngeal reflexes
Plane3
:
pupil starts dilating with loss of light reflex
Plane4
:
intercostal muscles paralysis shallow abdominal respiration and dilated pupil
Here we have loss of two things
1)Skeletal Muscle Tone
2) Reflexes (so that patient will not have vomiting, cough reflex and laryngospasm
NO aspiration pneumonia)
# The previous three stages are therapeutic pharmacological stages
Slide10stages
of general
anesthesia
Medullary paralysis
(too deep/ overdose ) :
anesthetic crisis
between respiratory arrest and death due to circulatory collapse.
In higher toxic doses of anesthesia the lower vital centers will also be affected.
should not be reached
, and if we approached this stage we must back down before we have depression of the respiratory and vasomotor centers.
But this
makes things harder
when we want to
decide the appropriate dose
of anesthesia, because people are different some may be old some may be young, some may have liver disease
Slide11stages
of general
anesthesia
STAGE I
)
Analgesia)
STAGE II
(Delirium)
STAGE III
(Surgical Anesthesia
)
STAGE IV
(Medullary paralysis)
Shortened or eliminated
by giving IV anesthetics
Ideal stage for surgery
k
Slide12Phases of anesthesia :
1) Induction
Induction
:
period of time
which begins
with the
administration
of
anesthesia to the
development
of
surgical
anesthesia
(induction
time)
It is
usually
done
with
IV
anesthetics
like
propofol
(it
will produce unconsciousness within 30
seconds)
,sodium thiopental, ketamine
and
etomidate
(((
Induction
depends
on
how fast
effective
concentrations
of
the
anesthetic drug reach
the
brain
Onset
of
anaesthesia
is
faster with
intravenous
injection
than with
inhalation, taking about 10–20 seconds
to
induce
total unconsciousness )))
Thiopental sodium is the barbiturate used for IV induction of
anesthesia in cardiac surgery.
It is the only ultra-short-acting
drug that is used for induction.
Slide13Inhalation anesthesia
for
conduction
SEVOFLURANE
is
currently
the
most commonly
used
agent
for
inhalational
induction
because
of
the
rapid
onset
&
recovery from
it
Indications
of inhalation
induction:
Difficult or
no
IV
access
.
Bronchopleural
fistula or
Empyema.
Young
children.
Difficulties and
complications
:
Slow induction of
anesthesia.
Airway obstruction
and
bronchospasm.
Laryngeal
spasm
.
Environmental
pollution.
Advantages over
IV
agents:
The depth
of
anesthesia
can be
rapidly
altered by changing
the
concentration
of
the
drug.
Reversible.
Rapidly
eliminated by
exhalation
.
Slide14Phases of anesthesia :
2) Maintenance
Maintenance :
Sustaining
the state
of
anesthesia
. Mainly
by
inhalation
anesthetics (with
an admixture
of
nitrous
oxide
and halogenated
hydrocarbons)
sevoflurane
has
some
bronchodilatory
effects
that are valuable in preventing
bronchospasm
Inhalational
agents: Sevoflurane, Isoflurane but also Halothane in
a
mixture of nitrous oxide 70% in oxygen
IV
anesthetic
agents.
propofol
IV opioids
(Fentanyl, Alfentanil,
Remifentanil)
(Alone or
Combinations)
For special
conditions
:
Ephedrine
–
increase
BP
Atropine
–
increase
HR
Adrenaline
–
in
case
of Asystole
Slide15Phases of anesthesia :
3)
RECOVERY
This
is
the
time
from
the
discontinuation of anesthetic until consciousness and
reflexes
return
.
The
patient
is
monitored until return
of
normal
physiologic
functions.
It
usually
takes
about
45
minutes
to
an
hour
to recover
completely
from
anesthesia
.
In
some cases, this
period may
be
longer
depending
on medications
given
during or
after
surgery.
recovery ,
depends on how
fast the
anesthetic drug diffuses
from the
brain
Slide16IV
ANESTHETICS
Advantages:
Rapid
onset.
Depression
of
pharyngeal
reflexes allows early
insertion
of
Laryngeal
mask
airway
(LMA).
Anti-emetic
and
anti-convulsive
properties.
Disadvantages:
Venous access
required.
Risk of
hypotension.
Apnea
common.
Loss of
airway control.
Anaphylaxis.
Slide17Inhalation anesthetics
Advantages:
Avoids
venopuncture
.
Respiration is
maintained
Slow
loss of protective
reflexes.
End-tidal
concentration
can be
measured.
The
depth of anesthesia
can be
rapidly
altered
by
changing
the
concentration of
the
drug.
Rapidly eliminated by
exhalation
.
Upper
esophageal sphincter
tone maintained
.
Disadvantages:
Slow
process.
Potential excitement
phase.
Irritant and
unpleasant, may
induce
coughing.
Pollution.
May
cause a
rise in
ICP/IOP
Slide18Inhalation anesthetics
inhalational anesthetics are commonly used
as
an
induction
and
maintenance
agent.
The speed of
induction
of anesthetic
effects
depends on
factors
like:
Solubility
Inspired
gas
partial
pressure
Ventilation
rate
Pulmonary blood
flow
Slide19Induction
depends
on
how
fast
effective
concentrations
of
the anesthetic
drug reach
the
brain.
Preoxygenation
:
Giving
100% O2
prior
to
intubation
>>
increase
lung
functional
residual
capacity
>>Main
mechanism
:
Denitrogination
(washing
Nitrogen
out)(replacing
N volume
with
O2
to
provide a reservoir for diffusion
into
alveolar capillary
blood
after the
onset
of
apnea
Method: 100% O2
via
tight
fitting mask for 5
minutes
in
a
spontaneously breathing
patient
>>>
10 minutes
of O2 reserve
Slide20While
recovery ,
depends on how
fast the
anesthetic drug diffuses
from the
brain.--------- diffusion
hypoxia!!!
While
recovering
from
N2O
anesthesia
Large quantities
of this gas
cross
from
the
blood into
the
alveolus
(down
its
concentration
gradient)
O2
and
CO2
in
the
alveolus
are
diluted
by
this gas for a
short
period of time
Hypoxia
This
is
more common
during
the
first
5-10 minutes
of
recovery
Administration
of
100% O2
is
essential to
overcome this
situation
Slide21Procedure
:
induction > intubation > ventilation > reversal
The mask or hand
is
introduced gradually
to the
face
from
the
side.
While
talking
to the
patient & encouraging him
to
breathe deeply
,
the
anesthetist adjusts
the
mixture of gas flow & observes
the
patient’s
reaction.
initially
N2O 70%
in
O2
is
used.
immediate
8%
sevoflurane
in
70% nitrous
oxide in
oxygen.
Anesthesia deepened by
gradual
introduction of a
volatile
agent
.
(e.g.
halothane1-3%).
A
single
breath technique
for
patients who
are
able
to
cooperate.
Observe
the color of
patient’s skin ,pattern of ventilation, palpate peripheral pulses, monitor ECG& spO2.Insertion of an oropharyngeal airway
, a laryngeal mask airway or tracheal tube may be
considered when anesthesia has been established
Slide22Difficulties and
Complications:
Airway
obstruction
Laryngeal
spasm
Cause:
stimulation during light Anesthesia./insufficient
depth of anesthesia
during induction/irritant
volatile
anesthitics
, infection
Treatment:
stop
stimulation,
gently
deepen anesthesia >> 100%O2
is applied
with
face
mask.
If severe
>>
100%O2
is applied
with
face
mask,
I.V.
*
suxamethonium
*
.
suxamethonium
:
succinylcholine, used
to
cause short-term
paralysis as part
of general anesthesia
,It
is
given either
by injection
into a
vein
or
muscle.
Slide23Bronchospasm
Cause
:
Allergy, smokers,
Irritants, upper respiratory
infection
Treatment
:
increasing
the
depth of anesthesia with
additional induction agent
or volatile agent, or
by
administering
IV
or endotracheal
lidocaine
(local
anesthetic)1-2
mg/kg.
warming
of gases,
bronchodilators.
Malignant
hyperthermia:
Cause
:
volatile
Anesthetics (
halothan
,
suxamethonium
and
local
anesthetics
are
triggering substances).
Life
threatening
:
Due
to
uncontrolled, excessive
increase in
skeletal muscle
oxidative
metabolism
Treatment
:
Dantrolene
IV
antidote
(muscle relaxant that decrease excitation-contraction of
muscles)Raised intracranial pressure (Inhalational to IV)
Slide24Airway maintenance
delivery
of
inhalation
agents
Face
Mask:
Applied
before
and during
and after loss of
consciousness at
anesthetic
induction.
The
mandible
is
held
into
the
mask by
the
anesthetics
(holding rather than pressing)
the
mandible
is
held foreword
,
helping to prevent
posterior
movement
of
the
tongue
and
obstruction of
the
airway.
It has variants of type and
size.
Slide25Airway maintenance
delivery
of
inhalation
agents
2.
Laryngeal Mask
(LMA)
appropriate
depth
of
anesthesia
is
required
1. Patient's
head
is
extended.
2. Mouth
is
opened.
3.
Pre
deflated
LMA
is
inserted into
the
Pharynx.
4.
LMA
is
swept
distally
into
the
laryngopharynx.
5. Inflate
the
cuff.
6.
Confirmation of
the
correct placement.
Slide26Airway maintenance
delivery
of
inhalation
agents
3. T
racheal
intubation.
Slide27Preparation:
The anesthetist must check the availability and function of
the
necessary
equipment
.
should
have a
dedicated and experienced
assistant
.
laryngoscopes of the correct size are
chosen.
patency of tracheal tube is
checked.
Slide28Indications
:
Provision of a
clear
airway
.
Surgical
procedures
in
which
the
anesthesiologist
cannot
easily
control
the airway
(e.g., prone,
sitting,
or
lateral decubitus
procedures).
Head and
neck operation
(nasotracheal
tube).
Protecting
the
respiratory tract from
aspiration
of
gastric
contents (non-fasting
pt
)
Suction
of
the
respiratory
tract
.
Slide29Surgical
procedures
within
the
cranium,
chest
or
abdomen.
Protecting
a
healthy
lung
from
a
diseased
lung
to ensure
its
continued performance
(e.g.
hemoptysis, empyema
&
pulmonary
abscess).
Severe pulmonary and multisystem
injury
associated
with
respiratory
failure
(e.g.,
severe sepsis,
airway
obstruction,
hypoxemia).
Positive-pressure
ventilation
Slide30Slide31Recovery :
The
duration
of
exposure
to the anesthetic
can
have a
marked effect
on
the
time of
recovery.
If
exposure
to the anesthetic
is
short, recovery
may
be
rapid.
Redistribution
from
the
brain
Clearance
of
inhaled anesthetics by the
lungs
into
the
expired
air
is
the
major
route
of
their
elimination
from
the body
Slide32Monitoring of
anesthesia
A)
Routine
monitoring technologies
:
1-
Continuous Electrocardiography
(ECG):
monitor
Heart
rate
and
rhythm
2
-
Continuous pulse
oximetry
(SpO2):
early detection
of a
fall
in
a
patient's
hemoglobin
saturation
with
oxygen
(
hypoxemia)
Pulse oximetry
:
gives
a
continuous
reading
of
the
percentage of oxygen
saturation
of Hb
.
If
below 95%( hypoxemia
)
If
below 90%( severe hypoxemia
)
3-
Blood Pressure
Monitoring
(NIBP
):
Non-invasive
blood pressure regularly
during the surgery.
Slide33Monitoring of
anesthesia
4 -
Agent
concentration
measurement
Common
anesthetic machines
have
monitors
to
measure
the percent
of
inhalational
anesthetic
agent used
(e.g.
sevoflurane, isoflurane, desflurane,
halothane
etc.).
The
monitors also
usually
measure
nitrous
oxide
and
oxygen
percentages
and
could
give
a
MAC
level
.
5-
Carbon
dioxide
measurement
(capnography):
measures
the
amount
of
carbon dioxide
expired by the patient's
lungs
in
percent
or
mmHg
mmHg
is
usually
used
to
allow
the anesthesia
provider to see more subtle changes in
CO2allows the anesthetist to assess the
adequacy of ventilation.6- Temperature measurement:
to discern hypothermia or fever, and to aid early detection of malignant hyperthermia. And
to ensures that the ETT ( endotracheal tube ) is in the respiratory tract and not in the esophagus
.Hypercapnea
increase in minute volume ( by increase in tidal
volume or
respiratory rate
) or
normocapnea
(
PaCO2= 35-45 mmHg
) or
hypocapnea
reduction
in
RR or
tidal
volume
Slide34Monitoring of
anesthesia
B)
Advanced monitoring
technologies
used
in
prolonged bloody operation and/or
in
severely
ill
patients
1)Invasive
blood pressure
(IBP)
monitoring
for
patients with
significant
heart
or
lung
disease
,
the
critically
il
l,
major surgery
such as
cardiac or
transplant
surgery,
or
when
large
blood
losses
are
expected
.
The
invasive
blood
pressure
monitoring
technique
involves placing a
special
type
of
plastic cannula
in
the
patient's
artery
- usually
at
the
wrist
or
in the
groin.
Slide35Monitoring of
anesthesia
2)
Central Venous
Pressure
monitoring
(CVPM)
Monitors
the
preload
(
venous return
)
High
reading
hypervolemia (
give
diuretics )
HF
(
give
diuretics + positive inotropic
agent
)
Low
reading
hypovolemia
***
+/-
0 +10 cm
H2O
(
normal
)
Slide36Thank You