/
Conduction  of   anesthesia Conduction  of   anesthesia

Conduction of anesthesia - PowerPoint Presentation

hadley
hadley . @hadley
Follow
342 views
Uploaded On 2022-02-14

Conduction of anesthesia - PPT Presentation

Done by Osama Alfaqeh Types of anesthesia Local Anesthesia Regional Anesthesia Spinal anesthesia injected into the spinal fluid Epidural anesthesia outside ID: 908803

induction anesthesia airway anesthetic anesthesia induction anesthetic airway loss anesthetics inhalation stage monitoring pressure respiratory agent centers mask blood

Share:

Link:

Embed:

Download Presentation from below link

Download Presentation The PPT/PDF document "Conduction of anesthesia" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.


Presentation Transcript

Slide1

Conduction of anesthesia

Done by

Osama Alfaqeh

Slide2

Types

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

)

Slide3

Slide4

Slide5

What

is

the “perfect”

anesthetic?

Slide6

MODERN 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

)

Slide7

Depth 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.

Slide8

stages

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.

Slide9

stages

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

Slide10

stages

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

Slide11

stages

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

Slide12

Phases 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.

Slide13

Inhalation 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

.

Slide14

Phases 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

Slide15

Phases 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

Slide16

IV

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.

Slide17

Inhalation 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

Slide18

Inhalation 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

Slide19

Induction

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

Slide20

While

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

Slide21

Procedure

:

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

Slide22

Difficulties 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.

Slide23

Bronchospasm

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)

Slide24

Airway 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.

Slide25

Airway 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.

Slide26

Airway maintenance

delivery

of

inhalation

agents

3. T

racheal

intubation.

Slide27

Preparation:

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.

Slide28

Indications

:

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

.

Slide29

Surgical

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

Slide30

Slide31

Recovery :

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

Slide32

Monitoring 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.

Slide33

Monitoring 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

Slide34

Monitoring 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.

Slide35

Monitoring 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

)

Slide36

Thank You