anesthesiology
Download
Skip this Video
Download Presentation
Anesthesiology

Loading in 2 Seconds...

play fullscreen
1 / 37

Anesthesiology - PowerPoint PPT Presentation


  • 438 Views
  • Uploaded on

Anesthesiology Anesthesia – is a reversible condition of comfort, quiescence and physiological stability in a patient before, during and after performance of a procedure. General anesthesia – for surgical procedure to render the patient unaware / unresponsive to the painful stimuli.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Anesthesiology' - paul


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
anesthesiology
Anesthesiology
  • Anesthesia – is a reversible condition of comfort, quiescence and physiological stability in a patient before, during and after performance of a procedure.
  • General anesthesia – for surgical procedure to render the patient unaware / unresponsive to the painful stimuli.
anesthesiology2
Anesthesiology

Original in the Royal College of Surgeons of England, London.

anesthesiology3
Anesthesiology
  • Surgical stress – evokes HPA axis and sympathetic system.
  • Tissue damage during surgery induces coagulation factors and activates platelets leading to hypercoagulability of blood.
  • Anesthesia decreases the components of surgical stress response.
anesthesiology4
Anesthesiology

Anesthetics are associated with

  • Decrease in systemic blood pressure – myocardial depression and direct vasodilatation.
  • Blunting of baroreceptor control and decreased central sympathetic tone.
anesthesiology5
Anesthesiology

Hallmark of anesthesia:

  • Amnesia / unconsciousness
  • Analgesia
  • Muscle relaxation

General anesthetics have therapeutic indices of about 2 - 4.

anesthesiology6
Anesthesiology

Preanesthetic medication:

It is the use of drugs prior to anesthesia to make it more safe and pleasant.

  • To relieve anxiety – benzodiazepines.
  • To prevent allergic reactions – antihistaminics.
  • To prevent nausea and vomiting – antiemetics.
  • Toprovide analgesia – opioids.
  • To prevent bradycardia and secretion – atropine.
anesthesiology7
Anesthesiology

Stages of anesthesia:

  • Stage I : Analgesia
  • Stage II : Excitement, combative

behavior – dangerous state

  • Stage III : Surgical anesthesia
  • Stage IV : Medullary paralysis –

respiratory and vasomotor

control ceases.

anesthesiology8
Anesthesiology

Molecular mechanism of the GA :

  • GABA –A : Potentiation by Halothane,

Propofol, Etomidate

  • NMDA receptors : inhibited by Ketamine
anesthesiology9
Anesthesiology

The main target of inhalation anesthetics is the brain.

anesthesiology10
Anesthesiology

There are two types of anesthetics :

  • Inhalational --- for maintenance
  • Intravenous --- for induction and short procedures

Inhalation anesthetics:

  • Advantage of controlling the depth of anesthesia.
  • Metabolism is very minimal.
  • Excreted by exhalation.
anesthesiology11
Anesthesiology

Inhalational anesthetics :

Non-halogenated gas:

  • Nitrous oxide

Halogenated hydrocarbons:

  • Halothane
  • Enflurane
  • Isoflurane
  • Desflurane
  • Sevoflurane
  • Methoxyflurane – nephrotoxicity.
anesthesiology12
Anesthesiology

The important characteristics of Inhalational anesthetics which govern the anesthesia are :

  • Solubility in the blood (blood : gas partition co-efficient)
  • Solubility in the fat (oil : gas partition co-efficient)
anesthesiology13
Anesthesiology

Blood : gas partition co-efficient:

  • It is a measure of solubility in the blood.
  • It determines the rate of induction and recovery of Inhalational anesthetics.
  • Lower the blood : gas co-efficient – faster the induction and recovery – Nitrous oxide.
  • Higher the blood : gas co-efficient – slower induction and recovery – Halothane.
anesthesiology15
Anesthesiology

Blood gas partition co-efficient affecting rate of induction and recovery

slide16
Agents with low solubility in blood quickly saturate the blood. The additional anesthetic molecules are then readily transferred to the brain.

BLOOD GAS PARTITION COEFFICIENT

anesthesiology18
Anesthesiology

Oil: gas partition co-efficient:

  • It is a measure of lipid solubility.
  • Lipid solubility - correlates strongly with the potency of the anesthetic.
  • Higher the lipid solubility – potent anesthetic. e.g., halothane
anesthesiology19
Anesthesiology
  • MAC value is a measure of inhalational anesthetic potency.
  • It is defined as the minimum alveolar anesthetic concentration ( % of the inspired air) at which 50% of patients do not respond to a surgical stimulus.
  • MAC values are additive and lower in the presence of opioids.
slide20
OIL GAS PARTITION CO-EFFICIENT

Higher the Oil: Gas Partition Co-efficient lower the MAC . E.g., Halothane

0.8

1.4

220

inhalational anesthetics
Inhalational anesthetics

Nitrous oxide:

  • Safest inhalational anesthetic.
  • Weak anesthetic but a good analgesic.
  • No toxic effect on the heart, liver and kidney.
  • Caution about diffusional hypoxia megaloblastic anemia.
inhalational anesthetics23
Inhalational anesthetics

Halothane:

  • It is a potent anesthetic.
  • Induction is pleasant.
  • It sensitizes the heart to catecholamines.
  • It dilates bronchus – preferred in asthmatics.
  • It inhibits uterine contractions.
  • Halothane hepatitis and malignant hyperthermia can occur.
inhalational anesthetics24
Inhalational anesthetics

Enflurane:

  • Sweet and ethereal odor.
  • Generally do not sensitizes the heart to catecholamines.
  • Seizures occurs at deeper levels –contraindicated in epileptics.
  • Caution in renal failure due to fluoride.
inhalational anesthetics25
Inhalational anesthetics

Isoflurane:

  • It is commonly used with oxygen or nitrous oxide.
  • It do not sensitize the heart to catecholamines.
  • Its pungency can irritate the respiratory system.
inhalational anesthetics26
Inhalational anesthetics

Desflurane:

  • It is delivered through special vaporizer.
  • It is a popular anesthetic for day care surgery.
  • Induction and recovery is fast, cognitive and motor impairment are short lived
  • It irritates the air passages producing cough and laryngospasm.
inhalational anesthetics27
Inhalational anesthetics

Sevoflurane:

  • Induction and recovery is fast.
  • It is pleasant and acceptable due to lack of pungency.
  • It do not cause air way irritancy.
  • Concerns about nephrotoxicity.
anesthesiology29
Anesthesiology

Parenteral anesthetics (IV):

  • These are used for induction of anesthesia.
  • Rapid onset of action.
  • Recovery is mainly by redistribution.
  • Also reduce the amount of inhalation anesthetic for maintenance.
  • E.g., includes thiopental, midazolam propofol, etomidate, ketamine.
anesthesiology30
Anesthesiology

Thiopental (Pentothal):

  • It is an ultra short acting barbiturates.
  • Consciousness regained within 10-20 mins by redistribution to skeletal muscle.
  • It do not increase ICT.
  • It is eliminated slowly from the body by metabolism and produce hang over.
  • It can be used for rapid control of seizures.
intravenous anesthetics
Intravenous anesthetics

Propofol (Diprivan):

  • Most commonly used IV anesthetic.
  • Unconsciousness in ~ 45 seconds and lasts ~15 minutes.
  • Anti-emetic in action.
  • Suited for day care surgery - residual impairment is less marked.
intravenous anesthetics32
Intravenous anesthetics

Etomidate:

  • It is a short acting anesthetic.
  • It suppress the production of steroids from the adrenal gland and no repeated injections.
  • It is a pro-convulsant and emetic.
  • CVS stability is the main advantage over anesthetics.
intravenous anesthetics33
Intravenous anesthetics

Ketamine : Dissociative anesthesia

  • Produce - profound analgesia, cataleptic state, immobility, amnesia with light sleep.
  • Acts by blocking NMDA receptors
  • Heart rate and BP are elevated due to sympathetic stimulation.
  • Respiration is not depressed and reflexes are not abolished.
intravenous anesthetics34
Intravenous anesthetics

Ketamine:

  • Emergence delirium, hallucinations and involuntary movements occurs in 50% cases during recovery.
  • It is useful for burn dressing and trauma surgery.
  • Dangerous for hypertensive and IHD.
intravenous anesthetics35
Intravenous anesthetics

Neuroleptanalgesia :

  • It is characterized by general quiescence, psychic indifference and intense analgesia without total loss of consciousness.
  • Combination of Fentanyl and Droperidol as Innovar
intravenous anesthetics36
Intravenous anesthetics

Neuroleptanalgesia :

  • It is associated with decreased motor functions, suppressed autonomic reflexes, cardiovascular stability with mild amnesia.
  • It causes drowsiness but respond to commands.
  • Used for endoscopies, angiography and minor operations.
ad