1. General anesthesia

2. Definition of anesthesia
It is a reversable blocking of pain feeling in whole body or in a part of it using pharmacology or other methods

3. Anesthesia- division
Local- regional anesthesia, patient is conscious or sedated General- anesthesia interact with whole body, function of central nervous system is depressed: – Intravenous – Inhalation (volatile) – Combined, balanced

4. TIVA Total Intra Venous Anaesthesia VIMA Volatile Induction and Maintain Anaesthesia

5. Parts of general anesthesia
Hypnosis- pharmacological sleep, reversable lack of consciousness
Analgesia-pain management
Areflexio-lack of reflexes
Relaxatio musculorum- muscle relaxation, pharmacological reversable neuromuscular blockade

6. Parts of general anesthesia must be in balance between:
Hypnosis (anesthesia)
Analgesia
Lack of reflexes (muscle relaxation)

7. Features of General anesthesia
1 Lack of consciousness
2 Pain management
3 Lack of reflexes
4 Neuromuscular blockade

8. Stages of general anesthesia
• Stadium analgesiae (analgesia and sedation stage)
• Stadium excitationis (excitation stage)
• Stadium anaesthesiae chirurgicae (anesthesia for surgery)
• Stadium paralysis respirationis (intoxication, respiratory arrest)

9. I. Analgesia stage • Patient consciouss • Spontaneus respiration • Reflexes present • Possible small surgery procedures like dressing change in burns
II. Excitation stage
• Possible uncontrolled movements, vomitings
• Increase in respiratory rate
III. Anesthesia for surgery
• It begins with lack of lid reflex
• 4 substages
• Airway opening necessary
• Possible surgery except for abdominal opening if no relaxants are used
• Possible endotracheal intubation
IV. intoxication, overdosing
• Respiratory arrest
• If anesthesia not discontinued possible cardiac arrest

10. Main reasons for premedication: Anxiolysis lack of of threat
Sedation – calming down
Amnesia – lack lof memories of perioperative period
Methods of general anesthesia
OPEN OLD
SEMIOPEN USED MOSTLY IN PEDIATRIC ANESTESHIA
SEMICLOSED MOST COMMON
CLOSED MODERN ANESTESHIA

11. Stages of general anesthesia
Methods of general anesthesia CIRCLE SYSTEM *HIGH FLOW FRESH GAS FLOW > 3 l/min. *LOW FLOW FGF ok. 1l/min. *MINIMAL FLOW FGF ok. 0,5 l/min.
Stages of general anesthesia
• Introduction to anesthesia (induction)
• Maintaining of anesthesia (conduction)
• Recovery from anesthesia

12. Anesthesia agents
1. Inhalation anesthetics (volatile anesthetics) - gases : N2O, xenon - Fluids (vaporisers)
2. Intravenous anesthetics - Barbiturans : thiopental - Others : propofol, etomidat
3. Pain killers - Opioids: fentanyl, sufentanil, alfentanil, remifentanil, morphine - Non Steroid Anti Inflamatory Drugs: ketonal, paracetamol
4. Relaxants - Depolarising : succinilcholine - Non depolarising : atracurium, cisatracurium, vecuronium, rocuronium
5. adiuvants -benzodiazepins: midasolam, diazepam

13. Volatile vs intravenous anesthesia

14. Mechanism of action of inhaled anesthetics
Reaction depends on concentration. This depends on alveolar (first compartment), blood and brain (central compartment) concentration , (third compartment- other tissue like muscles, fataccumulation effect):
– Minute ventilation
– Lung blood perfusion
– Solubility in tissues
MAC-minimal alveolar concentration
Concentration in which 50% of anesthetised patients do not
react on skin incision
Corelation with solubility in fat tissue
The lower MAC is the higher strenght of action is

15. Division of inhalation agents
Gases:
• N2O – old, weak, used as adiuvant
• Xenon – lately introduced
2. Vapors (fluids):
• Halothan
• Enfluran
• Isofluran
• Sevofluran
• Desfluran

16. Features of ideal volatile anesthetic
Not disturbing smell
Fast acting, titrable
Low solubility in blood- fast transport to brain
Stable when stored, not reacting with other chemicals
Non- flamable, non- explosive • Low methabolism in body, fast elimination, no accumulative effect
No depressing effect on circulatory and respiratory systems

17. Nitrous oxide • Old • Weak • Used as adiuvant • Will be removed form medical use up to 2010
Halothan
• Used for many years with good effect
• First non-flamable volatile fluid anesthetic
• MAC high
• Depression of circulatory system
• May destroy liver
• Now-a-days used only in pediatric anesthesia

18. Isofluran • Disturbing smell • May interact with heart contractivity • Increases relaxation of muscles
Desfluran
• Very disturbing smell- can not be used for VIMA
• Is not methabolised
• Very fast acting
• May be used for one-day surgery
• Expensive, difficult to store (boiling temp. about 20 C)
• Modern and widelly used

19. Sevofluran • Not disturbing smell- may be used for VIMA • Low solubility in blood- fast acting • Does not disturbs airway • May depress circulatory system • Methabolised to Compound A- may be renal toxic (but not confirmed in humans) • May be used in one-day surgery • Modern, and more and more widely used volatile anesthetic

20. Intravenous anesthesia

21. TCI (target controlled infusion)
TCI is an infusion system which allows the anaesthetist to select the target blood concentration required for a particular effect
It allows to control depth of anaesthesia by adjusting the requested target concentration

22. Instead of setting ml/h or a dose rate (mg/kg/h), the pump can be programmed to target a required blood concentration.
Effect site concentration targeting is now included for certain pharmacokinetic models.
The pump will automatically calculate how much is needed as induction and maintenance to maintain that concentration.

23. THIOPENTAL Old, one of the first used intravenous anesthetics
Depressing effect on circulatory system
May be used in patients with ASA 1

24. Ketamine Only intravenous anesthetic which has good analgesia effect Does not depress circulatory nor respiratory function Used in children, and in emergency and diseaster medicine Gives night mare dreams in adult patients

25. Propofol
Very good anesthetic for induction and maintaince of anesthesia with no accumulation effect
Titrable
May be used in short procedures – titrated do not effect circulatory and respiratory system in important manner
Good for sedation, brain protecting effect
May be used in TCI

26. Opioids fentanyl, alfentanil, sufentanil, remifentanil
May be used for induction and maintain of anesthesia in repeated bolus or continuous infusion technique
Sedative effect
In high doses may be used alone for so called opioid anesthesia- formerly used in cardioanesthesia- very stable circulatory effect

27. Muscle rigidity in high doses Post-Operative Nausea and Vomitings
Compications of use
Respiratory depression
Muscle rigidity in high doses
Post-Operative Nausea and Vomitings
Accumulation effect after prolonged administration (except for remifentanil)

28. No accumulation effect after prolonged
Remifentanil
T1/2 3-5 min
Methabolised by non-specific tissue esterases- methabolism is not altered by renal or liver function
No accumulation effect after prolonged

29. BENZODIAZEPINES Used in anesthesia: Diazepam Midazolam
Used as adiuvants for premedication

30. MUSCLE RELAXANTS

31. 1.nondepolarising- 2.depolarising-
Division of relaxants depending on mechanism of action
1.nondepolarising-
combine with receptor for Ach like antagonists- they are fake mediators
do not cause muscle contractation but block access to receptors for Ach
2.depolarising-
they combine with receptors for Ach and cause contractation of muscle but they stay connected with receptor blocking access to it for Ach.
They act like agonists.

32. Nondepolarising agents
d-tubocurine – oldest deliverate of curarine –
alcuronium
-pancuronium – cheap and still used –
pipercuronium –
vercuronium –
atracurium –
cisatracurium –
mivacurium
-rocuronium

33. Division of nondepolarising relaxants due to Chemical structure:
AMINOSTEROIDS
Pankuronium( Pavulon )
Pipekuronium( Arduan )
Rapakuronium ( Raplon )
Rokuronium ( Esmeron )
Wekuronium ( Norcuron )

34. Benzylizochinolons
Miwakurium( Mivacron )
Cisatrakurium( Nimbex )
Atrakurium(Trakurium)

35. Division of nondepolarising relaxants due to time of action:
Short acting < 3 min: still searching
Midle time <60 min: mivacurium, atracurium, cisatracurium, rocuronium, vecuronium
Long acting > 60 min: pancuronium, pipecuronium

36. Atracurium
Elimination non-enzymatic, independent of renal and liver function, Hoffman elimination- hydrolisis
Releases histamine
Acts about 30 min
Cisatracurium
One of stereoisomers of atracurium,
Do not release histamine
Acts about 60 min

37. Rocuronium
Fast acting- time to 100% supresion 60 sec.
Do not release histamine
Acts about 60 min
Is methabolised in liver- disfunction of liver may alter elimination
Mivacurium
Releases histamine
Acts about min – used for short procedures
Methabolised by plasma esterases

38. Reverse of neuromuscular blockade
Neostigmine, piridostigmine- blockers of acetylocholinesterase
Must be given toghether with atropine to avoid bradycardia caused by activation of perisympatic system
Depolarising agents
Only one: chlorsuccinilocholine –
It is methabolised by pseudocholinesterase - Causes many complications, has many contraindications –
Indications: Rapid sequence induction: full stomach, suspected difficult intubation because it acts very fast < 30 seconds and short < 3 min

39. Complications of general anesthesia
Respiratory: residual relaxants/opioids action
Circulatory
Neurological: residual anesthetics/opioids action
Post-Operative Nausea and Vomitings

40. Mortality connected with anesthesia 0,05 0,05 - 4/10000 GA
% of of surgical surgical patients patients
80 % is is caused caused by by human human mistakes
Major causes of deaths
Airway obstruction
Difficult and and unefficient intubation
Insufficient ventillation

41. Haemodynamic instability Aspiration Aspiration Toxity of drugs drugs
Other causes of mortality and morbidity
Anoxia
Haemodynamic instability
Aspiration Aspiration
Toxity of drugs drugs
mostly inhalation agents
Anaphylaxia and and drug interations