4. Principles of anesthesia.pptx

Principle of anesthesia

1. Principles of Anesthesia Firaol R.(MSc) 1

2. Learning Objectives Firaol R.(MSc) 2 Differentiate among local, Regional and general anesthesia. Mention the routes of administering local anesthesia. Identify two methods of administering general anesthesia. Manage the adverse effects of local anesthesia. Identify the stages of general anesthesia.

3. Principles of anesthesia Firaol R.(MSc) 3 A n esthe s ia Is the abs e nce o f s ens a t i on whi c h may b e produced in Specific body area or systemically . Anesthesiology –Branch of medicine concerned with the administration of anesthetic agent to relieve pain and support physiologic function during a surgical procedure .

4. Principles of anesthesia… Common terms in anaesthesia Analgesia - lessening sensitivity to pain (Pain relief without loss of feeling or movement) Anastasia – loss of feeling or sensation of pain Anaesthetic - drug that induce loss of sensitivity 4

5. Common terms… Anaesthetist - person who trained to administer anaesthesia Anaesthesiologist - medical doctor who trained to administer anaesthesia Anoxia –absence of oxygen 5

6. Common terms… Hypnosis - a state of altered consciousness Hypnotic – a drug that induces sleep Assisted respiration - the maintenance of adequate alveolar ventilation by supplementing the patients respiration by manual or mechanical means. 6

7. Common terms… Apnea - cessation of breathing Induction - period from administration up to loss of pain 7

8. Principles of anesthesia Firaol R.(MSc) 8 Types of anesthesia Local anesthesia Regional anesthesia General anesthesia

9. A) Local anesthesia Firaol R.(MSc) 9 Used to numb a small site for minor procedures They act on afferent nerve fibers –more on nociceptors Prevents generation and conduction of action potential It acts on a single nerve , a group of nerves or on superficial nerve endings and blocks the conduction of pain . During all types of local anesthesia, the patient remains conscious

10. A) Local anesthesia Firaol R.(MSc) 10 Examples of local anesthesia Lidocaine –Has rapid induction, good penetration Bupivacaine –has slow onset, long duration , commonly used in long surgeries, m e dium tis s u e ha s high card i o penetratio n, to x ic i t y .

11. A) Local anesthesia Firaol R.(MSc) 11 Advantages : It needs minimal and simple equipment Loss of consciousness doesn’t occur It doesn’t need fasting/NPO Surgeon can administer with out anesthesiologist

12. A) Local anesthesia… Firaol R.(MSc) 12 Contra indication to local anesthesia Allergic sensitivity Local infection Septicemia H ypertension

13. A) Local anesthesia… Firaol R.(MSc) 13 Local anesthesia can be given in different ways Local infiltration Nerve block Topical

14. 1) Local infiltration The agent is injected intracutaneously and subcutaneously into tissues at and around the incisional site to block peripheral sensory nerve stimuli at their origin . The surgery should not be extensive • It is used to suture superficial lacerations or for excision of minor lesions 14

15. Local infiltration… Adrenaline is added to prolong anesthesia & minimize local bleeding Addition of Adrenaline (Epinephrine) to the anesthetic agent causes vasoconstriction to slow circulatory uptake and absorption, thus prolonging anesthesia Use a calibrated syringe to avoid over dosage 15

16. Local infiltration… The patient receiving Adrenaline should be well oxygenated • Agents with Adrenaline are contraindicated for operative procedures involving fingers and penis • High levels of local anesthetic are toxic 16

17. Local infiltration… Administration of it takes place as part of the sterile procedure - use sterile needle and syringe. When highly vascularized areas are to be injected, epinephrine is sometimes added to the anesthetic (to minimize local bleeding, prolong the effect of the agent). 17

18. Local infiltration… 18

19. A) Local anesthesia… Firaol R.(MSc) 19 Nerve block Anesthesia of a large single nerve or nerves Injection is done not necessarily at the immediate surgical site . The nerve supplying body part is anesthetized Commonly used in surgery that is performed on fingers and toes.

20. Nerve block… Firaol R.(MSc) 20

21. A) Local anesthesia… Firaol R.(MSc) 21 3) Topical Used to numb sup e r ficial ner v e endi n gs particularl y those o f the mucous membranes Th e agent may b e sw a bbed, sprayed o r ap p lied i n drops a s for eye surgery Us e f u l i n prepa r ing t h e patient for en d oscopic procedures, such as bronchoscopy and esophagoscopy.

22. B) Regional Anesthesia Firaol R.(MSc) 22 Is use of local anesthetics to block sensations of pain from large area of the body like arm, leg or abdomen It is Method of blocking of nerve impulses before they reach the central nervous system in order to induce analgesia. B e fore pe rfor m i n g c o nd u ct i on b l o ck , full fac i liti e s for resuscitation should be available

23. Cheap High Patient Satisfaction Maintain Patent Airway Decreased blood Loss Selective Muscle Relaxation Decreased Incidence of DVT & PE B) Advantage of r egional Anesthesia Firaol R.(MSc) 23

24. Hypotension Risk of toxicity Many patients prefer to be asleep Skills are required Patient Can talk Patient Anxiety Not Reliable for Surgery > 2 hours B) Dis adv. of r egional Anesthesia Firaol R.(MSc) 24

25. Re g i o n a l An e sth e sia… Firaol R.(MSc) 25 between spinal fluid and anesthetic). The patient s h ou l d b e c l o s ely wat c hed C 1 N 6 S,CVS,R S … Epidural The agent is Introduced into the epidural space of the spine The agent baths the nerve roots of the spinal cord and the area supplied by these nerves is anesthetized The anesthetic is injected outside the spinal canal (no direct contact b e c au s e anesthetics a f fe c t

26. Epidural …. Firaol R.(MSc) 26

27. 2) Spinal anesthesia Firaol R.(MSc) 27 Anesthetic agent is injected into the subarachnoid space at the 4 th or 5 th lumbar interspace. Anesthetic agent does come into contact with the spinal fluid Used for s urgery o f t h e lo w er pelv i s, such a s cesarean sect i on or hernia repair; lower extremities. I t ha s risk o f i n fect i o n i n the sp i n al c a nal i f the pu n cture s ite is contaminated.

28. Firaol R.(MSc) 28

29. 2)Spinal anesthesia… S pinal absorption depends on : Position during and immediately after injection CSF pressure Volume and dose 29

30. 2)Spinal anesthesia… Common position for spinal anaesthesia Lateral position- the most common Prone position Sitting position 30

31. Anesthetic agent Uses Duration of action Dosage Bupivacaine hydrochloride Local Regional block epidural 2-3hr 400mg Procaine hydrochloride Infiltration Spinal nerves ¼- ½ hr. 100mg or 14mg/kg) Cocaine hydrochloride Topical ½ hr. 200mg(4mg/kg) Lidocaine hydro c hlo r ide( x y l o c aine) Topical Infiltration, peripheral nerve, nerve block, spinal, epidural ½- 2hr 200mg 500mg or 7mg/kg Tetra Caine hydrochloride T opi c al Spinal 2-4 hr 20mg Common Local and regional Anesthetic Agents Firaol R.(MSc) 31

32. Adverse reactions to local anesthesia Firaol R.(MSc) 32 Stimulation : patient may become very talkative or anxious, signs of tachycardia , thready pulse, convulsion. Depres s io n : pati e nt may ap p e ar sleepy and unresponsi v e , bradycardia, hypotension. Oth e r si g n s : pati e nt may dev e lop cyan o s i s, sw e ating , feel col d , restless (signs of shock) ,d izzness , headaches , blurred vision etc..

33. Treatment of the Reaction Firaol R.(MSc) 33 Discontinue the anesthetic immediately Oxygen administration may be needed Cardiopulmonary resuscitation is initiated, if necessary .

34. C) General Anesthesia Firaol R.(MSc) 34 Causes unconsciousness , provides analgesia and muscle relaxation A comb i na t i o n o f d i ff e rent a n esth e tic a g ents i s fre q u e ntly used to achieve the desired level of muscle relaxation and analgesia. Intravenous and inhaled gases may be used It is medically induced coma

35. Ge n er a l An e sth e sia… Firaol R.(MSc) 35 There are four stages of general anesthesia. Induction Excitement Relaxation Danger

36. 1) Induction Firaol R.(MSc) 36 Is a period when the patient goe s f r om consciou s nes s to unconsciousness. Lasts until the patient is unconscious During this phase, the patient retains an exaggerated sense of hearing so it is mandatory to remain as quiet as possible during induction.

37. 2) Excitement Firaol R.(MSc) 37 D u r ing this ph a se, t h e patient i s delir i ous an d sens i tive to e x t e rn a l stimuli Involuntary muscle activity and struggle may be seen The critical phase for different adverse events Thrashing, vomiting, laryngospasms and dysrhythmias Patient is physiologically unstable

38. 3) Relaxation(surgical phase) Firaol R.(MSc) 38 In this stage there is gradual loss of muscle tone and reflex. This phase is the level at which surgery may be performed safely. Th e patie n t i s relaxed, unc o n s cious o f p ain an d i s phys i o logical ly stable Breathing is steady and automatic This phase ends at its deepest level with respiratory paralysis .

39. Firaol R.(MSc) 39 4) Danger This stage begins when the amount of d e press i on o f the c e n t r al n e r vo u s sys t em immediate danger of cardiopulmonary arrest . agent caus e s seve r e that t he p a t i e n t i s in

40. Methods of Administering General Anesthesia Firaol R.(MSc) 40 1) Inhalation In this case the an e sthetic agen t i s admi n istered b y an e s t hesia machine Th e most contro l la b le met hod i n the u p take an d elim i nation of anesthetic agent Are mainly accomplished by pulmonary ventilation The blood and lungs functioning as the transporting system

41. Inhalation… Firaol R.(MSc) 41 The techniques of inhalation anesthetic used are: A) Mask inhalation : in closed system of anesthetic machine. Excess carbon dioxide is absorbed by soda lime . B) Endotracheal administration : inhaled in the trachea through nasal or oral tube insertion Intubation : insertion of tube directly in to the trachea

42. Inhalation anesthetic agents Firaol R.(MSc) 42 Few side effect except headache, Vertigo and drowsiness Excellent analgesia for minor operation Disadvantage P oor relaxation, excitement, laryngospasm and hypoxia Nitrous oxide(N 2 O) C o mfor t a b l e , rapid irritating i n d u ct i on and recover y , no n t o xic an d non

43. Inhalation anesthetic agents … Firaol R.(MSc) 43 Cyclo propane Very potent gas very seldom used, highly explosive Advantage Pleasant, rapid induction, moderate relaxation, support circulation Disadvantage: Flammable, explosive

44. Inhalation anesthetic agents … Firaol R.(MSc) 44 Halothane (fluothane) Volatile liquids ,very widely used, Has a pleasant odor Advantages: Non flammable, potent ,chemically stable, rapid induction Non - ir r itating for r e sp i rato r y tract, d o e s n’ t stimula te respiratory secretion Useful for patients with bronchial asthma

45. Inhalation anesthetic agents … Firaol R.(MSc) 45 Disadvantage Potentially toxic to liver Respiratory, CVS depressant Hypotension, bradycardia,cardiac arrest

46. 2) Intravenous (IV) and intramuscular (IM) administrations Firaol R.(MSc) 46 Injections are also used in general anesthesia. Liquid agents may be administered directly into the blood stream. A continuous intravenous drip is maintained throughout surgery.

47. Intravenous agents Firaol R.(MSc) 47 Thiopental sodium (pentothel sodium) Short acting in small doses and used for induction Advantage Pleasant rapid induction Non flammable and non irritating Nausea and vomiting are rare Large dose caus e s rapid ; p r olo n ged r e s p iratory depression Coughing, laryngospasm and circulatory

48. Intravenous agents Firaol R.(MSc) 48 Ketamine hydrochloride Can be administered IV or IM Produces rapid induction (30 seconds IV and 2-4 minutes IM) Advantage: Used for short procedure-in children (age 2-10 yrs.) for plastic and eye procedure

49. Intravenous agents Firaol R.(MSc) 49 Disadvantage: Emergence reactions with psychologic manifestations in recovery periods like delirium ,hallucination , increase B/P

50. Choice of Anesthesia Firaol R.(MSc) 50 Choice of anesthesia is made by anesthesiologist or surgeon Anesthetic drugs depress activities of all cells. So the primary consideration with any anesthetics is that it should be associated with low morbidity and mortality

51. Choice of Anesthesia… Firaol R.(MSc) 51 The one who select the anesthetic agent should include some or all of the following: Provide maximum safety and comfort for the patient Provide optimum operating condition Have a low index of toxicity Provide potent, predictable analgesia extending to post operative period

52. Choice of Anesthesia… Firaol R.(MSc) 52 Produce adequate muscle relaxation Provide amnesia(forget fullness) Have rapid onset and easy reversibility Provide minimum side effect

53. The factors to consider during anesthesia Firaol R.(MSc) 53 Age of the patient Physical and mental status of the patient Presence of complicating systemic disease Previous anesthesia experience Position required for operation

54. The factors to consider … Firaol R.(MSc) 54 Type and expected length procedure Local and systemic toxicity of the agent Expertise of the anesthesiologist Presence of infection at the site of operation Preference of the patient

55. Pre-medication Firaol R.(MSc) 55 It is the type of medication given to the client prior to operation in order to alleviate anxiety. It is usually given 45-60 minutes prior to induction. Purposes of premedicatio n To alley pre-operative anxiety T 4 o 3 have dull awareness of the OR environment

56. Pre-medication… Firaol R.(MSc) 56 Purposes of premedication … It decreases secretion in the respiratory tract It counter act undesirable side effect of anesthesia Prolong t h e e f fe c t o f the a n esth e tic an d i n crease a resp i ratory depressant effect

57. Pre-medication… Firaol R.(MSc) 57 The 4 common classes of pre medications are; Barbiturates (Nembutal, Secobarbital) Produces a hypnotic effect as sedatives Opiates (Metapon, Demerol, Morphine) Act as analgesia Produces narcosis (unconsciousness)

58. Pre-medication… Firaol R.(MSc) 58 Belladonna Derivatives (Atropine, scopolamine) Inhibit mucus secretion Tranquilizers (valium, vistaril, chlorpromazine) These relax and allay apprehension and allow for smooth induction. Reduce anxiety , fear and tension

59. Special considerations in pre-medication Firaol R.(MSc) 59 Hypnotics : is valuable as a premedicant - in children Heavy smokers, a l coh o l i cs hy p er thyroi d , to x ic, emotional, h i gh fever patients require more medication .

60. The nurses role in anesthetized patient Firaol R.(MSc) 60 The patient position P a tien t ’ s ability to tolerate stress d e t o x if y , a n esth e tic a g ents(l i v er functi o n) and Patient’s respiratory and circulatory care T eam memb e rs must b e constan tly aw a re o f potential t r au m a t o the patient