Principles of Anaesthesia 2425 Handouts PDF

Principles of Anaesthesia Dr Jacynta Jayaram Topic learning outcomes 1. Define anaesthesia, describing its purpose, components, and implications in surgical care. 2. Distinguish between general, regional, local, and combined anaesthesia, identifying clinical indications and applicat...

Principles of Anaesthesia Dr Jacynta Jayaram Topic learning outcomes 1. Define anaesthesia, describing its purpose, components, and implications in surgical care. 2. Distinguish between general, regional, local, and combined anaesthesia, identifying clinical indications and applications for each type. 3. Describe the four stages of anaesthesia according to Guedel’s classification, emphasizing the symptoms, risks, and management strategies at each stage. 4. Describe the phases of general anaesthesia: induction, maintenance, emergence, and recovery, highlighting patient management and monitoring during each phase. 5. Explain the induction process of general anaesthesia, from preoxygenation to securing the airway, including induction agents and basic awareness of paediatric considerations that students may encounter during clinical attachments. 6. Explain the steps of rapid sequence induction (RSI), detailing the procedures, agents used, and strategies to minimize aspiration risk. Prior Knowledge 1. Anatomy of the respiratory system 2. Mechanics of breathing 3. Spirometer & lung capacities 4. Composition of atmospheric air History of Anesthesia 1500’s Coca leaves Dr Jacynta Jayaram  History of Anesthesia William Morton (dentist) removed a tumour from the Crawford W. Long used ether jaw of a patient. He rendered for surgical removal of a the patient unconscious tumor from a man’s neck, prior to surgery using a Queen Victoria gave birth to Ether discovered by Spanish but did not publish his sponge soaked in ether. her 8th child, Prince Leopold chemist Raymundus Lillius findings until 1848 Ether dome after inhaling chloroform 1725 1800’s 1842 1845 1846 1840’s 1853 Social use of Ether (Ether Horace Wells used nitrous James Simpson first used frolics) oxide to extract teeth, chloroform however his patient cried out in pain during a demonstration Dr Jacynta Jayaram What is Anesthesia? Anaisthetos (Greek) Without Sensation Dr Jacynta Jayaram The A’s of Anesthesia Controlled, Reversible state of : vAnalgesia – Lack of pain vAmnesia – Lack of recall vAkinesia – Lack of movement vAreflexia – Loss of muscle reflexes vAnxiolysis- Control of anxiety vHypnosis – Loss of consciousness Dr Jacynta Jayaram  Types of Anesthesia no need General Regional esthetist for this Local Anesthesia and Anesthesia Anesthesia neuvaxial Intermittent Spontaneous Monitored positive pressure Craniocaudal Other regions Pure LA respiration Anaesthesia Care ventilation ↳ for unstable pt GASR GA APPV - monitored by anaesthetist machine ↳ for pt reg a lot of sedation ventilating Eg : brachial Eg : Spinal, iron lung plexus, femoral, - paralysis epidural, CSE,CSA we breathe by negative polio-resp M/s TAP ↳ ventilator pressure -ve pressure ISE : Combined spinal epidural anaesthesia anaesthesia CSA : Cont spinal (post-grad) Dr Jacynta Jayaram Combined Eg General Eg General Anaesthesia + Anaesthesia + Regional Local Anaesthesia Anaesthesia GA TAHBSO epidural + eg appendice tomy - eg :  Stage I : Analgesia Stage II : Excitement Guedel’s Stages of Anaesthesia Stage III : Surgical Anesthesia Stage IV : Overdose  Stage I (Analgesia) Stage 1 - Analgesia or Disorientation: This stage can be initiated in a preoperative anesthesiology holding area, where the patient is given medication and may begin to feel its effects but has not yet become unconscious. This stage is usually described as the "induction stage." Patients are sedated but conversational. Breathing is slow and regular. At this stage, the patient progresses from analgesia free of amnesia to analgesia with concurrent amnesia. This stage comes to an end with the loss of consciousness.  Stage II (Excitement) Stage 2 - Excitement or Delirium: This stage is marked by disinhibition, delirium, uncontrolled movements, loss of eyelash reflex, hypertension, and tachycardia. Airway reflexes remain intact during this phase and are often hypersensitive to stimulation. Airway manipulation during this stage of anesthesia should be avoided, including both the placement and removal of endotracheal tubes and deep suctioning maneuvers. At this stage, there is a higher risk of laryngospasm (involuntary tonic closure of vocal cords), which any airway manipulation may aggravate. Consequently, the combination of spastic movements, vomiting, and rapid, irregular respirations can compromise the patient's airway. Fast-acting agents help reduce the time spent in stage 2 as much as possible and facilitate entry to stage 3.  Stage III (Surgical Anaesthesia) Stage 3 – Surgical Anaesthesia: The targeted anaesthetic level for general anaesthesia procedures. Ceased eye movements and respiratory depression are the hallmarks of this stage. Airway manipulation is safe at this level. There are 4 "planes" described for this stage. Plane 1 : there is still regular spontaneous breathing, constricted pupils, and central gaze. However, eyelid, conjunctival, and swallow reflexes usually disappear in this plane. Plane 2 : there are intermittent cessations of respiration along with the loss of corneal and laryngeal reflexes. Halted ocular movements So and increased lacrimation may also occur. that Plane 3 : marked by complete relaxation of ideal no response the intercostal and abdominal muscles and plane to say loss of the pupillary light reflex. This plane is incision called "true surgical anesthesia" because it is ideal for most surgeries. Plane 4 : marked by irregular respiration, paradoxical rib cage movement, and full diaphragm paralysis resulting in apnea Stage IV (Overdose) Stage 4 - Overdose: This stage occurs when too much anesthetic agent is given relative to the amount of surgical stimulation, which results in the worsening of an already severe brain or medullary depression. This stage begins with respiratory cessation and ends with potential death. Skeletal muscles are lax, and pupils are fixed and dilated at this stage. Blood pressure is typically significantly lower than normal, with weak and thready pulses due to the suppression of the cardiac pump and vasodilation in the peripheral bloodstream. Without cardiovascular and respiratory support, this stage is lethal. Hence, the anaesthetist's goal is to transition the patient as soon as possible to stage 3 of anesthesia and keep them there for the duration of the operation Phases of General Anesthesia Surgical Anesthesia Anesthesia begins administration stops Induction Maintenance Emergence Recovery Post anaesthesia care Unit (PACUS/ Begin End of Recovery day Administration Surgery / to before for recover Stimulus - area pt of Anesthesia to ward until they are stable going Dr Jacynta Jayaram Usual ‘Sequence’ of Anesthesia to according urgency ↑ Emergency Surgery Elective Surgery Patient presents to hospital Need for elective Surgery predetermined Admission, clerking, diagnosis (Clinic/prev admission) Need for surgery determined Pre op assessment done either clinic / Posted to anesthetist oncall ward : deemed fit for Surgery, consent Paedspusuale out Determination of fitness Scheduled in elective list want them to fast so long for surgery. Eg further Ix, Pre op stabilisation, adequate Fasting, consent Dr Jacynta Jayaram Patient called to OT Dr Jacynta Jayaram Dr Jacynta Jayaram Usual ‘Sequence’ of Anesthesia In OT – Received by OT nurse. Checklist verified Anesthetist in charge reviews patient – correct patient, surgery review of notes & investigations – deemed fit for surgery Patient pushed into theater that has been prepared earlier SSSL checklist, consent, procedure Application of monitors Establishment of functioning, secure IV access Commencement of anesthesia Dr Jacynta Jayaram Airlock  L to minimize medical error SAFE SURGERY SAFE SURGERYSAVES LIVESLIVES SAVES Dr Jacynta Jayaram Dr Jacynta Jayaram Usual ‘Sequence’ of Anesthesia In OT – Received by OT nurse. Checklist verified Anesthetist in charge reviews patient – correct patient, surgery review of notes & investigations – deemed fit for surgery Patient pushed into theater that has been prepared earlier SSSL checklist, consent, procedure Application of monitors Establishment of functioning, secure IV access Commencement of anesthesia Dr Jacynta Jayaram OT Preparation üAnesthetic machine check üAlternative methods of ventilationeg : Ambo bug üEmergency drugs üAnesthesia drugs specific for case üAny other specific equipment for case Dr Jacynta Jayaram Usual ‘Sequence’ of Anesthesia In OT – Received by OT nurse. Checklist verified Anesthetist in charge reviews patient – correct patient, surgery review of notes & investigations – deemed fit for surgery Patient pushed into theater that has been prepared earlier SSSL checklist, consent, procedure Application of monitors Establishment of functioning, secure IV access Commencement of anesthesia Dr Jacynta Jayaram Anaesthesia SSSL Check list Usual ‘Sequence’ of Anesthesia In OT – Received by OT nurse. Checklist verified Anesthetist in charge reviews patient – correct patient, surgery review of notes & investigations – deemed fit for surgery Patient pushed into theater that has been prepared earlier SSSL checklist, consent, procedure Application of monitors Establishment of functioning, secure IV access Commencement of anesthesia Dr Jacynta Jayaram General Anesthesia : Steps Preoxygenation Induction agent ± volatile agent Spontaneous respiration Test ventilation Hold mask / LMA Muscle relaxation Intubation Confirm that airway is secured Stabilise vital signs Positioning & commencement of surgery Dr Jacynta Jayaram Preoxygenation The administration of 100% oxygen to a patient prior to intubation What? How? Why?  PREOXYGENATION fiO : fruction of inspired O go from 21 % - 100 % Optimising Preoxygenation 10 21). (1. 0) What? 1. 100% Oxygen How? Why? 2. Well fitting mask 3. ± Propped up position for obese pt 4. Correct duration  How long to preoxygenate to adequately preoy pt 1. 3-5 minutes 2. 3-5 vital capacity > for - emergency ↳ fetal brady cord eg : prolapse breaths , take deep breath in & out >- vital capacity thisno fomsample - get line monts are O2 from 16% to 80 % faction of expired go 3. Until FEO2 > 80% , standard to def > - gold adequate preoxygenation line -sample 16 % to 80% wait for FEU2 go from Preoxygenation to prolony time before pt desat What? How? Why?  Ventilate air in 8 out lungs - ensure can go - hold mask , breathing two General Anesthesia : Steps Intubate- by using breathing tube # cant intubate , cant ventilater a N/gas Preoxygenation process to put ↑ to ensure we are able to Induction agent ± volatile agent to pt sleep artificially ventilate lung GASR- for stable pt GAIPDU before paralysing Spontaneous respiration Test ventilation to test if we can ventilate pt , paralyse pt Hold mask / LMA Muscle relaxation if not if we can intubated not ↓ how to know if tube is in the lungs ? langed mask airway end tidal (O2/capnogram Intubation air entry · chest rise vapor from mask Confirm that airway is secured Stabilise vital signs Positioning & commencement of surgery Dr Jacynta Jayaram General Anesthesia Preoxygenation Induction agent ± volatile agent Spontaneous respiration Test ventilation Hold mask / LMA Muscle relaxation Intubation wont hear stomach sound on auscultation Confirm that airway is secured Stabilise vital signs Positioning & commencement of surgery Dr Jacynta Jayaram General Anesthesia Preoxygenation Induction agent ± volatile agent Spontaneous respiration Test ventilation Hold mask / LMA Muscle relaxation Intubation Confirm that airway is secured Stabilise vital signs Positioning & commencement of surgery Dr Jacynta Jayaram Regional Anesthesia Administration of regional anesthesia Monitoring of vital signs Assessing blockade Stabilization of vital signs Positioning & commencement of surgery Dr Jacynta Jayaram Rapid Sequence Induction IRSI) Anesthetic technique designed to facilitate rapid tracheal Ist-cic intubation in patients with high risk of aspiration 2nd nightmare - Induction Agent Render patient Facilitate emergent + Unconscious & Neuromuscular Tracheal intubation flaccid Blocking agent Dr Jacynta Jayaram  complication : severe chemical preumonitis - When is the Patient at Risk of Aspiration? hypoxic-ischemic encephalopathy - complication RISK OF LOSS OF ASPIRATION AIRWAY IS CONSCIOUSNESS ↓ SECURED pathologically/iatrogenic RSI shorten the time to minimize riskaf aspiration  Who is at Risk of Aspiration? Full stomach – Emergency surgery, inadequate fasting time, GI obstruction Delayed gastric emptying – Recent trauma, opiods, pregnancy Incompetent LES – Hiatus hernia, recurrent regurgitation, dyspepsia, prev upper GI surgery, pregnancy Esophageal diseases – Prev GI surgery, Ca Increased Abd pressure – Morbid obesity, pregnancy, Ldone under spinal epidial not GA by risk of aspiration if use GA , use RSI Dr Jacynta Jayaram Sellick’s Maneuver (Cricoid Pressure) Endotracheal Intubation  1. Preparation 2. Preoxygenation 3. Premedication Steps of RSI 5. Positioning (7P’s) 4. Paralysis w Induction 6. Placement of tube 7. Post intubation management General Anesthesia : RSI Acid reflux prophylaxis Preoxygenation Induction agent ± volatile agent Rapid onset propofol , thiopentine don't use Test ventilationINot done in RSI , air go to stomach 4 ↑ Spontaneous respiration aspiration risk of Cricoid pressure shape O divoid to prevent (compress esophagus on in aspiration Muscle relaxation I Rapid onset stomach Hold mask / LMA - Near Simultaneous L to minimise time btw Loc & intubation Intubation Definitive airway Lendotracheal tubel tracheostomy to prevent stomach content enter lung Confirm that airway is secured Stabilise vital signs Positioning & commencement of surgery Dr Jacynta Jayaram Pediatric Anesthesia lot of secretion don't went to poke again instead so give inhalation rgases vInhalation vs IV induction vParental presence vSpecial consideration to Ø Drug dosages Ø Temperature ↑ surface ratio area : vol , loss heat faster Ø Fasting times, blood glucose Ø Fluids Ø Equipment vSmaller reserves vHigher vagal tone vagal tune dominant parasym , dev first vFrequent URTIs don't want to into infection to lower part Dr Jacynta Jayaram Methods of General Anesthetic Administration ↑ IVA-total intravenous anaesthesia Induction vIntravenous vs Inhalation Maintenance vIntravenous vs Inhalation Dr Jacynta Jayaram Next Class Lecture : Pre-operative assessment & management CSL : Airway Management 1. Please read the provided material Skill lab manual Handouts Video links Guidelines 2. Ensure professional appearance White coat Grooming Attire Thank You Any Questions? Dr Jacynta Jayaram Next Class Lecture : Pre-operative assessment & management TBL : Intra-operative management 1. Please read the provided material 2. Be prepared for individual & group readiness assessment 3. Take note of the group seating arrangements as sent to the group leader