Anaesthetics: Principles and pharmacology, conduct of anaesthesia and critical care Flashcards
What does an anaesthetist do?
○ Pre-op Assessment & Care ○ Critical Care / Intensive Care ○ Pain Management ○ Anaesthesia ○ Post-operative care
What is the process of anaesthetics?
- Pre-operative Assessment
- Preparation
- Induction
- Maintenance
- Emergence
- Recovery
- Post-operative care and pain management
What happens in preperation for anaesthetics?
- Planning
- Right patient, right operation
- Right (or left) side…..
- Pre-medication
- Right equipment, right personnel
- Drugs drawn up
- IV access
- Monitoring
What happens during induction of anaesthetics?
- Quietness
□ In the UK, often in a separate, dedicated anaesthetic room - Gas or IV Agent
□ IV induction ® Propofol, Thiopentone + others ® Rapid ® One “arm-brain” circulation ~ 20s ® No obvious planes ® Easy to overdose ® Generally rapid loss of airway reflexes ® Apnoea is very common
□ Gas induction ® Sevoflurane (Halothane) ® Common in young children ® Slow ® Considerably more obvious “planes” of anaesthesia
What happens in maintenance of anaestetics?
- Careful monitoring of conciousness level
- Airway maintenance
- Monitoring
How does soemone monitor coniousness level?
□ Loss of Verbal Contact □ Movement □ Respiratory Pattern □ Processed EEG □ “Stages” or “planes” of anaesthesia
How does someone maintain airways?
□ Always required in general anaesthesia
□ Simple manoeuvres
□ Head Tilt / Chin Lift / Jaw Thrust…
□ Simple apparatus
® Face Mask
◊ Identical to those used in Resuscitation ◊ Contoured to face to allow a gas-tight seal
◊ Sizes from neonatal - large adult
◊ Technique involves lifting the face into ◊ Standard connector
® Oropharyngeal (“Guedel”) Airway ◊ Developed by Guedel in the US ◊ Rigid plastic ◊ Only tolerated by an unconscious patient ◊ Insertion in a ‘light’ patient may cause vomiting or laryngospasm
® (Nasopharyngeal Airway)
® Laryngeal Mask Airway ◊ Cuffed tube with ‘mask’ sitting over glottis ◊ Maintains, but does not protect the airway ◊ Sizes for adults and children
How is a patient under anaesthetics monitored?
□ Basic “minimum” monitoring ® SpO2, ECG, NIBP, FiO2, ETCO2 □ Respiratory parameters □ Agent monitoring □ Temperature, Urine Output, NMJ □ Invasive Venous / Arterial Monitoring □ Processed EEG □ VENTILATOR DISCONNECT □ The anaesthetist is the best monitor...
What happens during emergence?
- i-gel®
- “2nd generation” LMA
- (Relatively) Easy insertion
- Does NOT protect from aspiration
- Landing is as hazardous as take-off
- Muscle relaxation reversed
- Anaesthetic agents off
- Resumption of spontaneous respiration
- Return of airway reflexes / control
- Extubating
- Can be very quick or very, very slow
What happens during recovery?
- A dedicated area with trained staff
- Many patients have not yet regained consciousness or AIRWAY CONTROL
- Continuing responsibility of anaesthetist
- Problems with A, B, C
- Pain control
- Post-operative Nausea & Vomiting
- Set criteria for discharge back to ward
- Post-operative Care and Pain Management
What are the planes of anaesthesia?
○ Analgesia / Sedation ○ Excitation ○ Anaesthesia: Light ---> Deep ○ Overdose Or ○ Sleepy / Excited / Anaesthetised / …..
What are the airway coplications?
- Obstruction
- Aspiration
What is the difference between maintaining or protecting an airway?
○ The airway is maintained if it is open and unobstructed
○ Only a cuffed tube in the trachea protects the airway from contamination
What is endotracheal intubation?
○ Placement of a cuffed tube in the trachea
○ Oral route most commonly used
○ Laryngeal reflexes must be abolished
○ Classic method uses laryngoscope, muscle relaxant, “sniffing the morning air” position
○ Also possible in the awake patient using local anaesthesia and fibre-optic scope
Why intubate?
○ Protect airway from gastric contents
- e.g. full stomach in an unfasted emergency patient
○ Need for muscle relaxation, therefor artificial ventilation
- e.g. laparotomy (muscle relaxants are not selective!)
○ Shared airway with risk of blood contamination
- e.g. tonsillectomy in ENT
○ Need for tight control of blood gases
- especially CO2 levels in Neurosurgery
○ Restricted access to airway
- e.g. Maxillo-facial surgery
What risks are there to an unconcious patient?
○ “Airway, Airway, Airway” ○ Temperature ○ Loss of other protective reflexes - e.g. corneal, joint position ○ Venous thromboembolism risk ○ Consent & Identification ○ Pressure areas
What type of anaesthetic drugs do you get?
○ Inhalational anaesthetics ○ Intravenous anaesthetics ○ Muscle relaxants ○ Local anaesthetics ○ Analgesics
