Conduct of Anaesthesia Flashcards
What are the phases of the process of anaesthesia?
Pre-operative assessment Preparation Induction Maintenance Emergence Recovery Post-operative care and management
What is involved in the preparation for anaesthesia?
Planning Right patient, right operation, right side Pre-medication Right equipment and personnel Drugs drawn up IV access gained Monitoring
What is involved in the induction of anaesthesia?
Quietness
Gas or IV agent
Careful monitoring of conscious level
Airway maintenance
What are some of the drugs used in IV induction?
Propofol
Thiopentone
What are the features of IV induction?
Rapid - one arm-brain circulation around 20 seconds
No obvious planes
Easy to overdose
Generally rapid loss of airway reflexes
Apnoea common
Airway reflexes weak off quite quickly allowing quick control of airways by anaesthetists
What are the features of gas induction?
Sevoflurane (Halothane) used
Common in young children
Slow
Considerably more planes of anaesthesia
What are the planes of anaesthesia?
Analgesia/sedation Excitation Anaesthesia (light-deep) Overdose Sleepy/excited/anaesthetised
How is conscious level monitored?
Loss of verbal contact Movement Respiratory pattern Processed EEG Stages/planes of anaesthesia
When is airway maintenance required?
Always required in general anaesthesia
How is airway maintenance achieved?
Simple manoeuvres e.g. head tilt, chin lift, jaw thrust
Triple airway manoeuvre
Face mask
Oropharyngeal or nasopharyngeal airway
What are the features of the oropharyngeal airway?
Developed by Guedel in US
Rigid plastic
Only tolerated by unconscious patient
Insertion in a light patient may cause vomiting or laryngospasm
How is more advanced airway management achieved?
Using laryngeal mask airway - cuffed tube with mask sitting over the glottis
What are the possible causes of airway obstruction?
Foreign body (almost always this) Ineffective triple airway manoeuvre Airway device malposition or kinking Laryngospasm Forced reflex adduction of vocal cords Caused by airway stimulation in light planes of anaesthesia
Why might anaesthesia result in aspiration?
Anaesthesia causes loss of airway reflexes e.g. cough, gag, swallow
What is the difference between airway maintenance and protecting?
Airway is maintained if it is open and obstructed
Only a cuffed tube in the trachea protects the airway from contamination
What are the features of endotracheal intubation?
Placement of cuffed tube in trachea
Oral route most commonly used
Laryngeal reflexes must be abolished
Why might intubation be necessary?
Protect airway from gastric contents
Need for muscle relaxation and artificial ventilation
Shared airway with risk of blood contamination
Need for tight control of blood gases
Restricted access to airway
What are the risks to the unconscious patient?
Airway Temperature Loss of protective reflexes e.g. corneal, joint position Venous thromboembolism Consent and identification Pressure areas
What are the positions which might be used for procedures requiring anaesthetic?
Supine Lithotomy Prone Lying on side Sitting
What are the features of continuing anaesthesia?
Care of unconscious patient Muscle relaxation, analgesia Monitoring and physiological support Fluid management Documentation and recording Induction agents wear off Maintenance with IV, inhalation agent or both Self or artificial ventilation Balanced technique Analgesia Gas supply
What are the features of monitoring anaesthesia?
Basic minimum monitoring - SpO2, ECG, non-invasive BP, FiO2, ETCO2
Respiratory parameters - tidal volume, airway pressures
Agent monitoring
Temperature, urine output, NMJ
Invasive venous/arterial monitoring
Processed EEG
Ventilatory disconnect
What are the possible anaesthetic complications?
Airway Breathing Circulation Related to techniques or position Awareness
What are the risk factors for awareness?
Paralysed and ventilated Previous episode of awareness Chronic CNS depressant use Cardiac surgery Major trauma GA C-section
What are the features of emergence/awakening?
Muscle relaxation reversed Anaesthetic agents switched off Resumption of spontaneous respiration Wait for return of airway reflexes/control Extubation Can be very quick or very slow
What are the features of recovery?
Dedicated area with trained staff
Many patients not yet regained consciousness or airway control
Continuing responsibility of anaesthetist
Problems with A, B, C
Pain control
Post-operative nausea and vomiting
Set criteria for discharge back to ward
