Anaesthetics Fundamentals Vocabulary

Getting Up to Speed: Introduction, Documentation, and Speciality Foundations

  • Anaesthetics 101 and the Ladder of Intervention

    • The term ‘anaesthetic’ is derived from the Greek for ‘loss of sensation.’
    • Practical anaesthesia is conceptualised as a ladder where each rung requires increasing airway support:
      1. Local Anaesthesia: Used to numb a specific procedural site. This can be performed by a surgeon independently.
      2. Regional Anaesthesia (Nerve Blocks): Local anaesthetic is injected near a nerve or plexus to anaesthetise a body part. It can be used alone or for perioperative analgesia alongside general anaesthesia.
      3. Neuraxial Anaesthesia: Involves injections into the back.
        • Spinal Anaesthesia: A needle passes between lumbar vertebrae into the subarachnoid space; the needle is removed after drug injection. Used for abdomen, pelvis, and leg procedures.
        • Epidural Anaesthesia: A small catheter is placed into the epidural space, allowing for continuous infusions or boluses over a longer timeframe.
      4. Sedation: Administered intravenously (IV) for anxiolysis. It requires careful titration to achieve benefits without causing respiratory depression.
      5. General Anaesthesia (GA): The patient is unconscious. Techniques vary by airway type and induction sequence.

  • GA Airway Types and Definitions

    • Facemask: Used for very short procedures.
    • Supraglottic Airway Device (SAD): Includes devices like Laryngeal Mask Airways (LMAs) and i-gels. These sit above the vocal cords and do not reliably protect against aspiration; they are not considered a ‘definitive’ airway.
    • Endotracheal Tube (ETT): Features an inflatable balloon below the vocal cords. Considered a definitive airway as it protects against aspiration.

  • Induction Sequences

    • Delayed Sequence Induction (DSI): A slower process used for elective patients with low risk of regurgitation or aspiration.
      • Regurgitation: The passive movement of gastric contents into the pharynx.
      • Aspiration: The entry of liquid or solid material (e.g., gastric contents) into the trachea and lungs.
    • Rapid Sequence Induction (RSI): Used in emergencies or when there is a risk of regurgitation between losing consciousness and airway placement. The aim is to minimize the time between unconsciousness and ETT placement.

  • Logbook Maintenance and the LLP

    • Trainees must maintain a logbook via the Royal College of Anaesthetists’ Lifelong Learning Platform (LLP).
    • ASA Physical Status Classification Score: Used to judge fitness for surgery.
      • ASA 1: Fit/well, non-smoker, no alcohol.
      • ASA 2: Mild systemic disease, well-controlled (e.g., stable asthma).
      • ASA 3: Severe systemic disease (e.g., stable angina).
      • ASA 4: Severe systemic disease that is a constant threat to life (e.g., unstable angina).
      • ASA 5: Moribund, not expected to survive without the operation (e.g., ruptured aortic aneurysm).
      • ASA 6: Brain-dead organ donor.
      • Suffix ‘E’: Denotes emergency surgery.
    • NCEPOD Priority Classification:
      1. Priority 1 (Immediate): Life, limb, or organ-threatening; target time to theatre is minutes.
      2. Priority 2 (Urgent): Conditions threatening life/limb survival; target time is hours.
      3. Priority 3 (Expedited): Early intervention needed; target time is days.
      4. Priority 4 (Elective): All elective surgeries.
    • Mode of Anaesthesia Terms:
      • SV (Spontaneous Ventilation): Patient maintains their own respiratory effort. Includes assisted spontaneous ventilation (Pressure Support).
      • IPPV (Invasive Positive Pressure Ventilation): Controlled ventilation where the machine breathes for the patient due to agents causing respiratory depression or muscle relaxants paralyzing respiratory muscles.

  • The Initial Assessment of Competence (IAC)

    • Passing the IAC is the milestone for being ready to work on-call.
    • Novice requirements: maintain a logbook, personal reflections, simulation sessions (‘Skills and Drills’), and multiple trainer reports (MTR).
    • EPAs (Entrustable Professional Activities):
      • EPA 1: Ability to perform an anaesthetic pre-operative assessment.
      • EPA 2: Ability to provide GA for ASA 1/2 patients for uncomplicated surgery.
    • SLE Supervision Levels:
      • Level 1: Direct supervisor physically present.
      • Level 2a: Supervisor in theatre suite; monitoring at regular intervals.
      • Level 2b: Supervisor within hospital; available for prompt direction.
      • Level 3: Supervisor on-call from home.
      • Level 4: Manage independently.

  • Essential Anaesthetic Apps and Wellbeing

    • QRH (Quick Reference Handbook): Compiled by the AAGBI for anaesthetic emergencies.
    • iResus: Reference for resuscitation Council guidelines.
    • SOBA: Society for Obesity and Bariatric Anaesthesia; contains dose calculators for high BMI patients.
    • Pedi Help: Aid for paediatric equipment sizing and dosing.
    • Induction: Extension and bleep numbers for specific hospitals.
    • Wellbeing: Suicide rates in anaesthetics are higher than other specialties; ‘sterile flightdeck’ principles apply to critical phases.

Pre-Operative Assessment: Systematic Evaluation and Risk Scoring

  • Goals of Pre-Operative Assessment

    1. Collect relevant patient information.
    2. Explain the anaesthetic and potential risks to the patient.
    3. Identify and highlight factors that confer increased anaesthetic risk to seniors.

  • Systematic Review of Observations and Investigations

    • Uncontrolled Hypertension: A systolic blood pressure (SBP) >180 mmHg> 180\,\text{mmHg} or a diastolic blood pressure (DBP) >110 mmHg> 110\,\text{mmHg} is a cause to postpone elective surgery.
    • Diabetes: Check HbA1c. An HbA1c≥69 mmol/mol\text{HbA1c} \geq 69\,\text{mmol/mol} may be a reason to postpone surgery for better glycemic control.
    • Baseline Measurements: Weight, height, BMI, and baseline heart rate (HR) are vital for drug dosing.
    • Previous Cormack-Lehane Grading: Found in old charts; describes the glottis visibility during laryngoscopy (11 to 44 scale).

  • Anaesthetic History and Red Flags

    • Malignant Hyperthermia (MH): A life-threatening hypermetabolic reaction to volatile agents or suxamethonium. It is an autosomal dominant genetic condition.
    • Suxamethonium Apnoea: Slow metabolism of the muscle relaxant suxamethonium; usually an autosomal recessive condition.
    • At-Risk Conditions:
      • CV: MI in the last 1212 months is usually a reason to postpone; risk of death is 50×50\times higher than baseline in the first month following an MI.
      • Resp: Interstitial Lung Disease (ILD) makes ventilation difficult due to fibrosed lungs.
      • Neuro: Ankylosing Spondylitis and Rheumatoid Arthritis (RA) can cause atlanto-occipital joint extension limits; RA and Down’s Syndrome carry risks of atlantoaxial instability.
      • NM: Muscular dystrophies and myasthenia gravis contraindicate certain drugs.
      • Burns: Suxamethonium is contraindicated from 2424 hours to 1818 months post-injury due to potassium release.
      • Spinal Injury: Suxamethonium contraindicated from 4848 hours to 99 months post-injury.

  • Pre-Operative Starvation Guidelines

    • Food: No food for 66 hours before surgery (includes milky drinks/gum).
    • Drink: Clear fluids (water, black tea/coffee, weak squash) allowed until 22 hours before surgery.
    • Note: GLP-1 agonists (e.g., Wegovy, Ozempic) delay gastric emptying; food may remain despite a 66-hour fast.

  • Airway Assessment (BONES and LEMON)

    • BONES (Predictors of Difficult Facemask Ventilation): Beard, Obesity, No teeth (edentulous), Elderly (>55> 55), Snoring.
    • LEMON (Predictors of Difficult Intubation):
      • L: Look externally (short neck, obesity, deformity).
      • E: Evaluate 3-3-2 Rule:
        • 33 fingers between the incisors (mouth opening).
        • 33 fingers between hyoid bone and mentum (hyomental distance).
        • 22 fingers between thyroid notch and neck/mandible junction.
      • M: Mallampati Score: Performed sitting up, max mouth opening/tongue protrusion, no phonation.
        • Class 1: Full view of soft palate, fauces, uvula, and pillars.
        • Class 2: View of soft palate, fauces, and uvula.
        • Class 3: View of soft palate and base of uvula.
        • Class 4: Soft palate not visible at all.
        • Sensitivity: Moderate-high (50−80%50-80\%); Positive Predictive Value: Low (5%5\%).
      • O: Obstruction (Stridor, drooling, submandibular abscess, bilateral anterior mandible fractures).
      • N: Neck Mobility: Warning sign of Delilkan (index fingers on chin and occipital tuberosity; chin should lift higher).
    • Additional Measurements:
      • Thyromental Distance (TMD): <7 cm< 7\,\text{cm} indicates difficult intubation.
      • Sternomental Distance (SMD): <12.5 cm< 12.5\,\text{cm} indicates difficulty.
    • **Jaw Pro

I'm unable to provide drawings directly, but I can describe concepts or processes in anaesthetics that can be illustrated. For example, the hierarchy of anaesthesia types (Local, Regional, Neuraxial, Sedation, General) could be visualized in a ladder format, showing the increasing complexity and level of airway support required. If you have specific concepts in mind, I can help describe them for visual representation.