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ALL YOU NEED TO KNOW ABOUT ANAESTHETICS AND PERIOPERATIVE CARE Tutor: Rama Aubeeluck Here’s what we do: ■ Weekly tutorials open to all! 18:00 every Thursday ■ Focussed on core presentations and If you’re new here… teaching diagnostic technique from a clinical perspective ■ Reviewed by doctors to ensure W elcome to accuracy T eaching ■ We’ll keep you updated about our Things! upcoming events via email and groupchats!T opics we will cover today ● Pre-op assessment ● Basics of anaesthesia (placement heavy) ● Post op prescribing (OSCE heavy)Why is peri-op care and anaesthetics important? A huge portion of patients in hospital will have surgery - as an F1 / F2 you will most likely have to prep this patient This will include examining the patient, taking a good history, prescribing relevant medication and stopping harmful medication The same applies for when the patient leaves surgery - the post-op patient…(we will briefly cover this today)How confident are you about this topic? 1. Its not looking good brev 3. Meh too sure 4. I know most things 5. Just here to brush up on things I knowPre-operative assessment What might we do to prepare a patient for surgery?Pre-operative assessment Help optimise patients ● Bedside: cardio + resp exam, full set of obs, ECG ● Bloods: FBC, U&E, HbA1c, G+S ● Other: CPET testing ● MRSA testingASA classificationASA classification - importance 1. Risk stratification - higher ASA indicates greater risk of peri-op complications, so needs greater planning and level of input from senior anaesthetists. In the anaesthetic environment, this may need more careful positioning, long pre-oxygenation, and choice of medication, and need for more monitoring in surgery 2. Predicts outcomes 3. Communication tool - gives a common language across surgical, anaesthetic and periop teamsModifying medicationModifying medication Mnemonic: I LACK OP Insulin: VRII Lithium: Day before is stopped the day before)s. Aspirin and clopi (7 days), Warfarin (5 days and bridged with LMWH, which C: COCP/HRT (4 weeks before) K: K+ sparing diuretics O: Oral hypoglycaemics P: Perindropril and other ACE-IModifying medication (diabetes)Modifying medication (diabetes) Why are these drugs specifically stopped? Hint: Think about side effect profile…Modifying medication (diabetes) ● These drugs are hypoglycaemic agents ● All of these drugs have different mechanism of actions but can cause hypoglycaemia ● This should be avoided in surgery and so stopping these drugs and substituting where necessary is important ● Metformin also carries the risk of lactic acidosis ● SGLT-2 inhibitors also carry the risk of euglycaemic DKAStopping fluids and food General surgical rules are to stop patients from drinking 2 hours before surgery and to stop eating 6 hours before surgery Why is this?Stopping fluids and food General surgical rules are to stop patients from drinking 2 hours before surgery and to stop eating 6 hours before surgery Why is this? Reflux prevention! Airway management (we will come to this) has associated risks that need to be managed - this is one of the methods we use in clinical practiceAnaesthetics - what is the triad? 1. Hyponosis (unconciousness): Loss of awareness and amnesia 2. Analgesia: pain relief, suppresses the nociceptive response to surgery 3. Muscle relaxtion: allows for intubation and surgical accessBasics of anaesthetics - hypnosis Causes a loss of awareness and analgesia IV options 1. Propofol 2. Ketamine 3. Sodium theopentone 4. Etimodate Gas options 1. Halogenated hydrocarbons: sevoflurna, isofluane, desoflurane 2. Nitrous oxideBasics of anaesthetics - hypnosis Options for putting the patient to sleep 1. Use IV only (TIVA - total intravenous anaesthesia) 2. Use gas only 3. A mix of both Most commonly, the main method is using IV medication to put the patient to sleep (induction) and then using gas to keep the patient asleepBasics of anaesthetics - hypnosis IV Drugs Propofol ● Mechanism of action: GABA agonist (activates inhibitory centers) ● Cons: Painful injection, myocardial depressiondly metabolised Ketamine ● Mechanism of action: Non competitive NMDA antagonist, blocking glutamate, (main excitatory NT in the brain) ● Pros: strong analgesia, little myocardial depression (favoured in RSI)Basics of anaesthetics - hypnosis IV continued Sodium theopentone ● Cons: Myocardial depression, laryngospasm, cannot use for maintenance (only induction) Etimodate ● Mechanism of action: Activates GABA ● Pros: Very safe for cardiac system ● Cons: No analgesia, vomiting post-opBasics of anaesthetics - hypnosis Inhaled options Sevo/des/isoflurane ● Mechanism of action: Enhances GABA ● Cons: Myocardial depression, malignant hyperthermia, halothane is hepatotoxic Nitrous oxide ● Mechanism of action: Inhibits NMDA receptors ● Cons: Can diffuse into gas filled compartments, causing increased pressureBasics of anaesthetics - hypnosis Medications to assist with GA ● Benzodiazepines e.g. midazolam: relaxes muscles and anxiety ● Opiates: reduce pain ● Alpha-2-agonists (clonidine): sedative and painBasics of anaesthesia - analgesia 2 aspects to pain ● and quality) of pain (e.g. sharp, burning, throbbing) - this lets you know where pain is. Travels via spinothalamic tract -> somatosensory cortex ● Affective: Actual feeling of pain (heat, pressure, chemical are the main inputs). Drives the emotional and behavioural reaction e.g. avoidance, fear. Travels via the limbic system, anterior cingulate cortexBasics of anaesthesia - analgesia Central analgesia (targets emotional/ affective + higher sensory) Opioids ● MOA: µ-receptor agonists in brain and spinal cord ● Blunts sensory and affective aspects Ketamine ● MOA: NMDA antagonist ● Prevents chronic pain Paracetamol ● MOA: Inhibits COX (potentially) ● Mild to moderate pain, good adjunct to opioidsBasics of anaesthesia - analgesia Spinal / peripheral analgesia (targets sensory input before it reaches the brain) Local anaesthetics (e.g. Lidocaine) ● MOA: Blocks VG NA+ channels -> stops nerve conduction ● Use for regional blocks, spinals, epidurals NSAIDs ● MOA: Inhibit COX → ↓ prostaglandin synthesis → ↓ peripheral sensitisation ● Reduces inflammation and nociceptor activationBasics of anaesthesia - analgesia Multimodal Analgesia = Combining Drugs ● Hits different parts of the pain pathway ● Allows for opioid-sparing effect (less side effects) ● Common combo: Paracetamol + NSAID + Opioid ● Add ketamine or regional block if severeAnaesthetic pharmacology - muscle relaxation Aim: to reduce muscle tone, allowing for easy intubation , reduce anaesthetic requirement and stop patient movement under anaesthesia General physiology behind the drugs: acetylcholine is released at the neuromuscular junction (NMJ) and binds to nicotinic receptors on skeletal muscle → opens ion channels → depolarisation → muscle contraction Drugs therefore work to stop this binding of Ach to nictonic receptors 2 main types ● Depolarising ● Non-depolorisingAnaesthetic pharmacology - muscle relaxation Depolarising muscle relaxants Drug: Suxamethonium ● Mimics Ach and causes so much depolarisation to the point that it cannot repolarise (you will see fasciculations when this happens) ● Rapid onset, short duration ● Used in rapid sequence induction (1st line) ● Effects wear off naturally (no reversal agent) ● Side effects: Fasciculations, hyperkalaemia, malignant hyperthermia ● CI: Raised ICP (so avoid in eye injuries or glaucoma)Anaesthetic pharmacology - muscle relaxation Non-depolarising ● Mechanism: competitive antagonists of nicotinic Ach receptors Drugs: rocuronium, atracurium, pancuronium ● Rocuronium is reversed with sugammadex ● Atracurium is reversed with Neostigmine (which comes with antimuscarinic side effects - blurred vision, confusion, chest pain, bradycardia etc.)Anaesthetic equipment - airway devices Basic airway adjuncts 1. Oropharyngeal airway (Guedel) ● Keeps tongue of posterior pharynx ● Use in unconscious patients with no gag reflex ● OSCE: you should know how to insert one! 2. Nasopharyngeal airway ● Use in semi-conscious patients ● CI: Basal skull fractureAnaesthetic equipment - airway devices Supraglottic airway devices (sits on top of the pharynx) 1. Laryngeal mask airway ● Good for short surgeries or difficult airways 2. i-Gel ● Second gen LMA ● Allows gastric drainage ● More commonly seen in practice now than an LMAAnaesthetic equipment - airway devices Invasive airway devices 1. Endotracheal tube (ETT) ● Cuffed tube inserted through vocal cords ● Gives full airway protection (but may need NMJ blockers) ● Monitor CO2 (capnography) due to risk of oesophageal intubation 2. Tracheostomy ● More of an ITU thingAnaesthetic equipment - other things you might see ● Arterial lines ● Central lines ● (Hickman) Tunnelled lines ● PICC linesIntubation vs putting a patient to sleep These are NOT the same thing ● Putting a patient to sleep: patient becomes unresponsive and unconscious due to anaesthetic agents ● Intubation: securing the airway - using an ET tube specifically to maintainthe airway and deliver oxygen / other gas. Using an igel or LMA does not count as intubation. ETT normally requires muscle paralysis (not all surgeries use this), and is done in surgeries with a higher aspiration risk, longer surgeries etc. The anaesthetic machine Component Function Ventilator Control Panel Sets mechanical ventilation (rate, volume, PEEP). Bellows / Housing Moves with each breath; shows ventilation status. Bag Arm Switches between manual and ventilator modes. Absorber System Directs exhaled gas through CO₂ absorber. CO₂ Canister Removes CO₂ via soda lime. Insp/Exp Ports One-way valves for gas flow to/from patient. Gas Flowmeters Control flow of O₂, air, N₂O. Vaporizer Adds volatile agent to fresh gas. O₂ Flush Delivers high-flow 100% O₂; bypasses vaporizer. Auxiliary O₂ Provides O₂ via face mask/nasal cannula.Putting it all together ● Patient re-consents for surgery with surgeon and anaesthetist ● Cannula inserted ● Patient is pre-oxygenated with a mask to 99-100% O2 ● Hypnosis agent delivered (patient falls asleep) ● Bag-valve mask ventilation used as patient stops breathing independently ● Pain relief delivered (trauma response blunted) ● NMJ blocker given if needed ● Airway device inserted and machine ventilation is turned on ● Surgery beginsA 42-year-old woman presents to A&E with severe abdominal pain andvomiting. She is alert but distressed, with a distended abdomen. She requires emergency surgery. The anaesthetist is planning a rapid sequence induction (RSI). Which of the following is the most appropriate combination of drugs for induction? A. Midazolam and atracurium B. Propofol and rocuronium C. Etomidate and vecuronium D. Ketamine and suxamethonium E. Thiopentone and cisatracuriumA 42-year-old woman presents to A&E with severe abdominal pain and vomiting. She is alert but distressed, with a distended abdomen. She requires emergency surgery. The anaesthetist is planning a rapid sequence induction (RSI). Which of the following is the most appropriate combination of drugs for induction? A. Midazolam and atracurium B. Propofol and rocuronium C. Etomidate and vecuronium D. Ketamine and suxamethonium E. Thiopentone and cisatracuriumRapid sequence induction ● Technique used to secure the airway in patients with a highrisk of aspiration: trauma, bowel obstruction, GORD, Key steps ● Pre-oxygenate ● Medication: 3-2-1 rule (3 mg/kg ketamine [induction agent], 2 mg/kg rocuronium [NMJ blocker], 1 mcg/kg fentanyl [blunts sympathetic response]) ● Cricoid pressure and bed elevation: reduces the risk of aspiration ● Immediate intubation after paralysis Malignant hyperthermia Inherited condition (autosomal dominant fashion), causing mutations in ryanodine receptor in sarcoplasmic reticulum Causes: Halothane (gas anaesthetic), suxamethonium (depolarising NMJ blocker), antipsychotics Normally: Normally, an action potential causes calcium release from the SR via ryanodine receptors, which allows for actin-myosin cross-bridging -> muscle contraction. Then, the calcium is reabsorbed. In MH: Uncontrolled Ca2+ release, and uncontrolled resorption -> excessive contractions Features: Pyrexia (due to ATP hydrolysis), tachycardia, muscle rigidity (uncontrolled contraction), raised CO2 Management: Dantrolene - blocks Ca2+ release from the sarcoplasmic reticulumA note on NMJ blockers essential.axants are invaluable in certain surgeries but are avoided when not With the use of supraglottic airway devices and volatile or TIVA-based anaesthesia, many procedures — especially short ones — can be safely done without neuromuscular blockade. This reduces the risk of residual paralysis, speeds up recovery, and simplifies monitoring Rocuronium also has an anaphylaxis rate of 1/2500 and is not tested for pre-surgeryThe post op patient…. What is important?The post op patient…. What is important? ● Monitoring for any complications: obs, AVPU/GCS, surgical site ● Providing adequate analgesia and fluids ● Optimising recovery: early mobilisation, DVT prophylaxis, physio ● Preparing for discharge: ADLs independently, passing urine/bowel motion, adequate pain controlBasic complications post op Complications 🫁 Respiratory: Atelectasis, pneumonia, aspiration 🩸 Cardiovascular: Hypotension, hypertension, MI, DVT/PE 🧠 Neurological: Delirium, stroke, prolonged sedation 🩺 Surgical Site: Bleeding, infection, dehiscence ⚙ Systemic: UTI, AKI, electrolyte imbalance 🍽 GI: Nausea, vomiting, ileus, constipation + Any complications from the surgery itself: failure, perforation, specificissuesPost operative pyrexia Any potential causes?Post operative pyrexia Any potential causes? Mnemonic (5 W’s) ● Wind: pneumonia (1-2 days) ● Water: UTI (3 days) ● Wound: Wound infection (5 days) ● Walking: VTE (5 days+) ● Wonder drugs: Drug reactions (unlikely to have no time limit)Prescribing in the post op patient What common drugs would you be expected to prescribe in a post-op patient as an F1 doctor?Prescribing in the post op patient What common drugs would you be expected to prescribe in a post-op patient as an F1 doctor? ● Fluids (maintenance and replacement) ● Pain relief (WHO pain ladder) + adjuncts to treat potential complications ● VTE prophylaxis ● Anti-sickness medication ● Antibiotics (if required by local protocol) ● Diabetic medication (insulin sliding scale) ● OxygenFluids Main indications for fluids: - Replacement (e.g., vomiting and diarrhoea)) - Maintenance (e.g., nil by mouth due to bowel obstruction) Patients will be NBM post surgery so will need maintenance fluids, whichFluids - maintenance prescription How confident are you in this topic? 2. I know some stuff 3. Have done it a couple of times 4. Very comfortableFluids - maintenance 65 kg female with no hydration deficit requires maintenance fluid prescription prescribed. What specific fluids - and at what rate - does she need for the next 24 hrs?Fluid requirements Water 25-30ml/kg/day for any adult standard requirements Knowing the different types of fluids Sodium/Na 1-2 mmol/kg/day we can give to a patient will help you decide what to prescribe in a patient Chloride/ Cl 1-2 mmol/kg/day In the case of our patient, in the next 24 hours we need to prescribe: ● ~1625 to 1950ml (+- 20%) Potassium/ K 1 mmol/kg/day ● 65-130 mmol Na ● 65-130 mmol Cl ● 65 mmol K Glucose 50-100/day ● 50-100g glucoseFluids - main types Potassium is added to the bags - it does not come pre preparedSteps 1. Using weight of patient, work out requirements for the next 24 hours 2. Consider what fluids you will need to prescribe (use only 0.9% Sodium Chloride and 5% Dextrose) 3. give vs how many bags of 0.9% Sodium Chlorideratio tells you how many bags of 5% dextrose to 4. Ensure to add the right amount of potassium in a safe manner (no more than 10mmol/hour) 5. Write it up In this patient, we need to provide: ~1625 to 1950ml (+- 20%) ● 65-130 mmol Na, 65-130 mmol Cl, 65 mmol K, 50-100g glucose Bags come as 1000ml, 500ml, 250ml (sometimes). We can give this patient 2 litres of fluid as it is more or less in the upper limit. We know this patient will need 2 bags of 5% dextrose, so we can give: 1L 5% Dextrose, 500ml 5% dextrose, 500ml 0.9% Sodium Chloride, with 60 mmol potassium infused with these fluids, at a rate no more than 10 mmol/hour Does this fit our electrolyte requirements? This patient will receive: ● 77 mmol sodium , 77 mmol chlorine, 60 mmol potassium, 75g glucose This satisfies all requirements! So now we just need to write this up in a safe formatExamples to try ● 80kg with no extra requirements ● 70kg who is 10% dehydrated ● Have a look at paediatric maintenance fluid prescribing separately as this is done differently to adultsPain relief What protocol / system should we follow when prescribing pain relief?Pain relief - WHO pain ladder We follow this system to prescribe adequate pain relief - the ladder was developed for chronic pain and palliative care, but is now used for acute pain as well In post-op care, we usually go straight to the 3rd rung due to the severity of the pain Morphine + paracetamol is commonly given What issues can arrive from prescribing morphinePain relief - morphine Mechanism of action ● Opioid ● Blocks transmission of nociceptive signals Side effects of morphine ● Constipation (treatable) ● Nausea (treatable) ● Drowsiness (worse when starting but wears off) ● Confusion (monitor) ● Respiratory depression (monitor + control doses) What drugs would you prescribe to treat the constipation and nausuaDrugs to prescribe ● Morphine (pain), 10mg or 5mg if elderly, oral PRN ● Paracetamol (pain), 1g regular prescription ● Cyclizine (anti-emetic), 50mg PRN ● Senna (laxative), 7.5-15mg, once nightly, regular ● Consider omeprazole (cover for potential reflux), 20mg regular Use the BNF in your OSCE!Other things to consider ● Antibiotics (if required by local protocol) ● Oxygenic medication (insulin sliding scale)VTE prophylaxis ● Very very important in preventing DVTs and potential PEs -> do a VTE risk assessment ● Trust dependent - for UCL exams, give 40mg Enoxaparin SC. Easy to write under timed conditions ● As with senna, this is given at night time (patients are most immobile when asleep) ● Can co-prescribe this with TED stocks (write this in “additional information”Other things to read up on ● Post op ileus ● Post op N/V ● Delirium ● Urinary retention ● Atelectasis THANKS FOR W ATCHING! Tutor 1: Rama Aubeeluck Tutor 2: N/A Please fill out the feedback form on Medall and see you next week!