General Flashcards
List the pulmonary complications from multiple rib fractures
Atelectasis
Hypoxaemia/shunt
Pneumothorax
Haemothorax
Pneumonia
Respiratory failure requiring intubation
Hypercapnoea requiring NIV
How would you prevent pulmonary complications from mutliple rib fractures
Analgesia
Humidified oxygen
Saline nebulisers
Chest physiotherapy
Give the analgesic options for rib fractures
Paracetamol
NSAIDs
Opiates e.g. morphine either regular+PRN or PCA
Gabapentin/pregabalin
Ketamine
Pros: familiar, cost effective, does not require specifically trained staff (except PCA), adequate analgesia
Cons: side effects include N+V, constipation, delerium, regional provides better pain relief and fewer pulmonary complications than IV opiates
**
Regional anaesthesia**
Thoracic epidural
* Pros: bilateral analgesia, lower risk of LA toxicity than other thoracic blocks, remains gold standard for analgesia, reliable
* Cons: technically difficult (positioning difficulties), risk of dural puncture/spinal cord injury, hypotension, urinary retention, pt should be awake to warn of paraesthesia
Paravertebral block
* Pros: unlike epidural->no sympathetic block so less hypotension and urinary retention, pt can be sedated, effective analgesia
* Cons: unilateral, risk of pneumothorax, risk of epidural spread
Serratus plane block:
* Pros: superficial block, performed with patient supine (easier positioning esp. intubated pts), can be inserted in anticoagulated patients
* Cons: risk vascular puncture, pneumothorax, covers anterior 2/3rds of chest only, variable LA spread
Errector spinae block:
* Pros: good for anterior and posterior fractures, less risk of epidural spread than paravertebral, technically more simple than PVB+epi, spreads to ribs +3 above and +4 below
* Cons: relatively new so evidence lacking, unilateral block, may require multiple injections
What are the indications for surgical rib fixation
- 5 or more rib fractures with flail segment, esp if requires NIV or invasive ventilation
- Symptomatic non-union
- Severeley displaced ribs found during thoracotomy for another reason
Soft indications:
* Flail chest
* 3 or more displaced fractures
* over 65yrs
* chest wall deformity
* requires mechanical ventilation
* 25% volume loss on CXR
Indicators for difficult BVM
Impossible (inability to achieve lung movement and end tidal CO2 despite optimised efforts)
Difficult (leak, reduced chest rise, two handed technique, need for adjunct):
* DIFFMASK: age>45yrs, BMI>35, full beard, previous neck radiation
* Male
* OSA
* MP3-4
* Limited jaw protrusion
* Neck circumference>43cm
* Edentulous
Indicators for difficult intubation
- Small mouth opening
- Previous difficult intubation
- Neck irradiation
- Obesity
- Limited neck extension
- Neck circumference >43cm
- Retrognanthia
- TMD <6.5, SMD <12.5, MHD <4.5
- MP 3 or 4
Methods to optimise BVM ventilation
- Optimise operators position
- Optimise patient position of head and neck (head tilt, chin lift, jaw thrust, midline)
- Ensure jaw lifted to mask rather than mask pressed onto face
- Remove apparatus causing leak e.g. NG tube
- Four handed technique
- Adjuncts e.g. OPA
- Increase sedation/give paralysis
- Switch operator
- Shave
- Treat lung pathology e.g. bronchospasm
Grades of bone cement implantation syndrome
- SpO2< 94%, systolic reduction >20%,
- SpO2 < 88%, systolic reduction >40%, LOC
- Cardiovascular collapse requiring CPR
List risk factors for development of BCIS
Patient Factors
* Significant cardiorespiratory diseases
* Increasing age
* Osteoporosis
* Male
* ASA 3-4
* Diuretic treatment
Surgical Factors
* Intratrochanteric fracture
* Pathological fracture
* Long stem arthroplasty
Describe the pathophysiological theory for bone cement implantation syndrome
Theories:
1. Monomer theory: cement monomers in the bloodstream leading to histamine release, complement activation and vasodilatation
2. Embolus theory: medullar fat, air and monomer are released into circulation and create emboli
The pathology:
* Increased pulmonary vascular resistance
* VQ mismatch
* Dilatation of right ventricle
* Shifting of interventricular septum reduces LV compliance and CO
* Resulting in hypoxia and hypotension
Give the management for bone cement implantation syndrome
- 100% high flow FiO2
- Volume resuscitation
- Consider drugs to achieve positive inotropy e.g. norad, dobutamine
- Pulmonary vasodilators
- Vasopressors
- Invasive monitoring
- Secure airway
List techniques to reduce risk of bone cement implantation syndrome
- Wash and dry femoral canal before cement
- Avoid cement where possible
- Depressurise intramedullaary canal
- Use bone vacuum cement technique, and apply in retrograde fashion
- Retrograde cement insertion
- Low-viscosity cement
How are thyroid hormones synthesised
- Iodide uptake (into thyroid follicular cells->process stimulated by TSH)
- Iodine oxidation (to I2 by hydrogen peroxide)
- I2 reaction with tyrosine (makes monoiodotyrosine or di-iodotyrosine)
- Oxidative coupling (DIT and MIT coupling to produce T3 and T4->process stimulated by TSH)
What are the symptoms of hyperthyroidism
- Heat intolerance/sweating
- Anxiety/agitation/restlessness
- Weight loss, increased appetite
- Tachycardia/palpitations/AF
- Diarrhoea
- Fine temor
- Palmar erythema
- Proximal myopathy
- Hair loss to outer third of eyebrow
- Oligomennohrrhoea
- High outout cardiac failure
What are the causes of hyperthyroidism
- Grave’s disease
- Mutinodular thryoid
- Thyroiditis
- Toxic thryoid adenoma
- Pituitary adenoma causing TSH hypersecretion
How is hyperthyroidism diagnosed
Primary: low TSH, high T4
Secondary: high TSH, high T4
What is the treatment for hyperthyroidism
Medical
* Propythiouracil
* Carbimazole
* Radioiodine
Surgical
* Thyroidectomy
* Pituitary surgery
What are the complications of thyroidectomy
- Haemorrhage causing airway obstruction
- Tracheomalacia - prolonged pressure on tracheal by goitre
- Recurrent laryngeal nerve palsy
- Laryngeal oedema
- Hypocalcaemia (can cause laryngospasm)
List causes of chronic anaemia
- Iron deficiency
- B12 deficiency
- Folate deficiency
- Alcohol excess
- Hypothyroidism
- Anaemia of chronic disease
- Haemolytic anaemia
- Chronic bleeding
- Thalassaemia
- Sickle cell disease
List the features of severe anaemia
- Tiredness
- Palpitations/tachycardia
- Dizziness
- Dyspnoea
- Pallor
- Flow murmurs
- Signs of high output heart failure e.g. ankle swelling
How would you manage anaemia perioperatively
CPOC published guidance Sept 2022:
- Early Hb if anticipated >500ml blood loss
- If new anaemia identified, review
- Hx including NSAIDs, anticoag
- Ix including serum ferritin, transferrin sats, CRP, renal function, folate, B12, reticulocytes
- TSH, liver function, and coeliac if felt relevant - Treat cause
- If IDA, start oral iron, recheck in 4 weeks and continue until surgery if responding. If no response or oral iron not tolerated, IV iron. Oral iron can reduce absorption of levothyroxine, tertracycline and interact with Parkinson’s meds.
- If functional iron deficiency (raised CRP), as above, consider IV iron + EPO
- If B12/folate deficiency, replace with i.m injection
- If required - clinical review +/- haem referral
If anaemia identified but minor surgery/blood loss<500mls, proceed with surgery whilst ix and treatment continues
How would you reduce the risk of transfusion perioperatively in an anaemic patient?
- Cell salvage
- Tranexamic acid if indicated (CI in recent stroke)
- Surgical technique/senior operating surgeon
- Topical haemostatic agents e.g. microfibrillar collagen
- Minimuse use of surgical drains
- Neuraxial blockade
- Avoid hypothermia, acidosis, hypocalcaemia
- POC coag testing
- Judicious approach to post-operative blood sampling
- Accept restrictive transfusion trigger (70g/L, or 80g/L in cardiac disease)
Give the specific risks of blood transfusion in cancer surgery
- Increased risk of recurrence
- Lower survival rate
- Increased surgical site infection
- Increased risk of post-operative pulmonary complications
General risks:
- Incompatibility
- Infection
- Immunomodulation
- Antibody generation, so difficulty cross matching for future transfusions
- Transfusion reactions e.g. TRALI, TACO, febrile reaction
Define anaemia
Hb<130g/L in men
Hb<120g/L in non-pregnant women (WHO) or <130g/L in Anaesthesia 2017 consensus
What are the risks of perioperative anaemia
Poorer wound healing
Slower mobilisation, increased risk of thromboembolic events
Increased length of hospital stay
More likely to be transfused and risks associated
Increased risk of cardiac events
Increased risk of respiratory, urinary and wound infections
Elective surgery routine pre-op tests
- Pregnancy test if childbearing age and female sex
- HbA1c within last 3 months if diabetic
Minor surgery
* Nothing for ASA1-2
* ASA 3-4: consider renal function if at risk of AKI, consider ECG if none in 12 months
Intermediate surgery
* ASA 2: consider renal function if risk of AKI, consider ECG if cardiac disease, renal disease or diabetes
* ASA 3-4: consider FBC if cardiac disease/renal disease and symptoms not recently investigated. Consider coag if liver disease, anticoags which could be modified, surgical reason. Do renal function and ECG. Consider lung function and ABGs
Major surgery
* Everyone gets FBC
* ASA 1, consider renal function. ASA2-4: renal function tests
* ASA1, consider ECG if >65yrs and none in last year. ASA2-4: ECG
* ASA 3-4: consider coag in chronic liver disease, if taking anticoag that could be modified or if surgery warrants
Alphabet sieve: considerations for each anaesthetic management question
Airway
Breathing
Circulation
Disability
Endocrine
F-Pharmacology
GI
Haem
Infection/immunology
Joints (MSK)
Kidneys
Liver
Metabolic
Nutrition
Obstetric
Psychological
Which elements are in the Child-Pugh scoring system?
- Ascites
- Bilirubin
- Clotting (PT)
- (da) Albumin
- Encephalopathy
A: < 5% mortality from abdo surgery, 100% survival at 1 yr
B: 25% mortality from abdo surgery, 80% survival at 1 yr
C: 50% mortality from abdo surgery, 45% survival at 1 yr
What respiratory issues co-occur which chronic kidney disease that should be considered perioperatively?
- Fluid status: overload can result in pulmonary oedema and effusion
- Peritoneal dialysis: need to drain fluid as it will splint the diaphragm
- If on immunosuppression for transplant: assess for sx pneumonia
What cardiovascular issues co-occur with chronic kidney disease that should be considered perioperatively?
- HTN
- Increased risk IHD
- Calcified heart valves
- Arryhtmias from electrolyte disturbance and myocardial fibrosis
- A-V fistula
What endocrine issues co-occur with chronic kidney disease that should be considered perioperatively?
- Diabetes
- Glucocorticoid supplementation e.g. for transplant
- Secondary hyperparathyroidism
What pharmacokinetic issues should be considered in chronic kidney disease?
- Gastroparesis, slower absorption of oral drugs
- Hypoalbuminaemia increases free active drug
- Acidic environment increases active acidic drug availability
- Increased alpha-1-glycoprotein increases binding of basic drugs
- Hydrophillic drugs show increased Vd due to increased extracellular water, so serum concentation may decrease
- Reduced excretoin of renally excreted drugs and their metabolites
Which factors should be considered when planning perioperative fluid requirements in CKD
- Dry weight
- Current weight
- Dialysis mode and timing
- Ability to produce urine
- Likely blood and fluid losses intraoperatively
- Periods of restricted oral intake pre- and post-operatively
What issues should be considered when planning postoperative analgesia in CKD
- Contraindication to NSAIDs due to direct nephrotoxic effect, reduced renal blood flow, reduction in potassium excretion
- Reduced rate of renal excretion of active metabolites of morphine and dihydrocodeine, risks sedation and respiratory depression
- Hypotension from neuraxial techniques risks further renal hypoperfusion and cannot be treated with liberal fluid use
List preoperative approaches that may reduce the risk of intraoperative blood transfusion
- Optimise Hb according to haematinics giving iron replacement if required
- Review antiplatelet and anticoagulant medications and hold if appropriate
List the aspects of bedside check of a blood unit prior to transfusion
- Patient identity matched to that on blood label through core identifiers (full name, dob, ID number)
- Compatibility label has same 14-digit number as sticker on blood bag
- Expiry date and time
- Visual check for leak, discoloration, clots or clumps
Give five signs of acute transusion reaction intraoperatively
- Wheeze
- Hypotension
- Angioedema
- Rash
- Fever
WHARF
Give perioperative measures that should be considered if a patient refuses blood transfusion
- Discussion about acceptability of each blood component, risks of refusing blood, advanced decision paperwork completed
- Discussion of cell salvage
- Location of surgery discussed e.g. if day centre does not have cell salvage
- Erythropoetin use and haematinic optimisation
- Use paediatric blood sampling bottles
- Consider controlled hypotension to minimise bleeding
- Consider use of tranexamic acid and desmopressin in event of bleeding
- Announce transfusion preferences alongside WHO checklist
What are the benefits of ERAS?
- Reduced physiological stress
- Reduced length of hospital stay
- Reduced rate of complications
- Improved patient experience
What are the preoperative elements of ERAS in the weeks preceeding surgery
- Pre-operative education with input from physio, OT, nurse specialists, pain team and dieticians
- Smoking cessation at least 4 weeks prior
- Alochol cessation if any misuse
- Identify, investigate and treat anaemia
- Optimise diabetic control
- Optimise meds for chronic diseases e.g. hypertension
- Optimise pre-operative pain management
- MRSA and MSSA screening and treatment
- Perioperative medication management given
What are the preoperative elements of ERAS in the 24hrs preceeding surgery
- Clear fluids until two hours pre-operatively, solids until six hours preoperatively
- Consider using high-energy drinks preoperatively
- Staggered admission on day of surgery to minimise fasting and anxiety
- Patient pre-warming
- Antimicrobial body wash use preoperatively
What are the intraoperative elements of ERAS
- Single shot spinal anaesthetic with light sedation
- Avoid intrathecal opoids to minimise need for urinary catheter
- GA with fast acting, rapid offset agents if neuraxial technques contraindicated
- Multimodeal, opioid-sparing analgesia
- Ketamine at induction for patients with chronic pain issues
- Anti-emetics intraoperatively
- Antiobiotic prophylaxis 30 minutes prior to skin incision
- Maintain normothermia
What are the early post-operative pain elements of ERAS
- Assessment of pain at rest and on movement
- Regular oral paracetamol
- Regular ibuprofen if eGFR>60 and not on aspirin, no other contraindications
- Oral opioids for max 48hrs
- Use of music for anxiolysis and improvement of patient satisfaction
List joints affected by rheumatoid arthritis and why their involvement affects anaesthesia
- Temporormadibular joint swelling and degeneration: restricted mouth opening, may require fibreoptic intubation
- Atlantoaxial subluxation: excessive movement of neck during intubation may cause cord compression
- Cervical ankylosis: limits neck extension
- Costovertebral ankylosis: restrictive lung defect
- Interphalangeal and metacarpal involvement: inability to manage PCA
Give respiratory complications of rheumatoid arthritis
- Fibrosing alveolitis causing restrictive lung defect
- Pleurisy with effusion
- Pulmonary nodules
- Costochondral disease causing reduced chest wall compliance
Give cardiovascular complications of rheumatoid arthritis
- Inflammatory pericarditis, pericardial effusion
- Rheumatoid nodules in cardiac tissue
- Accelerated arthrerosclerosis and coronary artery disease
Give three neurological complications of rheumatoid arthritis
- Peripheral nerve entrapment (common peroneal, ulnar, median), nerve root compression esp. cervical
- Mononeuritis multiplex
- Glove and stocking peripheral neuropathy
- Autonomic dysfunction
Give contributing causes of anaemia in rheumatoid arthritis
- Annaemia of chronic disease
- Iron deficiency due to chronic GI lossess secondary to steroids and NSAIDs
- Bone marrow depression due to disease modifying drugs e.g. methotrexate
List hepatic complications of rheumatoid arthritis
- Steatosis
- Fibrosis
- Intrahepatic small vessel arteritis
- Amyloidosis
Give three common causes of chronic liver disease in adults
- Alcoholic liver disease
- Non-alcoholic liver disease e.g. obesity related
- Autoimmune e.g. primary biliary cholangitis
- Viral e.g. hep B and C
Give two risk classification scoring systems that can be used to help predict perioperative risk in patients with chronic liver disease
- Child Pugh
- Model for End-Stage Liver Disease
Give five pharmcokinetic issues that should be considered in perioperative care of a patient with severe chronic liver disease
- Increased bioavailability of oral medications due to portosystemic shunting and reduced first pass metabolism
- Reduced plasma proteins - increased free fraction of highly protein bound drugs, greater activity of thiopentone and propofol
- Increased extracellular water so greater Vd and reduction in concentration of hydrophillic drugs e.g neuromuscular blockers
- Impaired metabolism and prolonged action e.g. of opioids and neuromuscular blockers
- Reduced manufacture of plasma cholinesterases, prolonged half life of suxamethonium, remifentanil
- Reduced rate of excretion of renally excreted drugs due to hepatorenal syndrome
Explain three respiratory issues associated with chronic liver disease
- Risk of pleural effusions: reduced FRC, impaired gas exchange
- Ascites with diaphragmatic splinting: atelectasis, V/Q mismatch, reduced FRC
- Hepatopulmonary syndrome: failure to clear vasodilatory mediators causes pulmonary vasodilation, V/Q mismatch and hypoxia which cannot be corrected with oxygen
Explain cardiovascular issues associated with chronic liver disease
- Chronic inflammation results in vasodilation, sodium and water retention and a hyperdynamic state: hypovolaemia poorly tolerated, but excessive fluid administration risks pulmonary oedema and hepatic congestion
- Porto-pulmonary hypertension and right ventricular dysfunction: intraoperative hypoxia, hypercapnia, PPV may lead to right heart failure
- Cirrhotic cardiomyopathy: perioperative stress may result in decompensation perioperatively
- Coagulopathy and increased bleeding risk means difficult balance between thromboembolism and bleeding, risk of PE and DVT
List four perioperative precipitants of hepatic encephalopathy
- Sedative drugs
- Infection
- Hypoglycaemia
- Hypotension
- Hypoxia
- Electrolyte disturbance
List the physiological adaptations that offset effects of anaemia
- Increased oxygen extraction by tissues (brain and heart already have high extraction ratios so unable to compensate further)
- Right shift of oxygen dissociation curve due to increased 2,3-DPG
- Increased cardiac output
- Redistribution of cardiac output to areas of high demand such as brain and heart
Which perioperative events may worsen the effects of anaemia?
- Hypothermia causing left shift of oxygen dissociation curve
- Increased oxygen requirement due to stress response, pain, fever
- Reduced cardiac output due to anaesthetic agents
- Blood loss due to surgery
- Reduced erythropoiesis due to inflammatory response
Which blood test findings support a diagnosis of iron deficiency anaemia from a patient with microcytic hypochromic anaemia?
- Low ferritin
- Low transferrin saturations
- High total iron binding capacity
- High transferrin
Normal/high ferritin suggests functional iron deficiency (problems transporting iron for erythropoeisis)
Which blood test findings suggest haemolytic anaemia
- High reticulocytes
- Elevated LDH
- High serum iron
- High free plasma haemoglobin
- Low plasma haptoglobin
Give the elements of STOP-BANG assessment
- Snoring
- Tired in day
- Observed cessation in breathing
- Pressure - HTN treated or untreated
- BMI > 35 kg/m2
- Age > 50 yrs
- Neck circumference > 40cm
- Gender - male
How is STOP-BANG used to quantify risk of OSA
- < 2 extremely unlikely to have sleep apnoea
- 3-4 intermediate risk of OSA
- 5-8 high risk of OSA
What are the specific comorbidities associated with OSA
- Obesity
- Congenital craniofacial abnormalities e.g. Down’s, Treacher COllins
- Neuromuscular disorders e.g. myotonic dystrophy
- ENT disorders e.g. adenotonsillar hypertrophy
- Endocrine disorders e.g. hypothyroidism/enlarged goitre
What health conditions develop as a consequence of OSA
- HTN
- Arrythmias
- Diabetes T2
- Depression
Other cardiac: IHD, pulmonary hypertension, CCF
Which lifestyle issues should be addressed in a patient with recent diagnosis of OSA
- Weight loss
- Smoking cessation
- Reduce alcohol intake
- Sleep hygeine
How is OSA managed intraoperatively
- Anticipate and plan for difficult airway
- Avoid GA if feasible, use neuraxial, regional or local
- Use short acting agents e.g. propofol and remifentanil
- Full reversal of neuromuscular block with neuromuscular monitoring
- Use multimodal analgesia, avoid need for long-acting opioid
List four categories of cardiac implantable devices with an indication for each
- Permenant pacemaker: symptomatic bradycardia with AV block
- Biventricular pacemarker: heart failure with LVEF < 35% and widened QRS
- Implantable cardiac defibrillator: Secondary prevention for survivors of cardiac arrest
- Implantable loop recorder: investigate symptoms of cardiac arrythmia not picked up on ECG or holter monitoring
If a CIED is reprogrammed preoperative, what might they do?
- Response mode changed to synchonous pacing if significant pacemaker dependency
- Pause advanced functions e.g. rate response to minute ventilation, sleep/rest mode
- Switch off defibrillator function to elimiate risk of firing in response to electromagnetic interference
Why might a pacemaker fail to manage arrythmia if diathermy is used?
Pacemaker interprets diathermy current as cardiac electrical current and fails to provide appropriate rate response
How can you maximise the safety of diathermy in a patient with a pacemaker?
- Put PPM in asynchronous mode
- Use bipolar diathermy
- Apply diathermy plate away from pacemaker
- Short bursts of diathermy
- Visual assessment of impact of diathermy on ECG monitoring confirmed with pulse palpation or invasive blood pressure monitoring, if electrical capture in doubt
List non-pharmacological steps if a paced patient develops severe intraoperative bradycardia with circulatory compromise and no pacemaker response.
- Correct abnormalities in pO2, pCO2, acid-base and electrolytes
- Transcutaneous pacing
List pharmacological steps if a paced patient develops severe intraoperative bradycardia with circulatory compromise and no pacemaker response.
- Atropine 500mcg repeated to max 3mg
- Glycopyrrolate 200mcg
- Isoprenaline 5mcg/min infusion
- Adrenaline 2-10mcg/min infusion
- If betablocker or CCB overdose, consider aminophylline, dopamine and glucagon
List post-operative pumonary complications that may occur following non-cardiothoracic surgery
- Atelectasis
- Aspiration pneumonitis
- Pneumonia
- Bronchospasm
List patient related risk factors for post-operative pulmonary complications following non-cardiothoracic surgery
- Age >60 years
- Frailty
- Smoking
- Alcohol excess
- BMI >40kg/m2
List surgical risk factors for post-operative pulmonary complications following non-cardiothoracic surgery
- Emergency surgery
- Prolonged surgery
- Abdominal, ENT, major vascular, neurosurgery
Which aspects of GA may contribute to post-operative pulmonary complications following non-cardiothoracic surgery
- Residual neuromuscular block reduces ventilatory efficiency and impairs cough and swallow
- Absorption atelectasis following prolonged periods of 100% oxygen
- Failure to manage pain may cause reduced mobilisation, failure to cough and deep breathe
- Anaesthetic agents and opioids impair response to hypoxia and hypercapnnia
Which preoperative strategies may be considered to reduce the risk of post-operative pulmonary complications in the weeks leading up to non-cardiothoracic surgery?
- Optimise existing cardiorespiratory disease
- Early smoking cessation
- Prehabilitation exercise programmes
Which intraoperative anaesthetic strategies may be considered to reduce the risk of post-operative pulmonary complications following non-cardiothoracic surgery?
- Lung protective ventilation
- Short acting neuromuscular blocking agents and quantitative monitoring
- Goal direced fluid therapy
Which post-operative stategies may be considered to reduce the risk of post-operative pulmonary complications following non-cardiothoracic surgery
- Early mobilisation
- Adequate analgesia
- Lung expansion techniques, respiratory physiotherapy
What are the commonest causes of ESRF in the UK?
- Diabetes
- Glomerulonephritis
- Polycystic kidney disease
- Hypertension
What respiratory complications of ESRF are important to anaesthetists
- Pulmonary oedema from fluid overload
- Pleural effusion
- Fibrinous pleuritis
What are the causes of anaemia in ESRF
- Reduced erythropoetin synthesis
- Anaemia of chronic disease
- Iron deficiency due to altered apetite, absorption, iatrogenic sampling loss
List the acute physiological or metabolic disturbances that may be seen in a patient after haemodialsysis
- Tachycardia, hypotension (intravascular fluid depletion)
- Electrolyte changes (hypokalaemia)
- Dialysis disequilibrium syndrome (cerebral oedema with assoc. symptoms)
- Hypoglycaemia
What should you consider when providing GA for a patient on haemodialysis?
- Protection of fistula
- Protection of veins/arteries for future fistula formation
- If heparin has been given, does it require reversal for surgery
- Haemodynamic status
- How haemodialysis will be delivered post-operatively if inpatient stay required
- Appropriate drugs for use in ESRF e.g. avoid opiates that accumulate
What is prehabilitation?
Multifaceted approach to improvefunctional capacity prior to a major stressor such as surgery
What are the benefits of a prehabilitation programme?
- Reduced length of hospital stay
- Less post-operative pain
- Fewer post-operative complications
What issues are addressed as part of medical optimisation in a prehabilitation programme?
- Smoking cessation
- Alcohol intake reduction
- Weight optimisation
- Anaemia management
- Blood glucose control
- Pharmacological optimisation of chronic diseases
Give three ways a prehab programme can improve cardiorespiratory physiology
- Increased stroke volume
- Increased skeletal and respiratory muscle mitochondrial numbers, increases VO2 max
- Increased blood flow to lungs for gas exchange
Give benefits of carbohydrate preloading
- Reduces insulin resistance
- Promotes anabolism and reduces protein catabolism
Give possible benefits of nutritional optimisation preoperatively
- Improved immune function
- Improved wound healong
- Improved functional recovery
List psychologically supportive interventions that may be used in prehabilitation
- Relaxation techniques
- Support groups with similar patients
List underlying causes of aortic stenosis
- Senile calcification
- Biscuspid valve
Give values for severe aortic stenosis
- Peak aortic flow velocity
- Mean transaortic pressure gradient
- Valve area
- Peak aortic flow velocity >4m/s
- Mean transaortic pressure gradient >40mmHg
- Valve area<1cm2
List cardiac investigations used to assess severity of aortic stenosis
- Transthoracic echocardiogram
- Left heart catheter invasive haemodynamic measurements
- Low-dose dobutamine stress testing
- Cardiac MRI
What are the classical presenting features of aortic stenosis
- Angina
- Dyspnoea
- Syncope
Describe the changes that occur to the left ventricle with worsening aortic stenosis, initially compensating for its effect and latterly resulting in decompensation and display of the presenting features of angina, dyspnoea, syncope, sudden death
- Increased left ventricular systolic pressure results in compensatory left ventricular hypertrophy
- Left ventricular hypertrophy increases oxygen demand but decreases oxygen supply
- The bulkier ventricle relaxes less effectively in diastole leading to diastolic dysfunction, pulmonary congestion and shortness of breath
- Progression of diastolic dysfunction and ventricular hypertrophy lead to subendocardial ischaemia and angina
- Ejection fraction deteriorates further due to progressive outflow restriction, reduced end diastolic volume, and imbalance between left ventricular oxygen demand and supply leading to syncope and sudden death
What are the haemodynamic goals during surgery for a patient with severe aortic stenosis
- Avoid arrythmias
- Avoid tachycardia
- Maintain preload
- Maintain afterload
- Maintain contractility
What are the clinical features of myasthenia gravis
- Occular weaknes
- Generalised muscle weakness more marked promixmally
- Respiratory and bulbar weakness
- Fatiguability
What is the most common cause of muscle weakness in myasthenia gravis
- B-cell autoantibody production against acetylcholine receptors
List comorbidites that patients with myasthenia gravis are more at risk of developing
- Thymoma
- Autoimmune thyroid disease
- SLE
List possible triggers of myasthenic crisis of relevance to anaesthesia
- Infection
- Surgery
- Residual neruomuscular block
- Pain
- Hypothermia/hyperthermia
What are the management strategies to treat myasthenia gravis
- Acetylcholinesterase inhibitors e.g. pyridostigmine (with antimuscarinic to reduce adverse effects)
- Long term immunosuppression e.g. steroids
- Acute immunomodulation e.g. immunoglobulin
- Thymectomy if thymoma
What are the elements of management of neuromuscular blockade for a patient with myasthenia gravis
- Use 1/10th of the usual dose required and titrate incrementally if required
- Use neuromuscular monitoring, ideally quantitative
- Reverse neuromuscular block with sugammadex
- Avoid neostigmine which may trigger cholinergic crisis
What is the altered response to suxamethonium in patients with myasthenia gravis
- Resistance to effect (dose should be increased by 2.5 times)
- Prolonged phase II block
Which drugs may be used in the management of cholinergic crisus?
- Atropine
- Glycopyrrolate
What classical motor symptoms are used in the clinical diagnosis of Parkinson’s disease
- Tremor
- Bradykinesia
- Muscular rigidity
List airway and respiratory issues for patients with Parkinson’s disease and their perioperative consequences
- Upper airway dysfunction, reduced ability to clear secretions - aspiration
- Fixed flexion deformity of cervical spine may lead to intubation difficulties
- Restrictive pulmonary defect fue to rigitidy affecting gas exchange
- Respiratory muscle dyskinesis and bradykinesia increases risk of post-operative respiratory failure
Which drug classess are used in the routine management of Parkinson’s disease
- Dopamine precursors which convert to dopamine once past the blood brain barrier e.g. levodopa
- Peripherally acting dopamine decarboxylase inhibitors to reduce non-CNS effects of dopamine e.g. carbidopa
- Dopamine agonists mimic effect of dopamine in CNS e.g. pramipexole
- Monoamine oxidase B inhibitors reduce breakdown of dopamine e.g. seleginine
- Catechol-O-methyl transferase iinhibitors reduce breakdown of dopamine e.g. entacapone
Give examples of Parkinson’s medications that can be given when administration via the enteral route is not feasible
- Rotigotine - transdermal patch
- Apomorphine - subcut infusion
What are the complications of interruptions to administration of anti-Parkinson’s therapy
- “Off period”: increased rigity, tremor and bradkinesia
- Antidopaminergic syndrome: muscle rigidity, fever, haemodynamic instability, agitation, delerium, coma
- Dopaminergic agonist withdrawal: anxiet, depression, nausea, sweating, pain, dizziness, dysphoria, sleep disturbance
Give two classes of antiemetic that should be avoided for Parkinson’s due to antidopaminergic activity
- Phenyothiazines e.g. prochlorperazine
- Benzamide derivatives e.g. metoclopramide
What are the considerations involved in deciding the tiing of elective surgery for a patient receiving DAPT for a coronary drug eluting stent
- Risk of delay of surgery
- Risk of bleeding
- Risk of stent thrombosis
- Implication of antiplatelets on mode of anaesthesia
What is the minimum time period of DAPT following placement of a coronary drug eluting stent before surgery can be undertaking on aspirin alone
1 month
What is the strategy for perioperative management of a patient who urgently requires surgery and should discontinue DAPT
- Bridging with intavenous antiplatelet e.g. epitfibatide or tirofaban (glyIIb/IIIa inhibitors) or cangrelor P2Y12ADP receptor inhibitor
What is the recommended duration of DAPT in a patient who has had coronary drug eluting stent for ACS
12 months
What patient factors increase the risk of bleeding during DAPT
- Low Hb
- Leucocytosis
- Increasing age
- Reduced creatinine clearance
- Previous episode of spontaneous bleeding
What patient factors increase risk of stent thrombosis with coronary drug eluting stent
- Smoking
- Diabetes
- Previous PCI
- Previous MI
List three types of surgery where risk of continuing aspirin may outweight benefit to patient
- Spinal surgery
- Intracranial surgery
- Intraoccular surgery
List antiplatelet agents used in the management of patients with coronary drug eluting stents and give their mechanisms of action
- Aspirin: inihbits COX reducing production of thromboxane A2 and so reduced platelet activation and aggregation
- Clopidogrel: P2Y12 receptor inhibitor prevents ADP binding and activation of glycoproteinIIb/IIIa receptors
- Tirofaban: glycoprotein IIb/IIIa receptor blocker prevents cross-linking of fibrinogen to glycoprotin IIb/IIIa receptors on platelets
What blood test can definitively diagnose sickle cell disease
- Haemoglobinopathy screen using electrophoresis, chromatogaphy or mass spectrometry
What is the inheriance of sickle cell anaemia
- Autosomal recessive - Ch11 mutation causes change from glutamic acid to valine in beta globin
Give major pathological consquences of sickling
- Small vessel obstruction by sickled cells-> endothelial inflammation->acute and chronic organ damage and pain
- Shorter lifespan of sickled cells-> haemolytic anaemia
What does a raised blood reticulocyte count represent
- Reticulocytes are immature red blood cells
- Raised count indicates bone marrow has increased production of new red blood cells in response to increased haemolytic loss
Give airway or respiratory complications of sickle cell anaemia
- Adenotonsillar hypertrophy - leads to OSA
- Acute chest syndrome
- Chronic restrictive lung disease from repeat acute chest syndrome
- Increased susceptibility to pneumonia
Give cardiovascular complications of sickle cell anaemia
- Pulmonary hypertension
- Ischaemic stroke
- Congestive cardiac failure
Give indications for splenectomy in sickle cell anaemia
- Acute large splenic infarction
- Hypersplenism
- Acute splenic sequestration crisis
What is the role of hydroxycarbimide in the management of sickle cell disease?
Increases production of fetal haemoglobin which interferes with polymerisation of HbS and so reduces tendency to sickle
Causes neutropenia
What are the target Hb and HbS% for a 15yr old boy with sickle cell disease undergoing splenectomy
- Hb 100g/L
- Target HbS% 30%
Give perioperative factors that increase the risk of sickling
- Dehydration
- Hypotension
- Hypoxia/hypercapnoea
- Hypothermia
- Acidosis
- Infection
Give comorbidities associated with a delayed return to consciousness after GA
- Reduced central respiratory drive e.g. obesity hypoventilation syndrome
- Chronic carbon dioxide retention e.g. from COPD
- Neuromuscular disorders e.g. myasthenia gravis
- Hepatic disease
- Renal failure
- Cardiac failure
- Prexisting neurocognitive decline e.g. dementia
Give reasons why elderly patients are at increased risk of delayed return to consciousness
- Decline in CNS function leads to increased sensitivity to sedating agents
- Proportionally increased adipose component so larged Vd of lipophillic drugs which then exert a prolonged effect
- Impairment of liver or kidney function so reduced clearance of drugs and active metabolites
Give possible reasons for delayed return of consciousness after general anaesthesia after cardiac surgery with cardiopulmonary bypass
- Hypothermia
- Stroke (haemorrhagic, embolic or ischaemic)
- Electrolyte imbalance
Give two mechanisms by which opioids may contribute to delayed return of consciousness after GA
- Direct sedation via central opioid receptors
- Respiratory depression and hypercarbia
A patient is breathing spontaneously via an endotracheal tube 60 minutes after the cessation of anaesthesia, remains on full monitoring and is haemodynamically stable but has not opened their eyes. List six steps you would consider to establish and manage the cause.
- Neurological assessment: GCS, pupils, neuromuscular function
- Check temperature
- ABG for oxygen, CO2, electrolytes, acid-base and glucose
- Review anaesthetic chart and notes for risk factors
- Consider use of reversal and antidote drugs e.g. sugammadex, naloxone
- Brain imaging e.g. CT head
What is myotonic dystrophy
An inherited disorder of chloride or sodium channels altering conductance and affecting skeletal, smooth and cardiac muscle. Results in myotonia and associated multisystem effects.
What is the mode of inheritance for myotonic dystrophy
Autosomal dominance, may demonstrate anticipation
Give respiratory complications of myotonic dystrophy
- Bulbar weakness leads to weak cough, risk of aspiration and obstructive sleep apnoea
- Respiratory muscle weakness leads to respiratory failure
- Centrally driven respiratory depression can lead to central sleep apnoea and exaggerated respiratory depressant effect of opiates
- Restrictive lung defect due to progressive spinal deformity
Give cardiac complications of myotonic dystrophy
- Conduction defects and arrhythmia
- Cardiomyopathy with left ventricular failure
- Pulmonary hypertension
- Risk of embolic stroke
Give cardiovascular response to hypercarbia
- Hypertension
- Vasodilation
- Tachycardia
- Raised pulmonary artery pressure
Give three causes of hypercarbia in an anaesthetised patient
- Hypoventilation
- Rebreathing due to faulty circuit or exhausted soda lime
- Hypermetabolic state e.g. fever, malignant hyperthermia
- Increased absorption in laparoscopic surgery
Give drugs that can precipitate myotonia in susceptible patients
- Suxamethonium
- Neostigmine
N.B. pain of propofol injection can also trigger - use lidocaine
Give three non-drug triggers of myotonia in the perioperative period
- Hypothermia
- Pain
- Electrical nerve stimulation e.g. neuromuscular monitoring
Give two stategies in the management of a myotonic crisis
- Remove triggers
- Class I antiarrythmic sodium channel blockers e.g. lidocaine, phenytoin
Factors that aid clot formation
- pH> 7.2
- Temp > 35degC
- Ionised Ca >1 mmol/L
List components of equipment used in cardiopulmonary exercise testing
- Electromagnetically braked cycle ergometer or hand crank
- Rapid gas analyser
- Pressure differential pneumotachograph
- NIBP, ECG, O2 sats monitor
Give reasons for stopping CPET before maximal effort
- Hypotension
- Arrythmia
- Claudication
- ECG changes consistent with ischaemia
- Significant oxygen desaturation
Define anaerobic threshold
- The point at which oxygen demand of the body exceeds capacity of the cardiopulmonary system to supply it
- Triggering a change to ATP generation to anaerobic metabolism
- Resulting in lactate production
- Measured in mlO2/kg/min
Give two ways in which anaerobic threshold can be determined from the results of CPET
- V-slope method: graph of VCO2 plotted against VO2. The anaerobic threshold lies at the change in gradient of the graph such that there is an increase in VCO2 for a smaller increase in VO2 to create a new steeper gradient
- The nadir of the VE/VO2 curve: ventilation now driven by anaerobic production of CO2
List core measures of exercise capacity other than anaerobic threshold that can be determined from CPET
- Peak oxygen consumption (VO2 peak in ml/kg/min)
- Peak work rate WRpeak in Watts
When might CPET using a bicycle not be practical for use as a preoperative assessment tool
- Exercise-limiting peripheral vascular disease
- Lower limb amputee
- Learning difficulties or dementia sufficient to impair ability to follow instructions
- Inability to tolerate mouthpeice or facemask e.g. due to claustrophobia
Which scoring systems can be used to help predict perioperative risk before major non-cardiac elective surgery
- ASA - American Society of Anesthesiologists
- SORT - Surgical Outcome Risk Tool
- CACI - Charlson Age Comobidity Index
- RCRI - Revised Cardiac Index
- ACS NSQIP - American College of Surgeons National Surgical Quality Improvement Programme
- POSSUM - Physiological and Operative Severity Score for the enUmeration of Mortality Morbidity
Why is CO2 used for creating pneumoperitoneum in robotic laproscopic surgery
- High blood solubility, less likely to cause significant gas embolism
- Will not support combustion when diathermy is used
What complications may occur in the process of accessing the peritoneal cavity for creation of a pneumoperitoneum
- Damage to organ or blood vessel resulting in major haemorrhage
- Insufflation of vessel causing gas embolism
- Subcutaneous emphysema
- Thoracic specific: medisatinal emphysema, pneumothorax
List airway complications associated with robotic laproscopic cystectomy
- Head down position may lead to dislodged ET tube e.g. endobronchially or extubation
- Head down position may lead to airway oedema and post-operative stridor
List respiratory complications associated with robotic laproscopic cystectomy
- Head down and gas insufflation creates restrictive ventilatory defect, requiring higher pressures to achieve same tidal volumes leading to barotrauma
- Atelectasis due to pneumoperitoneum and steep Trendelenburg
- Risk of pulmonary aspiration due to passive regurgitation of gastric contents
List surgical and anaesthetic factors that contribute to risk of development of compartment syndrome in lower limbs during robotic laparoscopic cystectomy
Surgical
* Steep Trendelenburg position with strapping
* Long duration of surgery
* Lithotomy positioning using leg supports
* Restrictive intravenous fluid strategy
* Use of antiembolism stockings or intermittend pneumatic compression devices
Anaesthetic
* Neuraxial anaesthesia may lead to hypotension, and may prevent early detection
* Use of vasoactive medication
What neurological complications are related to positioning for robotic laproscopic cystectomy
- Brachial plexus injuries related to use of shoulder bolsters of beanbags
- Common peroneal nerve injury due to pressure caused by lithotomy leg supports
- Sciatic, femoral or lateral cutaneous nerve injury due to excessive flexion during lithotomy positioning
- Cerebral oedema from steep Trendelenburg
List other possible complications of positioning for robotic laparoscopic cystectomy (not airway, resp, compartment syndrome or neuro)
- Patient sliding from table
- Pressure sores from restraint devices
- DVT
Define acute liver disease
New onset liver failure evidenced by jaundice, coagulopathy and encephalopathy in a patient without pre-existing cirrhosis
Define chronic liver disease
Progressive deterioration in hepatic function over 28 weeks or more
List four risk factors which predispose to the development of AAA
- Older age > 65 years
- Male
- Cigarette smoking
- Family history of AAA
- Hypertension
- COPD
- Other vascular disease (Cerebral, coronary, peripheral)
List three ways of clinically assessing degree of blood loss in ruptured AAA
- Haemodynamics looking for tachycardia, hypotension
- Look for prolonged capillary refill time, mottled skin
- Decrease in GCS
- ABG assess for lactic acidosis
- FBC assess for Hb (or on ABG)
- Fluid balance, look for oligoanuria
- ECG may show ischaemia
List two elements in approach to intravascular resuscitation prior to surgery in ruptured AAA
- Tolerate below normal blood pressure, guided by GCS to minimise risk of clot disruption
- Use red cells, FFP and platelets in a 1:1:1 ratio
- Minimise use of non-blood fluids
- Establish large bore intravenous access for intraoperative use
A 79-year-old patient presents with a leaking abdominal aortic aneurysm (AAA). The vascular surgery and radiology teams decide to undertake an endovascular aneurysm repair (EVAR) procedure.
List three reasons why LA would not be suitable for this patient
- Back and abdominal pain associated with leaking anuerysm may be severe and not tolerated by patient
- Patient agitation due to cerebral hypoperfusion may result in poor cooperation
- Use of resuscitative endovascular balloon occlusion of the aorta (REBOA) may cause acute lower body ischaemia with intolerable pain
- Associated chronic conditions e.g. COPD and chronic cough may make lying still for prolonged periods unfeasible
Give three reasons for the risk of cardiovascular instability at the point of induction of GA for endovascular repair of a ruptured AAA
- Loss of sympathetic tone associated with pain, which may have compensated for hypovolaemia previously
- Relaxation of abdominal muscles with NMBD reduces tamponade of retroperitoneal clot
- Initiation of positive pressure ventilation reduces venous return - effect exacerbated in hypovolaeima
- Cardiodepressant effect of anaesthetic agents
List three reasons for ongoing bleeding intraoperatively during endovascular AAA repair
- Type 1 endoleak (failure to adequately create a seal on an end of the stent to the vessel wall)
- Insidious bleeding from the groin entry sites
- Failure to control coagulopathy e.g. hypothermic patient, failure to address coagulopathy with blood products
- Endovascular arterial injury during guidewire or stent manipulation
Give two post-operative complications following EVAR
- Abdominal compartment syndrome
- Ischaemic colitis
- AKI
- Lower limb ischaemia (distal dislodgement of thrombus)
Give three local or regional anaestesia techniques for carotid endarterectomy
- Superficial cervical plexus block
- Deep cervical plexus block
- Intermediate cervical plexus block
- Combined superficial and deep cervical plexus blocks
- Local anaesthetic infiltration
List four potential advantages to regional anaesthesia for carotid endarterectomy
- Allows monitoring for change in neurology intraoperatively
- Artery is closed at patient’s normal blood pressure whch may reduce psot-operative haematoma, possibly more stable blood pressure throughout
- Lower need for shunt with its risks of bubble/particulate emboli, wall dissection, kinking or thrombosis
- Avoids airway instrumentation with associated risks including spike in blood pressure at intubation and extubation
List four specific problems associated with regional anaesthesia for carotid endarterectomy
- Cervical plexus blocks have risks of intravascular LA injection, phrenic nerve damage, epidural/subarachnoid spread of LA
- Risk of failure and need to convert to GA intraoperatively with resitricted airway access
- Surgery may be prolonged with claustrophobia from drapes - affects patient experience
- Potential for patient movement causing surgical difficulty
Give three reasons for haemodynamic instability during carotid endarterectomy
- Surgical manipulation of vagus nerve - bradycardia and hypotension
- Impaired carotid baroreceptor reflex due to damage to receptor fibres at incision or removal of plaque, results in periods hypotension
- Carotid cross-clamping results in cerebral hypoperfusion and reflex sympathetically mediated compensatory increase in arterial pressure. Reverse effect on removal of cross clamp
- Patients with significant carotid artery disease are at increased risk of adverse cardiovascular events which may result in haemodynamic instability
- Comorbidities including hypertension and use of antihypertensives which may further impair baroreceptor response
List three aspects to minimise patients perioperative stroke risk during carotid endarterectomy
- Avoid shunt where possible to avoid bubble or particulate emboli
- Meticulous surgical technique to avoid dislodgement of atheroma
- Perioperative administration of antiplatelets
- Heparin before cross clamping
- Pharmacological management of perioperative hypotension to avoid ischaemic stroke and hypertension to avoid haemorrhagic stroke
The patient has straightforward carotid endarterectomy but becomes confused and agitated 4 hours later. Give three differential diagnoses
- Stroke
- Cerebral hyperperfusion syndrome (due to impaired autoregulation)
- Myocardial infarction
- Hypoxia due to post-operative haematoma compromising the airway
A 79-year-old man with a 6 cm infra-renal abdominal aortic aneurysm is to undergo an endovascular aneurysm repair (EVAR). He is known to have chronic obstructive pulmonary disease.
Give 8 advantages of EVAR compared to open repair of aneurysm
- Open repair optimal in younger patients with fewer co-morbidities because intraoperative risks are higher but there are fewer long-term problems with the graft e.g. endoleak. This gentleman is elderly and has comorbidities which place greater importance on avoiding intraoperative risks compared to long-term graft problems
- EVAR can be performed with neuraxial techniques or LA to groin, avoiding intubation and post-operative respiratory complications in a patient with COPD
- Avoids presence of large abdominal wound, the pain of which could impair breathing post-operatively
- Reduces need for opioid analgesia post-operatively, less risk of respiratory depressant and confusion effects
- Infrarenal aneurysms tend to be the most straightforward by EVAR, so operating time should be tolerable awake
- Facilitates early ambulation to prevent deconditioning in an elderly patient
- Reduced risk of large blood loss in a patient with limited reserve to tolerate it
- In view of patient’s age, likely to have other comorbidities e.g. cardiobascular - minimally invasive technqiue carries less haemodynamic stress
List risk factors for AKI in EVAR (5 patient, 2 anaesthetic, 3 surgical)
Patient factors:
* Advanced age >70 yrs
* Pre-existing renal impairment CKD 3a or above
* Diabetes
* Hypertension
* High BMI
* Peripheral arterial disease
* ACEI
* Cardiac failure
* Liver disease
Anaesthetic factors:
* Preoperative dehydration
* Failure to maintain MAP within 20% of baseline
Surgical factors:
* Repeat use of nephrotoxic drugs required e.g. contrast, aminoglycosides
* Complex EVAR e.g. fenestrated graft carries risk of stent maldeployment and obstruction of renal arteries
* Surgical complications resulting in bleeding and hypotension
* Embolisation of atheroma into renal arteries
List four perioperative measures to minimise the risk of AKI following EVAR
- Avoid perioperative dehydration by monitoring input/output, providing fluids if requiring, minimising starvation time
- Avoid perioperative hypotension, using vasopressors if indicated by cardiac output monitoring
- Avoid nephrotoxic drugs perioperatively e.g. omission of ACEI on day of surgery, care with repeat doses of aminoglycosides, limit contrast load
- Maintain glucose in normal range in diabetic patients, consider variable rate insulin infusion
- Minimise surgical complications
A 75-year-old gentleman presents for open repair of a 6 cm abdominal aortic aneurysm.
List three possible immediate effects of aortic cross clamping
Give three approaches to mitigate the effects of aortic crossclamping
- Acute increase in afterload may precipitate myocardial ischaemia, failure or arrest
- Loss of venous capacitance of distal part of body decreases circulating volume, risks pulmonary oedema
- Impaired blood flow distal to cross clamp risks mesenteric, renal, lower limb and spinal cord ischaemia
- Cross clamp over an atheromatous plauque can lead to embolic phenomena
Mitigate:
* Deepen anaesthesia to vasodilate arterial tree proximal to clamp
* Vasodilatory infusions e.g. GTN for same purpose
* Maintain adequate gas exchange to ensure adequate edelivery of oxygen to myocardium and avoid cardio-depressant effect of hypercapnoea
* Avoid siting clamp at heavily atheromatous part of aorta
Give three causes of hypotension upon removal of aortic cross-clamp during open AAA repair
Give three approaches to mitigate hypotension on removal of cross-clamp
- Sudden decrease in afterload causes hypotension
- Reduction in perfusion pressure at aortic root (due to reduction in afterload) reduces coronary perfusion pressure and may precipitate myocardial ischaemia
- Reperfusion of lower body causes recirculation of ischaemic metabolites and inflammatory mediators which have a cardio-depressant effect
- Sequestration of circulating volume back into capacitance vessels causes relative hypovolaemia and reduced venous return
Mitigate:
* Gradual release of cross-clamp
* Adequate intravascular filling prior to cross-clamp removal
* Use of vasoconstrictors and inotropes
* Stop vasodilatory infusions
* Increase minute ventilation, aiming for normocapnoea to minimise effects of respiratory acidosis compounding inevitable metabolic acidosis
* Treat electrolyte imbalance to minimise risk of arrythmia and maintain cardiac contractility
Give two approaches for maintaining distal perfusion during cross-clamp for thoracic descending aortic anuerysm repair
- Partial left heart bypass (left atrium/pulmonary vein-bypass-aorta distal to clamp or common femoral artery)
- Gott shunt (cannula connecting aorta pre-clamp and post-clamp)
- Partial femoro-femoral bypass (femoral vein-bypass-femoral artery)
Describe the blood supply to the lumbosacral segments of the spinal cord
- Anterior spinal artery: formed from branches of the two vertebral arteries at foramen magnum, supplies anterior 2/3 of cord (spinothalamic and corticospinal tracts)
- Two posterior spinal arteries: formed from vertebral arteries or PICA, supply poster 1/3 of cord (dorsal columns)
- Segmental arterial supply - paired bracnhes perfuse the spinal cord along its length. Artery of Adamkiewicz is the biggest and forms major supply to lumbosacral spinal cord, arising between T8-L4 and originates from intercostal or lumbar artery.
How can spinal cord ischaemia be minimised in patients undergoing thoracic aortic surgery
- Spinal drain to minimise CSF pressure
- Maintain MAP with adequate volume replacement and vasopressor as required
- Lowest possible site for aortic clamping (to minimise clamping above significant segmental arteries)
- Sequential clamping of aorta with neurophysioloical monitoring to detect the dominant segmental arteries
- Minimise clamp time
Spinal cord perfusion pressure = mean arterial pressure - CSF pressure
Which cranial nerves provide sensory innervation to structures encountered during awake nasal fibreoptic intubation
Trigeminal nerve: nasal air passages
Glossopharyngeal nerve: oropharynx
Vagus nerve: larynx
List five techniques that may be employed as part of an overall strategy for airway topicalisation prior to awake nasal fibreoptic intubation
- Mucosal atomisation device
- Spray-as-you-go
- Topicalisation of nasal passages with local anaesthetic soaked pledgets
- Nebulised local anaesthetic
- Cricothyroid puncture for translaryngeal block
- Individual nerve blocks e.g. glossopharnyngeal nerve block
State the maximum dose of lidocaine that can be used for topicalisation of the airway prior to awak nasal fibreoptic intubation
- 9mg/kg lean body weight
List five predictors of difficult airway that may indicate the need for awake fibreoptic intubation
- Previous difficult airway
- Limited mouth opening
- Previous radiotherapy
- Limited neck movement
- Aberrant anatomy e.g. airway tumour, previous surgery, Ludwig’s angina
- Syndromes associated with difficult airway e.g. Pierre-Robin, Treacher Collins
- Morbid obesity/OSA
State how tracheal tube placement should be confirmed prior to commencement of anaesthesia in a patient having awake nasal fibreoptic intubation
- Visualisation of tracheal lumen
- Capnography trace consistent with tracheal intubation (7 consistent waves)
Patient refusal is a contraindication to awake fibreoptic intubation. List four other relative contraindications to awake fibreoptic intubation
- Patient not able to comply with instruction e.g. confusion, language barrier, young age
- Local anaesthetic allergy
- Severe laryngeal or subglottic stenosis through which the tube/fibreoscope may not pass
- Operator inexperience
- Threat of airway obstruction
- Airway bleeding or risk of significant airway bleeding
List four airway problems that may follow removal of endotracheal tubeafter thyroidectomy
- Sore throat/hoarse voice
- Vocal cord dysfunction
- Foreign body causing obstruction e.g. teeth, throat pack, blood clot
- External compression of airway due to surgical site swelling or bleeding
- Laryngeal oedema
- Laryngospasm
- Longer term: tracheomalacia, tracheal stenosis
List four respiratory complications that may follow removal of an endotracheal tube
- Coughing
- Atelectasis causing ventilation perfusion mismatch
- Bronchospasm
- Pulmonary aspiration
- Post-obstructive pulmonary oedema
- Mucociliary dysfunction
List to cardiovascular complications that may follow removal of an endotracheal tube
- Tachycardia and hypertension may cause reduced ejection fraction in patients with coronary artery disease
- Risk of myocardial infarction due to increased oxygen demand
- Tachycardia and hypertension secondary to catecholamine release - may cause bleeding at surgical site
Give six patient-related factors that might contribute to high risk extubation:
- Airway:
* Known difficult airway
* Airway deterioration due to trauma/oedema/bleeding
* Resitricted airway access e.g. mandibular wiring
* Obesity/OSA
* Risk of aspiration - Respiratory: asthma, smoking
- Cardiovascular: IHD, arrythmia
- Neurological: Myasthenia gravis, head injury, posterior fossa surgery
- GI: Full stomach, reflux
- MSK: Muscular dystrophy, rheumatoid arthritis
Past question asked for 4 airway and 4 general risk factors that may predict difficult extubation
DAS give generalpatient factors as: cardiovascular, respiratory, metabolic (e.g. temperature) and neuromuscular. Other: location, skilled help, monitoring, equipment
List four surgical factors that may contribute to high risk extubation
- Surgery in airway/head and neck
- Surgery requiring double lumen tube
- Prolonged duration of surgery
- Trendelenberg/prone positioning risks airway oedema
Causes of hypoxia in an ICU patient who underwent tracheostomy 18 hours earlier
5
Patient:
* Pneumothorax
* Haemothorax
* Pneumo/haemomediastinum
* Atelectasis
* Aspiration pneumonitis
Equipment:
* Tracheostomy tube blocked with blood or secretions
* Dislodged tube
* Cuff puncture or deflation
* Cuff inflated with speaking valve in situ
* Ventilator circuit blockage or disconnection
* Inappropriate ventilator settings
List three patient factors that can be optimised prior to extubation
- Adequate ventilation and preoxygenation
- Correct unstable blood pressure or rhythm
- Ensure adequate reversal of neuromuscular blockade
- Correct metabolic abnormalities e.g. temperature, glucose
List two non-patient factors that can be optimised prior to extubation
- Extubation in appropriate location
- Presence of skilled assistant
- Full AAGBI monotoring
- Availability of airway kit that was necessary at intubation
List four strategies you could employ to manage high risk extubation
- LMA exchange
- Airway exchange catheter
- Tracheostomy
- Remifentanil technique
List three possible indications for exchanging an endotracheal tube for a supraglotting airway device to aid extubation
- Surgical requirement to avoid coughing e.g. occular/neurosurgery
- Avoid catecholamine surge in patients with severe ischaemic heart disease
- Staged extubation in patients at risk of airway/respiratory adverse consequences e.g. asthma, difficult airway
List five indications for tracheostomy insertion
- Prolonged mechanical ventilation
- Airway protection
- Pulmonary hygiene in patients unable to clear secretions
- As part of a surgical procedure e.g. laryngectomy, maxillofacial flap
- Upper airway obstruction
List three indications for surgical placement rather than percutaneous insertion of tracheostomy
- Trache performed as part of operating procedure
- Morbid obesity
- Challenging anatomy e.g. short neck, concerns of aberrant vessels
- Cervical instability
List four significant complications that may be encountered at the time of tracheostomy insertion
- Loss of airway
- Haemorrhage
- Pneumothorax
- Derecruitment and hypoxia
- Aspiration
- Airway trauma e.g. tracheal cartiage fracture
Patient post-tracheostomy struggling to breathe. High flow oxygen has been placed over mouth and tracheostomy. List three steps to assess tracheostomy patency
What do you do if trache is patent?
- Remove speaking valve, cap and inner tube
- Attempt to pass suction catheter via tracheostomy
- Deflate cuff if unable to pass suction catheter
- Look, listen and feel at mouth and tracheostomy site
- Connect Mapleson C and capnography to tracheostomy
If patent: perform tracheal suction, ventilate via trache if not breathing, consider partial obstruction, continue A-E assessment
Patient post-tracheostomy struggling to breathe. High flow oxygen has been placed over mouth and tracheostomy. You have extablished tracheostomy is not patent - no bag movement of Mapleson C circuit and no capnography.
- Remove tracheostomy tube
- Look, listen and feel at mouth and tracheostomy site - if not breathing call resuscitation team. Commence CPR if no pulse/signs of life.
- Primary emergency oxygenation:
- Oral airway maneouvres whilst covering stoma e.g. bag-valve-mask +/- OPA/NPA +/- supraglottic device
- Attempt ventilation via stoma using an LMA applied to stoma
- Secondary emergency oxygenation
- Attempt oral intubation, preparing for difficult intubation with an uncut tube advanced beyond stoma
- Attempt intubation of stoma using size 6 tube, consider using fibroscope/gum boujie/airway exchange
List three types of malignancy which may require tracheobronchial stenting as part of management
- Primary lung cancer
- Secondary lung metastases e.g. from breast or colorectal cancer
- Oesophageal cancer
- Thyroid cancer
- Lymphoma
List five airway concerns affecting patients requiring tracheobronchial stenting
- Risk of airway collapse on induction of anaesthesia due to loss of intrinsic muscle tone
- Risk of obstruction in supine positioning depending on nature of obstruction
- Trauma to teeth, oropharynx or larynx associated with rigid bronchoscopy use causing bleeding, obstruction and contamination of aiway
- Risk of airway contamination due to aspiration associated with rigid bronchoscopy technique
- Risk of maldeployment or migration of stent resulting in airway obstruction
- Shared airway limits access to rescue airway in event of complications
- Risk of laryngo/bronchospasm associated with airway instrumentation
List two methods of ventilation for provision of tracheobronchial stenting other than high frequency jet ventilation
- Spontaneous ventilation with transnasal humidified rapid insufflation ventilatory exchange if flexible bronchoscopy used
- Intermittent ventilation via LMA or ETT using flexible bronchoscopy
- HFNO for apnoeic oxygenation via 22mm side port of rigid bronchoscope
- Manual low frequency jet ventilation
- Intermittent controlled ventilation via circuit attached at 22mm side port of rigid bronchoscope
List three determinants of minute ventilation when using high flow jet ventilation
- Frequency of jets
- Driving pressure
- Inspiratory time
Give the principles of high frequency jet ventilation
- 120-300 jets/minute with tidal volumes smaller than dead space works through four principles
- Laminar flow in smaller airways results in faster jets in centre of airway and more resistance peripherally, where air moves in opposite direction
- Taylor dispersion/enhanced molecular diffusion - acceleratory effect of the fast moving central jet on diffusion of oxygen down its concentration gradient, so into alveoli
- Pendelluft principle - regional differences in compliance allows gas transfer between different lung units (some expand and recoil more easily than others)
- Myocardial oscillations leads to physical movement of lung units in proximity to heart (cardiogenic mixing)
List four complications of high frequency jet ventilation
- Gas embolism
- Barotrauma
- Gas trapping + hyperinflation (effects of haemodynamics)
- Inadequate ventilation with hypoxia, hypercapnoea and respiratory acidosis
List three reasons for stridor and respiatory distress after tracheobronchial stenting
- Airway bleeding
- Stent dislodgement
- Laryngeal oedema
List two characteristic findings of asthma on lung function testing
- Reduced FEV1 and FEV1/FVC < 70%
- Reversibility of above after administration of bronchodilators
Give two possible non-pharmacological reasons for poor asthma control in this patient
- Exposure to asthma triggers e.g. smoking, pets
- Comorbidities e.g. obesity, reflux
List three steps that can help to optimise the patient’s asthma control preoperatively
- Reduce exposure to triggers e.g. smoking cessation
- Reduce effect of co-morbidities e.g. weight loss if obese, treat reflux if contributing
- Address compliance or inhaler technique issues
- Involve GP or respiratory physician in optimisation of pharmacological control
- Breathing exercise programme
During surgery in an intubated asthmatic patient, peak airway pressures rise. State four causes for this aside from bronchospasm
- Kinked breathing circuit/tube
- Mucus plug blocking tube
- Endobronchial migration of tube
- Pulmonary oedema
- Pneumothorax
List three possible triggers of intraoperative bronchospasm
- Airway irritation e.g. airway secretions, instrumentation of airway, tube at carina
- Drugs causing histamine release e.g. antibiotics, neuromuscular blocking drugs, morphine
- Vagal stimulation during surgery e.g. peritoneal stretch
- Light anaesthesia
List three intravenous drugs and their bolus doses that you could use in the management of intraoperative bronchospasm
- Salbutamol 250mcg
- Adrenaline 10-100mcg
- Magnesium 2g
- Ketamine 20mg
- Aminophylline 5mg/kg
- Hydrocortisone 200mg
List three immediate approaches to ventilation to avoid the risk of barotrauma during bronchospasm
- Increase expiratory time to allow complete exhalation
- Use pressure control
- Permissive hypercapnoea
You have anaesthetised a patient for elective knee arthroscopy using a supraglottic airway device (SAD). Thirty minutes into the procedure the patient starts to desaturate and has evidence of stomach contents in the tube of the SAD. You have declared an incident and applied 100% oxygen.
List three immediate actions you would take
- Remove supreglottic airway device
- Suction airway
- Ventilate with 100% oxygen and bag-valve mask and prepare to intubate
List two patient risk factors for aspiration under anaesthesia when using supraglottic airway device
- Hiatus hernia
- Delayed gastric emptying e.g. secondary to diabetic gastroparesis
- Raised intra-abdominal pressure e.g. obesity
List two anaesthetic risk factors for aspiration when using supraglottic airway device
- Prolonged ventilation (gastric insufflation)
- Poorly fitting supraglottic airway device and positive pressure ventilation
- Light anaesthesia
List four respiratory complications that can arise within 48 hours of aspiration
- Lobar collapse
- Pneumonia
- Chemical pneumonitis
- Acute respiratory distress syndrome
List three approaches to reduce the volume and/or acidity of gastric contents preoperatively
- Adherence to fasting guidelines
- Nasogastric insertion and stomach drinage
- Premedication with prokinetics
- Premedication with acid lowering medications e.g. antacid: sodium citrate, PPI: omeprazole, H2 receptor antagonist: ranitidine
List two physiological mechanisms that help to protect against aspiration
- Lower oesophageal sphincter tone exceeds intragastric pressure
- Acute angle at gastro-oesophageal junction and by crura of diaphragm
- Upper oesophageal sphincter tone
- Protective laryngeal reflexes
List two indications for performing point-of-care gastric ultrasound
- Uncertain fasting status e.g. cognitive dysfunction
- Known delayed gastric emptying e.g. autonomic diabetes/parkinsons, acute pain, trauma
Give the antral volumes in the fasted and non-fasted patient as estimated by point-of-care gastric USS
- Fasted patient < 1.5ml/kg
- Non-fasted patient > 1.5ml/kg
- Mutation of ryanodine receptor
- Trigger agent causes sustained release of calcium from sarcoplasmic reticulum into cytoplasm, creatining sustained muscle activity
List two anaesthetic triggers for malignant hyperthermia
- Volatile anaesthetics
- Suxamethonium
List three early clinical features of malignant hyperthermia in an anaesthetised patient that should result in instigation of MH treatment
- Unexplained, unexpected rise in heart rate
- Unexplained, unexpected rise in etCO2
- Unexplained, unexpected rise in temperature
List three key elements of intial malignant hypertension management once a suspected diagnosis has been made
- Removal of trigger (remove vaporisers, maximum gas flow, 100% oxygen, hyperventilate, apply charcoal filters, change soda lime and breathing circuit)
- Patient cooling
- Dantrolene 2.5mg/kg bolus then 1mg/kg boluses every 5 minutes until etCO2< 6kPa and core temperature < 38.5 deg C
List five later onset features of malignant hypertension which may require further treatment
- Acidosis
- Hyperkalaemia
- Arrythmias
- Myoglobinuria
- AKI
- DIC
- Compartment syndrome
Give two methods for diagnosis of malignant hypertension following recovery from a suspected episode
- DNA screening blood test (tests for genetic associations)
- Muscle biopsy with in vitro contracture test in response to trigger agents
List three patient groups who should be assessed for risk of malignant hyperthermia prior to elective anaesthesia
- Blood relatives of patients with known/suspected MH
- Patients with personal history of an episode which may have been due to MH
- Patients with clinical myopathy and genetic aetiology implicated in MH susceptibility
- Patients with genetic variant in a gene implicated in MH susceptibility
- Patients with history of rhabdomyolysis of unknown cause
Give three diagnoses consistent with these blood tests
- Grave’s disease
- Toxic multinodular goitre
- Solitary hypersecreting adenoma
Give categories of Le Fort fractures
1: maxilla fractured from rest of face (transverse)
2: maxilla and nasal complex fractured from rest of face (oblique fractures)
3: whole mid-face dissociates from skull base and facial bones
How can you estimate percentage body surface area of burns?
Lund-Browder chart
TEG values, meaning and treatment
Give the location and pressure for each phase
- CVP 0-8mmHg
- Right ventricle 15-30/0-8mmHg
- Pulmonary artery 15-30/4-12mmHg
- Pulmonary capillary 2-12mmHg
Label the diagram
- Cornea
- Tenon’s capsule
- Fovea
- Optic nerve
- Vitreous humour
- Sclera
