Short Answer Questions Mock Exam Answersfrcaheadstart.org/SAQ_Feedback_Jul16.pdf · Short Answer Questions Mock Exam Answers Dr Katie Ayyash and Dr Umakanth Kempanna

Short Answer Questions Mock Exam Answers

Dr Katie Ayyash and Dr Umakanth Kempanna

General Pointers

• Read the question properly and understand what is being asked

• Answer the question asked – NOT what you want to answer about the topic

• Bullet points

• Classify/categorise

• If question asks for something “specific” – you don’t give general or superficial answers

• Don’t write extensively for low scoring sections

• Legible and neat writing – if examiner can’t read it, you won’t get the points!!!!

Question 1

A 56-year-old man is listed for elective surgery. He received an orthotopic heart transplant 12 years before.

a) What key alterations in cardiac physiology and function must be considered when planning general anaesthesia? (10 marks)

b) What are the implications of the patient’s immunosuppressant therapy for perioperative care?

(6 marks)

c) What long-term health issues may occur in this type of patient? (4 marks)

Pass rate 27%

“It is not uncommon to have a patient presenting for surgery that has received a transplanted organ and is on immunosuppressive therapy. A similar question was asked in October 2001.”

“This question proved to be the most difficult question on the paper.”

“A majority of the candidates demonstrated poor understanding of the physiology of a transplanted heart and the side effects of immunosuppressive therapy of relevance to the anaesthetist. “

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• Denervated heart - no autonomic function 1. High resting HR 90-100bpm (loss of vagal tone on SA Node)

2. No response to laryngoscopy, surgical stimulation, hypovolaemia, light anaesthesia.

3. Temporary bradyarrhythmia post transplantation - ? need for a pacemaker

4. Loss of baroreceptor reflex - No response to carotid sinus massage or valsalva maneouvre

5. Tachycardia in response to physiological stress is blunted and late depending on circulating hormones

• Cardiac output is preload dependent

• Loss of Sensory Innervation • Silent MI, hence routine regular angiogram needed.


• Pharmacology

1. Glycopyrolate and atropine - no effect (no vagal connection), but reversal of NMB.

2. Ephedrine – No/decreased effect (indirect symp)

3. Adrenaline, Noradrenaline – Augmented Response

4. Dobutamine, Isoprenaline – Normal Response

• Peripheral surgery under regional block well tolerated

• Neuroaxial blockade may cause marked hypotension due to absent cardiac innervation, but has been successfully used in these patients.

b) What are the implications of the patient’s immunosuppressant therapy for perioperative care?(6 marks) • Normally on triple therapy azathioprine, cyclosporin, prednisolone

• General: 1. Important to maintain stable plasma levels – ensure drugs are taken

2. Preop bloods: Hematological, Renal and Elecrolyte impairment.

3. Common agents can cause a degree of nephrotoxicity, hepatotoxicity

• Malignancy – Skin, lymphoproliferative.

• NSAIDS – nephrotoxic

• Steroids: 1. supplementation to account for stress response.

2. Steroid induced osteoporosis or skin fragility necessitate careful handling and positioning of the patient

• Increased risk of infection – signs maybe masked

• Prophylactic antibiotics

• Strict asepsis

• Hypertension, Cushingoid features, Psychosis, hyperglycaemia, hyperkalemia

• Monitor for classical side effects of steroids

• Steroid induced osteoporosis or skin fragility necessitate careful handling and positioning of the patient

• Cyclosporin:

1. Nephro,

2. Neuro toxic, DM, HTN, Pancreatitis, Enhances NMBs

• Azathioprine:

1. Myelosuppression, Reduces effects of NDMRs

2. Hepatotoxic, GI side effects, Pulmonary infiltrates

• Calcium antagonists increase cyclosporine levels

b) What are the implications of the patient’s immunosuppressant therapy for perioperative care? (6 marks)

c) What long-term health issues may occur in this type of patient? (4 marks) 1. Rejection

• Acute – cellular or antibody mediated, first 3 months,

• Chronic – allograft vasculopathy, immune mediated, arrhythmias, late death.

• 40% of cardiac transplant patients develop one episode of acute rejection within the 1st year

• Features:

• Accelerated coronary artery disease

• Silent myocardial ischaemia/infarction

• Heart failure

• Arrhythmia

c) What long-term health issues may occur in this type of patient? (4 marks) 1. Difficult arterial and venous access due to repeated use

2. Impaired cough due to phrenic/recurrent laryngeal nerve palsies predisposes to sputum retention and chronic lung disease

3. Higher incidence of diabetes, pancreatitis, epilepsy and hypertension

4. Higher incidence of malignancies

References

• Anaesthesia for a Patient with a Cardiac Transplant, CEACCP 2002

Question 2

a) List the nuclei of the vagus nerve. (2 marks)

b) Describe the immediate relations of the right vagus nerve in the neck at C6 (3 marks) and thorax at T4. (3 marks)

c) List the branches of the vagus nerve. (6 marks)

d) Which clinical situations commonly produce vagal reflex bradycardia? (6 marks)

Pass Rate 44.4%

“Knowledge of anatomy proved generally very poor.”

“Candidates performed better in sections (c) and (d) which were most clinically orientated. “

“Anatomical knowledge is clearly relevant to the invasive procedures undertaken in anaesthetic practice, and possibly vital to the interpretation of images generated by ultrasound devices.”

“Candidates must understand that relevant anatomy will be tested throughout all parts of the Final FRCA examination and should not write the subject off.”

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a) List the nuclei of the vagus nerve (2 marks) Nuclei of Vagus nerve lie in the medulla

1.Dorsal nucleus of the vagus (parasympathetic)

2.Nucleus Ambiguus (motor)

3.Nucleus Tractus Solitarus (sensory)

(Sensory nucleus of the trigeminal nerve - somatic sensory fibres)

b) Describe the immediate relations of the right vagus nerve in the neck at C6 and thorax at T4.

Within the carotid sheath at C6 (3 marks)

•Anterior – Omohyoid, Right lobe of thyroid gland

•Posterior – Longus cervicis, Anterior scalene muscle, Vertebral artery

•Medial – Common carotid artery, Sympathetic chain, Recurrent laryngeal nerve

•Lateral – Internal jugular vein, Deep cervical lymph chain, Sternocleidomastoid muscle, External jugular vein

b) Describe the immediate relations of the right vagus nerve in the neck at C6 and thorax at T4.

In the thorax at T4 (3 marks)

•Anterior – Phrenic nerve, Brachiocephalic trunk, Manubrium

•Posterior – Right lung

•Medial – Trachea

•Lateral – Right brachiocephalic vein

c) List the branches of the vagus nerve (6 marks)

Jugular foramen

1.Meningeal

2.Auricular

Neck

1.Pharyngeal

2.Superior laryngeal

3.Right recurrent laryngeal

4.Superior cardiac

c) List the branches of the vagus nerve (6 marks)

Thorax

1.Inferior cardiac

2.Left recurrent laryngeal

3.Branches to pulmonary plexus

4.Branches to oesophageal plexus

Abdomen

1.Gastric

2.Hepatic

3.Intestinal

4.Branches to the coeliac plexus

d) Which clinical situations commonly produce vagal reflex bradycardia? (6 marks)

1. Eye: Traction on extra-ocular muscles (oculo-cardiac reflex)

2. Anus: Dilatation of anal canal/Instrumentation of anorectum

3. Cervix: stretching

4. Peritoneum: Pulling or stretching (laparoscopic surgery)

5. Uterus: Mobilisation or Traction

6. Larynx: Laryngoscopy/Laryngospasm

7. Ovaries, Gallbladder, Liver Hilum: Traction.

8. Regional anaesthesia

9. Haemorrhage

10. IVC compression (during pregnancy)

11. Traction of testes

12. Middle ear surgery

References

• Gray’s Anatomy

• Concise Anatomy for Anaesthesia

Question 3

You are asked to review a woman in the anaesthetic antenatal clinic. She is 30 weeks pregnant and is a Jehovah’s witness. She requires an elective caesarean section at 39 weeks due to a low lying placenta and a fibroid uterus.

a)What specific issues should be discussed with this patient based on the history outlined above? (10 marks)

b)Give the advantages and disadvantages of using intra-operative cell salvage during caesarean section? (10 marks)

Pass Rate 44.6% 22.5% of candidates received a poor fail

“This question was poorly attempted by many candidates.”

“Examiners reported that answers reflected a lack of knowledge or inaccurate reading of the question.”

“Many candidates described anaesthesia for a Jehovah’s Witness patient with placenta praevia and fibroid uterus rather than addressing pre-operative discussions as was asked.”

“Candidates omitted mention of important peri-operative risks such as haemorrhage, hysterectomy and other significant morbidity and mortality.”

“Some candidates demonstrated a worrying lack of knowledge of cell salvage and in particular the disadvantages of this technique.”

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a) What specific issues should be discussed with this patient based on the history outlined above? (10 marks)

1. Elective Caesarian Section + Low placenta + Fibroid

• Anaesthetic plan:

• General anaesthetic due to increased risk of major bleeding

• Post-op analgesia, will be more difficult to manage than for regional technique- consent for TAP blocks

• Partner will not be present in theatre for birth

• Need for invasive monitoring - arterial line, consider central line.


2. Jehova’s witness

• Is she taking any medication that will impair clotting? Can these be stopped?

• What blood products will she accept and refuse?

• Would intra-operative cell salvage with a closed loop be accepted?

• Does she have an advanced directive?

• Has she discussed the issues of increased risk of bleeding and blood products with her religious leader?

• Will need to fill in a specific Trust consent form for Jehovah’s Witness patients.

• We will respect her wishes


• Can we optimise haemoglobin pre-op? - oral or intravenous iron, erythropoietin

• Can consider pre-op embolisation of intra-uterine arteries/iliacs

• Senior clinicians from obstetrics and anaesthetics will be present during the operation.

• Further increase in risk due to limitations on blood products that Jehovah’s witness will accept

• Increased risk of emergency hysterectomy, critical care post-op, death

b) Give the advantages and disadvantages of using intra-operative cell salvage during caesarean section? (10 marks)

Advantages

1.Reduced use of allogenic blood transfusion (valuable resource) therefore reduced risk of:

1. ABO incompatibility

2. Infection

3. Haemolytic transfusion reactions

4. Anaphylaxis

2.Transfused autologous blood has normal levels of 2,3-DPG

3.Transfused autologous blood has longer intravascular lifespan than allogenic blood

4.No pre-operative preparation of patient needed

5.Only >500ml of blood needed for processing - blood loss in Caesarian section often higher than this


Disadvantages

1.Cost of set up and disposables

2.Need for trained personnel to operate equipment

3.Risk of:

1. Infection in processed blood

2. Air embolism

3. Amniotic fluid embolism (should be prevented with leukocyte depletion filter)

4. Haemolysis and free haemoglobin in transfused blood leading to nephrotoxicity

5. Micro-aggregates leading to micro-embolism

6. Cell salvage syndrome (dilution of blood in saline can produce cellular aggregates that activate clotting and increase vascular permeability)


Disadvantages

• Electrolyte imbalance

• Leukocyte activation —> lung damage

• Autologous blood transfusion does not contain platelets or clotting factors - additional blood products will be required in major haemorrhage

• Time delay from collection to transfusion due to processing

References

• Perioperative Cell Salvage, CEACCP 2010

• Management of Anaesthesia for Jehovah's Witness, AAGBI 2005

Question 4

A 45-year-old man with a history of ulcerative colitis and alcohol abuse is admitted to the intensive care unit for inotropic and ventilatory support following a laparotomy to excise toxic megacolon. His body mass index is 18kg/m2.

a) Why should this patient receive early nutritional support and what are the clinical benefits?

(6 marks)

b) What is the specific composition of a nutritional regimen for this patient? (6 marks)

c) List the advantages and disadvantages of enteral nutrition (8 marks)

Pass Rate 44.9%

“This question was answered poorly. “

“The provision of enteral and parenteral nutrition in critically ill patients is very important and a detailed knowledge of the specific components of a feeding regimen is essential. The specific components required were:

Water (ml/kg/day) Calories (kCal/kg/day) Protein, fat and carbohydrate (g/day) Na/K (mmol/kg/day) and minerals Vitamins Immunonutrition “

“Many candidates failed to be specific enough. Leaving the prescribing to the “nutrition team” or “Intensive Care dietician” are not appropriate answers.“

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a) Why should this patient receive early nutritional support and what are the clinical benefits? (3 + 3 marks)

Why Nutritional Support

1.He is underweight (< 18.5 kg/m2 as per WHO classification)

2.He has a premorbid chronic inflammatory condition

3.He likely has nutritional deficiencies due to alcohol abuse

4.Early nutritional support following surgery is beneficial

5.He is acutely unwell and therefore is in a catabolic state so will have increased nutritional requirements

a) Why should this patient receive early nutritional support and what are the clinical benefits? (3+3 marks)

Clinical Benefits

1. Maintains integrity of gut mucosal barrier

2.Improved wound healing

3.Decreased infectious complications

4.Maintains nitrogen balance

5.Avoids delayed mobilization by promoting muscle mass/bulk and therefore strength

6.Avoids delayed weaning from mechanical ventilation

b) What is the specific composition of a nutritional regimen for this patient? (6 marks)

1. Calorie 30 kcals/kg

2. Water 30 mls/kg

3. Protein 1.5 g/kg

4. Remaining calorie requirement must balance between carbohydrate and fat to avoid increase in lipogenesis and RQ

Fat = 1g/kg/day, Carbohydrate = 7g/kg/day

5. Na = 1 mmol/kg/day

6. K = 1 mmol/kg/day

7. Mg = 1 mmol/kg/day

8. Ca2+ = 0.1 mmol/kg/day

9. Po43- = 0.5 mmol/kg/day

10. Trace elements – fat and water soluble vitamins

11. Vitamin B (due to alcohol abuse)

12. Micronutrients – No evidence of benefit

c) List the advantages and disadvantages of enteral nutrition (4 + 4 marks)

Advantages

1.Maintains normal physiological digestion and absorption

2.Non-invasive and cheaper

3.Preserves normal gut flora

4.Normal gastric acidity and GI barrier function is preserved

5.Decreased metabolic complications

6.No catheter associated complications

7.Decreased bacterial translocation

8.Prevents mucosal atrophy

9.Decreased stress ulcer

c) List the advantages and disadvantages of enteral nutrition (4 + 4 marks)

Disadvantages

1.Patient requires a functioning and intact GI tract

2.Diarrhoea (40%)

3.Nausea and vomiting

4.Aspiration and pulmonary injury

5.Direct pulmonary instillation

6.Electrolyte and liver function test disturbance

References

• Parenteral Nutrition in Critical Care, CEACCP 2012

• Nutritional Support in Critical Care: An Update, CEACCP 2007

Question 5

a) What are the cerebral physiological benefits of induced hypothermia following successful resuscitation from cardiac arrest? (5 marks)

b) How can a patient be cooled in these circumstances? (4 marks)

c) What adverse effects may occur due to the use of induced hypothermia? (7 marks)

d) In what other non-surgical clinical scenarios may the use of induced hypothermia be beneficial? (4 marks)

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a) What are the cerebral physiological benefits of induced hypothermia following successful resuscitation from cardiac arrest? (5 marks)

1. Reduces cerebral metabolism by 7% for every 1°C leading to less oxygen and glucose consumption

2. Promotes cerebral vasoconstriction leading to a decrease in ICP

3. Decreased excitatory neurotransmitter mainly glutamate

4. Decreases calcium flux

5. Prevents neuronal injury leading to apoptosis

6. Decreases neurochemical motor expression

7. Improves ionic homeostatis

8. Decreases free radical formation

b) How can a patient be cooled in these circumstances? (4 marks)

• Physical: 1. Fans—may increase infection risk

2. Ice packs to the femoral area, major vessels, and armpit

3. Cold fluids via intravascular line

4. Water filled blankets or garments

5. Forced cold air

6. Bypass—specialist (cardiac) areas only

7. Cooling caps (mainly used in neonates and infants)

• Pharmacological: 1. Antipyretics, for example, paracetamol

OR can be classified as passive/active cooling


1. CVS

2. RS

3. Neuro

4. Metabolic

5. Renal

6. GI

7. Haematological


Cardiovascular

• Decreases cardiac output by 30% at 30°C

• Increases risk of angina, myocardial ischaemia and cardiac arrest

• Increased risk of ventricular arrhythmias at 30°C, VF at 28°C

• Increases SVR and PVR

• Increases catecholamine release

• ECG – prolonged PR interval, wide QRS complex, J waves

c) What adverse effects may occur due to the use of induced hypothermia?

Respiratory

•Apnoea occurs at 24°C

•Decreases O2 delivery (Left shift of the oxygen-haemoglobin dissociation curve)

•Decreases O2 demand and CO2 production

•Mild respiratory and metabolic acidosis

Neurological

•Shivering thereby increasing basal metabolic rate

•Confusion <35°C

•Unconsciousness at 30°C

•Cessation of cerebral activity <18°C


Metabolic

•Decreases metabolic rate by 6-7% by every 1°C in core temperature

•Decreases enzyme activity

•Hyperglycaemia secondary to fat mobilisation

•Electrolyte shift

Renal

•Decreases GFR by 50% at 30°C

•Diuresis due to inability to absorb sodium and water


GI

•Decreases gut motility leading to ileus

•Decreases gut translocation of bacteria

Haematological

•Increases blood viscosity and haematocrit < 30°C

•Thrombocytopenia caused by hepatic and splenic sequestration

•Impaired platelet function

•Immunosuppression

•Increases risk of DVT/PE

d) In what other non-surgical clinical scenarios may the use of induced hypothermia be beneficial? (4 marks)

1. Post cardiac arrest

2. Traumatic head injury

3. Ischaemia stroke

4. Spinal cord injury

5. Newborn hypoxic–ischaemic encephalopathy

6. Raised ICP seen in hepatic encephalopathy

7. Treatment of malignant hyperthermia and drug overdoses e.g. serotenergic syndrome

References

• Clinical Implications of Induced Hypothermia, CEACCP 2006

Question 6

a) What characteristic neurological changes occur immediately and in the first three months following transection of the spinal cord at the fourth thoracic vertebra? (5 marks)

b) What other clinical problems may develop following this type of injury? (8 marks)

c) List the advantages of a regional anaesthetic technique for cystoscopy in this patient. (4 marks)

d) Why and when may suxamethonium be contraindicated in a patient with spinal injury?

(3 marks)

Pass rate 49.4%

“The examiners commented that part (d) about the advantages of regional anaesthesia for elective lower limb surgery, was not well answered.”

“Candidates tended to give general answers such as “avoids the need for general anaesthesia” or “maintains cardiovascular stability” rather than specific advantages such as “reduces the risk of autonomic dysreflexia” or “avoids postoperative respiratory inadequacy due to general anaesthesia”.

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Immediate Changes

•Days 0-1: Spinal shock develops where there is loss of reflexes below the level of T4 resulting in flaccid areflexia. This is usually combined with hypotension of neurogenic shock


Changes in first 3 months

•Days 1-3: Gradual return of reflex activity when the reflex arcs below the level of the lesion redevelops. Loss of descending inhibitory control leads eventually to spasticity and autonomic hyperreflexia

•Days 4-28: Early hyperreflexia develops. This results as a stimulation of the autonomic nervous system which can lead to profound systemic symptoms, including hypertension, tachycardia, flushing, sweating and headaches.

•Months 1-12: Development of late hyperreflexia


1. RS

2. Hypotension

3. Autonomic Dysreflexia

4. Haematological

5. GI

6. Skin

7. Musculoskeletal

8. Temperature

9. CNS

1. RS: • Respiratory function may be compromised leading to:

1. Need for long term mechanical ventilation via a tracheostomy

2. Absent or impaired cough reflex leading to retention of secretions and increased risk of lower respiratory tract infections

2. Hypotension: • Incomplete recovery from neurogenic shock leading to postural hypotension that

can be a persistent problem

3. Autonomic Dysreflexia: • Sympathetic hyperreflexia – a life-threatening condition triggered by somatic or

visceral stimuli below the level of the injury

4. Haematological: • Risk of thromboembolic events due to immobility and thrombogenicity secondary

to trauma


5. GI: • Risk of peptic ulceration due to unopposed vagal activity thereby increasing

gastric acid secretion

• Gastroparesis and ileus development leading to nausea, vomiting and risk of aspiration and abdominal distension impairing respiration

• Constipation is often problematic as sensation of defecation is lost

• May require enteral feeding and therefore glycaemic control is essential to avoid hypo- and hyperglycaemic episodes

6. Skin: • Development of pressure sores as a result of immobility, poor perfusion of the

skin and hypoxia

7. Musculo- skeletal: • Development of contractures from spasticity. Both painful and decrease function,

compromise posture, and reduce functional capacity

• Reduced bone density and increased risk of fractures


8. Temperature: • Impaired thermoregulation

9. CNS: • Psychological disturbance – depression, anxiety, confusion


c) List the advantages of a regional anaesthetic technique for cystoscopy in this patient (4 marks)

1. Completely abolishes the risk of autonomic dysreflexia

2. Avoidance of some of the hazards of general anaesthesia in such patients

1. Aspiration: Avoidance of risk of aspiration secondary to gastroparesis

2. Airway: May have a difficult airway (Trache, Spinal Fixation)

3. RS: Avoidance of respiratory complications and post-op ventilation

4. CVS: Risk of profound hypotension due to loss of sympathetic response (lesions above T6 and unopposed parasymp)

3. CVS / RS / GI (reduced opioid) / Haematological / Reduced risk of thrombo-embolism

d) Why and when may suxamethonium be contraindicated in a patient with spinal injury? (3 marks)

1. Suxamethonium is safe to use in the first 72 hours and after 9months following the injury

2. Extra-junctional Ach receptors

3. In the intervening period there is a risk of suxamethonium-induced hyperkalaemia due to denervation hypersensitivity and therefore should be avoided

References

• Initial Management of Acute Spinal Cord Injury, CEACCP 2013

• Anaesthesia and Acute Spinal Cord Injury, CEACCP 2002

Question 7

A 71-year-old patient requires a rigid bronchoscopy for biopsy and possible laser resection of an endobronchial tumour.

a) Outline the options available to maintain anaesthesia (4 marks) and manage gas exchange. (6 marks)

b) How will use of the laser change the management of anaesthesia? (3 marks)

c) What are the possible complications of rigid bronchoscopy? (7 marks)

Pass Rate 60.8%

“This question proved discriminatory between candidates who gave a mature and thoughtful answer and those that did not understand the implications of “tubeless” ENT / thoracic surgery.”

“Weaker candidates proposed the use of laser-proof endotracheal tubes, and even double lumen endobronchial tubes and cardiac bypass to facilitate gas exchange.”

“Part (a) tended to score scored badly whilst parts (b) and (c) were better known.”

“Focus in part (c) was dominated by traumatic complications with candidates forgetting “anaesthetic” issues such as; laryngospasm and bronchospasm, pneumothorax / barotrauma / volutrauma from jet ventilation, cardiovascular disturbances, pulmonary infection, hypoxaemia, hypercarbia and awareness.”

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a) Outline the options available to maintain anaesthesia and manage gas exchange. (4 + 6 marks)

Options to maintain anaesthesia: (4 marks)

1.TIVA (Total intravenous anaesthesia)

2.Inhalation: anaesthesia via side arm of bronchoscope with patient spontaneously breathing (paediatric anaesthesia, typically for inhaled foreign body)

a) Outline the options available to maintain anaesthesia and manage gas exchange.

Management of gas exchange: (6 marks)

1.Low frequency jet ventilation (LFJV)

2.Spontaneous respiration through bronchoscope with Mapleson F circuit attached (ideally for paediatric population)

3.High frequency jet ventilation

b) How will use of the laser change the management of anaesthesia? (3 marks)

1. Warning sign on theatre door, locking theatre door and blacking out of all windows

2. Protective goggles for patient and theatre staff members

3. Minimum FiO2 should be used during procedure

4. Saline should be immediately available to deal with airway fire

5. Consideration should be given to using a laser resistant tube instead of rigid bronchoscope

6. Dexamethasone maybe required to reduce swelling post operatively

7. Requires training on use of Lasers for theatre staff

8. Nitrous oxide must not be used

c) What are the possible complications of rigid bronchoscopy? (7 marks)

1. Physical: 1. Dental damage

2. Sore throat

3. Hyper-extension of neck can cause basilar artery insufficiency

4. nerve damage to nerves of cervical spine

5. Trauma to the airway leading to swelling or bleeding

2. Physiological: 1. If LFJV or HFJV used then:

1. barotrauma

2. volutrauma

3. pneumothorax

2. Increased risk of awareness

3. Environment: • Pollution due to inhalational agents

References

• Anaesthesia for Airway Surgery, CEACCP 2006

Question 8

a) What types of infusion control devices are used in clinical settings? (3 marks)

b) What are the general (4 marks) and specific (7 marks) characteristics of pumps used for target controlled infusion (TCI) anaesthesia?

c) What precautions should be undertaken to guarantee drug delivery when administering total intravenous anaesthesia (TIVA)? (6 marks)

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a) What types of infusion control devices are used in clinical settings? (3 marks)

1. Target controlled infusion pumps e.g Alaris

2. Fluid pumps e.g. Graseby

3. Epidural infusion

4. PCA pumps

5. Syringe drivers

6. Pain busters

b) What are the general and specific characteristics of pumps used for target controlled infusion (TCI) anaesthesia?

General (4 marks)

1.Battery or mains operated

2.User interface to enter patient details

3.Display screen for information regarding protocol and infusion data

4.Alarm for power failure or low battery

5.Alarms for syringe disengagement, end of infusion, occlusion or high resistance

b) What are the general and specific characteristics of pumps used for target controlled infusion (TCI) anaesthesia?

Specific (7 marks)

1.Can set and adjust target plasma or effect-site concentration of drug

2.Software with pharmacokinetic model validated for specific drug to control infusion rate

• Models are derived from previously performed pharmacokinetic studies

• Computer continuously calculates the patient’s expected drug concentration and adjusts drug infusion rate

3.Communication between ‘control unit’ and pump hardware

• Computer-controlled motor turning screw that pushes syringe plunger

4.Specific Drugs: Propofol (Marsch / Schneider), Remifent (Minto)

5.Pumps themselves do not provide depth of anaesthesia monitoring

c) What precautions should be undertaken to guarantee drug delivery when administering total intravenous anaesthesia (TIVA)? (6 marks)

1. Dedicated intravenous line

2. Regular monitoring of cannula site checking for disconnection or tissuing – cannula should be easily visible

3. Non-return valve should be used on any intravenous fluid line (when multi-lumen IV connectors used)

4. Anti-siphon valve prevents siphonage into pump-controlled medication lines

5. Ensure all infusion devices are fit for purpose – systematic checks of all pumps

6. Ensure all staff trained in how to operate infusion pumps

7. Depth of Anaesthesia Monitoring – Clinical / Equipment – BIS, Entropy, etc.,

References

• Safe Anaesthesia Liaison Group - Guaranteeing Drug Delivery in Total Intravenous Anaesthesia

Question 9

a) What are the site of action and the intra and extracellular mechanisms of analgesic effect within the spinal cord following the administration of intrathecal (IT) opioids? (6 marks)

b) List the principal side effects of IT opioids. (7 marks)

c) What factors may increase the risk of postoperative respiratory depression following administration of IT opioids? (7 marks)

Pass rate 31.7%

“It was anticipated that candidates would find this question difficult, and this proved to be the case.”

“Intrathecal opioids are used widely in anaesthetic practice but candidates’ knowledge of their use was poor.”

“Advanced sciences are part of the intermediate curriculum so knowledge of applied pharmacology is expected.”

“Some candidates failed to read part (b) of the question and gave the side effects of intravenous opioids or intrathecal local anaesthetic in their answer.“

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Number of Candidate

a) What are the site of action and the intra and extracellular mechanisms of analgesic effect within the spinal cord following the administration of intrathecal (IT) opioids? (6 marks)

1. After injection – slow cephalad and circumferential spread.

2. G-protein: Intrathecal opioids bind to G-protein-linked pre- and postsynaptic opioid receptors

3. Site: Laminae I and II of the dorsal horn

4. Receptor activation leads to G-protein- mediated potassium channel opening (mu and delta) and calcium channel closure (kappa)

5. This results in a reduction in intracellular calcium

6. This reduces the release of excitatory transmitters (glutamate and substance P) from presynaptic C fibres, but not A-fibre terminals

7. This causes a reduction in nociceptive transmission

8. Other possible target sites: C fibres (fentanyl), increase in adenosine (morphine), post synaptic receptor sites in dorsal horn – K channel opening – indirect activation of descending inhibitory pathways.

b) List the principal side effects of IT opioids. (7 marks)

1. RS: Respiratory depression

2. GI: • Delayed gastric emptying

• Nausea and vomiting

3. Pruritus (mechanism not understood)

4. CNS: Sedation

5. Urinary retention

6. Sweating

7. Shivering

c) What factors may increase the risk of postoperative respiratory depression following administration of IT opioids? (7 marks)

1. Administration of high dose intra-thecal opioids

2. Increasing age

3. Concomitant use of long acting sedatives

4. Positive pressure ventilation

5. Co-existing respiratory depression

6. Co-administration of opioid analgesics during the first 12-24 hours after intra-thecal administration

(? Others: OSA, Obesity, Premature / very young)

References

• Intrathecal Opioids in the Management of Acute Postoperative Pain Relief, CEACCP 2008

Question 10

A one-day old term neonate has arrived at your regional paediatric intensive care unit. A congenital diaphragmatic hernia has been diagnosed. The baby is already intubated and receiving artificial ventilation.

a) What is congenital diaphragmatic herniation? (2 marks)

b) How may it present and how may it be diagnosed? (4 marks)

c) What are the anaesthetic implications, including ventilator strategy when anaesthetising these patients? (6 marks)

d) What problems may occur intra-operatively and post-operatively? (8 marks)

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a) What is congenital diaphragmatic herniation? (2 marks)

1. Diaphragm fails to close properly during fetal development. The resulting defect allows the abdominal contents such as bowel to enter the thoracic cavity.

2. It is more common on the left side via the foramen of Bochdalek

3. Lung development on the affected side is abnormal and displays hypoplasia with poorly developed airways, fewer type 2 pneumocytes and highly reactive pulmonary vasculature

b) How may it present and how may it be diagnosed?(4 marks)

• CDH can be diagnosed antenatally and postnatally

Antenatally

• Ultrasonographic features that suggest CDH include polyhydraminos, visualization of the stomach or bowel in the thorax and mediastinal shift away from the hernia

• Average gestational age at diagnosis is 24 weeks

Postnatally

• History / Presentation: •CDH often presents as respiratory distress with tachypnea and cyanosis in the neonatal period. This is due to associated pulmonary hypoplasia and pulmonary hypertension.

• Examination: • Abdomen is scaphoid and the thorax barrel-shaped.

•Breath sounds are absent on the affected side (most commonly the left side) and the heart sounds are shifted to the opposite side (most commonly the right)

•Bowel sounds on the affected side are an uncommon finding.

•Investigation: •Diagnosis is made by chest radiograph showing abdominal contents in the thoracic cavity after birth.

b) How may it present and how may it be diagnosed?(4 marks)


Anaesthetic Implications specific to CDH

1.Surgical correction of the defect is not an emergency as it will not improve ventilation.

2.At delivery bag mask ventilation should be avoided as it inflates the stomach and impairs ventilation

3.The trachea is intubated and a ‘gentle ventilation’ strategy is used. This strategy encompasses:

• Limiting inspiratory pressures to < 25cm H2O

• Low tidal volumes

• Permissive hypercapnia

• Allowing spontaneous respiration.

• This reduces barotrauma and further damage to the hypolastic lung

•High frequency oscillator/ECMO may be required



1. FiO2 adjusted to preductal arterial saturations >85%

2.A large orogastric tube is inserted to deflate the stomach

3.Neoenate is stabilised in NICU where arterial and central venous access can be gained

4.Ongoing management is focused on trying to reduce pulmonary vascular resistance (PVR) as these neonates have pulmonary hypertension.

5.Inhaled nitric oxide is a selective pulmonary vasodilator that reduces PVR

6.After 24-48hrs and a period of stabilisation with falling PVR surgery is performed



•Key anaesthetic considerations in theatre are:

• To prevent any rise in PVR by adequate oxygenation

• Avoiding acidosis

• Avoiding hypothermia

• Continue any pharmacological infusions from NICU to reduce PVR

•Inhalational agents with the exception of nitrous oxide can be used

•Often there is cardiovascular instability so opioids and muscle relaxants are the key drugs used


Intra-operatively

Specific to CDH

1.Pneumothorax particularly contralateral side if pressures exceed 40cmH2O. Can be life threatening and requires immediate decompression 2.Pulmonary hypertension impairs oxygenation and reduces cardiac output

General to Neonate 1.Hypothermia 2.Hypoglycaemia 3.Bradycardia 4.Hypovolaemia with what appears to be low blood loss


Post-operatively

Specific to CDH

3. Difficulty weaning from ventilation 4. Pulmonary hypertension can worsen oxygenation and ventilation and ECMO may be required 5. Chronic lung disease 6. Hernia recurrence 7. Nutritional problems and GORD

8. Neurodevelopmental delay

General to Neonate 5. Risk of apnoea 6. Respiratory failure

References

• Congenital Diaphragmatic Hernia in the Neonate, CEACCP 2005

Question 11

a) List the key principles of consent for anaesthesia. (12 marks)

b) Which patients may be unable to give consent (2 marks) and how is this situation approached? (6 marks)

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a) List the key principles of consent for anaesthesia.(12 marks)

1. Autonomy: Patient has the right to refuse or choose their treatment

2. Beneficence: Act in the best interest of the patient

3. Non-maleficence: “first, do no harm”

4. Justice: fairness and equality. Concerns about distribution of scarce health resources, and the decision of who gets what treatment.


• No actual ‘form’ but verbal with brief documentation of risk

• Written patient information

• Patient given time to take away information, read and understand

• Given chance to ask questions

• Informed

• Risk/ benefit explained

• No coercion- given freely

• Below 15

• Gillick competence- patient can consent for treatment but not refuse

• Child under 15 with competence can go against parents’ wishes


• Capacity

• Able to understand information, retain information long enough to weigh risk and benefit then communicate decision

• All patient assumed to have capacity unless proven otherwise

• Apparently unwise decision does not imply patient does not have capacity

• Patient can have capacity for one decision but not another

• Patients need to be given as much assistance as required to help them make decisions for themselves


• Lack capacity

• In emergency- decision in patient’s best interest

• Family can be consulted but not necessary followed (evidence of patient’s wishes but not in themselves determinative)

• Lasting power of attorney (LPA)- must register with the court of protection to be valid

• If dispute between clinician and LPA and concerns that LPA not acting in best interest return to court of protection


• Language issues

• Always aim to get interpreter- in person/ by phone

• Written information

• Advance directive/ living will

• Done when patient has capacity for use in the event that they lose capacity

• For specific condition/ treatment only

• Mental Capacity Act

• Protects patients who lack capacity

b) Which patients may be unable to give consent (2 marks) and how is this situation approached (6 marks)?

Patients unable to give consent Approach

Acute •intoxication •GA •Head injury (concussion)

• Wait for capacity to return • If emergency/ life threatening- treat

in best interest. Treatments in this situation must cause least disruption to patient

Long term conditions •Degenerative (Parkinson’s, dementia) •Mental health issues •Head injury/ permanent brain damage

• Treat in best interest • Lasting power of attorney • Independent mental capacity act

(IMCA) • Advanced directive • Court order

Children • Gillick competence in older patient • Parental consent in younger

children • If clinician feels parents not acting

in child best interest court order can be sought

References

• General Medical Coucncil

Question 12

a) What airway, respiratory and cardiovascular problems may follow the removal of a tracheal tube? (10 marks)

b) List the patient and surgical factors that may contribute to a high-risk extubation. (6 marks)

c) Outline the strategies used to prevent airway complications if a difficult extubation is anticipated in the operating theatre. (4 marks)

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Airway

1.Airway obstruction

1. Laryngospasm (most common)

2. Tongue obstructing airway

3. Laryngeal oedema, haemorrhage

4. Decrease in muscle tone

5. Trauma to airway

6. Vocal cord paralysis/dysfunction (in head & neck / thoracic surgery)

7. Airway compression (expanding haematoma)

2.Pulmonary aspiration

3.Tracheomalacia (certain surgical pathology, prolonged intubation)


Respiratory

1.Coughing

2.Central respiratory depression due to residual anaesthetic drugs, opioids

3.Early postoperative hypoxaemia –

• Range of causes - inadequate MV, airway obstruction, increased V/Q mismatch, diffusion hypoxia, post-hyperventilation hypoventilation, shivering, inhibition of hypoxic pulmonary vasoconstriction, mucociliary dysfunction, decreased cardiac output

4.Bronchospasm – smokers, COPD pts, children with URTI

5.Residual neuromuscular blockade may cause respiratory difficulties

6.Post-obstructive pulmonary oedema (respiratory distress, haemoptysis, CXR changes consistent with pulmonary oedema)


Cardiovascular

1.10-30% increase in arterial pressure and heart rate, lasting 5-15 minutes

2.Decreased ejection fraction (40-50% in patients with CAD)

3.Myocardia ischaemia in high risk patients


Patient factors : (Predictors of difficult intubation imply potential for difficult extubation)

1.Airway pathology – congenital or acquired

2.Known/previous difficult airway

3.MP 3 or 4

4.Limited neck movements/cervical spine instability (RA, Downs, OA, Ankylosing Spondylitis, surgical fixation)

5.Morbid obesity

6.OSA

7.Severe gastroesophageal reflux

8.Multiple attempts at intubation

9.Airway deterioration – trauma, bleeding, oedema

10.Severe cardiorespiratory disease


Surgical factors

1.Neck immobilisation (C-spine surgery)

2.Intermaxillary fixation

3.Presence of Halo/traction limiting access to mouth

4.Head & Neck surgery - Haematoma, oedema and distorted anatomy

5.Posterior fossa surgery

6.Drainage of deep neck and dental abscesses

7.Thyroid surgery – risk of tracheomalacia, recurrent laryngeal nerve damage


Follow DAS Extubation Guidelines

Step 1: Plan

Assess Airway and general risk factors

Step 2: Prepare

Optimisation patient and other factors

(patient – CVS, respiratory, metabolic / temperature, neuromuscular)

(other factors – Location, skilled help and assistance, monitoring, equipmen)


Step 3: Perform Extubation

Safe to remove tube – Awake extubation, Advanced Techniques (LMA, Remifentanil technique, Airway Exchange Catheter)

Not safe to remove tube – postpone extubation, Tracheostomy

Step 4: Postextubation Care

Recovery / HDU / ICU (Safe transfer, handover/communication, O2 and airway management, Observation and monitoring, analgesia, staffing, documentation)

References

• Tracheal Extubation, CEACCP 2008

• DAS Extubation guidelines

Documents

Short Answer Questions Mock Exam Answersfrcaheadstart.org/SAQ_Feedback_Jul16.pdf · Short Answer Questions Mock Exam Answers Dr Katie Ayyash and Dr Umakanth Kempanna