CR paper 6 Flashcards
Question 1. Emma, a 40-year-old woman, is listed for excision of a vestibular schwannoma (acoustic neuroma).
a) List four commonly encountered clinical features of this condition. (4 marks)
• Unilateral sensorineural hearing loss
• Unilateral tinnitus
• Balance problems/vertigo
• Cranial nerve V (trigeminal) palsy causing facial numbness/ paraesthesia, decreased corneal reflex
**NB Cranial nerve VII (facial) palsy is rare but is a complication of surgical excision. Headache is uncommon, except for large tumours.
**Acoustic neuroma is a benign tumour of the Schwann cells of the vestibular division of the eighth cranial nerve.
Patients usually present with symptoms when the tumour is relatively small.
Question 1. Emma, a 40-year-old woman, is listed for excision of a vestibular schwannoma (acoustic neuroma). a) List four commonly encountered clinical features of this condition. (4 marks)
The neurosurgeon is planning a translabyrinthine approach in the supine position as it is associated with a lower risk of damaging the seventh cranial nerve. b) List four clinical features of seventh cranial nerve palsy due to neurosurgical trauma in this case. (4 marks)
• Unilateral weakness of facial muscles
• Unilateral loss of taste/metallic taste
** Chorda tympani damage.
• Unilateral decrease in salivation
• Unilateral decrease in tear production
*Greater petrosal nerve palsy.
• Inability to close eye/ptosis
**Damage to temporal and zygomatic branches.
c) List two other positions employed for excision of posterior fossa tumours. (2 marks)
• Prone
• Lateral/park bench
• Sitting
**The sitting position offers
the best surgical operating conditions, but carries ahigh risk of venous air embolism.
Thepatient is anaesthetised, transferred onto the operative table and positioned supine with her head turned to the side. The surgery is expected to take more than 8 hours. d) List four precautions you would take when positioning the patient. (4 marks)
• Padding of elbows/supination of forearm: risk of ulnar nerve compression injury
• Padding of heels
• Careful securing of endotracheal tube, so as to not cause pressure
on lips
• Avoid straight legs: pillow under knees
• Avoid extreme head rotation: risk of brachial plexus stretch injury
• Avoid tension on urinary catheter: pressure injury to bladder neck
• Tape eyelids closed; padding of eyes
e) List three strategies employed in neuroanaesthesia to avoid the patient coughing on extubation. (3 marks
• Use of opioid to suppress cough reflex
• Spontaneous breathing deep extubation
• Exchange endotracheal tube for laryngeal mask airway
• Lignocaine (intravenous bolus or within endotracheal cuff)
**Most commonly achieved through use of a remifentanil infusion
f) The patient fails to wake following surgery. List three possible neurosurgical causes for decreased consciousness following posterior fossa surgery. (3 marks
• Haematoma: subdural/ extradural/intraparenchymal
• Direct injury to brainstem during surgery
• Hydrocephalus
**The posterior fossa is a very small space: a small volume
of blood or parenchymal oedema can compress the brainstem or obstruct
cerebrospinal flow
Question 2 Matthew, a 67-year-old man known to have chronic heart failure, is listed for an elective femoral endarterectomy. a) Aside from advancing age, list three common causes of chronic heart failure within the Western world. (3 marks)
• Hypertension
• Diabetes mellitus
• Ischaemic heart disease
• Valvular disease
• Cardiomyopathies
• Alcohol abuse
**Mechanisms of heart failure
can be subdivided into three
types:
• Myocyte death (e.g.
ischaemic heart disease,
alcohol, myocarditis)
• Myocyte dysfunction
(e.g. pregnancy,
nutritional deficiencies)
• Circulatory dysfunction
(e.g. valvular heart
disease, protracted
severe anaemia)
Physiologically, the reduction in myocardial contractility seen in heart failure reduces stroke volume and increases both left ventricular end-diastolic volume and pressure. b) State the two main re-modelling effects this has on the left ventricle. (2 marks)
• Hypertrophy
**As myocardial contractility decreases, the stroke volume (SV) decreases, which leads to an increase in left ventricular end-diastolic pressure (LVEDP).
According to the Frank–Starling mechanism, this increased LVEDP restores SV.
○ In the longer term, this left ventricular volume overload causes myocardial re-modelling – the subsequent hypertrophy and dilatation result in an increase in ventricular wall stress and oxygen demand.
c) The diagram below is of a normal left ventricular pressure–volume loop. Indicate the following: 1. Stroke volume, SV (1 mark) 2. Left ventricular end-diastolic pressure, LVEDP (1 mark) 3. End-systolic pressure–volume relationship (1 mark)
○ Compared to the normal cardiac loop, the failing left ventricular loop demonstrates
• rightward shift of end-systolic volume, due to impaired contractility
• raised LVEDP due to impaired myocardial relaxation
• a reduction in the width (i.e. reduction in SV) as a consequence of a
higher end-systolic volume
• a lower end-diastolic volume.
On the same diagram, draw a loop to represent a chronically failing left ventricle with both diastolic and systolic impairment. Ensure that you indicate any changes in LVEDP or SV.You may assume that heart rate and systemic vascular resistance are unchanged. (3 marks) d) The chronic reduction in cardiac output seen in heart failure invokes a neuroendocrine response activating which two systems? (2 marks)
Compared to the normal cardiac loop, the failing left ventricular loop demonstrates:
• rightward shift of end-systolic volume, due to impaired contractility
• raised LVEDP due to impaired myocardial relaxation a reduction in the width (i.e. reduction in SV) as a consequence of a higher end-systolic volume
• a lower end-diastolic volume.
d)
• Renin–angiotensin–aldosterone system (RAAS)
• Sympathetic nervous system (SNS)
**The reduction in cardiac output (CO) activates the RAAS, resulting in salt and water retention and an increase in circulating volume. Although this normally restore CO according to the Frank– Starling mechanism, the
result in the failing heart is volume overload and
increased systemic vascular resistance.
Activation of the SNS would normally restore CO through an increase in heart rate and contractility.
However, in the failing heart, increased heart rate impairs filling and increases myocardial work and oxidative stress, risking sub-endocardial ischaemia.
e) List three classes of drug used to target the deleterious neuroendocrine response to chronic heart failure. (3 marks)
• Angiotensin II receptor blocker OR angiotensin-converting
enzyme inhibitor
• Neprilysin inhibitor (Sacubitril)
• β-blockade
• Diuretics
** Neprilysin is an endopeptidase which metabolises brain natriuretic peptide (BNP), released by the cardiac ventricles in volume
overload. Sacubitril inhibits neprilysin, thus increasing BNP which then acts to promote natriuresis.
f) Specific to cardiac physiology, give four techniques that you would employ during the patient’s intra-operative management to preserve cardiac output and minimise myocardial workload. (4 marks)
• Maintenance of preload/high central venous pressure (CVP
**High CVP to facilitate filling of poorly compliant ventricle.
• Avoid tachycardia To preserve diastolic time.
• Avoid/promptly treat arrhythmia Ensure atrial kick to fill against high LVEDP.
• Maintain contractility/positive inotropy
** May require positive inotropes to achieve this.
• Avoid acute increases in afterload
Question 3. You are asked to see Gareth, a 32-year-old man with known asthma. He has presented with increasing nocturnal dyspnoea over the last three nights and is now being treated in the resuscitation bay of the EmergencyDepartment.A diagnosis of acute severeasthmaismade. a) List four drugs (with doses) used in the management of acute severe asthma. (4 marks)
• Oxygen titrated to saturation
• Salbutamol 5 mg nebulised
• Ipratropium 0.5 mg nebulised
• Hydrocortisone 200 mg/
prednisolone 40 mg
• Magnesium 2 g intravenous
According to the British
Thoracic Society (BTS)
guidelines. Nebulisers
should be driven by oxygen.
b) List six clinical features of life-threatening asthma. (6 marks)
2019 BTS GUIDELINES
○ PEF <33% best or predicted Life-threatening asthma
• SpO2 <92%
• Silent chest, cyanosis, poor respiratory effort
• Arrhythmia, hypotension
• Exhaustion, altered consciousness
Measure arterial blood gases :Markers of severity:
• ‘Normal’ or raised PaCO2 (PaCO2>4.6 kPa; 35 mmHg)
• Severe hypoxia (PaO2 <8 kPa; 60 mmHg)
• Low pH (or high H+)
Book answer **According to the BTS guidelines, a diagnosis of life-threatening asthma may be made if the patient has any ONE of these symptoms.
• Peak expiratory flow rate (PEFR) 33% best of predicted
• SpO2 > 92%
• PaO2 > 8 kPa
• Normal PaCO2 (4.6–6.0 kPa)
• Silent chest
• Cyanosis
• Feeble respiratory effort
• Bradycardia
• Arrhythmia
• Hypotension
• Exhaustion
• Confusion
**Diagnostic criteria of ‘near fatal’ asthma in adults are a raised PaCO2 and/or requiring mechanical ventilation with raised inflation pressures.
Gareth continues to deteriorate. You review him again and diagnose life-threatening asthma. c) State four absolute and four relative indications for intubation and mechanical ventilation in life-threatening asthma. (4 marks)
○ Absolute indications:
• Coma
• Respiratory arrest
• Cardiac arrest
• Severe refractory hypoxaemia
○ Relative indications include:
• Poor response to initial management
• Fatigue
• Somnolence
• Cardiovascular compromise
• Development of a pneumothorax
d) Thepatient is intubated. What ventilator settings would you choose, and why? (4 marks)
• Respiratory rate: 12–14 breaths/
min → prevent gas trapping and
hyperinflation
• PEEP: ≤5 cmH2O → as intrinsic
PEEP is high in acute asthma, the
extrinsic PEEP should be low
• I:E ratio: up to 1:4 → to allow
adequate expiration and prevent
gas trapping
• P max: <35 cmH2O → to prevent
barotrauma (especially
pneumothorax)
e) Despiteoptimal ventilator settings, the patient does not improve. Name two other drugs that may be used in life-threatening asthma when the patient is on a mechanical ventilator. (2 marks)
• Inhaled anaesthetic agent (e.g. sevoflurane)
• Intravenous ketamine
Not acceptable: magnesium – this should have been given prior to intubation.
Question 4. Oscar is a 2-year-old boy brought to the Emergency Department by his parents following an episode of sudden coughing whilst eating3hoursago.On arrival,he has a respiratory rate of 30 breaths/min and evidence of a mild increased work of breathing. On auscultation, you note a localised wheeze on the right-hand side of the chest. Oxygen saturations are 95% in air. a) What is the most likely diagnosis? (1 mark)
Inhaled foreign body/foreign body
aspiration
1 Foreign body (FB)
aspiration most commonly
occurs in 1- to 3-year-olds
(boys > girls). Children of
this age are prone to FB
aspiration because they
• Put objects in their
mouths
• Have less ability to chew
food
b) Apart from increased respiratory rate, state four other features of an increased work of breathing in a child of Oscar’s age. (4 marks)
• Tracheal tug/intercostal and sub- costal recession
• Use of accessory muscles/tripod position
• Seesaw pattern/paradoxical abdominal breathing
• Tachycardia/sweating
• Peripheral/central cyanosis
• Nasal flaring
• Grunting/stridor
c) Give four features that you may see on a chest radiograph with this diagnosis. (4 marks) FBA
• Nil apparent
**The majority of inhaled material is organic in origin and therefore a chest X-ray may fail to demonstrate an abnormality, especially in the first 24 hours.
• Aspirated radio-opaque object (must specify ‘radio-opaque’)
• Pneumothorax
• Consolidation
• Collapse
• Hyperinflation/gas trapping
**The absence of radiographic abnormalities does not exclude the diagnosis of an inhaled FB.
• Mediastinal shift
You opt to wait until Oscar is fasted before taking him to theatre. d) State three advantages and three disadvantages of performing a gas induction with sevoflurane in oxygen for this case. (6 marks
Advantages:
• Avoids need for awake cannulation
• Allows for pre-oxygenation
• Reduced risk of distal movement of FB
• Lessens degree of distal air-trapping
• Allows rapid assessment of ventilation post-retrieval
Disadvantages:
• Difficulty maintaining depth of anaesthesia
• Required depth of anaesthesia to eliminate airway reflexes may cause V̇ /Q̇ mismatch and cardiovascular compromise
• Risk of coughing/patient movement
• Risk of hypercapnia due to resistance once scope inserted
The alternative technique would be IV induction and positive pressure
ventilation.
The advantages of this include:
• Reduced aspiration risk
• Reduced risk of coughing
• Reduced atelectasis
• Optimal oxygenation and ventilation prior to bronchoscopy
• Easier to use IV maintenance as airway and ventilation already controlled
Disadvantages include:
• Necessitates awake cannulation
• May move FB distally
• Unable to assess ventilation post-procedure until cessation of paralysis and anaesthesia
• May increase distal air-trapping
• Harder to manage any IV maintenance therapy as need to maintain spontaneous respiratory effort
e) Name the drug and dose (in mg/kg) that you would use to anaesthetise the airway in Oscar’s case. (2 marks)
Drug: Lignocaine
• The maximum recommended dose of lignocaine (without adrenaline) is usually quoted as 3 mg/kg.
• For airway topicalisation, this may be increased to 4 mg/kg in children as much of the lignocaine is ultimately swallowed.
f) Give three complications that may occur post-operatively specific to this case. (3 marks) FBA
• Infection/abscess
• Laryngeal oedema/stridor
• Pneumothorax/haemothorax
• Respiratory failure/ongoing O2 requirement
Question 5. You are called urgently to review Karen on the postnatal ward. She had an uneventful caesarean section earlier in the day but has collapsed on the ward with fresh blood per vaginam. a) What are the four most common causes of primary postpartum haemorrhage? (4 marks)
• Uterine atony
• Retained products of conception
• Genital tract trauma
• Coagulopathy
A mnemonic for the common causes of PPH is the ‘4 Ts’ – Tone, Tissue, Trauma, Thrombin.
primary postpartum haemorrhage (PPH) is defined as loss of > 500 mL
from the genital tract within 24 hours of delivery.
2017 ACOG redefined PPH as more than or equal to 1000 ml, or blood loss that was accompanied by signs or symptoms of hypovolemia occurring within 24 h after birth, regardless of the mode of delivery.
b) The following table outlines the pharmacological management of obstetric haemorrhage. Complete the missing information. (7 marks)
• Syntocinon intravenous 5 IU
• Tranexamic acid intravenous 1 g 1
• Carboprost intramuscular 250 μg
• Misoprostol per rectum 800 μg (accept 600 μg to 1 mg)
**Hyperthermia and diarrhoea may be seen following administration of misoprostol.
• Ergometrine intramuscular 500 μg (accept intravenous, accept 250 μg)
**Ergometrine should be avoided in patients with pre-eclampsia as it can exacerbate hypertension.
c) List six non-pharmacological methods of managing obstetric haemorrhage. (6 marks)
• Bimanual compression/uterine massage
• Resuscae balloon tamponade/Bakri those to stop the bleeding.
** balloon/Rusche balloon
• B-Lynch suture
• Interventional radiology
• Vessel ligation (internal iliac, uterine, hypogastric, ovarian)
• Hysterectomy
• Aortic compression
The key to successful management is early senior input. Think ahead and act early.
d) In which common medical condition should the administration of carboprost be avoided? (1 marks)
Asthma
List eight clinical manifestations of SCD. (8 marks)
• Haemolytic anaemia
• Occlusive crises, e.g. dactylitis Abdominal pain due to vessel occlusion may be
difficult to distinguish from other causes of acute abdomen.
• Acute chest syndrome
**Defined as a temperature ≥ 38.5°C, chest pain or respiratory distress and
new lobar infiltrates on chest X-ray.
• Stroke
• Aplastic crisis
**Usually precipitated by parvovirus B19 infection.
• Acute splenic sequestration
** Large numbers of RBCs are sequestered in the spleen, causing a sudden drop in haemoglobin and cardiovascular collapse.
• Splenic infarction
*Caused by repeated sickling episodes, makes patients susceptible to encapsulated bacteria.
• Osteomyelitis
**Most common pathogens: salmonella andstaphylococci.
• Priapism
• Avascular necrosis
**Most often of the femoral head.
• Gallstones
**Due to haemolytic anaemia.
• Sickle retinopathy
• Leg ulcers
• Chronic renal failure
c) In the table below, outline the maximum doses of the local anaesthetic agents shown. (4 marks)
Lignocaine: 3 mg/kg without, 7 mg/kg
with
Bupivacaine 2 mg/kg without, 2 mg/kg
with
Ropivacaine 3 mg/kg without, 3 mg/kg
with
Prilocaine 6 mg/kg
Fixed dosing rules do not
account for the wider
clinical context; the
epidural route carries a
greater risk of LA toxicity
than subcutaneous
injection
Question 12. Norman, a 78-year-old man, is listed for an Ivor Lewis oesophagectomy for cancer. He attends for a cardiopulmonary exercise test (CPET). a) Regarding the metabolic equivalent of a task (MET), state the number of METs associated with each of the following. (4 marks) Resting, fasted for >12 hours:______________________________________________ Walking at 2.5 mph on the flat:_____________________________________________ Climbing two flights of stairs without stopping:________________________________ Jogging:_________________
Resting = 1 MET
Walking 2.5 mph = 2.9 METs (accept
3 METs)
Climbing two flights stairs = 4 METs
Jogging = 8 METs (accept 7–8 METs)
A functional capacity of< 4 METs represents poor physiological fitness and is associated with a higher risk of perioperative complications.
