CRQ Paper 10 Flashcards
Question 1.
Eliza, an 8-year-old girl, is unwell and is brought into the Emergency Department (ED) by
a paramedic crew. On arrival at the ED, she has a tonic-clonic seizure.
a) List four causes of seizures in this age group. (4 marks)
a • Epilepsy: either known history
or first fit
• Metabolic: hypoglycaemia, hyponatraemia (maximum 1
mark for metabolic causes)
• Intracranial pathology:
haemorrhage, tumour,
infection (meningitis,
encephalitis, HIV) (maximum 2
marks for intracranial causes)
• Poisoning
Any 4 Two seizures are required
before epilepsy can be
diagnosed.
Not acceptable: febrile convulsion
(typically age 6 months to 5 years)
b) List three seizure types other than tonic-clonic. (3 marks)
• Focal seizure (also known as
partial seizure)
• Absence seizure (also known as
petit mal)
• Atonic seizure (also known as
drop attack)
• Clonic seizure
• Tonic seizure
• Myoclonic seizure
Any 3 The patient may retain
awareness (simple partial
seizure) or lose awareness
(complex partial seizure).
c) Outline your initial patient management. (3 marks) seizure
• ABC assessment
• Confirm clinically that this is a seizure
• Apply oxygen
• Establish IV access
• Blood glucose
• Venous blood gas for Na+
d) State your pharmacological management (with per kilogram doses) of this situation according to the following time frames. (6 marks) child with seizures
At 5 min:
1. ___________________________________________________________________
or 2.__________________________________________________________________
At 15 min:
______________________________________________________________________
At 25 min:
1. ___________________________________________________________________
or 2.__________________________________________________________________
At 45 min:
5 min: Must have drug and per kg
• Midazolam 0.5 mg/kg buccal 1 dose to gain each mark.
• Lorazepam 0.1 mg/kg IV 1
15 min:
Lorazepam 0.1 mg/kg IV 1
25 min:
• Phenytoin 20 mg/kg IV
infusion over 20 min
• Phenobarbital 20 mg/kg IV
over 5 min
45 min:
Thiopentone 4 mg/kg IV (accept
3–6 mg/kg)
e) Which endotracheal tube (ETT) size would you use for this child? (1 mark)
• 6.0 mm uncuffed ETT
• 5.5 mm cuffed ETT
* Formula is (age/4)+4 for uncuffed ETTs, with 0.5 mm subtracted for cuffed ETTs.
Eliza is now successfully intubated, and you need to transfer her for a CT scan. Three full
oxygen cylinders of different sizes are available.
f) What is the volume of oxygen stored within each? (3 marks)
Size CD _______________________________________________________________
Size E _________________________________________________________________
Size F _
Size CD = 460 L (accept 400–600 L)
Size E = 680 L (accept 600–800 L)
Size F = 1360 L (accept
1200–1500 L)
Question 2.
Bob is a 79-year-old man with known coronary artery disease. The surgical team would like
to perform off-pump coronary artery bypass grafting.
a) List four features of a patient’s past medical history that might make an off-pump procedure preferable. (4 marks)
• Aortic disease precluding bypass
• Renal disease
• Ventricular dysfunction
• Diabetes
• Advanced age
• Chronic lung disease
• Previous cerebrovascular accident (CVA)
In off-pump procedures:
• aortic cannulation is not required, which reduces the risk of aortic
dissection or embolisation.
• an aortic cross-clamp is not required, which reduces the risk of
plaque embolism and subsequent CVA.
Patients who are at higher risk of complications from conventional
cardiopulmonary bypass may benefit from off-pump surgery.
b) What is the target activated clotting time (ACT) for off-pump coronary artery bypass
graft surgery? (1 mark)
250–300 s
*A typical dose of heparin to achieve this degree of anticoagulation is 1–2 mg/kg
(100–200 U/kg).
c) In order to work on the posterior and lateral surfaces of the heart, it must be lifted
vertically out of the pericardial sac. Give two physiological reasons why this may cause haemodynamic compromise. (2 marks)
• Need upward blood flow into
vertically positioned ventricle
* A greater filling pressure is required to maintain ventricular filling.
• Vertical position distorts mitral
and tricuspid annuli
* Distortion of annuli can result in significant valvular regurgitation.
d) A decrease in mean arterial blood pressure is common during off-pump coronary artery bypass. List three intra-operative strategies used to restore blood pressure to normal limits. (3 marks)
• Trendelenburg position
• Fluid administration
• Commencement of noradrenaline
• Atrial pacing to a rate of 60 beats/min
*Target mean arterial pressure should be
> 70 mmHg.
Tachycardia is deleterious during off-pump bypass surgery owing to the consequent
increase in myocardial oxygen demand; esmolol or verapamil is often used to decrease
myocardial oxygen demand.
e) Complete the following table regarding these two drugs. (6 marks)
e Esmolol:
• Receptor activity: β1-adrenoreceptor antagonist
• Metabolism: red cell esterases
• Affected phase: phase 4
* Esmolol is highly cardio-selective, has rapid onsetand offset and has a
metabolism independent of liver or renal function. The gradient of phase 4 of the
pacemaker potential is reduced, thus decreasing heart rate.
Verapamil:
• Receptor activity: competitive calcium channel blocker
• Metabolism: hepatic metabolism
• Affected phase: phase 0
* Verapamil is a specific antagonist of the L-type Ca2+ channel, with a particular
affinity for those at the SA and AV nodes.
f) State four reasons why off-pump coronary bypass surgery is considered more ‘cost-
effective’ than cardiopulmonary bypass. (4 marks)
• Requires fewer staff (no perfusionist)
• Reduced transfusion costs
• Reduced length of stay
• Reduced number of ventilated days
• Reduced equipment requirements (no bypass circuit)
Question 3.
You are asked to review Johnny, a 56-year-old man, on the respiratory ward. He
presented to hospital 2 days ago with acute severe pneumonia. An arterial blood gas
reveals type 1 respiratory failure, and you believe he has acute respiratory distress
syndrome (ARDS).
a) List four components of the Berlin definition of ARDS. (4 marks)
• Timing: within 1 week of the start of symptoms
• Chest imaging: bilateral opacities
• Not explained entirely by fluid overload
• PaO2/FiO2 ratio < 39.9 (accept a ratio < 300 when using mmHg) (minimum PEEP of 5 cmH2O)
* Causes of ARDS may be classified as follows:
• Direct causes:
pneumonia, aspiration, lung contusion, fat embolism, drowning, inhalational injury, reperfusion injury.
• Indirect causes: sepsis, multiple trauma, massive transfusion, pancreatitis, cardiopulmonary bypass.
b) List four ventilatory strategies used to prevent further lung injury whilst maintaining oxygenation. (4 marks)
• Ventilation using 6–8 mL/kg tidal volume
• Permissive hypercapnia
• High positive end-expiratory pressure (PEEP)
• Plateau pressure < 30 cmH2O
• Recruitment manoeuvres
• Avoid hyperoxia
* A pH > 7.20 is commonly accepted; the actual PaCO2 is of lesser importance.
Despite optimal management, Johnny’s oxygenation continues to decline, and a decision is
made to reposition him into the prone position.
c) List three effects of the prone position on the respiratory system that aid oxygenation.
(3 marks)
• Improved V̇ /Q̇ ratio
• Increase in functional residual capacity
• Recruitment of atelectatic lung
* Displacement of the heart which compresses surrounding lung tissue
also helps improve V̇ /Q̇ matching.
Two days later, Johnny is discussed at the multi-disciplinary meeting, and it is suggested
that he be considered for extracorporeal membrane oxygenation (ECMO). You are asked to
calculate his Murray score.
d) List the four components used to calculate the Murray score. (4 marks)
• PaO2/FiO2 on 100% O2
• PEEP (cmH2O)
• Compliance (mL/cmH2O)
• Chest X-ray quadrants infiltrated
*Each component scored from 0 to 4.
A Murray score ≥ 3 represents severe
respiratory failure appropriate for referral for extracorporeal membrane oxygenation (ECMO).
e) List four contraindications to ECMO. (4 marks)
• High peak inspiratory pressures > 30 cmH2O for more than 7 days
• High FiO2 ventilation (>0.8) for more than 7 days
• Intracranial bleed
• Any other contraindication to heparinisation
* To be eligible, patients must have a reversible cause of respiratory failure and
should not have a life-limiting comorbidity aside from the acute disease process.
f) What type of ECMO circuit is most commonly used to facilitate gas exchange when
cardiac function is preserved? (1 mark)
Veno-venous circuit
Question 4.
Olivia is a 3-year-old girl weighing 15 kg who is listed for elective day-case strabismus
surgery. She has no other past medical history of note, takes no regular medication and has
no drug allergies.
a) Name two syndromes associated with strabismus. (2 marks)
• Down’s syndrome
• Edward’s syndrome
• Cri du chat
• Goldenhar
• Treacher–Collins
• Smith–Lemli–Opitz
• Crouzon
• Apert
• Pfeiffer
On clinical examination, you hear a cardiac murmur. List three clinical features of an
innocent murmur. (3 marks)
• Soft
• Early systolic
• Varies with position
• No abnormal signs/symptoms (e.g. failure to thrive, syncope, cyanosis)
* A murmur should be investigated prior to surgery in the following situations:
• <1 year old
• Pathological murmurs
(all diastolic, pansystolic, late systolic, loud or
continuous murmurs)
• Any abnormal symptoms or signs
• Abnormal ECG or chest
c) You plan to administer the following pre- and intra-operative medication. Complete the
table. (5 marks)
• Paracetamol: 15 mg/kg (accept 20 mg/kg)
• Ibuprofen: 5 mg/kg
• Glycopyrrolate: 4–8 μg/kg
• Ondansetron: 0.1–0.15 mg/kg
• Dexamethasone: 0.15 mg/kg
* Strabismus surgery can cause severe pain. A
common analgesic regimen is topical local anaesthetic, opioid analgesia, e.g. fentanyl, paracetamol and ibuprofen; multimodal analgesia should be continued into the post-operative period. The use of opioids increases the risk of
post-operative nausea and vomiting (PONV), and
antiemetics are essential.
d) During her strabismus surgery, Olivia suddenly becomes bradycardic. Name the reflex
causing this bradycardia, and state the specific afferent and efferent nerves involved.
(3 marks)
Reflex: oculocardiac
○ The relay for the oculocardiac reflex is via
the sensory nucleus in the fourth ventricle.
°Afferent: ophthalmic division (V1) of trigeminal nerve
° Efferent: vagus nerve
* Children with a positive oculocardiac reflex are more likely to develop PONV than those with no measurable reflex. It has been postulated that preventing the oculocardiac reflex may reduce the incidence of PONV.
Olivia has met the criteria for day-case surgery. List four patient-related factors and three
social factors that would exclude a paediatric patient from day-case surgery. (7 marks)
○ Patient-related factors:
• Term baby < 1 month in age
• Preterm or ex-preterm baby < 60 weeks post-conception age
• Poorly controlled systemic disease
• Inborn errors of metabolism (including diabetes mellitus)
• Complex cardiac disease or cardiac disease requiring investigation
• Sickle cell disease (not trait)
• Active infection (especially of respiratory tract)
* Anaesthetic/operative factors that preclude
paediatric day-case surgery include:
• Inexperienced surgeon or anaesthetist
• Prolonged procedure
• Opening of a body cavity
• High risk of perioperative haemorrhage/fluid loss
• Post-operative pain unlikely to be relieved by
oral analgesics
Social factors:
• Parent unable to care for the child at home post-operatively
• Poor housing conditions
• No telephone
• Excessive journey time from home to the hospital (>1 hour)
• Inadequate post-operative transport arrangement
• Difficult airway (including obstructive sleep apnoea)
• Malignant hyperpyrexia susceptibility
• Sibling of a victim of sudden infant death
syndrome
Question 5.
Hazra is a 34-year-old primigravida who is 38 weeks pregnant. She presents to the maternity
unit with a 1-week history of increasing shortness of breath, ankle swelling and fatigue.
a) Which three criteria must be met to make a diagnosis of peripartum cardiomyopathy
(PPCM)? (3 marks)
• Development of heart failure within the last month of pregnancy or up to 5 months following delivery
○ PPCM closely resembles dilated cardiomyopathy.
• Absence of another identifiable cause of heart failure
• Left ventricular systolic dysfunction on
echocardiogram/ejection fraction < 45%
List three changes you may see on an ECG in a normal pregnancy. (3 marks)
• Left axis deviation
• T-wave inversion (lateral leads/III)
• Presence of Q waves (III/aVF)
• Atrial/ventricular ectopics
• Sinus tachycardia
* The heart is physiologically dilated and displaced in both cephalad and lateral
directions.
Increasing circulating vasopressors and
diaphragmatic changes may play a role.
Hazra undergoes a caesarean section under combined spinal–epidural anaesthesia.
d) List five principles of intra-operative management in this case. (5 marks)
• Invasive arterial monitoring
• Maintain preload/left lateral tilt
to avoid aortocaval
compression
• Avoid tachycardia
• Avoid increases in afterload
• Maintain sinus rhythm
• Maintain contractility
• Avoid hypotension/carefully titrated spinal block
• Avoid fluid overload/cautious intravenous infusion/ furosemide on delivery
*Vaginal delivery is favoured with low dose epidural analgesia.
Effective analgesia will help prevent tachycardia.
Assisted second stage can reduce cardiovascular instability.
e) For each of the following uterotonics, state two deleterious effects that may occur in
patients with PPCM. (4 marks)
Oxytocin:
1. ___________________________________________________________________
2. ___________________________________________________________________
Ergometrine:
Oxytocin:
• Decrease in systemic vascular resistance/compensatory tachycardia
• Coronary vasoconstriction
* Oxytocin must be slowly titrated.
Ergometrine:
• Coronary vasoconstriction
• Pulmonary vasoconstriction
• Systemic vasoconstriction
*Ergometrine should be avoided in patients with PPCM.
Question 6.
Ada, a 62-year-old woman, is listed for excision of a large ovarian mass through a lower-
midline laparotomy. She has a history of chronic back pain, and her regular medication
includes pregabalin 150 mg bd and modified-release oxycodone 40 mg bd. She has recently
had a spinal cord stimulator (SCS) inserted.
a) List two indications for SCS insertion. (2 marks)
• Failed back surgery syndrome
• Complex regional pain syndrome
• Neuropathic pain secondary to peripheral nerve damage
• Ischaemic pain associated with peripheral vascular disease
These are the four indications recommended by the National Institute for
Health and Care Excellence (Technology appraisal guidance TA159).
Not acceptable: chronic back pain
b) List two contraindications to spinal cord stimulator insertion. (2 marks)
• Psychological unsuitability:
personality disorder, significant depression/anxiety
• Uncontrolled bleeding/anticoagulation
• Systemic or severe sepsis
• Implanted cardiac devices: demand pacemaker or defibrillator
• Immunosuppression
c) What are the two component parts of a spinal cord stimulator? (2 marks)
• Stimulator leads: 4w–8 electrodes, either paddles (surgically placed) or catheters
(percutaneously placed)
• Pulse generator: external (for spinal cord stimulator trial) or
implanted
* The pulse generator is usually implanted
subcutaneously in the anterior abdominal wall, lateral chest wall, gluteal or
infraclavicular areas.
d) State two perioperative implications of the spinal cord stimulator. (2 marks)
• Avoid unipolar diathermy if possible
• If not possible, place neutral plate so that SCS components are outside the electrical field of diathermy
• Risk of damaging/causing infection of leads with neuraxial blockade
• Care with patient positioning/padding of SCS pulse generator
* There is no need to give patients antibiotic prophylaxis specifically due
to the presence of an SCS.
e) List four methods that utilise local anaesthesia which may be used to manage this
patient’s post-operative pain. (4 marks)
• Rectus sheath block/catheters
• Bilateral transverse abdominis
plane block/catheters
• Wound catheters
• Surgical infiltration of the
wound
• Lignocaine infusion
Any 4 Lignocaine infusions are
increasingly commonly
used for intra-operative
analgesia. An ongoing
lignocaine infusion
mandates a bed in a higher
care area.
Not acceptable: neuraxial
techniques, due to presence of SCS
The surgery was complicated by bowel injury, and a primary anastomosis was performed.
Despite administering intra-operative paracetamol and parecoxib and using a regional anaesthetic technique, Ada has severe pain in the post-anaesthesia care unit.
f) List, with doses, three non-opioid analgesics which could be used in this case. (3 marks)
• Clonidine 1 μg/kg intravenous
• Ketamine 0.2–0.75 mg/kg intravenous
• Lignocaine 1.5 mg/kg intravenous
g) Ada is expected to be nil by mouth for the next 2 days. List three early symptoms or signs
of opioid withdrawal. (3 marks)
• Agitation/restlessness
• Anxiety
• Muscle aches
• Insomnia
• Rhinorrhoea/tears
• Sweating
• Yawning
• Tachycardia/tachypnoea
Any 3 Symptoms such as goose
bumps, dilated pupils and
abdominal cramps are later
symptoms.
What are the ratios of conversion from oral oxycodone into oral morphine and oral morphine into intravenous morphine? (2 marks)
• Oral oxycodone:oral morphine
ratio is 1: 2
• Oral morphine:intravenous morphine ratio is 3:1
**The different opioid equivalence of oral and intravenous morphine is due to first-pass
Question 7.
Derrick, a 68-year-old man, is listed for a laparoscopic anterior resection for a recently
diagnosed bowel cancer. He has a past medical history of hypertension.
a) List two cytokines thought to initiate the surgical stress response. (2 marks)
• Interleukin 1 (IL-1)
• Interleukin 6 (IL-6)
• Tumour necrosis factor alpha (TNF-α)
** Cytokines contribute to the
haematological consequences of the surgical stress response, including
• hypercoagulability
• fibrinolysis.
b) For each of the following hormones, state two phphysiological effects of their release
related to the surgical stress response. (4 marks)
Cortisol:
Growth hormone:
Cortisol:
• Increased protein breakdown
• Promotes gluconeogenesis
• Increased lipolysis
• Peripheral insulin resistance/hyperglycaemia
• Anti-inflammatory activity/
immunomodulatory effect
Growth hormone:
• Increased protein synthesis
• Reduced proteolysis
• Promotes lipolysis
• Anti-insulin effect
• Glycogenolysis
**Other hormones implicated in the surgical stress response include the
following:
• Antidiuretic hormone (increased secretion)
• Insulin (reduced secretion)
• Adrenocorticotrophic hormone (increased secretion)
• β-endorphin (increased secretion)
• Prolactin (increased secretion).
The other major contributor in the surgical stress response is the activation of
the sympathetic nervous system.
A pre-operative full blood count has revealed a microcytic anaemia with a haemoglobin of107 g/L.
Derrick’s surgery is listed for 6 weeks’ time.
c) What are the two treatment options? Give one advantage and one disadvantage for eachoption. (6 marks)
Option 1: Oral iron therapy
Advantages:
• Ease of administration
• Low cost
Disadvantages:
• Poor tolerance/gastrointestinal
side effects
• Poor bioavailability
• Limited time for effect
Option 2: Intravenous iron therapy
Advantages:
• More effective rise in haemoglobin
• Adequate time frame for effect
Disadvantages:
• Requires hospital admission
• Risk of anaphylaxis
Anaemia may be corrected by allogenic transfusion, but it is now established that transfusion itself is
associated with increased perioperative morbidity and mortality.
Treatment of pre-operative anaemia should be directed
at correcting the underlying cause. Correcting anaemia before surgery reduces perioperative transfusion rates, post-operative
infective and ischaemic complications and length of hospital stay. It also
conserves blood stocks and is associated with cost
savings.
Derrick is admitted on the day of surgery as per the enhanced recovery pathway. Once he is
anaesthetised, you insert an oesophageal Doppler probe.
d) How would you use this cardiac output monitor for goal-directed fluid therapy? (3 marks)
• Administration of a 250 mL
crystalloid fluid bolus
1
• Observation of changes in
stroke volume over subsequent
10 min
1
• An increase in stroke volume of
< 10% means a further bolus of
IV fluid is not indicated. An
increase in stroke volume of
> 10% means a further fluid
bolus should be administered
e) Aside from goal-directed fluid therapy, state two further elements of your intra-
operative care for Derrick in the context of an enhanced recovery pathway. (2 marks)
• Use of short-acting anaesthetic
agents
*There is little evidence to favour one anaesthetic technique over another, but
the general principles of enhanced recovery support the use of agents that have minimal post-operative hang-over and effects on
gastrointestinal motility.
• Multi-modal analgesia/avoidance of long-acting opioids
• Temperature homeostasis
• Risk stratification/prophylaxis against post-operative nausea and vomiting
•Total intravenous anaesthesia can be used and may play an increasing role in cancer surgery in the future.
• Consideration of regional anaesthesia
*Neuraxial blockade offers advantages over other regional techniques, such as
• reduction in the duration of ileus,
• reduced blood loss,
• reduction in post-operative pulmonary
complications, including pulmonary embolism
• modification of the stress response.
However, potential disadvantages include
• complications associated with their
insertion
• reduced mobilisation
• excessive fluid administration to combat hypotension.
f) State three features of post-operative care for a patient, such as Derrick, on an enhanced
recovery pathway. (3 marks)
• Multi-modal analgesia/ avoidance of excessive intravenous opiates
• Early discontinuation of intravenous fluids/early enteral intake
• Early removal of drains/ catheters
Another vital part of enhanced recovery is audit to review compliance with the pathway.
• Early mobilisation
• Multi-disciplinary approach to post-operative care
• Telephone follow-up on discharge
Question 8.
John is a 31-year-old cyclist who has suffered major injuries following a road traffic
collision. On arrival at the Emergency Department, he is noted to be tachycardic and
hypotensive with a tense abdomen. A trauma CT reveals a ruptured spleen and multiple
liver lacerations. He is listed for an emergency laparotomy, and you have activated the major haemorrhage protocol.
a) Give a definition for ‘major haemorrhage’ and a definition for ‘massive transfusion’.
(2 marks)
Major haemorrhage
• Loss of total blood volume within 24 hours
• Loss of 50% blood volume in < 3 hours
• Bleeding in excess of 150 mL/min
• Bleeding leading to a systolic blood pressure of < 90 mmHg and pulse of > 110 beats/min
○ There is no one accepted definition for either major haemorrhage or massive transfusion.
Massive transfusion
• Transfusion of ≥10 red blood cell (RBC) units within 24 hours
• Transfusion of >4 RBC units within 1 hour, with anticipation of continued need for blood product support
• Replacement of > 50% of the total blood volume by blood products within 3 hours
b) List the three components of the lethal triad of trauma (3 marks), and for each component, give one deleterious consequence specific to the coagulation process. (3 marks)
○ Component: metabolic acidosis
Consequence:
• pH affects activity of factors V, VIIa and X
• Acidosis inhibits thrombin
○ Component: hypothermia
Consequence:
• Decreases platelet activation
• Increases platelet sequestration in liver and spleen
• Reduces functions of factors XI and XII
• Inhibits fibrinolysis
○ Component: acute coagulopathy
Consequence:
• Systemic anticoagulation
• Consumption of coagulation factors
• Hyperfibrinolysis
° Early trauma-induced coagulopathy (ETIC) is
associated with systemic anticoagulation and
hyperfibrinolysis.
° Tissue injury from trauma releases local and systemic tissue factor which activates coagulation pathways.
• The initiation results in massive consumptive coagulopathy leading to a consumptive disseminated intravascular coagulation-like syndrome, most commonly seen in patients with severe head injury or
extensive muscle damage.
Intra-operatively, John continues to bleed, and you administer blood products.
c) For each listed blood product, state the target value which would indicate adequate
transfusion. (4 marks)
Packed red blood cells:
Cryoprecipitate:
Platelets:
• RBCs: haemoglobin >80 g/L (accept 70–90 g/L)
• Fresh frozen plasma:
international normalised ratio (INR) < 1.5/prothrombin time < 15 s.
• Cryoprecipitate: fibrinogen > 1.5 g/L Fibrinogen target is > 2 g/L in obstetric haemorrhage
• Platelets: platelet count > 75 ×
d) Using the sub-headings provided, list the complications of massive transfusion. (6 marks)
Transfusion reactions:
Metabolic complications:
Transfusion reactions:
• Allergic reaction (accept urticaria anaphylaxis)
• Haemolytic transfusion reaction
• Febrile non-haemolytic transfusion reaction
Other complications include the following:
• Infection
• Transfusion-associated circulatory overload
(TACO) (infants and patients with pre-existing cardiac disease are at increased risk)
• Air embolism: rare and potentially fatal
complication of rapid infusor use.
Immunological reactions:
• Transfusion-related acute lung injury (TRALI)
• Transfusion-related immunomodulation (TRIM)
• Transfusion-associated graft vs host disease (Ta-GVHD)
• Post-transfusion purpura (PTP)
Metabolic complications:
• Hypocalcaemia
* Hypocalcaemia due to citrate overload.
• Hypomagnesaemia
• Hyperkalaemia
* Hyperkalaemia is due to haemolysis of RBCs duringnstorage, irradiation or both.
• HypokalaemiaHypokalaemia may occur
because of K+ re-entry into transfused RBCs
• Metabolic alkalosis
*Metabolic alkalosis may occur because of citrate overload.
• Metabolic acidosis
* Metabolic acidosis occurs because of hypoperfusion, liver dysfunction and citrate
overload.
• Hypothermia
* Hypothermia occurs through conduction:
infusion of cold blood products. A blood warmer should always be used.
What effect does tranexamic acid have on the coagulation cascade, and what dose would
you use in an adult major trauma patient? (2 marks)
Effect
Dose:
Pharmacodynamic effect:
Competitive inhibitor of conversion of plasminogen to active plasmin
Dose:
• 1 g intravenous bolus, followed by
infusion of a further 1 g over 8
hours
Question 9.
You attend the departmental morbidity and mortality meeting where recent critical incidents are reviewed. Two corneal abrasions are reported, and preventative steps are discussed.
a) List three causes of corneal abrasion under general anaesthesia (3 marks) and three physical measures you can take to help prevent corneal abrasions from occurring. (3 marks)
Causes of corneal abrasion:
○ Causes of corneal abrasion:
• Direct trauma
• Exposure keratopathy
• Chemical injury
Physical prevention measures:
• Taping of the eyelid
• Instillation of ointment
• Bio-occlusive dressings
• Use of non-toxic antiseptic
○ Clinical features of corneal abrasions are pain, gritty sensation, redness, tearing and photophobia.
○ The diagnosis may be confirmed with fluorescein staining and slit lamp examination.
○ Treatment includes lubricants and topical antibiotics. Occasionally
patching of the eye or bandage lens is required.
Liz discussed a case of common peroneal nerve palsy after prolonged surgery in the lithotomy position which had led to legal action.
b) List three clinical features of common peroneal nerve palsy. (3 marks)
Weakness of dorsi flexion
• Foot drop
• Weakness of eversion
• Weakness of extensor hallucis longus
• Paraesthesia over the dorsal aspect of the foot/lower lateral part of the leg
Common peroneal nerve palsy is classically described following surgery
in the lithotomy position and is due to pressure on the common peroneal nerve as it passes in close proximity to the head of the fibula.
Aside from common peroneal nerve injury, list the two most common nerve injuries
associated with general anaesthesia. (2 marks)
• Ulnar nerve injury 1
• Brachial plexus injury
Jim presented a new guideline for the management of accidental dental trauma. The pathway starts with the pre-operative identification of patients at high risk of dental injury.
d) List four steps that you can take to mitigate the risk of dental injury in a patient with poor dentition planned to undergo lower limb surgery. (4 marks)
• Pre-operative dental review
• Use laryngeal mask airway (LMA) over an endotracheal tube
• Use regional anaesthesia/neuraxial blockade
• Blind nasal intubation
• Bite block
• Deep extubation
• Senior operator
If a tooth is avulsed, relocate it as soon as possible and apply pressure or a splint. Apologise and explain to patient, offer analgesia and refer to a dentist.
The meeting ends with an audit presentation by a junior trainee on the incidence of post-operative sore throat.
e) List five factors that increase the risk of a post-operative sore throat. (5 marks)
• Larger diameter endotracheal tubes
• Poor endotracheal insertion technique (accept trauma)/ difficult intubation
• High endotracheal cuff pressures
• Duration of anaesthesia
• Use of nasogastric tubes
• Use of non-humidified breathing systems
Question 10.
Gwendoline is an 87-year-old woman who has been admitted with a fractured neck of femur following a fall at home. She has a background history of hypertension and atrial fibrillation, for which she takes warfarin.
a) According to AAGBI guidelines, within what time period should surgery for hip fracture be performed? (1 mark
Less than 36–48 hours
* Surgery should be performed within 48 hours of hospital admission after
hip fracture.
○ A target of 36 hours was introduced in England and Wales in April 2010.
b) List four pre-operative investigations that are indicated based on the clinical history provided above. (4 marks)
• Full blood count
• Urea and electrolytes
• Coagulation screen/international normalised ratio (INR)
• Group and save/hold
• Electrocardiogram (ECG)
** A coagulation screen is only required where clinically indicated (e.g. patient taking oral anticoagulants).
Chest X-ray is only indicated in specific circumstances, e.g. newly
diagnosed cardiac failure or suspected pneumonia.
On further examination, you notice that Gwendoline has an ejection systolic murmur. She is not known to have valvular heart disease.
c) Give two findings from Gwendoline’s history and clinical examination that would indicate the need for echocardiography prior to anaesthesia. (2 marks)
• Breathless at rest/on minimal exertion
• A history of angina on exertion
• Unexplained syncope
• A slow rising pulse
• Absent second heart sound
* Echocardiography is also indicated if there is evidence of left ventricular
hypertrophy on ECG without a history of hypertension.
d) State three acceptable reasons for delaying surgery for acute hip fracture patients. (3 marks)
• Haemoglobin concentration < 80 g/L
• Plasma sodium < 120 mmol/L or > 150 mmol/L
• Plasma potassium < 2.8 mmol/L or > 6.0 mmol/L
• Uncontrolled diabetes
• Uncontrolled or acute onset left ventricular failure
• Chest infection with sepsis
• Reversible coagulopathy
• Correctable cardiac arrhythmia with a ventricular rate > 120 beats/min
The AAGBI gives the following as unacceptable reasons to delay surgery:
• Lack of facilities or theatre space
• Awaiting echocardiography
• Unavailable surgical expertise
• Minor electrolyte abnormalities
Due to her ejection systolic murmur, you opt to perform the procedure under general
anaesthesia.
e) Aside from AAGBI standard monitoring and the use of an arterial line, state two other
monitoring devices you would consider utilising intra-operatively; give a reason for
each. (4 marks)
Monitoring device 1:_____________________________________________________
Clinical reason:_________________________________________________________
Monitoring device 2:_____________________________________________________
Clinical reason:__
• Device: cardiac output monitor (accept oesophageal Doppler,
LiDCO, etc.)
• Reason: to provide goal-directed fluid therapy/improve haemodynamic performance
• Device: depth of anaesthesia monitor (accept bispectral index, E-entropy, etc.)
• Reason: avoid potential cardiovascular depression from excessive anaesthesia
• Device: central venous pressure monitoring
• Reason: guide intra-operative fluid therapy (do not accept for drug delivery)
• Device: cerebral oxygen saturation monitoring
• Reason: reduce post-operative cognitive dysfunction through early recognition and management of reduced intra-operative cerebral oxygen
saturations
Gwendoline’s international normalised ratio is 1.4. You opt to perform a psoas compart-
ment block to supplement her analgesia.
f) Give three potential complications specific to this peripheral nerve block. (3 marks)
f • Damage to abdominal viscera
• Retroperitoneal haematoma
• Psoas abscess
• Epidural spread
• Intrathecal injection
Any 3 Unlike a psoas
compartment block, a
femoral nerve⁄fascia iliaca
block does not reliably block
the obturator nerve.
However, a femoral nerve/
fascia iliaca block is more
amenable to ultrasound-
guided placement and still
significantly reduces post-
operative analgesic
requirements
How long after her surgery would you re-instigate Gwendoline’s warfarin therapy?
(1 mark
6–24 hours 1 Some centres re-instigate
warfarin therapy on the day
of surgery.
If Gwendoline had been a candidate for spinal anaesthesia, what two modifications could you have made to your technique to reduce the risk of intra-operative hypotension? (2 marks)
• Utilising a lower dose of intrathecal bupivacaine
• Using intrathecal fentanyl to facilitate a reduced dose of intrathecal bupivacaine
• Using hyperbaric bupivacaine with the patient positioned laterally (fractured hip lowermost)
Question 11.
a) Describe the molecular structure of adult haemoglobin (Hb). (3 marks)
a • Four polypeptide chains/two
alpha and two beta chains
• Four haem moieties/porphyrin
rings with iron atoms
• Iron in ferrous state
• Chains bound together by
hydrogen bonds
Any 3 In adults 95% of
haemoglobin (Hb) exists in
the form of HbA1
containing two alpha and
two beta chains. Foetal Hb
consists of two alpha a
b) Describe how oxygen (O2) binds to Hb (2 marks). Explain the term ‘cooperative binding’. (1 mark)
• Four polypeptide chains/two alpha and two beta chains
• Four haem moieties/porphyrin rings with iron atoms
• Iron in ferrous state
• Chains bound together by hydrogen bonds
In adults 95% of haemoglobin (Hb) exists in the form of HbA1 containing two alpha and two beta chains. Foetal Hb consists of two alpha and
two gamma chains.
List four factors that enhance the binding of O2 to adult Hb. (4 marks)
Oxygen (O2) binding:
• O2 forms a reversible bond to ferrous iron in Hb
• There are four O2 binding sites/four O2 molecules bind
• Each ferrous iron binds a molecule of O2/each Hb molecule binds four O2
molecules
** Cooperative binding is explained by allosteric modulation: when O2 binds
to Hb, the two beta chains move closer together and the haem moieties adopt a ‘relaxed’ state which has an increased affinity for O2.
** When O2 dissociates from Hb the ‘taut’ state is favoured, reducing Hb’s
affinity for O2.
○ Cooperative binding:
° Binding of an O2 molecule to Hb increases Hb’s affinity for O2, facilitating the uptake of additional O2 molecules
Hypoxia can be defined as a deficiency in O2 supply or the inability to utilise O2.
d) Define the four classes of hypoxia. (4 marks)
• Hypoxaemic hypoxia: due to
reduced PaO2
1 Hypoxaemic hypoxia has a
number of causes, e.g.
• inadvertent low
inspired O2
• hypoventilation
• V̇ /Q̇ mismatch
• diffusion impairment.
• Anaemic hypoxia: PaO2 is
normal, but oxygen carrying
capacity is reduced
1 Anaemic hypoxia may be
due to anaemia or carbon
monoxide poisoning.
• Stagnant hypoxia: normal
arterial oxygen content,
circulatory failure leading to
inadequate oxygen delivery
1 Stagnant hypoxia may be
seen in cardiogenic shock.
• Histotoxic/cytotoxic hypoxia:
normal arterial oxygen content
and delivery to tissues, but an
inability of tissues to utilise O2
at a cellular level
1 Cyanide inhibits
cytochrome c oxidase in the
mitochondrial electron
transport chain, resulting
in histotoxic hypoxia.
e) List the three forms in which carbon dioxide is transported in the blood. (3 marks)
• Dissolved 1 CO2 diffuses into red blood
cell, combines with water to
form carbonic acid
(catalysed by carbonic
anhydrase) which
dissociates to form
bicarbonate. Bicarbonate
diffuses out of red blood
cells and is carried in the
plasma.
f) Name the enzyme that is essential in facilitating the transport of carbon dioxide. (1 mark)
Carbonic anhydrase
g) What is the Haldane effect? (1 mark) What is its relevance in the transport of carbon
dioxide? (1 mark)
Haldane effect:__________________________________________________________
Relevance
○ Haldane effect: The double Haldane effect describes how maternal
uptake of CO2 increases whilst foetal CO2 affinity decreases, enhancing the
transfer of CO2 from foetal to maternal circulations.
○ Increased ability of deoxygenated haemoglobin to carry carbon dioxide
Relevance:
• In the tissues, increases affinity for carbon dioxide
• In the lungs, decreased affinity facilitates removal of carbon dioxide
Question 12.
Gillian is a 54-year-old woman listed for vocal cord polypectomy. The surgeons have informed you that the procedure will involve the use of LASER.
a) What does the acronym LASER stand for? (1 mark)
○ Light Amplification by Stimulated Emission of Radiation
• Albert Einstein published the theoretical basis for laser in 1917, but it was
only in 1960 that the first functioning laser was constructed.
b) State the three characteristic features of laser light. (3 marks)
Monochromatic
° Monochromatic: consisting of a single wavelength or colour.
Coherent
° Coherent: photons are in phase.
Collimated
° Collimated: photons are almost in parallel (aligned), with little divergence from the point of origin
c) Provide definitions for the following terms implicated in the production of laser light.
(3 marks)
Spontaneous emission:___________________________________________________
Stimulated emission:_____________________________________________________
Population inversion
○ Spontaneous emission = photon is released from an electron that has spontaneously returned to ground state from a higher energy state
○ Stimulated emission = a photon collides with an electron in a higher
energy orbit, causing a photon to be released as the electron decays
back to ground state
** Stimulated emission is provoked in a lasing medium through the use of
reflective mirrors which reflect photons back into the lasing medium, encouraging further collision. The photons are released in phase and in the
same direction as the stimulating photon.
○ Population inversion: where more electrons exist in higher excited states than in lower unexcited states
* Population inversion is achieved by continuous input from the energy pump (continuous wave laser) or by intermittent pumping (pulsed wave laser).
d) Complete the following table regarding common medical lasers and their applications
in clinical practice. (3 marks)
i) Carbon dioxide (CO2)
○ A CO2 laser utilises a photo-thermal effect, rapidly heating tissues. Depending on the exposure time, tissue vapourisation (ablation), coagulation or both may occur.
ii) Accept lithotripsy, endoscopic sinus surgery or tissue ablation
○ Holmium:YAG laser utilises a photo-mechanical effect. It causes an
extremely intense but brief pulse of laser. This results in explosive expansion of the tissue or water within the renal calculi, causing photoacoustic disruption.
iii) Accept: excimer or argon fluoride
○ These lasers break down covalent bonds in protein molecules (photodissociation), resulting in non-thermal ablation.
e) List two safety features of a laser-resistant endotracheal tube. (2 marks)
• Saline filled cuff
• Methylene blue/dye-filled cuff
• Twin distal cuffs
• PVC tube wrapped with self-adhesive, non-reflective metal tape
** Cuffs of endotracheal tubes are vulnerable to rupture by laser beams. If a cuff inflated with air is ruptured, it allows a massive leak of anaesthetic gases and provides a richer environment for ignition.
f) List three precautions which are taken to protect theatre staff from injury when using laser light. (3 marks)
• Protective goggles (glasses/spectacles not acceptable, as they do not give reliable peripheral visual field protection)
** The protective eyewear must correspond to the wavelength of laser light being used.
• Divergent laser beam
** To reduce the risk of focussed laser light striking the retina.
• Matt-black surgical instruments
• Appropriately trained designated laser safety officer
** To minimise reflection from the main laser beam.
• ‘Laser in use’ signage/locked theatre doors/theatre windows covered
**To prevent accidental injury to passers-by
• Non-water based fire extinguisher available
g) Despite safety precautions, an airway fire occurs. Give five specific management steps that you would immediately take. (5 marks)
• Declare incident/call for help
• Discontinue use of laser
• Stop ventilation/discontinue oxygen source
• Remove the burnt endotracheal tube
• Douse the operative site with water
• Reinstate ventilation with bag–mask ventilation or re-intubation using room air
• Perform bronchoscopy to determine degree of thermal injury
**Further (non-immediate) management may include:
• Tracheostomy
• Steroid therapy to treat inflammation
• Antibiotic therapy
• Transfer to critical care for ventilatory support if concerned about upper airway swelling or lung injury.
Risk factors for
• Hypertensive disorders
• Maternal age > 30 years
• Multiparity
• Multiple pregnancy
• Obesity
• Cocaine use
• Afro-Caribbean descent
factors that shift the adult oxyhaemoglobin dissociation curve to the left.
• Increased pH/alkalosis
• Reduced PaCO2
• Reduced 2,3- diphosphoglycerate
• Reduced temperature
• Carboxyhaemoglobin
• Methaemoglobinaemia
Any 4 This question is looking for factors that shift the adult oxyhaemoglobin
dissociation curve to the left.
Not acceptable: foetal Hb, as the question asks specifically about adult Hb
