• MRCS Part A - Sep 2019 Exam
A 25-year-old man sustained a stab wound to the lateral aspect of the thigh. The police report the weapon used was a homemade knife. After initial assessment and resuscitation, computed tomography (CT) imaging does not demonstrate femoral vessel disruption but evidence of a superficially retained knife fragment.
What is the most appropriate next step in his management? Fragment removal and discharge
Wound closure in the Accident and Emergency Department
Patient can be discharged without the need for any interventionSurgical exploration of the femoral vesselsTetanus prophylaxis, antibiotics and fragment removal and wound care
Explanation
Tetanus prophylaxis, antibiotics and fragment removal and wound care
The wound should be treated as contaminated, therefore the foreign body should be removed in a safe, but timely manner, antibiotic cover provided and appropriate wound care delivered. Furthermore, tetanus should always be given after any penetrating injury if the patient has not been immunised in the past 10 years.
Fragment removal and discharge
While the fragment does require removal, additional steps are required such as tetanus cover, antibiotics and good wound care, to prevent complications.
Wound closure in the Accident and Emergency Department
The fragment will require removal before wound closure otherwise it will become a focus for infection and further complications.
Patient can be discharged without the need for any intervention
This patient will clearly require some intervention to remove the fragment, as such, this is incorrect.
Surgical exploration of the femoral vessels
As the injury is in the lateral aspect of the thigh it is anatomically not a concern for major blood vessel trauma to the femoral vessels, furthermore the computed tomography (CT) report does not demonstrate and disruption. The wound may or may not require surgical
exploration in theatre depending on the location of the fragment. The patient will also require antibiotic and tetanus cover due to the contaminated nature of the wound.
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• MRCS Part A - Sep 2019 Exam
A 12-year-old child has tibia and fibula fractures following a fall from a swing. The fracture is reduced and placed in an above-knee plaster in the Accident and Emergency Department. What is the most reliable clinical feature for compartment syndrome in this alert patient?
Compartment pressures in excess of 30–35 mmHg in a normally perfused patient Loss of dorsalis pedis and posterior tibial pulses on Doppler examination
Severe pain with passive flexion of the foot Palpation of tense swollen compartment Sensory or motor nerve deficit
Explanation
Severe pain with passive flexion of the foot
Compartment syndrome, a devastating early complication of lower limb fractures, occurs when the capillary perfusion pressure falls below the tissue perfusion pressure. This leads to necrosis of the muscles and nerves in the enclosed compartment. The most significant and reliable clinical sign, however, is severe pain in response to passive stretch of the ischaemic muscles. Pain is deep and aching in nature. The sensory nerve fibres are more susceptible to ischaemia than the motor fibres and hence there is loss of sensation before paralysis of the affected group of muscles. Up to 45% of all cases of compartment syndrome are caused by tibial fractures. It is more common in patients with open tibial fractures compared to closed tibial fractures, probably reflecting the severity of the injury. Although commonly caused by trauma, it can also occur following crush injury, massive
haemorrhage, gun shot injuries, deep burns, electrical injuries, restricting tourniquets and fluid extravasation; chronic compartment syndrome has been reported following splints, casts and dressings, military antishock trousers, drug/alcohol abuse, coma, gastrocnemius or peroneus muscle tear and snake envenomation. Areas of muscle may infarct giving rise to rhabdomyolysis, hyperphosphataemia, hyperkalaemia, high uric acid levels and
metabolic acidosis; acute renal failure is a well recognised complication of untreated compartment syndrome.
Many surgeons now use compartment pressures in excess of 30–35 mmHg in a normally perfused patient as an indication for open compartment fasciotomy. However, in a haemodynamically unstable or a shocked patient, a lower threshold is indicated.
Fasciotomy should be undertaken if the difference between the diastolic pressure and the measured compartment pressure is less than 30 mmHg (eg, if the diastolic pressure falls to 50 mmHg, fasciotomy should be undertaken even if the compartment pressure is only 20 mmHg).
Loss of dorsalis pedis and posterior tibial pulses on Doppler examination
Peripheral pulses including the dorsalis pedis and posterior tibial are normal during the early phases of development of compartment syndrome (as it is the microvasculature that is initially affected); loss of peripheral pulses is usually a late and sinister sign that suggests imminent tissue ischaemia.
Palpation of tense swollen compartment
While compartment syndrome may give rise to a tense, swollen and red compartment, it is unreliable and non-specific absence of this sign does not exclude compartment syndrome. Sensory or motor nerve deficit
If left untreated sensory or motor deficient will occur, however, the aim with compartment syndrome is to undergo fasciotomy before the development of neurological deficient which would indicate significant tissue ischaemia and lasting damage
• • • • •
A 19-year-old man is stabbed in the back and has some neurological changes. Imaging confirms he has suffered a left lateral hemisection of the spinal cord at the T5 segment. Which one of the following findings is most likely?
Loss of ipsilateral ankle jerkLoss of pain in the ipsilateral footBabinski sign in the ipsilateral footPreservation of fine touch sensation in the ipsilateral footWasting of the contralateral quadriceps muscle
Explanation
Babinski sign in the ipsilateral foot
Lesions involving hemisection of the cord may cause an ipsilateral loss of fine touch and a contralateral loss of pain and temperature sensation below the lesion. There is an
ipsilateral upper neurone lesion, with brisk reflexes, a Babinski sign, but no muscle wasting.
Loss of ipsilateral ankle jerk
The ankle jerk reflex would be preserved as it is mediated by the S1 segment of the spinal cord, which in this case is below the level of the injury.
Loss of pain in the ipsilateral foot
Due to damage to the lateral spinothalamic tract, there would be a contralateral, not ipsilateral loss of pain sensation in the foot. The contralateral foot is affected as the spinothalamic tract decussates at the level of the spinal cord.
Preservation of fine touch sensation in the ipsilateral foot
Fine touch sensation would be lost in a hemisection of the cord due to disruption to the posterior column of the spinal cord.
Wasting of the contralateral quadriceps muscle
Muscle wasting secondary to hemisection of the spinal cord does not occur as the lower motor neurones remain intact. Only if there were lower motor neurone lesions would muscle wasting be seen.
• • •
• MRCS Part A - Sep 2019 Exam
A patient presents as a trauma call with head and facial injuries. The radiologist calls you to say the patient has a fracture through the superior orbital fissure on CT scan.
Which one of the following nerves is most likely to be affected? Optic nerve
Mandibular division of the trigeminal nerve Maxillary division of the trigeminal nerve Trochlear nerve
Supra-orbital nerve
Explanation
Trochlear nerve
The oculomotor nerve (cranial nerve III), trochlear nerve (CN IV), ophthalmic nerve (CN Va), abducent nerve (CN VI) and sympathetic nerve fibres all pass through the superior orbital fissure. Therefore, the trochlear nerve is the correct answer here.
Optic nerve
The optic nerve leaves the orbit through the optic canal and would be unaffected by a superior orbital fissure fracture.
Mandibular division of the trigeminal nerve
The trigeminal nerve's closest anatomical relation to the superior orbital fissure is the ophthalmic nerve, but it would remain unaffected here.
Maxillary division of the trigeminal nerve
Again, the trigeminal nerve's closest anatomical relation to the superior orbital fissure is the ophthalmic nerve, but it would remain unaffected here.
Supra-orbital nerve
The supra-orbital nerve passes through the supra-orbital foramen and the orbital branches of the pterygopalatine ganglion pass through the inferior orbital fissure, so it would be
Which nerve has most likely been damaged? Dorsal scapular nerve
Long thoracic nerve Suprascapular nerve Musculocutaneous nerve Thoracodorsal nerve
Explanation
Long thoracic nerve
The long thoracic nerve arises from the roots of C5, C6 and C7. The nerve passes just posterior to the mid-axillary line deep to the fascia of serratus anterior and supplies this muscle in a segmental fashion. The serratus anterior muscle protracts the scapula in punching and pushing and keeps the vertebral border of the scapula in firm apposition with the chest wall. The nerve is potentially damaged by malpositioned chest drains. Dorsal scapular nerve
Damage to the dorsal scapular nerve is uncommon but would result in loss of power to the rhomboid muscles. These muscles help to pull the scapula towards the midline.
Suprascapular nerve
The suprascapular nerve supplies the supraspinatus and infraspinatus muscles and due to its anatomical course is unlikely to be damaged during chest drain insertion.
Musculocutaneous nerve
This nerve supplies the anterior compartment of the arm, and damage would not result in a winged scapula.
Thoracodorsal nerve
The thoracodorsal nerve supplies the latissimus dorsi muscle and is unlikely to be damaged during chest drain insertion. Damage to this nerve would not cause a winged scapula.
• MRCS Part A - Sep 2019 Exam
A 17-year-old man is brought to the Emergency Department following a road traffic collision, and is quickly diagnosed with hypovolaemic shock. Several attempts at
intravenous cannulation are unsuccessful, and so an incision is made anterior to the medial malleolus.
Which vessel should be cannulated? Anterior tibial veinDorsal venous arch Long saphenous vein
Medial marginal vein Short saphenous vein
Explanation
Long saphenous vein
The long (or ‘great’) saphenous vein passes anterior to the medial malleolus of the tibia before ascending up the medial aspect of the leg. It traverses the posterior aspect of the femoral medial epicondyle before ascending to penetrate the fascia lata and confluence with the femoral vein at the saphenofemoral junction. It can be accessed via an incision anterior to the medial malleolus when emergency venous access is required. Another option in this scenario would be to consider intraosseous (IO) access.
Anterior tibial vein
The anterior tibial veins are located deep in the lower leg, ascending in the intraosseous membrane so cannulation would not be possible from the incision described.
Dorsal venous arch
The dorsal venous arch is located on the dorsal aspect of the foot and would not be
accessible from the incision described in the question, it does however drain into the long saphenous vein.
Medial marginal vein
The medial marginal vein would not be accessible from an incision anterior to the medial malleolus as this vein is a continuation of the dorsal venous arch of the foot and the origin of the long saphenous vein.
A 45-year-old woman sustained a hip dislocation following a road traffic collision. She presents with reduced sensation on the dorsum of the foot and weakness of foot dorsiflexion.
Which nerve injury is responsible for this presentation?
The femoral nerveThe sciatic nerveThe superficial peroneal nerveThe sural nerveThe tibial nerve
Explanation
The sciatic nerve
Posterior hip dislocation is a common injury often occurring when the hip is flexed eg a road traffic collision. The two main complications are sciatic nerve damage and avascular necrosis. Sciatic nerve damage occurs because the sciatic nerve lies in close proximity to the posterior aspect of the joint capsule, damage to this nerve can cause reduced sensation on the dorsal of the foot and weakness of foot dorsiflexion. Avascular necrosis occurs due to tearing of the joint capsule, causing a disturbance of the blood supply to the femoral head.
The femoral nerve
The femoral nerve runs anterior to the hip joint, alongside the femoral artery and vein, it is therefore unlikely to be disrupted during a posterior dislocation of the femoral head. The superficial peroneal nerve
While superficial peroneal nerve damage could produce signs similar to those described in the case history, it would likely cause plantar flexion and as the nerve is located in the lower leg, it would not be affected by a posterior hip dislocation.
The sural nerve
Again, the sural nerve is located in the lower leg and would not be disrupted by a hip dislocation. It supplies sensation to the posterolateral aspect of the foot.
The tibial nerve
The tibial nerve is a branch of the sciatic nerve, however, it is located inferior to the hip joint and would not be affected by a dislocation.
• •
The decision to undertake limb amputation will be life changing for any patient. It should only be performed in particular circumstances.
In which one of the following situations is amputation of the lower limb considered absolutely necessary?
Absent plantar sensation
Muscle loss in two or more compartmentsSegmental bone loss greater than 1/3 tibial lengthUncontrollable haemorrhage from an open tibial injury
Warm ischaemia time exceeding 4–6 h
Explanation
Uncontrollable haemorrhage from an open tibial injury
A primary amputation is performed as a damage control procedure if there is
uncontrollable haemorrhage from an open tibial injury, usually occurring in multi-level arterial/venous damage in blast injuries.
Absent plantar sensation
Absent or reduced plantar sensation at time of presentation is not an indication for amputation, the tibial nerve and artery should be assessed intra-operatively. Muscle loss in two or more compartments
Muscle loss in two or more compartments present a relative indication for primary amputation, particularly when affecting the posterior compartment. Following limb salvage, further management with foot and ankle care, including orthotics may save the patient from a primary amputation.
Segmental bone loss greater than 1/3 tibial length
While significant segmental bone loss may require primary amputation of the limb it may not be absolutely necessary. Bone loss can be managed through several methods including; bone grafts, bone substitutes, free vascularised bone or bone regeneration through
distraction osteogenesis.
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• MRCS Part A - Sep 2019 Exam
A motorcyclist who had been involved in a high-speed accident was brought into a major trauma centre intubated and ventilated with full spinal protection. He was unconscious. After examination, he was noted to have priapism and did not respond to painful stimuli below the clavicle but did respond above the clavicle. The team leader suspected a cervical cord injury.
What is the most likely reason for this suspicion?
Given the mechanism of injury, and suspicion of a spinal cord injury, plain radiographs of the C-spine should be taken
Pre-hospital care teams can cause cervical cord injuries when removing the helmets of injured motorcyclistsThe patient had a blood pressure of 80/50 and a heart rate of 100 BPMThe patient had increased upper body toneThe patient had priapism and grimaced when given a painful stimulus above the clavicle but not below it
Explanation
The patient had priapism and grimaced when given a painful stimulus above the clavicle but not below it
Cervical cord injury is characterised by flaccid areflexia, diaphragmatic breathing and the ability to flex but not extend the elbow. Priapism is an uncommon but characteristic sign and is said to evolve from the abrupt loss of sympathetic input to the pelvic vasculature leads to increased parasympathetic input and uncontrolled arterial inflow directly into the penile sinusoidal spaces. In this case, the combination of priapism with loss of painful stimulus below the clavicle (ie dermatome level C5 and below) is more suggestive of cervical cord injury than the other options given.
Given the mechanism of injury, and suspicion of a spinal cord injury, plain radiographs of the C-spine should be taken
Clearly, the mechanism of injury is significant and the likelihood for multiple traumatic injuries is high. It would be more appropriate to undertake a full body trauma computed tomography (CT) scan, this will provide greater details regarding the cervical spine and cord than plan imaging. It will also allow investigation of other potential injuries.
shock with hypotension as a result of decreased systemic vascular resistance and
bradycardia because of unopposed vagal activity. Hypotension without bradycardia in the context of trauma must be assumed to be caused by haemorrhage until proven otherwise. The patient had increased upper body tone
Following cervical cord injury, one would expect reduced tone below the level of the injury and flaccid areflexia, not increased tone.
• • • • • • • •
A 50-year-old man was hit by a car, sustaining a proximal fibular fracture at the level of thefibular neck. Following the injury he had a foot drop gait, wasting and weakness of the anterior and lateral compartments of the calf but preservation of the posterior compartment muscles. There was loss of sensation over the dorsum of the foot including the 1st web space.
Which one nerve is the most likely to be damaged? Common peroneal nerveDeep peroneal nerve
Sciatic nerve
Superficial peroneal nerve Tibial nerve
Explanation
Common peroneal nerve
The common fibular nerve winds round the fibular neck. It supplies the lateral and anterior muscular compartments of the leg as well as the skin over the anterior aspects of the leg and dorsum of the foot. With foot drop, the patient trips on walking, as the toes catch the ground. Inversion is weakened because of paralysis of the tibialis anterior muscle. Muscle wasting is a sign of lower motor neurone damage. The peroneus longus tendon is one of the supports of the lateral arch; when this is paralysed, the arch is compromised.
Deep peroneal nerve
This nerve arises from the bifurcation of the common fibular nerve and is a deep structure whose course runs along the anterior surface of the interosseous membrane. As such, it is unlikely to be damaged by a fibular fracture.
Sciatic nerve
The sciatic nerve exits the pelvis through the greater sciatic foramen before bifurcating in the popliteal fossa to form the common fibular nerve and the tibial nerve. As such, the nerve is superior to the level of injury and unaffected.
Superficial peroneal nerve
This is a branch of the common fibular nerve and could be disrupted by a neck of fibular fracture, however, as sensation to the 1st web space is supplied by the deep peroneal nerve, the level of injury in the case history described must be higher.
Tibial nerve
The tibial nerve is a branch of the sciatic nerve and running deep within the posterior compartment of the lower leg, and would not be disrupted by a neck of fibular fracture.
Following a stab injury a patient has his sciatic nerve cut as it exits the pelvis. They have significant neurological deficits in the lower limb on that side.
Which one of the following statements is correct regarding this patient? Extension of the knee would be eliminated
The long head of the biceps femoris muscle would be affected but not the short head There would still be cutaneous sensation over the anteromedial surface of the thigh The muscles in the anterior compartment of the leg would still be functional
The sartorius and gracilis muscles would not be able to contract
Explanation
There would still be cutaneous sensation over the anteromedial surface of the thigh The sciatic nerve is a large nerve that runs down the lower limb. It is the longest single nerve in the body. The sciatic nerve supplies nearly the whole of the skin of the leg, the muscles of the back of the thigh and those of the leg and foot. A transection of the sciatic nerve at its exit from the pelvis will affect all the above-mentioned functions except cutaneous sensation over the anteromedial surface of the thigh, which comes from the femoral nerve.
Extension of the knee would be eliminated
Extension would be preserved as this movement is initiated primarily by the quadriceps muscles which are supplied by the femoral nerve.
The long head of the biceps femoris muscle would be affected but not the short head The long head is supplied by the tibial nerve and the short head by the common fibular nerve, both of which are branches of the sciatic nerve.
The muscles in the anterior compartment of the leg would still be functional
The muscles in the anterior compartment of the leg are supplied by the deep fibular nerve which is a distal branch of the sciatic nerve.
Sartorius and gracilis muscles are supplied by the femoral nerve and obturator nerve respectively therefore unaffected in a sciatic nerve injury.
• • • • • • • • • • • • • •
A 27-year-old man is brought into Accident and Emergency with closed facial fractures following a road traffic collision. They are otherwise fit and well.
Which one step is important in the initial management of facial injuries?
Antibiotics and tetanus immunisation are always requiredEarly surgical correction is preferableFacial X-rays are helpful and easy to interpretNasal intubation is always indicated
First aid and nasal cautery should be used initially to control any nasal bleeding
Explanation
First aid and nasal cautery should be used initially to control any nasal bleeding
When dealing with severe facial trauma, ATLS principles must be adhered to. Therefore in the initial management using the achievable benchmarks of care (ABCs) scenarios, bleeding must be sought and stopped, especially as this can lead to airway compromise.
Antibiotics and tetanus immunisation are always required
IV antibiotics may be necessary if there is the possibility of open fractures, but are not always necessary. Tetanus need only be given if the patient received their tetanus vaccination more than 10 years previously.
Early surgical correction is preferable
Surgery can usually wait until the patient is fully resuscitated. Facial X-rays are helpful and easy to interpret
Plain imaging can aide diagnosis and management of the injury, however, full assessment utilising the advanced trauma life support (ATLS) principles is the most important initial step in management of severe facial injuries. Additionally, and only when appropriate, chest X-ray must be performed as part of routine imaging, especially if the possibility of inhaled teeth is to be considered alongside facial imaging. Most patients will have a computed tomography (CT) traumagram soon after arrival.
Nasal intubation is always indicated
While this may be required in severe cases, endotracheal intubation (if required) can be achieved in many cases.
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• MRCS Part A - Sep 2019 Exam
A 24-year-old rugby player was injured during a match, and sustained a significant eye injury. Subsequently they presented to the Emergency Department and were diagnosed with an orbital floor fracture
Which one complication results from fractures of the orbital floor (‘blowout fractures’)?
Damage to the mental nerve leading to cheek numbnessDiplopia especially on upward gazeHyphemaOcular muscles ruptureRetinal detachment
Explanation
Diplopia especially on upward gaze
Blowout fractures occur along the orbital floor, as this is the thinnest part of the bone. Structures may herniate through into the ethmoidal or maxillary sinuses, causing the ‘trapdoor’ appearance on plain X-ray. Ocular injury occurs in 24% of cases, with
enophthalmos and diplopia the commonest signs. Computed tomography (CT) scan helps to delineate the fracture and aids in planning surgery if required.
Damage to the mental nerve leading to cheek numbness
Damage to the infraorbital nerve, not the mental nerve, leads to cheek numbness. Hyphema
A hyphaema is pooling of blood in the anterior chamber of the eye and can obscure vision. While it can be caused by ocular trauma, it is not as a result of an orbital floor fracture. Ocular muscles rupture
Again, while ocular muscle rupture may occur with trauma to the eye, it would not be as a result of an orbital floor fracture, more commonly diplopia occurs due to extra-ocular muscle entrapment.
Retinal detachment
Retinal detachment is more common with deceleration injuries and not blowout fractures.
• •
A 24-year-old man is rushed into the Emergency Department after being kicked in the neck during a karate competition. He has a hoarse voice and is very short of breath. On
examination, there is a marked stutter, laryngeal tenderness, subcutaneous emphysema and the patient is drooling saliva.
What is the first line treatment? Nasopharyngeal tube insertion CT angiogram of neck
Emergency tracheostomy
Endotracheal intubation with C-spine immobilisationSurgical cricothyroidotomy
Explanation
Endotracheal intubation with C-spine immobilisation
Fracture of the larynx can present with acute airway obstruction. The mechanism of injury usually involves either blunt or penetrating trauma to the larynx. Although the larynx is protected by the mandible above and the sternum below, it may be crushed, between these two points, by a blunt object anteriorly and the cervical spine posteriorly. It is diagnosed by the following triad: hoarseness of voice, subcutaneous emphysema and a palpable fracture. Other signs and symptoms include stridor, dysphagia, haemoptysis, laryngeal tenderness, odynophagia and anterior neck pain. Furthermore, there may be loss of thyroid cartilage prominence and ecchymosis in the overlying skin. If the patient’s airway is totally
obstructed or the patient is in severe respiratory distress, an attempt at endotracheal intubation is warranted (note that in trauma, C-spine immobilisation should be performed together with securing the airway). Flexible endoscopic-guided intubation may be helpful in this situation, but only if it can be performed promptly and by an experienced
anaesthetist or surgeon.
Nasopharyngeal tube insertion
The airway obstruction is due to a fractured larynx so insertion of nasopharyngeal tubes would be superior to the level of obstruction and unhelpful in this case.
CT angiogram of neck
This would not be the first line treatment: the airway must be secured before CT imaging. Computed tomography is the investigation of choice in suspected laryngeal trauma. It is especially useful in evaluating the extent of injury when flexible fibre optic examination is limited by laryngeal oedema.
Emergency tracheostomy
If intubation is unsuccessful and if surgical cricothyroidotomy cannot be performed, then an emergency tracheostomy is indicated. However, in emergency conditions, tracheostomy is difficult to perform, may be associated with profound bleeding and may be time
consuming.
Surgical cricothyroidotomy
Surgical cricothyroidotomy, although not preferred, may be a lifesaving option, progression should follow if endotracheal intubation is unsuccessful.
720 • • • • • • • • • • •
A 23-year-old man is brought into the Accident and Emergency Department as a trauma call after being stabbed in the neck by a rival gang member. The knife has been left in place and is entering through sternocleidomastoid on the left below the cricoid cartilage. His heart rate is 80 beats per minute and blood pressure 140/90. He is alert and able to speak in sentences.
What is your management plan? Barium swallow
Computed tomography (CT) angiogram of head and neck Endoscopy
Immediate transfer to theatre for exploration Remove knife in A&E and pack wound
Explanation
Computed tomography (CT) angiogram of head and neck
The patient in this question has sustained a penetrating neck injury to zone 1, and is
haemodynamically stable at present as judged by the observations given. It is not necessary to take the patient immediately to theatre, and imaging the affected area can assess the extent of damage and help plan the nature of intervention required. In zone 1 injuries as the thoracic inlet is involved, the thorax may need to be surgically explored, and therefore cardiothoracic surgeons maybe needed.
The zones of penetrating neck injury are:
• Zone 1 – Clavicle to cricoid cartilage
• Zone 2 – Cricoid cartilage to angle of mandible
• Zone 3 – Angle of mandible to base of skull. Barium swallow
A barium swallow is used to visualise the structures of the oesophagus, in this scenario, detailed imaging is required of the entire neck, not just the oesophagus. As such, this would not be appropriate. Additionally, the movements and positioning required for a barium swallow (ie extension of the neck) would risk the knife dislodging and damaging further structures to potential great harm.
Endoscopy
Endoscopy is used to visualise the oesophagus and stomach, clearly this is not the required imaging in this case.
Immediate transfer to theatre for exploration
As discussed, it is not necessary to take the patient immediately to theatre as they are currently stable, furthermore, imaging may help to plan the surgical intervention required. Remove knife in A&E and pack wound
Removal of the foreign body in this setting would be extremely risky and ill-advised. As the patient is currently stable, careful handing and CT imaging should take place while
planning for a surgical removal of the knife.
730 • • • • • • • • •
A 60-year-old man arrives into the Emergency Department’s Resuscitation Room with a suspected odontoid peg fracture following a fall at home. They are complaining of neck pain and have had their c-spine immobilised.
The odontoid peg is:
Connected to the axis by the alar ligamentPart of the atlas (C1 vertebrae)Seen on ‘open-mouth’ view X-raySuperior to the notochord remnantWeight bearing
Explanation
Seen on ‘open-mouth’ view X-ray
The odontoid peg can be visualised by plain film X-ray using the open-mouth view. This view is to primarily assess lateral mass alignment, not to assess for odontoid peg fracture. It is a notoriously difficult X-ray to interpret and if there are clinical concerns CT imaging should be sought.
Connected to the axis by the alar ligament
The alar ligaments together with the apical ligament are attached from the sloping upper edge of the odontoid peg to the margins of the foramen magnum. The alar ligaments limit rotation of the head and are very strong.
Part of the atlas (C1 vertebrae)
The odontoid peg forms part the axis which is the C2 vertebrae. Superior to the notochord remnant
The apical ligament is the fibrous remnant of the notochord and this lies superior to the odontoid peg.
Weight bearing
The axis (C2 vertebra) is characterised by the odontoid peg or dens that articulates with the atlas. It bears no weight.
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• • • •
• MRCS Part A - Sep 2019 Exam
A 23-year-old man is brought by friends into the Emergency Department after falling downstairs on leaving a nightclub. On examination, he is slightly drowsy, smelling of alcoholand complaining of neck pain.
What should be the immediate management of this patient? AnalgesiaC spine immobilisationImmediate head and neck CT IV access and fluid resuscitationIV Pabrinex
Explanation
C spine immobilisation
The fact a patient may be mobilising on admission to the Emergency Department should not distract from the nature of the injury and appropriate initial management. Given the mechanism of the injury and the complaint of neck pain, a traumatic injury to the C-spine is feasible and therefore this case should be dealt with using ATLS principles.
Analgesia
Pain relief is likely to be required, however, a full ATLS assessment given the history of significant trauma is required in the immediate management of this patient.
Immediate head and neck CT
Again, imaging may be required but immediate management must focus on an ATLS assessment.
IV access and fluid resuscitation
The history of trauma and complaints of neck pain necessitate a full ATLS assessment, and there is no indication of hypotension at present. Additionally, if the patient is
haemodynamically unstable, this would be identified during the initial assessment. IV Pabrinex
While there is a history of alcohol use in the case history, and IV Pabrinex may be indicated, the primary assessment should adhere to the ATLS principles and assessment of a potential neck injury.
A 26-year-old motorcyclist is involved in a high-speed collision. He reports pain over the left chest wall, and is short of breath. His pulse is 120/min, blood pressure 98/66
mmHg and respiratory rate 22/min. His jugular venous pressure is elevated. Heart sounds are muffled. Trachea is central with normal breath sounds. Chest X-ray reveals multiple left-sided rib fractures. The cardiac silhouette is enlarged.
Which one of the following is the most likely diagnosis in this patient?
Tension pneumothoraxRuptured thoracic aortaCardiac tamponadeFlail chestPericarditis
Explanation
Cardiac tamponade
Cardiac tamponade is usually caused by direct penetrating injury to the heart. It can also result from blunt injuries to the heart which causes injury to the pericardial vessels or high velocity injuries to the great vessels (eg, thoracic aorta) which results in pooling of blood in the pericardium. Apart from trauma, cardiac tamponade can result from carcinomas of the breast or lung, dissecting thoracic aneurysm, myocardial infarctions, and bacterial, viral or tuberculous pericarditis. Cardiac tamponade can be difficult to diagnose clinically,
especially in the Emergency Department. The classic (and diagnostic) signs of cardiac tamponade include a triad of (Beck’s triad) falling blood pressure, rising jugular venous pulse and muffled heart sounds. Pulsus paradoxus may also be an associated finding. The jugular venous pulse may paradoxically rise with inspiration (Kussmaul’s sign). Chest radiograph may reveal a globular heart, a convex or straight left heart border, and a right cardiophrenic angle of < 90°. Plain chest X-ray, echocardiogram (ECG), echocardiography and diagnostic pericardiocentesis are the commonly used investigations to diagnose cardiac tamponade.
Tension pneumothorax
A tension pneumothorax is an abnormal collection of air in the pleural cavity that leads to a significant impairment of respiration and circulation. A tension pneumothorax would be clearly visible on a chest radiograph (although it should be a clinical diagnosis), with a deviated trachea and reduced breath sounds on the affected side; all of which are not described in the case history.
Ruptured thoracic aorta
A ruptured thoracic aorta is likely to present with haemodynamic collapse which is not described in the case history. Furthermore, jugular venous pressure would be reduced due to haemorrhage and heart sounds would not be muffled.
Flail chest
A flail segment refers to two adjacent ribs fractured in two or more places resulting in a section of chest wall that moves independently and are often caused as a result of blunt
chest trauma. However, it would not cause muffled heart sounds, raised jugular venous pressure and falling blood pressure, all of which indicate cardiac tamponade.
Pericarditis
Pericarditis refers to inflammation of the pericardium which can present with a cardiac rub, however, it should not case muffled heart sounds or raised jugular venous pressure.
967 • • • • • • • • • • • •
A 58-year-old man is brought to hospital after being struck by a van at high speed. He is short of breath, blood pressure is 108/76 mmHg, pulse is 118/min, respiratory rate is 22/min and oxygen saturation is 88% on 100% oxygen. On examination of his chest, the trachea is deviated to the left, and the right lung is hyper-resonant to percuss with reduced air entry.
Which one of the following options is the most likely diagnosis in this patient? Pulmonary embolismTension pneumothoraxDiaphragmatic ruptureRuptured right main stem bronchusPulmonary contusion
Explanation
Tension pneumothorax
Blunt or penetrating trauma to the chest is the commonest cause for a tension pneumothorax. Other causes include barotrauma secondary to positive-pressure ventilation (especially when using high amounts of positive end-expiratory pressure), central venous catheter placement, chest compressions during cardiopulmonary
resuscitation, fibre-optic bronchoscopy with closed-lung biopsy and markedly displaced thoracic spine fractures. A tension pneumothorax results from any lung parenchymal or bronchial injury that acts as a one-way valve, allowing free air to move into an intact pleural space but prevents free exit of that air. The increased volume of air in the pleural space causes the lung on the affected side to collapse and eventually causes the
mediastinum to shift to the contralateral side. The shifted mediastinum impinges on, and compresses the contralateral lung, and also impairs venous return. The clinical signs and symptoms of this condition include sudden onset of severe chest pain, tightness of chest, breathing difficulty, distended neck veins, cyanosis, tachycardia and decreased mental alertness. The trachea and mediastinal structures are shifted to the contralateral side. The affected lung is hyper-resonant to percuss and there is usually reduced air entry on that side. Immediate management is through needle decompression of the chest, as a
temporising measure before insertion of a formal chest drain. Pulmonary embolism
The case history described is of significant chest trauma and not of a pulmonary embolism. A pulmonary embolism is most commonly seen following extensive surgical procedures, presenting with shortness of breath at rest, and reduced oxygen saturations. Hyper-resonance and reduced air entry would not be seen.
Diaphragmatic rupture
Diaphragmatic rupture causes herniation of the abdominal cavity into the thoracic cavity, and can be as a result of either blunt or penetrating trauma. On the affected side there would be reduced breath sounds, however it would also be associated with reduced resonance and mediastinal shift is unlikely.
Ruptured right main stem bronchus
This is a rare injury but can result from blunt or penetrating chest trauma, it is difficult to diagnose and treat. Subcutaneous emphysema is more commonly present in this type of injury than pneumothorax. Furthermore, if the pneumothorax does not resolve following insertion of a chest tube then this is indicative of a tracheal injury. Pneumomediastinum may also be present.
Pulmonary contusion
A pulmonary contusion can occur with chest trauma as the microvasculature is damaged, and while this patient is likely to have underlying pulmonary contusions, the primary diagnosis is of a tension pneumothorax given the hyper-resonance, mediastinal shift and reduced breath sounds.
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A 25-year-old footballer presents with pain in his leg after being kicked during a tackle. There is bruising over the posterior aspect of his leg, which is tense, swollen and tender. He reports altered sensation over the dorsum of his foot. Foot dorsiflexion and toe extension are painful and limited. He had normal posterior tibial and dorsalis pedis pulses on presentation, but they soon become difficult to palpate. Plain radiographs show no fractures.
Which one of the following options is the most appropriate cause for this patient’s signs and symptoms?
Deep venous thrombosis
Torn muscle bell ies of gastrocnem ius and soleus Compartment syndrome
Ruptured Achilles tendon
Thrombosis of the popliteal artery
Explanation
Compartment syndrome
Compartment syndrome is defined as an increase in the interstitial fluid pressure within an osteofascial compartment of sufficient magnitude to cause a compromise of the
microcirculation leading to necrosis of the affected nerve(s) and muscle(s). It is a well recognised and important complication of lower limb injuries, most commonly seen after fractures and crush injury, although it can occur in the absence of bony injury. The other causes for compartment syndrome include electrical injuries, deep thermal burns, venom from snake bites, restricting tourniquets, and fluid extravasation (eg intravenous regional anaesthesia). The patient may present with unremitting pain that is not relieved by high doses of opioid analgesics. Severe pain in response to passive stretch of the ischaemic muscles is by far the most dramatic and reliable clinical sign of compartment syndrome. Sensory loss occurs before motor loss. Early in its development, the peripheral pulses are normal, as is the colour and temperature of the affected part, as it is the microvasculature that is initially affected. Loss of peripheral pulses is usually a late and often sinister sign. With progression of the condition, the limb becomes tense and swollen, and if left
untreated, the muscle weakness progresses to paralysis. Untreated, irreversible myoneural necrosis occurs within 6–8 h. The areas of muscle may also infarct causing rhabdomyolysis, hyperkalaemia, hyperphosphataemia, high uric acid levels and metabolic acidosis.
Deep venous thrombosis
While a deep vein thrombosis (DVT) may present with a swollen, tender lower limb it would not be associated with the altered sensation and loss of pulses described in this case history.
Torn muscle bell ies of gastrocnem ius and soleus
The gastrocnemius and soleus are responsible for plantarflexion of the foot and flexion at the knee, neither of which movements are limited in the case history, therefore this is unlikely.
Ruptured Achilles tendon
A ruptured Achilles’ tendon would result in reduced plantar flexion, particularly passive plantar flexion when the knee is flexed, this is not described in the case history.
Additionally, the other signs and symptoms described would not be seen. Thrombosis of the popliteal artery
Thrombosis of the popliteal artery usually results from a popliteal artery aneurysm. It would present with an acutely ischaemic limb, and passive dorsiflexion would not be painful or limited. 1202 • • • • • •
A patient is admitted to the intensive care unit with a severe head injury following a road traffic collision. Vital observations are: heart rate 90, blood pressure 122/79, respiratory rate 7, SpO2 100 on 15 l O2 via non-rebreathe mask, Glasgow Coma Scale (GCS) 10. CT head
shows a large extradural haematoma.
What is the most likely acid–base disorder? Respiratory acidosis
Metabolic alkalosisRespiratory alkalosisMetabolic acidosis None of the above
Explanation
Respiratory acidosis
Respiratory acidosis occurs when the PaCO2 is raised and the pH lowered. It is caused by
hypoventilation. The causes can be divided into: airway obstruction, intrinsic lung disease, neuromuscular problems, chest wall problems and central respiratory-drive depression. This patient is hypoventilating (RR 7) due to the head injury.
Metabolic alkalosis
Trauma patients are at risk of metabolic acidosis due to hypovolaemia, not alkalosis. Respiratory alkalosis
Pulmonary embolus classically causes a respiratory alkalosis due to hyperventilation, although if respiratory depression and failure occurs in a patient with a massive pulmonary embolus, this would cause a respiratory acidosis.
Metabolic acidosis
Trauma patients are at risk of metabolic acidosis related to hypovolaemia, but there is no evidence to suggest that this patient has a depleted circulating volume (normal HR and BP). None of the above
Given the history of severe head trauma and subsequent CT imaging demonstrates a large extradural haematoma it is unlikely that this patient would not have an acid–base disorder.
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• MRCS Part A - Sep 2019 Exam
You respond to a trauma call. The patient has bilateral chest drains inserted and has lost 1000 ml of fresh blood into one and 750 ml of fresh blood into the other. The patient has a pulse rate of 80 bpm. Normal pulse rate 60–100 beats/min.
Which one of the following could all contribute towards suppressing the tachycardia response despite such significant haemorrhage?
Hyperthermia, a pacemaker, a-blockers and calcium antagonists Hyperthermia, a pacemaker, b-blockers and calcium antagonists Hypothermia, a pacemaker, a-blockers and calcium antagonists Hypothermia, a pacemaker, b-blockers and calcium antagonists Hypothermia, a pacemaker, b-blockers and dopamine antagonists
Explanation
Hypothermia, a pacemaker, b-blockers and calcium antagonists
Tachycardia in response to haemorrhage may be absent in: the elderly; patients on b-blockers and calcium antagonists; patients with hypothermia; and patients who have a pacemaker. Infants can develop a tachycardia and the rate will be much higher than in adults. Athletes have a higher cardiac output and stroke volume but a lower resting pulse than the average population. The usual responses to hypovolaemia may not be manifest in athletes until a significant blood loss has occurred.
Hyperthermia, a pacemaker, a-blockers and calcium antagonists
Hyperthermia and a-blockers would not contribute to suppressing the tachycardia response to significant hypovolaemia.
Hyperthermia, a pacemaker, b-blockers and calcium antagonists
Dopamine antagonists do not affect the response to significant haemorrhage. • • • • • • • • • • • • • • • •
• MRCS Part A - Sep 2019 Exam
A 27-year-old man is rushed to the Emergency Department after being stabbed in the neck. He is bleeding very heavily and there is concern he is haemodynamically compromised due to the bleeding and the massive haemorrhage protocol is therefore activated.
Which one of the following combinations most accurately describes the physiological response to a loss of circulating blood volume?
Increased peripheral venular vasoconstriction, increased peripheral arteriolar vasoconstriction, increased resistance to blood flow, haemodilution, bradycardia Reduced peripheral venular vasoconstriction, reduced peripheral arteriolar vasoconstriction, reduced resistance to blood flow, haemodilution, bradycardia Increased peripheral venular vasoconstriction, increased peripheral arteriolar vasoconstriction, increased resistance to blood flow, haemodilution, tachycardia Reduced peripheral venular vasoconstriction, reduced peripheral arteriolar
vasoconstriction, increased resistance to blood flow, haemoconcentration, bradycardia Increased peripheral venular vasoconstriction, reduced peripheral arteriolar
vasoconstriction, increased resistance to blood flow, haemodilution, bradycardia.
Explanation
Increased peripheral venular vasoconstriction, increased peripheral arteriolar vasoconstriction, increased resistance to blood flow, haemodilution, tachycardia Vasoconstriction is widespread and occurs on both the venous and arterial sides of the circulation. The result is increased peripheral resistance to blood flow. Changes in vascular pressures lead to an influx of extra-cellular water into the circulation, a phenomenon known as ‘transcapillary refilling’. This leads to haemodilution. Tachycardia occurs as the blood pressure falls, which is sensed by baroreceptors in the carotid arteries and aortic arch.
Increased peripheral venular vasoconstriction, increased peripheral arteriolar vasoconstriction, increased resistance to blood flow, haemodilution, bradycardia Vasoconstriction, increased resistance to blood flow and haemodilution would be seen, however, bradycardia would not be seen, as one of the most immediate responses to loss of
Reduced peripheral venular vasoconstriction, reduced peripheral arteriolar
vasoconstriction, increased resistance to blood flow, haemoconcentration, bradycardia Changes in vascular pressures lead to an influx of extra-cellular water into the circulation, a phenomenon known as ‘transcapillary refilling’. This leads to haemodilution, not
haemoconcentration.
Increased peripheral venular vasoconstriction, reduced peripheral arteriolar vasoconstriction, increased resistance to blood flow, haemodilution, bradycardia. Vasoconstriction is widespread and occurs on both the venous and arterial sides of the circulation. While tachycardia, not bradycardia, is one of the most immediate responses to a loss of circulating volume.
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• MRCS Part A - Sep 2019 Exam
You attend a trauma call to a 40-year-old patient who has been involved in a road traffic accident. In the Resuscitation Room who has sustained a significant isolated closed head injury and has a Glasgow Coma Score (GCS) of 7.
Which one is the most appropriate way to definitively manage the patients airway? CricothyroidotomyNasopharyngeal tubeOropharyngeal tubeOrotracheal
intubationTracheostomy
Explanation
Orotracheal intubation
A definitive airway requires a tube present in the trachea with the cuff inflated (although uncuffed for prepubertal children), the tube connected to a form of oxygen-enriched assisted ventilation and the airway secured in place with tape. The decision to provide a definitive airway is based on clinical findings including:
• presence of apnoea
• inability to maintain a patent airway by other means
• need to protect the lower airway from aspiration of blood, vomitus or other foreign bodies
• impending or potential compromise of the airway, eg, following inhalation injury or facial fractures
• major facial burns
• compression from neck haematoma, eg, retropharyngeal haematoma
• upper airway, pharyngeal or facial haemorrhage
• presence of a closed head injury requiring assisted ventilation in patients with a GCS score <8
• sustained seizure activity
with orotracheal intubation is preferred by most anaesthetists as the primary method of securing a definitive airway.
Oropharyngeal tube
Oropharyngeal or nasopharyngeal tubes (airways) are not forms of definitive airways. Tracheostomy
There are not features in this case that suggest the need for a surgical airway over an orotracheal tube. 1881 • • • • • • • • • • •
• MRCS Part A - Sep 2019 Exam
A 25-year-old man is admitted to the Emergency Department with severe polytraumatic injuries following a road traffic collision. He is managed as per ATLS guidelines and undergoes damage control surgery.
Which one of the following physiological responses would you expect to find within the first few hours of his injury?
Decreased glucose levelsDecreased lactate levelsIncreased body temperature Increased catecholamine levelsIncreased oxygen consumption
Explanation
Increased catecholamine levels
In the first few hours of a traumatic injury to the body, a complex series of responses are set in motion. This is known as the ebb phase, the features of which include decreased body temperature, decreased oxygen consumption, lactic acidosis, increased stress hormone levels, decreased insulin levels, hyperglycaemia and insulin resistance, increased substrate consumption, immune activation and a hepatic acute-phase response. The following days to weeks represents the ‘flow phase’, which features increased body temperature, increased oxygen consumption, negative nitrogen balance, increased stress hormone levels,
hyperglycaemia, gluconeogenesis, proteinolysis, lipolysis and immunosuppression. Decreased glucose levels
Hyperglycaemia is a common post traumatic injury, in the following days to weeks as the body enters the flow stage blood glucose levels will normalise.
Decreased lactate levels
A lactic acidosis from increased lactate levels is common following trauma. Increased body temperature
Body temperature initially reduces in the first few hours following traumatic injury. Increased oxygen consumption
A 25-year-old man is admitted to the Emergency Department with severe polytraumatic injuries following a road traffic collision. CT scan demonstrates a ruptured spleen and the decision is made to take him to theatre.
Which one of the following physiological responses would you expect to find? Glycogenesis
Increased insulin secretionReduced blood glucose levelsReduced excretion of excess water in the first 48 hours
Sodium excretion in first 48 h
Explanation
Reduced excretion of excess water in the first 48 hours
Antidiuretic hormone (ADH), catecholamines and corticosteroids are elevated following trauma. This has the effect of conserving sodium and water and producing a
hyperglycaemia. Glycogenesis
Glycogen stores are broken down, not formed during the initial response to traumatic injury.
Increased insulin secretion
Reduced insulin secretion is seen in the response to trauma, coupled with increased secretion of catecholamines and corticosteroids, this produces a hyperglycaemia. Reduced blood glucose levels
Blood glucose levels will increase due to the reduction in insulin secretion and increase in catecholamines and corticosteroids.
Sodium excretion in first 48 h
As discussed, the physiological response to trauma involves secretion of antidiuretic hormone which reduces sodium excretion in the first 48 h.
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• MRCS Part A - Sep 2019 Exam
A young man is admitted to the Emergency Department’s Resuscitation room
in hypovolaemic shock following a stab injury to his abdomen. He is pale and it is clear he has lost a significant amount of blood.
Which one of the following changes in cellular metabolism would you expect to in these circumstances?
Increased adenosine triphosphate (ATP) production Passage of potassium into cells
Excretion of sodium out of cells Reduced ketone production Accumulation of lactic acid
Explanation
Accumulation of lactic acid
Changes in cellular metabolism associated with shock include accumulation of lactic acid and reduced ATP production due to anaerobic metabolism as a result of reduced oxygen carrying capacity of the circulating volume.
Increased adenosine triphosphate (ATP) production
There is reduced ATP production due to anaerobic respiration which has a lower yield of ATP when compared with aerobic respiration.
Passage of potassium into cells
Changes in membrane function result in the passage of sodium into cells and the passage of potassium out of cells.
Excretion of sodium out of cells
As discussed, changes in membrane function result in the passage of sodium into cells. Reduced ketone production
A 77-year-old woman develops central chest pain two days following surgery for a fractured neck of femur. Her temperature is 37.7°C, heart rate 110 beats per min and respiratory rate 28 breaths per min. Other results are below:
Result Normal range White blood cell count 9 × 109/l 4–11 × 109/l
Oxygen saturation 99% on room air 94–98% on room air What is the most probable diagnosis?
Pulmonary embolism Sepsis
Musculoskeletal chest pain
SIRS secondary to myocardial infarction Aspiration pneumonia
Explanation
SIRS secondary to myocardial infarction
The four criteria for systemic inflammatory response syndrome (SIRS) are:
• temperature <36°C or >38°C
• HR >90 beats per min
• RR >20 breaths per min or p(CO2) <4.3 kPa
• white cell count <4 or >12 × 109/l.
At least two of the criteria need to be met for a patient to exhibit SIRS. Immunosuppressed patients, the elderly and patients taking steroids are less likely to mount a normal
physiological response. SIRS may be exhibited in septic patients but may occur in response to other physiological stresses, including myocardial infarction and pulmonary embolism.
These conditions can result in a low-grade pyrexia. It is early for this woman to develop sepsis and her main complaint is chest pain. She has SIRS (raised HR and RR) and this is more likely to be due to cardiac ischaemia in an elderly patient who has undergone major surgery.
Pulmonary embolism
The risk of pulmonary embolism (PE) following major surgery is increased and venous thromboprophylaxis is given post-surgery. A pulmonary embolism may present with pleuritic chest pain, reduced oxygen saturation, tachypnoea, and tachycardia. While the patient has some of these features, and PE is a differential diagnosis, a myocardial infarction should be excluded first.
Sepsis
There is no mention of a source of infection in the scenario, making sepsis unlikely. Musculoskeletal chest pain
While it is possible that the pain could be musculoskeletal, given her recent major surgery, elderly age and physiological parameters, this woman warrants investigation for a
myocardial infarction. Aspiration pneumonia
Aspiration can be a complication either of intubation before surgery, or altered Glasgow Coma Scale (GCS) score. However, the case history does not describe any issues with
intubation and furthermore, her oxygen saturations are entirely satisfactory. Another cause for this presentation should be sought.
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A 55-year-old man sustains a femoral shaft fracture in a road traffic collision. He arrives in the Emergency Department with a heart rate of 130 beats per minute (bpm) and blood pressure of 70/40 mmHg.
If he is given a 500 ml intravenous bolus of 0.9% saline, what is most probable outcome?
This patient’s central venous pressure (CVP) would be around 10 cmH2O before the bolus
There will probably be an initial rise and then fall in central venous pressure (CVP) This will produce the same intravascular expansion as 2 litres of 0.9% saline This will produce a sustained CVP rise of more than 4 cmH2O
5% dextrose would produce a similar increase in intravascular volume
Explanation
There will probably be an initial rise and then fall in central venous pressure (CVP) The clinical picture is one of hypovolaemic shock in the context of trauma. You would therefore expect this patient’s CVP to rise with the fluid challenge, but then drop back to its original value if either the patient is not fully resuscitated, or has ongoing bleeding. The choice of fluid for use in resuscitation can be complex with much debate around the choice between crystalloid and colloid, however, recent NICE guidelines suggest use of
intravenous crystalloid as the primary resuscitation fluid with synthetic colloids largely falling out of favour. Evidence has shown increased risk of renal impairment, allergic reactions and accumulation with organ damage.
This patient’s central venous pressure (CVP) would be around 10 cmH2O before the bolus
The normal CVP range is 3–8 cmH2O. A low or negative reading confirms a low circulating
blood volume.
This will produce the same intravascular expansion as 2 litres of 0.9% saline
One litre of 0.9% saline would produce the same intravascular expansion as 200 ml of Gelofusine, however, in clinical practice, synthetic colloids are now rarely used due to complications such as anaphylactic reactions. Recent evidence suggests an increased mortality when colloids are used in resuscitation of critically injured patients.
This will produce a sustained CVP rise of more than 4 cmH2O
The response of the CVP to a fluid challenge gives much information regarding the state of the circulation. A dehydrated patient’s CVP will rise in response to a challenge but fall if they remain underfilled. A sustained rise indicates a well filled patient, but an elevation of greater than 4 cmH2O indicates overfilling or a failing myocardium.
5% dextrose would produce a similar increase in intravascular volume
5% dextrose should not be used for resuscitation as it distributes evenly across all compartments and will result in only a limited increase in intravascular volume.
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• MRCS Part A - Sep 2019 Exam
A 33-year-old woman is brought into the Emergency Department with severe burns. She requires intubation and is admitted to the Intensive Care Unit. Her potassium is 6.0 mmol/l (normal value 3.5–5.0 mmol/l).
In these circumstances, to what is her hyperkalaemia most probably due? Dopamine infusion
Metabolic alkalosis
Suxamethonium chloride, administered during rapid sequence induction Burns
Septic shock
Explanation
Burns
Due to the massive tissue destruction associated with severe burns, hyperkalaemia ensues due to cell lysis and release of previously intracellular potassium into the extracellular space, and subsequently causing a plasma rise in potassium.
Dopamine infusion
Catecholamines, such as adrenaline and dopamine, stimulate the sodium/potassium pump causing a shift of potassium into cells, thus plasma concentration of potassium would probably fall.
Metabolic alkalosis
Acidosis, rather than alkalosis (eg severe renal failure, ketoacidosis, lactic acidosis) can cause an altered distribution of potassium and possible hyperkalaemia. Given the history, severe burns are the more probable cause of this woman’s high potassium levels.
Suxamethonium chloride, administered during rapid sequence induction
Suxamethonium chloride is a depolarising muscle relaxant, mimicking acetylcholine at the neuromuscular junction and frequently used in trauma/burns patients requiring rapid sequence induction and endotracheal intubation. It produces only a transient rise in plasma
potassium (and creatinine phosphokinase) concentrations, and her burns are the more likely source.
Septic shock
Although septic shock would cause acidosis and hyperkalaemia, it is too early for its onset.
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You are treating a 30-year-old man with a fracture dislocation of the ankle, the capillary refill in the foot is 2 s and the pulse is weak, but palpable. You need to reduce the
dislocation using sedation in the resuscitation room.
Which one of the following options is appropriate regarding sedation for this procedure?
Diazepam is preferred to midazolam when given intravenously Sedation can ideally be given when the patient has eaten 1 h before
Sedation is optimal when the patient loses response to verbal commands or physical stimulus
The airway should be monitored closely by the person performing the reduction Ketamine is a useful sedative drug as the patient retains protective airway reflexes, spontaneous respiration and cardiopulmonary stability
Explanation
Ketamine is a useful sedative drug as the patient retains protective airway reflexes, spontaneous respiration and cardiopulmonary stability
Ketamine can be used for dissociative sedation which produces a cataleptic state
characterised by profound analgesia and amnesia. Of benefit is the retention of protective airway reflexes, spontaneous respiration and cardiopulmonary stability. It is safe for use in short procedures and in less monitored areas (when compared to operating theatres) such as resuscitation rooms.
Diazepam is preferred to midazolam when given intravenously
A short-acting benzodiazepine such as midazolam is easier to control and reverse than a longer-acting one such as diazepam, and thus is preferred.
Sedation can ideally be given when the patient has eaten 1 h before
Sedation can lead to similar aspiration risks as anaesthesia and so fasting is important. Sedation is optimal when the patient loses response to verbal commands or physical stimulus
If a patient becomes unarousable, as described here, they are said to be anaesthetised with all the risks that this carries.
The airway should be monitored closely by the person performing the reduction
The practitioner performing the procedure is not able to devote the attention to monitoring sedation safely and a dedicated individual should be appointed to do so.
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A patient is involved in an RTA, they have had severe trauma to right lower limb. Imaging demonstrates a displaced and comminuted mid-shaft femoral fracture.
The acute phase response seen following a lower limb injury can include which one of the following options?
Increased insulin levelsIncreased liver glycogen levelsIncreased plasma catecholaminesReduced plasma fatty acidsRelative hypoglycaemia
Explanation
Increased plasma catecholamines
During the acute phase of injury, the body enters a catabolic phase in which increased levels of catecholamines cause glycogen to be broken down in the liver and muscle to provide glucose.
Increased insulin levels
Insulin levels fall and the glucose levels rise in the catabolic phase. Increased liver glycogen levels
As discussed, during the catabolic phase glycogen is broken down in the liver to release glucose.
Reduced plasma fatty acids
Increased sympathetic activity also causes mobilisation of fat from adipose tissue. Relative hypoglycaemia
Glucose levels rise during the catabolic phase due to break down of stores of glycogen.
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• MRCS Part A - Sep 2019 Exam
A patient is recovering from an emergency laparotomy in HDU. They have had adhesiolysis for small bowel obstruction, no resection was required.
Which one of the following metabolic changes occurs in the ebb phase (first 24 h) of response to injury?
Plasma pH increases
The plasma level of free fatty acids increases Hypoglycemia
The plasma level of non-protein nitrogen decreases Plasma cortisol increases
Explanation
Plasma cortisol increases
There is an immediate rise in serum cortisol post surgery. Plasma pH increases
There is usually acidosis, meaning plasma pH decreases not increases, during the ebb phase response following injury. The acidosis seen is primarily driven by the increased production of lactic acid in a response to anaerobic respiration.
The plasma level of free fatty acids increases
Lipolysis increases during the flow phase leading to increase in fatty acids and glycerol in the flow phase.
Hypoglycemia
Due to the catabolic state seen in the ebb phase, there will be increase in plasma glucose, ie hyperglycaemia due to glycogenolysis.
A 30-year-old man is admitted, having fallen 6 metres, sustaining a significant head injury. They appear confused on initial assessment and this does not subsequently improve. When managing their intracranial pressure and cerebral blood flow following head injury, which one of the following statements is correct?
Cerebral blood flow rises in direct proportion to increases in systolic blood pressure Hyperventilation increases cerebral blood flow
Reduced p(CO2) reduces intracranial pressure
Intracranial pressure can be reduced by controlled hypoventilation
Raised blood pressure and tachycardia are signs of elevated intracranial pressure
Explanation
Reduced p(CO2) reduces intracranial pressure
Hyperventilation reduces the carbon dioxide tension in the blood; this leads to cerebral vasoconstriction thereby reducing cerebral blood flow and hence reduces intracranial pressure.
Cerebral blood flow rises in direct proportion to increases in systolic blood pressure It is important to note that cerebral perfusion pressure (CPP) = mean arterial pressure (MAP) – intracranial pressure (ICP) or central venous pressure (CVP, whichever is higher). As such, cerebral blood flow correlates more strongly with MAP, not systolic blood
pressure.
Hyperventilation increases cerebral blood flow
Hyperventilation will decrease cerebral blood flow due to vasoconstriction triggered by a low p(CO2).
Intracranial pressure can be reduced by controlled hypoventilation
Hypoventilation will cause a relative rise in p(CO2), which will trigger vasodilation
increasing the cerebral blood flow and subsequently the intracranial pressure. Raised blood pressure and tachycardia are signs of elevated intracranial pressure
Cushing’s reflex, raised blood pressure and bradycardia (not tachycardia) is a consequence of raised intracranial pressure.
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