El-Boghdadly - 10 Flashcards
- A 36-year-old man requires trans-sphenoidal surgery for a large anterior pituitary
tumour with suprasellar extension.
Prior to induction, which of the following are you most likely to need to prepare?
A Fibreoptic scope
B Lumbar drain
C Invasive arterial blood pressure monitoring
D Intravenous insulin administration
E Postoperative ventilation
A
- C Invasive arterial blood pressure monitoring
The majority of pituitary tumours are approached surgically by the trans-sphenoidal
route. This involves passage through the sphenoid sinus and removal of the floor
of the pituitary fossa (sella turcica). The fossa is defined laterally by the cavernous
sinus and superiorly by the sella diaphragma. It is important to remain aware that
the cavernous sinus contains portions of the carotid arteries – a cause of significant
and rapid blood loss in the event of surgical trauma. For this reason, in addition to
the potential requirement of careful blood pressure manipulation, invasive arterial
pressure monitoring is essential for all trans-sphenoidal pituitary surgery.
The most common pituitary tumours arise from the anterior lobe and are usually
adenomas, 75% of which are hormone secreting. Hyper-or hyposecretion of growth
hormone (GH), adrenocorticotrophic hormone (ACTH), prolactin (PRL) and thyroidstimulating
hormone (TSH) can occur depending on the cell-origin or mass effect of
the tumour. If an adenoma is present that leads to GH or ACTH secretion, the patient
may develop acromegaly or Cushing’s disease respectively. In either case, this may
lead to glucose intolerance or frank diabetes requiring insulin.
Acromegalic patients often present with soft tissue changes particularly of the
larynx and oropharynx. This leads to thickened mucosa, affecting visualisation of
the airway, and glottic stenosis. They may also have an enlarged mandible and
maxilla resulting in poor occlusion of the dental aperture. This renders them at
risk of a difficult airway which can be graded from 1–4. Grade 1 is classified as
minimal mucosal involvement, grade 2 as mucosal hypertrophy in the region of
the naso pharynx and oropharynx, grade 3 as isolated glottic changes and grade 4
as comprising of elements from both 2 and 3. It is recommended that a fibreoptic
intubation is considered for grades 1–2 and a surgical tracheostomy for grades 3–4.
Many patients who suffer Cushingoid or acromegalic effects from their tumour
acquire obstructive sleep apnoea. This obligates consideration of safe postoperative
airway management and possible ventilation strategies as any positive pressure
ventilation applied nasally is prohibited in the immediate period following transsphenoidal
surgery.
- A 20-year-old male trauma patient has arrived in the emergency department
was had flaccid paralysis of both lower limbs before being intubated at scene for
transfer. A full body CT scan revealed a complex vertebral fracture of T5 with a
retropulsed fragment and an undisplaced sacral fracture. Despite 2 litres of fluid
resuscitation his blood pressure remains 80/40 mmHg with a heart rate of 69 beats
per minute.
Which of the following is the most likely reason for his fluid resistant hypotension?
A Spinal shock
B Tension pneumothorax
C Haemorrhage
D Pulmonary embolus
E Neurogenic shoc
E
- E Neurogenic shock
A tension pneumothorax should always be considered in a patient who is
undergoing positive pressure ventilation after intubation. As a result of increasing
pressure within the pleural cavity, the lung collapses and ultimately the
mediastinum shifts. This leads to obstructed venous return and therefore persistent
hypotension until the pressure is released by needle decompression or chest drain
insertion. Hypotension is therefore a relatively late sign and considering the recent
CT scan did not show an existing pneumothorax this is not the most likely reason.
All trauma patients with hypotension should be treated with ongoing suspicion
of haemorrhage. Most sources of significant blood loss, without obvious external
injury, should be identified by a CT scan using contrast media. Even though this
patient has had negative imaging, a sacral fracture can lead to the development of a
retroperitoneal haematoma. The fracture is, however, undisplaced and although this
is not currently the most likely reason it is still one to bear in mind.
Pulmonary embolism is defined as the obstruction of a pulmonary artery or arteriole
by intravascular matter such as air, thrombus or fat. If large, it may lead to prevention
of flow to the left heart, failure of the right heart and subsequent circulatory
collapse. Pulmonary emboli in trauma patients mainly occur as fat (classically
secondary to long bone fractures) or thrombus (more often after significant periods
of lower limb immobilisation). Although this should be considered it is less likely
within the time frame, or associated with the injuries described.
Neurogenic shock occurs when the autonomic pathways are interrupted as in a
spinal cord injury. It leads to hypotension and bradycardia. High thoracic injuries are
particularly associated with these signs as the cardiac sympathetic fibres originate
from T2-T5 thereby resulting in reduced inotropy, unchallenged vagal tone and
decreased systemic vascular resistance. This is the most likely reason in this example.
Spinal shock is described as the absence of reflexes below the level of injury. This
would produce the flaccid areflexia noted in this case and although normally seen
with hypotension from neurogenic shock, does not best define the reason for the
patients fluid resistant hypotension.
- You are asked to anaesthetise a 68-year-old man for rigid bronchoscopy for biopsy
of a posterior tracheal mass. He has normal mouth opening and neck extension.
Which of the following is the most appropriate anaesthetic technique?
A Spontaneous ventilation with lidocaine topicalisation of the airway and
sedation with intravenous midazolam
B Inhalational induction and maintenance of deep anaesthesia with sevoflurane
and oxygen via a facemask removed when the bronchoscope is inserted
C Intravenous induction with propofol and atracurium. Oxygen and sevoflurane
maintenance with intermittent positive pressure ventilation (IPPV) via a
microlaryngeal tube
D Intravenous induction with propofol and atracurium followed by low frequency jet ventilation via the bronchoscope. Maintenance of anaesthesia with propofol and remifentanil target controlled infusion (TCI)
E Placement of cricothyroid cannula followed by anaesthesia with propofol and
remifentanil TCI. Jet ventilation via the cricothyroid cannula
B
3 D Intravenous induction with propofol and atracurium
followed by low frequency jet ventilation via the
bronchoscope. Maintenance of anaesthesia with propofol
and remifentanil TCI
Anaesthesia for airway surgery raises a number of issues including:
• Shared airway with conflicting needs of the surgeon (clear, unobstructed views
of the operative field) and anaesthetist (airway protection and maintenance of
oxygenation, ventilation and anaesthesia)
• Co-morbidities of the patient group who may have malignant, respiratory and
cardiovascular disease
The rigid bronchoscope is a large instrument and it is highly unlikely that a patient
would be able to tolerate the procedure without general anaesthesia. Although
inhalational induction may be a valid technique, deep anaesthesia alone may
not be sufficient (without paralysis) and the use of intermittently removing the
facemask will increase the risk of awareness as well as hypoxaemia. Use of a
microlaryngeal tube may be acceptable for certain procedures (e.g. supraglottic)
but a microlaryngeal tube may occlude the posterior trachea and when inflated the
cuff will mean any lesions in all but the most proximal part of the trachea would be
inaccessible. These are therefore unfeasible options in this case.
Low frequency jet ventilation is delivered via a handheld trigger device (e.g.
Manujet) attached via a Luer lock connector to the rigid bronchoscope. The operator
can manually deliver oxygen under pressure at a rate of 10–20 breaths per minute.
Volatile anaesthetic agents cannot be delivered via the rigid bronchoscope so total
intravenous anaesthesia (TIVA) is required. Intravenous induction with propofol
and atracurium with low frequency bronchoscopic jet ventilation and TIVA provides
good surgical conditions as well as anaesthesia and is best response given here. It
should be noted that there is a risk of barotrauma and gas trapping when using jet
ventilation and it is not possible to accurately monitor end tidal carbon dioxide or
airway pressures.
High frequency jet ventilation can be delivered via a cricothyroid cannula which may
be left in place for emergency perioperative oxygenation in patients felt to be ‘at
risk’; for example those will difficult laryngoscopy. This would therefore not be the
first choice technique in this case based on the information given.
As these patients are at risk of complete airway obstruction or complications
including bleeding, airway oedema, laryngospasm and barotrauma/
pneumothoraces it is prudent to be familiar with the difficult airway trolley and have
equipment and personnel available to deal with any complications.
- A 33-year-old man is extracted from a house fire and admitted to the emergency
department. He cannot remember being rescued and on examination has
singed nasal hair, burns across his neck and productive carbonaceous sputum.
He is receiving high flow oxygen through a non-rebreathing mask and is not in
respiratory distress.
Which investigation will be most useful in assessing and managing his upper airway?
A Pulse oximetry
B Chest X-ray
C Computed tomography
D Arterial blood gas
E Flexible bronchoscopy
- E Flexible bronchoscopy
Smoke inhalation injury is a serious complication of burns and significantly increases
patient morbidity and mortality. Airway injuries in this context can be difficult to
safely manage and requires an appreciation of the risk factors, natural progression
and appropriate investigations available.
During a fire, the upper airway may be injured from chemical irritation and direct
thermal insult resulting in oedema, erythema and ulceration, which can threaten
airway patency. Other factors detrimental to the airway include the systemic
inflammatory response, aggressive fluid administration and accompanying neck
burns causing external compression. The airway oedema is variable but generally
peaks at 24 hours and clinical symptoms such as stridor or dyspnoea may not be
Patients who have lost consciousness and been exposed to heat or flames in an
enclosed space for a prolonged time are at higher risk of airway injury. Physical signs
suggestive of airway injury include facial burns, singed nasal hairs, carbonaceous
sputum, stridor, hoarseness and drooling. Certain investigations can also guide
assessment and management of inhalational airway injuries
Flexible bronchoscopy is considered the gold standard for early evaluation of
the upper airway in patients with smoke inhalational injuries and it is the correct
answer for the above scenario. Bronchoscopy allows direct visualisation of the
laryngeal structures and an appreciation of any oedema, ulceration, necrosis or
soot contaminating and threatening the airway. Furthermore, bronchoscopy
allows removal of any airway debris, and the placement of an endotracheal tube if
indicated. Repeat examinations can also be performed to assess the progression of
airway injury.
- A previously well 9-year-old boy is having a laparoscopic appendicectomy.
Anaesthesia was induced uneventfully with thiopentone and suxamethonium,
followed by a sevoflurane/oxygen mix. 10 minutes after port insertion his airway
pressures increase and his oxygen saturations begin to fall. Despite adjusted
mechanical ventilation, his end-tidal CO₂ reaches 9.0 kPa. His heart rate rises to
180 beats per minute and his temperature to 40°C.
Which of the following actions will ameliorate the situation most definitively?
A Hyperventilation with 100% oxygen
B Cooling the patient
C Switching maintenance of anaesthesia to propofol
D Treating any hyperkalaemia
E Dantrolene 1–10 mg/kg
C
- E Dantrolene 1–10 mg/kg
In the event of an unexplained significant rise in end-tidal CO₂ and heart rate
with simultaneous increased oxygen requirements, the possibility of malignant
hyperthermia must not be overlooked.
Malignant hyperthermia is a genetically determined error of skeletal muscle
metabolism that is triggered by suxamethonium and volatile anaesthetic agents.
It is thought to arise from a defective gene for the ryanodine/dihydropyridine
receptor on chromosome 19. This leads to an uncontrolled inward flux of calcium
ions and subsequent rapid development of skeletal muscle rigidity. This generates
a hypermetabolic state producing dramatic rises in CO₂, O₂ consumption and
temperature. As the condition persists, haemodynamic instability, rhabdomyolysis,
hyperkalaemia, metabolic acidosis and disseminated intravascular coagulation develop.
The mainstays of initial treatment are to rapidly acquire dantrolene at the earliest
point of suspicion, whilst simultaneously minimising the deleterious effects of
the process. These include informing the team of your diagnosis, calling for help,
hyperventilating the patient on 100% oxygen, removing volatile anaesthesia from
the circuit, maintaining anaesthesia via intravenous agents, cooling the patient and
treating any biochemical abnormalities.
Dantrolene is the only known antidote to malignant hyperthermia and is therefore
the most definitive treatment. The Association of Anaesthetists of Great Britain
and Ireland (AAGBI) guidelines on the recommended stages of management are
available on the AABGI website
- A 53-year-old man presents for a laparoscopic gastric bypass procedure. He has
a BMI of 46 kg/m2 and is an ex-smoker. He has a diagnosis of obstructive sleep
apnoea, but doesn’t really use his CPAP machine. He has severe reflux and a neck
circumference of 46 cm, his Mallampati score is 1 and he has good mouth opening.
The most appropriate anaesthetic plan includes:
A Ramped head-up position, preoxygenation, and a rapid sequence induction
(RSI) with suxamethonium and cricoid pressure. ITU postoperatively
B Ramped head-up position, preoxygenation, and a RSI with rocuronium and cricoid pressure. HDU postoperatively
C Ramped head-up position, preoxygenation, and a RSI with suxamethonium and cricoid pressure. HDU postoperatively
D An awake fibreoptic intubation. Ward level postoperative care.
E Ramped head-up position, preoxygenation, standard induction
B
- C Ramped head-up position, preoxygenation, and a
RSI with suxamethonium and cricoid pressure. HDU
postoperatively
Obesity is on the rise in the UK. Weight loss surgery is also a growing field. The
procedures fall into two categories:
Restrictive
The commonest example of this type is the adjustable gastric band (AGB). Here a
fluid-filled band is placed around the proximal stomach creating a small pouch that
fills quickly with food creating the sensation of fullness. The band can be adjusted
by saline insufflation via a subcutaneous port. The AGB is now more popular
than the other types of restrictive treatment, such as the sleeve gastrectomy, and
luminal gastric balloon. The laparoscopic AGB is minimally invasive, reversible and
technically easier and safer than malabsorptive surgery. Complications often relate
to relative obstruction or reflux of food or gastric contents, such as oesophagitis.
Malabsorptive
The most common procedure of this type is the Roux-en-Y gastric bypass. This
surgically creates a small pouch of proximal stomach which is then plumbed
directly to the jejunum, ‘bypassing’ the duodenum altogether. Thus the stomach
firstly has an element of volume restriction, with the added benefit of a degree of
malabsorption. This makes the gastric bypass the gold standard weight loss surgery,
with body mass index (BMI) reductions of 10 kg/m2 possible in the first year alone.
It is irreversible, more complex, and has added complications including nutritional
deficiency and dumping syndrome
Preoperative assessment
Airway assessment should include neck measurement. Studies have shown that
obesity alone doesn’t predict difficult laryngoscopy, but alongside a Mallampati
grade III/IV or a high neck circumference, it does. Difficulty rates were 5% with
a 40 cm neck, rising to 35% with a 60 cm neck. Medical co-morbidities should
be assessed in the usual manner, but particular attention paid to screening for
obstructive sleep apnoea, pulmonary hypertension, right heart dysfunction and
heart failure. Functional testing in the form of cardiopulmonary exercise testing or
stress echocardiography may be indicated. Bariatric patients are regarded as high
risk of aspiration regardless of reflux symptoms and prokinetics, and antacids are the
norm
Operative factors
Induction often occurs in theatre on table to avoid moving and handling concerns,
but if required a hover mattress may be used for moving patients. The ideal position
is with the patient ‘ramped’ or ‘stacked’, this uses pillows and blankets to raise the
upper torso, shoulders and head to align the tragus of the ear with the angle of
Louis. This has been shown to improve direct laryngoscopy and should facilitate
preoxygenation by increasing functional residual capacity. A proprietary pillow, the
Oxford HELP pillow, is marketed in the UK for this purpose. The surgical position is
usually a modification of the Lloyd–Davis with steep head-up. A shelf is put at the
foot of the table to avoid slippage, and the arms are often out on arm boards. The
physiological strain of pneumoperitoneum is often well-tolerated, and ventilation is
sometimes better than expected due to the degree of positioning the chest above
the abdomen. Pressure point protection must be fastidious, as obese patients are
at high risk. Greatest risks are from venous thromboembolism, with an incidence of
about 5%, and low molecular weight heparin doses must be adjusted to weight as
per local protocol.
The crucial elements of the stem here are the presence of untreated obstructive
sleep apnoea (OSA), in determining postoperative care, and the airway assessment
influencing induction planning. From the outset this gentleman requires higher than
ward level care for his OSA and the gastric bypass procedure. HDU should suffice
unless he encounters any intraoperative obstacles. In terms of the induction, as
discussed the presence of obesity alone doesn’t equal a difficult laryngoscopy, but
increasing neck circumference is shown to correlate. His neck circumference does
not put him into the highest risks group. In any event, ramped positioning is crucial
to facilitate preoxygenation, laryngoscopy and mask ventilation (if required).
- A 62-year-old woman who presented for a laparoscopic cholecystectomy
experienced an unanticipated difficult intubation. An endotracheal tube was
eventually correctly sited following multiple attempts and the use of an intubating
stylet. The following day she is febrile with cervical surgical emphysema and
complains of neck stiffness and dysphagia.
What is the most likely cause of her symptoms?
A Oesophageal perforation
B Uvular necrosis
C Tracheal rupture
D Arytenoid dislocation
E Aspiration pneumonia
C
- A Oesophageal perforation
Repeated instrumentation during a difficult intubation can lead to significant
damage to the airway and surrounding structures resulting in potentially
fatal complications. An unrecognised oesophageal perforation can lead to
retropharyngeal abscess formation, acute mediastinitis, pneumonia and eventually
multi-organ failure and death. Early symptoms and signs can be non-specific;
therefore a high index of suspicion is crucial to avoid delays in management. The
case above contains strong risk factors for an oesophageal perforation which
includes female gender, age older than sixty years and a difficult intubation. Early
symptoms of perforation include sore throat, cervical pain, and cough, whilst fever
and dysphagia may indicate secondary bacterial invasion and abscess formation. Air
may also dissect along cervical fascial planes resulting in subcutaneous emphysema,
pneumomediastinum and pneumothorax. Management depends on lesion severity
and includes cessation of oral intake, intravenous antibiotics, parenteral nutrition
and if indicated surgical repair.
- A cardiac arrest call brings you to a 78-year-old man admitted to coronary care
following urgent percutaneous coronary intervention for inferior myocardial
infarction. The coronary care nurses administered a total of 3 mg of atropine 5
minutes ago for bradycardia. He is now has a blood pressure of 80/40 mmHg, a
heart rate of 35 beats per minute (regular), but is alert.
What is the next appropriate step in the management of his condition?
A Administer 500 μg atropine
B Start a dopamine infusion
C Urgent transvenous electrical pacing
D Start an adrenaline infusion
E Give a fluid bolus of 250 mL of colloid
D
- D Start an adrenaline infusion
The patient most likely has a symptomatic complete heart block that is usually
associated with an inferior myocardial infarction (MI). He demonstrates adverse
features in the form of hypotension; others to be concerned about include syncope,
heart failure or myocardial ischaemia.
The initial management would be administration of 500 μg of atropine intravenously
and assess the patient’s response. If the patient fails to respond to 3 mg of Atropine
in total, the next step is to start a second line agent such as an isoprenaline infusion
at 5 μg/minute or an adrenaline infusion at 2–10 μg/minute. Alternative drugs can be
considered such as aminophylline, dopamine, glucagon or glycopyrronium bromide,
however in a hypotensive patient, adrenaline is a more appropriate option.
Fluids are an appropriate option to treat hypotension without bradyarrhythmia
following an inferior MI but will not correct the cause of hypotension.
Transcutaneous and transvenous cardiac pacing are suitable alternatives to the
pharmacological treatment, the latter requiring significant expertise that might not
be immediately available, but is ultimately the aim.
- A 17-year-old girl presents for surgical correction of a spinal scoliosis. She has
dysmenorrhoea and menorrhagia for which she takes oral iron supplementation,
and is otherwise fit and well.
Her haemoglobin concentration is 101 g/L. The
surgeon reminds you that his current practice involves spinal cord monitoring in
these cases. Along with two large-bore peripheral cannulae, which of the following would be the most appropriate anaesthetic technique for this case:
A Volatile with target controlled infusion (TCI) remifentanil maintenance. An
internal jugular central line and a radial arterial line. Tranexamic acid.
B A radial arterial line. Propofol and remifentanil TCI. Cell salvage and
tranexamic acid.
C Volatile with nitrous oxide maintenance. A radial arterial line. Cell salvage and
tranexamic acid.
D Propofol and remifentanil TCI. A radial arterial line. A femoral central line and
cell salvage.
E TCI propofol with boluses of fentanyl. A radial arterial line with an internal
jugular central line. Tranexamic acid.
B
- B A radial arterial line. Propofol and remifentanil TCI. Cell
salvage and tranexamic acid
Operations on the spine are liable to cause serious complications, and the
understanding of the type of surgery and the general principles is essential to
prevent attendant morbidity. Massive haemorrhage requiring transfusion is one of
the most common, but respiratory or airway compromise, eye injuries (including
blindness), and spinal cord damage may also occur.
Spinal cord monitoring
Monitoring is used to try to reduce the risk of cord damage during surgery, and
uses electrophysiology to monitor two types of evoked potentials. Somatosensory
evoked potentials (SSEPs), are measured from the brain and receive small signals
from stimuli applied peripherally, usually to the posterior tibial nerves. These are
not affected by volatile anaesthetics, and signals may even be improved by muscle
relaxation as muscle tremor noise goes down. Motor evoked potentials (MEPs), are
larger signals applied to the motor cortex and measured by electrodes in the target
muscles. This type of monitoring allows for interrogation of the integrity of specific
tracts of interest and is increasingly used both in spinal and neurosurgery. Deep
neuromuscular blockade will abolish these measurements and volatile anaesthetic
concentrations above 0.5 MAC make the readings invalid, therefore if MEPs are to be
used total intravenous anaesthesia (TIVA) is the maintenance of choice.
Prone position
Essential for most surgery with a posterior approach, this is best accomplished with
diligence and an experienced team. The tracheal tube must be well fixed, and a ‘bail
out’ emergency plan for airway loss whilst prone must have been considered and
discussed amongst the team. The patient’s body must be supported at the level of
the mid chest (lower pectoral) and waist levels, leaving the abdomen relatively free
and uncompressed. There are ready made padding systems to deliver this position,
such as the Montreal mattress. If well positioned, there is less compression of the
inferior vena cava and less impairment of venous return. This avoids reduced cardiac
output and increased transmitted pressure into the epidural venous plexus (which is
vulnerable to pressure effects due to an absence of valves), and also reduces the risk
of lower limb thrombosis.
Once this position is safely achieved, meticulous detail must be paid to ensuring
pressure areas are well padded. Particular problems can be encountered with the
ulnar nerve at the elbow, as well as the brachial plexus. Avoiding traction on the
brachial plexus is achieved by ensuring the arms, if by the head, have the humeri
abducted to < 90° and the forearms lying slightly below the level of the chest. If the
arms are to be by the side, then the hands should be slightly supinated with the
thumbs pointing downward
Eyes
Spinal surgery has the highest rate of eye and visual complications. Postoperative
visual loss may result from two types of damage: ischaemic optic neuropathy
(ION) and central retinal artery occlusion (CRAO). Of the two, ION is by far the most
common. ION is thought to be caused by optic nerve hypoperfusion, and is linked
to intraoperative anaemia/massive blood loss, long surgery (especially > 6 hours),
obesity, and male sex. Interestingly diabetes and vascular disease are not clear risks
for ION. CRAO is caused by direct extrinsic pressure, and is mostly unilateral, and
seen with other sequelae of damage to the local area such as ptosis.
As described above in this case where cord monitoring is to be used, volatile
anaesthesia will detract from the readings ruling out stems A and C. Given the preexisting
history of anaemia and the type of surgery, most would regard the use
- A 75-year-old man with significant co-morbidities is admitted for elective foot
surgery under an ultrasound-guided ankle block.
In order to minimise the amount of time required to wait for the block to be
adequate for surgery, which one of the following nerves needs to be blocked first?
A Superficial peroneal nerve
B Deep peroneal nerve
C Sural nerve
D Saphenous nerve
E Tibial nerve
B
- E Tibial nerve
Ankle blocks are indicated for foot and toe surgery. They are easy to perform and
provide adequate analgesia for a variety of procedures on the foot. Five nerves
innervate the ankle; four are branches of the sciatic nerve (tibial, superficial and
deep peroneal, and sural) and one is a branch of the femoral nerve (saphenous
nerve).
Good anatomical knowledge is essential for a successful ankle block. Two of the five
nerves are deep (tibial and deep peroneal) and three are superficial (sural, superficial
peroneal and saphenous nerves) (Figure 10.2)..
Tibial nerve: This is one of the deep terminal branches of the sciatic nerve. The
nerve is divided into medial plantar and lateral plantar nerves, and also gives off
the calcaneal nerve. It innervates the plantar surface of the foot and heel. The tibial
nerve is blocked by injecting local anaesthetic (LA) behind the medial malleolus. The
injecting needle is advanced posterior to the pulsation of the posterior tibial artery.
Once contact with the bone is felt, the needle is withdrawn 2 mm, and 2–5 mL of LA
is injected at this point. The tibial nerve is the largest terminal branch of the sciatic
nerve and takes up to 20 minutes for the nerve block to be established. Therefore,
you should always start an ankle block with the tibial nerve. It is also the only nerve
in the ankle that can be identified by a nerve stimulator (plantar flexion of the toes).
Deep peroneal nerve: this nerve innervates the webbed space between the 1st
and 2nd toes. This nerve can be blocked just lateral to the tendon of extensor
hallucis longus (EHL). The tendon can be made more obvious by asking the patient
to dorsiflex the big toe. After palpating the dorsalis pedis artery lateral to the EHL,
the needle is introduced until a contact is made with the bone. The needle is then
withdrawn slightly and 2–3 mL of LA is injected after aspiration.
Saphenous nerve: This is a terminal cutaneous branch of the femoral nerve. It
descends on the medial side of the calf. It supplies the medial aspect of the leg
and the medial malleolus, and may also supply the medial margin of the foot. The
saphenous nerve is blocked with a subcutaneous injection of 5 mL of LA above the
medial malleolus.
Superficial peroneal nerve: This is a branch of the common peroneal nerve. It
travels down the leg between peroneus longus and peroneus brevis muscles. It
then runs under the deep facia in a groove between the peroneus brevis and the
extensor digitorum longus. After piercing the deep fascia, it becomes superficial in
the anterolateral compartment of the leg and then divides into superficial branches
that innervate the dorsum of the foot. Injecting 5 mL of LA subcutaneously along the
inter-malleolar line can block the nerve successfully.
Sural nerve: The sural nerve is derived from the tibial nerve in the popliteal fossa. It
is a superficial nerve and it travels down the posterior aspect of the leg and behind
the lateral malleolus. It supplies the lateral malleolus and the lateral margin of the
foot. Injecting 5 mL of LA in the midpoint between the Achilles tendon and the
lateral malleolus can block this nerve.
- You are asked to transfer a 27-year-old man to the local neurosurgical centre who
was admitted two hours ago with an acute traumatic subdural haematoma. On
admission he was alert but unable to recall the event, and he vomited twice. On
your assessment, he is asleep but rousable to voice, has slurred speech and is
obeying commands. His observations include a blood pressure of 180/90 mmHg,
heart rate of 90 beats per minute sinus rhythm and pupils of equal size and
reacting to light. He continues to vomit in spite of antiemetics.
What the most appropriate next step before the transfer?
A Perform an arterial blood gas
B Repeat the CT scan
C Rapid sequence induction
D Administer mannitol 20 % 0.5 g/kg
E Cool the patient
C
- C Rapid sequence induction
This patient needs urgent neurosurgical intervention to evacuate his haematoma.
His clinical picture suggests rapid progress of the haematoma. A new CT scan
would not add more the clinical picture and it may delay the transfer. Although an
isolated arterial blood gas sample is a useful result to have, it is unlikely to change
the outcome, speed or safety of transfer. A rise in intracranial pressure (ICP) may be
the cause of his deterioration but mannitol is only used as an acutely temporising
measure in a patient who is coning whilst waiting for surgery. Hypothermia for
management of acute brain injury is suggested to be beneficial for reducing the
cerebral metabolic rate of oxygen (CMRO2), but its acute use has not yet been
proven and, again, is unlikely to change the outcome of this patient.
However, the rapid neurological progress and ongoing vomiting renders a transfer
without a secure airway unsafe. Therefore rapid sequence induction and securing the
patients airway is the appropriate next step. This would also enable the anaesthetist
to optimise ventilation to control the intracranial pressure by targeting a Paco2 of
4.0–5.0 kPa.
- A 42-year-old man presents to the emergency department after an out-of-hospital
cardiac arrest. He was successfully defibrillated out of ventricular fibrillation after
20 minutes of cardiopulmonary resuscitation (CPR). The airway was secured and
the patient was transferred to hospital. The blood pressure is 120/76 mmHg without
the need for inotropes or vasopressors and he is coughing on the endotracheal tube.
There is no ischaemia demonstrated on his electrocardiogram (ECG).
What is the clinical action that is likely to be most beneficial?
A Administrating anti-platelet therapy via a nasogastric tube
B An urgent coronary angiogram
C An urgent transthoracic echocardiogram
D A CT pulmonary angiogram
E Targeted temperature management for 24 hours
E
- E Targeted temperature management for 24 hours
This is a difficult question. All are appropriate actions to ensure complete
management of your patient. The differential diagnosis of a sudden collapse is
broad, but most significantly could be:
• Arrhythmogenic (sudden acute arrhythmia such as ventricular fibrillation or
complete heart block);
• Cardiogenic (such as an acute myocardial infarction causing myocardial failure);
• Vascular (aortic aneurysm rupture);
• Obstructive (such as a pulmonary embolism);
• Intracranial event (such as a subarachnoid hemorrhage).
Making efforts to diagnose the cause of arrest will no doubt help in management.
For the options above: - There is no evidence of ischaemia on the ECG, suggesting no sudden occlusion of a
coronary vessel. Therefore anti-platelets may not be the key intervention. Similarly a
coronary angiogram may demonstrate unobstructed coronary arteries. - An urgent echocardiogram is vital to look at cardiac function. It is particularly
helpful at diagnosing a sudden ischaemic event (with regional wall abnormality)
or suggesting a pulmonary embolism (with a dilated right ventricle and high
pulmonary pressures). However since blood pressure is maintained without
augmentation it is questionable whether the echocardiogram will provide you
with information that will alter the management in the immediate-term. - A CT pulmonary angiogram is an important test and may provide a diagnosis.
With a normal blood pressure thrombolysis is not indicated. Treatment with
anticoagulation may be presumptively commenced (also indicated for coronary
vessel disease). - There is no option for an urgent CT head but this would also be a vital investigation
as an intra-cranial event may require emergency surgical management.
The question is asking for the most beneficial intervention, not the first. Therapeutic
hypothermia after out-of-hospital cardiac arrest has got a good body of evidence
that suggests improved neurological outcome and mortality outcomes at 6 months.
A recent study has demonstrated that a targeted temperature management
approach of 36°C is non-inferior to targeting a temperature of 33°C, the suggestion
is that a targeted approach and avoidance of pyrexia are more important than
the specific temperature chosen. Many departments would still opt to target a
temperature of 33°, but this practice appears to be decreasing.
13 A 59-year-old woman is on the high dependency unit following a bowel resection
for adenocarcinoma which finished 8 hours ago. She weighs 60 kg, has a past
medical history of type 2 diabetes and has a baseline creatinine of 120 μmol/L.
Postoperatively she has been passing 40 mL/hour of urine, which has decreased to
10 mL/hour for the past 2 hours despite her maintaining a normal blood pressure.
A repeat blood sample demonstrates a creatinine of 180 μmol/L
Which of this patient’s risk factors is most significant?
A Chronic renal impairment preoperatively
B Major intra-abdominal surgery
C Oliguria
D Serum creatinine rise
E Diabetes.
C
- D Serum creatinine rise
Acute kidney injury (AKI), is defined as an abrupt deterioration in renal function
occurring over 48 hours. The prevalence in hospitals is 1–7% and even a small rise in
creatinine is associated with an increased mortality, ranging from 10% to 80%.
In 2009 the National Confidential Enquiry into Patient Outcome and Death (NCEPOD)
published ‘Adding Insult to Injury’ which found that we were deficient in identifying
patients at risk of AKI and in 50% of cases our management could have been more
timely to prevent renal deterioration. This prompted the National Institute for Health
and Care Excellence (NICE) to publish recommendations highlighting the importance
of identification of risk factors and of prompt treatment
Risk factors include:
• Age over 65 years old
• Male gender
• Pre-existing renal disease
• Co-morbidities:
–– Congestive cardiac disease
–– Hypertension
–– Diabetes
–– Ascites
• Surgery:
–– Emergency
–– Prolonged, major surgery
–– Intra-peritoneal
• Anaesthesia:
–– Hypotension
–– Hypovolaemia
–– Blood transfusion
–– Nephrotoxic drug administration
The diagnosis may be made with either the RIFLE, AKIN or KDIGO classifications (the
latter two being very similar). They are based on RIFLE (Risk, Injury, Failure, Loss,
End-stage), which is a useful way to remember the steps to disaster, but the recent
modification is more sensitive and reflects recent evidence that even a small increase
in the serum creatinine concentration results in significantly increased morbidity and
mortality (see Tables 10.1 and 10.2).
To qualify for a particular stage the patient must meet either urine output or serum
creatinine criteria.
The patient described above has many risk factors that may pre-dispose her to
developing AKI. In addition to her co-morbidities, she has had intra-peritoneal
surgery in which crystalloid administration is often rationalised to prevent
anastomotic oedema and dehiscence.
Having six of the above risk factors infers a greater than 10% risk of AKI. The oliguria
described in the question does not meet AKI criteria by itself. The most evidencebased
concerning element in her story is her creatinine rise of 1.5 times her baseline
which indicates AKI stage 1 and is associated with a 10% mortality or greater
depending on how this situation progresses. Early intervention is indicated to
prevent further deterioration in the renal function
- A 72-year-old man with hypertension has been referred to you 2 days after having
an emergency laparotomy for an incarcerated hernia.
His oxygen saturations are 94% on an inspired oxygen concentration of 60%, his respiratory rate is 28 breaths per minute and on auscultation there is bi-basal crepitus. On examination the
blood pressure is 100/60 mmHg, the pulse is regular, the heart rate is 110 beats
per minute and the jugular venous pressure (JVP) is visible at 6 cm. He has passed
10 mL of urine per hour for the last 6 hours and is agitated.
What is the next appropriate course of action?
A Urgent blood tests to assess renal function
B Continuous positive airway pressure (CPAP) support in the high dependency
unit
C Urgent fluid administration of 5–10 mL/kg of fluid and assess response
D Admit to the intensive care unit for haemofiltration
E Intravenous administration of 40 mg of furosemide and 2.5 mg of diamorphine
A
- E Intravenous administration of 40mg of furosemide and
2.5 mg of diamorphine
This man has the following clinical issues: - Clinical evidence of pulmonary oedema with a raised jugular venous pressure
(JVP) - Hypotension with evidence of end-organ dysfunction (agitation)
- Acute kidney injury (AKI) Stage 1 on the basis of his urine output being less than
0.5 mL/kg/hour for 6 hours, according to the AKIN classification (see Table 10.2,
Question 13).
The pulmonary oedema may be due to different etiologies, either due to
excess intravascular fluid or ineffective cardiac activity. Excess intravenous fluid
administration for the treatment of oliguria post-operatively may be implicated.
Alternative possibilities include acute cardiac decompensation due to an ischaemic
cardiac event, electrolyte disturbance or a cardiac arrhythmia.
Acute heart failure should be managed with an ABC approach. Sitting the patient
upright reduces the central venous pressure and therefore the preload, which
can result in improved cardiac output. Oxygen therapy, intravenous access,
electrocardiogram, a chest radiograph, an arterial blood gas and repeat blood
science analysis including serum troponin concentration are all immediately
indicated. Treatment options include:
• Treat reversible causes:
–– Coronary reperfusion therapies
–– Anti-arrhythmic agents
–– Electrolyte correction
• To reduce the preload via venodilation:
–– Loop diuretic administration results in immediate venodilation
–– Diamorphine or morphine administration reduces central sympathetic activity
resulting in venodilation
–– Glyceryl trinitrate (GTN) infusion
• To reduce the preload by reducing circulating volume:
–– Loop diuretic administration results in delayed diuresis
–– Haemofiltration for accurate control of fluid balance
• To augment cardiac output:
–– Continuous positive airway pressure or non-invasive ventilation reduces
ventricular distention and improves cardiac contractility
–– Inotrope administration
–– Mechanical augmentation such as a intra-aortic balloon pump
• To provide cardiac or respiratory replacement:
–– Extra-corporeal membrane oxygenation
Regarding the options in the question, all interventions may be needed at some
stage. Investigations are important but take time to yield results and more urgent
action is required in this situation. Fluid administration may be used to treat
hypotension and oliguria but in the presence of pulmonary oedema (the more
pressing clinical priority) may be detrimental. That leaves us with management of
- The intensive care unit dietician suggests commencement of enteral nutrition on a
67-year-old patient.
Which of the follow represents an absolute contraindication to starting enteral
nutrition?
A Ischaemic bowel
B Small bowel anastomosis
C Short gut syndrome
D Paralytic ileus
E Pancreatitis
A
- A Ischaemic bowel
During critical illness or the perioperative period, it is important to consider every
patient’s nutritional status and requirements. Nutritional requirements should aim
to address any pre-existing malnutrition, support the catabolic response to surgery
or critical illness and aid rehabilitation. Malnutrition is associated with impaired
immunological function and increased morbidity and mortality.
The detection of acute malnutrition can be challenging and at present no
specific markers exist. Surrogate markers for chronic nutritional status include
anthropometric measures and biomarkers such as albumin, pre-albumin,
transferring and haemoglobin.
Following the advent of acute critical illness, the early (within 24–48 hours)
instigation of nutritional support has been demonstrated to improve patient
outcomes, however conflicting evidence exists concerning the merits of hypocaloric
verses normocaloric targets. Furthermore, the optimal method (continuous verses
bolus) and composition remains undefined.
The National Institute for Health and Care Excellence (NICE) recommendations for
assessing a patient’s nutritional requirements are summarised below:
There are published guidelines by NICE and The American Society for Parenteral and
Enteral Nutrition (ASPEN) in partnership with the Society of Critical Care Medicine
(SCCM), covering all aspects of nutritional support in the acute patient and critical
care settings. Though much debate continues with regard to the appropriate
indications for parenteral nutrition, most agree that it should not be commenced
unless the enteral route is inaccessible and likely to remain so for > 7days. The UK
CALORIES Trial published in October 2014 found no mortality difference between
enteral and parenteral routes of feeding critically ill patients. The current balance
of evidence suggests significant advantages of the enteral route that include less
infectious complications, thought to be secondary to reduced villous atrophy and
bacterial translocation within the gastrointestinal tract
Previous theories mandating ‘resting of the gut’ have been disproven. Traditionally
enteral nutrition was avoided in pancreatitis, however the British Society of
Gastroenterology now recommend enteral feed; there appears to be little difference
in outcomes between nasogastric or nasojejunal routes. Similarly paralytic ileus does
not preclude enteral nutrition and starting a low rate with vigilance for intolerance is
advised. Intolerance should be monitored through 4-hourly feeding tube aspirates
and prokinetics such as metoclopramide and erythromycin can be added pending
no contraindications. Bowel anastomosis should not prevent enteral nutrition
unless a concern regarding anastomotic leak exists. Short bowel syndrome results
in problems with malabsorption and high output stoma / fistulae. Enteral nutrition
can be trialed with the use of thickening agents; however it is likely that a combined
enteral and parenteral approach may need to be adopted. Enteral nutrition may
induce or worsen bowel ischaemia especially in the presence of hypotension and is
therefore not recommended in suspected or proven bowel ischaemia.
