ROCA Sept 2018

Question 1

a) What factors determine the intraocular pressure in a healthy eye?

Answer 1

1. Arterial blood pressure
2. Venous pressure
3. Partial pressures of PO2 and PaCO2
4. Partial pressures

Question 2

b) What key points would you need to know when assessing this patient preoperatively?

Answer 2

????????????????
1. Fasting time

2. RTA - cause? Medical cause underlying crash
   ECG
3. Other injuries
   Any life threatening injuries that require Rx prior to eye
4. Airway assessment
5. Other significant PMH / Prev anaesthetic

Question 3

C. The patient requires urgent surgery. Discuss your specific intraoperative management.

Answer 3

.

Question 4

d) What contraindications are there to performing a regional block in elective ophthalmic surgery?

Answer 4

.

Question 5

e) What different types of regional block are suitable for ophthalmic surgery?

Answer 5

.

Question 6

a) List the postoperative pulmonary complications that may occur following non-cardiothoracic surgery

Answer 6

Atelectasis
Pneumonia
Respiratory failure	
Pleural effusion	
Pneumothorax
Bronchospasm
Aspiration pneumonitis

Question 7

b) What are the patient related risk factors for postoperative pulmonary complications following non cardiothoracic surgery?

Answer 7

Age >60 years (good)  (good)

American college of anaesthesiologists II or more (good)

Functional dependency (good)  Congestive heart failure (good)  Chronic obstructive pulmonary  disease (good)

Smoking (fair)

Recent upper respiratory tract infection (fair)

Pulmonary hypertension (fair)

Delirium (fair)

Alcohol use (fair)
 
Weight loss >10% (fair)

Disseminated cancer (fair)

Question 8

b Surgery related risk factors for postoperative pulmonary complications following non cardiothoracic surgery?

Answer 8

Prolonged surgery (>3 h)

Surgical site: Abdominal, thoracic, neurosurgery, vascular, head and neck surgery (good)

Emergency surgery (good)

Question 9

c) How might anaesthesia contribute to postoperative pulmonary complications?

Answer 9

1. General > Regional

The combination of general anaesthesia, supine
positioning, opiates, and residual neuromuscular block reduces lung volumes and causes atelectasis in a spontaneously ventilating patient.

Poor use of Neuromuscular blocking agents (NMBAs), by failure to monitor correctly or excessive dosing, is associated with an increased risk of PPC

Anaesthetic agents diminish respiratory drive and the response to hypoxia and hypercapnia, resulting in hypoventilation. In a spontaneously ventilating patient, the closing capacity approaches FRC and the small airways collapse causing atelectasis in the dependent regions of the lung.

Hypoxaemia can result from ventilation–perfusion mismatching and increased shunt fraction. Prolonged periods of 100% oxygen may produce absorption atelectasis as all the oxygen is absorbed and the
splinting effect of nitrogen in the alveoli is lost.

Inadequate analgesia

The
effects of anaesthesia, bed rest, and opioids inhibit the cough
reflex and impair respiratory tract ciliary activity, while dry
gases result in mucus plugging. These physiological effects contribute to the development of PPCs.

Question 10

What perioperative strategies may you adopt to reduce postoperative pulmonary complications?

Answer 10

Preoperative
Optimization of existing cardiorespiratory disease (fair)

Early smoking cessation (fair)

Prehabilitation exercise programmes (insufficient data)

Intraoperative:

Minimally invasive surgical Techniques (fair)

Lung-protective ventilationvstrategies (fair)

Selective use of nasogastric tubes (good)

Short acting NMBAs with quantitative monitoring
(fair)

Neuraxial blockade (insufficient data)
Goal-directed fluid therapy (insufficient data)

Postoperative
Adequate analgesia (good)
Early mobilization (good)
Postoperative epidural analgesia (insufficient)
Lung expansion techniques (good)

Question 11

What is Guillain–Barré?

Answer 11

What is Guillain–Barré?
» Acute, immune-mediated, pre-junctional, ascending demyelinating
polyneuropathy affecting sensory, motor and autonomic nerves.

Question 12

What are causes of Guillain Barre?

Answer 12

> > Associated with respiratory
or gastrointestinal infection
(especially Campylobacter) in preceding weeks.

> > Autoimmune in nature –
antibodies attack the myelin sheath
or, more rarely, the axon itself.

Question 13

b) What are the clinical features of Guillain–Barré syndrome? (6 marks)

Answer 13

1 Variable presentation depending on subtype;
different forms associated with immune attack on different parts of the neurone.

Recovery is variable,
ranging from full recovery
to relapsing, remitting form.

2 >> Motor: 
typically ascending symmetrical weakness 
(flaccid, areflexic
paralysis), 
may ascend to involve respiratory muscles 
and also to cause
facial nerve palsies with 
bulbar weakness and opthalmoplegia.

> > Sensory:
ascending sensory impairment
associated with pain.

> > Autonomic: arrhythmias,
labile BP, urinary retention,
paralytic ileus,
hyperhydrosis, sudden death.

> > Miller Fisher syndrome:
this is a variant typified by ataxia, areflexia,
opthalmoplegia +/− weakness.

Question 14

d) What are the specific
considerations when
anaesthetising a patient
recovering from Guillain–Barré
syndrome?

Answer 14

Airway:
» Bulbar weakness,
poor cough, increased risk of aspiration.
Intubation required – consider need for rapid sequence induction.

> > May still have tracheostomy in situ
if still requiring ventilatory support or
assistance with secretion clearance.

Respiratory:
» Increased risk of pneumonia
secondary to aspiration and poor ventilatory
function. Make full assessment of this – history, nature of secretions, temperature, chest auscultation. Treat as required, delay non-urgent surgery if necessary.

> > Significantly reduced ventilatory capacity,
assess likelihood of requiring
noninvasive or invasive ventilation postoperatively.

Question 15

d) What are the specific
considerations when
anaesthetising a patient
recovering from Guillain–Barré
syndrome?

Answer 15

Cardiovascular:
» Autonomic instability, labile BP (with sensitivity to commonly used vasoactive drugs),
risk of arrhythmia.

Invasive monitoring indicated including cardiac output monitoring to guide fluid administration (ensure
full circulation as dehydration will exacerbate lability).

> > Prolonged illness,
multiple cannulations, access may be tricky.

Neurological:
» Neuropathic pain common –
may already be on antineuropathic drugs
+/− opioid analgesia.
Need to plan postoperative pain relief,
involve acute Cardiovascular:
» Autonomic instability, labile BP (with sensitivity to commonly used
vasoactive drugs), risk of arrhythmia. Invasive monitoring indicated
including cardiac output monitoring to guide fluid administration (ensure
full circulation as dehydration will exacerbate lability).
» Prolonged illness, multiple cannulations, access may be tricky.
Neurological:
» Neuropathic pain common – may already be on antineuropathic drugs
+/− opioid analgesia. Need to plan postoperative pain relief, involve acute

Question 16

d) What are the specific
considerations when
anaesthetising a patient
recovering from Guillain–Barré
syndrome?

Answer 16

Pharmacology:
» Suxamethonium: contraindicated due to risk of hyperkalaemia following
the development of extrajunctional nicotinic receptors.

> > Non-depolarising neuromuscular blocking agents: increased sensitivity – reduce dose.

> > Opioids: increased sensitivity to respiratory depressant effect in the presence of existing respiratory compromise, may already be taking
opioids and so dose adjustments may be necessary.

Question 17

d) What are the specific
considerations when
anaesthetising a patient
recovering from Guillain–Barré
syndrome?

Answer 17

Haematology:
» Risk of deep vein thrombosis due to prolonged immobility – continuation
of thromboembolic deterrent stockings and pneumatic compression
devices and pharmacological prophylaxis (check timing if planning
neuraxial technique).

Cutaneomusculoskeletal:
» Prolonged illness may be associated with weight loss – care with positioning and padding.
Renal:
» Check renal function – may dictate drug choices.

Question 18

What investigations are useful in GBS

Answer 18

Blood tests:
» Variable, not specific or sensitive: low sodium, renal dysfunction, raised
ALT and GGT raised CK.
» Elevated ESR +/− CRP.
» Antiganglioside antibodies (antibodies against a component of the axon
itself, increased association with Campylobacter, worse prognosis) in 25%.

> > Serology for Campylobacter, CMV, EBV, HSV or Mycoplasma pneumoniae
may be positive.
ABG may show development of respiratory failure.
Stool:
GI infections, especially Campylobacter.
CT brain:
Normal: to exclude other causes.
MRI spine:
Selective anterior spinal nerve root enhancement with gadolinium.
Lumbar puncture:
Normal cell count and glucose, elevated protein levels (although even this
may be normal early in the disease).
Nerve conduction studies:
Depends on subtype: majority show demyelinating pattern, some show
axonal loss.
Respiratory function tests:
Reduced vital capacity.

Question 19

Specific Rx for GBS

Answer 19

1. IVIG

2. PLEX

Question 20

a) Which investigations are specifically indicated in the
preoperative assessment of a patient presenting for
thyroidectomy for treated thyrotoxicosis? (5 marks)

Answer 20

1. Blood tests:
   » Thyroid function tests:
   confirm that the patient is euthyroid.

> > Full blood count:
carbimazole and propylthiouracil can cause
agranulocytosis. Check haemoglobin is adequate.

> > Two group and save samples:
potential for blood loss.

> > Calcium: check preoperatively as level may drop postoperatively due to loss of parathyroid glands.

ECG:
» Should show normal rate if euthyroid.
May be bradycardic if ongoing beta
blocker use.

Fibreoptic nasendoscopy:
» If concerns about likely ease of visualisation of larynx at laryngoscopy.

CXR or lateral thoracic inlet film:
» May indicate tracheal deviation or narrowing.

CT:
» Assess for retrosternal extension of goitre, tracheal compression.

Question 21

b) What particular issues must
the anaesthetist consider during
the induction, maintenance and
extubation phases of anaesthesia
for a euthyroid patient having a
total thyroidectomy? (11 marks)

Answer 21

Induction:
» Possibility of deterioration in tracheal compression on lying flat if large goitre (although this should have been elicited by preoperative questioning and investigations).
Head-up tilt for induction. Consider need
for smaller-diameter endotracheal tube.

> > Possibility of slower than usual intubation,
if difficult, and, therefore, hypoxia.

Pre-oxygenation required; consider use of high-flow nasal oxygen.

> > Choice of airway management is determined by preoperative investigations and discussion with the surgeon: straightforward intubation, asleep or awake fibreoptic intubation, awake tracheostomy.

Full difficult airway kit should be ready.
» Shared airway: armoured tube.
» If ‘can’t intubate, can’t ventilate’ (CICO) situation is encountered due to goitre size, obstruction is likely below the level of a cricothyroidotomy:
ENT surgeon ready for rigid bronchoscopy

Question 22

b) What particular issues must
the anaesthetist consider during
the induction, maintenance and
extubation phases of anaesthesia
for a euthyroid patient having a
total thyroidectomy? (11 marks)

Answer 22

Maintenance:
» Shared airway surgery, patient’s head distant to anaesthetist:

• Padding of eyes (extra care if exophthalmos).
• Secure taping of tube.
• Be alert to airway dislodgement or tube compression.

• Head-up tilt to improve venous drainage but not so as to impair arterial supply
.
• Extensions on fluid administration set.

• Long breathing circuit for anaesthetic machine.

> > Drugs:
• Maintenance via intravenous or inhalational route.

• Remifentanil useful to minimise need for further muscle relaxant and to achieve a degree of hypotension that will improve surgical field.
• Vasopressor, e.g. phenylephrine, may be useful to achieve normotension towards the end of surgery to test haemostasis.
• High risk of nausea and vomiting: give antiemetics.

Dexamethasone has added effect of reducing airway oedema.

• Plan for postoperative analgesia: important for blood pressure control postoperatively. Intravenous morphine towards end of surgery, regular paracetamol, NSAIDs if not contraindicated, oral morphine for breakthrough pain usually sufficient in addition to local anaesthetic
plus adrenaline infiltration by surgeon. Superficial cervical plexus blocks may also be used.

> > Thromboembolic prophylaxis: leg compression devices indicated due to surgery duration.

> > Warming mattress/forced air warmer and warmed fluids indicated due to surgery duration.

Question 23

b) What particular issues must
the anaesthetist consider during
the induction, maintenance and
extubation phases of anaesthesia
for a euthyroid patient having a
total thyroidectomy? (11 marks)

Extubation

Answer 23

Extubation:
» Assessment by surgeon for tracheomalacia (fibreoptic scope through tube, tube can be retracted to allow visualisation) or recurrent laryngeal nerve palsy (visualisation of vocal cords with laryngoscopy) if concerns.

Extubation can be deferred if such complications have occurred.

> > Risk of failure of haemostasis: aim for smooth extubation, can continue remifentanil infusion if used, ensure analgesia sufficient, sitting up.

> > Risk of laryngeal oedema increases the risk of problems at extubation: dexamethasone given intraoperatively, then manage extubation
in standard manner, ensuring patient sitting up, fully awake, fully reversed (assess train-of-four, appropriate dosing of neostigmine with glycopyrrolate, consideration of sugammadex use if high risk).

Question 24

c) Describe the specific
postoperative problems that may
be associated with this operation.
(4 marks)

Answer 24

> > Failure of haemostasis: causing airway compression, necessitating removal of clips on ward or urgent return to theatre.

> > Tracheomalacia: not detected prior to end of surgery, causing airway obstruction necessitating immediate reintubation. Rare.

> > Recurrent laryngeal nerve palsy: can be difficult to detect on direct visualisation prior to extubation. Uni/bilateral may cause stridor, difficulty
breathing. Unilateral may cause hoarse voice, difficulty phonating.

> > Laryngeal oedema: increased likelihood after complex surgery or difficult airway management.

> > Hypocalcaemia: due to trauma to or removal of parathyroid glands.

> > Pneumothorax: if retrosternal dissection has been necessary due to goitre size.

Question 25

b) What factors can lead to the development of high airway pressures during one lung ventilation (OLV)? (6 marks)

Answer 25

>> Check for obvious equipment failure such as disconnection. >> Check for double lumen tube or bronchial blocker dislodgement. >> Check for secretions or blood that may have occluded the tube. Assess for compliance, capnography waveform, oxygen saturations. >> Auscultate the chest (if feasible whilst patient is draped) and consider bronchospasm, pneumothorax of ventilated lung, inadequate paralysis

Question 26

A recent meta -analysis of Mallampati scoring of the airway found that it had a sensitivity of 60% and a specificity of 70%. a) Briefly define the terms systematic review (1 mark) and meta -analysis. (1 mark)

Answer 26

A systematic review attempts to gather all available empirical research by using clearly defined, systematic methods to obtain answers to a specific question. A meta-analysis is the statistical process of analyzing and combining results from several similar studies.

Question 27

b) Explain what is meant by sensitivity (2 marks) and specificity (2 marks) of Mallampati scoring of the airway in this meta - analysis.

Answer 27

The sensitivity of a clinical test refers to the ability of the test to correctly identify those patients with the disease or issue in question. The specificity of a clinical test refers to the ability of the test to correctly identify those patients without the disease or issue in question

Question 28

d) Rank the levels of scientific proof used to grade medical evidence. (4 marks)

Answer 28

1. Meta-analyses, randomised controlled trials (RCTs), or systematic reviews of RCTs. 2. Systematic reviews of, or individual, analytical non-RCTs such as case-control or cohort studies. 3. Non-analytic studies (for example, case reports, case series studies). 4. Expert opinion, formal consensus.

Question 29

e) List 8 factors that help to ensure a high-quality conclusion from a meta analysis. (8 marks)

Answer 29

Meta-analysis: a quantitative* systematic review of data from all available primary studies that are similar in nature, in order to reach a valid statistical conclusion to a question. Factors required for a high-quality conclusion: 1 Clearly defined question as the basis of the analysis. 2 Clear and reproducible methodology. 3 Comprehensive search of all available electronic databases based on appropriate search terms, ensuring non-English studies are included. 4 Clear and valid criteria for inclusion or exclusion of studies from the analysis, ensuring only studies of sufficient quality included. 5 Consider publication bias to avoid risk of over-representation of studies with a positive outcome.

Question 30

e) List 8 factors that help to ensure a high-quality conclusion from a meta analysis. (8 marks)

Answer 30

Meta-analysis: a quantitative* systematic review of data from all available primary studies that are similar in nature, in order to reach a valid statistical conclusion to a question. Factors required for a high-quality conclusion: 1 Clearly defined question as the basis of the analysis. 2 Clear and reproducible methodology. 3 Comprehensive search of all available electronic databases based on appropriate search terms, ensuring non-English studies are included. 4 Clear and valid criteria for inclusion or exclusion of studies from the analysis, ensuring only studies of sufficient quality included. 5 Consider publication bias to avoid risk of over-representation of studies with a positive outcome.

Question 31

e) List 8 factors that help to ensure a high-quality conclusion from a meta analysis. (8 marks)

Answer 31

Meta-analysis: a quantitative* systematic review of data from all available primary studies that are similar in nature, in order to reach a valid statistical conclusion to a question. Factors required for a high-quality conclusion: 1 Clearly defined question as the basis of the analysis. 2 Clear and reproducible methodology. 3 Comprehensive search of all available electronic databases based on appropriate search terms, ensuring non-English studies are included. 4 Clear and valid criteria for inclusion or exclusion of studies from the analysis, ensuring only studies of sufficient quality included. 5 Consider publication bias to avoid risk of over-representation of studies with a positive outcome.

Question 32

e) List 8 factors that help to ensure a high-quality conclusion from a meta analysis. (8 marks)

Answer 32

BJA Ed key questions What is the contemporary relevance of the study question? Is the study question clinically important? Is there uncertainty and debate? Is there demonstrable variation in practice? Is there a need to inform the design and conduct of a definitive, large trial? Are the findings novel? Has the question been adequately addressed by a previous systematic review (and how recently)? Key steps (i) Define the research question clearly and completely (ii) Check that the research question is unresolved (iii) Include an experienced meta-analyst, content expert (ideally, a triallist), and statistician (vi) Write a detailed study protocol outlining end points, inclusion criteria, and a search strategy, and publish it in advance on a publically available website (e.g. PROSPERO)6 (v) Be circumspect when interpreting the results; acknowledge the sources of bias; and consider heterogeneity, generalizability, and contemporary clinical relevance (vi) Report the study in such a way as to allow reproducibility of the results (PRISMA)5 or future updating of the systematic review

Question 33

You are asked to transfer an intubated intensive care patient for a magnetic resonance imaging (MRI) scan. a) What is meant by the term “magnetic resonance conditional” in relation to equipment used in the MRI scanner room? (1 mark)

Answer 33

MR Safe: these devices pose no MR-related hazards to patients or staff when used according to instructions and can therefore be used in any MR setting. MR Conditional: this equipment poses no MR-related hazard in a specified MR environment under specific conditions of use, e.g. static field strength, rate of change of magnetic field.

Question 34

b) What precautions should be taken to prevent burns caused by monitoring equipment used in an MRI scanner? (6 marks)

Answer 34

>> Use only MR safe monitoring equipment or MR conditional that has been deemed appropriate to use in that scanner. >> Check all equipment prior to use, that it is intact, that there is no breach in any insulating surfaces that might risk metal touching skin. >> Fibreoptic cables for ECG and pulse oximeter eliminate use of electrical current, which may result in induction currents and burns to underlying skin. >> Telemetric monitor to eliminate the risk of induction currents in connecting leads. >> ECG leads should be high impedance, braided and short to minimise risk of induction currents. >> ECG electrodes must be MR safe. >> Do not allow any cables to coil or cross each other as induction of current can result from capacitance coupling. >> Ensure leads are positioned to exit the scanner down the centre rather than at the side of the patient, close to the radiofrequency (RF) coils. >> Separate leads from patient’s skin with e.g. foam insulating padding.

Question 35

c) Describe other precautions you should take while this patient is having an MRI scan. (8 marks)

Answer 35

>> Equipment check: ensure all equipment to be used is MR safe or MR conditional and has been checked as safe to use on that scanner. >> Checklist: all staff and patients to complete checklist to ensure no contraindications to entering MRI scanner (see answer to d for more detail). >> Ferromagnetic objects: • Staff and patient to remove all ferromagnetic objects from clothes/ pockets to avoid the possibility of them becoming projectiles. * Ensure all equipment, e.g. trolley, is non ferromagnetic, remove oxygen cylinders etc. * Some clothes, e.g. sportswear, contain silver fibres – cotton hospital gown to be worn. * Drug delivery patches may contain metal – remove due to risk of burns. >> Padding over RF coils: ensure padding intact to prevent direct contact between patient and coils. >> Ear protection: for all patients, anaesthetised or not, due to high noise levels in scanner. >> Monitoring equipment and breathing circuit: check that there is sufficient length by checking planned range of movement of MRI stretcher before leaving the scanning room. >> Inaccessibility of airway: meticulous securing of airway to ensure it does not become dislodged as difficult to access once in scanner. >> Monitoring: telemetric monitoring to facilitate the presence of monitoring screen in control room, reduces risk of failing to notice abnormalities. >> Remote site anaesthesia: ensure senior support available, ensure orientation with equipment/location/emergency kit prior to commencement, especially as some equipment will be unfamiliar as it is MR safe and therefore different to that used elsewhere. Ensure identical monitoring standards to those used elsewhere can be achieved; awareness of low light levels often used in radiology. >> Risks of gadolinium-based contrast agents: • Avoid contrast if eGFR is less than 30 ml/min – risk of nephrogenic systemic fibrosis. • Do not repeat contrast within seven days. • Avoid in pregnancy unless absolutely necessary. • Drugs to manage anaphylaxis to be readily available.

Question 36

d) What are the relative/absolute contraindications to an MRI scan for any patient? (5 marks)

Answer 36

There are few absolute contraindications – most situations need further evaluation. >> Recent surgery involving ferromagnetic clips or implants. >> Ferromagnetic material in eye. >> Ferromagnetic cochlear implants. >> Ferromagnetic neurosurgical clips. >> Intra-aortic balloon pumps, ventricular assist devices. >> Ferromagnetic cardiac occluder devices within six weeks of implantation. >> Neurostimulators: some are safe for use in MRI. >> Programmable shunts/drug pumps: check for compatibility and check that exposure to MRI will not reprogram it. >> Pacemaker or ICD: risks of device failure, dislodgement and burns. However, some newer devices are MRI-compatible. >> Some aortic stent grafts.

Question 37

a) How should you manage the perioperative opioid requirements of a patient who is having elective surgery and who takes regular opioids for non-malignant pain? (8 marks) Post op

Answer 37

Postoperative: >> Regular input from inpatient acute pain team. >> Higher bolus doses of morphine in PCA will need to be kept under review regularly as equivalence calculations are approximate: the patient is therefore at risk of both unrelieved pain and narcosis. >> Use pain scores to assess for unrelieved pain. >> Be aware of signs of withdrawal (adrenergic hyperactivity, generalized malaise, abdominal cramps, yawning, and perspiration). >> Be aware of signs of overdosing (sedation, low oxygen saturations, reduced respiratory rate, small pupillary size). >> In view of the risk of either overdosing or withdrawal, it may be appropriate to manage the patient in a higher dependency setting than would normally be dictated by the nature of surgery, or extended recovery may be required. >> If intravenous morphine is used, convert back to oral dosing as soon as is feasible (consider any change in renal function postoperatively and its impact on opioid clearance).

Question 38

Conversion dose of PO Morphine for Tramadol Codeine Oxycodone

Answer 38

Drug Potency v morphine / equivalent 10mg dose Tramadol 0.15 67 mg Codeine 0.1 100 mg Oxycodone 2 5 mg

Question 39

Conversion dose of PO Morphine for Tramadol Codeine Oxycodone

Answer 39

Drug Potency v morphine / equivalent 10mg dose Tramadol 0.15 67 mg Codeine 0.1 100 mg Oxycodone 2 5 mg

Question 40

What is a spinal cord stimulator

Answer 40

Spinal cord stimulators (SCSs) are used for neuropathic pain, CRPS, and ischaemic pain due to angina or peripheral vascular disease. They achieve their effect through gate control theory and also modulation of release of other neurotransmitters. Leads are surgically placed in the dorsal epidural space (usually requires laminotomy) or percutaneously via Tuohy. During trial period, the pulse generator is left external to the body to check efficacy. The pulse generator can then be placed in a subcutaneous pocket (e.g. abdomen, gluteal) and the leads tunnelled subcutaneously to it.

Question 41

c) What are the perioperative implications of an existing spinal cord stimulator? (6 marks)

Answer 41

>> Preoperatively, make contact with the team who manages the patient to check battery life and any other issues. >> Bipolar diathermy should be used wherever possible. If unipolar absolutely necessary, position the return plate to avoid electrical passage through the SCS. >> Neuraxial block likely to be contraindicated (risk of infection or direct lead damage). If considered essential, consult the pain team who manages the patient’s SCS and perform under fluroscopic/ultrasound guidance to avoid the device.

Question 42

c) What are the perioperative implications of an existing spinal cord stimulator? (6 marks)

Answer 42

>> Preoperatively, make contact with the team who manages the patient to check battery life and any other issues. >> Bipolar diathermy should be used wherever possible. If unipolar absolutely necessary, position the return plate to avoid electrical passage through the SCS. >> Neuraxial block likely to be contraindicated (risk of infection or direct lead damage). If considered essential, consult the pain team who manages the patient’s SCS and perform under fluroscopic/ultrasound guidance to avoid the device.

Question 43

``` What additional perioperative precautions should be taken if the patient has an intrathecal drug delivery system fitted? (3 marks) ```

Answer 43

Intrathecal drug delivery systems (ITDDs) deliver drugs to the dorsal horn: opioids, local anaesthetic, clonidine or ziconotide for refractory pain or baclofen for spasticity. The pump may be external or fully implanted with reservoir filling performed percutaneously. It may have a fixed rate or be programmable. It may be sited anywhere from thoracic level to the second sacral segment. Risks: dural granuloma formation, leg oedema, infection. >> Spinal anaesthesia by lumbar puncture should be avoided, although intrathecal bolus may be given via the device if it is at a suitable level. However, the system will be primed with the usual drug it delivers, beware delivering a large bolus along with the intended bolus. >> Meticulous aseptic technique when utilising the ITDD to avoid risk of infection. >> Epidural anaesthesia is feasible above or below the ITDD site. >> Opioid dosing as for opioid naïve patient (unless patient also takes oral opioids). >> No diathermy within 30 cm of pump or catheter.