2. Perioperative Flashcards
Which of the options is most characteristic of a perioperative
myocardial infarction?
A. Occurs intraoperatively
B. Is associated with ST elevation
C. The patient complains of shortness of breath and chest pain
D. Has a mortality of up to 25%
E. Occurs secondary to mismatched oxygen supply and demand
D. Has a mortality of up to 25%
D. Has a mortality of up to 25%
D
Perioperative myocardial infarction (MI) can be difficult to diagnose as it usually presents without
the typical symptoms associated with myocardial ischaemia.
Further, the abnormal physiological
signs are common and can occur non- specifically in the perioperative setting. Two types of MI can occur. Type 1 is due to rupture or fissuring of plaques in response to tachycardia and hypertension and is compounded by the surgery- conferred pro- coagulant prothrombotic state.
Type 2 is associated with oxygen demand outstripping supply and pathological changes associated with both types are commonly found at post- mortem.
Less than 2% of perioperative MIs are associated with ST elevation. The vast majority are preceded by a period of ST depression.
Early mortality is high (as high as 25%) partly as there is no certainty over the best treatment in the perioperative phase.
Beta- blockers are known to further increase mortality and the risks of antiplatelet and antithrombotic therapies are greater at this time.
Proceeding to PCI is a complex decision in this period due to the requirement of dual antiplatelet therapy afterwards
Regarding the minimum standards of monitoring during anaesthesia and recovery, which of the following statements best reflects the most recent guidance?
A. The minimum standard of monitoring recommended varies with the seniority of the
anaesthetist
B. A processed electroencephalography (EEG) monitor is recommended when total
intravenous anaesthesia (TIVA) with neuromuscular blockade is employed
C. Temperature must be monitored during all cases
D. The minimum standard of monitoring recommended varies depending on the clinical area
E. If the minimum standards of monitoring cannot be met then anaesthesia should be
postponed or cancelled
E. If the minimum standards of monitoring cannot be met then anaesthesia should be
postponed or cancelled
E. If the minimum standards of monitoring cannot be met then anaesthesia should be
postponed or cancelled
The guidelines published by the AAGBI in December 205 state that the minimum standards of
monitoring apply whenever and wherever general anaesthesia, regional anaesthesia, or sedation
is given. If any required element is not available, it is up to the anaesthetist in charge to decide
whether to proceed without it. If so, they must document why it was not available for use.
Temperature should be monitored in cases lasting more than 30 min. It is recommended that the
processed EEG should be used alongside TIVA and neuromuscular blockade. Data derived from
it provide an additional source of information about the patient’s condition but their efficacy in
predicting awareness or predicting an adequate level of anaesthesia remains inconsistent and much
debated.
A 78- year- old woman is listed for emergency laparotomy. She has
presented with acute upper abdominal pain and a pneumoperitoneum
is evident on chest X- ray. Her medical history includes early Alzheimer’s
disease and osteoarthritis. Drug history includes galantamine and
diclofenac. The best plan regarding muscle relaxant use is:
A. Atracurium and wait for spontaneous inactivation
B. Atracurium and neostigmine
C. Rocuronium and sugammadex
D. Rocuronium and neostigmine
E. Suxamethonium
C
Alzheimer’s disease is associated with a loss of cholinergic neurons resulting in profound memory
disturbances and irreversible impairment of cognitive function.
Specific dementia treatment largely
comprises the use of acetylcholinesterase inhibitors. Galantamine is one such drug.
The anaesthetist should therefore be aware of the potential for interactions and consider avoiding neuromuscular blocking agents altogether.
However, if muscle relaxation is required it should be noted that suxamethonium paralysis may be prolonged. Larger doses of non-depolarizing neuromuscular blocking agents may be required to achieve sufficient paralysis. Neostigmine may be relatively ineffective (due to already present cholinesterase inhibition).
Larger doses of rocuronium can be
given safely in the knowledge that reversal can be achieved predictably with sugammadex.
A 65- year- old man presents to preoperative assessment before elective
inguinal hernia repair. He has no medical history and good exercise
capacity. You are asked to review his electrocardiogram (ECG), which
shows progressive prolongation of the PR interval culminating in a nonconducted
P- wave on a repeating four- beat cycle. The most correct
action now is:
A. 24- hour ECG
B. Echocardiography
C. Check electrolytes
D. Cardiopulmonary exercise testing
E. No further investigation required
- E
The ECG finding is second-degree atrioventricular (AV) block, Mobitz type (Wenckebach
phenomenon). A serial lengthening of the PR interval occurs with consecutive beats culminating
in a P-wave without a subsequent QRS before the cycle repeats itself. Mobitz type I is usually a
benign rhythm, causing minimal haemodynamic disturbance and with low risk of progression to
third degree (or complete) heart block. Asymptomatic patients with Mobitz type rarely require
treatment. Symptomatic patients usually respond to atropine. Permanent pacing is rarely required.
The patient reports no specific cardiac symptoms and is having peripheral surgery. They can
progress to surgery without delay for further investigation which is likely to be of low yield.
Mobitz type 2 is another form of second degree AV block which is at risk of deterioration to
complete heart block. It describes intermittent non-conducted P-waves without progressive
prolongation of the PR interval
You are asked to review a postoperative patient in recovery. He is
complaining of severe central crushing chest pain radiating down his left
arm. He appears grey and clammy and is very distressed.
Bedside ECG
reveals 4- mm horizontal ST segment depression in leads V1– V3, upright T- waves,
and a dominant R wave in V2.
The coronary artery most likely to be implicated is:
A. Posterior descending artery
B. Right marginal artery
C. Circumflex artery
D. Left anterior descending
E. Left marginal artery
- A
The clinical presentation and ECG findings are consistent with a posterior myocardial infarction. The
posterior wall is usually supplied by the posterior descending artery, a branch of the right coronary
artery in 80% of individuals.
The ECG findings provide a mirror/opposite of an anterior wall MI pattern. Thus, the lack of ST elevation in this condition means the diagnosis is often missed as ST
elevation becomes ST depression, Q waves become R waves, and T waves remain upright. The
posterior MI ECG is often held up to a light by the observer with the sheet turned back to front
and upside down to reveal a classic ST elevation patte
You have used a bronchoscope during a difficult intubation. The best
means of reprocessing the bronchoscope for use in another patient is:
A. Pasteurization
B. Chemical disinfection
C. Decontamination
D. Steam sterilization
E. Chemical sterilization
B
Decontamination is removal of contaminants prior to disinfection or sterilization. Pasteurization
uses hot water at 77 degrees for 30 min to achieve intermediate level disinfection. Sterilization
processes render an object completely free of all microbial life but is a harsh enough process to
damage various reusable medical equipment such as bronchoscopes. Chemical disinfection with 2%
glutaraldehyde is commonly used to disinfect scopes after decontamination.
- You assess a 60- year- old man for umbilical hernia repair as a day
case. His wife volunteers that he snores a lot during sleep. The most
discriminating sole predictor of obstructive sleep apnoea (OSA) is:
A. BMI >35
B. Age >50
C. Neck circumference ≥43 cm (7 inches)
D. Hypertension
E. Smoking
- C
All the answers represent criteria often assessed during obstructive sleep apnoea (OSA) risk scoring
such as in the STOP-BANG criteria. This is a mixture of patient questions and demographics as
follows:
· Snoring?—do you snore loudly, e.g. to be heard through closed doors?
· Tired?—do you often feel tired or sleepy during daytime?
· Observed—has anyone observed you stopping breathing, choking, or gasping during sleep?
· Pressure—do you have high blood pressure?
· BMI >35
· Age >50 years
· Neck circumference >43 cm (male) or >41 cm (female)
· Gender = male?
Each question scores a point and grades risk of OSA as low (0–2), intermediate (3–4), or high (5–
8). Increased scoring during STOP-BANG should prompt consideration of further screening tools
such as the Epworth Sleepiness Scale (ESS) or indeed investigation with sleep studies. While the
most common risk factor for OSA is obesity, the OSA tendency correlates best with increased neck
circumference
A 75- year- old man presents for elective total knee replacement. He
has well- controlled atrial fibrillation and is stable on rivaroxaban.
His U&E are normal. He experienced significant postoperative
nausea and vomiting after his last general anaesthetic and requests
regional anaesthesia. What is the best course of action regarding his
anticoagulation?
A. Continue rivaroxaban and proceed with general anaesthesia
B. Stop rivaroxaban seven days before surgery
C. Stop rivaroxaban the day before allowing 24 hours before spinal is performed
D. Allow 36 hours between last rivaroxaban dose and performance of spinal anaesthesia
E. Continue rivaroxaban and proceed with spinal anaesthesia
- C
Rivaroxaban inhibits platelet aggregation induced by Factor Xa.
It is used alone and in combination
with other drugs to prevent thrombus formation in those at risk of embolic stroke and as treatment
for VTE.
There is no reversal agent available. Such newer anticoagulants have led to adjustments in
the interval between discontinuation of the drugs and performance of neuraxial procedures, based
on the degree of risk of thrombosis.
Research has focussed on the pharmacokinetics of the drug and its effect on anticoagulant parameters by laboratory monitoring.
It is recommended that waitin for at least two half-lives to elapse is an adequate balance between the coagulation risks of stopping
treatment and the bleeding risk of developing a spinal haematoma. Half-life is commonly prolonged
in the elderly and for rivaroxaban is 7–11 hours so double would be 22 hours.
Platelet count is
unchanged with this drug and coagulation studies may not be helpful. Risk is further minimized by
avoiding multiple injection attempts, avoiding epidural catheter placement, and waiting for a period
of one half-life minus time to peak plasma concentration before restarting treatment
- A 36- year- old man requires laparoscopic colectomy for ulcerative
colitis. He is to be managed in accordance with local enhanced recovery
practices. The best way to provide postoperative analgesia to enhance
recovery for this patient is:
A. Patient- controlled analgesia (PCA) morphine
B. Thoracic epidural (local anaesthetic and fentanyl)
C. Spinal (local anaesthetic and diamorphine)
D. Wound catheter with lidocaine infusion
E. Bilateral transabdominal plane (TAP) blocks
- C
Enhanced recovery after surgery (ERAS) is a multidisciplinary and multimodal treatment package
delivered in the perioperative period to reduce postoperative morbidity and length of stay in
hospital by expediting return to normal physiology and function.
One aspect of this is providing effective analgesia with minimal detrimental effects.
Systemic opioids should be minimised where
possible as this slows return of gut function and necessitates the patient being connected to an
intravenous line.
Epidural analgesia, particularly thoracic, is the preferred analgesia regimen for open abdominal surgery but the risk/benefit ratio for laparoscopic surgery is different and epidural analgesia is generally not required.
Wound catheters work well in open surgery but their role is limited in laparoscopic surgery. TAP blocks are useful adjuncts but will not attenuate the stress
response intraoperatively and are unlikely to provide sufficient analgesia alone
- A 60- year- old man presents for a right total hip replacement. He has
Parkinson’s disease for which he takes levodopa and ropinirole. Which of
the following would be the best management plan perioperatively?
A. Stop his ropinirole but continue levodopa
B. Continue both his medications until induction and recommence as soon as possible
C. Withhold both his medications before surgery
D. Convert oral regimen to a subcutaneous apomorphine infusion prior to surgery
E. Convert oral regimen to transdermal rotigoline prior to surgery
- B
Although antiparkinsonian medications can interfere with many anaesthetic drugs their withdrawal can result in severe relapse of symptoms therefore it is very important that the usual antiparkinsonian medications continue with minimum disruption.
This patient should have all their
usual preoperative doses and should be able to eat and drink very soon after surgery.
There would be no need to add in anything else.
They should be able to resume their oral regimen quickly so careful assessment and management of postoperative nausea and vomiting is recommended.
Avoidance of dopamine antagonist antiemetic drugs (e.g. metoclopramide) is of paramount
importance given the directly opposing action on the dopamine agonist Parkinsonian treatments.
For patients who may not be able to manage anything orally or via the nasogastric route, e.g. if
requiring emergency intra-abdominal surgery, conversion to apomorphine or rotigotine may be
considered.
11 A 64- year- old man presents for renal stone fragmentation surgery
under general anaesthesia. He has a pacemaker in situ for sick sinus
syndrome. Which statement is the most accurate regarding pacemaker
management perioperatively?
A. Lithotripsy is contraindicated
B. Peripheral nerve stimulation should be avoided
C. A magnet should be placed over the pacemaker during surgery
D. Monopolar diathermy should be used in preference to bipolar diathermy
E. Rate modulator function should be deactivated prior to surger
- E
If a pacemaker has a rate modulator function this should be deactivated prior to surgery. Lithotripsy
is safe provided the lithotripter is >6 inches away from the pacemaker device.
Peripheral nerve stimulators are again considered safe provided they are used a safe distance from the pacemaker and not in a parallel axis with the pacemaker.
A magnet should not now be placed over a pacemaker
during surgery. They have unpredictable effects on the programming in modern pacemakers.
Bipolar is the preferred diathermy used.
2. A 55- year- old man is day 2 post operation following repair of a large
epigastric hernia. He is a smoker, has type 2 diabetes and chronic renal
failure stage 3. He is using a morphine PCA and has good pain relief but
complains of severe nausea. You decide to stop his morphine PCA and
replace it with oral oxycodone. When compared with oral morphine,
the benefit of oral oxycodone in this patient is:
A. It has more affinity for central mu receptors than peripheral
B. It is safer in renal failure
C. It does not require metabolism by cytochrome p450 CYP2D6
D. It has a second mechanism of action by increasing noradrenaline (norepinephrine) and
serotonin
E. It is more potent than morphine
- B
Oxycodone is a semi synthetic opioid that is commonly used in the postoperative period due to its
superior side effect profile when compared with morphine.
It has a potency twice that of morphine
and hence increased affinity for all receptors. This is relevant when converting from one to the
other and to be aware that the potential for addiction to opioid drugs is greater with those of
higher potency and faster onset.
Hence answer E is true but does not confer any benefit as pain is well controlled, so it is not the best answer.
There is no central versus peripheral preference to its
receptor binding but in the central nervous system (CNS) its action is greatest at supraspinal levels;
hence oxycodone is not suited to intrathecal or epidural use.
Oxycodone works only at opioid receptors mu, kappa, and delta.
It does not influence noradrenergic or seretonergic pathways.
This is a feature of tramadol and tapentadol.
When taken orally its absorption and distribution kinetics are similar to morphine however the
bioavailability is almost double: 70–80% compared with 30%. It is metabolized by hepatic enzymes,
and phase metabolism is dependent upon the cytochrome p450 pathway. The main enzyme
responsible for metabolism of oxycodone is cytochrome P450 3A4. This enzyme is inhibited
by many drugs including other opioids but is not subject to the pharmacogenetic variability of
CYP2D6. This enzyme is important in the metabolism and conversion of code in to its active form,
norcodeine.
The metabolites of oxycodone have only a fraction of the activity of the parent compound and do
not accumulate in renal failure as is a significant risk with morphine and its metabolite M6G.
3. A 60- year- old woman presents with a carcinoid tumour in her terminal
ileum. She has been experiencing weight loss, flushing, sweating, and
hypertension in the last six months. She is to have the tumour surgically
removed. What would be the best medication to treat her symptoms
preoperatively?
A. Phenoxybenzamine
B. Doxazosin
C. Methysergide
D. Octreotide
E. Aprotinin
- D
Carcinoid syndrome, although rare, can create serious problems to the anaesthetist, both by
the nature and variability of clinical manifestations and by the complications that can occur
perioperatively.
Carcinoid tumours are rare, slow-growing neoplasms of neuroendocrine tissues.
The classification of carcinoid tumours is based on the histological characteristics and site of
origin which includes lung, stomach, and small and large intestine.
As a group, carcinoid tumours
represent a wide spectrum of neuroendocrine cell types including enterochromaffin or Kulchitsky
cells, which have the potential to metastasize.
The cells typically contain numerous membranebound neurosecretory granules composed of hormones and amines. The most familiar of these
is serotonin, which is metabolized from its precursor, 5-hydroxytryptophan by a decarboxylase
enzyme.
The mediators released from these tumours when bypassing the hepatic metabolism, can
lead to the possible development of carcinoid syndrome.
This is a life-threatening complication
potentially seen as a carcinoid crisis, which can lead to profound haemodynamic instability, flushing,
and bronchospasm especially in a perioperative period.
The use of octreotide, a synthetic analogue
of somatostatin, has significantly reduced the perioperative morbidity and mortality. All these agents
in the question answer are potential treatments but octreotide is considered the first-line agent
