MCQ 2 Flashcards
1
Q
- The likely complications of laparoscopy include:
A. pneumothorax
B. shoulder pain
C. gas embolism
D. aspiration
E. left bundle branch block
A
A. true B. true C. true D. true E. false The problems associated with laparoscopy are caused by: • Intra-peritoneal insufflation • Absorption of carbon dioxide • Positioning • The surgical procedure Respiratory effects These effects are due to the: • Pneumo-peritoneum • Use of carbon dioxide as the insufflation gas • Position of the patient The lung volumes are reduced, especially the functional residual capacity (FRC) due to displacement of the diaphragm cephalad, reduced chest wall dimensions and muscle tone with a reduced intrathoracic blood volume. These changes lead to atelectasis, pulmonary shunting and hypoxaemia. Increased airway pressures may result in: • Barotrauma and pneumothorax • Increased physiological dead space • Reduced lung compliance • Hypercarbia as carbon dioxide is absorbed • Endobronchial intubation as the carina moves cephalad Cardiovascular effects Secondary to pneumo-peritoneum, the effects of the GA and positioning are: • Increased systemic vascular resistance • Increased mean arterial pressure • Decreased pre-load leading to reduced cardiac output • Ischaemia due to alterations in supply and demand• Arrhythmias – These may be ventricular due to rise in carbon dioxide tension or vagally mediated due to peritoneal traction • Cardiac failure Additional problems are: • Acid aspiration and regurgitation • Deep vein thrombosis • Trocar injuries to bowel and bladder • Bleeding • Postoperative nausea and vomiting • Venous gas embolism • Burns and explosions
2
Q
The likely results in an elderly, dehydrated man, breathing
room air with prolonged bowel obstruction include:
A. respiratory alkalosis
B. metabolic acidosis
C. hypoxaemia
D. uraemia
E. anaemia
A
A. true B. true C. true D. true E. false Bowel obstruction The clinical features of prolonged bowel obstruction include: • Vomiting, colicky abdominal pain, abdominal distension, absolute constipation (i.e. neither flatus nor faeces) • Dehydration and loss of skin turgor • Hypotension and tachycardia • Abdominal distension and increased bowel sounds • Empty rectum on digital examination • Tenderness or rebound indicates peritonitis
3
Q
The following are observed in a patient with acute
tubular necrosis:
A. normal blood creatinine and high blood urea
B. excretion of small amounts of highly concentrated urine
C. hyperkalaemia
D. progressive increase in central venous pressure
E. casts in the urine
A
A. false B. false C. true D. true E. true
Acute tubular necrosis Acute tubular necrosis (ATN) accounts for 85% of the intrinsic causes of acute renal failure (ARF).
Causes • 50% are due to ischaemia • 35% are due to toxins – inflammatory mediators, aminoglycosides, paracetamol, heavy metals and myoglobin The thick ascending limb (TAL) of the Loop of Henle is particularly predisposed to ischaemia for two reasons. 1. Although total blood flow to the kidneys is very high (25% of cardiac output) the majority is directed to the renal cortex. Medullary blood flow is limited so that the concentration gradient of osmolarity is preserved. 2. Active ion pumps in the TAL are high oxygen consumersThe combination of poor blood supply and high oxygen demand leaves this section of the tubule very vulnerable to ischaemia. Plasma biochemistry • Rising urea and creatinine • A metabolic acidosis, with or without hyperkalaemia Urinary analysis Loss or tubular concentrating ability in intrinsic ARF results in urine and plasma that are iso-osmolar. Typical findings: • Oliguria 30ml/h of dilute urine • Urine osmolarity 350mosmol/l • Urine sodium 20mmol/l • Urine urea 150mmol/l • Urine specific gravity 1,010 • Ratio of urine to plasma osmolarity 1:2 • Ratio of urine:plasma creatinine 20 • Pigmented casts in urine
4
Q
Platelet concentrates:
A. are viable for 2 weeks
B. must be filtered when administered
C. may cause significant histamine release
D. must be cross-matched
E. contain citrate
A
A. false B. true C. true D. false E. false ABO compatible platelet transfusions are desirable but not essential. Platelet concentrates contain small numbers of RBCs and leukocytes. They can be stored at 22C to 24C for 5 days but platelet function deteriorates after 48h. They are administered through a special filter, do not require cross matching, contain citrate as an anticoagulant and do not result in significant release of histamine.
5
Q
- Dopaminergic receptor blockers:
A. decrease gastric emptying
B. decrease renal blood flow
C. relieve motion sickness
D. are used as anti-arrhythmics
E. are used to treat Parkinson’s disease
A
A. true B. true C. false D. false E. false
The following types of agents have been used:
• Phenothiazines – a group of anti-psychotic (neuroleptic) drugs have a limited role in the treatment of vomiting
• Butyrophenones – effective in the prevention and treatment, of postoperative nausea and vomiting
• Benzamides
• Metoclopramide used as an antiemetic and prokinetic drug
• Antagonism of peripheral D1 receptors resulting in vasoconstriction of renal and mesenteric vasculature
6
Q
Injections of vitamin B12 are appropriate for patients
with anaemia due to:
A. Chron’s disease
B. a Vegan’s diet
C. epileptics on phenytoin
D. pregnancy
E. a gastrectomy
A
A. true B. true C. false D. false E. true Vitamin B12 is indicated in the following conditions:
• Individuals with pernicious anaemia
• Individuals with gastro intestinal disorders– Sprue, coeliac disease, regional enteritis, localised inflammation of the stomach or small intestine
• Partial and total gastrectomy when the antrum and intrinsic factor is lost
• Vegetarians who do not eat meat, fish, eggs, milk or milk products
7
Q
The following are associated with aortic incompetence:
A. rheumatic arthritis
B. syphilis
C. Ankylosing spondylitis
D. Marfan’s syndrome
E. AIDS
A
A. true B. true C. true D. true E. false
Causes and associations of aortic regurgitation are:
○ Acute regurgitation causes
• Acute rheumatic fever
• Infective endocarditis
• Dissection of the aorta
• Ruptured sinus Valsalva aneurysm
• Failure of a prosthetic valve
○ Chronic aortic regurgitation
• Rheumatic heart disease
• Syphilis
• Arthritides: Reiter’s syndrome, ankylosing spondylitis and rheumatoid arthritis
• Severe hypertension
• Marfans’ syndrome
• Bicuspid aortic valve
• Osteogenesis imperfecta
8
Q
Concerning fat embolism syndrome:
A. A petechial rash is essential for a certain diagnosis
B. A fall in haematocrit is characteristic
C. Mental changes may be due to hypoxia
D. There may be a pyrexia
E. It occurs more commonly in tibial fractures than femoral
fractures
A
- A. false B. false C. true D. true E. false
Fat embolism is most closely associated with fractures of the pelvis and long bones of the lower extremity.
○ Although injury is the main triggering factor leading to fat embolism syndrome, orthopaedic procedures such as hip arthroplasty and intra-medullary nailing for lower limb fractures may lead to the release of marrow fat into the circulation. Fat embolism may develop in any condition where there is potential for fat to be release into the circulation such as muscle injury and burns.
Of those patients who develop clinically evident fat embolism syndrome 20% show a fulminating course with mortality approaching 50%. The condition may occur at any age but it is most commonly seen in young males who are most at risk from serious trauma.
Clinical diagnosis
•PaO28kPa (60mmHg)
• Petechial rash
• Unexpected neurological signs Supportive changes
• Associated hypovolaemia and tachycardia
• Hypothermia
• Pyrexia
• Sudden reduction in haemoglobin
• Sudden onset of thrombocytopenia
• Increased erythrocyte sedimentation rate
• Fat globules in urine and sputum
• Retinal changes
9
Q
Intraocular pressure is normally:
A. 1.0 to 2.0 kPa above atmospheric pressure
B. increased by hypercarbia
C. reduced by non-depolarising neuromuscular blocking drugs
D. reduced by enflurane
E. reduced by trimetaphan
A
A. true B. true C. true D. true E. true Normal pressure is 15 to 25mmHg. Once the eye is opened intra-ocular pressure (IOP) is equal to atmospheric pressure. IOP is increased by hypoxia, hypercarbia, coughing and vomiting. All volatile agents cause a dose related decrease on IOP due to decreased extra-ocular muscle tone and increased aqueous humour outflow. Etomidate and propofol reduce IOP and thiopentone reduces it but to a lesser degree. Ketamine increases IOP and causes blephorospasm and nystagmus. All non-depolarising drugs lower IOP. Suxamethonium increases IOP possibly by contraction of the orbital smooth muscle. A peak increase occurs at about 4min returning to normal by 6min
10
Q
Pulmonary surfactant:
A. can be made synthetically
B. is found in amniotic fluid at full term
C. prevents alveolar collapse at low pressure
D. is made by type 1 pneumocytes
E. is a glycoprotein
A
- A. true B. true C. true D. false E. false Surfactant is a lipid surface tension lowering agent. Composition • Dipalmityl phosphatidyl choline 60%
• Phosphatidyl glycine 5%
•
Other phospholipids 10%
• Neutral lipoids 13%
• Proteins 8%
• Carbohydrates 2% Synthesis It is produced by type II alveolar epithelial cells (these are cuboid cells with large nuclei). Functions
• It lowers the surface tension in the alveoli, so increasing the compliance of the lungs and reduces the work of breathing
• Promotes alveolar stability
• Helps to keep the alveoli dry
11
Q
A maxillary nerve block in the pterygopalatine fossa
gives anaesthesia of the:
A. upper molars
B. upper incisors
C. soft palate
D. anterior two-thirds of the tongue
E. anterior part of the nasal septum
A
A. true B. true C. true D. false E. true
The maxillary nerve passes through the foramen rotundum into the pterygopalatine fossa and via the fissure into the infra-temporal fossa and continues as the infra temporal nerve.
The maxillary nerve gives off numerous branches:
• Meningeal branches within the cranium (dura mater)
• Ganglionic branches within the pterygopalatine fossa (to the pterygopalatine ganglion
• Zygomatic branches within the pterygopalatine fossa divide into two branches – facial and temporal – to the cheek and temple
• Posterior superior alveolar nerve divides into branches within the pterygopalatine fossa which supply the maxillary sinus, maxillary molar teeth, cheek and gums
• Middle superior alveolar nerve – from the infra orbital nerve to the maxillary sinus and upper premolar teeth
• Anterior superior alveolar nerve from the infra orbital nerve to the maxillary sinus and canine and incisor teeth
• Intraorbital nerve divides into palpebral, nasal and superior labial branches
12
Q
The following may contribute to acute renal failure
following abdominal surgery:
A. pre-existing upper respiratory tract infection
B. an induction dose of gentamycin
C. massive blood transfusion
D. endotoxaemia
E. obstructive jaundice
A
- A. false B. false C. true D. true E. true The possible causes of renal failure during the postoperative period are: Pre-renal • Hypovolaemia, inadequate pre-operative correction of third spaces losses, e.g. septicaemia, pancreatitis. These causesecretion of antidiuretic hormone (ADH), rennin and aldosterone and afferent arterial vaso-constriction • Low cardiac output • Hepato-renal failure associated with jaundice Renal • Old age • Pre-existing renal impairment • Renal ischaemia – thrombus or embolism • Hypoxia • Nephrotoxic drugs – NSAIDs, contrast media, gentamicin • Rhabdomyolysis • Hypercalcaemia, hyponatraemia Post renal • Ureteric obstruction by myoglobin, ligatures, fibrosis, tumours • Catheter – blocked
13
Q
Air embolism is especially dangerous in the presence of:
A. atrial septal defect (ASD)
B. ventricular septal defect (VSD)
C. tetralogy of Fallot
D. aortic stenosis
E. coarctation of the aorta
A
- A. true B. true C. true D. false E. false The rise in pulmonary pressures associated with venous air embolism may predispose to a right to left shunting in any condition in which a communication exists between the systemic and the pulmonary circulations. This will result in a systemic air embolism. Such conditions are an ASD, VSD, PDA and a patent foramen ovale, which may be present in up to 35% of all individuals in autopsy studies and other complex cardiac anomalies.
14
Q
Air embolism is especially dangerous in the presence of:
A. atrial septal defect (ASD)
B. ventricular septal defect (VSD)
C. tetralogy of Fallot
D. aortic stenosis
E. coarctation of the aorta
A
- A. true B. true C. true D. false E. false The rise in pulmonary pressures associated with venous air embolism may predispose to a right to left shunting in any condition in which a communication exists between the systemic and the pulmonary circulations. This will result in a systemic air embolism. Such conditions are an ASD, VSD, PDA and a patent foramen ovale, which may be present in up to 35% of all individuals in autopsy studies and other complex cardiac anomalies.
15
Q
Bilateral hilar lymphadenopathy is a recognised
feature of:
A. pulmonary tuberculosis
B. Hodgkin’s disease
C. erythema multiformis
D. systemic lupus erythematosus (SLE)
E. pneumoconiosis
A
- A. true B. true C. false D. false E. false The differential diagnosis of bilateral lymphadenopathy includes – lymphoma, pulmonary tuberculosis, carcinoma of the bronchus and sarcoidosis (erythema nodosum).
16
Q
The following can be derived from the blood gas analyser:
A. base excess
B. pH
C. PCO2
D. standard bicarbonate
E. actual bicarbonate
A
- A. true B. false C. false D. true E. true Blood gas analysers report a wide range of results, but the only parameters measured directly are: • The partial pressure of oxygen PO2 • The partial pressure of carbon dioxide PCO2 • Blood pHThe haemoglobin oxygen saturation (HbO2%) is calculated from the PO2 using the oxygen dissociation curve and assumes a normal P50 and that there are no abnormal forms of haemoglobin present. The actual bicarbonate, standard bicarbonate and base excess are calculated from the pH and PCO2 using the Siggard–Anderson nomogram. This normogram is derived from a series of in vitro experiments relating pH, PCO2 and bicarbonate. Anaesthesia and Intensive Care Medicine December 2002; 3: 474
17
Q
In a patient with a healthy heart transplant undergoing
elective non-cardiac surgery:
A. a resting heart rate of 50 beats/min is normal
B. the cardiovascular response to laryngoscopy is absent
C. atropine will cause a tachycardia
D. isoprenaline is the chronotrope of choice
E. anti-rejection therapy should be stopped preoperatively
A
- A. false B. false C. false D. true E. false The heart is denervated and will therefore only respond to circulating catecholamine. If there is no extra adrenaline stimulus the heart rate will be about 60bpm. In the presence of adrenaline there will be a high resting rate, in the absence of a vagal inhibition. Typically 100 to 120bpm. A slowing heartbeat is a sign of rejection. The cardiovascular responses to laryngoscopy are still evident via the adrenal axis but they are often delayed. There is no vagal tone in the transplanted heart therefore atropine is ineffective as a chronotope. Isoprenaline is the drug of choice in a bradycardia. Anti-rejection therapy should be monitored. BJA 1990; 67: 772–778
18
Q
Low molecular weight heparin:
A. activity is effectively measured by activated partial
thromboplastin time (APTT)
B. strongly binds to plasma proteins
C. has a longer plasma half-life than a standard heparin
D. has its effect reversed by an equivalent dose of protamine
E. has a prolonged plasma clearance in patients with renal failure
A
- A. false B. false C. true D. false E. true Low molecular weight heparins are derived from the depolymerisation of heparin by either chemical or enzymatic degradation. Compared to unfractionated heparin, low molecular weight heparins are more effective at inhibiting factor Xa and less effective at promoting the formation of the inactive “anti-thrombin – thrombin” complex. Advantages • Single daily dose due to a longer half-life • Less effective on platelets • Reduced affinity for von Willebrand factor• Reduced risk of heparin induced thrombocytopenia • Reduced need for monitoring coagulation Protamine is not fully effective in reversing the effects of low molecular weight heparin.
Kinetics • Administered subcutaneously once a day (bioavailability is 90% from the subcutaneous route)
• The half-life is 12h, which is 2 to 4 times longer than standard heparin
• Less protein bound than standard heparin
• Renal elimination and the t1/2 increases with renal failure
19
Q
Low molecular weight heparin:
A. activity is effectively measured by activated partial
thromboplastin time (APTT)
B. strongly binds to plasma proteins
C. has a longer plasma half-life than a standard heparin
D. has its effect reversed by an equivalent dose of protamine
E. has a prolonged plasma clearance in patients with renal failure
A
20
Q
Intrinsic (auto) positive end expiratory pressure (PEEP):
A. can be achieved by reversing the I:E ratio
B. does not result in air trapping when compared to
extrinsic PEEP
C. can be easily monitored in ITU patients
D. has the same effect as extrinsic PEEP on haemodynamic
values
E. requires an extra work of breathing to initiate a
spontaneous breath
A
- A. true B. false C. true D. true E. true Auto PEEPi (intrinsic PEEPi) is the difference between the alveolar pressure and the airway pressure at the end of expiration. It exists when expiration continues right up to inspiration (i.e. there is no expiratory pause). PEEPi occurs when there is: • An obstruction to expiratory flow – asthma, chronic obstructive ariway disease (COAD) • When the expiratory time is too short – rapid respiratory rate, prolonged inspiratory time Newer ventilators usually have a means of checking the PEEPi level. It is important to note that the value on the pressure dial of ventilators during expiration does not reflect the level of PEEPi in the lung. When beneficial, PEEP increases FRC by alveolar recruitment. This reduces pulmonary venous admixture and increases PaCO2 at any given FIO2. However PEEP may produce unpredictable effects especially if lung compliance is dyshomogeneous, as in pneumonia or volume-controlled ventilation. PEEP will increase peak airway pressure and may cause over distension of lung units, hence: • Barotrauma is a risk • Compression of vessels around distended alveoli may divert blood to underventilated regions, hence:– Increased physiological dead space– Worsen the shunt fraction– Increased pulmonary vascular resistance (PVR)
21
Q
The effects of ecstasy (3,4-methylene
dioxymethamphetamine):
A. are dose related
B. include hyperpyrexia, hypercalcaemia and hyperkalaemiaC. are due to inhibition of 5-hydroxytryptamine (5-HT)
D. are due to drinking large amounts of water
E. include renal failure due to rhabdomyolysis
A
- A. false B. true C. false D. false E. true Ecstasy (3,4 methylenedioxymethamphetamine – MDMA) is an amphetamine derivative. MDMA causes the release of 5-HT, one of the neurotransmitters Paper 1 Answers 150 implicated in the control of mood. In primates it causes irreversible loss of serotonergic nerve fibres. 5-HT is a neurotransmitter triggering the thermoregulatory centre in the hypothalamus to increase body temperature. Acute effects include: • Empathy • Heightened alertness • Acute psychosis • Trismus • Tachycardia Positive effects tend to lessen with regular use while negative effects increase. The main problems in the management of these patients are: Acute toxicity Hyperthermia, muscle rigidity, obtunded consciousness and fitting. There appears to be no relationship between effects and the dose. A syndrome similar to malignant hyperpyrexia can occur with rhabdomyolysis, DIC and MOF. Rapid cooling and the use of dantrolene have been recommended if the core temperature is 40C. Drinking large amounts of water at raves to prevent dehydration causes dilutional hyponatraemia and cerebral oedema. Acute liver failure may occur due to either a reaction to ecstasy itself or a reaction to a contaminant. Hall. Ecstasy and Anaesthesia. BJA 1997 [Editorial]
22
Q
The following arrest the heart in diastole:
A. hypercalcaemia
B. hyperkalaemia
C. acidosis
D. hypothermia
E. digitalis overdose
A
- A. false B. true C. false D. true E. false
23
Q
Exposure to nitrous oxide 20% in oxygen for a
prolonged time causes:
A. sedation
B. respiratory depression
C. abdominal distension
D. leukopenia
E. vitamin B12 deficiency
A
- A. false B. false C. true D. true E. false Nitrous oxide affects vitamin B12 synthesis by inhibiting the enzyme methionine synthetase. This effect is of importance if the duration of the nitrous oxide anaesthesia exceeds 8h.Nitrous oxide also interferes with folic acid metabolism and impairs the synthesis of DNA. Prolonged exposure may cause agranulocytosis and bone marrow aplasia. Exposure of patients to nitrous oxide for 6h or longer may result in megaloblastic anaemia.
Occupational exposure to nitrous oxide may result in a myeloneuropathy. This condition is similar to sub acute combined degeneration of the spinal cord and has been reported in some dentist and in individuals addicted to the inhalation of nitrous oxide.
24
Q
A pregnant lady who had an accidental dural tap
and presented with headache, photophobia and
hyperaesthesia of both lower limbs would be most
appropriately treated with:
A. reassurance and review in 2 h
B. neurosurgical consultation
C. emergency CT scan
D. epidural saline
E. epidural blood patch
A
25
A likely complications of infraclavicular block of
the brachial plexus is:
A. recurrent laryngeal nerve paralysis
B. pneumothorax
C. air embolism
D. phrenic nerve paralysis
E. haemopericardium
23. A. false B. true C. false D. false E. false Performance of this block takes advantage of the tight neural bundle containing the brachial plexus in the infraclavicular area, anterior to the coracoid process before the nerve fibres enter the axilla. At the mid-point of the clavicle the plexus liesapproximately 3 to 5cm from the skin surface and is posterior and lateral to the subclavian artery. Complications include pneumothorax, haemothorax, and chylothorax (with a left sided block).
26
Withdrawal of life support treatment in ITU is based on:
A. age
B. patient autism
C. acute physiology and chronic health evalution (APACHE)
score
D. predictable treatment outcome
E. clinical decision
24. A. false B. true C. false D. true E. true The ethical and legal dilemmas of withdrawing or withholding life saving treatment in children are discussed by Street K. Street K. British Journal of Intensive Care 1999: 165–166
27
Stimulation of the 5th cranial nerve during posterior
fossa surgery can cause:
A. jaw jerk
B. facial muscle twitching
C. bradycardia
D. shoulder jerking
E. nystagmus
A. true B. false C. true D. false E. false Stimulation of the trigeminal nerve during posterior fossa surgery may cause arrhythmias, severe hypertension and bradycardia. The motor nucleus are in the pons leading to masseter contraction, the sensory nuclei are in the medulla, mid-brain and pons. Vagal stimulation may occur leading to hypotension and bradycardia.
28
Chronic alcohol intake is associated with:
A. malnutrition
B. mean corpuscular volume (MCV) of 90
C. decreased gastric motility
D. decreased stress response to surgery
E. increased serum albumin
. A. true B. true C. true D. true E. false Considering that 15% of the population are said to be alcoholics and that 10% or more of hospital admissions are related to alcohol abuse, it is curious that anaesthetists do not encounter more problems with such patients. Alcohol is a potent toxin that affects all systems. Cardiovascular Chronic abuse can lead to global cardiomyopathy, pulmonary hypertension, arrhythmias. Thiamine deficiency can lead to high output cardiac failure. Central nervous system Chronic ingestion may cause neuropsychiatry abnormalities. Neuropathy and myopathy may occur. GIT Gastric hyperacidity, gastroparesis and reflux oesophageal diseases are common. Portal hypertension secondary to cirrhoticliver disease causes oesophageal varices. Haematology anaemia nutritional deficiency and or chronic gastrointestinal blood loss. Hepatic The liver has a huge functional reserve and can continue to metabolise most drugs even in the presence of widespread pathological changes. Protein metabolism is decreased so levels of coagulation factors may be reduced (prolonged PT). Albumin levels are reduced (decreased binding of drugs). Immune system Excessive alcohol consumption is immunosuppressive. Respiratory system
• Ciliary dysfunction
• Leukocyte inhibition
• Surfactant inhibition
• Postoperative chest infection
Metabolism
• Tendency to hypoglycaemia
• Withdraw symptoms
29
The appropriate drug treatment of acute
bronchoconstriction in children includes:
A. isoprenaline
B. ketamine
C. adrenaline
D. sodium cromoglicate
E. atropine
27. A. false B. false C. false D. false E. false The appropriate drug treatment of acute bronchoconstriction includes:
• Oxygen in as high a concentration as possible
•-2 agonists starting with nebulised salbutamol in oxygen 2.5 to 5mg and repeated. If there is no response or deterioration, this may be given intravenously at a dose of 3 to 20g/min
• Anticholinergics – Nebulised in oxygen ipratropium bromide 250 to 500g, synergistic with -2 agonists
• Aminophylline – This is a controversial drug and is generally used in patients who have failed to respond to the above therapy
• Steroids – The role of steroids in the acute severe bronchoconstriction is established and they should be given early after presentation of symptoms
• Fluids and electrolytes
• Regular assessment
• Other less well established treatments include: magnesium, adrenaline, ketamine, inhalation volatile anaesthetic agents and helium
30
Complications of a coeliac plexus block include:
A. constipation
B. hypertension
C. urinary retention
D. headache
E. impotence
28. A. false B. false C. false D. false E. true The potential complications of coeliac plexus block are: • Injection into aorta, vena cave, left renal artery • Intraperitoneal injection
• Retroperitoneal haematoma
• Backache
• Hypotension Paper 1 Answers 154
• Diarrhoea
• 0.15% risk of paralysis
• 3% risk of impotence
• Acute ischaemic myelopathy
31
A decrease in hypoxic response to ventilation is seen in:
A. patients at high altitudes
B. cyanotic heart disease
C. awakening from halothane anaesthesia
D. iv PCA (patient controlled analgesia)
E. pulmonary fibrosis
29. A. false B. false C. true D. true E. false
32
Myotonic dystrophy is associated with:
A. sternomastoid muscle wasting
B. diabetes mellitus
C. frontal baldness
D. thyroid adenomata
E. myasthenia gravis
30. A. true B. true C. true D. false E. false
This is an intrinsic muscle disorder.
There is delayed muscle relaxation due to an abnormal closure of the sodium/chloride channels following depolarisation. This causes repetitive discharge and contraction. Clinical features
• General classic triad: frontal baldness/cataracts/mental retardation
• Skeletal muscle atrophy leading to weakness of facial, neck, respiratory and distal musculature
• Failure of muscle relaxation (myotonia) following voluntary or induced contraction (shivering, TENS, diathermy)
• Pharyngeal muscle weakness, which may lead to aspiration
• Cardiac problems – first degree heart block, mitral valve prolapse (20% of cases), cardiomyopathy
• Endocrine problems – gonadal atrophy, infertility, diabetes mellitus, hypothyroidism, adrenal insufficiency
• Respiratory system – central sleep apnoea • Symptoms deteriorate during pregnancy (uterine atony)
33
Myotonic dystrophy is associated with:
A. sternomastoid muscle wasting
B. diabetes mellitus
C. frontal baldness
D. thyroid adenomata
E. myasthenia gravis
34
Pulmonary artery shunting is seen in:
A. tetralogy of Fallot
B. atrial septal defect
C. pulmonary stenosis
D. ventricular septal defect
E. coarctation of the aorta
31. A. true B. true C. false D. true E. false This occurs in any condition in which communication between systemic and pulmonary circulation is present allowing a right to left shunt. ASD, VSD, PDA, tetralogy of Fallot, patent foramen ovale.
35
Hepatic encephalopathy is precipitated by:
A. surgery
B. constipation
C. oral neomycin
D. haemorrhage
E. benzodiazepines
A. true B. true C. false D. true E. true Hepatic encephalopathy is a metabolic disorder of the central nervous system and neuromuscular system that may complicate liver failure from any cause. It is particularly associated with advanced cirrhosis on account of the diffuse parenchymal damage and post systemic shunting. The condition may be precipitated by: • Diarrhoea – Hypokalaemia increases renal ammonia production. Alkalosis increases the amount of ammonia that crosses the blood brain barrier • Constipation • Diuretics • Vomiting • GIT bleeding • Infection • Sedatives • Paracetamol • High protein diet • Metabolic disturbance, e.g. hypoglycaemia
36
Concerning interosseous injection:
A. It is the route of choice in the resuscitation of small children
B. Swelling around the needle is not a reason for
discontinuation
C. Aspiration of marrow confirms the position
D. The humerus is preferable to other bones
E. Only crystalloid can be given
A. false B. false C. true D. false E. false If intravenous cannulation is difficult an interosseous infusion can provide emergency vascular access in children less than 6 years of age.
A rigid 18G spinal needle within a stylet or shorter bone marrow trephine needle can be inserted into the distal femur or proximal tibia.
If the tibia is chosen, a needle is inserted 2 to 3cm below the tibial tuberosity at a 45angle to the skin and away from the epiphyseal plate.
Once the needle is advanced through the cortex it should stand upright without support.
Proper placement is confirmed by the ability to aspirate marrow through the needle.
The interosseous route is effective for:
• Fluid therapy
• Drugs epinephrine (use a higher dose than recommended for iv route)
• Induction and maintenance of anaesthesia
• Antibiotics
• Seizure control
• Inotropic support
here is a risk of osteomyelitis and compartment syndrome so it is recommended that the iv route should be established as soon as possible
37
34. The following are used in the direct calculation of P(A-a)O2:
A. C(a-v)O2
B. oxygen delivery
C. oxygen consumption
D. alveolar nitrogen tension
E. respiratory quotient
A. false B. false C. false D. false E. true The alveolar to arterial oxygen difference is the difference between the partial pressure of oxygen in the alveoli and the arterial partial pressure of oxygen.
The mean alveolar PAO2 is calculated using the alveolar air equation:
PAO2 =PIO2- PACO2/R+F where:
•PIO2is the partial pressure of inspired oxygen
•PACO2is the partial pressure of alveolar carbon dioxide
• R (the respiratory quotient) is normally between 0.7 and 0.8
• F is a correction factor
The PaO2 is obtained from arterial blood gas analysis.
The P(A-a)O2 is normally 1 to 2kPa or 5 to 10mmHg.
The difference is due to physiological shunts.
It normally increases with age and inspired oxygen concentration.
38
Old age is associated with:
A. an increased minimum alveolar concentration (MAC) value
for volatile agents
B. resistance to non-depolarising drugs
C. a decreased functional residual capacity (FRC)
D. sensitivity to morphine
E. decreased autonomic function and efficiency
35. A. false B. false C. false D. true E. true The effects of old age on morbidity and mortality in anaesthesia are: Cardiovascular system • Ischaemic heart disease • Impaired cardiac performance • Impaired perfusion of vital organs • Atherosclerosis and hypertension Respiratory system
• Increase closing capacity
• More airway collapse and greater A-a difference
• Decreased sensitivity to carbon dioxide
• Increased incidence of atelectasis, pulmonary embolism and postoperative chest infection Nervous system •
Cerebrovascular impairment
• Hearing and sensory impairment
• Confusion Pharmacology
• Increased sensitivity to sedatives, opioids and other drugs
• Impaired drug distribution, metabolism, elimination
• Altered plasma proteins and drug binding to proteins Metabolism
• Slower metabolic rate
• Impaired renal blood flow and function
• Impaired fluid balance and especially dehydration
• Tendency to diabetes mellitus
• Malnourishment Other considerations
• Physically frail with liability to damage of skin, bones, impaired temperature control
• Increased likelihood of gastro-oesophageal reflux
• Cervical spondylosis and arthritis with limitation of movement • Thin skin
39
The treatment of pre-eclampsia with magnesium sulphate
administration is associated with:
A. depression of cardiac output
B. epileptiform convulsions
C. depression of uterine activity
D. potentiation of depolarising muscle relaxants
E. potentiation of non-depolarising muscle relaxants
36. A. false B. false C. true D. true E. true
The efficacy of magnesium is now established and should be the first line therapy.
The Collaborative Eclampsia Trial showed it to be clearly superior to phenytoin and diazepam.
Magnesium works by preventing cerebral vasospasm through the block of calcium influx via NMDA glutamate channels. Magnesium sulphate is the drug of choice in eclampsia because it is more effective than diazepam and phenytoin in preventing fits and it minimises maternal mortality. Magnesium therapy
• Dose 4g bolus over 10min iv followed by an infusion of 1 to 2g/h
• Therapeutic blood levels are 2 to 3.5mmol/l Paper 1 Answers 158
• Treatment is continued for 24h after the last seizure. Magnesium 1g 4mmol Magnesium in anaesthesia
• Reduces acetylcholine release
• Decreases the sensitivity of the motor end plates to acetyl choline thus increasing the sensitivity to both depolarising and non-depolarising drugs
• Placental transfer causes poor neonatal muscle tone and respiratory depression
• Reduces uterine contractility (tocolytic)
40
Acute herpes zoster infection:
A. typically involves thoracic dermatomes
B. is caused by an RNA virus
C. treated promptly with steroids will not progress to post
herpetic neuralgia
D. may cause pain lasting more than 3 months
E. involves first and second order sensory neurones
37. A. true B. false C. false D. true E. true
Viral properties
• Double stranded DNA virus
• Primary infection usually in first decades
• Establishes a latent infection in the dorsal root ganglion. Recurrent disease caused by a viral reaction Disease loci
• Dorsal root ganglion especially the thoracic dermatomes • Pain deep aching or burning
• Dysaesthesia, paraesthesia
• Allodynia
• Post herpetic neuralgia pain 1 month after eruption may persist for 3 months
41
Surgical correction of scoliosis:
A. carries a high risk of spinal cord damage
B. is facilitated by induced hypotension
C. is monitored by somatosensory evoked potentials
D. may involve division of the diaphragm
E. typically requires postoperative ventilation for several days
A. false B. true C. true D. true E. false Scoliosis is a lateral curvature of the spine often with a rotational element. The deformity usually arises in late childhood and may be postural or structural. Postural scoliosis arises as a compensatory mechanism for problems outside the spine such as a shortened leg or abnormal pelvic tilt. Structural scoliosis is a fixed deformity and is always accompanied by bony abnormalities. Adolescent idiopathic scoliosis is the most common form, presenting in the 10–15 age groupOperative treatment is indicated for a curvature of over 40. Surgery to the upper thoracic spine is achieved by a modified and extended cervical exposure, mid-thoracic spinal surgery is most easily performed via a thoracotomy. A trans-diaphragmatic approach involving detachment of the diaphragm is required for lower thoracic procedures. The degree of risk of spinal cord damage depends on the extent of the vertebral disease and the extent of the reconstruction required. Blood pressure control is important; balancing the need to ensure spinal cord perfusion with the desire to produce a bloodless field. Sodium nitroprusside and esmolol infusions have been widely used for this purpose. Neurophysiological monitoring using spontaneous evoked potentials (SEPs) provides a continuous picture. The electrical stimuli are applied to the lower limbs and appropriate placed electrodes can record cortical (SCEP) or spinal (SSEP) evoked potentials.
42
39. In a 2-week-old term infant with pyloric stenosis and
dehydration the appropriate fluids to be given iv are:
A. 5% dextrose with 0.45% saline
B. 8.4% sodium bicarbonate
C. potassium chloride
D. calcium gluconate
E. Ringer’s lactate
39. A. true B. false C. false D. false E. false Initial treatment depends on the degree of dehydration. For severe dehydration 15% loss of body weight with severe alkalaemia and impending circulatory failure. • Correct the deficit with a bolus of 20ml/kg crystalloid 0.9% saline or colloid For mild to moderate dehydration 5 to 10% loss of body weight with moderate alkalaemia (bicarbonate 32 to 42mmol/l) • Give glucose saline plus 10mmol of KCl per 100ml at 6 to 8ml/kg/h. Plus nasogastric losses as ml of saline Target for fluid therapy: • Serum chloride 106mmol/l • Serum sodium 135mmol/l • Serum bicarbonate 26mmol/l • Urinary chloride 20mmol/l • Urine output 1ml/kg/hMaintenance fluid therapy: Paper 1 Answers 160 • Glucose 4% with saline 0.18% saline. Plus potassium supplements 10mmol KCl per 500ml bag at 4ml/kg/h
43
Cerebral blood flow:
A. is controlled by local variations in metabolic activity
B. is controlled by changes in extracellular pH
C. is affected by changes in PaCO2
D. is 25% of cardiac output
E. in healthy individuals is related to systemic blood pressure
A. true B. true C. true D. false E. false The mean resting cerebral blood flow in young adults is about 50ml/100g brain tissue/min. There are however regional differences in blood flow with mean values for grey matter of 870ml/100g brain/min and white matter 20ml/100g brain/min. The brain accounts for 20% of basal oxygen consumption and 25% of basal glucose consumption. Under normal circumstances this is more than adequately met by the 15% of the cardiac output that the brain receives (750ml/min in adults). The physiological determinates of cerebral blood flow and volume are: • Regional metabolism – Increases in local neural activity are accompanied by increases in regional cerebral metabolic rate this is termed flow-metabolism coupling • Cerebral perfusion pressure CPP MAP (ICP CVP), where CPP cerebral perfusion pressure; MAP mean arterial pressure; ICP intracranial pressure; CVP pressure at jugular bulb (usually zero) central venous PaCO2– partial pressure of carbon dioxide in arterial blood PaCO2affects cerebral blood flow through vasodilatation by changing the pH of the extra cellular fluid. Cerebral blood flow varies linearly with PaCO2 in the range between 3.0 and 7.0kPa and declines at both ends of the range. A 3% change in cerebral blood flow occurs for each 0.1kPa change on PaCO2. PaO2 has less influence on cerebral blood flow until PaO2 is less than 8.0kPa. Temperature Cerebral blood flow increases by 5 to 7% for every 1C rise. Hypothermia decreases both CMR and CBF. Autonomic nervous system • Mainly affects the larger cerebral vessels •-1 adrenergic stimulation results in vasodilatation •-2 adrenergic stimulation leads to vasoconstriction
44
A 50-year-old man is admitted following an acute
myocardial infarction. He developed persistent ST
elevation during his stay in hospital. The ST segment
change:
A. is probably insignificant
B. can indicate pericarditis
C. will be due to ?-blockers
D. is associated with a left ventricular aneurysm
E. is treated with digoxin
A. false B. true C. false D. true E. false
Acute myocardial infarction has a mortality of 25%. Over half of the deaths occur within the first hours usually associated with ventricular fibrillation.
The ECG changes After the first few minutes:
• T waves become tall and pointed and upright
• ST segment elevation After the first few hours:
• T waves invert
• The R wave voltage is decreased
• Q waves develop After a few days:
• The ST segment returns to normal After weeks:
• The T waves may return to normal
• Q waves remain
Persistent ST segment elevation may be due to:
• Acute pericarditis
• Acute cor pulmonale
• Hypokalaemia
• Ventricular aneurysm
45
Features of tension pneumothorax include:
A. raised jugular venous pressure (JVP)
B. pulsus paradoxus
C. tracheal deviation towards the lesion
D. loss of cardiac dullness to percussion
E. Cullen’s sign
42. A. true B. true C. false D. true E. false Symptoms of a pneumothorax
• Shortness of breath
• Pleuritic pain
Signs of a pneumothorax
• Inspection and palpation – decreased expansion
• Percussion – increased percussion note
• Auscultation – decreased breath sounds and decreased SaO2 Tension pneumothorax As above plus:
• Contralateral mediastinal shift
• Cardiovascular collapse
46
The knee jerk:
A. is due to stretch of tendon reflexes
B. is propagated via S1, S2 and S3 nerve roots
C. involves the femoral nerves
D. is instantly abolished following spinal cord trauma
E. is exaggerated following cervical cord trauma
A. false B. false C. true D. true E. true
The knee jerk is a monosynaptic stretch reflex. Stimulus tap the patellar tendon stretches the quadriceps muscle. The sense organ is the muscle spindle.
Afferent fast sensory fibres – type Ia Centrally, the nerves enter the dorsal horn of the spinal cord and synapse with the cell bodies of the motor neurones. Efferent
@-neurones supply the muscle. Response contraction of the quadriceps
47
Premature neonates:
A. are prone to develop hypocalcaemia
B. are sensitive to non-depolarising muscle relaxant drugs
C. have reduced insensible water loss
D. have increased plasma unconjugated bilirubin levels
E. have excess type 1 (oxidative) muscle fibres in the diaphragm
A. true B. true C. false D. true E. false
The risks are such that no child less than 60 weeks should undergo surgery unless absolutely essential. The risks are related to apnoeic spells, which may occur as late as 12h following surgery in about 20 to 30% of healthy neonates. Prolonged observation is necessary and respiratory stimulants may be required. The risks of apnoea decrease with increasing gestational age and local anaesthetic techniques may also reduce the risk of this complication. Other risks include bradycardias, hypothermia and hypoglycaemia. Premature babies should have their maturity assessed from 40 weeks gestation not from the time of the birth.
48
In assessing the adequacy of medullary perfusion during
posterior fossa surgery the appearance of the following
are useful:
A. irregularities in perfusion
B. cardiac arrhythmias
C. hypothermia
D. increase in mean arterial pressure
E. ?waves in the electroencephalogram
45. A. true B. true C. false D. true E. false The pattern of spontaneous respiration has been used to indicate brainstem integrity but the improved surgical fields obtained with IPPV are striking. In the paralysed patient, proximity to the vital structures is indicated by dramatic changes in pulse, cardiac rhythm and blood pressure.
49
Tramadol hydrochloride:
A. produces mydriasis
B. has an anti-nociceptive action that is fully blocked by
naloxone
C. has a greater affinity for ?-receptors than morphine
D. has a peripheral site of action
E. acts to reduce the synaptic concentration of serotonin and
noradrenaline
A. true B. false C. false D. false E. false Tramadol is an opioid analgesic drug introduced into the UK in 1994 but used in other countries for years before.
It is a weak -agonist with even weaker activity at the and subtypes of opioid receptor.
It inhibits the neuronal uptake and promotes the release of both norepinephrine (noradrenaline) and 5-hydroxytryptamine.
It undergoes renal excretion and metabolism. Half-life 6h. Side effects include:
• Nausea and vomiting
• Dry mouth
• Dizziness
• Confusion
• Hallucinations
• Sweating
• Convulsions It appears to produce minimal tolerance and dependence and relatively little respiratory depression
50
The following are nephrotoxic:
A. aminoglycosides
B. isoflurane
C. non-steroidal anti-inflammatory drugs (NSAIDs)
D. angiotensin converting enzyme inhibitor
E. radiocontrast agents
47. A. true B. false C. true D. true E. true NSAIDs inhibit the synthesis of renal prostaglandins that would normally vasodilator the afferent arterioles in the presence of low renal blood flow. NSAIDs may cause acute renal failure. These drugs are contraindicated in patients with impending renal failure. ACE inhibitors reduce the production of angiotensin-2 that normally constricts the efferent arterioles and are also contraindicated. Aminoglycosides cause nephrotoxicity in a dose related manner, which is greater in the elderly
51
During intermittent positive pressure mechanical
ventilation:
A. an increase in peak airway pressure indicates an increase in
total lung compliance
B. a rise in plateau pressure indicates a fall in total lung and
chest wall complianceC. a falling peak pressure can indicate a leak in the breathing
circuit
D. a pneumothorax will produce an increase in peak and
plateau pressures
E. bronchial constriction may be shown by a rise in peak airway
pressure
A. false B. true C. true D. true E. true
52
Intraoperative signs of a haemolytic transfusion reaction
include:
A. hypertension
B. pyrexia
C. urticaria
D. an increase in capillary bleeding
E. periorbital oedema
49. A. false B. true C. false D. true E. true Acute haemolytic transfusion reaction is usually due to an ABO, Lewis, Kell or Duffy incompatible transfusion. IgM complementmediated cytotoxicity or IgG mediated lysis of red cells results in liberation of anaphylotoxins, histamine and coagulation activation. Intra-operative signs include: • Fever • Cyanosis • Bronchospasm • Pulmonary oedema • Cardiovascular collapse and oozing Treatment depends on support for organ failure.
53
Characteristic features of the myasthenic syndrome
include:
A. increase sensitivity to depolarising neuromuscular blocking
drugs
B. decreased eletromyogram (EMG) voltage
C. resistance to non-depolarising neuromuscular blocking
drugs
D. post tetanic facilitation
E. fade of the EMG
A. false B. true C. false D. true E. false Myasthenia syndrome is a non-metastatic manifestation of carcinoma of the lung. Also known as Eaton Lambert syndrome (ELS){definitelynot}.
It is characterised by proximal muscle weakness that typically affects the lower extremities. It is more commonly associated with small cell lung carcinoma. At the molecular level there is a pre-junctional defect in the quantal release of acetylcholine which may be due to antibodies directed against calcium channels.
Clinically Eaton Lambert syndrome produces autonomic effects – hypotension, gastroparesis, urinary retention. Exercise causes an improvement in the weakness. Anticholinesterases do not cause an improvement in the myasthenic syndrome but they do improve myasthenia gravis. Guanide hydrochloride and 4-aminopyridine often help by enhancing acetylcholine release by acting on calcium and potassium channels. The response of patients with the myasthenic syndrome to neuromuscular blocking drugs is sensitive to both depolarising and non-depolarising muscle relaxants. The EMG is characterised by no fade, decreased voltage and the response is improved by repetitive stimulation.
54
Phaeochromocytomas:
A. are noradrenaline secreting tumours
B. can occur anywhere along the sympathetic chain
C. are usually benign
D. produce hypotension
E. produce excessive amounts of adrenaline
51. A. true B. true C. true D. false E. true Phaeochromocytoma is a tumour of chromaffin cells of neuroectodermal origin. 10% bilateral, 10% malignant, 10% extra-adrenal
Secretes norepinephrine and epinephrine. Associated with neurofibromatosis, medullary thyroid carcinoma and multiple endocrine neoplasia-2 (MEN-2). Symptoms • Crisis (17% of cases) headache, sweating, palpitations, hypertension. Sustained in 65%, orthostatic hypotension • Cardiac symptoms, mild hyperglycaemia, elevated haematocrit
55
haemophilia:
A. purpura is rare
B. the bleeding time is prolonged
C. the coagulation time is prolonged
D. the capillary resistant test is normal
E. the clot retraction is normal
52. A. false B. true C. true D. false E. true Haemophilia A – sex linked, recessive, inherited condition with reduced levels of factor VIII. Males are affected while females are carriers. Symptoms – spontaneous bleeding, mostly in joints developing into ankylosis and permanent joint deformities. Coagulation tests: • Prolonged partial thromboplastin time (APTT) the intrinsic pathway • Normal whole blood clotting, normal bleeding time • Diagnosis by assay of factor VIII: C assay • Haemophiliacs treated with sterilised freeze-dried factor VIII. Those treated before this preparation are at risk from hepatitis B and C and HIV Mild haemophiliacs may manage with an infusion of iv desmopressin. Haemophilia B (Christmas disease) is a sex linked recessive inherited condition with reduced levels of factor IX. Coagulation test results are similar to haemophilia A with a reduced factor IX assay. Treatment is with factor IX. Desmopressin is not effective.
56
Circulatory changes during the administration of
enflurane includes decrease in the:
A. systemic vascular resistance
B. right atrial pressure
C. cerebral blood flow
D. renal blood flow
E. splanchnic blood flow
A. true B. true C. false D. true E. true The effects of enflurane include: CNS • Anaesthesia • Minimal analgesia • Epileptogenic and excitatory muscular effect • Increased cerebral blood flow and thus an increase in intracranial pressureCVS Paper 1 Answers 166 • Negative ionotrope • Small decrease in systematic vascular resistance • Mild reflex tachycardia • Coronary vasodilatation • Increased rate of phase 4 depolarisation • Slight myocardial sensitisation to catecholamines Respiratory System • Dose dependent respiratory depression, which is predominantly a reduction in tidal volume • Increase or decrease in respiratory rate • Bronchodilator, non irritant, no increase in secretions Others • Muscle relaxants potentiated • Blood pressure dependent decrease in splanchnic circulation • Decreased renal blood flow and glomerular filtration rate • Decreased uterine tone in pregnancy
57
Atropine:
A. blocks the muscarinic effects of acetylcholine
B. given as a premedication is contraindicated in glaucoma
C. crosses the blood brain barrier
D. inhibits acetylcholine release
E. can cause pyrexia
54. A. true B. false C. true D. false E. true Atropine sulphate is a racemic mixture but only L atropine is active. Atropine combines reversibly with muscarinic cholinergic receptors and thus prevents access of acetylcholine to these sites. It is a competitive antagonist, which means that the effect of the atropine can be overcome by increasing the concentration of acetylcholine in the area of the muscarinic receptors. Atropine does not result in cell membrane changes and associated inhibition of adenylcyclase or alterations in calcium ion permeability that would lead to a cholinergic response. It does not prevent the liberation of acetylcholine and does not react with acetylcholine. Effects include: CVS • Tachycardia but may cause initial bradycardia thought to be due to a central vagal stimulation • Cutaneous vasodilatation CNS • Excitement, hallucinations, hyperthermia especially in children, anti-Parkinsonism effect
RS • Bronchodilatation and increased dead space, reduced secretions GIT • Reduced salivation • Reduced motility • Reduced secretions • Reduced lower oesophageal sphincter tone Others • Mydriasis and cycloplegia • Reduced sweating • Reduced bladder and uterine tone Contraindications Beware glaucoma, hyperpyrexia in children, central anticholinergic syndrome.
58
The following statements are correct:
A. Main stream capnographs significantly increase dead space
B. Side stream capnographs are suitable for use with nasal
cannulae
C. Side stream capnographs under read
D. The response time of side stream capnographs is more rapid
than main stream capnographs
E. End-tidal carbon dioxide concentration reflects changes in
cardiac output
A. false B. true C. true D. false E. true Carbon dioxide analysers are based on the principle that all molecules made up of two or more dissimilar atoms will absorb infrared light. Based on the Beer-Lambert Law. The gas to be analysed can be sampled in two ways. Sidestream The gas is drawn off continuously, usually at about 100 to 150ml/min from the breathing circuit into a detector chamber. For accuracy the tubing supplied should be used. The sampled gas should be returned to the breathing circuit to prevent a leak and waste. This allows lower flows to be used. Advantages • Lightweight connectors to the breathing circuit • Multi-analysis is possible via the same tube Disadvantages • The lag time for the sample leaving the circuit to the monitor is longer • Water vapour contamination if an HMEF is not used, mixing of fresh gas flow with expired gas can occur in the sample tubingMainstream Paper 1 Answers 168 The gas to be analysed does not leave the patient circuit. A detector is placed in the gas flowing in the circuit. This technique can be used with a fuel cell for oxygen or an infrared radiation detector for carbon dioxide. Advantages • Immediate reading • No water vapour contamination • No gas lost from the circuit Disadvantages • Bulky attachment at patient end of circuit, only one gas can be measured at a time. Need a clean window to prevent erroneous readings
59
Inaccurate interpretation of left ventricular end-diastolic
pressure by pulmonary arterial occlusion wedge pressure
measurements occurs in:
A. tricuspid regurgitation
B. aortic regurgitation
C. pulmonary hypertension
D. mitral stenosis
E. mitral incompetence
56. A. false B. true C. false D. true E. false The pulmonary artery capillary occlusion pressure is a reliable indication of left atrial and left ventricular end diastolic pressure. Normal occlusion pressure is 8–12mmHg. It is measured by inflating a balloon at the distal end of a catheter, which is passed into the pulmonary artery. The catheter tip floats into a branch of the pulmonary artery where it wedges. An increase in wedge pressure indicates either a high left ventricular pressure or a high left atrial pressure due to: • Ventricular failure • Fluid overload • Cardiac tamponade • Mitral stenosis Capillary wedge pressure will overestimate left ventricular end diastolic pressure (LVEDP) in: • Increased pulmonary blood flow • Tachycardia, which limits left atrial emptying • Placement of the pulmonary catheter in West zone I where it measures alveolar rather than pulmonary pressure • PEEP • Mitral valve disease, which increases left atrial, pressure The wedge pressure will underestimate left ventricle end diastolic pressure in: • Aortic stenosis • Aortic regurgitation• Ischaemic heart disease due to stiff ventricles • Dilated cardiomyopathy (compliant ventricles
60
Likely causes of a mixed venous hypoxaemia in a
hypothermic patient include:
A. failure to correct the value for body temperature
B. undetected left to right cardiac shuntC. increased oxygen consumption from shivering
D. increased oxygen dissolved in plasma
E. low cardiac output
48. A. true B. false C. true D. true E. true Normal mixed venous oxygen saturation is approximately 75%. It reflects the amount of oxygen left after perfusion of the capillary beds in the systemic circulation. It is decreased when oxygen delivery to the tissues is inadequate for tissue needs (supply exceeds demand) in: • Reduced arterial oxygen content • Reduced cardiac output • Increase in oxygen uptake (rise in VO2) The most common causes are: • Low cardiac output • Anaemia Mixed venous oxygen saturation (SVO2) is increased with: • Sepsis • Cyanide poisoning • Left to right shunt • Hypothermia • A wedged PA flotation catheter
61
Diamorphine:
A. is a naturally occurring opioid
B. is more lipid soluble than morphine
C. has a higher affinity than morphine for opioid receptors
D. is well absorbed after subcutaneous administration
E. is converted to mono-acetyl morphine
A. true B. true C. false D. false E. true Diamorphine is diacetylmorphine. The two acetyl molecules make it more water soluble and give it a faster onset of action and greater fat solubility, so it is better fixed in the spinal cord than morphine. Its metabolism is the same as morphine once the acetyl molecules are removed. It will give rise to M3G and M6G. Comparable doses. Diamorphine 10mg iv is equal to 10mg morphine iv in the body but is often considered more potent because of the quicker speed of onset. Morphine 10mg is equivalent to 5mg oxycodone, 1.5mg hydromorphone and 100g of fentanyl. Equivalence of dose can vary with the route of administration and any first pass effect when given orally, or absorption if used transdermally
62
Mivacurium:
A. penetrates the blood-brain barrier
B. is antagonised by magnesium ions
C. blocks autonomic ganglia
D. is a bisquarternary benzylisoquinoline
E. has an active breakdown product
57. A. true B. false C. false D. true E. false Mivacurium is a short acting, non-depolarising muscle relaxant metabolised by pseudocholinesterase. The amount of histamine released depends on the speed of injection, displacing histamine from the mast cells
63
The following are true of the ideal intravascular pressure
monitoring system:
A. the resonance frequency should be less than 40 Hz
B. the manometer tubing should be compliant
C. the transducer diaphragm should be stiff
D. the damping coefficient is 0.7
E. the manometer tubing should be a small diameter
64
Isoflurane vapour:
A. concentration can be measured using a refractometer
B. is less dense than nitrous oxide
C. will absorb ultraviolet radiation
D. concentration can be measured by absorption of infrared
radiation
E. concentration can be measured by the changes in the
elasticity of silicon rubber
61. A. true B. false C. true D. true E. true There are various techniques for measuring anaesthetic vapours. Infrared analysis for any molecule that is made up of two or more dissimilar atoms. • Ultraviolet for halothane • Interferometer • Piezoelectric effect • Gas chromatography • Mass spectrometry • Photo acoustic method • Thermal conductivity The molecular weight of isoflurane is 184, which is denser than nitrous oxide, which has a molecular weight of 44.
65
Applications of the Doppler effect in the measurement
of blood flow involves changes in:
A. electrical conductivity of a moving stream of blood
B. frequency response on the arterial wallC. frequency reflected ultrasound waves
D. temperate of blood as it moves peripherally
E. harmonic waves of reflected arterial pulses
62. A. false B. true C. true D. false E. false The Doppler effect is the change in the pitch of sound emitted from a rapidly moving vehicle as it passes the observer. Varioususes are made of the Doppler effect in medicine. One application is the ultrasound blood flow detector. In this device ultrasound waves from a vibrating crystal transmitter are beamed along an artery and the red blood cells reflect the high frequency sound waves. A receiving transducer incorporated into the pencil-like probe detects the reflected sound waves and because of the movement of the red cells these reflected sound waves have a Doppler change in frequency. This change in frequency is sensed electronically and is related to the velocity of the blood cells.
66
The air in the operating theatre:
A. has a dew point of 37?C
B. is tested for pollution with anaesthetic gases by means
of an infrared analyser
C. is used in the calibration of an oxygen analyser
D. has a higher pO2 when the temperature is raised
E. contains more oxygen per ml than does arterial blood
for a normal subject
A. false B. false C. true D. false E. false Airflows to operating theatre should have the following characteristics: • Pressure gradient about 35Pa • Air changes 20–40 times per hour • Air flow 45 to 60m3/min • Velocity 3 to 12m/min • Temperature 21–24C • Humidity about 50%
67
The treatment of amitriptyline poisoning includes:
A. forced diuresis
B. an isoprenaline infusion
C. digitalisation
D. intravenous atropine sulphate
E. ?adrenoceptor antagonists
64. A. false B. false C. false D. false E. true The features of tricyclic antidepressant overdose include: Cardiovascular • Sinus tachycardia • Dose related prolongation of the QT interval and widening of the QRS complex, ventricular arrhythmias when the QRS complex is longer than 0.18s • Right bundle branch block • Hypotension or hypertension Central effects • Excitation • Seizures • Depression • Mydriasis • Hyperthermia Anticholinergic Treatment – Treatment includes gastric lavage followed by activated charcoal within 1h of ingestion.Seizures – a benzodiazepine. Ventricular arrhythmias – phenytoin or lidocaine. Inotropes should be avoided where possible as they may precipitate arrhythmias. Intravascular volume expansion is usually sufficient to correct the hypotension. Anticholinergic effects can be reversed by an anticholinesterases but this is not recommended as it may precipitate seizures, bradycardia and heart failure.
68
Gas chromatography:
A. utilises the principle of selectively retarding the passage of
gases through a tube
B. is used to detect enflurane
C. quantifies the individual components of a mixture of
gases
D. uses carbon dioxide as a carrier gas
E. is suitable for measuring nitrous oxide concentrations
65. A. true B. true C. false D. false E. false Gas chromatography is used as a general term for the analytical procedure that separates a mixture into its component parts as the mixture passes through a column. The system has a stationary phase and a mobile phase. The stationary phase is a column of fine silica aluminium coated with polyethylene glycol or silicone. Through this column a flow of carrier gas is passed such as argon or helium. This is the second or liquid phase. Sample gases are then entered into the stream and the speed with which they pass through the column is determined by their differential solubility between the two phases. As the solubility is temperate dependant the apparatus is maintained at a constant temperature. This system is often termed as gas or liquid chromatograph. As the gases leave the column they pass through a detector which may be a: • Flame ionisation detector for organic vapour • Thermal conductivity detector for inorganic vapour • Electron capture detector for a halogenated vapour None of these detectors allows an absolute identification of the component gases and some knowledge of the substance prior or analysis is necessary. All assays need calibration with known concentrations of each particular gas.
69
In cardiac output measurement by thermal dilution:
A. the thermistor is accurate to 1?C
B. measurements under-read cardiac output after 48 h
in situ
C. the thermistor measures true core temperature
D. the measurements under-read cardiac output during
inspiration
E. the thermistor lead is situated proximal to the balloon
A. false B. false C. true D. false E. true The measurement of cardiac output using thermodilution and heat as a detectable indicator in the blood has a number ofadvantages. Heat is rapidly dissipated into the tissues and there is no recirculation time or elevation of the indicator base line. Using a pulmonary artery catheter a 10ml bolus of saline, which used to be cold but is now at room temperature, is injected into the right atrium. The ensuing temperature change is recorded by a thermistor at the catheter tip located in the pulmonary artery. A plot of temperature against time gives a wash out curve from which cardiac output can be calculated using a modification of the Stewart-Hamilton conservation of heat equation. In current practice a microprocessor system measures the area under the curve and calculates cardiac output. Sources of error • Any circumstances that affect the temperature versus time graph– Intracardiac shunts– Severe tricuspid regurgitation or mitral regurgitation • The presence of thrombus on the thermistor can delay cooling and rewarming • The volume, temperature and rate of delivery of injectate • Ventricular arrhythmias • Distal migration of the catheter can lead to disproportionate blood flow with variability in the volume of cold bolus reaching the thermistor
70
67. A direct indication of scatter in a group of experimental
results is provided by:
A. the mean
B. centiles
C. the standard deviation
D. P ?0.05
E. the square of the standard error
A. false B. true C. true D. false E. false The measures of dispersion (measures of variation, scatter and spread) are: • Sample range– The difference between the highest and the lowest values • Percentile– The level of measurement below or above which a specific proportion of the distribution falls • Variance and standard deviation– These measure the spread of observations about the mean– Variance sum of (individual observations mean)2 divided by the number of observations– Standard deviation root of the variance • Coefficient of variation– This is the ratio of the SD of a series of observations to the mean of the observations expressed as a percentage. Coefficient of variation SD/mean 100%
71
Characteristic findings in acute respiratory failure
associated with chronic bronchitis include:
A. a raised jugular venous pressure
B. muscular twitching
C. papilloedema
D. a small volume pulse
E. cold extremities
A. true B. true C. true D. false E. false Type 2 respiratory failure (called “blue bloaters”) is associated with oedema, cyanosis, hypoventilation and a reduced respiratory effort. The patients are hypercapnoeic, giving rise to the following physical findings: • Peripheral vasodilatation • A pounding pulse • A coarse flapping tremor of the out-stretched hands More severe hypercapnoea leads to confusion, drowsiness and coma with papilloedema.
72
Pulmonary hypertension is a complication of:
A. atrial septal defect
B. ventricular septal defect
C. patent ductus arteriosus
D. pulmonary embolism
E. sodium nitroprusside therapy
69. A. true B. true C. true D. true E. false An elevated pulmonary artery pressure know as pulmonary hypertension can be caused by: • Chronic lung disease • Increased pulmonary blood flow because of the left to right shunt through a VSD, ASD and PDA • Left ventricular failure • Mitral valve disease • Left atrial tumour or thrombus • Pulmonary veno-occlusive disease • Pulmonary thromboembolic disease
73
The treatment of acute complete heart block includes:
A. iv glucagon
B. transvenous pacing
C. iv isoprenaline
D. atropine
E. digoxin
A. false B. true C. true D. false E. false If found on preoperative examination complete heart block (even if not sustained) should be treated by temporary or permanent transvenous pacing. The heart rate and cardiac output in complete heart block may increase in response to stimulation, but electrical pacing should be started as soon as possible.
74
The carotid sheath contains the:
A. common carotid artery
B. internal jugular vein
C. sympathetic trunk
D. vagus nerve
E. phrenic nerve
71. A. true B. true C. false D. true E. false The carotid sheath contains: • Internal carotid artery • Internal jugular vein • Vagus nerve and the cervical sympathetic chain in its posterior wall
75
Convulsions occur with:
A. penicillin
B. tetracycline
C. phenobarbitone
D. acetazolomide
E. frusemide
. A. true B. false C. false D. false E. false Convulsions may occur with: • Tricyclic antidepressant poisoning • Antihistamines • Phenothiazines • Penicillins • Any general anaesthetic agent Diazepam 10mg is the treatment of choice followed by phenytoin 1g bolus iv over 4h and 100mg every 8h
76
When regional anaesthesia is compared to general
anaesthesia for hip fractures it is associated with:
A. reduced post-operative mortality
B. reduced blood loss
C. reduce risk of DVT
D. reduced hospital stay
E. better immediate postoperative pain relief
A. true B. false C. true D. true E. true A meta-analysis found the advantages of regional anaesthesia compared to general anaesthesia were: • 1 month mortality 6.4% vs 9.4% • Risk of DVT 30.2% vs 46% • Perioperative confusion 12% vs 22.6% • Hypoxia 35% vs 48% • Myocardial infarction 0.9% vs 1.8% The advantages of a general anaesthetic are less hypotension and a shorter operating time. The technique for airway management and ventilation had no impact on the outcome measures. There was no difference in the incidence of pneumonia, urinary retention and PONV or blood transfusion requirement between regional and general anaesthesia.
77
Rate of diffusion of a gas is:
A. proportional to the thickness of the membrane
B. directly proportional to the tension gradient
C. inversely proportional to the square root of the molecular
weight
D. increased as the temperature of the liquid decreases
E. does not depend on the ambient pressure
A. false B. true C. true D. true E. false Factors which affect the rate of diffusion across the cell membrane: • The concentration gradient: Fick’s law states that the rate of diffusion of a substance across unit area is proportional to the concentration gradient • The molecular weight: Graham’s law states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight • Increases with surface area • Increases with lipid solubility • Decreases with electrical charge of particle
78
The prothrombin time is prolonged in:
A. heparin therapy
B. von Willebrand’s disease
C. scurvy
D. thrombocytopenia
E. jaundice
75. A. false B. false C. false D. false E. true Prothrombin time (PT) tests the extrinsic pathway. The PT is measured by adding animal tissue thromboplastin and calcium to the patient’s plasma. Normal value 12–14s. Prolonged PT in factor VIII deficiency, vitamin K deficiency, liver disease, and oral anticoagulant therapy and DIC.
79
Suxamethonium is contraindicated in:
A. dystrophia myotonica
B. neonates
C. congestive heart failure
D. acute intermittent porphyria
E. Parkinson’s disease
77. A. true B. false C. false D. false E. false Suxamethonium is contraindicated in: • Patients with a history of malignant hyperpyrexia • Anaphylaxis to suxamethonium • Myopathies – Duchenne’s and Myotonia dystrophia Suxamethonium is also relatively contraindicated in certain conditions. Suxamethonium increases the serum potassium by 0.2 to 0.4mmol/l due to the fasciculations. In conditions where there is a proliferation of extra-junctional receptors the release of potassium is increased. • Burns – the potassium may rise greatly for 6h to 2 years after the burn • Massive trauma • Severe intra-abdominal infection • Neurological diseases – spinal cord trauma causing recent paralysis. Suxamethonium can be given immediately after the injury but should be avoided from day 10 to day 100 after the injury • Encephalitis • Stroke • Guillain-Barré syndrome • Ruptured cerebral aneurysm • Polyneuropathies • Tetanus
80
The immediate management of hyperthermia due to
severe exercise includes:
A. immediate cooling
B. aspirin
C. sodium bicarbonate
D. chlorpromazine
E. iv crystalloid
. A. true B. false C. false D. false E. true The immediate management of hyperthermia due to exercise includes the following. General measures to cool the body: • Decrease ambient temperature– expose patient– cold air fans– application of cold water– ice packs to extremities– cold iv fluidsTreatment of complications: Paper 1 Answers 178 • Rhabdomyolisis – mannitol and renal failure • Dantrolene for severe cases General ITU measures.
81
The addition of continuous positive airway pressure (CPAP)
into the breathing system causes a reduction in the:
A. FRC
B. static compliance of the lung
C. dynamic compliance of the lung
D. airway conductance
E. work of breathing
A. false B. false C. false D. false E. true Continuous positive airway pressure (CPAP) is an elevation of the base line pressure throughout the respiratory cycle during spontaneous respiration. It can be applied using a facemask, tracheal tube or laryngeal mask and by a ventilator or pressure generating device. The aim is to prevent or reverse airway closure, thus maintaining or increasing FRC and therefore oxygenation. Increasing FRC may place the patient’s lungs on a more favourable point on the compliance curve and thus minimise the work of breathing. CPAP is maintained at a pre-set level during inspiration and expiration. During ventilatory CPAP inspiratory flow is made available in proportion to the patient’s inspiratory effort but only to maintain the required CPAP level. If the demand valve is slow to respond or the patient has an excessive respiratory drive, flow delivery may be inadequate initially leading to a drop in the CPAP level and increased respiratory work. For breathing circuits sufficient flow must be provided throughout the respiratory cycle so that the patient’s demands are always met. CPAP reduces the work of inspiration and expiration is largely passive.
82
Decompression sickness:
A. is associated with a vascular necrosis of bone
B. is due to an alveolar oxygen deficit
C. is cured by breathing in a mixture of oxygen and helium
D. can occur four hours after the initial drop in pressure
E. is avoided if nitrogen is included in the inspired gas mixture
. A. true B. false C. false D. true E. false During a dive, the ambient pressure causes nitrogen to dissolve into the tissues. On ascent the decrease in pressure causes the nitrogen that has been dissolved in the body tissues to come out of solution. If ascent is too rapid the partial pressure of nitrogen in the tissues will rise above tissue hydrostatic pressure and gas bubbles form. Symptoms range from pains in the tissues around joints (the classical bends) to neurological impairment such as visual disturbances, convulsions, paresis and loss of consciousness. Nitrogen bubbles may also migrate from the tissues into the venous systems to cause a venous gas embolism
83
Patients in diabetic coma can have:
A. lactic acidosis
B. hyperosmolarity
C. ketoacidosis
D. hyperlipidaemia
E. hypocalcaemia
A. true B. true C. true D. true E. false Diabetic coma is usually seen in patients with insulin dependent diabetes mellitus (IDDM) and evolves over a period of one or two days. It is caused by a lack of insulin combined with an increase in glucagon, catecholamine and cortical stimulate lipolysis, free fatty acid production and ketogenesis. Accumulation of keto-acids (-hydroxybutyrate, acetoacetic acid and acetone) results in a metabolic acidosis. Increased gluconeogenesis and glycolysis result in hyperglycaemia which is not taken up peripherally because of the lack of insulin. The renal threshold for glucose is exceeded and glucosuria and ketonuria result in the loss of large amounts of water and electrolytes – hypovolaemia follows. Precipitating factors include: • Sepsis • Surgery • Ischemia and myocardial infarction • Non-compliance with insulin and diet Recognition: • Reduced conscious level • Ketone smell on breath • Advanced dehydration • Acidosis with increasing anion gap
84
The following drugs counteract the effect of isoprenaline
on the heart:
A. propranolol
B. atropine
C. diazoxide
D. trimetaphan
E. nifedipine
82. A. true B. false C. false D. false E. false Isoprenaline is a synthetic catecholamine with non-selective -adrenoceptor action. It is predominantly a chronotrope but also has some inotropic action. As the tachycardia is achieved at the expense of increased myocardial oxygen consumption. Propranolol is a non-selective -bblocker without intrinsic sympathomimetic activity. Atropine may cause an initial bradycardia following a small intravenous dose but the main action is a tachycardia. Diazoxide is a vasodilator chemically related to the thiazide diuretics. It causes an increase in heart rate and cardiac output. Trimetaphan is a competitive antagonist to nicotinic ganglionic receptors. It causes a compensatory increase in heart rate (its short action is due to being metabolised by pseudo cholinesterase). Nifedipine is a calcium channel blocker causing a reflex increased in heart rate and contractility
85
Loss of ankle reflexes is associated with:
A. multiple sclerosis
B. taboparesis
C. ataxia
D. bulbar palsy
E. subacute combined degeneration of the cord
83. A. false B. true C. false D. false E. true Ankle reflex The loss of the ankle reflex is a sign of a disorder of the lower motor neurone. The lower motor neurone is the motor pathway from the anterior horn cell (or cranial nerve nucleus) via a peripheral nerve to the motor end plate. Causes of lower motor neuron lesions: • Anterior horn cell – poliomyelitis, motor neurone disease • Spinal root – cervical and lumber root lesions, neuralgic amyotrophy • Peripheral or cranial nerve – nerve trauma, nerve compression, polyneuropathy In multiple sclerosis there is an upper motor neurone lesion with sensory loss.
86
If effective ?-adrenergic blockade were achieved in a
patient one would expect:
A. hypotension
B. orthostatic hypotension
C. miosis
D. cold pale skin
E. bradycardia
84. A. true B. true C. true D. false E. false-adrenergic antagonists (-blockers) prevent the actions of sympathomimetic agents on -adrenoreceptors. Certain -blockers (phentolamine and phenoxybenzamine) are non-specific and inhibit both -1 and -2 receptors while others selectively inhibit-1 receptors (prazosin) or -2 receptors (yohimbine). Effects include: Cardiovascular •-1 blockade results in vasodilatation and hypotension, which may be orthostatic •-2 blockade facilities norepinephrine release leading to tachycardia and arise in cardiac output • Increased blood flow to skin, viscera and mucosa leading to nasal congestion CNS • Marked sedation • MeiosisOthers • Impotence and contact dermatitis
87
The following can occur after dextran infusion:
A. decreased coagulability
B. difficulties with cross matching of blood
C. renal tubular damage
D. rouleaux formation
E. an antigenic reaction
85. A. true B. true C. true D. true E. true Dextrans are polysaccharides derived from bacterial action on sucrose. There are three types classified according to molecular weight (40, 70 and 100kDa). Side effects • Anaphylactic reactions – urticaria, hypotension, bronchospasm • Interference with cross matching • Coagulopathy resulting in increased bleeding time occurs due to an impaired polymerisation and reduced platelet function
88
Aortic stenosis may be caused by:
A. congenital malformation
B. rheumatic fever
C. subacute bacterial endocarditis (SBE)
D. calcified aortic cusps
E. ruptured aortic cusps
6. A. true B. true C. false D. true E. false Aortic stenosis may be associated with: • Calcified congenital bicuspid value • Rheumatic heart disease • Degenerative disease Symptoms • Angina • Dyspnoea • Effort syncope – occurs only with severe stenosis Signs • Slow rising pulse • A non-displaced apex beat • A harsh ejection systolic murmur in the aortic area radiating to the carotids Investigations CXR is often normal. ECG – left atrial and left ventricular hypertrophy, light bundle branch block (LBBB). Diagnosis can be confirmed by echocardiography and/or Doppler cardiography. Valve replacement is required if symptomatic and/or the pressure gradient across the valve is more than 50mmHg
89
The following are effective in attenuating the pressor
response to intubation:
A. intravenous lidocaine
B. calcium antagonists
C. angiotensin-converting enzyme (ACE) inhibitors
D a large dose of an induction agent
E. ?-blockers
87. A. true B. false C. false D. true E. true Several drugs have been used to lessen the pressor response to intubation. Opioids • Fentanyl 3–5g/kg iv • Alfentanyl 20g/kg iv • Remifentanil 1g/kg immediately prior to induction Lidocaine • 1.5mg/kg iv b-blockers • Esmolol 2–5mg/kg iv a and b-blockers • Labetolol 1mg/kg iv Others • Magnesium sulphate and GTN
90
An elevated left hemidiaphragm can be caused by:
A. left phrenic nerve paralysis
B. left lower lobe collapse
C. sinus inversus
D. left pleural effusion
E. left pneumothorax
A. true B. true C. true D. false E. true A pleural effusion needs to be more than 500ml to cause much more than blunting of the costo-phrenic angle. On an erect film it produces a characteristic shadow with a curved upper edge rising into the axilla.
91
The following increase the risk of cauda equina
syndrome (CES):
A. old age
B. the use of epidural adrenaline
C. the lithotomy position
D. the use of barbotage
E. the prone position
A. true B. true C. false D. false E. false Cauda equina syndrome (CES) is a collection of signs and symptoms resulting from compression or ischaemia of the bundle of nerve roots emerging from the end of the spinal cord below the first lumbar vertebra. The classical syndrome is characterised by severe low back pain with bilateral sciatica associated with saddle anaesthesia, urinary retention and bowel dysfunction. Causes • Injury, herniated intervertebral disc • Secondary to surgery, spinal or epidural anaesthesia, spinal manipulation• Tumours, infection, vascular problems, spina bifida, spinal stenosis, later stages of ankylosing spondylitis Red flags Features of serious back disease: • Severe back pain with bilateral or unilateral sciatica occurring for the first time under the age of 20 or over the age of 65 years • Past history of cancer • Bladder or bowel disturbance • Anaesthesia or paraesthesia in the peri-anal region or buttocks • Lower limb weakness • Gait disturbances • Sexual dysfunction
92
DC cardio-version is indicated for:
A. supraventricular tachycardia
B. ventricular tachycardia
C. premature atrial contraction
D. digitalis toxicity
E. premature ventricular contraction
A. true B. true C. false D. false E. false Cardioversion is an effective treatment for some re-entrant tachyarrhythmias, which may produce haemodynamic instability, and myocardial ischaemia and which do not respond to other measures. Indications • Atrial fibrillation • Arial flutter • Supraventricular tachycardia • Ventricular tachycardia The ECG monitoring lead chosen should demonstrate a clear R wave in order to synchronise the discharge away from the T wave and thus reduce the risk of developing ventricular fibrillation. If the arrhythmia does not convert after the first 50J discharge, further shocks are given using an increased energy discharge up to 200J. Despite the use of a synchronised discharge ventricular fibrillation may be produced in the presence of: • Hypokalaemia • Ischaemia • Digitalis intoxication • QT prolongation cause by quinine, TCA and hyperalimentationThere is a risk of embolic phenomena in patient with: Paper 1 Answers 184 • Mitral stenosis and atrial fibrillation of recent onset • A history of embolic phenomena • Prosthetic valve • Congestive heart failure Patients with these conditions should receive prophylactic anticoagulation
