ANSWERS TO MCQ QUESTIONS

Question 1

A. false B. false C. false D. false E. true

Epiglottitis causes a severe systemic upset with fever and drooling, which contrasts with croup where the child may otherwise be well. Croup is seen between six months and three years. Over this age epiglottitis is more likely to be responsible. Cannulation, direct examination and X-rays should not be attempted as laryngospasm may occur. Short term intubation, initially facilitated with sedation but not paralysis, is usually required and the causative organism is Haemophilus; bacterial tracheitis, which is a differential diagnosis, is caused by Staphylococcus.

Reference: Johnston D, Hull D. Essential Paediatrics, 3rd edn. Churchill Livingstone, 1994

Question 2

A. false B. false C. true D. false E. true

The Mallampati system detects only 50% of difficult intubations. Grade 1 allows a full view down to the tip of the uvula, grade 2 the base of the uvula, grade 3 the soft palate only and grade 4 is where the soft palate cannot be seen. The Wilson test is of ability to protrude the mandible below the maxilla, where A is the mandible beyond the maxilla, B is where they can be aligned, and C is where the mandible cannot be brought in line with the maxilla. Neck extension is more important than flexion, and may reveal vertebro-basilar insufficiency in the susceptible.

Reference: Recognition and management of difficult airway problems. Cobley M, Vaughan R. British Journal of Anaesthesia 1992; 68 :90-97. Also Update in Anaesthesia Issue 9.

Question 3

A. false B. true C. true D. false E. true

Acute porphyric attacks are induced by alcohol, diet, pregnancy and in the case of the hepatic forms of the condition by barbiturates and steroids. Induction of d-aminolaevulinic acid synthetase with a deficiency of an enzyme further down the pathway of haem synthesis underlies all forms. Tourniquets, hypoxia and acidosis induce sickle crises not porphyria. Safe anaesthesia includes propofol, vecuronium, opiates and domperidone. Volatiles are probably not safe, and the use of local anaesthetic agents is contentious.

Reference: Harrison et al. Anaesthesia for the porphyric patient. Anaesthesia 1993; 48 :417

Question 4

A. false B. false C. true D. false E. false

The ASA classification does not predict outcome; it indicates preoperative status and suggests the degree of skill required to deal with the case. It is widely used in audit to indicate the severity of disease and in research to standardise patients. The Harvard Minimum Monitoring Standards were developed as a result of escalating malpractice premiums. E indicates emergency, but has a different definition from that used in the Confidential Enquiries into Perioperative Death.

The ASA classes are, briefly:

I: Fit and well II: Mild systemic disease III: Disease restricting activity IV: Severe systemic disease which is a constant threat to life V: Moribund and not expected to survive 24 hours.

Reference: Update in Anaesthesia No 14

Question 5

A. false B. true C. false D. false E. true

Severe cases require intensive care management and frequently require intubation and ventilation. The condition may be insidious in onset, caused by infection, infarction or insufficient insulin. It is characterised by hypovolaemia (osmotic diuresis) and acidosis (ketone body production); large volumes of fluid are needed in resuscitation, but should be dextrose-free until serum glucose has fallen to below 15mmol/l. There is insulin resistance, and the normal daily requirement will be increased by at least 20%. Insulin therapy causes intracellular uptake of potassium and potassium supplementation is always required. Bicarbonate will only be required in extreme cases with severe systemic acidosis, and rarely with a pH over 7.0. Despite initial high plasma sodium levels, these patients are both salt and water depleted. Initial resuscitation should be with normal saline. Half normal saline may be used with caution.

Reference: Update in Anaesthesia No 11

Question 6

A. true B. true C. false D. true E. false

First described for the assessment of head injury, it is now used for all types of coma. It is most usefully broken down into the components of:

● best motor response (1-6)

● best verbal response (1-5)

● eye opening (1-4)

change over time is a more useful guide to progress than is a single measurement. A score of 2 is not possible as 3 is the lowest score.

Reference: Update in Anaesthesia No 6

Question 7

A. false B. false C. true D. false E. false

Especially if preceded by preoxygenation, signs of hypoxia such as desaturation, bradycardia and ECG changes are late warnings. Capnography is the gold standard but careful auscultation is also helpful in confirming correct placement, although it cannot reliably detect oesophageal placement.

Question 8

A. false B. true C. true D. false E. true

The aetiology of shivering remains unknown but is certainly not due to volatile agents. Peroperative cooling and selective transmission of cold sensation because of a differential neural block are possible contributing factors. A small dose of pethidine may abolish it. Doxapram has also been used. Basal metabolic rate can increase 10-fold and hypoxia is common due to increased oxygen requirements for heat production.

Reference: Crossley AWA. Anaesthesia 1992; 47 :193

Question 9

A. false B. false C. false D. true E. false

The technique is an anaesthetic technique and regardless of local practice it should be conducted by suitable qualified anaesthetists with appropriate resuscitation facilities available. Prilocaine 0.5%, without preservative or vasoconstrictor, is the only agent used in contemporary practice, bupivacaine being discarded because of toxicity. The tourniquet should be inflated to twice systolic blood pressure. The quality of postoperative analgesia is disappointing. There is a recognised risk of methaemaglobinaemia with doses of prilocaine in excess of 600mg.

Reference: page 000 this issue

Question 10

A. true B. true C. false D. false E. true

Agents which provoke histamine release should be avoided because of risk of provoking bronchospasm which may be life threatening. These include atracurium, thiopentone and tubocurarine. Ketamine will cause bronchodilation, as do volatile anaesthetic agents despite the respiratory irritant effects of isoflurane when used for the induction of anaesthesia. Non steroidals should be used with caution in patients know to have asthma.

Reference: Update in Anaesthesia No 12

Question 11

A. false B. true C. false D. false E. false

Pulmonary embolism is the most common cause of death in the first ten days post op. Massive PE is associated with cardiorespiratory collapse and a high mortality. Small PE may cause very few symptoms.

Pleuritic chest pain, dyspnoea and haemoptysis are the common features. Cyanosis, tachypnoea and tachycardia may also occur. Hypotension is the more common feature associated with obstruction of the pulmonary circulation. Cannon waves are seen in complete heart block and not pulmonary embolic disease. The common ECG finding include signs of right ventricular strain; right axis deviation, right bundle branch block, T wave inversion in the right chest leads. The pathognomic sign is the S1 Q3 T3 pattern. This is rarely seen.

Ref: Yentis, Hirsch and Smith. Anaesthesia A to Z. Butterworth.

Question 12

A. false B. false C. true D. true E. true

The complications of massive blood transfusion can be classified into those that are related to the volume of blood given and those related to the storage of blood:

Volume related:

● Transfusion reactions

● Transmission of infection

● Alloimmunisation

● Immunological disturbance

Storage related:

● Hyperkalaemia

● Acidosis

● Hypothermia

● Citrate toxicity

● Hypocalcaemia

● Platelet and clotting factor deficiency

● Microaggregate formation and acute lung injury

● Reduced oxygen delivery due to reduce 2,3 DPG levels

Reference: Update in Anaesthesia No 14

Question 13

A. false B. false C. true D. false E. true

Anaphylaxis = An exaggerated response to a substance which the subject has previously been sensitized to, associated with the liberation of histamine. Sensitization may have occurred by exposure to a related substance.Histamine release is the hallmark of anaphylaxis but cannot practically be measured. Instead more durable markers of histamine release should be sought. Tryptase is a neutral protease released during mast cell degranulation. It is

normally undetectable in the serum but levels remain elevated for up to 16 hours following anaphylaxis. N-methyl-histamine, the major URINARY metabolite histamine may also be detectable for prolonged periods.Type 1 hypersensitivity reactions involve IgE (50% of thiopentone reactions)Classical complement mediated activation involves IgG or IgMAlternative complement activation does not involve antibodies

Reference: McKinnon & Wildsmith. Histaminoid reactions in Anaesthesia. British Journal of Anaesthesia 1995; 74 :217. Update in Anaesthesia No 12

Question 14

A. false B. true C. true D. true E. true

Anaphylaxis = An exaggerated response to a substance which the subject has previously been sensitized to, associated with the liberation of histamine. Sensitization may have occurred by exposure to a related substance.

● 90% of reactions involve cardiovascular collapse

● 10% involve only cardiovascular collapse as a presenting feature

● 80% get an SVT

● 11% of patients arrest

● 3% get pulmonary oedema

● 50% get bronchospasm

● 3% get only bronchospasm as a presenting feature

● 12% get upper airway oedema

Reference: McKinnon & Wildsmith. Histaminoid reactions in Anaesthesia. British Journal of Anaesthesia 1995; 74 :217. Update in Anaesthesia No 12

Question 15

A. true B. false C. false D. false E. false

An ejection systolic murmer may be due to a valvular lesion or may be functional, innocent, and not related to a structural cardiac lesion. Antibiotic cover is recommended for patients with congenital heart disease or acquired valve disease receiving dental or operative treatment. 2D echocardiography will demonstrate calcification or valvular thickening and LVH secondary to aortic stenosis. Doppler echocardiography works out pressures from the velocity of blood within the heart and can be used to determine gradient across the valve. Values over 50mmHg are considered significant, although a poor left ventricle may contract so weakly against a severely stenosed valve that a large gradient is not achieved. Goldmann noted no increase in peroperative mortality with mitral valve disease but a 13% mortality in patients with important aortic stenosis.

Reference: Kaufman L. Anaesthesia Review 10 (Butterworths). Ch1. Also Update in Anaesthesia No 14

Question 16

A. true B. true C. false D. true E. false

Hypokalaemia (potassium less than 3.6mmol/l) may lead to arrythmias, ST depression, T wave inversion and a prominent U wave on the ECG. Hyponatraemia to the extent of 114mmol/l is abnormal. The serum sodium is frequently 5mmol/l less than normal in hospital patients and is a result of sick cell syndrome. Bronchial carcinoma is associated with inappropriate ADH secretion which can cause severe hyponatraemia. Hypercalcaemia over 2.6mmol/l may lead to a shortened QT interval on ECG as well as other cardiac arrythmias and hypertension. The normal plasma CSF glucose is approximately 65% of the blood glucose. A lower CSF glucose than this, as shown, is indicative of bacterial meningitis. The normal plasma albumin is 35-50g/l. Catabolic states such as severe sepsis, trauma, fever and malignancy lead to hypoalbumenaemia.

Reference: Marshall. Clinical Chemistry. J.B. Lippincott Company.

Question 17

A. true B. false C. true D. false E. false

Human malignant hyperthermia is inherited as an autosomal dominant with links to gene loci on chromosomes 17 and 19. Triggering agents include suxamethonium, (which can produce a very rapid onset) halothane, enflurane, isoflurane, desflurane, sevoflurane, methoxyflurane, ether and cyclopropane. The incidence is approximately 1/15,000 anaesthetics. Mannitol is present in bottles of Dantrolene to make the solution isotonic. Miller suggests that 3-4 people will be needed to get a dose of 2gm/kg into solution for an adult. Even in high dose, dantrolene will only produce mild muscle weakness.

Reference: Miller. Anesthesia. Churchill Livingstone. Chapter 31.

Question 18

A. false B. true C. false D. true E. false

Sickle cell disease is commonest in people originating in west and central afrIca and also from around the mediterranean. Sickle cell trait is present in 10% of African Americans in whom 40% of their Hb is as HbS. Sickle cell anaemia is found in 1% of African Americans and their Hb is very predominantly HbS. On desaturation of their Hb the HbS is 50 times less soluble than HbA and tactoids of rigid Hb chains are formed altering the function of the red blood cells. Haemolytic anaemia occurs along with organ damage due to to vascular obstruction in the spleen, kidneys, gut, and brain. Aplastic crises can occur when the bone marrow fails as a result of intercurrent infection or folate defficiency. Exchange transfusion is appropriate prior to major vascular surgery as O ₂ carriage is increased and the risk of sickling

is decreased. Folate therapy is appropriate as it may help marrow function at a time of additional stress. Esmarch tourniquets have been described as used without problems in some patients although overall the use of tourniquets would be considered contra-indicated.

Reference: Katz J. Anaesthesia and uncommon diseases. Saunders. Sickle cell anaemia. p391-397.

Question 19

A. false B. true C. false D. false E. true

Mitral stenosis is usually the result of rheumatic fever with a distorted and partly fused valve secondarily calcifying. Slow deterioration with dyspnoea, pulmonary oedema, chest pain, palpitations and haemoptysis occurs. Left atrial pressure is chronically raised and pulmonary hypertension occurs. Atrial contraction will contribute 30% of ventricular filling and if atrioventricular pacing is needed a long P-R interval will help filling of the ventricle. Cardiac output will usually not be helped by afterload reduction in the setting of a normal blood pressure since the obstruction is at mitral valve level. Pulmonary vascular resistance is a serious problem with right ventricular failure being a risk. If pulmonary vascular resistance increases the right ventricle may further distend and the inter-ventricular septum intrude on left ventricular function. Due to the pulmonary hypertension the pulmonary diastolic pressure will often be considerably above the pulmonary wedge pressure.

Reference: Hensley. The practice of cardiac anaesthesia. Little, Brown. Anaesthetic management for the treatment of valvular heart disease. Also Update in Anaesthesia No 14

Question 20

A. true B. false C. false D. true E. true

In aortic stenosis the normal aortic valve area decreases from 3cm ² to less than 1cm ² . Without increased left ventricular systolic

pressures the blood flow across the valve is dependent on the pressure gradient. With compensatory hypertrophy of the left ventricle the aortic valve gradient will increase. However later in the disease as the left ventricle dilates and further fails the left ventricular valve gradient will fall as cardiac output falls. A relatively slower heart rate is important to allow adequate time for left ventricular filling and emptying. The increased impedance to left ventricular emptying is at valve level and so changes in systemic vascular resistance will not signicantly affect left ventricular emptying. However a decrease in systemic vascular resistance may lead to critical reductions in myocardial perfusion. Episodes of myocardial ischaemia should be treated by firstly increasing systemic perfusion pressure. Vasodilators such as nitrates should be used with extreme caution if at all.

Reference: Hensley. The practice of cardiac anaesthesia. Little, Brown. Anaesthetic management for the treatment of valvular heart disease.

Also Update in Anaesthesia No 14