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Question 1Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

During direct laryngoscopy, which laryngeal structure forms the anterior attachment of the true vocal cords and is the landmark for identifying the glottic opening?

  1. Cricoid cartilage
  2. Arytenoid cartilage
  3. Anterior commissure Correct answer.
  4. Corniculate cartilage

Explanation

The anterior commissure is the point where the two true vocal cords converge anteriorly, attaching to the inner surface of the thyroid cartilage. It marks the front boundary of the glottic opening and is a key landmark when confirming cord position during intubation. The arytenoids and corniculates sit posteriorly, while the cricoid lies inferior to the glottis.

Question 2Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient with a suspected anterior fossa skull base fracture is being assessed. Which structure perforates the cribriform plate and explains the risk of cerebrospinal fluid rhinorrhoea in this injury?

  1. Olfactory nerve fibres Correct answer.
  2. Greater petrosal nerve
  3. Maxillary division of the trigeminal nerve
  4. Optic nerve

Explanation

Olfactory nerve fibres pass through the perforations of the cribriform plate of the ethmoid bone to reach the olfactory bulb. A fracture here tears the meningeal covering and the nerve filaments, allowing CSF to leak into the nasal cavity. The optic nerve exits via the optic canal, and the maxillary nerve leaves through the foramen rotundum.

Question 3Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which nerve is most at risk of injury during surgical dissection deep to the posterior border of the sternocleidomastoid muscle in the posterior triangle of the neck?

  1. Phrenic nerve
  2. Spinal accessory nerve Correct answer.
  3. Hypoglossal nerve
  4. Recurrent laryngeal nerve

Explanation

The spinal accessory nerve (cranial nerve XI) emerges from behind the sternocleidomastoid and crosses the posterior triangle superficially to the levator scapulae. It is vulnerable during lymph node biopsy or deep dissection in this region, and injury causes shoulder droop and weakness of trapezius. The phrenic nerve lies deeper on the anterior scalene, and the hypoglossal and recurrent laryngeal nerves are in the anterior neck.

Question 4Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient sustains a fracture of the surgical neck of the humerus. Which nerve is most commonly injured, and which movement would be most affected?

  1. Radial nerve; wrist extension
  2. Axillary nerve; shoulder abduction Correct answer.
  3. Musculocutaneous nerve; elbow flexion
  4. Median nerve; thumb opposition

Explanation

The axillary nerve winds around the surgical neck of the humerus together with the posterior circumflex humeral artery. Injury paralyses the deltoid and teres minor, weakening shoulder abduction and causing numbness over the deltoid region. The radial nerve is more typically injured with mid-shaft humeral fractures in the spiral groove.

Question 5Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement correctly describes the functional difference between the conduction system of the heart and typical atrial myocardium?

  1. Conduction fibres contract more forcefully than atrial muscle
  2. Conduction fibres lack gap junctions and rely on chemical synapses
  3. Conduction fibres depolarise spontaneously because of unstable resting potential Correct answer.
  4. Conduction fibres are richly supplied by vagal parasympathetic endings

Explanation

Pacemaker cells of the sinoatrial and atrioventricular nodes show spontaneous phase 4 depolarisation due to funny current and calcium influx, giving an unstable resting membrane potential. Typical atrial myocytes maintain a stable resting potential and require an external stimulus. Both tissue types are electrically coupled through gap junctions rather than chemical synapses.

Question 6Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

During inspiration at rest, which change in intrathoracic pressure and lung volume is correct?

  1. Intrapleural pressure becomes more negative and lung volume decreases
  2. Intrapleural pressure remains unchanged while lung volume increases
  3. Intrapleural pressure becomes more negative and lung volume increases Correct answer.
  4. Intrapleural pressure becomes more positive and lung volume decreases

Explanation

Contraction of the diaphragm and external intercostals enlarges the thoracic cavity, so intrapleural pressure falls from about -5 to -8 cmH2O relative to atmosphere. The resulting transpulmonary pressure gradient expands the lungs and increases lung volume. A more positive intrapleural pressure would oppose lung expansion.

Question 7Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient breathing room air has an arterial partial pressure of oxygen of 60 mmHg and a haemoglobin concentration of 150 g/L. Using the standard oxyhaemoglobin dissociation curve, what is the approximate arterial oxygen saturation?

  1. 90% Correct answer.
  2. 75%
  3. 97%
  4. 100%

Explanation

On the standard curve, a PaO2 of 60 mmHg corresponds to approximately 90% saturation, which is the point used to define type 1 respiratory failure. Saturation rises steeply above this value, reaching about 97% at a PaO2 of 100 mmHg. The flat upper portion explains why supplemental oxygen produces little additional content once saturation is near normal.

Question 8Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which receptor type is responsible for the rapid transmission of sharp, well-localised pain from the skin?

  1. Pacinian corpuscles
  2. C polymodal nociceptors
  3. Ruffini endings
  4. A-delta mechanonociceptors Correct answer.

Explanation

A-delta fibres are thinly myelinated and conduct at roughly 5 to 30 m/s, producing the fast, sharp first pain that is well localised. C fibres are unmyelinated, conduct slowly, and mediate dull, poorly localised second pain. Pacinian corpuscles and Ruffini endings are low-threshold mechanoreceptors, not nociceptors.

Question 9Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A drug has a volume of distribution of 40 litres in a 70 kg adult. Which interpretation is most appropriate?

  1. The drug is poorly absorbed from the gut
  2. The drug is heavily bound to plasma proteins
  3. The drug is largely confined to plasma
  4. The drug is extensively distributed to tissue Correct answer.

Explanation

A volume of distribution of about 0.57 L/kg exceeds total body water (roughly 0.6 L/kg only marginally) and indicates substantial distribution out of plasma into tissues. Plasma volume alone is about 3 litres, so values near that suggest plasma confinement. Volume of distribution does not directly measure protein binding or absorption.

Question 10Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the mechanism of action of beta-blockers such as metoprolol is correct?

  1. They block L-type calcium channels in vascular smooth muscle
  2. They inhibit the sodium-potassium ATPase pump
  3. They inhibit angiotensin-converting enzyme
  4. They competitively antagonise beta-adrenergic receptors Correct answer.

Explanation

Beta-blockers bind beta-adrenergic receptors reversibly and prevent catecholamine-mediated increases in heart rate and contractility. This reduces myocardial oxygen demand and is useful in ischaemic heart disease and arrhythmia control. Calcium channel blockers and ACE inhibitors act by unrelated mechanisms.

Question 11Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient receiving a competitive neuromuscular blocking agent develops prolonged paralysis. Which pharmacological principle best explains reversal with a cholinesterase inhibitor such as neostigmine?

  1. It increases acetylcholine at the motor end plate, outcompeting the blocker Correct answer.
  2. It directly displaces the blocker from the receptor binding site
  3. It reduces acetylcholine release from the presynaptic terminal
  4. It increases acetylcholinesterase activity at the junction

Explanation

Neostigmine inhibits acetylcholinesterase, so acetylcholine accumulates in the synaptic cleft and competes more effectively with the non-depolarising blocker for nicotinic receptors. This shifts the competitive equilibrium toward receptor activation. It does not bind the receptor itself or enhance acetylcholinesterase activity.

Question 12Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which of the following is a recognised adverse effect of prolonged high-dose glucocorticoid therapy?

  1. Osteoporosis Correct answer.
  2. Weight loss
  3. Adrenal hyperplasia
  4. Hyperkalaemia

Explanation

Glucocorticoids reduce bone formation and increase resorption, so prolonged therapy causes osteoporosis and increased fracture risk. They also cause sodium and water retention with hypokalaemia, and they suppress rather than stimulate the adrenal axis. Weight gain, not weight loss, is typical.

Question 13Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient with sepsis is prescribed noradrenaline. Which receptor action primarily accounts for the rise in mean arterial pressure?

  1. Beta-2 mediated bronchodilation
  2. Alpha-1 mediated vasoconstriction Correct answer.
  3. Beta-1 mediated negative inotropy
  4. Muscarinic-mediated bradycardia

Explanation

Noradrenaline acts predominantly on alpha-1 receptors in vascular smooth muscle, causing vasoconstriction and raising systemic vascular resistance. This is the main mechanism by which mean arterial pressure increases in septic shock. Its modest beta-1 activity supports contractility but is not the dominant pressor mechanism.

Question 14Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which inhalational anaesthetic has the lowest blood-gas solubility and therefore the fastest equilibration of alveolar and brain partial pressures?

  1. Sevoflurane
  2. Desflurane Correct answer.
  3. Halothane
  4. Isoflurane

Explanation

Desflurane has a blood-gas partition coefficient of about 0.42, the lowest of the volatile agents in common use, so blood equilibrates rapidly with alveolar gas. This produces the fastest induction and recovery among the volatiles. Halothane has the highest partition coefficient and the slowest kinetics.

Question 15Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A 70 kg patient requires a loading dose of a drug with a volume of distribution of 0.5 L/kg and a target plasma concentration of 4 mg/L. What loading dose is required?

  1. 35 mg
  2. 280 mg
  3. 140 mg Correct answer.
  4. 70 mg

Explanation

Volume of distribution is 0.5 L/kg multiplied by 70 kg, giving 35 litres. The loading dose equals volume of distribution times target concentration, so 35 L times 4 mg/L equals 140 mg. Loading dose depends on distribution rather than on clearance.

Question 16Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the first-pass effect is correct?

  1. It applies only to drugs given intravenously
  2. It increases the oral bioavailability of lipophilic drugs
  3. It reduces the systemic availability of orally administered drugs metabolised in the liver Correct answer.
  4. It describes renal excretion of unchanged drug

Explanation

Orally absorbed drug passes through the portal circulation and is metabolised by the liver before reaching systemic circulation, lowering bioavailability. Drugs with high extraction ratios show a pronounced first-pass effect. Intravenous administration bypasses this pathway entirely.

Question 17Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

In a patient with severe hepatic impairment, which pharmacokinetic change is most likely for a drug that undergoes extensive hepatic metabolism?

  1. Unchanged clearance because renal excretion compensates fully
  2. Increased plasma protein binding with reduced free fraction
  3. Reduced clearance and prolonged half-life Correct answer.
  4. Increased clearance and reduced half-life

Explanation

Hepatic impairment reduces metabolic capacity and liver blood flow, so clearance of a highly extracted drug falls and half-life lengthens. This predisposes to accumulation and toxicity unless the dose is reduced. Renal compensation is incomplete for drugs dependent on hepatic metabolism.

Question 18Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which physical principle explains why a small pneumothorax may be difficult to detect on a supine chest radiograph?

  1. Small air collections produce only subtle differences in transmitted X-ray intensity Correct answer.
  2. Air and soft tissue have similar attenuation coefficients at diagnostic energies
  3. Pleural air increases tissue density and masks the lung edge
  4. X-ray beams are completely absorbed by the thoracic cage

Explanation

Pleural air lowers attenuation only slightly relative to adjacent lung and soft tissue, so the contrast difference is small and a thin rim may be invisible. In supine patients air collects anteriorly, further reducing the visible pleural line. The thoracic cage does not completely absorb the beam.

Question 19Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the Doppler effect as applied to ultrasound blood flow measurement is correct?

  1. The frequency shift is proportional to the cosine of the angle between the beam and flow Correct answer.
  2. The frequency shift is unrelated to blood velocity
  3. The frequency shift increases as the angle approaches 90 degrees
  4. The frequency shift is independent of the transmitted frequency

Explanation

The Doppler shift equals 2 times transmitted frequency times velocity times cosine of the insonation angle divided by the speed of sound in tissue. The cosine term means the measured shift is maximal when the beam is parallel to flow and zero at 90 degrees. Shift also rises with transmitted frequency and with velocity.

Question 20Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which property of a laser beam is most relevant to the risk of retinal injury from a visible-wavelength laser?

  1. Low monochromaticity
  2. High divergence of the beam
  3. Focusing of the beam by the cornea and lens onto the retina Correct answer.
  4. Coherence of the emitted photons

Explanation

The eye focuses a collimated visible laser beam to a small spot on the retina, concentrating energy and causing local thermal damage. This focusing effect is why laser safety requires eye protection and controlled beam paths. Coherence and monochromaticity are defining properties but do not by themselves explain the hazard.

Question 21Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which principle underlies the use of a pulsed oximeter's ability to distinguish arterial from venous and tissue light absorption?

  1. Tissue absorption is constant and therefore subtracted
  2. Infrared light is absorbed equally by all haemoglobin species
  3. Absorption differs between oxygenated and deoxygenated haemoglobin at two wavelengths Correct answer.
  4. Venous blood pulsates more strongly than arterial blood

Explanation

Pulse oximetry compares absorption of red and infrared light, exploiting the different absorption spectra of oxyhaemoglobin and deoxyhaemoglobin. The pulsatile component isolates arterial blood from static tissue and venous signals. Equal absorption across species would make the measurement impossible.

Question 22Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement correctly describes the effect of a high-pass filter on an ECG signal contaminated by baseline wander?

  1. It removes low-frequency drift while preserving the higher-frequency QRS complexes Correct answer.
  2. It amplifies the baseline drift
  3. It removes high-frequency muscle artefact
  4. It eliminates the entire ECG signal

Explanation

A high-pass filter attenuates frequencies below its cutoff, and baseline wander from respiration or movement lies at low frequency. QRS energy is concentrated at higher frequencies, so it passes through largely intact. Low-pass filtering is used to remove high-frequency noise such as muscle artefact.

Question 23Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A cylinder contains oxygen at a gauge pressure of 137 bar and has a water capacity of 10 litres. Using Boyle's law and assuming a full cylinder pressure of 200 bar, approximately what volume of oxygen at atmospheric pressure remains?

  1. 2000 litres
  2. 1370 litres Correct answer.
  3. 137 litres
  4. 685 litres

Explanation

The contents at atmospheric pressure equal gauge pressure times cylinder water capacity, so 137 bar times 10 L gives about 1370 litres. This approximation ignores the small correction for the residual pressure and non-ideal gas behaviour. A full 200 bar cylinder of the same size would hold about 2000 litres.

Question 24Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about laminar flow through an endotracheal tube is correct according to Poiseuille's law?

  1. Flow is proportional to the fourth power of the tube radius Correct answer.
  2. Flow is independent of gas viscosity
  3. Flow increases as tube length increases
  4. Flow is proportional to the square of the pressure gradient

Explanation

Poiseuille's law states that laminar flow varies with the fourth power of radius, directly with the pressure gradient, and inversely with viscosity and length. This steep radius dependence explains why small reductions in tube diameter greatly increase resistance. Turbulent flow follows different relationships.

Question 25Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

During cardiopulmonary bypass, which physiological change most directly reduces the risk of haemolysis in a centrifugal pump?

  1. Increased pressure gradients across the oxygenator
  2. Low shear stress and gentle acceleration of blood Correct answer.
  3. Turbulent flow within the arterial cannula
  4. High shear stress generated at the pump head

Explanation

Centrifugal pumps accelerate blood gently by a rotating impeller, producing lower shear stress than roller pumps and reducing red cell damage. High shear stress and turbulent flow are the principal causes of haemolysis. Pressure gradients across the oxygenator do not directly govern haemolysis in the pump.

Question 26Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

During the cardiac cycle, which event produces the first heart sound (S1)?

  1. Closure of the mitral and tricuspid valves Correct answer.
  2. Closure of the aortic and pulmonary valves
  3. Rapid ventricular filling
  4. Opening of the mitral and tricuspid valves

Explanation

The first heart sound is caused by closure of the atrioventricular valves (mitral and tricuspid) at the onset of ventricular systole, when ventricular pressure exceeds atrial pressure. This prevents backflow into the atria and marks the beginning of isovolumetric contraction.

Question 27Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the physiological dead space is correct?

  1. It equals the tidal volume minus the residual volume
  2. It is the volume of gas that participates in gas exchange
  3. It is the sum of anatomical and alveolar dead space Correct answer.
  4. It increases when pulmonary blood flow increases

Explanation

Physiological dead space is the total volume of lung that does not participate in gas exchange and comprises the anatomical dead space (conducting airways) plus the alveolar dead space (ventilated but unperfused alveoli). It is measured using the Bohr equation.

Question 28Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the mechanism of action of non-depolarising neuromuscular blocking drugs is correct?

  1. They inhibit acetylcholinesterase at the neuromuscular junction
  2. They block voltage-gated sodium channels in the motor nerve terminal
  3. They cause prolonged depolarisation of the motor endplate
  4. They act as competitive antagonists at nicotinic acetylcholine receptors on the motor endplate Correct answer.

Explanation

Non-depolarising neuromuscular blockers competitively antagonise acetylcholine at the postjunctional nicotinic receptor, reducing endplate depolarisation and preventing muscle contraction. Their effect can be partially reversed by increasing acetylcholine concentration with anticholinesterases.

Question 29Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is given an intravenous bolus of a drug that follows first-order elimination. Which statement best describes the plasma concentration-time curve?

  1. The half-life increases as the concentration falls
  2. The clearance decreases as the concentration falls
  3. The concentration falls linearly with time
  4. The concentration falls exponentially with a constant half-life Correct answer.

Explanation

In first-order elimination, a constant fraction of the drug is eliminated per unit time, so plasma concentration declines exponentially and the half-life remains constant regardless of concentration. Clearance is also constant in linear kinetics.

Question 30Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the physiological effects of hypercapnia is correct?

  1. Hypercapnia stimulates peripheral chemoreceptors and increases sympathetic activity Correct answer.
  2. Hypercapnia directly depresses the respiratory centre at all levels
  3. Hypercapnia causes cerebral vasoconstriction and reduces cerebral blood flow
  4. Hypercapnia produces a metabolic alkalosis by increasing bicarbonate reabsorption

Explanation

Raised arterial carbon dioxide stimulates the peripheral chemoreceptors (carotid and aortic bodies) and increases sympathetic outflow, raising heart rate and blood pressure. It also causes cerebral vasodilation and increases cerebral blood flow.

Question 31Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is receiving an infusion of a drug that is eliminated by zero-order kinetics. If the infusion rate is increased, what happens to the time to reach steady state?

  1. It decreases because the infusion rate is higher
  2. It is unpredictable because half-life changes with concentration Correct answer.
  3. It remains unchanged because half-life is constant
  4. It increases because clearance falls as concentration rises

Explanation

In zero-order kinetics, elimination pathways are saturated, so clearance falls as concentration rises and half-life increases with concentration. Consequently, the time to reach steady state is not constant and becomes unpredictable and often prolonged when the infusion rate is increased.

Question 32Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the mechanism of action of ketamine is correct?

  1. It is a non-competitive antagonist at the NMDA receptor Correct answer.
  2. It is a competitive antagonist at the NMDA receptor
  3. It is a GABA-A receptor agonist
  4. It is an opioid receptor agonist

Explanation

Ketamine produces anaesthesia mainly by non-competitive antagonism at the NMDA glutamate receptor, reducing excitatory neurotransmission. This mechanism underlies its dissociative anaesthetic and analgesic properties.

Question 33Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is given a drug that has a high hepatic extraction ratio. Which change is expected if hepatic blood flow decreases?

  1. Half-life decreases because volume of distribution falls
  2. Clearance increases because more drug is metabolised
  3. Clearance remains unchanged because enzyme activity is unaffected
  4. Clearance decreases because clearance is flow-dependent Correct answer.

Explanation

For a drug with a high hepatic extraction ratio, hepatic clearance is approximately equal to hepatic blood flow. Therefore, a fall in hepatic blood flow reduces clearance and prolongs half-life, independent of enzyme activity.

Question 34Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is receiving a drug that is a weak base. In which condition would the fraction of unionised drug available for diffusion across membranes be highest?

  1. In an acidic environment
  2. In an environment containing a strong acid
  3. In an alkaline environment Correct answer.
  4. In a neutral environment

Explanation

Weak bases are less ionised in alkaline environments because the equilibrium shifts toward the unionised form. The unionised form is more lipid-soluble and crosses cell membranes more readily.

Question 35Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is receiving warfarin and is prescribed a drug that inhibits cytochrome P450 enzymes. What is the most likely effect?

  1. Warfarin metabolism is decreased and INR rises Correct answer.
  2. Warfarin metabolism is increased and INR falls
  3. Warfarin absorption is reduced and bioavailability falls
  4. Warfarin protein binding is reduced and free fraction falls

Explanation

Inhibition of cytochrome P450 enzymes reduces the metabolism of warfarin, leading to higher plasma concentrations and an increased INR, with a greater risk of bleeding. Close monitoring and dose adjustment are required.

Question 36Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

Which statement about the physical principles of pulse oximetry is correct?

  1. Oximeters are unaffected by carboxyhaemoglobin
  2. Oximeters measure the partial pressure of oxygen directly
  3. Oximeters measure the ratio of light absorption at two wavelengths to estimate oxygen saturation Correct answer.
  4. Oximeters use the same wavelength for oxyhaemoglobin and deoxyhaemoglobin

Explanation

Pulse oximeters use two wavelengths of light (typically red and infrared) and measure the pulsatile component of absorption to calculate the ratio of oxyhaemoglobin to total haemoglobin. This ratio is then empirically calibrated to arterial oxygen saturation.

Question 37Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is receiving an inhalational anaesthetic. Which factor most increases the risk of delivering a hypoxic mixture when using a nitrous oxide and oxygen blend?

  1. The use of a calibrated vaporiser
  2. The use of a machine with a nitrous oxide cut-off valve
  3. The absence of a nitrous oxide cut-off valve Correct answer.
  4. The presence of a functioning oxygen failure alarm

Explanation

A nitrous oxide cut-off valve prevents delivery of a hypoxic mixture by limiting nitrous oxide flow when oxygen pressure falls. Without this safety device, a hypoxic mixture may be delivered if oxygen supply is interrupted.

Question 38Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is undergoing surgery with a laser. Which statement about laser safety is correct?

  1. The laser beam is most hazardous to the cornea at all wavelengths
  2. The risk of retinal injury is highest with far-infrared lasers
  3. Laser safety eyewear is unnecessary if the patient's eyes are closed
  4. The eye is most vulnerable to wavelengths in the visible and near-infrared range Correct answer.

Explanation

Visible and near-infrared laser light passes through the cornea and lens and is focused onto the retina, making these wavelengths most hazardous to the eye. Far-infrared and ultraviolet lasers are largely absorbed by the cornea and conjunctiva.

Question 39Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is receiving an infusion of a drug with a high therapeutic index. Which statement about monitoring is most appropriate?

  1. The drug should be avoided in all patients with renal impairment
  2. Clinical monitoring is usually sufficient because toxicity is unlikely Correct answer.
  3. The infusion rate must be reduced because of saturation kinetics
  4. Routine plasma concentration monitoring is essential to avoid toxicity

Explanation

A high therapeutic index means the difference between therapeutic and toxic doses is large, so routine plasma concentration monitoring is generally unnecessary; clinical monitoring suffices. Monitoring is more relevant for drugs with a low therapeutic index.

Question 40Basic and Applied Sciences (anatomy, physiology, pharmacology, physics and equipment)

A patient is receiving a drug that is a potent inhibitor of CYP3A4. Which co-administered drug is most likely to accumulate and cause toxicity?

  1. A drug that is primarily metabolised by CYP3A4 Correct answer.
  2. A drug that is a substrate for CYP2D6
  3. A drug that is eliminated unchanged by the kidneys
  4. A drug that has a high hepatic extraction ratio

Explanation

Inhibiting CYP3A4 reduces the metabolism of drugs that are substrates of this enzyme, leading to accumulation and potential toxicity. Drugs eliminated unchanged by the kidney or metabolised by other enzymes are less affected.

Question 41Preanesthetic Assessment and Patient Preparation

A patient scheduled for elective surgery reports a severe sore throat, fever, and productive cough that began two days ago. What is the most appropriate preanesthetic action?

  1. Proceed with anesthesia but switch to regional technique
  2. Give prophylactic antibiotics and proceed as scheduled
  3. Obtain a chest radiograph and proceed if it is normal
  4. Postpone elective surgery and reassess after the acute infection resolves Correct answer.

Explanation

An active upper respiratory tract infection increases the risk of bronchospasm, laryngospasm, and perioperative pulmonary complications, so elective procedures are generally deferred until symptoms resolve. Proceeding with any anesthetic technique during an acute febrile respiratory illness exposes the patient to avoidable risk. Reassessment after resolution is the standard approach.

Question 42Preanesthetic Assessment and Patient Preparation

Which laboratory value is most directly relevant when assessing a patient with chronic kidney disease for a planned general anesthetic?

  1. Serum amylase concentration
  2. Serum potassium concentration Correct answer.
  3. Total white blood cell count
  4. Platelet mean volume

Explanation

Hyperkalemia is a common and dangerous consequence of chronic kidney disease and can precipitate arrhythmias, especially with succinylcholine or potassium-containing fluids. Potassium is therefore a key value to review before induction. The other listed tests do not reflect the primary electrolyte risk in renal failure.

Question 43Preanesthetic Assessment and Patient Preparation

A patient reports an allergy to lidocaine with facial swelling and hives after a dental procedure. Which classification is most accurate?

  1. Local anesthetic allergy confirmed by symptoms
  2. Vasovagal reaction to the injection
  3. Possible allergy requiring further evaluation before neuraxial or regional block Correct answer.
  4. True amide local anesthetic hypersensitivity

Explanation

Hives and facial swelling after local anesthetic exposure suggest a possible immunoglobulin E-mediated reaction, but true local anesthetic allergy is rare and most reactions are psychogenic or vasovagal. The history should prompt allergy evaluation and selection of an agent from a different class before regional techniques. A definitive label of confirmed allergy is premature without testing.

Question 44Preanesthetic Assessment and Patient Preparation

Which finding on the preoperative airway assessment most strongly predicts difficult mask ventilation?

  1. Interincisor distance greater than 5 cm
  2. Thyromental distance greater than 7 cm
  3. Presence of a beard Correct answer.
  4. Mallampati class I

Explanation

Beard, edentulous state, obesity, and age over 55 are recognized predictors of difficult mask ventilation. A beard interferes with a tight mask seal and is a validated independent risk factor. The other listed findings are normal or favorable airway measurements.

Question 45Preanesthetic Assessment and Patient Preparation

A patient with a history of obstructive sleep apnea is scheduled for outpatient surgery. Which preoperative measure most appropriately reduces perioperative risk?

  1. Prescribe a sedative premedication to reduce anxiety
  2. Schedule the procedure as the last case of the day
  3. Discontinue continuous positive airway pressure on the morning of surgery
  4. Continue home positive airway pressure therapy and arrange postoperative monitoring Correct answer.

Explanation

Patients with obstructive sleep apnea benefit from continued positive airway pressure therapy and appropriate postoperative monitoring, ideally in a setting with capability for observation. Sedative premedication can worsen airway obstruction, and late-day scheduling reduces observation time. Optimal risk reduction involves maintaining therapy and planning monitoring.

Question 46Preanesthetic Assessment and Patient Preparation

Which preoperative finding in a patient with cirrhosis most strongly suggests increased anesthetic risk from hepatic decompensation?

  1. Total bilirubin of 0.8 mg/dL
  2. Serum albumin of 4.2 g/dL
  3. Platelet count of 250,000/mm3
  4. International normalized ratio of 2.1 Correct answer.

Explanation

An elevated international normalized ratio reflects impaired synthetic hepatic function and is part of the Model for End-Stage Liver Disease score, which correlates with perioperative mortality. Coagulopathy and hypoalbuminemia are markers of decompensation. Normal albumin, platelets, and bilirubin do not indicate decompensation.

Question 47Preanesthetic Assessment and Patient Preparation

A patient with a cardiac pacemaker is scheduled for surgery using monopolar electrocautery. What is the most appropriate preanesthetic consideration?

  1. Identify the device type and arrange perioperative interrogation and reprogramming Correct answer.
  2. Place the dispersive pad so current passes through the pacemaker generator
  3. Assume that modern pacemakers are immune to electromagnetic interference
  4. Discontinue all pacing support during the case

Explanation

Electromagnetic interference from electrocautery can inhibit pacing or cause inappropriate rapid pacing, so device type and dependency should be identified and interrogation arranged. Reprogramming to an asynchronous or non-sensing mode may be needed. The dispersive pad should be positioned so current does not traverse the generator.

Question 48Preanesthetic Assessment and Patient Preparation

A patient is scheduled for surgery and reports taking a monoamine oxidase inhibitor. Which preoperative consideration is most important?

  1. Continue the drug and avoid all opioids
  2. No adjustment is needed because monoamine oxidase inhibitors are safe with all anesthetic agents
  3. Consult the prescriber about tapering because of risk of hypertensive crisis with sympathomimetic agents Correct answer.
  4. Double the dose on the morning of surgery

Explanation

Monoamine oxidase inhibitors can interact with sympathomimetic drugs and meperidine to cause hypertensive crisis or serotonin syndrome, so prescriber consultation about tapering is warranted. Abrupt discontinuation also carries risk, so the decision is individualized. Continuing without adjustment or doubling the dose is unsafe.

Question 49Preanesthetic Assessment and Patient Preparation

A patient with severe aortic stenosis is being evaluated before elective surgery. Which hemodynamic goal should guide the anesthetic plan?

  1. Induce tachycardia to improve cardiac output
  2. Reduce preload with aggressive diuresis before induction
  3. Permit hypotension to reduce myocardial work
  4. Maintain preload and systemic vascular resistance while avoiding tachycardia Correct answer.

Explanation

In severe aortic stenosis, fixed outflow obstruction makes cardiac output dependent on preload, adequate afterload, and sinus rhythm. Tachycardia shortens diastolic filling time and worsens ischemia, while hypotension can cause severe hypoperfusion. Maintaining preload and systemic vascular resistance while avoiding tachycardia is the guiding principle.

Question 50Preanesthetic Assessment and Patient Preparation

A patient reports a prior episode of malignant hyperthermia in a first-degree relative. Which preoperative measure is most appropriate?

  1. Use succinylcholine as the sole paralytic
  2. Premedicate with dantrolene for all patients with this history
  3. Avoid triggering agents and prepare a dantrolene supply Correct answer.
  4. Proceed with volatile anesthetics and monitor temperature

Explanation

A family history of malignant hyperthermia warrants avoidance of volatile anesthetics and succinylcholine and availability of dantrolene. Genetic susceptibility should be evaluated, and a trigger-free technique chosen. Routine dantrolene pretreatment is not standard practice.