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Question 1Anesthesia pharmacology and physiological mechanisms

A 45-year-old healthy male is scheduled for elective laparoscopic cholecystectomy under total intravenous anaesthesia (TIVA). Which pharmacological property correctly describes the pharmacokinetic and pharmacodynamic profile of propofol?

  1. Its primary sedative effect is mediated via competitive antagonism at NMDA glutamate receptors in the cortex.
  2. Its metabolic clearance rate exceeds total hepatic blood flow, indicating substantial extrahepatic metabolism in the lungs and kidneys. Correct answer.
  3. The context-sensitive half-time remains strictly constant at 3 minutes regardless of whether the infusion lasts 1 hour or 12 hours.
  4. It produces marked stimulation of the baroreceptor reflex, leading to reflex compensatory tachycardia when arterial blood pressure drops.

Explanation

Propofol has a remarkably high total body clearance (1.5–2.2 L/min) that exceeds typical hepatic blood flow (~1.2 L/min), demonstrating significant extrahepatic elimination primarily occurring in the lungs and kidneys. It acts predominantly by allosterically enhancing gamma-aminobutyric acid (GABA) at GABAA receptors, increasing chloride ion conductance and hyperpolarizing neuronal membranes. Unlike volatile agents, propofol blunts the baroreceptor reflex, resulting in hypotension without compensatory tachycardia.

Question 2Anesthesia pharmacology and physiological mechanisms

An 82-year-old female with severe aortic stenosis and ischemic heart disease is undergoing emergency surgery for a perforated diverticulum. The anaesthesiologist considers etomidate for induction. What is the principal endocrine side effect associated with even a single induction dose of etomidate?

  1. Irreversible destruction of adrenal cortical zona fasciculata cells leading to permanent Addisonian crisis.
  2. Profound inhibition of thyroid peroxidase resulting in acute myxedema coma within 4 hours.
  3. Reversible dose-dependent inhibition of 11-beta-hydroxylase, blocking conversion of 11-deoxycortisol to cortisol for up to 24 hours. Correct answer.
  4. Stimulation of aldosterone synthase causing acute hyperaldosteronism, hypokalemia, and severe metabolic alkalosis.

Explanation

Etomidate contains an imidazole ring that binds directly to cytochrome P450 enzymes, specifically causing reversible inhibition of 11-beta-hydroxylase (CYP11B1) and to a lesser extent 17-alpha-hydroxylase. This blocks the enzymatic conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone to corticosterone, producing adrenocortical suppression that persists for 12 to 24 hours even after a single bolus. In critically ill and septic patients, this transient adrenocortical insufficiency has been correlated with increased mortality in several clinical trials.

Question 3Anesthesia pharmacology and physiological mechanisms

A 28-year-old male with severe acute asthma refractory to nebulized bronchodilators requires urgent intubation for respiratory exhaustion. Ketamine is selected as the induction agent. What pharmacological mechanism explains both its bronchodilatory property and its dissociative state?

  1. Non-competitive antagonism at NMDA receptors combined with indirect sympathomimetic release of endogenous catecholamines. Correct answer.
  2. Direct agonism of mu-opioid receptors coupled with postsynaptic GABAA receptor activation in the hippocampus.
  3. Selective blockade of muscarinic M3 receptors and inhibition of voltage-gated potassium channels in bronchial smooth muscle.
  4. Irreversible inhibition of monoamine oxidase leading to massive extracellular accumulation of histamine and serotonin.

Explanation

Ketamine produces dissociative anaesthesia primarily by non-competitive antagonism of the N-methyl-D-aspartate (NMDA) receptor at the phencyclidine binding site within the ion channel, interrupting thalamocortical and limbic projections. Its bronchodilatory effect is mediated both by direct smooth muscle relaxation and by indirect sympathomimetic action through central sympathetic stimulation and inhibition of neuronal catecholamine reuptake. In patients with depleted catecholamine stores (such as prolonged septic shock), ketamine can unmask its direct myocardial depressant effect.

Question 4Anesthesia pharmacology and physiological mechanisms

Which of the following volatile anaesthetics has the lowest blood-gas partition coefficient, resulting in the most rapid wash-in and wash-out pharmacokinetics during clinical anaesthesia?

  1. Isoflurane (blood-gas coefficient 1.40)
  2. Sevoflurane (blood-gas coefficient 0.65)
  3. Halothane (blood-gas coefficient 2.50)
  4. Desflurane (blood-gas coefficient 0.42) Correct answer.

Explanation

Desflurane has a blood-gas partition coefficient of approximately 0.42 at 37°C, which is the lowest among modern potent volatile anaesthetics (compared to sevoflurane at 0.65, isoflurane at 1.40, and halothane at 2.50). A low blood-gas solubility means that very little anaesthetic dissolves in the blood before partial pressure rises in the alveoli and brain, enabling the fastest induction and prompt emergence independent of case duration. However, desflurane requires a heated pressurized vaporizer (Tec 6) due to its high vapor pressure (669 mmHg at 20°C) and boiling point near room temperature (22.8°C).

Question 5Anesthesia pharmacology and physiological mechanisms

According to the guidelines of the Czech Society of Anaesthesiology, Resuscitation and Intensive Medicine (ČSARIM) and the European Society of Anaesthesiology and Intensive Care (ESAIC), what is the mandatory quantitative neuromuscular monitoring threshold required prior to safe tracheal extubation?

  1. Train-of-Four (TOF) ratio >= 0.50 (50%) measured at the orbicularis oculi muscle.
  2. Sustained head lift for 5 seconds without objective quantitative acceleromyography.
  3. Train-of-Four (TOF) ratio >= 0.90 (90%) measured quantitatively at the adductor pollicis muscle. Correct answer.
  4. Train-of-Four (TOF) count of 4 with palpable tactile absence of fade on manual stimulation.

Explanation

Current ČSARIM and ESAIC guidelines mandate quantitative neuromuscular monitoring before extubation, defining complete recovery as a Train-of-Four (TOF) ratio >= 0.90 (90%) measured at the adductor pollicis (innervated by the ulnar nerve). Clinical tests such as 5-second head lift, tongue protrusion, or manual tactile assessment of fade are subjective, unreliable, and cannot exclude residual neuromuscular blockade (TOF ratio 0.6–0.8), which is associated with airway obstruction, hypoxemia, and increased postoperative pulmonary complications.

Question 6Anesthesia pharmacology and physiological mechanisms

During elective surgery, an anaesthesiologist administers neostigmine (0.05 mg/kg) with glycopyrrolate when the patient already exhibits a spontaneous TOF ratio of 0.92. What paradoxical pharmacological complication can occur under these circumstances?

  1. Severe acute tachyarrhythmia due to excessive nicotinic stimulation of atrial pacemakers.
  2. Paradoxical muscle weakness and neuromuscular dysfunction caused by acetylcholine accumulation inducing depolarizing desensitization block. Correct answer.
  3. Rapid irreversible inactivation of plasma pseudocholinesterase leading to delayed clearance of volatile agents.
  4. Immediate severe bronchospasm refractory to high-dose beta-2 agonists due to complete beta-blockade.

Explanation

Neostigmine inhibits acetylcholinesterase, leading to acetylcholine accumulation in the synaptic cleft. When administered in the presence of full or near-complete neuromuscular recovery (TOF ratio > 0.90), the excessive concentration of synaptic acetylcholine causes persistent depolarization, receptor desensitization, and channel open-state inactivation, resulting in paradoxical muscle weakness, upper airway collapse, and impaired respiratory mechanics. Acetylcholinesterase inhibitors have a ceiling effect and should not be given without objective evidence of residual block (or when recovery is already near complete).

Question 7Anesthesia pharmacology and physiological mechanisms

A 35-year-old paraplegic patient who suffered a complete thoracic spinal cord transection 6 weeks ago requires urgent surgery for an acute incarcerated hernia. Why is succinylcholine strictly contraindicated in this patient?

  1. Risk of fatal hyperkalemia due to proliferation of extrajunctional nicotinic acetylcholine receptors across the entire muscle sarcolemma. Correct answer.
  2. High probability of triggering malignant hyperthermia specifically due to spinal denervation hypersensitivity.
  3. Complete resistance to depolarizing blockade requiring massive doses that cause permanent renal cortical necrosis.
  4. Rapid conversion of succinylcholine to toxic metabolites that selectively damage anterior horn motor neurons.

Explanation

Following denervation injuries (such as spinal cord transection, stroke, or severe burns) older than 24–48 hours, skeletal muscle fibers upregulate fetal and extrajunctional nicotinic acetylcholine receptors (containing alpha-7 homomers and alpha-1-beta-1-delta-gamma pentamers) along the entire sarcolemmal surface. When succinylcholine binds to these widespread receptors, extensive prolonged potassium efflux occurs, capable of elevating serum potassium by 2 to 7+ mmol/L within minutes, precipitating refractory cardiac arrest and ventricular fibrillation. This contraindication typically lasts from 48 hours to at least 1–2 years post-injury (or indefinitely in progressive neurodegenerative diseases).

Question 8Anesthesia pharmacology and physiological mechanisms

A 50-year-old male is receiving a target-controlled infusion of remifentanil for major abdominal surgery. Which statement accurately describes remifentanil pharmacokinetics and its clinical consequences?

  1. It is primarily metabolized by hepatic cytochrome P450 3A4, causing prolonged sedation in cirrhotic patients.
  2. Its context-sensitive half-time increases progressively from 4 minutes after 1 hour to over 45 minutes after 6 hours of infusion.
  3. It is hydrolyzed by non-specific plasma and tissue esterases, yielding a context-sensitive half-time of 3 to 4 minutes regardless of infusion duration. Correct answer.
  4. It is resistant to naloxone reversal due to non-covalent covalent bonding with the kappa-opioid receptor.

Explanation

Remifentanil is a synthetic piperidine-derivative mu-opioid agonist featuring an ester linkage that renders it susceptible to rapid hydrolysis by non-specific esterases in blood and tissues. As a result, its elimination half-life and context-sensitive half-time are uniquely short and stable (approximately 3–4 minutes), virtually independent of infusion duration, hepatic function, or renal clearance. Because of this rapid offset, postoperative analgesic plans (such as multimodal analgesia or longer-acting opioids) must be established prior to discontinuing remifentanil to avoid acute pain and hyperalgesia.

Question 9Anesthesia pharmacology and physiological mechanisms

In Target-Controlled Infusion (TCI) for total intravenous anaesthesia with propofol, how do the Marsh and Schnider pharmacokinetic-pharmacodynamic models differ in their central volume of distribution (V1) and covariate parameters?

  1. The Marsh model scales V1 strictly by total body weight, whereas the Schnider model uses a fixed small V1 (4.27 L) and incorporates age, height, weight, and lean body mass. Correct answer.
  2. The Marsh model is strictly an effect-site model incorporating age and gender, whereas Schnider can only target plasma concentration.
  3. The Schnider model scales V1 exponentially with body surface area and requires dosing exclusively on total body weight.
  4. The Marsh model incorporates electroencephalographic feedback directly into rate constants, whereas Schnider uses linear bolus calculations.

Explanation

The Marsh model is a three-compartment model in which the central volume of distribution (V1) is directly proportional to total body weight (V1 = 0.228 L/kg), without adjustments for age, height, or gender. In contrast, the Schnider model utilizes a fixed central compartment volume of 4.27 L and calculates peripheral volumes and clearances using age, weight, height, and lean body mass (calculated by James' formula). Because Schnider incorporates rapid rate constants (ke0 = 0.456 min^-1 vs older Marsh ke0 = 0.26 min^-1), it is particularly well-validated for effect-site (Ce) targeting and avoids overshooting in elderly patients.

Question 10Anesthesia pharmacology and physiological mechanisms

When configuring a Target-Controlled Infusion (TCI) of remifentanil using the Minto model, what critical covariate relationship must the anaesthesiologist recognize regarding elderly patients?

  1. Clearance and central volume of distribution increase with age, requiring higher target concentrations to achieve the same effect.
  2. Both metabolic clearance and central volume decrease with advancing age, necessitating lower infusion rates to maintain equivalent effect-site concentrations. Correct answer.
  3. Age has no mathematical effect on the Minto model parameters because esterase activity is completely age-invariant.
  4. The Minto model cannot be applied in patients over 50 years of age due to erratic esterase hydrolysis.

Explanation

The Minto model for remifentanil incorporates age, weight, height, and gender to calculate lean body mass and pharmacokinetic rate constants. With advancing age, both central compartment volume (V1) and systemic clearance decrease significantly, while brain sensitivity to opioids increases (EC50 decreases). Consequently, elderly patients require substantially lower infusion rates and lower target effect-site concentrations to achieve adequate analgesia while avoiding profound bradycardia, hypotension, and chest wall rigidity.

Question 11Anesthesia pharmacology and physiological mechanisms

A 60-year-old male is undergoing major surgery under general anaesthesia monitored with the Bispectral Index (BIS). The current BIS value is 45. The surgeon requests ketamine (0.5 mg/kg IV) for postoperative analgesia. How does ketamine alter the processed EEG and BIS reading?

  1. It produces profound burst suppression, causing the BIS to drop rapidly below 20.
  2. It has zero effect on EEG patterns or BIS values because it acts exclusively in the spinal cord.
  3. It increases high-frequency beta and gamma activity, causing a paradoxical rise in the BIS value despite deepening clinical anaesthesia. Correct answer.
  4. It induces isoelectric flatline EEG that renders processed EEG monitors unable to display numeric values.

Explanation

Ketamine acts primarily as an NMDA receptor antagonist, resulting in frontal neuronal disinhibition and an increase in high-frequency electroencephalographic power (beta and gamma oscillations, 30–50 Hz) combined with alternating theta activity. Because processed depth of anaesthesia monitors (such as BIS, Entropy, or SedLine) interpret high-frequency activity as signs of wakefulness, ketamine causes a paradoxical elevation of the BIS value (often increasing from 40–50 up to 65–80) even though the patient is in a deeper dissociative state.

Question 12Anesthesia pharmacology and physiological mechanisms

What is the primary neuroanatomical site of action through which dexmedetomidine induces its characteristic 'rousable' sedation without clinically significant respiratory depression?

  1. Inhibition of GABAA receptors in the ventral tegmental area.
  2. Blockade of 5-HT3 receptors in the solitary tract nucleus.
  3. Stimulation of opioid mu-receptors in the rostral ventrolateral medulla.
  4. Agonism of presynaptic alpha-2 adrenergic receptors in the locus coeruleus. Correct answer.

Explanation

Dexmedetomidine is a potent and highly selective alpha-2 adrenergic receptor agonist (alpha-2:alpha-1 selectivity ratio ~1600:1). Its sedative and hypnotic effects originate predominantly from stimulation of presynaptic alpha-2 receptors in the locus coeruleus of the pons, inhibiting norepinephrine release and disinhibiting descending inhibitory pathways to the ventrolateral preoptic nucleus. This mimics natural non-REM stage 3 sleep, allowing patients to be easily rousable by verbal stimuli without suppressing medullary respiratory drive.

Question 13Anesthesia pharmacology and physiological mechanisms

Which clinical scenario represents an absolute contraindication to the administration of nitrous oxide (N2O) during general anaesthesia due to its physical solubility characteristics?

  1. Tension pneumothorax or acute mechanical bowel obstruction with significant luminal distension. Correct answer.
  2. Elective laparoscopic appendectomy in a patient with well-controlled hypertension.
  3. Short gynecological hysteroscopy in an otherwise healthy 30-year-old female.
  4. Pediatric induction in an uncooperative child without congenital anomalies.

Explanation

Nitrous oxide has a blood-gas partition coefficient (0.47) that is 34 times greater than that of nitrogen (0.014). Consequently, N2O diffuses out of the blood and into closed, air-filled body cavities 34 times faster than nitrogen can diffuse out, leading to rapid expansion of non-compliant gas-filled compartments. In patients with a pneumothorax, bowel obstruction, venous air embolism, or recent retinal gas bubble placement, N2O can double or triple the volume/pressure of the closed space within 10 to 30 minutes, leading to tension pneumothorax, bowel ischemia/perforation, or blindness.

Question 14Anesthesia pharmacology and physiological mechanisms

After a suspected perioperative immediate hypersensitivity reaction, which listed acute-versus-baseline tryptase sampling approach can support assessment? A result does not independently confirm or exclude every anaphylactic reaction.

  1. A single blood draw immediately upon cardiac arrest, followed by skin testing within 12 hours.
  2. Serial blood samples taken at 1 to 2 hours after symptom onset, and a baseline sample taken at >= 24 hours post-event. Correct answer.
  3. Serial blood draws every 15 minutes for 6 hours, with diagnostic confirmation defined by a drop in tryptase below 1 ug/L.
  4. A single urine collection 48 hours after surgery to assess renal clearance of degraded histamine.

Explanation

An acute tryptase sample interpreted with a later baseline can support mast-cell activation assessment in the appropriate clinical context. Timing and the pattern matter, and a normal result does not exclude every anaphylactic event. Sampling does not replace immediate clinical care or identify the causative medicine by itself.

Question 15Anesthesia pharmacology and physiological mechanisms

A 32-year-old non-smoking female with a history of motion sickness is scheduled for thyroidectomy. Postoperatively, she will receive patient-controlled intravenous morphine. According to the simplified Apfel score, what is her risk category for Postoperative Nausea and Vomiting (PONV) and the recommended prophylaxis strategy?

  1. Low risk (1 risk factor, ~10% incidence); no pharmacological prophylaxis is indicated.
  2. Moderate risk (2 risk factors, ~40% incidence); single-agent metoclopramide at the end of surgery.
  3. High risk (4 risk factors, ~79% incidence); multimodal prophylaxis using at least 2 to 3 antiemetics from different classes. Correct answer.
  4. Extremely low risk; smoking history is the sole determinant of PONV risk.

Explanation

The simplified Apfel score identifies four independent risk factors for PONV: female sex, non-smoking status, history of PONV or motion sickness, and anticipated postoperative opioid use. This patient possesses all 4 risk factors, placing her in the highest risk category (~79% baseline incidence of PONV). International and ČSARIM consensus guidelines recommend multimodal prophylaxis in high-risk patients using 2 to 3 interventions from different pharmacological classes (e.g., dexamethasone at induction, ondansetron/droperidol at emergence, and consideration of total intravenous anaesthesia with propofol).

Question 16Anesthesia pharmacology and physiological mechanisms

A 70-year-old male received midazolam (7.5 mg IV) during colonoscopy and develops profound hypoventilation and somnolence. The physician administers flumazenil (0.2 mg IV) with immediate improvement. Why must the patient be monitored closely for recurrent sedation for at least 1 to 2 hours?

  1. Flumazenil acts as a partial agonist that converts to an active sedative metabolite after 30 minutes.
  2. Flumazenil permanently down-regulates central GABAA receptors, triggering delayed generalized seizures.
  3. Flumazenil induces acute hepatic glycogenolysis that impairs renal drug elimination.
  4. Flumazenil has a short elimination half-life (~50 minutes), which is substantially shorter than that of midazolam and other benzodiazepines. Correct answer.

Explanation

Flumazenil is a competitive antagonist at the benzodiazepine binding site on the GABAA receptor. Its elimination half-life is remarkably short (approximately 40 to 60 minutes) due to rapid hepatic clearance. Because midazolam (half-life 1.5–3 hours) and especially longer-acting benzodiazepines have longer durations of action than flumazenil, plasma concentrations of the agonist remain elevated while flumazenil is cleared, leading to the well-documented danger of resedation and recurrent respiratory depression.

Question 17Airway assessment, respiratory mechanics and ventilation

During preoperative airway evaluation, an anaesthesiologist performs the Upper Lip Bite Test (ULBT). The patient is unable to bite the upper lip with the lower incisors, failing to reach the vermilion border (Class 3). What does this specific anatomical finding predict?

  1. High probability of difficult direct laryngoscopy due to severely restricted mandibular subluxation. Correct answer.
  2. Complete impossibility of performing successful mask ventilation in all clinical situations.
  3. Normal glottic visualization because lack of mandibular movement improves direct line of sight.
  4. Significant elongation of the thyromental distance beyond 10 centimeters.

Explanation

The Upper Lip Bite Test (ULBT) assesses the range of mandibular excursion and jaw subluxation. Class 1 indicates the lower incisors can bite the upper lip above the vermilion border; Class 2 indicates biting below the vermilion border; and Class 3 indicates the lower incisors cannot bite the upper lip at all. A Class 3 ULBT is a validated, highly specific independent predictor of difficult direct laryngoscopy (Cormack-Lehane grade III/IV) because adequate mandibular subluxation is essential to displace tongue tissue into the submandibular space during laryngoscopy.

Question 18Airway assessment, respiratory mechanics and ventilation

When performing tracheal intubation with a hyperangulated videolaryngoscope blade (e.g., GlideScope), what essential operational technique differentiates it from conventional Macintosh direct laryngoscopy?

  1. The operator must align the oral, pharyngeal, and laryngeal axes into a straight line by applying maximum forward neck extension.
  2. The endotracheal tube can be introduced without any stylet because hyperangulated blades automatically guide the tube into the glottis.
  3. The glottis is visualized 'around the corner' on the screen without line of sight, requiring an endotracheal tube pre-shaped with a rigid stylet to a 60–90 degree angle. Correct answer.
  4. The blade should be inserted deeply into the esophagus to stabilize the larynx before withdrawing into the vallecula.

Explanation

Hyperangulated videolaryngoscope blades (such as GlideScope or McGrath X-blade) have a steep curvature (typically 60 degrees) that visualizes the glottis indirect 'around the anatomical corner' without requiring line-of-sight alignment of the oral, pharyngeal, and laryngeal axes. However, seeing the glottis does not guarantee easy tube delivery; the endotracheal tube must be pre-shaped with a dedicated rigid stylet (e.g., GlideRite stylet) to match the 60–90 degree blade curve to direct the tube tip into the laryngeal aperture.

Question 19Airway assessment, respiratory mechanics and ventilation

In the Difficult Airway Society (DAS) and Czech (ČSARIM) unanticipated difficult tracheal intubation guidelines for an adult patient, what is the maximum recommended number of intubation attempts in Plan A before transitioning to Plan B?

  1. Up to 6 attempts, provided different blade sizes are tested by junior trainees.
  2. Unlimited attempts as long as pulse oximetry remains above 92%.
  3. Exactly 1 attempt; any failure mandates immediate emergency surgical cricothyroidotomy.
  4. A maximum of 3 attempts (with a 4th attempt permitted only by an experienced colleague), while maintaining oxygenation between attempts. Correct answer.

Explanation

Both DAS and ČSARIM difficult airway algorithms strictly limit Plan A (tracheal intubation) to a maximum of 3 attempts (plus one additional attempt by an experienced senior colleague, total 3+1). Multiple repeated attempts cause progressive airway trauma, hemorrhage, and laryngeal edema, rapidly converting a 'cannot intubate, CAN ventilate' situation into a catastrophic 'cannot intubate, CANNOT ventilate' (CICO) emergency. If Plan A fails, the team must promptly transition to Plan B: maintaining oxygenation and airway rescue via a second-generation supraglottic airway device.

Question 20Airway assessment, respiratory mechanics and ventilation

Which specific design characteristics distinguish a second-generation supraglottic airway device (SAD, e.g., i-gel, LMA ProSeal, Ambu AuraGain) from a classic first-generation laryngeal mask?

  1. Incorporation of a dedicated gastric drainage channel and design modifications that provide higher oropharyngeal seal pressures (> 25–30 cmH2O). Correct answer.
  2. A built-in video chip that streams live images of the vocal cords directly to the anaesthesia monitor.
  3. An inflatable cuff made of natural latex designed to withstand ventilatory pressures exceeding 60 cmH2O without displacement.
  4. A double-lumen bronchial extension allowing selective one-lung ventilation.

Explanation

Second-generation supraglottic airway devices (SADs) are defined by two key clinical safety enhancements: an integrated gastric drain tube (allowing decompression of stomach gas, insertion of a gastric tube, and venting of regurgitated fluids away from the laryngeal inlet) and higher oropharyngeal seal pressures (often exceeding 25–30 cmH2O compared to ~15–20 cmH2O with first-generation masks). These features reduce aspiration risk and facilitate more effective positive-pressure ventilation during airway rescue.

Question 21Airway assessment, respiratory mechanics and ventilation

In a 'Cannot Intubate, Cannot Oxygenate' (CICO) emergency where facemask, supraglottic airway, and tracheal intubation have all failed and pulse oximetry is rapidly falling below 70%, what is the recommended frontline Emergency Front-of-Neck Access (eFONA) technique according to DAS and ČSARIM guidelines?

  1. Immediate wide longitudinal sternotomy followed by transpleural cardiopulmonary bypass cannulation.
  2. Scalpel-bougie-tube technique: laryngeal handshake, transverse stab through cricothyroid membrane, 90-degree scalpel rotation, coudé-tip bougie insertion, railroading cuffed 6.0 mm tube. Correct answer.
  3. Repeated blind passage of a narrow 18G intravenous cannula through the thyroid cartilage connected to high-frequency jet ventilation.
  4. Subglottic blunt scissor dissection down to the bifurcation of the mainstem bronchi with suction decompression.

Explanation

International difficult airway guidelines (DAS, ČSARIM, Vortex approach) endorse the 'scalpel-bougie-tube' technique as the fastest, most reliable method for emergency front-of-neck access (eFONA). The operator extends the neck, stabilizes the larynx ('laryngeal handshake'), identifies the cricothyroid membrane, makes a transverse stab incision with a #10 or #20 scalpel blade, rotates the blade 90 degrees to open the membrane, slides a coudé-tipped bougie into the trachea, and railroads a lubricated cuffed 5.0 to 6.0 mm endotracheal tube. Needle cricothyroidotomy techniques with jet ventilation suffer high failure rates, barotrauma, and subcutaneous emphysema.

Question 22Airway assessment, respiratory mechanics and ventilation

A 58-year-old male with severe neck irradiation, fixed mandibular contracture, and a fungating supraglottic tumor causing audible inspiratory stridor requires definitive airway control. Awake tracheal intubation (ATI) is planned. What is the safest pharmacological and technical strategy?

  1. Adequate airway mucosal topicalization with lidocaine, titrated sedation with dexmedetomidine or remifentanil preserving spontaneous ventilation, and flexible videobronchoscopic intubation. Correct answer.
  2. Rapid sequence induction using 2 mg/kg propofol and 1.2 mg/kg rocuronium to instantly ablate laryngeal spasms before attempting bronchoscopy.
  3. Deep inhalation induction with 8% sevoflurane in 100% oxygen with the patient placed in the deep Trendelenburg position.
  4. Administration of high-dose intravenous midazolam (10 mg) combined with curarization to paralyze pharyngeal muscles.

Explanation

In an anticipated difficult airway with upper airway pathology and stridor, Awake Tracheal Intubation (ATI) is the gold-standard recommendation by ČSARIM, DAS, and the European Airway Management Society (EAMS). Meticulous airway topicalization using lidocaine (staying within the safe toxic threshold of 9 mg/kg lean mass) combined with cautious, titrated sedation using dexmedetomidine or remifentanil maintains patient cooperation and spontaneous respiration. Inducing general anaesthesia or administering muscle relaxants in a patient with critical airway narrowing can precipitate total airway collapse and fatal CICO.

Question 23Airway assessment, respiratory mechanics and ventilation

High-Flow Nasal Oxygen (HFNO / THRIVE) is increasingly utilized for preoxygenation and apnoeic oxygenation during difficult airway management. What physiological mechanism explains its ability to prolong safe apnoea time?

  1. It delivers 100% pressurized helium to dramatically increase alveolar gas diffusion rates.
  2. It generates continuous negative intrathoracic suction that draws oxygen across alveolar capillary membranes.
  3. Continuous microvascular oxygen uptake by pulmonary capillary blood creates a subatmospheric alveolar pressure gradient (aventilatory mass flow), while high-flow gas flushes anatomical dead space. Correct answer.
  4. It mechanically oscillates the tracheal tree at 300 cycles per minute to produce active carbon dioxide exhalation equivalent to tidal breathing.

Explanation

HFNO (Transnasal Humidified Rapid-Insufflation Ventilatory Exchange, THRIVE) delivers heated, humidified 100% oxygen at up to 70 L/min. Because the alveolar uptake of oxygen into capillary blood (~250 mL/min) is significantly faster than the diffusion of carbon dioxide into the alveoli (~20 mL/min), a net negative alveolar pressure is generated. This creates continuous mass flow of oxygen from the pharynx into the alveoli (apnoeic oxygenation). Concurrently, continuous turbulent gas flow flushes expired CO2 from the upper airway dead space, slowing the rate of PaCO2 accumulation to ~0.15–0.25 kPa/min (compared to ~0.4–0.6 kPa/min during static apnoea).

Question 24Airway assessment, respiratory mechanics and ventilation

A patient is undergoing left lower lobectomy requiring lung isolation. Why is a left-sided double-lumen tube (DLT) preferred over a right-sided DLT in the vast majority of thoracic surgical cases?

  1. The left main bronchus is significantly wider and shorter than the right main bronchus, reducing tube resistance.
  2. Right-sided DLTs are strictly incompatible with all modern flexible bronchoscopes.
  3. The left bronchial cuff automatically seals the right main bronchus without requiring cuff inflation.
  4. The anatomical distance from the carina to the right upper lobe bronchus is very short (1.5 to 2.0 cm), creating a high risk of right upper lobe atelectasis with a right-sided DLT. Correct answer.

Explanation

In adults, the left mainstem bronchus is long (~4.5–5.0 cm) before branching into secondary lobar bronchi, providing a generous margin of safety for placing and inflating a left bronchial cuff without occluding lobar orifices. In contrast, the right upper lobe (RUL) bronchus branches off the right main bronchus only 1.5 to 2.0 cm from the carina. A right-sided DLT requires a slotted bronchial cuff precisely aligned with the RUL takeoff; slight malpositioning causes right upper lobe atelectasis or hypoxemia, making left-sided DLTs the preferred choice for both left- and right-sided procedures (unless surgery directly involves the left main bronchus).

Question 25Airway assessment, respiratory mechanics and ventilation

In thoracic anaesthesia, in which clinical scenario is an independent bronchial blocker distinctly preferred over a standard double-lumen endotracheal tube (DLT)?

  1. When continuous high-volume bronchoscopic suctioning of massive bilateral hemoptysis is required.
  2. In a patient with a known difficult airway, existing tracheostomy, or when selective lobar collapse is desired. Correct answer.
  3. When rapid alternating lung isolation must be switched back and forth every 2 minutes.
  4. In open pneumonectomy where the mainstem bronchus must be transected flush at the tracheal carina.

Explanation

Bronchial blockers (e.g., Arndt, Cohen, EZ-Blocker) offer distinct advantages over DLTs when the patient has a known difficult airway (intubation can proceed with a single-lumen tube or through a videolaryngoscope/FOB), when a tracheostomy is present, in pediatric thoracic surgery, or when selective single-lobe isolation is desired while maintaining ventilation to the remaining ipsilateral lobe. A standard single-lumen tube can remain in place postoperatively for mechanical ventilation without requiring risky tube exchanges.

Question 26Airway assessment, respiratory mechanics and ventilation

On postoperative day 3 following a surgical tracheostomy, a patient accidentally dislodges the tracheostomy tube during coughing and becomes acutely cyanotic and hypoxic. What is the fundamental anatomical hazard and correct immediate management strategy?

  1. The stoma is fully epithelialized and can be rapidly cannulated with any size tube using forceful blind pressure.
  2. Emergency chest tube insertion is mandatory because tracheal displacement always causes bilateral tension pneumothorax.
  3. Definitive surgical re-exploration must await 24 hours of conservative mask oxygenation.
  4. The stoma tract is immature (< 7 days); blind reinsertion risks creating a false pretracheal tract and fatal airway compression. Oxygenate via upper airway and stoma, and prepare for oral intubation if recannulation fails. Correct answer.

Explanation

A tracheostomy stoma does not form a mature, epithelialized tract until at least 7 to 10 days postoperatively. In the first few days, the tissue planes between the skin and anterior tracheal wall are loose; blind attempts to force a tracheostomy tube back into the stoma frequently displace it into the pretracheal or paratracheal tissue, creating a false tract, causing subcutaneous emphysema, and compressing the trachea. The initial response (per National Tracheostomy Safety Project guidelines) is to call for help, provide 100% O2 to both the face and stoma, and perform gentle reinsertion over a suction catheter or immediately intubate orally from above if the airway cannot be restored.

Question 27Airway assessment, respiratory mechanics and ventilation

A 48-year-old male with a BMI of 46 kg/m2 presents for bariatric surgery. In the operating room, why is positioning the patient in the 'ramped' position (head-elevated laryngoscopy position) critical prior to induction?

  1. It aligns the external auditory meatus with the sternal notch in the horizontal plane, optimizing line of sight, expanding functional residual capacity (FRC), and prolonging safe apnoea time. Correct answer.
  2. It promotes blood pooling in the splanchnic circulation, causing therapeutic hypotension that eliminates blood loss.
  3. It fully compresses the posterior pharyngeal wall against the cervical spine, preventing gastroesophageal regurgitation.
  4. It increases closing capacity to exceed total lung capacity, thereby preventing alveolar atelectasis.

Explanation

In morbidly obese patients, supine positioning severely reduces functional residual capacity (FRC) because excessive chest wall and abdominal mass push the diaphragm cephalad, accelerating desaturation during apnoea. The 'ramped' position (achieved using blankets or dedicated ramp pillows to align the external auditory meatus horizontally with the sternal notch) aligns the anatomical axes of the airway for optimal videolaryngoscopy/direct laryngoscopy, unloads the diaphragm to improve FRC, and significantly prolongs safe non-hypoxic apnoea time during induction.

Question 28Airway assessment, respiratory mechanics and ventilation

A patient with a documented difficult intubation following major neck dissection is ready for extubation. According to Difficult Airway Society (DAS) and ČSARIM extubation guidelines, how should the extubation of an 'at-risk' airway be safely managed?

  1. Perform extubation while in deep surgical anaesthesia with high-dose volatile agent to completely prevent cough reflexes.
  2. Ensure full reversal of neuromuscular blockade (TOF ratio >= 0.90), patient awake and obeying commands, and consider extubation over an Airway Exchange Catheter (AEC) or staged extubation device. Correct answer.
  3. Deflate the cuff and extubate immediately in the recovery room without suctioning or monitoring equipment present.
  4. Administer 100 mg of succinylcholine immediately before pulling the tube to relax laryngeal adductors.

Explanation

Extubation of an 'at-risk' airway carries substantial risk of acute airway failure. Guidelines emphasize that extubation is an elective, planned procedure requiring: full reversal of neuromuscular blockade (quantitative TOF >= 0.90), return of protective airway reflexes, patient awake and following commands, suctioning of the pharynx, and availability of difficult airway rescue equipment. In high-risk cases, extubating over an Airway Exchange Catheter (AEC) provides a conduit for supplemental oxygenation and a secure guide for rapid reintubation if airway deterioration occurs.

Question 29Airway assessment, respiratory mechanics and ventilation

According to the PROSEVA trial and international guidelines, what are the primary clinical indications and procedural requirements for prone positioning in patients with severe ARDS?

  1. Indicated for mild ARDS (PaO2/FiO2 250–300 mmHg); prone sessions should last exactly 2 hours twice daily.
  2. Indicated only after cardiac arrest occurs; sessions should be terminated immediately upon any drop in blood pressure.
  3. Indicated for severe ARDS with PaO2/FiO2 < 150 mmHg (on FiO2 >= 0.6 and PEEP >= 5 cmH2O); sessions must be maintained for at least 16 consecutive hours. Correct answer.
  4. Indicated exclusively in patients with unstable cervical spine fractures to stabilize the posterior ligaments.

Explanation

The PROSEVA trial proved that early, prolonged prone positioning significantly reduces 28-day and 90-day mortality in severe ARDS. The clinical indication is a PaO2/FiO2 ratio < 150 mmHg despite optimization of ventilator settings (FiO2 >= 0.6, PEEP >= 5 cmH2O, tidal volume 6 mL/kg PBW). Prone sessions must be maintained for at least 16 consecutive hours per day. Prone positioning promotes more uniform distribution of transpulmonary pressure, recruits dorsal lung regions, improves ventilation-perfusion matching, and reduces right ventricular strain.

Question 30Airway assessment, respiratory mechanics and ventilation

Regarding the use of continuous neuromuscular blockade (cisatracurium infusion) in early severe ARDS, how do modern clinical guidelines (such as Surviving Sepsis Campaign and ČSARIM) interpret the evidence from the ACURASYS and ROSE trials?

  1. Continuous paralysis is mandatory for all ARDS patients for a minimum of 14 days regardless of severity.
  2. Neuromuscular blockers are completely banned in ARDS due to 100% incidence of irreversible critical illness myopathy.
  3. Paralysis should only be given as intermittent boluses to achieve an intracranial pressure < 5 mmHg.
  4. Routine continuous paralysis is not recommended for all ARDS; it is reserved for early severe ARDS (PaO2/FiO2 < 150 mmHg) with persistent ventilator dyssynchrony, elevated driving pressure, or refractory hypoxemia, limited to 48 hours. Correct answer.

Explanation

While the ACURASYS trial (2010) suggested a 90-day survival benefit with 48 hours of cisatracurium in severe ARDS, the subsequent larger PETAL Network ROSE trial (2019) showed no mortality difference when neuromuscular blockade was compared to light sedation with protocolized lung-protective ventilation. Current guidelines recommend that continuous neuromuscular blockade should not be used routinely in all ARDS patients, but is indicated as a targeted 48-hour intervention in patients with early severe ARDS (PaO2/FiO2 < 150 mmHg) who exhibit severe patient-ventilator dyssynchrony, breath-stacking (reverse triggering), or high transpulmonary driving pressures unresponsive to sedation.

Question 31Airway assessment, respiratory mechanics and ventilation

A 38-year-old male with severe viral ARDS remains hypoxemic with a PaO2/FiO2 ratio of 58 mmHg and severe uncompensated respiratory acidosis (pH 7.12, PaCO2 74 mmHg) despite 18 hours of prone positioning, neuromuscular paralysis, and PEEP titration. Based on the EOLIA trial criteria, what is the appropriate escalation of therapy?

  1. Initiation of Veno-Venous Extracorporeal Membrane Oxygenation (VV-ECMO). Correct answer.
  2. Immediate conversion to negative-pressure iron lung ventilation.
  3. Emergency bilateral pneumonectomy followed by mechanical ventilation.
  4. Administration of 100 mg intravenous furosemide bolus followed by fluid restriction to 10 mL/h.

Explanation

The patient meets criteria for Veno-Venous ECMO (VV-ECMO) based on the landmark EOLIA trial and Extracorporeal Life Support Organization (ELSO) guidelines: severe ARDS with PaO2/FiO2 < 80 mmHg for > 6 hours (or < 50 mmHg for > 3 hours) or severe hypercapnic respiratory acidosis (pH < 7.15 with PaCO2 >= 60 mmHg for > 6 hours with plateau pressure maintained <= 32 cmH2O) despite optimization of conventional therapies including prone positioning and paralysis. VV-ECMO provides extracorporeal oxygenation and decarboxylation, allowing ultra-protective lung ventilation (resting the lungs) to prevent further ventilator-induced lung injury (VILI).

Question 32Airway assessment, respiratory mechanics and ventilation

During one-lung ventilation (OLV) for thoracic surgery, what physiological mechanism diverts blood flow away from the non-ventilated, collapsed lung, and how do anaesthetic drugs influence this response?

  1. Hypoxic Pulmonary Vasoconstriction (HPV); volatile anaesthetics inhibit HPV in a dose-dependent manner (> 1 MAC), whereas propofol preserves HPV intact. Correct answer.
  2. Hypoxic Pulmonary Vasodilation; propofol completely abolishes the reflex while nitrous oxide stimulates it.
  3. Beta-2 adrenergic bronchoconstriction; all intravenous anaesthetics trigger severe pulmonary hypertension in the ventilated lung.
  4. Nitric oxide synthetase hyperactivation; volatile anaesthetics double pulmonary capillary resistance exclusively in ventilated alveoli.

Explanation

Hypoxic Pulmonary Vasoconstriction (HPV) is an essential homeostatic reflex whereby alveolar hypoxia (low alveolar PO2) triggers smooth muscle constriction in the pulmonary arterioles of non-ventilated lung regions. During one-lung ventilation (OLV), HPV reduces blood flow to the collapsed lung by approximately 40–50%, diverting perfusion toward the ventilated, oxygenated lung and dramatically reducing intrapulmonary shunt and hypoxemia. Inhalational anaesthetics inhibit HPV in a dose-dependent fashion (particularly at concentrations > 1 MAC), whereas intravenous agents like propofol (TIVA) have no inhibitory effect on HPV, preserving optimal ventilation-perfusion matching.

Question 33Airway assessment, respiratory mechanics and ventilation

Why do neonates and infants desaturate significantly faster than adults during periods of hypoventilation or apnoea under general anaesthesia?

  1. Higher metabolic rate and oxygen consumption (6–8 mL/kg/min) combined with a lower Functional Residual Capacity (FRC) and high chest wall compliance. Correct answer.
  2. Presence of fetal hemoglobin (HbF) which releases oxygen 10 times faster than adult hemoglobin.
  3. Complete lack of pulmonary surfactant until 2 years of chronological age.
  4. Total absence of peripheral chemoreceptor activity in the carotid bodies.

Explanation

Rapid arterial desaturation in infants is the direct consequence of unfavorable respiratory mechanics and high metabolic demands. Oxygen consumption in neonates and infants is 6 to 8 mL/kg/min (more than double the adult rate of ~3 mL/kg/min). Conversely, Functional Residual Capacity (FRC, the body's oxygen reserve) is relatively small (~30 mL/kg), and closing capacity is high, encroaching on normal tidal breathing. Furthermore, the infant chest wall is highly compliant (cartilaginous ribs with low outward recoil), so FRC is dynamically maintained only by active diaphragmatic braking and laryngeal adduction. When general anaesthesia ablates muscle tone, FRC collapses, and the high oxygen consumption rapidly exhausts alveolar oxygen within seconds of apnoea.

Question 34Hemodynamic monitoring, shock and circulation

An intensivist assesses volume responsiveness in an intubated septic patient. Under which specific cardiopulmonary conditions are dynamic arterial waveform indices (such as Pulse Pressure Variation [PPV] and Stroke Volume Variation [SVV]) considered physiologically valid?

  1. In spontaneously breathing patients receiving non-invasive ventilation with high inspiratory effort.
  2. In patients with frequent multifocal ventricular extrasystoles and atrial fibrillation.
  3. In patients under fully passive mechanical ventilation with regular sinus rhythm, tidal volume >= 8 mL/kg predicted body weight, and normal chest wall compliance. Correct answer.
  4. In patients ventilated with low tidal volume (4 mL/kg PBW) and high spontaneous trigger sensitivity.

Explanation

Dynamic indices of fluid responsiveness (PPV and SVV) rely on cyclic heart-lung interactions induced by positive-pressure ventilation. They are physiologically valid ONLY when: (1) the patient is on full passive mechanical ventilation without spontaneous breathing efforts; (2) tidal volume is at least 8 mL/kg of predicted body weight; (3) the cardiac rhythm is regular sinus (arrhythmias disrupt cyclic variations); and (4) respiratory compliance is not severely reduced. If these criteria are unmet, dynamic indices produce false negatives; in such cases, the Passive Leg Raising (PLR) test with real-time stroke volume measurement is preferred.

Question 35Hemodynamic monitoring, shock and circulation

A 68-year-old male with an acute anterior myocardial infarction develops cardiogenic shock. A pulmonary artery catheter (PAC) is placed. Which hemodynamic profile is characteristic of classic cardiogenic shock?

  1. Low cardiac index (< 2.2 L/min/m2), elevated pulmonary artery wedge pressure (PAWP > 18 mmHg), and high systemic vascular resistance index (SVRI). Correct answer.
  2. High cardiac index (> 4.0 L/min/m2), low pulmonary artery wedge pressure (PAWP < 8 mmHg), and severely depressed SVRI.
  3. Normal cardiac index, normal PAWP, and profound pulmonary hypertension with normal right ventricular end-diastolic pressure.
  4. Low cardiac index, low PAWP (< 6 mmHg), and low central venous pressure with normal SVRI.

Explanation

Classic cardiogenic shock is characterized by severe pump failure leading to reduced tissue perfusion and backward congestion: a depressed cardiac index (CI < 2.2 L/min/m2 without support), elevated left ventricular filling pressure reflected by Pulmonary Artery Wedge Pressure (PAWP > 15–18 mmHg), elevated Central Venous Pressure (CVP), and compensatory systemic vasoconstriction resulting in an elevated Systemic Vascular Resistance Index (SVRI > 2400 dyn*s/cm5/m2). Treatment focuses on inotropes (dobutamine, milrinone), afterload reduction if tolerated, mechanical circulatory support, and urgent coronary revascularization.

Question 36Hemodynamic monitoring, shock and circulation

A patient with refractory cardiogenic shock is supported with peripheral femoral-femoral Veno-Arterial (VA) ECMO. After 48 hours, the native left ventricle begins to recover, but the patient develops severe concomitant ARDS. Pulse oximetry on the right hand reads 78%, while the ECMO circuit arterial line and left femoral line read 99%. What is this phenomenon and its management?

  1. Systemic heparin-induced thrombocytopenia; administer high-dose protamine.
  2. Harlequin syndrome (North-South / dual circulation syndrome); manage by improving lung ventilation, adding an internal jugular venous return cannula (V-A-V ECMO), or converting to central cannulation. Correct answer.
  3. Massive intracardiac right-to-left shunt via a ventricular septal defect requiring emergent closure.
  4. Acute aortic dissection caused by high ECMO retrograde jet velocities requiring immediate decannulation.

Explanation

In peripheral femoral VA-ECMO, oxygenated blood is pumped retrogradely up the aorta against native left ventricular (LV) ejection. When the native heart recovers contractile function but the lungs remain severely diseased (poor oxygenation), deoxygenated blood ejected from the LV traverses the aortic arch to supply the brachiocephalic trunk (right arm, right carotid artery) and coronary vessels ('North'), while retrograde oxygenated ECMO blood perfuses the lower body ('South'). This 'Harlequin' or dual circulation syndrome causes cerebral and myocardial hypoxia. Management involves optimizing lung ventilation/PEEP, repositioning the reinfusion cannula, converting to V-A-V configuration (adding an internal jugular return cannula to oxygenate blood entering the native heart), or central VA-ECMO.

Question 37Hemodynamic monitoring, shock and circulation

An 80-year-old female with severe, symptomatic aortic stenosis (aortic valve area 0.7 cm2, mean gradient 48 mmHg) requires emergency open reduction and internal fixation of a hip fracture. What are the key hemodynamic management goals during anaesthesia?

  1. Promote rapid sinus tachycardia (HR > 120 bpm) and decrease systemic vascular resistance to allow fast forward flow.
  2. Maintain normal sinus rhythm, avoid tachycardia and severe bradycardia (target HR 60–80 bpm), maintain preload, and preserve adequate systemic vascular resistance (afterload). Correct answer.
  3. Induce marked vasodilation using continuous high-dose sodium nitroprusside infusion to unload the left ventricle.
  4. Target low normal mean arterial pressure (MAP 40–50 mmHg) to reduce the transvalvular pressure gradient.

Explanation

Severe aortic stenosis represents a fixed mechanical outflow obstruction with concentric left ventricular hypertrophy. The stiff, non-compliant LV is critically dependent on atrial contraction ('atrial kick', providing 25–40% of ventricular filling); therefore, maintaining sinus rhythm is paramount. Tachycardia must be avoided because it dramatically reduces diastolic coronary perfusion time while increasing myocardial oxygen demand, precipitating subendocardial ischemia. Vasodilation and hypotension must be aggressively prevented because the hypertrophied myocardium requires high aortic root diastolic pressures to maintain coronary perfusion; phenylephrine or norepinephrine is used to maintain systemic vascular resistance.

Question 38Hemodynamic monitoring, shock and circulation

A 42-year-old male with Hypertrophic Obstructive Cardiomyopathy (HOCM) undergoes general anaesthesia. Intraoperatively, he develops sudden severe hypotension and a new harsh systolic ejection murmur. Transesophageal echocardiography confirms Systolic Anterior Motion (SAM) of the anterior mitral leaflet with severe left ventricular outflow tract (LVOT) obstruction. Which pharmacological interventions are strictly contraindicated, and what is the correct treatment?

  1. Inotropes (e.g., dobutamine, dopamine, epinephrine) and vasodilators are strictly contraindicated; treat with intravenous volume loading, alpha-1 vasoconstrictor (phenylephrine), and beta-blockers (esmolol). Correct answer.
  2. Phenylephrine and beta-blockers are contraindicated; treat with high-dose isoproterenol and glyceryl trinitrate.
  3. Intravenous fluid administration is contraindicated; treat with immediate high-dose furosemide and sodium nitroprusside.
  4. Direct current cardioversion is contraindicated; treat with intravenous milrinone bolus followed by hydralazine.

Explanation

In Hypertrophic Obstructive Cardiomyopathy (HOCM), LVOT obstruction is dynamic and exacerbated by anything that reduces LV cavity size or increases velocity of ejection (the Venturi effect), which pulls the anterior mitral valve leaflet toward the hypertrophied septum (SAM). Positive inotropic agents (dobutamine, epinephrine, dopamine) increase contractility, while vasodilators and hypovolemia reduce ventricular volume, drastically worsening the obstruction and causing hemodynamic collapse. The definitive management is to expand LV end-diastolic volume and afterload: administer IV crystalloid boluses, increase SVR using pure alpha-1 agonists (phenylephrine or norepinephrine), and slow the heart rate using beta-blockers (e.g., esmolol) to lengthen diastolic filling time.

Question 39Hemodynamic monitoring, shock and circulation

During a posterior fossa craniotomy performed in the sitting position, the anaesthesiologist notes a sudden drop in End-Tidal Carbon Dioxide (ETCO2) from 36 to 18 mmHg, accompanied by an acute drop in blood pressure and a 'mill-wheel' churning sound on the precordial Doppler. What is the diagnosis and immediate management?

  1. Acute massive bronchospasm; administer 500 ug subcutaneous salbutamol and ventilate with 100% nitrous oxide.
  2. Venous Air Embolism (VAE); notify surgeon to flood the wound with saline, discontinue nitrous oxide, apply 100% O2, aspirate air from right atrial catheter, and compress jugular veins. Correct answer.
  3. Anaphylactic shock to chlorhexidine; administer intravenous epinephrine 1 mg bolus and start chest compressions immediately.
  4. Endotracheal tube extubation; immediately remove the tube and perform emergency surgical tracheostomy.

Explanation

The sitting position creates a substantial negative hydrostatic pressure gradient between the open dural venous sinuses and the right atrium, predisposing to Venous Air Embolism (VAE). Entrained air enters the pulmonary circulation, causing mechanical obstruction of pulmonary arterioles, an acute rise in dead space ventilation (manifested as an immediate precipitous drop in ETCO2 and rise in PaCO2), acute right ventricular strain, and hypotension; precordial Doppler ultrasound is the most sensitive non-invasive monitor. Immediate management: (1) notify surgical team to immediately flood the operative field with irrigation fluid and wax exposed bone edges; (2) discontinue nitrous oxide immediately (N2O diffuses into air bubbles, expanding their size); (3) administer 100% O2; (4) aspirate air from a dedicated central venous/multiorifice right atrial catheter (Bunegin-Albin catheter); (5) perform bilateral jugular vein compression to elevate cranial venous pressure; and (6) support hemodynamics with fluids and vasopressors.

Question 40Hemodynamic monitoring, shock and circulation

According to modern Patient Blood Management (PBM) concepts and European Society of Anaesthesiology and Intensive Care (ESAIC) guidelines, what are the three fundamental clinical pillars of PBM?

  1. Routine preoperative autologous blood donation, mandatory transfusion for any Hb < 100 g/L, and high-dose intravenous heparinization.
  2. Routine whole-blood transfusion before skin incision, total restriction of crystalloid fluids, and avoidance of all antifibrinolytics.
  3. Detection and treatment of preoperative anaemia (Pillar 1), minimization of perioperative blood loss and bleeding (Pillar 2), and optimization of patient-specific physiological tolerance of anaemia using restrictive transfusion triggers (Pillar 3). Correct answer.
  4. Preoperative erythrocytapheresis, continuous infusion of recombinant activated Factor VII, and targeting a hematocrit > 50%.

Explanation

Patient Blood Management (PBM) is an evidence-based, multidisciplinary standard endorsed by the World Health Organization (WHO), ČSARIM, and ESAIC. It is structured around Three Pillars: (1) Pillar 1 (Preoperative): detect, diagnose, and treat preoperative anaemia (evaluating iron deficiency, treating with oral or intravenous iron +/- ESA) and optimizing hemostasis; (2) Pillar 2 (Intraoperative): minimize perioperative blood loss (meticulous surgical technique, cell salvage, tranexamic acid, point-of-care viscoelastic testing, normothermia); and (3) Pillar 3 (Postoperative): optimize patient-specific physiological reserve and adhere to restrictive red blood cell transfusion thresholds (typically Hb 70–80 g/L in hemodynamically stable patients without acute coronary syndromes).

Question 41Hemodynamic monitoring, shock and circulation

A 72-year-old male on dabigatran (150 mg twice daily) for non-valvular atrial fibrillation presents with acute intracranial hemorrhage following a fall. Which specific antidote provides immediate, targeted reversal of dabigatran?

  1. Andexanet alfa (modified recombinant inactive Factor Xa).
  2. Idarucizumab (a humanized monoclonal antibody Fab fragment that binds dabigatran with 350-fold higher affinity than thrombin). Correct answer.
  3. Protamine sulfate combined with vitamin K1 (phytomenadione).
  4. Fresh Frozen Plasma (10 mL/kg) administered over 12 hours.

Explanation

Idarucizumab (Praxbind) is a specific humanized monoclonal antibody antigen-binding fragment (Fab) designed specifically for the rapid reversal of the direct oral thrombin inhibitor dabigatran. It binds free and thrombin-bound dabigatran with an affinity approximately 350 times higher than that of dabigatran for thrombin, neutralizing its anticoagulant effect within minutes of administration (standard dose is 5 g IV, given as two consecutive 2.5 g vials). Andexanet alfa is the specific reversal agent for Factor Xa inhibitors (apixaban, rivaroxaban), not dabigatran.

Question 42Hemodynamic monitoring, shock and circulation

During cardiac arrest resuscitation under the European Resuscitation Council (ERC) guidelines, the team actively identifies and treats reversible causes structured as the '4 H's and 4 T's'. Which set represents these reversible etiologies?

  1. Hypoglycemia, Hyperthermia, Hyperventilation, Hemophilia; Tremor, Trismus, Tetanus, Thyroid storm.
  2. Hypoxia, Hypercholesterolemia, Hemothorax, Hepatitis; Thrombocytopenia, Tuberculosis, Trauma, Toxoplasmosis.
  3. Hypoxia, Hypovolemia, Hyperkalemia/hypokalemia/metabolic, Hypothermia/hyperthermia; Thrombosis (coronary/pulmonary), Tension pneumothorax, Tamponade (cardiac), Toxins. Correct answer.
  4. Hypotension, Hypoalbuminemia, Hyponatremia, Hypomagnesemia; Tracheitis, Tracheomalacia, Tonsillitis, Tendinitis.

Explanation

The European Resuscitation Council (ERC) and international resuscitation guidelines structure reversible causes of cardiac arrest into the mnemonic '4 H's and 4 T's': (1) Hypoxia; (2) Hypovolemia; (3) Hyperkalemia / hypokalemia / other metabolic disorders (severe acidosis, hypocalcemia); (4) Hypothermia / hyperthermia; and (5) Thrombosis (coronary - acute myocardial infarction, or pulmonary - massive pulmonary embolism); (6) Tension pneumothorax; (7) Tamponade (cardiac); (8) Toxins (overdoses, local anaesthetic toxicity, accidental poisonings). Systematic ultrasound (POCUS) and targeted therapies (e.g., thoracostomy, pericardiocentesis, calcium, thrombolysis, lipid emulsion) are guided by this framework.

Question 43Hemodynamic monitoring, shock and circulation

A 42-year-old male collapses while jogging; bystander CPR begins within 1 minute, and emergency medical services arrive in 5 minutes finding ventricular fibrillation. Despite 20 minutes of advanced life support, refractory cardiac arrest persists. According to international and Czech Extracorporeal Life Support (ECLS) guidelines, what clinical criteria identify this patient as an ideal candidate for Extracorporeal Cardiopulmonary Resuscitation (eCPR)?

  1. Witnessed arrest, immediate high-quality bystander CPR, initial shockable rhythm (VF/pVT), young age (< 65–70 years), and ability to establish veno-arterial ECMO flow within 60 minutes of collapse. Correct answer.
  2. Unwitnessed arrest in an elderly patient (> 85 years) found in asystole with unknown down-time.
  3. Patients with active terminal malignancy, severe baseline dementia, and irreversible multiorgan failure.
  4. Cardiac arrest due to known massive intracranial hemorrhage with bilateral fixed dilated pupils.

Explanation

Extracorporeal Cardiopulmonary Resuscitation (eCPR) involves the rapid deployment of veno-arterial (VA) ECMO during ongoing cardiac arrest to restore systemic perfusion and end-organ oxygenation when conventional CPR fails. Evidence from the Prague OHCA study and international ELSO guidelines demonstrates that eCPR achieves meaningful survival with favorable neurological outcomes when applied to strictly selected patients. Ideal inclusion criteria include: (1) witnessed cardiac arrest; (2) immediate bystander CPR (low no-flow time); (3) initial shockable rhythm (VF/pVT); (4) age < 65 to 70 years; (5) low-flow time (collapse to ECMO pump start) < 60 minutes (or < 45–60 min); (6) end-tidal CO2 > 10–15 mmHg during CPR (indicating adequate chest compressions); and (7) absence of known catastrophic non-cardiac causes (e.g., fatal head trauma, terminal malignancy).

Question 44Perioperative assessment, regional anatomy and pain

A 45-year-old male with a newly diagnosed pheochromocytoma is scheduled for laparoscopic adrenalectomy. Why must preoperative medical optimization strictly initiate alpha-adrenergic blockade prior to the introduction of beta-adrenergic antagonists?

  1. Administering a beta-blocker first leaves alpha-adrenergic receptors unopposed, precipitating severe vasoconstriction, life-threatening hypertensive crisis, and acute pulmonary edema. Correct answer.
  2. Beta-blockers irreversibly inhibit catecholamine excretion by the renal tubules, leading to fatal catecholamine toxicity.
  3. Alpha-blockers are required to metabolize circulating metanephrines into harmless inactive peptides.
  4. Beta-blockade causes immediate desensitization of calcium channels, preventing anaesthetic induction.

Explanation

In patients with pheochromocytoma, circulating levels of norepinephrine and epinephrine are massively elevated. If a beta-blocker (e.g., propranolol, atenolol) is administered without adequate prior alpha-adrenergic blockade, beta-2 mediated skeletal muscle vasodilation is abolished while alpha-1 mediated vasoconstriction remains uninhibited. This 'unopposed alpha-stimulation' causes catastrophic systemic vasoconstriction, extreme surges in systemic vascular resistance, severe hypertensive crisis, myocardial infarction, and acute left ventricular failure with pulmonary edema. Clinical guidelines require alpha-blockade (phenoxybenzamine or doxazosin) for at least 10–14 days with fluid expansion before introducing a beta-blocker (which is added only if tachycardia or arrhythmias persist).

Question 45Perioperative assessment, regional anatomy and pain

What are the characteristic cardiopulmonary physiological consequences of carbon dioxide pneumoperitoneum (intra-abdominal pressure 12 to 15 mmHg) combined with steep Trendelenburg positioning during laparoscopic pelvic surgery?

  1. Increased systemic vascular resistance (SVR), decreased pulmonary compliance, decreased functional residual capacity (FRC), cephalad diaphragmatic shift, and elevated risk of hypercapnia and endobronchial intubation. Correct answer.
  2. Massive reduction in SVR, doubled lung compliance, and profound respiratory alkalosis.
  3. Complete elimination of venous return resulting in permanent asystole in all patients.
  4. Expansion of FRC above total lung capacity with rapid reduction in airway pressures.

Explanation

Laparoscopic peritoneal insufflation with carbon dioxide to 12–15 mmHg increases intra-abdominal pressure, compressing the abdominal aorta and triggering neurohumoral release (vasopressin, renin-angiotensin), which causes a marked rise in Systemic Vascular Resistance (SVR) and afterload. Concurrently, steep Trendelenburg pushes abdominal viscera against the diaphragm, shifting it cephalad, which reduces functional residual capacity (FRC) by up to 50%, decreases thoraco-pulmonary compliance, increases peak inspiratory pressure, and predisposes to atelectasis. Transperitoneal absorption of CO2 requires increased minute ventilation to avoid hypercapnia and acidosis. Furthermore, the cephalad diaphragmatic shift can migrate the carina relative to the endotracheal tube, predisposing to inadvertent right endobronchial intubation.

Question 46Perioperative assessment, regional anatomy and pain

Which set of cardiopulmonary and pharmacological changes correctly describes the maternal physiological adaptations to term pregnancy?

  1. Decreased cardiac output, increased functional residual capacity (FRC), decreased minute ventilation, and 50% increase in volatile anaesthetic MAC.
  2. Cardiac output increases by 40 to 50%, FRC decreases by 20 to 30%, minute ventilation increases by 40 to 50% (physiologic respiratory alkalosis), and volatile anaesthetic MAC decreases by 30 to 40%. Correct answer.
  3. Blood volume decreases by 20%, serum cholinesterase activity increases fivefold, and gastric emptying of solids is accelerated.
  4. Systemic vascular resistance increases twofold, maternal PaCO2 rises to 50 mmHg, and oxygen consumption decreases by 30%.

Explanation

During pregnancy, maternal physiology undergoes profound adaptations: (1) Cardiovascular: plasma volume increases by ~45% and RBC mass by ~30% (physiologic dilutional anemia); cardiac output increases by 40–50% due to increased stroke volume and heart rate; systemic vascular resistance decreases; (2) Respiratory: minute ventilation increases by 40–50% primarily via increased tidal volume (driven by progesterone stimulation of respiratory centers), producing a physiologic compensated respiratory alkalosis (normal maternal PaCO2 is ~30 mmHg / 4.0 kPa, with serum HCO3- ~20 mmol/L); Functional Residual Capacity (FRC) decreases by 20–30% due to diaphragmatic elevation by the gravid uterus; (3) Metabolism & Pharmacodynamics: oxygen consumption increases by 30–50% (leading to rapid desaturation during apnoea), and Minimum Alveolar Concentration (MAC) of volatile anaesthetics decreases by 30–40% due to progesterone and endorphins.

Question 47Perioperative assessment, regional anatomy and pain

What is the primary clinical and pharmacological rationale for using ultra-low-concentration local anaesthetics combined with lipophilic opioids (e.g., bupivacaine 0.0625%–0.1% or ropivacaine 0.1% with sufentanil/fentanyl) in modern epidural labor analgesia?

  1. To provide excellent dynamic sensory analgesia while preserving maternal motor function, facilitating mobility, and reducing instrumental vaginal delivery rates. Correct answer.
  2. To induce dense motor blockade of the lower extremities to keep the mother immobilized.
  3. To produce profound maternal somnolence and prevent active maternal pushing during the second stage.
  4. To permanently ablate sympathetic tone to induce therapeutic maternal hypotension.

Explanation

Modern obstetric anaesthesia guidelines (ČSARIM, ESAIC, SOAP) recommend low-dose or ultra-low-dose local anaesthetic epidural regimens (e.g., bupivacaine 0.0625%–0.1% or ropivacaine 0.1%–0.15% combined with sufentanil 0.5–1 ug/mL or fentanyl 2 ug/mL) administered via patient-controlled epidural analgesia (PCEA) or programmed intermittent epidural bolus (PIEB). The synergistic combination provides excellent visceral analgesia (blocking thin A-delta and C nociceptive fibers) while sparing larger motor fibers (A-alpha). This preserves maternal motor power ('walking epidural'), enhances satisfaction, and significantly reduces the incidence of instrumental assisted vaginal delivery compared to older high-concentration motor-blocking regimens.

Question 48Perioperative assessment, regional anatomy and pain

A healthy 30-year-old primigravida receives spinal anaesthesia with hyperbaric bupivacaine for an elective Cesarean section. Which vasopressor is recommended as the first-line agent of choice to prevent and treat spinal-induced maternal hypotension?

  1. Ephedrine boluses exclusively, because ephedrine is the only agent that preserves uterine blood flow.
  2. High-dose dopamine infusion (20 ug/kg/min) titrated to achieve maternal heart rate > 130 bpm.
  3. Phenylephrine (titrated as a prophylactic variable-rate infusion or intermittent boluses), which maintains maternal blood pressure with less fetal acidosis compared to ephedrine. Correct answer.
  4. Isoproterenol infusion titrated to maintain maternal diastolic pressure < 40 mmHg.

Explanation

Extensive randomized controlled trials and international consensus guidelines establish phenylephrine as the frontline vasopressor of choice for preventing and treating spinal-induced hypotension during Cesarean delivery. Phenylephrine is a pure alpha-1 adrenergic agonist that restores systemic vascular resistance without significant transplacental metabolic stimulation. In contrast, ephedrine readily crosses the placenta and stimulates fetal beta-adrenergic receptors, accelerating fetal metabolism and carbon dioxide production, which leads to lower umbilical artery pH (fetal acidosis). Prophylactic phenylephrine infusion (e.g., 25–50 ug/min) maintains maternal cardiac output and superior neonatal acid-base status.

Question 49Perioperative assessment, regional anatomy and pain

In the pharmacological management of severe Postpartum Hemorrhage (PPH) caused by uterine atony refractory to oxytocin infusion, which second-line uterotonic agent is strictly contraindicated in a parturient with severe preeclampsia and arterial hypertension?

  1. Methylergometrine (an ergot alkaloid that causes intense generalized arterial vasoconstriction). Correct answer.
  2. Tranexamic acid (an antifibrinolytic lysine derivative).
  3. Carboprost tromethamine (prostaglandin F2-alpha).
  4. Misoprostol (a prostaglandin E1 analogue administered sublingually or rectally).

Explanation

Methylergometrine (Methergine) is a potent ergot alkaloid that stimulates smooth muscle contraction of both the myometrium and systemic blood vessels by alpha-adrenergic and serotonergic mechanisms. Because it induces intense, generalized arterial vasoconstriction, it can trigger catastrophic spikes in blood pressure, hypertensive encephalopathy, intracerebral hemorrhage, acute myocardial infarction, and pulmonary edema in patients with preeclampsia, chronic hypertension, or coronary artery disease; it is strictly contraindicated in these populations. In contrast, Carboprost (PGF2-alpha) causes bronchoconstriction and is contraindicated in severe asthma, while Tranexamic acid and Misoprostol (PGE1) can be safely used in hypertensive parturients.

Question 50Perioperative assessment, regional anatomy and pain

A 5-week-old male infant with Infantile Hypertrophic Pyloric Stenosis presents with persistent non-bilious projectile vomiting. Why is pyloromyotomy considered a medical rather than a surgical emergency, and what specific biochemical criteria must be fulfilled prior to anaesthesia?

  1. Surgery must be delayed until fluid and electrolyte resuscitation corrects the hypochloremic, hypokalemic metabolic alkalosis (chloride > 100 mmol/L, potassium > 3.5 mmol/L, HCO3- < 30 mmol/L) to prevent fatal intraoperative arrhythmias and central postoperative apnoea. Correct answer.
  2. Surgery must be performed within 30 minutes of arrival regardless of electrolytes to prevent bowel perforation.
  3. The metabolic derangement is hyperchloremic metabolic acidosis with severe hyperkalemia; infuse potassium-free saline.
  4. Surgery must be delayed for 6 weeks until the hypertrophied pyloric muscle spontaneously regresses.

Explanation

Hypertrophic pyloric stenosis is a MEDICAL resuscitation emergency, NOT a surgical emergency. Persistent vomiting of gastric hydrochloric acid and potassium results in dehydration, hypochloremia, hypokalemia, and metabolic alkalosis. As volume depletion activates the renin-angiotensin-aldosterone system, the kidneys conserve sodium at the expense of potassium and hydrogen ion excretion in the distal tubules, leading to the pathognomonic finding of 'paradoxical aciduria' in the setting of severe systemic alkalosis. Inducing anaesthesia in an alkalotic, dehydrated infant carries an unacceptably high risk of hypovolemic collapse, lethal cardiac arrhythmias, and prolonged postoperative central apnoea (CSF alkalosis suppresses central respiratory drive). Resuscitation with 0.9% normal saline with KCl must restore serum chloride > 100 mmol/L, potassium > 3.5 mmol/L, and HCO3- < 30 mmol/L with adequate urine output before surgery.