I85PREP
⌘ K
Facharzt FMH Anästhesiologie - independent subject foundations study materials
Facharzt FMH Anästhesiologie - independent subject foundations study resources

Facharzt FMH Anästhesiologie - independent subject foundations practice questions

One question at a time. Build your Facharzt FMH Anästhesiologie - independent subject foundations understanding.

First 50 of 190 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Anesthesia pharmacology and physiological mechanisms

A 45-year-old patient is undergoing general anesthesia maintained with desflurane in an oxygen/air mixture. Which of the following physical and pharmacological properties is characteristic of desflurane compared to sevoflurane and isoflurane?

  1. Lowest blood:gas partition coefficient (~0.42), resulting in the fastest alveolar wash-in and wash-out kinetics Correct answer.
  2. Highest oil:gas partition coefficient, resulting in the lowest minimum alveolar concentration (MAC)
  3. High boiling point of 58.5°C, allowing administration through standard unheated tec vaporizers
  4. Absence of airway irritation when administered in high concentrations during mask induction

Explanation

Desflurane has a very low blood:gas partition coefficient of approximately 0.42 (compared to ~0.65 for sevoflurane and ~1.4 for isoflurane), which confers rapid induction and emergence kinetics. Because of its high vapor pressure and boiling point near room temperature (22.8°C), desflurane requires a specialized heated, pressurized vaporizer (Tec 6 / D-Vapor). It is pungent and causes airway irritation, making it unsuitable for inhalational induction.

Question 2Anesthesia pharmacology and physiological mechanisms

A 58-year-old male with severe ischemic cardiomyopathy (LVEF 22%) presents for urgent bowel obstruction repair. The anesthesiologist selects etomidate for induction of general anesthesia. What is the primary endocrine consideration associated with even a single induction dose of etomidate?

  1. Immediate suppression of thyroid-stimulating hormone (TSH) secretion lasting 48 hours
  2. Reversible inhibition of 11-beta-hydroxylase, leading to transient adrenocortical suppression Correct answer.
  3. Profound stimulation of aldosterone synthase, causing acute hyperkalemia and metabolic acidosis
  4. Irreversible destruction of the adrenal cortex, requiring lifelong mineralocorticoid replacement

Explanation

Etomidate is an imidazole derivative that provides exceptional cardiovascular stability but causes dose-dependent, reversible inhibition of 11-beta-hydroxylase (the enzyme converting 11-deoxycortisol to cortisol and 11-deoxycorticosterone to corticosterone). A single induction dose can suppress the adrenocortical stress response for 6 to 24 hours.

Question 3Anesthesia pharmacology and physiological mechanisms

A 32-year-old patient undergoing knee arthroscopy receives an ultrasound-guided femoral nerve block with 20 mL of 0.5% bupivacaine. Five minutes after injection, the patient develops perioral numbness, metallic taste, sudden generalized tonic-clonic seizures, and wide-complex ventricular tachycardia. Which molecular mechanism explains the heightened cardiotoxicity of bupivacaine compared to lidocaine?

  1. Selective blockade of L-type calcium channels without affecting myocardial sodium conduction
  2. Rapid dissociation from open voltage-gated potassium channels during the cardiac action potential
  3. Selective agonism of central alpha-2 adrenoceptors causing massive sympathetic outflow
  4. Slow dissociation kinetics from cardiac voltage-gated sodium channels during diastole ('fast-in, slow-out') Correct answer.

Explanation

Bupivacaine is highly lipid-soluble and binds avidly to inactivated/open myocardial voltage-gated sodium channels (Nav1.5). Unlike lidocaine, which dissociates rapidly during diastole ('fast-in, fast-out'), bupivacaine exhibits 'fast-in, slow-out' kinetics, remaining bound during diastole. This leads to profound conduction slowing, refractory re-entrant ventricular arrhythmias, electromechanical dissociation, and decreased myocardial contractility.

Question 4Anesthesia pharmacology and physiological mechanisms

A continuous target-controlled infusion (TCI) of remifentanil is administered during a 6-hour craniotomy. Why does remifentanil maintain a virtually constant context-sensitive half-time of 3 to 5 minutes regardless of the duration of infusion?

  1. Rapid metabolism via non-specific esterases in blood and tissues into a weakly active metabolite Correct answer.
  2. Extensive pulmonary first-pass uptake followed by rapid renal excretion unchanged in urine
  3. Ultra-fast hepatic clearance mediated exclusively by cytochrome P450 CYP3A4 enzymes
  4. Immediate irreversible binding to plasma alpha-1-acid glycoprotein preventing tissue accumulation

Explanation

Remifentanil contains a methyl ester linkage that makes it susceptible to rapid hydrolysis by non-specific plasma and tissue esterases to remifentanil acid, which possesses 1/4600th the potency of the parent drug. Because it is not reliant on organ-dependent clearance (hepatic or renal) or redistribution for offset, its context-sensitive half-time remains 3–5 minutes even after prolonged infusions.

Question 5Anesthesia pharmacology and physiological mechanisms

A 24-year-old trauma patient with an acute open femur fracture is scheduled for emergency surgery. He ate a large meal 1 hour prior to the accident. Rapid sequence induction (RSI) is planned. Why is succinylcholine contraindicated in a patient with a known history of malignant hyperthermia?

  1. It causes profound histamine release leading to unmanageable bronchospasm
  2. It binds to plasma pseudocholinesterase, depleting circulating enzyme stores
  3. It competitively inhibits non-depolarizing relaxants, preventing airway protection
  4. It acts as a potent triggering agent causing sustained calcium release from the sarcoplasmic reticulum Correct answer.

Explanation

Succinylcholine and all volatile inhalational anesthetics (sevoflurane, desflurane, isoflurane) are absolute triggers of malignant hyperthermia (MH). In MH-susceptible individuals harboring mutations in the RYR1 or CACNA1S genes, these agents trigger uncontrolled intracellular calcium release from the sarcoplasmic reticulum, causing hypermetabolism, sustained muscle rigidity, and rhabdomyolysis.

Question 6Anesthesia pharmacology and physiological mechanisms

A 42-year-old woman undergoing total intravenous anesthesia (TIVA) with propofol and remifentanil receives a continuous infusion of propofol for 5 hours. Which pharmacokinetic model parameter dictates the prolonged recovery time after discontinuation of a long propofol infusion compared to a short 30-minute bolus case?

  1. Context-sensitive half-time, which increases with infusion duration due to cumulative saturation of peripheral fat compartments Correct answer.
  2. Elimination half-life (t1/2 beta), which remains fixed at 2 minutes regardless of duration
  3. Clearance rate, which decreases exponentially as hepatic blood flow increases
  4. Central compartment volume (V1), which expands tenfold during steady-state anesthesia

Explanation

The context-sensitive half-time is the time required for the central compartment drug concentration to decrease by 50% after stopping a steady-state infusion of a given duration ('context'). For propofol, as the infusion duration extends to multiple hours, peripheral compartments (muscle and fat) fill, decreasing the net concentration gradient from blood to tissues, which prolongs the context-sensitive half-time.

Question 7Anesthesia pharmacology and physiological mechanisms

Which physicochemical property of a local anesthetic agent is the primary determinant of its onset of action?

  1. Lipid solubility (octanol:water partition coefficient)
  2. Acid dissociation constant (pKa) relative to physiological tissue pH (7.4) Correct answer.
  3. Plasma protein binding percentage (alpha-1-acid glycoprotein)
  4. Molecular weight and chemical linkage (ester vs amide)

Explanation

The pKa of a local anesthetic determines the proportion of the drug that exists in the uncharged (non-ionized, lipid-soluble base) form at physiological pH (7.4) according to the Henderson-Hasselbalch equation. Only the uncharged base form can penetrate the neural lipid membrane to reach the intracellular receptor site; therefore, agents with a pKa closer to 7.4 (e.g., lidocaine pKa 7.9) have a faster onset of action than agents with higher pKa (e.g., bupivacaine pKa 8.1).

Question 8Anesthesia pharmacology and physiological mechanisms

A 30-year-old woman with severe postpartum hemorrhage undergoes emergency laparotomy. The anesthesiologist administers tranexamic acid (TXA) as an antifibrinolytic bolus. What is the molecular mechanism of action of tranexamic acid?

  1. Direct inhibition of factor Xa in the prothrombinase complex
  2. Neutralization of tissue factor pathway inhibitor (TFPI)
  3. Inhibition of antithrombin III activation on endothelial surfaces
  4. Competitive reversible blockade of lysine-binding sites on plasminogen and plasmin Correct answer.

Explanation

Tranexamic acid is a synthetic lysine analogue that competitively binds to the lysine-binding sites of plasminogen and plasmin, preventing their interaction with and degradation of fibrin. This stabilizes clot structure and reduces hyperfibrinolysis-induced surgical hemorrhage.

Question 9Anesthesia pharmacology and physiological mechanisms

A 62-year-old patient undergoing prolonged major pelvic exenteration receives a continuous infusion of cisatracurium. What is the metabolic pathway responsible for the termination of action of cisatracurium?

  1. Hofmann elimination (spontaneous non-enzymatic chemical breakdown at physiological pH and temperature) and non-specific ester hydrolysis Correct answer.
  2. Rapid metabolism by butyrylcholinesterase (pseudocholinesterase) in circulating plasma
  3. Hepatic glucuronidation via UDP-glucuronosyltransferase 1A1 (UGT1A1) followed by biliary excretion
  4. Renal tubular active transport secretion of unchanged quaternary ammonium ions

Explanation

Cisatracurium (an isomer of atracurium) undergoes organ-independent degradation primarily via Hofmann elimination-a spontaneous temperature- and pH-dependent non-enzymatic chemical process-and to a lesser degree by non-specific plasma esterases. Its clearance is therefore unaltered in severe renal or hepatic failure.

Question 10Anesthesia pharmacology and physiological mechanisms

A 52-year-old patient is receiving dexmedetomidine as an anesthetic adjuvant for awake fiberoptic intubation. Which physiological and pharmacological characteristic is uniquely observed with dexmedetomidine?

  1. Potent respiratory depression with blunted hypercapnic ventilatory drive
  2. Irreversible blockade of GABA-A receptors producing emergence delirium
  3. Cooperative sedation with minimal respiratory depression via central alpha-2A adrenoceptor agonism in the locus coeruleus Correct answer.
  4. Profound tachycardia and hypertensive crisis due to selective peripheral vasodilation

Explanation

Dexmedetomidine is a potent, highly selective alpha-2 adrenoceptor agonist (alpha-2:alpha-1 ratio of 1600:1) that acts centrally in the locus coeruleus to produce 'cooperative' or 'conscious' sedation mimicking non-REM sleep, with negligible depression of respiratory drive. Common side effects include dose-dependent bradycardia and hypotension (or transient hypertension with rapid boluses via peripheral alpha-2B receptors).

Question 11Anesthesia pharmacology and physiological mechanisms

Which of the following factors decreases the Minimum Alveolar Concentration (MAC) of volatile inhalational anesthetics?

  1. Hyperthermia (temperature >39°C)
  2. Chronic alcohol abuse
  3. Hypernatremia
  4. Advanced age, acute alcohol intoxication, and pregnancy Correct answer.

Explanation

MAC decreases (meaning less volatile anesthetic is required) with advanced age (decreases ~6% per decade after 40), hypothermia, acute alcohol intoxication, pregnancy (due to progesterone and endorphins), hypoxemia, hypotension, and co-administration of opioids or alpha-2 agonists. Factors that increase MAC include hyperthermia, hypernatremia, chronic alcohol abuse, and acute amphetamine/cocaine use.

Question 12Anesthesia pharmacology and physiological mechanisms

A 28-year-old male receives 100 mg of succinylcholine for emergency intubation. After 30 minutes, he remains completely paralyzed with no twitches on train-of-four monitoring. A dibucaine number test is ordered postoperatively. What does a dibucaine number of 20 indicate?

  1. Homozygous atypical pseudocholinesterase (butyrylcholinesterase deficiency), causing prolonged neuromuscular blockade for several hours Correct answer.
  2. Normal pseudocholinesterase activity with normal enzyme concentration
  3. Heterozygous atypical pseudocholinesterase with mild block prolongation of 20–30 minutes
  4. Hyperactive plasma cholinesterase causing accelerated succinylcholine resistance

Explanation

Dibucaine is an amide local anesthetic that inhibits normal plasma pseudocholinesterase (butyrylcholinesterase) by ~80% (dibucaine number ~80). Heterozygotes for the atypical allele show ~50–60% inhibition, while homozygous atypical individuals have a dibucaine number of ~20. In homozygous atypical patients, succinylcholine is not hydrolyzed normally and the resulting phase I block can persist for 4 to 8 hours until eliminated by other minor pathways.

Question 13Anesthesia pharmacology and physiological mechanisms

A 50-year-old patient receives an intravenous bolus of ketamine for procedural sedation. Which receptor interaction is primarily responsible for the dissociative anesthesia and analgesic properties of ketamine?

  1. Positive allosteric modulation of the GABA-A receptor complex
  2. Non-competitive antagonism of the N-methyl-D-aspartate (NMDA) receptor phencyclidine binding site Correct answer.
  3. Direct selective stimulation of mu-opioid receptor heterodimers
  4. Inhibition of the glycine receptor chloride channel pore

Explanation

Ketamine produces dissociative anesthesia, intense analgesia, and amnesia primarily through non-competitive antagonism of the NMDA receptor complex by binding to the phencyclidine site within the ion channel pore, thereby inhibiting excitatory glutamate transmission. It also interacts weakly with opioid, cholinergic, and monoaminergic systems.

Question 14Anesthesia pharmacology and physiological mechanisms

What is the primary mechanism of action of neostigmine when used for the reversal of non-depolarizing neuromuscular blockade?

  1. Direct competitive displacement of rocuronium from postjunctional nicotinic receptors
  2. Chemical encapsulation and sequestration of steroidal neuromuscular blockers in plasma
  3. Reversible inhibition of acetylcholinesterase, increasing acetylcholine concentration in the synaptic cleft Correct answer.
  4. Opening of voltage-gated presynaptic calcium channels to promote massive acetylcholine vesicle exocytosis

Explanation

Neostigmine is a carbamate quaternary amine that reversibly inhibits acetylcholinesterase (and pseudocholinesterase) by forming a carbamylated enzyme complex. This prevents the breakdown of acetylcholine, increasing its concentration at the neuromuscular junction to competitively displace non-depolarizing neuromuscular blocking agents from postjunctional nicotinic receptors. It must be co-administered with an anticholinergic (glycopyrrolate or atropine) to prevent muscarinic side effects (bradycardia, bronchospasm, salivation).

Question 15Anesthesia pharmacology and physiological mechanisms

A patient scheduled for total hip arthroplasty receives a spinal anesthetic containing 15 mg of hyperbaric bupivacaine 0.5% in 8% glucose. What is the physical definition of a hyperbaric local anesthetic solution?

  1. The solution has a specific gravity (density) greater than that of normal human cerebrospinal fluid (~1.006–1.008 g/mL) Correct answer.
  2. The solution has an osmolarity exceeding 1200 mOsm/L regardless of density
  3. The solution has a lower barometric pressure than ambient operating room atmosphere
  4. The solution is mixed with heavy lipid micelles to prevent rostral spreading

Explanation

A hyperbaric local anesthetic solution has a specific gravity/density greater than that of human cerebrospinal fluid (normal CSF density at 37°C is 1.0063–1.0075 g/mL). By adding dextrose/glucose, the density is increased (>1.020 g/mL), allowing predictable spread under the influence of gravity according to patient positioning.

Question 16Anesthesia pharmacology and physiological mechanisms

A 65-year-old man with severe liver cirrhosis (Child-Pugh Class C) is scheduled for umbilical hernia repair. Which of the following pharmacokinetic alterations is most likely observed regarding intravenous anesthetic agents in this patient?

  1. Decreased volume of distribution for hydrophilic drugs due to ascites
  2. Increased free (unbound) fraction of highly protein-bound drugs (e.g., rocuronium, diazepam) due to hypoalbuminemia Correct answer.
  3. Accelerated hepatic clearance of high-extraction ratio drugs due to portosystemic shunting
  4. Decreased elimination half-life of steroidal neuromuscular blockers

Explanation

In severe liver cirrhosis, reduced hepatic synthesis of albumin decreases plasma protein binding, leading to an increased free (active) fraction of drugs. Additionally, ascites and fluid retention expand the volume of distribution (Vd) for both hydrophilic and lipophilic drugs, requiring larger initial loading doses of neuromuscular blockers (like rocuronium), but impaired hepatic clearance and biliary excretion significantly prolong their elimination half-lives and duration of action.

Question 17Anesthesia pharmacology and physiological mechanisms

A 29-year-old primigravida at 39 weeks of gestation requests labor epidural analgesia. Following an uneventful epidural placement at L3-L4, which of the following physiological changes occurs during normal pregnancy that increases sensitivity to neuraxial local anesthetics?

  1. Decreased cerebrospinal fluid protein concentration causing accelerated enzymatic degradation
  2. Increased epidural space volume due to lumbar lordosis
  3. Engorgement of epidural venous plexuses (Batson's plexus) reducing subarachnoid/epidural space volume, combined with progesterone-mediated neural sensitivity Correct answer.
  4. Increased cerebrospinal fluid volume by 50% requiring double the standard local anesthetic dose

Explanation

During pregnancy, inferior vena cava compression by the gravid uterus diverts venous return through the vertebral venous plexus (Batson's plexus), engorging epidural veins and reducing both epidural and subarachnoid space volumes. Furthermore, elevated progesterone levels enhance the sensitivity of neural membranes to local anesthetics, reducing local anesthetic requirements for spinal and epidural anesthesia by approximately 25–30%.

Question 18Anesthesia pharmacology and physiological mechanisms

A 72-year-old patient with non-valvular atrial fibrillation taking dabigatran 150 mg twice daily suffers a traumatic intracranial hemorrhage requiring urgent neurosurgical evacuation. What is the specific monoclonal antibody fragment approved for immediate reversal of dabigatran?

  1. Andexanet alfa
  2. 4-Factor Prothrombin Complex Concentrate (4F-PCC)
  3. Protamine sulfate
  4. Idarucizumab Correct answer.

Explanation

Idarucizumab (Praxbind) is a humanized monoclonal antibody Fab fragment that binds specifically and with high affinity (350 times greater than thrombin) to free and thrombin-bound dabigatran, neutralizing its anticoagulant effect within minutes. The standard dose is 5 g IV (administered as two 2.5 g vials). Andexanet alfa is the reversal agent for direct factor Xa inhibitors (apixaban, rivaroxaban).

Question 19Airway assessment, respiratory mechanics and ventilation

A 66-year-old male with chronic obstructive pulmonary disease (COPD) undergoes thoracoscopic wedge resection. Hypoxic pulmonary vasoconstriction (HPV) is essential to preserve arterial oxygenation during one-lung ventilation. Which factor significantly inhibits HPV and worsens intrapulmonary shunt during thoracic anesthesia?

  1. Mild respiratory acidosis (arterial pH 7.30)
  2. Moderate hypercapnia (PaCO2 50 mmHg)
  3. High concentrations of volatile anesthetics (>1.0–1.5 MAC) Correct answer.
  4. Intravenous administration of propofol at standard TIVA rates

Explanation

Hypoxic pulmonary vasoconstriction (HPV) diverts blood flow away from hypoxic, non-ventilated lung regions toward well-ventilated regions. Inhalational volatile anesthetics (sevoflurane, isoflurane, desflurane) produce dose-dependent inhibition of HPV when administered at concentrations >1.0 MAC, exacerbating venous admixture (shunt). Intravenous anesthetics such as propofol do not inhibit HPV.

Question 20Airway assessment, respiratory mechanics and ventilation

Which of the following anatomical characteristics distinguishes the infant airway from the adult airway?

  1. A relatively smaller tongue relative to the oral cavity
  2. A more cephalad larynx located at the level of C3–C4 (compared to C4–C5/C6 in adults), with a large, floppy, omega-shaped epiglottis Correct answer.
  3. The narrowest portion of the airway is located at the vocal cords rather than the cricoid ring
  4. A long, rigid trachea that resists dynamic collapse during inspiration

Explanation

The infant airway has distinct anatomical differences: the larynx is positioned more cephalad (at C3–C4 vs C4–C6 in adults), the tongue is relatively large, the occiput is prominent (causing neck flexion in the supine position), the epiglottis is long, floppy, and omega-shaped, the vocal cords slant anteroinferiorly, and the subglottic region at the non-distensible cricoid ring is the narrowest anatomical point (though functional narrowing at the vocal cords also occurs).

Question 21Airway assessment, respiratory mechanics and ventilation

A 3-year-old child undergoing strabismus surgery develops sudden inspiratory stridor, complete cessation of air movement, chest wall retractions, and desaturation to 78% immediately following tracheal extubation in a light plane of anesthesia. What is the immediate first-line management step for severe pediatric laryngospasm?

  1. Immediate oral administration of nebulized budesonide and chest physiotherapy
  2. Urgent emergency front-of-neck surgical cricothyroidotomy
  3. 100% oxygen with continuous positive airway pressure (CPAP), gentle jaw thrust with Larson's maneuver (pressure at the laryngospasm notch), followed by low-dose IV propofol or succinylcholine if unresolved Correct answer.
  4. High-dose intravenous atropine 0.04 mg/kg as sole therapy to dry airway secretions

Explanation

Severe laryngospasm is a closure of the glottis due to reflex adductor spasm. Immediate treatment consists of applying 100% FiO2 with a tight mask seal and continuous positive airway pressure (CPAP), performing a vigorous jaw thrust with bilateral pressure at Larson's notch (behind the condyle of the mandible and anterior to the mastoid process). If spasm persists and desaturation worsens, administer low-dose IV propofol (0.5–1 mg/kg) or IV succinylcholine (0.5–1 mg/kg with atropine 0.02 mg/kg to prevent bradycardia) or IM succinylcholine (3–4 mg/kg).

Question 22Airway assessment, respiratory mechanics and ventilation

What is the primary distinguishing design feature of a second-generation supraglottic airway device (SAD, such as the LMA ProSeal, LMA Supreme, or i-gel) compared to a first-generation device (classic LMA)?

  1. Made of stainless steel to prevent compression by teeth
  2. Incorporates a radio-opaque marker for continuous fluoroscopic visualization
  3. Operates without any airway seal pressure threshold
  4. Features a dedicated gastric drainage channel to vent stomach contents and provides higher oropharyngeal seal pressures (>25–30 cmH2O) Correct answer.

Explanation

Second-generation supraglottic airway devices (SADs) are specifically designed with: 1) a separate gastric drainage channel allowing decompression of the stomach and venting of regurgitated gastric fluid away from the laryngeal inlet, 2) higher seal pressures (>25–30 cmH2O), and 3) built-in bite blocks. They offer enhanced safety against pulmonary aspiration compared to first-generation SADs.

Question 23Airway assessment, respiratory mechanics and ventilation

During elective surgery in a 60-year-old male under general anesthesia, the patient suddenly exhibits sudden peak airway pressure elevation (from 18 to 44 cmH2O), loss of chest expansion, severe expiratory wheezing on auscultation, and a delayed 'shark-fin' upstroke on the capnography waveform. What is the diagnosis and immediate management?

  1. Severe acute intraoperative bronchospasm; deepen anesthesia (volatile agent/propofol/ketamine), deliver inhaled beta-2 agonist (salbutamol via ETT adapter), 100% O2, and give IV bronchodilators/steroids Correct answer.
  2. Endotracheal tube extubation; immediate re-intubation without medication
  3. Acute pulmonary embolism; immediate administration of intravenous heparin 5000 IU
  4. Tension pneumothorax; immediate bilateral surgical thoracotomy

Explanation

Intraoperative bronchospasm causes marked expiratory airway resistance, resulting in elevated peak inspiratory pressure, prolonged expiration, expiratory wheezing, and the pathognomonic 'shark-fin' capnography waveform (delayed alveolar emptying). Immediate management includes: 100% O2, deepening anesthesia with a volatile anesthetic (potent bronchodilators), propofol, or ketamine, administering inhaled beta-2 agonists (salbutamol/albuterol via in-line MDI adapter), IV magnesium sulfate (2 g), IV aminophylline or IV epinephrine if refractory, and checking for mechanical causes (carinal stimulation, kinked ETT).

Question 24Airway assessment, respiratory mechanics and ventilation

A 68-year-old female undergoes awake fiberoptic intubation due to severe ankylosing spondylitis and a fixed, flexed cervical spine. Which local anesthetic nerve block technique provides sensory topicalization to the anterior two-thirds of the tongue and the posterior pharyngeal wall?

  1. Recurrent laryngeal nerve block at the cricothyroid membrane
  2. Glossopharyngeal nerve block at the base of the palatoglossal arch combined with topical lidocaine spray to the oral cavity Correct answer.
  3. Superior laryngeal nerve block at the level of the clavicle
  4. Phrenic nerve block at the interscalene groove

Explanation

The glossopharyngeal nerve (CN IX) provides sensory innervation to the posterior third of the tongue, the palatine tonsils, vallecula, anterior surface of the epiglottis, and the posterior pharyngeal wall (afferent limb of the gag reflex). It can be blocked by injecting 1–2 mL of 2% lidocaine submucosally at the base of the palatoglossal arch (or via topicalization). The internal branch of the superior laryngeal nerve (CN X) innervates the larynx down to the vocal cords, and the recurrent laryngeal nerve innervates subglottic mucosa.

Question 25Airway assessment, respiratory mechanics and ventilation

During cardiac arrest in the operating room under general anesthesia, what is the recommended chest compression rate, compression depth, and ventilation protocol according to current ERC/AHA Advanced Life Support (ALS) guidelines once an endotracheal tube is secured?

  1. 80 compressions/min, depth 2 cm, stop compressions for 2 breaths every 15 compressions
  2. 140 compressions/min, depth 8 cm, continuous hyperventilation at 30 breaths/min
  3. 100–120 compressions/min, depth 5–6 cm, continuous unbroken chest compressions with asynchronous ventilations at 10 breaths/min (1 breath every 6 seconds) with 100% FiO2 Correct answer.
  4. 60 compressions/min, depth 3 cm, synchronized breaths after every single compression

Explanation

According to ERC and AHA guidelines, once an advanced airway (ETT or supraglottic airway) is placed during CPR, rescuers should deliver continuous chest compressions at a rate of 100–120/min and a depth of 5–6 cm without pausing for ventilations. Ventilations are delivered asynchronously at a rate of 10 breaths/min (1 breath every 6 seconds) with 100% oxygen, avoiding hyperventilation which increases intrathoracic pressure and impedes venous return.

Question 26Airway assessment, respiratory mechanics and ventilation

An anesthesiologist is evaluating a patient with a predicted difficult airway. Which of the following combinations of physical examination findings is most strongly predictive of difficult direct laryngoscopy and intubation?

  1. Mallampati Class I, thyromental distance >7 cm, inter-incisor gap >4.5 cm
  2. Mallampati Class IV, thyromental distance <6 cm, inter-incisor mouth opening <3 cm, sternomental distance <12.5 cm, and limited cervical spine extension (<35°) Correct answer.
  3. Normal upper lip bite test (Class 1), broad mandible, full range of neck movement
  4. Absence of teeth with normal mandibular protrusion

Explanation

No single physical airway test has high standalone sensitivity, but the combination of multiple abnormal parameters significantly increases the predictive value for difficult laryngoscopy: Mallampati Class III/IV (inability to see soft palate/uvula), reduced thyromental distance (<6 cm), reduced mouth opening (<3 cm / <2 fingerbreadths), sternomental distance <12.5 cm, limited neck extension, high upper lip bite test (Class 3), and retrognathia.

Question 27Airway assessment, respiratory mechanics and ventilation

A 40-year-old patient undergoing emergency appendectomy vomits large volumes of acidic gastric contents during induction prior to tracheal intubation. What immediate sequence of actions should the anesthesiologist perform to minimize pulmonary aspiration?

  1. Tilt the operating table head-down (Trendelenburg position), immediately suction the oropharynx and airway, insert a cuffed endotracheal tube, and suction the trachea before applying positive pressure ventilation Correct answer.
  2. Place the patient in a sitting position and apply high-pressure positive-pressure mask ventilation
  3. Administer 100 mg of IV succinylcholine and wait 5 minutes before suctioning
  4. Immediately perform emergency front-of-neck surgical cricothyroidotomy

Explanation

If active regurgitation/emesis occurs during induction: 1) immediately tilt the bed into the Trendelenburg (head-down) position and turn the head to the side (unless contraindicated by spine trauma) to direct vomitus away from the larynx by gravity, 2) perform aggressive rigid suction of the oropharynx, 3) intubate the trachea with a cuffed ETT and inflate the cuff, and 4) suction the endotracheal tube and lower airways before initiating positive-pressure ventilation to avoid pushing aspirated material deeper into the lungs.

Question 28Airway assessment, respiratory mechanics and ventilation

During elective direct laryngoscopy, the anesthesiologist visualizes only the epiglottis; the vocal cords and arytenoid cartilages cannot be seen. What Cormack-Lehane laryngoscopy grade does this represent?

  1. Grade 1
  2. Grade 2a
  3. Grade 4
  4. Grade 3 Correct answer.

Explanation

The Cormack-Lehane classification grades the laryngeal view during direct laryngoscopy: Grade 1 = full view of the glottis and vocal cords; Grade 2 = partial view of the glottis (2a: posterior glottic cords visible, 2b: only arytenoid cartilages visible); Grade 3 = only the epiglottis is visible (no glottic structures); Grade 4 = neither epiglottis nor glottis is visible (only soft palate).

Question 29Airway assessment, respiratory mechanics and ventilation

A 58-year-old male with severe acute pancreatitis in the ICU develops acute respiratory failure. Chest radiography shows bilateral diffuse pulmonary infiltrates, and the arterial blood gas on 100% FiO2 with a PEEP of 12 cmH2O reveals a PaO2 of 72 mmHg (PaO2/FiO2 ratio = 72 mmHg). According to the Berlin definition, what is the diagnosis and severity of this condition?

  1. Severe Acute Respiratory Distress Syndrome (severe ARDS, PaO2/FiO2 ≤100 mmHg with PEEP ≥5 cmH2O) Correct answer.
  2. Mild ARDS (PaO2/FiO2 201–300 mmHg)
  3. Moderate ARDS (PaO2/FiO2 101–200 mmHg)
  4. Cardiogenic pulmonary edema

Explanation

According to the Berlin definition, ARDS is classified by the PaO2/FiO2 (P/F) ratio on PEEP ≥5 cmH2O occurring within 1 week of a known clinical insult with bilateral opacities not fully explained by cardiac failure: Mild ARDS = P/F ratio 201–300 mmHg; Moderate ARDS = P/F ratio 101–200 mmHg; Severe ARDS = P/F ratio ≤100 mmHg. Here, P/F = 72 mmHg, which meets the criteria for severe ARDS.

Question 30Airway assessment, respiratory mechanics and ventilation

A 62-year-old intubated patient with severe ARDS (PaO2/FiO2 ratio = 95 mmHg on FiO2 0.8 and PEEP 14 cmH2O) has been mechanically ventilated for 16 hours. According to the PROSEVA trial and international ARDS guidelines, what intervention significantly improves 28-day and 90-day survival?

  1. Immediate tracheostomy and spontaneous breathing trials
  2. High-dose intravenous loop diuretics to produce 5 liters of negative fluid balance per day
  3. Prone positioning ventilation for at least 16 consecutive hours per session Correct answer.
  4. Routine high-frequency oscillatory ventilation (HFOV)

Explanation

The PROSEVA trial demonstrated a significant reduction in 28-day and 90-day mortality in patients with severe ARDS (PaO2/FiO2 <150 mmHg) when placed in the prone position for at least 16 consecutive hours per day. Prone positioning promotes more homogeneous ventilation-perfusion matching, recruits dorsal lung regions, and reduces regional lung strain and stress.

Question 31Airway assessment, respiratory mechanics and ventilation

In patients with severe ARDS, how is the respiratory system 'driving pressure' calculated, and what threshold value is independently associated with increased hospital mortality?

  1. Driving Pressure = Peak Inspiratory Pressure / PEEP; threshold >3.0
  2. Driving Pressure = Mean Airway Pressure - AutoPEEP; threshold >25 cmH2O
  3. Driving Pressure = End-Expiratory Lung Volume / Compliance; threshold >50 mL
  4. Driving Pressure = Plateau Pressure (Pplat) - PEEP; threshold >14–15 cmH2O Correct answer.

Explanation

Driving pressure (ΔP) is calculated as Plateau Pressure minus Positive End-Expiratory Pressure (ΔP = Pplat - PEEP) during an end-inspiratory and end-expiratory pause without spontaneous effort. It represents the ratio of tidal volume to respiratory system compliance (ΔP = VT / Crs). Landmark studies (Amato et al.) identified that a driving pressure >14–15 cmH2O is strongly and independently associated with increased mortality in mechanically ventilated ARDS patients.

Question 32Hemodynamic monitoring, shock and circulation

An anesthesiologist prepares to induce anesthesia in a 74-year-old patient with known severe aortic valve stenosis (valve area 0.7 cm², mean gradient 48 mmHg). What are the key hemodynamic management goals for this patient?

  1. Tachycardia (heart rate >110 bpm) and low systemic vascular resistance to reduce afterload
  2. Maintain normal sinus rhythm, preserve adequate preload, avoid tachycardia, and maintain high/normal systemic vascular resistance Correct answer.
  3. Induce marked vasodilation using high-dose nitroglycerin to optimize stroke volume
  4. Maintain wide pulse pressure with permissive systemic hypotension to reduce myocardial oxygen demand

Explanation

In severe aortic stenosis, the fixed left ventricular outflow obstruction requires maintaining normal sinus rhythm (atrial kick contributes up to 30% of LV filling), adequate preload, a normal heart rate (avoiding tachycardia which shortens diastolic filling and coronary perfusion time), and maintaining systemic vascular resistance (SVR) with alpha-1 agonists (e.g., phenylephrine or norepinephrine) to ensure adequate coronary perfusion pressure.

Question 33Hemodynamic monitoring, shock and circulation

Which of the following equations accurately describes the Hagen-Poiseuille law governing laminar fluid or gas flow through a cylindrical conduit (such as an endotracheal tube or vascular catheter)?

  1. Flow = (Pressure Gradient × Length × π) / (8 × Viscosity × Radius)
  2. Flow = (Pressure Gradient × Viscosity × Length) / (8 × Radius⁴)
  3. Flow = (8 × Viscosity × Radius⁴) / (Pressure Gradient × π × Length)
  4. Flow = (π × Pressure Gradient × Radius⁴) / (8 × Viscosity × Length) Correct answer.

Explanation

The Hagen-Poiseuille law states that laminar flow (Q) is directly proportional to the pressure gradient (ΔP) and the fourth power of the radius (r⁴), and inversely proportional to fluid viscosity (η) and tube length (L): Q = (π × ΔP × r⁴) / (8 × η × L). Doubling the internal radius increases laminar flow 16-fold, which is the foundational physical principle behind rapid fluid resuscitation with large-bore, short peripheral cannulas.

Question 34Hemodynamic monitoring, shock and circulation

During a sitting-position suboccipital craniotomy for a posterior fossa tumor, the anesthesiologist observes a sudden, precipitously dropped end-tidal CO2 (from 36 to 18 mmHg), acute hypotension, and a 'mill-wheel' murmur on precordial Doppler. What is the immediate diagnosis?

  1. Severe acute malignant hyperthermia crisis
  2. Acute anaphylactic shock to prophylactic cefazolin
  3. Venous air embolism (VAE) Correct answer.
  4. Left-sided tension pneumothorax

Explanation

In sitting neurosurgical procedures, negative gravitational pressure gradients between exposed non-collapsible dural venous sinuses and the right atrium create a high risk for venous air embolism (VAE). Entrained air enters the pulmonary circulation, increasing dead-space ventilation, causing an acute drop in end-tidal CO2 (ETCO2), sudden hypotension, hypoxia, and a classic mill-wheel murmur on precordial Doppler.

Question 35Hemodynamic monitoring, shock and circulation

A 71-year-old patient is undergoing open repair of an infrarenal abdominal aortic aneurysm (AAA). What hemodynamic and physiological response is classically observed immediately following cross-clamping of the infrarenal aorta?

  1. Severe decrease in left ventricular afterload with profound systemic hypotension
  2. Significant increase in left ventricular afterload (increased SVR and blood pressure) and potential myocardial ischemia Correct answer.
  3. Sudden decrease in central venous pressure and pulmonary capillary wedge pressure
  4. Profound respiratory alkalosis due to immediate hyperfusion of lower extremities

Explanation

Aortic cross-clamping abruptly increases systemic vascular resistance (SVR) and left ventricular afterload, resulting in elevated proximal arterial blood pressure, increased LV end-diastolic pressure/volume, and increased myocardial oxygen demand. Vasodilators (such as nitroglycerin, nitroprusside, or deepened volatile anesthesia) are often required to manage this afterload increase.

Question 36Hemodynamic monitoring, shock and circulation

During cardiopulmonary bypass (CPB) separation following coronary artery bypass graft surgery, the patient is successfully weaned off bypass. Transesophageal echocardiography (TEE) shows right ventricular dilation, severe RV hypokinesia, and a leftward shift of the interatrial septum. The central venous pressure is 18 mmHg and MAP is 55 mmHg. Which inotropic and pulmonary vasodilating agent is most appropriate?

  1. High-dose pure alpha-1 agonist phenylephrine infusion
  2. High-dose beta-blocker esmolol infusion
  3. Inhaled milrinone or inhaled prostacyclin (epoprostenol) combined with systemic inotrope/vasopressor (norepinephrine/milrinone) Correct answer.
  4. Intravenous diltiazem bolus to slow AV nodal conduction

Explanation

Acute right ventricular failure post-CPB requires lowering RV afterload (pulmonary vascular resistance) while augmenting RV contractility and maintaining coronary perfusion pressure. Inhaled pulmonary vasodilators (inhaled milrinone, prostacyclin, or nitric oxide) selectively reduce PVR without causing systemic hypotension. Concomitant systemic inotropic/vasopressor support (milrinone, dobutamine, or epinephrine with norepinephrine) helps maintain MAP and right coronary artery perfusion.

Question 37Hemodynamic monitoring, shock and circulation

A 4-month-old infant with a known unrepaired Tetralogy of Fallot (TOF) experiences a severe cyanotic 'hypercyanotic spell' ('tet spell') during induction of anesthesia. What is the underlying pathophysiology of a tet spell, and what is the primary pharmacological intervention?

  1. Acute left ventricular failure; treated with high-dose intravenous milrinone infusion
  2. Massive pulmonary embolism; treated with immediate recombinant tissue plasminogen activator (tPA)
  3. Spasm of the aortic valve leaflets; treated with inhaled nitric oxide
  4. Infundibular subpulmonic muscular spasm with increased right-to-left shunt across the VSD; treated with 100% O2, knee-chest position, volume bolus, morphine, and phenylephrine to increase SVR Correct answer.

Explanation

A 'tet spell' in Tetralogy of Fallot is caused by spasm of the subpulmonary infundibulum and/or a drop in systemic vascular resistance (SVR), which dramatically increases the right-to-left shunt of deoxygenated blood across the VSD into the aorta. Management includes: 100% FiO2, knee-chest positioning (which kinks femoral vessels and increases SVR), IV fluid bolus (increases preload), morphine or propofol (sedation and relieves infundibular spasm), and phenylephrine (increases SVR, reversing the shunt). Beta-blockers (esmolol) can also relax infundibular spasm.

Question 38Hemodynamic monitoring, shock and circulation

During major liver resection with massive blood loss, point-of-care rotational thromboelastometry (ROTEM) is performed. The EXTEM test shows a normal Clotting Time (CT 65 s), but the Maximum Clot Firmness (MCF) is severely reduced at 28 mm (reference 50–72 mm). The FIBTEM MCF is 4 mm (reference 9–25 mm). What is the targeted first-line therapy indicated by this ROTEM profile?

  1. Fibrinogen concentrate (or cryoprecipitate) administration to restore fibrin polymerization Correct answer.
  2. Fresh frozen plasma 4 units to treat factor VII deficiency
  3. Platelet concentrate transfusion as sole therapy
  4. High-dose recombinant activated factor VII (rFVIIa)

Explanation

In ROTEM analysis, a markedly reduced FIBTEM MCF (<8–9 mm) specifically indicates severe hypofibrinogenemia (or impaired fibrin polymerization), because platelets are inhibited by cytochalasin D in the FIBTEM assay. The first-line targeted therapy is fibrinogen concentrate (typically 25–50 mg/kg or 2–4 g IV) to restore clot firmness, which also improves EXTEM MCF.

Question 39Hemodynamic monitoring, shock and circulation

What is the primary physiological basis of dynamic indices of fluid responsiveness (such as Stroke Volume Variation [SVV] and Pulse Pressure Variation [PPV]) during mechanical ventilation in sinus rhythm?

  1. Spontaneous variation in autonomic tone mediated by carotid sinus baroreceptors
  2. Heart-lung interactions during positive-pressure inspiration causing cyclical variations in right and left ventricular preload and stroke volume Correct answer.
  3. Fluctuations in plasma sodium concentration during balanced crystalloid infusion
  4. Direct compression of the aorta by the descending diaphragm during expiration

Explanation

Dynamic preload indices (SVV >12–13% and PPV >13%) rely on cyclic cardiopulmonary interactions during controlled mechanical ventilation (without spontaneous breathing efforts, with tidal volume ≥8 mL/kg PBW, and in normal sinus rhythm). Positive-pressure inspiration increases intrathoracic pressure, transiently decreasing right ventricular venous return (preload) and increasing LV preload, followed 2–3 beats later by decreased LV stroke volume during expiration. A high SVV/PPV indicates that both ventricles are operating on the ascending, preload-dependent limb of the Frank-Starling curve.

Question 40Hemodynamic monitoring, shock and circulation

A massive transfusion protocol is activated for a polytrauma patient in hemorrhagic shock. What is the fundamental rationale for administering balanced 1:1:1 ratios of Packed Red Blood Cells (PRBC), Fresh Frozen Plasma (FFP), and Platelets, alongside early Tranexamic Acid (TXA)?

  1. To prevent trauma-induced coagulopathy (TIC), avoid dilutional thrombocytopenia and factor depletion, and prevent hyperfibrinolysis Correct answer.
  2. To rapidly induce hypercoagulability and complete thrombosis of all injured vessels
  3. To alkalize arterial blood pH above 7.60 to enhance oxygen delivery
  4. To replace albumin losses and avoid the use of balanced crystalloids entirely

Explanation

Trauma-induced coagulopathy (TIC) is driven by tissue injury, shock, hypoperfusion, hypothermia, acidosis, and early hyperfibrinolysis. High-ratio balanced blood component therapy (1:1:1 PRBC:FFP:Platelets) combined with early tranexamic acid (within 3 hours of injury) prevents dilutional coagulopathy and improves survival by maintaining clot firmness and stopping microvascular bleeding.

Question 41Hemodynamic monitoring, shock and circulation

A 60-year-old patient undergoing complex abdominal aortic surgery receives 6 units of PRBCs and 4 units of FFP. The ionized calcium level on blood gas analysis drops to 0.78 mmol/L (normal 1.15–1.30 mmol/L). What is the mechanism of acute hypocalcemia during rapid blood transfusion?

  1. Citrate preservative in transfused blood products binds and chelates ionized calcium, especially when hepatic citrate metabolism is overwhelmed or impaired by hypothermia and shock Correct answer.
  2. Direct degradation of parathyroid hormone by transfused leukocyte proteases
  3. Renal loss of calcium stimulated by high concentrations of potassium in stored PRBCs
  4. Precipitation of calcium with free hemoglobin released from microhemolyzed erythrocytes

Explanation

Stored blood components contain sodium citrate as an anticoagulant preservative. During rapid or massive transfusion, exogenous citrate chelates circulating divalent cations (primarily ionized calcium and magnesium). In the presence of hypothermia, liver dysfunction, or hypoperfusion, hepatic metabolism of citrate to bicarbonate is delayed, causing severe acute hypocalcemia, which impairs myocardial contractility and coagulation factor cascades.

Question 42Hemodynamic monitoring, shock and circulation

A 70-year-old patient with an acute ST-elevation myocardial infarction undergoes emergency percutaneous coronary intervention (PCI) and develops sudden pulseless electrical activity (PEA) arrest. Bedside echocardiography demonstrates a massive pericardial effusion with right ventricular diastolic collapse. What is the reversible cause of arrest ('4 Hs and 4 Ts') and the immediate life-saving intervention?

  1. Tension pneumothorax; immediate bilateral needle decompression
  2. Thrombosis (massive pulmonary embolism); immediate catheter-directed embolectomy
  3. Toxins; immediate high-dose naloxone infusion
  4. Cardiac tamponade; immediate subxiphoid or ultrasound-guided pericardiocentesis Correct answer.

Explanation

Cardiac tamponade is one of the reversible '4 Ts' of PEA cardiac arrest (Tamponade, Tension pneumothorax, Thrombosis coronary/pulmonary, Toxins). Rapid accumulation of fluid in the non-compliant pericardial space impairs diastolic ventricular filling, leading to electromechanical dissociation (PEA). Immediate emergency pericardiocentesis is life-saving and restores cardiac output.

Question 43Hemodynamic monitoring, shock and circulation

What are the three components comprising the 'Lethal Triad' in severely injured trauma patients that dramatically increases mortality and dictates damage control resuscitation principles?

  1. Hypertension, bradycardia, and irregular respirations
  2. Hyperthermia, alkalosis, and thrombocytosis
  3. Hypothermia, acidosis, and coagulopathy Correct answer.
  4. Hypoglycemia, hypokalemia, and hypocalcemia

Explanation

The lethal triad of trauma comprises hypothermia (<35°C), metabolic acidosis (pH <7.20), and trauma-induced coagulopathy. Each component exacerbates the others: hypothermia impairs clotting enzyme kinetics and platelet activation; acidosis directly inhibits coagulation factor complex formation; and ongoing coagulopathic bleeding causes worsening shock, deeper acidosis, and hypothermia.

Question 44Hemodynamic monitoring, shock and circulation

A 28-year-old trauma victim with an unstable pelvic fracture and multiple intra-abdominal lacerations arrives in the trauma bay with active non-compressible torso hemorrhage. What is the fundamental concept of 'Permissive Hypotension' (Damage Control Resuscitation) prior to surgical hemostasis?

  1. Infusing large volumes of cold 0.9% saline to maintain a systolic blood pressure >160 mmHg
  2. Deliberately reducing heart rate to <40 bpm using intravenous esmolol
  3. Inducing severe hyperventilation to reduce intracranial pressure
  4. Restricting aggressive fluid administration and accepting a subnormal blood pressure (target SBP 80–90 mmHg or MAP 50–60 mmHg) in the absence of severe traumatic brain injury until surgical control of bleeding is achieved Correct answer.

Explanation

Permissive hypotension (restricted volume resuscitation) aims to maintain vital organ perfusion (target SBP 80–90 mmHg or MAP 50–60 mmHg) while avoiding dislodgement of newly formed clots ('popping the clot'), dilution of coagulation factors, and exacerbation of hypothermia until surgical or endovascular hemostasis is achieved. Note: Permissive hypotension is contraindicated in severe traumatic brain injury (TBI), where target SBP must be ≥100–110 mmHg to maintain cerebral perfusion.

Question 45Perioperative assessment, regional anatomy and pain

A 31-year-old woman at 38 weeks of gestation undergoes spinal anesthesia for elective cesarean delivery with 10 mg of hyperbaric bupivacaine and 15 mcg fentanyl. Two minutes after injection, her blood pressure drops from 120/75 mmHg to 82/40 mmHg, and she complains of nausea. What is the first-line vasopressor and mechanism of choice to prevent and treat maternal spinal hypotension while optimizing fetal acid-base status?

  1. Intravenous ephedrine boluses, because beta-1 stimulation prevents fetal bradycardia
  2. Intravenous dopamine infusion, because it selectively enhances renal perfusion
  3. Intravenous norepinephrine boluses at 1 mg to induce potent systemic vasoconstriction
  4. Intravenous phenylephrine infusion or titrated boluses (pure alpha-1 adrenoceptor agonist), because it prevents maternal arterial hypotension without causing fetal acidosis Correct answer.

Explanation

Current international consensus guidelines (including ESAIC/OAA/SOAP) recommend phenylephrine (a pure alpha-1 adrenoceptor agonist) as the first-line vasopressor for post-spinal hypotension in cesarean delivery. Phenylephrine effectively restores systemic vascular resistance without crossing the placenta in significant amounts, resulting in higher fetal umbilical artery pH and base excess compared to ephedrine, which crosses the placenta and stimulates fetal metabolism.

Question 46Perioperative assessment, regional anatomy and pain

According to the updated European Society of Anaesthesiology and Intensive Care (ESAIC) pediatric fasting guidelines, what is the recommended minimum fasting time for clear fluids in healthy children prior to elective anesthesia?

  1. 1 hour Correct answer.
  2. 2 hours
  3. 4 hours
  4. 6 hours

Explanation

Updated ESAIC (and Swiss SSAPM) pediatric fasting guidelines recommend a 1-hour fasting time for clear fluids (water, pulp-free juice, clear tea) prior to elective procedures in healthy children. Breast milk requires 3–4 hours, infant formula requires 4 hours, and solids/non-human milk require 6 hours.

Question 47Perioperative assessment, regional anatomy and pain

A 16-year-old patient undergoing posterior spinal fusion for adolescent idiopathic scoliosis is monitored with motor evoked potentials (TcMEPs) and somatosensory evoked potentials (SSEPs). Which anesthetic technique is standard of care to minimize interference with neurophysiological signals?

  1. Deep volatile anesthesia with 1.5 MAC isoflurane and high-dose continuous cisatracurium infusion
  2. High-dose ketamine monotherapy combined with depolarizing neuromuscular blockade
  3. Continuous regional subarachnoid bupivacaine infusion through a lumbar drain
  4. Total Intravenous Anesthesia (TIVA) with propofol and remifentanil, avoiding volatile anesthetics and omitting continuous neuromuscular blockade Correct answer.

Explanation

Volatile inhalational agents (and nitrous oxide) produce dose-dependent suppression of synaptic transmission in the cerebral cortex and anterior horn motor neurons, severely depressing motor evoked potentials (TcMEPs). Neuromuscular blocking agents eliminate muscle compound action potentials. The standard of care for intraoperative neuromonitoring (IONM) is Total Intravenous Anesthesia (TIVA) with propofol and remifentanil with complete avoidance or precise partial titration of muscle relaxants.

Question 48Perioperative assessment, regional anatomy and pain

A 54-year-old patient receives an ultrasound-guided interscalene brachial plexus block with 15 mL of 0.5% ropivacaine for arthroscopic rotator cuff repair. Postoperatively in the recovery room, the patient exhibits ipsilateral ptosis, miosis, and enophthalmos. What is the anatomical structure blocked to produce this syndrome, and what other nearly universal (>99%) side effect accompanies interscalene blocks?

  1. Stellate ganglion block causing Horner syndrome; accompanied by ipsilateral recurrent laryngeal nerve palsy
  2. Sphenopalatine ganglion block; accompanied by facial nerve palsy
  3. Trigeminal ganglion block; accompanied by glossopharyngeal nerve block
  4. Cervical sympathetic chain (stellate ganglion) block causing Horner syndrome; accompanied by ipsilateral phrenic nerve block (hemidiaphragmatic paresis) Correct answer.

Explanation

Interscalene brachial plexus blocks consistently result in local anesthetic spread along the prevertebral fascia, causing: 1) ipsilateral phrenic nerve palsy (hemidiaphragmatic paresis) in virtually 100% of standard-volume blocks (making it contraindicated in severe baseline contralateral pulmonary disease), and 2) blockade of the cervical sympathetic chain (stellate ganglion), producing ipsilateral Horner syndrome (ptosis, miosis, anhydrosis, and enophthalmos).

Question 49Perioperative assessment, regional anatomy and pain

An ultrasound-guided supraclavicular brachial plexus block is performed for distal radius fracture fixation. What is the classic sonographic appearance of the brachial plexus at the supraclavicular level?

  1. A cluster of hypoechoic round structures ('honeycomb' or 'cluster of grapes') located lateral and superficial to the pulsating subclavian artery above the first rib and pleura Correct answer.
  2. A single hyperechoic triangular structure located medial to the internal jugular vein
  3. Three separate hyperechoic cords surrounding the axillary artery deep to the pectoralis minor muscle
  4. Hypoechoic roots exiting between the anterior and middle scalene muscles in a vertical traffic-light stack

Explanation

At the supraclavicular level, the brachial plexus (trunks and divisions) appears sonographically as a compact cluster of hypoechoic nodules ('cluster of grapes' or 'honeycomb' sign) located immediately posterior and lateral to the round, anechoic subclavian artery, sitting directly on the hyperechoic first rib. The hyperechoic pleural line lies medial and deep to the rib.

Question 50Perioperative assessment, regional anatomy and pain

A 68-year-old woman undergoing total knee arthroplasty receives an adductor canal block for postoperative analgesia. Which nerve is the primary sensory target of the adductor canal block, and what major clinical advantage does it offer over a traditional femoral nerve block?

  1. Sciatic nerve; provides complete motor paralysis of all calf muscles
  2. Saphenous nerve (and nerve to vastus medialis); provides effective anterior knee analgesia with preservation of quadriceps motor strength for early ambulation Correct answer.
  3. Lateral femoral cutaneous nerve; provides dense motor block of the rectus femoris
  4. Obturator nerve; eliminates all posterior capsule knee pain while sparing the saphenous nerve

Explanation

The saphenous distribution is a principal sensory target in the relevant adductor-canal approach. Compared with a traditional femoral block, it is used for relative motor sparing while supporting knee analgesia. Technique, spread and individual anatomy can still affect motor function, so normal strength and safe ambulation are not guaranteed.