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Question 1Basic Sciences Foundations of Anesthesia Practice

Which muscle is the principal generator of inspiratory airflow during quiet breathing?

  1. The rectus abdominis muscles
  2. The diaphragm Correct answer.
  3. The external intercostal muscles
  4. The sternocleidomastoid muscles

Explanation

The diaphragm is the principal inspiratory muscle; its contraction lowers intrathoracic pressure and draws air into the lungs. External intercostals assist inspiration, while sternocleidomastoid and abdominal muscles are accessory or expiratory muscles.

Question 2Basic Sciences Foundations of Anesthesia Practice

In a healthy resting adult, which value best approximates cardiac output?

  1. 12 L/min
  2. 8 L/min
  3. 2 L/min
  4. 5 L/min Correct answer.

Explanation

Cardiac output at rest is about 5 L/min in a healthy adult, typically 4–6 L/min depending on body size and metabolic demand. Values near 12 L/min are more typical of exercise or a hyperdynamic state.

Question 3Basic Sciences Foundations of Anesthesia Practice

After an intravenous bolus, what fraction of the administered dose enters the systemic circulation unchanged?

  1. 50%
  2. 25%
  3. 100% Correct answer.
  4. It depends on hepatic blood flow

Explanation

Bioavailability is the fraction of an administered dose that reaches systemic circulation unchanged; after an intravenous bolus this fraction is defined as 100%. Oral bioavailability is lower when first-pass hepatic metabolism or incomplete absorption occurs.

Question 4Basic Sciences Foundations of Anesthesia Practice

Boyle's law describes the relationship between which pair of variables for a fixed mass of gas at constant temperature?

  1. Moles and volume
  2. Pressure and temperature
  3. Volume and temperature
  4. Pressure and volume Correct answer.

Explanation

Boyle's law states that at constant temperature, pressure and volume of a fixed mass of gas are inversely proportional. Volume-temperature is Charles's law, and pressure-temperature is Gay-Lussac's law.

Question 5Basic Sciences Foundations of Anesthesia Practice

Which arterial pH range is considered normal for an adult at sea level?

  1. 7.30–7.35
  2. 7.35–7.45 Correct answer.
  3. 7.20–7.30
  4. 7.45–7.55

Explanation

Normal arterial pH is 7.35–7.45; values below 7.35 indicate acidemia and values above 7.45 indicate alkalemia. The other ranges represent abnormal acid-base states.

Question 6Basic Sciences Foundations of Anesthesia Practice

The diaphragm receives its motor innervation from which nerve?

  1. Recurrent laryngeal nerve
  2. Intercostal nerves
  3. Vagus nerve
  4. Phrenic nerve Correct answer.

Explanation

The phrenic nerve (C3–C5) provides motor innervation to the diaphragm. The vagus and recurrent laryngeal nerves supply laryngeal and thoracic visceral structures, and intercostal nerves supply intercostal muscles.

Question 7Basic Sciences Foundations of Anesthesia Practice

Functional residual capacity is the sum of which two lung volumes?

  1. Expiratory reserve volume and residual volume Correct answer.
  2. Tidal volume and residual volume
  3. Inspiratory reserve volume and residual volume
  4. Tidal volume and inspiratory reserve volume

Explanation

Functional residual capacity is the volume remaining in the lungs after a normal expiration and equals expiratory reserve volume plus residual volume. It reflects the balance between outward chest wall recoil and inward lung recoil.

Question 8Basic Sciences Foundations of Anesthesia Practice

First-pass metabolism primarily occurs in which organ after oral drug administration?

  1. Liver Correct answer.
  2. Lungs
  3. Plasma
  4. Kidneys

Explanation

After oral absorption, portal blood carries drug to the liver, where first-pass metabolism can reduce systemic bioavailability. The lungs, kidneys, and plasma may contribute to metabolism but are not the primary site of the first-pass effect.

Question 9Basic Sciences Foundations of Anesthesia Practice

A patient has cardiac output 5 L/min, hemoglobin 15 g/dL, and arterial oxygen saturation 100% with PaO2 100 mm Hg. Using the simplified oxygen delivery equation, which value is closest to oxygen delivery? Assume 1.34 mL O2/g Hb and ignore dissolved O2.

  1. 1000 mL/min Correct answer.
  2. 750 mL/min
  3. 500 mL/min
  4. 1500 mL/min

Explanation

CaO2 ≈ 1.34 × Hb × SaO2 = 1.34 × 15 × 1.00 ≈ 20.1 mL/dL. DO2 = CO × CaO2 × 10 = 5 × 20.1 × 10 ≈ 1005 mL/min, closest to 1000 mL/min.

Question 10Basic Sciences Foundations of Anesthesia Practice

A drug has a volume of distribution of 50 L and a clearance of 5 L/h. What is its elimination half-life?

  1. 7 hours Correct answer.
  2. 35 hours
  3. 10 hours
  4. 3.5 hours

Explanation

Half-life is calculated as 0.693 × Vd / CL. With Vd 50 L and CL 5 L/h, t1/2 = 0.693 × 10 h ≈ 6.9 h, closest to 7 hours.

Question 11Basic Sciences Foundations of Anesthesia Practice

At sea level with FiO2 0.21, barometric pressure 760 mm Hg, PaCO2 40 mm Hg, and respiratory quotient 0.8, what is the approximate alveolar oxygen partial pressure?

  1. 60 mm Hg
  2. 150 mm Hg
  3. 80 mm Hg
  4. 100 mm Hg Correct answer.

Explanation

PAO2 = FiO2(PB − PH2O) − PaCO2/R. Substituting gives 0.21(760 − 47) − 40/0.8 ≈ 149.7 − 50 ≈ 100 mm Hg.

Question 12Basic Sciences Foundations of Anesthesia Practice

Which condition most directly increases physiologic dead space by adding alveolar dead space?

  1. Diffuse alveolar hemorrhage
  2. Pulmonary embolism Correct answer.
  3. Metabolic alkalosis
  4. Severe anemia

Explanation

Pulmonary embolism obstructs pulmonary blood flow, creating alveoli that are ventilated but not perfused; this is alveolar dead space. Hemorrhage affects diffusion, anemia affects oxygen content, and alkalosis affects ventilation but not dead space directly.

Question 13Basic Sciences Foundations of Anesthesia Practice

Within the physiologic range, an increase in left ventricular end-diastolic volume increases stroke volume through which mechanism?

  1. The Anrep afterload response
  2. The Bayliss myogenic response
  3. The Bowditch force-frequency staircase
  4. The Frank-Starling relationship Correct answer.

Explanation

The Frank-Starling mechanism states that increasing end-diastolic volume stretches myocardial fibers and increases force of contraction within physiologic limits. The Bowditch staircase and Anrep effect describe force-frequency and afterload-related changes, respectively.

Question 14Basic Sciences Foundations of Anesthesia Practice

MAC is defined as the alveolar concentration of an inhaled anesthetic at which:

  1. 50% of patients do not move in response to a standard surgical stimulus Correct answer.
  2. Consciousness is lost in all patients
  3. Cardiac output decreases by 50%
  4. 95% of patients do not move in response to a standardized surgical stimulus

Explanation

MAC is the minimum alveolar concentration at which 50% of patients do not move in response to a standard surgical stimulus. It is a measure of potency, not of cardiac depression or guaranteed amnesia.

Question 15Basic Sciences Foundations of Anesthesia Practice

Two opioids produce the same maximal analgesia, but drug A requires a lower dose than drug B to produce 50% of that maximal effect. What does this indicate?

  1. Drug A has greater potency Correct answer.
  2. Drug A has a lower therapeutic index
  3. Drug A is a competitive antagonist
  4. Drug A has greater efficacy

Explanation

Potency refers to the dose required to produce a given effect and is reflected by the ED50; a lower ED50 means greater potency. Efficacy refers to maximal effect, which is equal here.

Question 16Basic Sciences Foundations of Anesthesia Practice

Local anesthetics block nerve conduction primarily by inhibiting which target?

  1. Voltage-gated sodium channels Correct answer.
  2. Voltage-gated calcium channels
  3. Voltage-gated potassium channels
  4. Ligand-gated GABA receptors

Explanation

Local anesthetics bind voltage-gated sodium channels and prevent sodium influx, blocking action potential propagation. Potassium, calcium, and GABA targets are not their primary mechanism.

Question 17Basic Sciences Foundations of Anesthesia Practice

Succinylcholine produces muscle relaxation through which mechanism?

  1. Inhibition of acetylcholinesterase
  2. Blockade of presynaptic calcium channels
  3. Persistent depolarization of the motor end plate Correct answer.
  4. Competitive antagonism at nicotinic acetylcholine receptors

Explanation

Succinylcholine is a depolarizing neuromuscular blocker that binds nicotinic receptors and causes persistent depolarization of the motor end plate. Competitive blockers such as rocuronium antagonize acetylcholine at the same receptor.

Question 18Basic Sciences Foundations of Anesthesia Practice

Which change would most likely decrease glomerular filtration rate?

  1. Constriction of the afferent arteriole Correct answer.
  2. Increased glomerular capillary surface area
  3. Dilation of the afferent arteriole
  4. Dilation of the efferent arteriole

Explanation

Afferent arteriolar constriction reduces renal blood flow and glomerular capillary pressure, lowering GFR. Efferent constriction tends to preserve or increase GFR, and afferent dilation increases it.

Question 19Basic Sciences Foundations of Anesthesia Practice

In a patient with normal intracranial pressure, which change most strongly increases cerebral blood flow?

  1. Decreased PaCO2 from 40 to 30 mm Hg
  2. Decreased mean arterial pressure from 90 to 70 mm Hg
  3. Increased PaO2 from 100 to 200 mm Hg
  4. Increased PaCO2 from 40 to 50 mm Hg Correct answer.

Explanation

Cerebral blood flow is highly sensitive to PaCO2; hypercapnia causes cerebral vasodilation and increased flow. Changes in PaO2 within the normal-to-high range have little effect, and moderate hypotension is usually autoregulated.

Question 20Basic Sciences Foundations of Anesthesia Practice

In an average adult, total body water approximates what percentage of body weight?

  1. 40%
  2. 50%
  3. 20%
  4. 60% Correct answer.

Explanation

Total body water is approximately 60% of body weight in a typical adult, distributed mainly intracellularly and extracellularly. The other percentages substantially underestimate this compartment.

Question 21Basic Sciences Foundations of Anesthesia Practice

According to Poiseuille's law for laminar flow, which change has the greatest effect on resistance through a tube?

  1. Halving the pressure gradient
  2. Doubling the fluid viscosity
  3. Doubling the tube length
  4. Halving the tube radius Correct answer.

Explanation

Poiseuille resistance is proportional to length and viscosity and inversely proportional to the fourth power of radius. Halving the radius increases resistance 16-fold, far more than doubling length or viscosity.

Question 22Basic Sciences Foundations of Anesthesia Practice

The concentration of an inhaled anesthetic delivered by a variable-bypass vaporizer depends primarily on which property?

  1. The patient's functional residual capacity and compliance
  2. The fresh gas flow rate delivered to the common gas outlet
  3. The agent's blood-gas solubility coefficient at body temperature
  4. Saturated vapor pressure at the vaporizer temperature Correct answer.

Explanation

In a variable-bypass vaporizer, saturated vapor is diluted by bypass gas; the saturated vapor pressure at the agent's temperature sets the maximum vapor concentration that can be delivered. Blood solubility and patient FRC affect uptake and effect, not the delivered concentration setting.

Question 23Basic Sciences Foundations of Anesthesia Practice

Pulse oximetry estimates arterial oxygen saturation by comparing absorbance of red and infrared light. Which statement best explains its reliance on a pulsatile signal?

  1. It isolates the arterial pulse signal Correct answer.
  2. It corrects for carboxyhemoglobin
  3. It estimates cardiac output
  4. It measures dissolved oxygen tension

Explanation

Pulse oximetry uses the pulsatile component of light absorbance to distinguish arterial blood from nonpulsatile venous and tissue components. It does not directly measure dissolved oxygen, carboxyhemoglobin, or cardiac output.

Question 24Basic Sciences Foundations of Anesthesia Practice

A patient has pH 7.25, PaCO2 30 mm Hg, and HCO3 13 mEq/L. What is the primary acid-base disorder?

  1. Respiratory alkalosis
  2. Metabolic alkalosis
  3. Metabolic acidosis Correct answer.
  4. Respiratory acidosis

Explanation

A pH of 7.25 indicates acidemia. The low bicarbonate of 13 mEq/L indicates a primary metabolic acidosis, and the PaCO2 of 30 mm Hg represents respiratory compensation.

Question 25Basic Sciences Foundations of Anesthesia Practice

Context-sensitive half-time is best described as the time required for plasma concentration to decrease by 50% after:

  1. Oral administration of a sustained-release tablet
  2. Reaching steady-state plasma concentration
  3. A single intravenous bolus Correct answer.
  4. Cessation of a continuous infusion of a specified duration

Explanation

Context-sensitive half-time is the time for plasma concentration to fall by half after ending an infusion, and it increases with infusion duration for lipophilic drugs. After a single bolus, the relevant measure is simply elimination half-life.

Question 26Basic Sciences Foundations of Anesthesia Practice

Which buffer system provides the largest contribution to extracellular pH buffering in the body?

  1. Hemoglobin buffer system
  2. Bicarbonate buffer system Correct answer.
  3. Plasma protein buffer system
  4. Phosphate buffer system

Explanation

Bicarbonate, operating through the carbonic acid-bicarbonate equilibrium, is the principal extracellular buffer and is regulated by the lungs and kidneys. Phosphate is quantitatively more important in urine, while hemoglobin and other proteins buffer mainly within cells or at a smaller extracellular capacity.

Question 27Basic Sciences Foundations of Anesthesia Practice

The first heart sound is produced by which event?

  1. Opening of the atrioventricular valves
  2. Opening of the semilunar valves
  3. Closure of the atrioventricular valves Correct answer.
  4. Closure of the aortic and pulmonic valves

Explanation

The first heart sound arises from closure of the mitral and tricuspid (atrioventricular) valves at the onset of ventricular systole. Semilunar valve closure produces the second heart sound, and valve opening is generally silent.

Question 28Basic Sciences Foundations of Anesthesia Practice

An increase in 2,3-diphosphoglycerate has which effect on hemoglobin?

  1. It decreases hemoglobin carbon dioxide affinity.
  2. It increases hemoglobin oxygen affinity.
  3. It increases hemoglobin carbon dioxide affinity.
  4. It decreases hemoglobin oxygen affinity. Correct answer.

Explanation

Increasing 2,3-DPG stabilizes deoxyhemoglobin, shifting the oxyhemoglobin dissociation curve to the right. This reduces oxygen affinity and favors oxygen unloading at the tissues. Carbon dioxide affinity is described by the Haldane effect and is not the primary action of 2,3-DPG.

Question 29Basic Sciences Foundations of Anesthesia Practice

Mean arterial pressure is most commonly estimated using which formula?

  1. Diastolic pressure plus two-thirds of the pulse pressure
  2. Diastolic pressure plus one-third of the pulse pressure Correct answer.
  3. Systolic pressure plus one-third of the pulse pressure
  4. Systolic pressure minus diastolic pressure

Explanation

Mean arterial pressure is approximated as diastolic pressure plus one-third of the pulse pressure, where pulse pressure is systolic minus diastolic. This weighting reflects the longer duration of diastole relative to systole in the cardiac cycle.

Question 30Basic Sciences Foundations of Anesthesia Practice

An inhaled anesthetic has a low blood:gas partition coefficient. Compared with an agent that has a high blood:gas partition coefficient, this agent will produce which effect?

  1. A higher MAC value
  2. A slower rise in alveolar partial pressure
  3. A faster rise in alveolar partial pressure Correct answer.
  4. A greater degree of hepatic metabolism

Explanation

A low blood:gas partition coefficient means the agent is relatively insoluble in blood, so less drug is taken up by blood as it enters the lung. Alveolar partial pressure therefore rises quickly toward the inspired value, speeding induction. MAC and hepatic metabolism are not determined by the blood:gas partition coefficient.

Question 31Basic Sciences Foundations of Anesthesia Practice

Neostigmine reverses nondepolarizing neuromuscular blockade by which mechanism?

  1. Increasing acetylcholine release from the presynaptic nerve terminal
  2. Blocking nicotinic acetylcholine receptors at the motor end plate
  3. Inhibiting acetylcholinesterase Correct answer.
  4. Stimulating presynaptic alpha-2 adrenergic receptors

Explanation

Neostigmine inhibits acetylcholinesterase, reducing acetylcholine breakdown at the neuromuscular junction. The increased acetylcholine competes with the nondepolarizing blocker and restores neuromuscular transmission. It does not act by blocking receptors or altering presynaptic alpha-2 receptors.

Question 32Basic Sciences Foundations of Anesthesia Practice

A drug follows first-order elimination. If the plasma concentration is doubled, what happens to the rate of elimination?

  1. It decreases by half.
  2. It increases fourfold.
  3. It remains unchanged.
  4. It doubles. Correct answer.

Explanation

In first-order elimination, the rate of drug removal is directly proportional to plasma concentration. Doubling the concentration therefore doubles the amount eliminated per unit time, while the half-life remains constant.

Question 33Basic Sciences Foundations of Anesthesia Practice

Rifampin is administered chronically with warfarin. Which effect is most likely?

  1. Increased warfarin effect due to protein-binding displacement
  2. Decreased warfarin effect due to enzyme induction Correct answer.
  3. Increased warfarin effect due to enzyme inhibition
  4. No change because warfarin is renally cleared

Explanation

Rifampin is a potent inducer of hepatic cytochrome P450 enzymes, which increases warfarin metabolism. The result is a lower warfarin concentration and reduced anticoagulant effect, so INR should be monitored. Warfarin is not principally renally cleared, and rifampin does not act mainly by protein-binding displacement.

Question 34Basic Sciences Foundations of Anesthesia Practice

Which change most directly increases net fluid filtration across a systemic capillary?

  1. Decreased capillary permeability
  2. Increased capillary hydrostatic pressure Correct answer.
  3. Increased plasma oncotic pressure
  4. Increased interstitial hydrostatic pressure

Explanation

Net capillary filtration is governed by Starling forces: capillary hydrostatic pressure favors filtration, while plasma oncotic pressure and interstitial hydrostatic pressure oppose it. Increasing capillary hydrostatic pressure therefore directly increases net filtration. Decreased permeability would reduce filtration.

Question 35Basic Sciences Foundations of Anesthesia Practice

A patient has sodium 140 mEq/L, glucose 180 mg/dL, and blood urea nitrogen 28 mg/dL. What is the calculated plasma osmolality?

  1. 280 mOsm/kg
  2. 290 mOsm/kg
  3. 310 mOsm/kg
  4. 300 mOsm/kg Correct answer.

Explanation

Calculated plasma osmolality is 2 x sodium + glucose/18 + BUN/2.8. For these values, 2 x 140 = 280, glucose contributes 10, and BUN contributes 10, for a total of 300 mOsm/kg. The other values arise from arithmetic errors or omission of one term.

Question 36Basic Sciences Foundations of Anesthesia Practice

A local anesthetic is injected into inflamed, acidic tissue. What is the most likely effect on the block?

  1. Reduced blockade because less drug is uncharged Correct answer.
  2. Enhanced blockade because more drug is ionized
  3. No change because pH does not affect local anesthetics
  4. Enhanced blockade because more drug is uncharged

Explanation

Local anesthetics cross the nerve membrane in their uncharged base form. In acidic inflamed tissue, a larger fraction remains ionized and less uncharged drug is available to penetrate the membrane, weakening the block. Increasing ionized drug without membrane penetration does not enhance blockade.

Question 37Basic Sciences Foundations of Anesthesia Practice

Volatile anesthetics produce hypnosis primarily by enhancing which receptor-mediated current?

  1. Chloride current through GABA-A receptors Correct answer.
  2. Calcium current through L-type channels
  3. Sodium current through nicotinic receptors
  4. Potassium current through ATP-sensitive channels

Explanation

Volatile anesthetics potentiate inhibitory neurotransmission by enhancing chloride current through GABA-A receptors. This increases neuronal hyperpolarization and contributes to hypnosis and amnesia. Nicotinic sodium currents, L-type calcium currents, and ATP-sensitive potassium currents are not the principal targets for this effect.

Question 38Basic Sciences Foundations of Anesthesia Practice

A patient has sodium 140 mEq/L, chloride 105 mEq/L, bicarbonate 15 mEq/L, and albumin 2.0 g/dL. Which statement best describes the acid-base status?

  1. High anion gap metabolic acidosis with a normal corrected gap
  2. High anion gap metabolic acidosis Correct answer.
  3. Normal anion gap metabolic acidosis
  4. Mixed respiratory and metabolic alkalosis

Explanation

The anion gap is sodium minus chloride minus bicarbonate, or 140 - 105 - 15 = 20 mEq/L, which is elevated. Hypoalbuminemia lowers the measured gap, so the albumin-corrected gap is even higher at about 25 mEq/L. The correct interpretation is therefore a high anion gap metabolic acidosis, not a normal gap or a mixed alkalosis.

Question 39Basic Sciences Foundations of Anesthesia Practice

A competitive antagonist is added to a tissue bath containing a full agonist. Which change in the agonist dose-response curve is expected?

  1. A leftward shift with reduced maximal response
  2. A leftward shift with unchanged maximal response
  3. A rightward shift with unchanged maximal response Correct answer.
  4. A rightward shift with reduced maximal response

Explanation

A competitive antagonist competes reversibly with the agonist at the same receptor. It shifts the agonist dose-response curve to the right, requiring more agonist to achieve the same effect, but a sufficiently high agonist concentration can overcome it, so maximal response is unchanged. Noncompetitive antagonists reduce maximal response.

Question 40Basic Sciences Foundations of Anesthesia Practice

The Haldane effect contributes to carbon dioxide transport by which mechanism?

  1. Carbon dioxide is converted to carbaminohemoglobin in plasma
  2. Oxygenated hemoglobin binds more carbon dioxide
  3. Deoxygenated hemoglobin binds more carbon dioxide Correct answer.
  4. Carbon dioxide directly binds to plasma proteins

Explanation

The Haldane effect states that deoxygenated hemoglobin has a greater capacity to carry carbon dioxide, largely through carbamino formation on globin. As hemoglobin releases oxygen in tissues, it therefore takes up more CO2, aiding transport to the lungs. Carbaminohemoglobin forms on hemoglobin, not plasma proteins.

Question 41Anesthesia Equipment, Monitoring, and Technology

In the United States, which color identifies a nitrous oxide pipeline under the medical gas color code?

  1. Gray
  2. Green
  3. Blue Correct answer.
  4. Yellow

Explanation

The US convention assigns blue to nitrous oxide, green to oxygen, yellow to medical air, and gray to carbon dioxide. The color is repeated on hoses, connectors, and outlet labels so that a gas supply can be verified visually before connection.

Question 42Anesthesia Equipment, Monitoring, and Technology

Which pin-index positions are correct for an oxygen cylinder?

  1. 3 and 5
  2. 2 and 5 Correct answer.
  3. 1 and 5
  4. 1 and 6

Explanation

The pin index safety system assigns oxygen to positions 2 and 5, medical air to 1 and 5, nitrous oxide to 3 and 5, and carbon dioxide to 1 and 6. Mismatched pins physically prevent an incorrect cylinder from seating on the yoke.

Question 43Anesthesia Equipment, Monitoring, and Technology

Soda lime that uses ethyl violet as its indicator changes from white to which color as it becomes exhausted?

  1. Brown
  2. Pink
  3. Yellow
  4. Violet Correct answer.

Explanation

Ethyl violet is colorless in fresh absorbent and turns violet as the pH falls with accumulated carbon dioxide. Phenolphthalein-based absorbents behave differently, starting pink and fading to white. Indicator color is only a rough guide, because an exhausted canister can partly regenerate after a period of rest.

Question 44Anesthesia Equipment, Monitoring, and Technology

Pulse oximetry estimates arterial oxygen saturation by comparing which of the following?

  1. Electrical impedance across the digit
  2. Partial pressure of dissolved oxygen in plasma
  3. Light absorption at two wavelengths Correct answer.
  4. Doppler shift of reflected ultrasound

Explanation

The probe transmits red and infrared light and applies the Beer-Lambert relationship to the pulsatile (AC) component, which is assumed to arise from arterial blood. The ratio of absorption at the two wavelengths is mapped to a saturation value. The device reports saturation, not dissolved oxygen tension.

Question 45Anesthesia Equipment, Monitoring, and Technology

Which laryngoscope blade is curved, carries a flange on its left side, and is designed to sit in the vallecula?

  1. Wis-Hipple
  2. Macintosh Correct answer.
  3. Miller
  4. Belscope

Explanation

The Macintosh blade is curved and its tip is placed in the vallecula, indirectly lifting the epiglottis; the flange helps displace the tongue and guide the tube. Straight blades such as the Miller are placed under the epiglottis and lift it directly.

Question 46Anesthesia Equipment, Monitoring, and Technology

What is the primary purpose of the anesthesia gas scavenging system?

  1. To warm and humidify the inspired gas
  2. To remove waste anesthetic gas Correct answer.
  3. To absorb carbon dioxide from the circuit
  4. To measure inspired oxygen concentration

Explanation

The scavenging system collects excess gas released at the adjustable pressure-limiting valve and the ventilator relief valve and vents it away from the workspace. It protects operating room personnel from trace agent exposure. It does not participate in humidification, carbon dioxide removal, or gas analysis.

Question 47Anesthesia Equipment, Monitoring, and Technology

A blood pressure cuff bladder should have a width of approximately what percentage of the limb circumference?

  1. 80%
  2. 40% Correct answer.
  3. 60%
  4. 20%

Explanation

The recommended bladder width is about 40% of the limb circumference, with a length of roughly 80%. A cuff that is too narrow overestimates the pressure, while one that is too wide underestimates it.

Question 48Anesthesia Equipment, Monitoring, and Technology

How many liters of oxygen does a full E-cylinder hold at standard conditions?

  1. 660 L Correct answer.
  2. 1590 L
  3. 300 L
  4. 220 L

Explanation

A full E-cylinder holds about 660 L of oxygen at roughly 2200 psig, whereas an H-cylinder holds about 6900 L. Knowing the capacity allows quick estimation of how long a cylinder will last at a given flow.

Question 49Anesthesia Equipment, Monitoring, and Technology

During volume-controlled ventilation with a circle system at 1 L/min fresh gas flow, the inspired carbon dioxide concentration is 8 mmHg and rising while the expiratory plateau is unchanged. What is the most likely cause?

  1. A slow leak around the tracheal tube cuff
  2. Hyperventilation of the patient
  3. Exhausted carbon dioxide absorbent Correct answer.
  4. Malfunction of the oxygen analyzer

Explanation

Carbon dioxide in the inspired gas means gas is being rebreathed without adequate absorption, which occurs with exhaustion of the absorbent or channeling through the canister. A cuff leak lowers end-tidal values rather than raising the inspired baseline. The absorbent should be replaced and the canister inspected.

Question 50Anesthesia Equipment, Monitoring, and Technology

Desflurane is given from a heated, pressurized, electronically controlled vaporizer rather than a variable-bypass vaporizer mainly because desflurane does which of the following?

  1. Has a vapor pressure near atmospheric pressure Correct answer.
  2. Is a strong airway irritant
  3. Has a low minimum alveolar concentration
  4. Has a very low blood-gas solubility

Explanation

Desflurane boils at about 22.8 degrees C and has a vapor pressure near 669 mmHg at room temperature, so a conventional flow-over vaporizer would deliver unstable, unpredictable output. The agent-specific device heats and pressurizes the agent and meters pure vapor into the fresh gas stream.