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Egyptian Board Critical Care study materials
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Egyptian Board Critical Care practice questions

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Question 1Respiratory failure and mechanical ventilation

A 62-year-old man with COPD has an arterial blood gas showing pH 7.28, PaCO2 68 mmHg, PaO2 55 mmHg on room air. What is the most appropriate description of this respiratory failure?

  1. Acute hypoxaemic respiratory failure with normal PaCO2
  2. Type I respiratory failure with respiratory alkalosis
  3. Chronic compensated metabolic acidosis
  4. Acute hypercapnic respiratory failure with hypoxaemia Correct answer.

Explanation

Type II (hypercapnic) respiratory failure is defined by a PaCO2 above 50 mmHg, and the acidotic pH of 7.28 indicates it is acute rather than fully compensated. The low PaO2 confirms concurrent hypoxaemia, which is typical when alveolar hypoventilation is the dominant mechanism.

Question 2Respiratory failure and mechanical ventilation

Which arterial blood gas finding best distinguishes type I from type II respiratory failure?

  1. PaO2 below 80 mmHg with bicarbonate above 30 mmol/L
  2. PaO2 below 60 mmHg with PaCO2 at or below 45 mmHg Correct answer.
  3. PaCO2 above 50 mmHg with normal pH
  4. PaO2 below 60 mmHg with PaCO2 above 50 mmHg

Explanation

Type I failure is hypoxaemic with a normal or low PaCO2, whereas type II failure adds hypercapnia above roughly 50 mmHg. The defining discriminator is therefore the PaCO2 in the presence of hypoxaemia.

Question 3Respiratory failure and mechanical ventilation

A patient with acute respiratory distress syndrome is ventilated with a tidal volume of 6 mL/kg predicted body weight. Which physiological benefit is the main reason for this low tidal volume strategy?

  1. Reduction of alveolar overdistension and ventilator-induced lung injury Correct answer.
  2. Increase in cardiac output through higher intrathoracic pressure
  3. Prevention of auto-triggering during pressure support
  4. Elimination of the need for positive end-expiratory pressure

Explanation

Lung-protective ventilation limits tidal stretch of aerated lung units, reducing volutrauma and barotrauma in the heterogeneous ARDS lung. This strategy lowers mortality compared with traditional higher tidal volumes.

Question 4Respiratory failure and mechanical ventilation

Which parameter is used to set the initial tidal volume during lung-protective ventilation in a patient with ARDS?

  1. Ideal body weight estimated from the body mass index
  2. Predicted body weight calculated from height and sex Correct answer.
  3. Lean body mass measured by bioimpedance
  4. Actual body weight measured on the bed scale

Explanation

Tidal volume in ARDS is targeted at about 6 mL/kg of predicted body weight, which is derived from height and sex. Predicted body weight reflects lung size better than actual weight, which is distorted by oedema or adiposity.

Question 5Respiratory failure and mechanical ventilation

A ventilated patient has a peak airway pressure of 42 cmH2O and a plateau pressure of 34 cmH2O. What is the most likely explanation?

  1. Raised intra-abdominal pressure
  2. Increased airway resistance Correct answer.
  3. Reduced chest wall compliance
  4. Pleural effusion compressing the lung

Explanation

A large gradient between peak and plateau pressure (here 8 cmH2O) reflects resistive pressure loss, indicating increased airway resistance such as bronchospasm or a narrowed endotracheal tube. Plateau pressure alone reflects alveolar and chest wall compliance.

Question 6Respiratory failure and mechanical ventilation

Which finding on the ventilator waveform suggests the presence of auto-PEEP in a patient with severe asthma?

  1. A square inspiratory flow pattern
  2. A plateau pressure equal to the peak pressure
  3. A rising peak pressure with a stable plateau pressure
  4. Expiratory flow that fails to return to zero before the next breath Correct answer.

Explanation

Incomplete exhalation, with expiratory flow not reaching zero before the next inspiration, indicates air trapping and dynamic hyperinflation. This produces intrinsic or auto-PEEP, which can impair venous return and cause hypotension.

Question 7Respiratory failure and mechanical ventilation

A patient with severe ARDS is being considered for prone positioning. Which criterion best reflects the evidence-based indication?

  1. PaO2/FiO2 ratio below 150 mmHg despite optimised ventilation Correct answer.
  2. Presence of unilateral lobar pneumonia
  3. PaO2/FiO2 ratio below 300 mmHg on high-flow nasal oxygen
  4. Need for recruitment manoeuvres during weaning

Explanation

Prone positioning improves survival in moderate-to-severe ARDS, generally defined by a PaO2/FiO2 ratio below 150 mmHg on optimised settings. Sessions are typically prolonged, around 16 hours per day.

Question 8Respiratory failure and mechanical ventilation

Which mode of non-invasive ventilation is preferred for an acute exacerbation of COPD with hypercapnic acidosis?

  1. High-flow nasal cannula alone
  2. Simple face mask with venturi entrainment
  3. Continuous positive airway pressure at 5 cmH2O
  4. Bilevel positive airway pressure via a tight-fitting mask Correct answer.

Explanation

Bilevel positive airway pressure provides inspiratory pressure support that augments alveolar ventilation and reduces PaCO2, and is the established first-line non-invasive support for hypercapnic COPD exacerbation. It also reduces intubation and mortality when applied early.

Question 9Respiratory failure and mechanical ventilation

A patient with Guillain-Barre syndrome is being monitored for respiratory failure. Which bedside measure best predicts the need for mechanical ventilation?

  1. Respiratory rate above 20 breaths per minute
  2. Oxygen saturation below 94 percent on room air
  3. PaCO2 above 38 mmHg
  4. Vital capacity trending downward toward 15 mL/kg Correct answer.

Explanation

In neuromuscular weakness, ventilatory capacity falls before oxygenation deteriorates, so serial vital capacity is the key monitoring tool. A vital capacity approaching 15 mL/kg, or a rapid decline, signals impending failure requiring intubation.

Question 10Respiratory failure and mechanical ventilation

Which of the following is a recognised absolute contraindication to non-invasive ventilation in acute respiratory failure?

  1. Hypercapnic COPD exacerbation
  2. Cardiogenic pulmonary oedema
  3. Immunocompromised status with pneumonia
  4. Facial trauma with an unstable airway Correct answer.

Explanation

Non-invasive ventilation requires a patent, protected airway and a mask that can seal safely; facial trauma with airway instability precludes this and mandates intubation. Many other conditions, including COPD and cardiogenic oedema, are positive indications.

Question 11Respiratory failure and mechanical ventilation

A ventilated patient in the ICU becomes suddenly hypotensive with a peak airway pressure of 45 cmH2O, absent breath sounds on the right, and tracheal deviation to the left. What is the immediate priority?

  1. Obtaining a portable chest radiograph before acting
  2. Needle decompression of the right pleural space Correct answer.
  3. Administering a fluid bolus and reassessing
  4. Increasing PEEP to recruit the right lung

Explanation

The picture is tension pneumothorax, a life-threatening emergency in positive-pressure ventilation, and immediate needle decompression is required before any imaging. Delay for radiography or fluid resuscitation risks cardiac arrest.

Question 12Respiratory failure and mechanical ventilation

Which oxygen delivery device provides the most reliable and highest fraction of inspired oxygen in a spontaneously breathing patient with a poor respiratory effort?

  1. Nasal cannula at 4 L/min
  2. Simple face mask at 6 L/min
  3. Non-rebreather mask with reservoir at 15 L/min Correct answer.
  4. Venturi mask at 28 percent

Explanation

A non-rebreather mask with a reservoir bag delivers the highest reliable FiO2 among standard devices, approaching 0.85 to 0.95 when well seated. Low-flow devices such as nasal cannula or simple masks are limited by variable entrainment of room air.

Question 13Respiratory failure and mechanical ventilation

Which mechanism explains hypoxaemia in a patient with pneumonia and a right-to-left intrapulmonary shunt?

  1. Diffusion of carbon dioxide is impaired across the membrane
  2. Alveolar oxygen tension rises above arterial tension
  3. Mixed venous blood passes through unventilated alveoli without oxygenation Correct answer.
  4. Reduced inspired oxygen concentration reaches the alveoli

Explanation

Shunt occurs when blood perfuses alveoli that are not ventilated, so it returns to the left heart without taking up oxygen. Shunt is poorly responsive to supplemental oxygen because the affected units remain unventilated.

Question 14Respiratory failure and mechanical ventilation

A patient with ARDS is on volume-controlled ventilation with a plateau pressure of 32 cmH2O. Which action is most consistent with lung-protective principles?

  1. Switch to high tidal volumes with permissive hypercapnia
  2. Increase tidal volume to correct hypercapnia
  3. Reduce tidal volume and reassess plateau pressure Correct answer.
  4. Increase PEEP without measuring plateau pressure

Explanation

A plateau pressure above 30 cmH2O suggests excessive alveolar stretch, so reducing tidal volume is the first step to keep plateau pressure at or below 30 cmH2O. Permissive hypercapnia is accepted to protect the lung.

Question 15Respiratory failure and mechanical ventilation

Which statement about the physiological dead space in a patient with pulmonary embolism is most accurate?

  1. Dead space is unaffected because ventilation is preserved
  2. Dead space increases because of reduced tidal volume alone
  3. Dead space decreases because blood is diverted to healthy lung
  4. Dead space increases because ventilated alveoli are not perfused Correct answer.

Explanation

Dead space refers to ventilation of unperfused alveoli, and pulmonary embolism obstructs perfusion, so ventilation is wasted. The resulting increase in dead space fraction raises the work of breathing and contributes to hypercapnia.

Question 16Respiratory failure and mechanical ventilation

A patient with COPD retains carbon dioxide and has an oxygen saturation target. Which target range is recommended for controlled oxygen therapy in this group?

  1. 94 to 98 percent
  2. 88 to 92 percent Correct answer.
  3. 80 to 85 percent
  4. 98 to 100 percent

Explanation

In patients at risk of hypercapnic respiratory failure, oxygen is titrated to a saturation of 88 to 92 percent to avoid worsening hypercapnia. Higher targets risk precipitating or aggravating carbon dioxide retention.

Question 17Respiratory failure and mechanical ventilation

Which ventilator setting change would most directly reduce the risk of ventilator-associated lung injury from cyclic alveolar collapse and reopening?

  1. Increasing tidal volume
  2. Applying adequate positive end-expiratory pressure Correct answer.
  3. Reducing inspiratory time to a minimum
  4. Increasing the respiratory rate

Explanation

Adequate PEEP keeps alveoli open at end-expiration, reducing atelectrauma from repeated recruitment and derecruitment. This complements low tidal volume in the protective strategy.

Question 18Respiratory failure and mechanical ventilation

A patient is being weaned from mechanical ventilation. Which index is most useful for predicting weaning success?

  1. PaO2/FiO2 ratio above 200
  2. Peak airway pressure above 35 cmH2O
  3. Positive end-expiratory pressure above 10 cmH2O
  4. Rapid shallow breathing index below 105 Correct answer.

Explanation

The rapid shallow breathing index, the ratio of respiratory rate to tidal volume in litres, predicts weaning outcome, with values below about 105 suggesting a favourable chance of success. It integrates breathing pattern and reserve.

Question 19Respiratory failure and mechanical ventilation

Which condition is the most common cause of acute hypercapnic respiratory failure in patients with neuromuscular disease?

  1. Diffuse alveolar haemorrhage
  2. Pulmonary embolism with increased dead space
  3. Respiratory muscle weakness with reduced minute ventilation Correct answer.
  4. High-altitude hypobaric hypoxia

Explanation

Neuromuscular disease impairs the pump, so alveolar hypoventilation develops with a rising PaCO2. The lungs may be intrinsically normal, and support is directed at assisting ventilation.

Question 20Respiratory failure and mechanical ventilation

A ventilated patient with severe ARDS has a PaO2/FiO2 ratio of 120 mmHg. Which combination of measures best reflects current evidence-based management?

  1. High-frequency oscillatory ventilation as first-line therapy
  2. Low tidal volume, adequate PEEP, prone positioning, and conservative fluid balance Correct answer.
  3. Low tidal volume, zero PEEP, and routine high-dose steroids
  4. High tidal volume, low PEEP, supine positioning, and liberal fluids

Explanation

Moderate-to-severe ARDS benefits from a bundle of lung-protective ventilation, adequate PEEP, prone positioning, and a conservative fluid strategy. These measures individually and collectively reduce mortality.

Question 21Respiratory failure and mechanical ventilation

Which finding on a flow-volume loop suggests upper airway obstruction in a spontaneously breathing patient?

  1. Symmetrical reduction of both limbs
  2. Flattening of the inspiratory limb Correct answer.
  3. Concave expiratory limb only
  4. Reduced peak flow with a normal loop shape

Explanation

Variable extrathoracic obstruction classically produces inspiratory limb flattening, whereas variable intrathoracic obstruction flattens the expiratory limb. Fixed obstruction flattens both limbs.

Question 22Respiratory failure and mechanical ventilation

A patient on pressure support ventilation has a tidal volume of 250 mL, respiratory rate of 34 breaths per minute, and accessory muscle use. What does this pattern most likely indicate?

  1. Excessive pressure support causing overdistension
  2. Insufficient pressure support with high respiratory drive Correct answer.
  3. Adequate support with normal breathing pattern
  4. Auto-triggering from a sensitive flow trigger

Explanation

A small tidal volume with a rapid rate and increased effort indicates that the patient is working hard because support is inadequate. The rapid shallow pattern raises the risk of fatigue and weaning failure.

Question 23Respiratory failure and mechanical ventilation

Which statement about permissive hypercapnia during lung-protective ventilation is correct?

  1. Hypercapnia must always be corrected to a normal PaCO2
  2. Permissive hypercapnia is contraindicated in all patients
  3. Bicarbonate should be routinely infused to normalise pH
  4. A gradual rise in PaCO2 is often tolerated to limit lung injury Correct answer.

Explanation

Permissive hypercapnia accepts a raised PaCO2 in exchange for smaller tidal volumes that protect the lung. It is generally tolerated if the pH remains acceptable, though severe acidosis and raised intracranial pressure require caution.

Question 24Respiratory failure and mechanical ventilation

A patient with acute severe asthma is intubated. Which ventilation strategy is most appropriate?

  1. High PEEP to recruit collapsed alveoli
  2. Low respiratory rate with prolonged expiratory time Correct answer.
  3. Large tidal volumes to overcome resistance
  4. High respiratory rate with short expiratory time

Explanation

Severe asthma causes dynamic hyperinflation, so a low respiratory rate with long expiratory time allows complete exhalation and limits auto-PEEP. Tidal volumes should be modest and PEEP kept low to avoid worsening trapping.

Question 25Respiratory failure and mechanical ventilation

Which factor most increases oxygen delivery to tissues when cardiac output is adequate?

  1. Increasing oxygen consumption
  2. Reducing mixed venous oxygen saturation
  3. Increasing arterial oxygen content through haemoglobin and saturation Correct answer.
  4. Decreasing haemoglobin concentration

Explanation

Oxygen delivery is the product of cardiac output and arterial oxygen content, and content depends mainly on haemoglobin and saturation. When output is adequate, improving content raises delivery.

Question 26Respiratory failure and mechanical ventilation

A 62-year-old man with severe community-acquired pneumonia is intubated and ventilated in volume-controlled mode. His peak airway pressure is 38 cmH2O and plateau pressure is 34 cmH2O. Which ventilator change is most appropriate to reduce the risk of ventilator-induced lung injury?

  1. Increase inspiratory flow rate to reduce the inspiratory time
  2. Increase positive end-expiratory pressure to 15 cmH2O
  3. Change to pressure-controlled ventilation with the same tidal volume
  4. Decrease tidal volume to target plateau pressure ≤30 cmH2O Correct answer.

Explanation

A plateau pressure above 30 cmH2O is associated with increased mortality in ARDS, so the priority is to reduce tidal volume (lung-protective ventilation) to bring plateau pressure down. Peak pressure alone is less informative because it also reflects airway resistance. PEEP may be needed but increasing it to 15 cmH2O without addressing the high plateau could worsen overdistension.

Question 27Respiratory failure and mechanical ventilation

A 70-year-old woman with an acute exacerbation of COPD has a pH of 7.28, PaCO2 of 68 mmHg, and PaO2 of 55 mmHg on room air. She is alert and cooperative. Which initial ventilatory support is most appropriate?

  1. High-flow nasal cannula oxygen at 60 L/min
  2. Simple face mask oxygen at 10 L/min
  3. Invasive mechanical ventilation via endotracheal tube
  4. Non-invasive ventilation with bilevel positive airway pressure Correct answer.

Explanation

In acute hypercapnic respiratory acidosis due to COPD exacerbation, non-invasive ventilation (bilevel PAP) is the first-line ventilatory support because it reduces intubation and mortality when the patient is cooperative and can protect the airway. High-flow nasal cannula and simple face mask oxygen do not provide ventilatory assistance for hypercapnia. Invasive ventilation is reserved for failure of NIV or contraindications.

Question 28Respiratory failure and mechanical ventilation

A 45-year-old man with Guillain-Barré syndrome is being monitored in the ICU. His vital capacity is 18 mL/kg, maximum inspiratory pressure is -25 cmH2O, and maximum expiratory pressure is 30 cmH2O. He has difficulty clearing secretions. Which management decision is most appropriate?

  1. Start non-invasive ventilation and avoid intubation
  2. Continue observation and reassess in 12 hours
  3. Proceed to intubation and mechanical ventilation Correct answer.
  4. Give a trial of high-flow nasal oxygen

Explanation

In Guillain-Barré syndrome, a vital capacity below 20 mL/kg, maximum inspiratory pressure less negative than -30 cmH2O, or maximum expiratory pressure below 40 cmH2O predicts impending respiratory failure and need for intubation. The combination of low vital capacity and weak cough with secretion retention is an indication for invasive ventilation. Non-invasive ventilation is not recommended when bulbar function is impaired or secretions cannot be cleared.

Question 29Respiratory failure and mechanical ventilation

A 58-year-old woman with ARDS is ventilated with a tidal volume of 6 mL/kg predicted body weight, PEEP 12 cmH2O, and FiO2 0.8. Her PaO2 is 60 mmHg, and her plateau pressure is 30 cmH2O. Which intervention has the strongest evidence to improve survival in this situation?

  1. Initiate prone positioning for at least 16 hours per day Correct answer.
  2. Increase PEEP to 20 cmH2O
  3. Increase tidal volume to 8 mL/kg to improve ventilation
  4. Start inhaled nitric oxide therapy

Explanation

In moderate-to-severe ARDS (PaO2/FiO2 <150 mmHg), prone positioning for at least 16 hours per day reduces mortality. The patient's PaO2/FiO2 is 75 mmHg, so she meets the criterion. Increasing PEEP may be considered but does not have the same mortality benefit, and increasing tidal volume would be harmful.

Question 30Respiratory failure and mechanical ventilation

A 66-year-old man with severe ARDS is on mechanical ventilation. His arterial blood gas shows pH 7.22, PaCO2 65 mmHg, and PaO2 55 mmHg on FiO2 0.9 and PEEP 14 cmH2O. The ventilator is in volume-controlled mode with tidal volume 6 mL/kg predicted body weight and respiratory rate 28 breaths/min. Which action is most appropriate to improve his acid-base status while maintaining lung-protective ventilation?

  1. Accept permissive hypercapnia and continue current settings Correct answer.
  2. Increase respiratory rate to 35 breaths/min to increase minute ventilation
  3. Administer intravenous sodium bicarbonate to correct the acidosis
  4. Increase tidal volume to 8 mL/kg to increase minute ventilation

Explanation

Permissive hypercapnia is an accepted strategy in ARDS to avoid ventilator-induced lung injury when lung-protective tidal volumes and pressures are used. The pH of 7.22 is tolerable if the patient is hemodynamically stable and there are no contraindications such as raised intracranial pressure. Increasing tidal volume or respiratory rate may exceed lung-protective limits or cause auto-PEEP, and bicarbonate is not routinely indicated for hypercapnic acidosis in this setting.

Question 31Hemodynamic monitoring and shock

A patient in the ICU has a central venous catheter in the internal jugular vein. The transducer is taped at the level of the sternal angle while the patient is sitting at 45 degrees. Which adjustment is required before interpreting the central venous pressure?

  1. Level the transducer at the mid-axillary line at the fourth intercostal space with the patient supine or at a documented angle Correct answer.
  2. Zero the transducer to atmosphere with the stopcock open to the patient and keep the current height
  3. Subtract 5 mmHg from the displayed value to correct for the head-up position
  4. Leave the transducer where it is because the sternal angle is a fixed external reference point

Explanation

Central venous pressure must be referenced to the phlebostatic axis, which lies at the intersection of the fourth intercostal space and the mid-axillary line, with the patient supine or with the angle recorded so trends can be compared. A transducer fixed at the sternal angle overestimates the pressure whenever the patient is upright, and no fixed arithmetic correction is valid. Zeroing to atmosphere is necessary but does not correct the height of the transducer relative to the right atrium.

Question 32Hemodynamic monitoring and shock

Which finding best distinguishes cardiogenic shock from septic shock at the bedside?

  1. Low cardiac index with high filling pressures and cold peripheries Correct answer.
  2. Elevated cardiac index with low systemic vascular resistance
  3. Warm flushed skin with a narrow arteriovenous oxygen difference
  4. Improvement in blood pressure after a 500 mL fluid bolus

Explanation

Cardiogenic shock is characterised by pump failure: a low cardiac index despite adequate or high filling pressures, with cold clammy extremities and raised systemic vascular resistance. Septic shock typically shows a high cardiac index with low vascular resistance and warm peripheries in the early phase. Fluid responsiveness alone does not separate the two, since some cardiogenic patients transiently respond to preload.

Question 33Hemodynamic monitoring and shock

A 70 kg man has a mean arterial pressure of 65 mmHg and a measured cardiac output of 3.5 L/min. What is his systemic vascular resistance in dynes·s·cm⁻⁵?

  1. 2971
  2. 1486 Correct answer.
  3. 743
  4. 520

Explanation

Systemic vascular resistance is calculated as (mean arterial pressure minus central venous pressure) × 80 divided by cardiac output. Assuming a central venous pressure of about 5 mmHg, (65 − 5) × 80 ÷ 3.5 gives approximately 1371, and using a simpler MAP × 80 ÷ CO approximation gives 1486; the answer closest to the accepted range with a low CVP is about 1486. The key point is the inverse relationship between resistance and cardiac output at a given pressure.

Question 34Hemodynamic monitoring and shock

Which waveform feature identifies the dicrotic notch on an arterial pressure trace?

  1. It coincides with the QRS complex on the ECG
  2. It represents the beginning of the anacrotic limb
  3. It occurs at the peak of the systolic upstroke
  4. It marks aortic valve closure at the end of systole Correct answer.

Explanation

The dicrotic notch reflects closure of the aortic valve and the brief reversal of aortic flow at end-systole, dividing the systolic peak from the diastolic runoff. It is a diastolic event and should not be confused with the systolic upstroke or the anacrotic limb, which precedes the peak. Its position shifts with vascular tone and with the site of measurement.

Question 35Hemodynamic monitoring and shock

A ventilated patient with septic shock has a pulse pressure variation of 18% and a stroke volume variation of 16% on 8 mL/kg tidal volume. Which conclusion is most appropriate?

  1. The values indicate that vasopressors should be stopped before any fluid is given
  2. The patient is likely fluid responsive, but the values must be interpreted in the context of sinus rhythm, controlled ventilation and adequate tidal volume Correct answer.
  3. The values are invalid because pulse pressure variation cannot be used in sepsis
  4. The values exclude fluid responsiveness because they exceed 13%

Explanation

Dynamic indices such as pulse pressure variation and stroke volume variation predict fluid responsiveness when the patient is in sinus rhythm, mechanically ventilated with a tidal volume of at least 8 mL/kg and has no spontaneous effort or arrhythmia. Values above roughly 13% suggest preload responsiveness in that context. They do not by themselves prove hypovolaemia and must be integrated with the clinical picture.

Question 36Hemodynamic monitoring and shock

Which condition makes the passive leg raise test unreliable for predicting fluid responsiveness?

  1. Raised intra-abdominal pressure with a compressible inferior vena cava Correct answer.
  2. Adequate tidal volume ventilation with a regular rhythm
  3. A temporary transfer of about 300 mL of blood from the legs to the thorax
  4. Continuous measurement of cardiac output during the manoeuvre

Explanation

The passive leg raise works by autotransfusing roughly 300 mL of venous blood from the legs, acting as a reversible preload challenge. Raised intra-abdominal pressure compresses the inferior vena cava and prevents this transfer, so a negative result cannot be trusted. The test also requires a real-time flow measure and must start from a semi-recumbent position.

Question 37Hemodynamic monitoring and shock

In early hypovolaemic shock from acute haemorrhage, which compensatory change is expected on the venous oximetry and lactate profile?

  1. Falling central venous oxygen saturation with rising lactate Correct answer.
  2. Rising central venous oxygen saturation with rising lactate
  3. Rising central venous oxygen saturation with falling lactate
  4. Unchanged central venous oxygen saturation with normal lactate

Explanation

In hypovolaemic shock, reduced cardiac output and increased oxygen extraction lower central venous oxygen saturation while anaerobic metabolism raises lactate. These changes reflect the mismatch between oxygen delivery and demand. They typically reverse as perfusion is restored.

Question 38Hemodynamic monitoring and shock

A patient with a pulmonary artery catheter has a cardiac output of 6.0 L/min, mean pulmonary artery pressure of 35 mmHg and pulmonary artery occlusion pressure of 12 mmHg. What is the pulmonary vascular resistance in Wood units?

  1. 1.9
  2. 3.8 Correct answer.
  3. 5.8
  4. 2.3

Explanation

Pulmonary vascular resistance in Wood units equals mean pulmonary artery pressure minus pulmonary artery occlusion pressure, divided by cardiac output. Here (35 − 12) ÷ 6 gives about 3.8 Wood units. The occlusion pressure is used as the downstream pressure because it approximates left atrial pressure.

Question 39Hemodynamic monitoring and shock

Which measurement best estimates left ventricular preload in a patient with severe aortic regurgitation and a pulmonary artery catheter?

  1. Left ventricular end-diastolic volume index Correct answer.
  2. Pulmonary artery diastolic pressure
  3. Right atrial pressure
  4. Pulmonary artery occlusion pressure

Explanation

Pressure measurements such as pulmonary artery occlusion pressure are unreliable estimates of preload when ventricular compliance is abnormal or when aortic regurgitation distorts diastolic pressures. Volumetric indices, particularly left ventricular end-diastolic volume index, reflect actual chamber filling more directly. This distinction matters when titrating fluids in valvular disease.

Question 40Hemodynamic monitoring and shock

Which finding on bedside echocardiography suggests cardiac tamponade rather than isolated right ventricular infarction?

  1. Mitral inflow E wave greater than A wave
  2. Dilated right ventricle with preserved pericardial space and normal inferior vena cava
  3. Global hypokinesis with a small pericardial effusion
  4. Right atrial systolic collapse and a dilated non-collapsing inferior vena cava with a pericardial effusion Correct answer.

Explanation

Tamponade is suggested by a pericardial effusion with chamber compression, typically right atrial systolic collapse, right ventricular diastolic collapse and a plethoric inferior vena cava that does not vary with respiration. Right ventricular infarction can also raise right-sided pressures but lacks the effusion and compressive findings. Echo therefore separates the two causes of obstructive or right-sided shock.

Question 41Hemodynamic monitoring and shock

A patient with massive pulmonary embolism is hypotensive with a distended right ventricle on echo. Which haemodynamic pattern is most consistent?

  1. Low right atrial pressure, low pulmonary artery occlusion pressure and normal cardiac output
  2. Low right atrial pressure, high pulmonary artery occlusion pressure and high cardiac output
  3. High right atrial pressure, high pulmonary artery occlusion pressure and high cardiac output
  4. High right atrial pressure, low pulmonary artery occlusion pressure and low cardiac output Correct answer.

Explanation

Acute right ventricular failure from pulmonary embolism raises right-sided pressures while reducing left ventricular filling, so right atrial pressure is high, the occlusion pressure is low and cardiac output falls. The combination of high right atrial pressure with a low occlusion pressure is the classic obstructive pattern. Fluid loading is used cautiously because a distended right ventricle can worsen septal shift.

Question 42Hemodynamic monitoring and shock

Which statement about the use of capillary refill time as a resuscitation target in septic shock is most accurate?

  1. Capillary refill time correlates only with central venous pressure
  2. Capillary refill time is unreliable in adults and should not be used at all
  3. A prolonged capillary refill time of more than 3 seconds identifies peripheral hypoperfusion and can guide resuscitation alongside lactate Correct answer.
  4. A normal capillary refill time excludes tissue hypoperfusion

Explanation

Capillary refill time measured on the index fingertip is a simple marker of peripheral perfusion, and a value above about 3 seconds has been associated with worse outcomes and can be used to titrate resuscitation. It complements rather than replaces lactate and other perfusion markers. Normal values do not guarantee adequate organ perfusion because regional hypoperfusion can coexist.

Question 43Hemodynamic monitoring and shock

Which parameter is derived directly from the arterial pressure waveform by the pulse contour method and requires calibration or autocalibration to remain accurate?

  1. Cardiac output Correct answer.
  2. Central venous pressure
  3. Stroke volume variation
  4. Mixed venous oxygen saturation

Explanation

Pulse contour analysis estimates cardiac output continuously from the arterial waveform by integrating the systolic area under the curve, but the estimate drifts as vascular compliance and resistance change, so periodic calibration or autocalibration is needed. Stroke volume variation is also derived from the waveform but describes preload responsiveness rather than absolute flow. Central venous pressure and mixed venous saturation come from other catheters.

Question 44Hemodynamic monitoring and shock

A patient has a mean arterial pressure of 55 mmHg with a normal cardiac output and low systemic vascular resistance. Which initial vasopressor is recommended for septic shock according to current guidelines?

  1. Dopamine
  2. Norepinephrine Correct answer.
  3. Phenylephrine
  4. Vasopressin as a first-line agent

Explanation

Norepinephrine is the first-line vasopressor in septic shock because it raises mean arterial pressure with less tachyarrhythmia than dopamine and preserves splanchnic perfusion better than phenylephrine. Vasopressin is added as a second agent to reduce norepinephrine requirements rather than started first. Dopamine is reserved for selected bradycardic patients.

Question 45Hemodynamic monitoring and shock

Which value of central venous oxygen saturation is most consistent with adequate global oxygen delivery in a resuscitated septic patient?

  1. 55%
  2. 45%
  3. 70% Correct answer.
  4. 95%

Explanation

Central venous oxygen saturation of about 70% is the usual target range in resuscitated septic patients, reflecting a balance between oxygen delivery and consumption. Values near 45% or 55% suggest increased extraction and inadequate delivery. A value near 95% may indicate impaired tissue oxygen utilisation or a very high flow state rather than adequacy.

Question 46Hemodynamic monitoring and shock

A patient with cirrhosis and septic shock has a high cardiac output, low systemic vascular resistance and a normal lactate. Which haemodynamic profile does this represent?

  1. Distributive shock with a hyperdynamic circulation Correct answer.
  2. Cardiogenic shock with compensated output
  3. Obstructive shock from pulmonary embolism
  4. Hypovolaemic shock with vasoconstriction

Explanation

Cirrhosis produces a hyperdynamic circulation with splanchnic vasodilation, so septic shock superimposes on an already low-resistance state, giving high output and low resistance. A normal lactate does not exclude shock, since lactate clearance and production are both altered in liver disease. The pattern is distributive rather than cardiogenic, hypovolaemic or obstructive.

Question 47Hemodynamic monitoring and shock

Which statement about the arterial pressure waveform in a patient with a radial arterial line and severe vasoconstriction is correct?

  1. The dicrotic notch disappears when systemic vascular resistance rises
  2. The radial systolic pressure may underestimate central aortic pressure while diastolic pressure is overestimated Correct answer.
  3. The radial systolic pressure always equals central aortic pressure
  4. Damping shortens the systolic upstroke and lowers the peak

Explanation

Peripheral amplification means the radial systolic peak can be higher than the aortic value in normal states, but with severe vasoconstriction and a stiff vasculature the peripheral trace can distort, and damping or resonance alters the relationship. Clinicians should interpret peripheral pressures cautiously and treat the trend and mean pressure as more reliable than the systolic peak. Mean arterial pressure is the least affected by waveform distortion.

Question 48Hemodynamic monitoring and shock

Which finding on a central venous pressure waveform indicates that the catheter tip is in the right ventricle?

  1. Prominent a and v waves with a normal x descent
  2. A single large v wave with a slow y descent
  3. Large c-v waves replacing the normal a wave pattern with a rapid systolic rise Correct answer.
  4. Absence of the a wave in atrial fibrillation

Explanation

A central venous catheter that has advanced into the right ventricle produces a ventricular pressure waveform with large c-v waves and a rapid systolic rise, and the tracing resembles an arterial or ventricular trace. The correct action is to withdraw the catheter and confirm the tip position. Normal atrial waveforms show distinct a, c and v waves with x and y descents.

Question 49Hemodynamic monitoring and shock

Which condition is a recognised cause of falsely low pulmonary artery occlusion pressure?

  1. Positive end-expiratory pressure of 15 cmH₂O
  2. Placement of the transducer above the phlebostatic axis
  3. Mitral stenosis with a large v wave
  4. Catheter tip in the pulmonary artery branch with the balloon inflated in a West zone 1 lung region Correct answer.

Explanation

Occlusion pressure reflects left atrial pressure only when the catheter tip lies in a lung region where pulmonary venous pressure exceeds alveolar pressure, that is West zone 3. In zone 1 the alveolar pressure exceeds venous pressure, so the reading reflects airway pressure and is falsely low or uninterpretable. The balloon should be inflated only briefly and the tracing confirmed.

Question 50Hemodynamic monitoring and shock

Which statement best describes the use of the shock index in early triage of the bleeding trauma patient?

  1. Shock index is mean arterial pressure minus heart rate and is used only in sepsis
  2. Shock index is heart rate divided by systolic pressure and rises above 0.9 before hypotension appears Correct answer.
  3. Shock index is systolic pressure divided by heart rate and falls with worsening shock
  4. Shock index equals cardiac output divided by systemic vascular resistance

Explanation

The shock index is the ratio of heart rate to systolic blood pressure, and a value above about 0.9 can identify occult hypoperfusion before conventional vital signs become abnormal. It is a simple triage tool that complements lactate and base deficit. It does not replace formal haemodynamic assessment.