CCRN Respiratory Practice Test

25 practice questions

Choose an answer, then check it under Show answer.

1. Question 1 of 25Easy

   A mechanically ventilated patient with a history of severe asthma develops sudden tachypnea and elevated peak inspiratory pressures. Continuous capnography shows an elongated, upward-sloping phase III alveolar plateau resembling a shark fin. How should the nurse interpret this capnogram?

   1. AA. Spontaneous patient effort during the expiratory phase of a mandatory breath
   2. BB. Rebreathing of exhaled carbon dioxide due to an incompetent expiratory valve
   3. CC. Loss of an effective seal around the endotracheal tube cuff
   4. DD. Persistent bronchospasm causing prolonged expiratory airflow obstruction
   Show answer to question 1

   Answer: D. Persistent bronchospasm causing prolonged expiratory airflow obstruction

   The characteristic shark-fin capnogram reflects uneven alveolar emptying and prolonged expiratory airflow resistance caused by bronchospasm or airflow obstruction. Patient effort during mechanical exhalation produces a downward dip in the plateau known as a curare cleft rather than a shark fin. Rebreathing exhaled carbon dioxide raises the baseline above zero during inspiration, and an endotracheal cuff leak typically causes a low, truncated waveform.

2. Question 2 of 25Hard

   Immediately after intubation for status asthmaticus, a 31-year-old woman is being manually ventilated with a bag at about 30 breaths/min. Her blood pressure falls from 128/76 to 70/40 mm Hg, her neck veins distend, and breath sounds are diminished on both sides. Which action should the nurse take first?

   1. AA. Pause bagging briefly so that trapped air can be fully exhaled
   2. BB. Bag faster with larger breaths to correct her rising hypercapnia
   3. CC. Prepare for bilateral needle decompression of the chest
   4. DD. Add PEEP to the bag to hold the narrowed airways open
   Show answer to question 2

   Answer: A. Pause bagging briefly so that trapped air can be fully exhaled

   Rapid bagging leaves too little time to exhale through narrowed airways, so air is trapped (dynamic hyperinflation with auto-PEEP), intrathoracic pressure rises and venous return falls. Briefly pausing ventilation to let the lungs empty, then ventilating at a slower rate with a longer expiratory time, usually restores the blood pressure quickly, and tension pneumothorax is considered if it does not.

   Why the other options are wrong

   • BFaster, larger breaths would trap more air and further reduce venous return and blood pressure.
   • CBilateral tension pneumothorax is much less likely than air trapping here and is pursued only if a pause in ventilation fails.
   • DAdding external PEEP during controlled ventilation raises end-expiratory lung volume and can worsen hyperinflation.

3. Question 3 of 25Hard

   A 70-year-old man on volume assist-control ventilation triggers a high-pressure alarm. His peak inspiratory pressure has risen from 29 to 46 cm H2O, while his plateau pressure is unchanged at 22 cm H2O. Coarse rhonchi are heard over the trachea and both lungs, breath sounds are present on both sides, and his SpO2 has fallen from 95% to 90%. Which action should the nurse take first?

   1. AA. Prepare for needle decompression of the chest
   2. BB. Increase the PEEP to recruit collapsed alveoli
   3. CC. Suction the endotracheal tube to clear the airway
   4. DD. Lower the tidal volume to reduce plateau pressure
   Show answer to question 3

   Answer: C. Suction the endotracheal tube to clear the airway

   A higher peak pressure with an unchanged plateau pressure means more pressure is needed to overcome airway resistance while lung compliance is unchanged. With coarse rhonchi, secretions are the likely cause, so suctioning comes first; biting, a kinked tube and bronchospasm are other resistance problems to check.

   Why the other options are wrong

   • AA tension pneumothorax lowers compliance, so the plateau pressure would rise and breath sounds would be diminished on one side.
   • BMore PEEP does not relieve airway obstruction and would raise both peak and plateau pressures.
   • DThe plateau pressure is unchanged at 22 cm H2O, so lowering the tidal volume does not address the cause.

4. Question 4 of 25Medium

   A 58-year-old mechanically ventilated patient has an endotracheal tube equipped with a subglottic secretion drainage port. Which action by the nurse represents evidence-based practice for preventing ventilator-associated pneumonia (VAP)?

   1. AA. Discontinue subglottic suctioning once the patient is transitioned to pressure support ventilation.
   2. BB. Apply continuous or intermittent suction to the subglottic port at recommended pressures.
   3. CC. Deflate the endotracheal tube cuff briefly prior to initiating subglottic suctioning.
   4. DD. Instill normal saline down the subglottic lumen every 4 hours to maintain patency.
   Show answer to question 4

   Answer: B. Apply continuous or intermittent suction to the subglottic port at recommended pressures.

   Continuous or intermittent suctioning of the subglottic space removes pooled secretions above the cuff and significantly reduces the incidence of VAP. Routine saline instillation down the subglottic port is not recommended and can increase the risk of introducing bacteria into the lower airway. Deflating the cuff would allow pooled secretions to drain into the trachea.

5. Question 5 of 25Easy

   A patient who was extubated 30 minutes ago suddenly exhibits high-pitched inspiratory sounds, intercostal retractions, and nasal flaring. The nurse recognizes these findings as hallmarks of which pathophysiology?

   1. AA. Extrathoracic upper airway narrowing
   2. BB. Bronchospasm in the lower terminal airways
   3. CC. Alveolar collapse secondary to atelectasis
   4. DD. Bilateral diaphragmatic paresis
   Show answer to question 5

   Answer: A. Extrathoracic upper airway narrowing

   Inspiratory stridor and intercostal retractions after extubation reflect turbulent gas flow through a narrowed, extrathoracic upper airway, typically caused by glottic or subglottic edema. In contrast, lower airway bronchospasm characteristically causes expiratory wheezing and prolonged exhalation rather than high-pitched inspiratory stridor.

6. Question 6 of 25Medium

   After being turned, a 63-year-old woman's endotracheal tube marking at the lips reads 27 cm; its position was confirmed at 23 cm after intubation. Breath sounds are now diminished on the left, her peak inspiratory pressure has risen, and her SpO2 has fallen from 95% to 88%. The capnography waveform and her blood pressure are unchanged. What is the most likely cause?

   1. AA. The tube has slipped out of the trachea into the esophagus
   2. BB. A left tension pneumothorax has developed during the turn
   3. CC. The tube has advanced into the right mainstem bronchus
   4. DD. The cuff has ruptured and is leaking air around the tube
   Show answer to question 6

   Answer: C. The tube has advanced into the right mainstem bronchus

   The tube now sits 4 cm deeper than its confirmed position, and the right mainstem bronchus is the straighter path, so the tip has most likely entered it. Ventilating only the right lung raises peak pressure, diminishes left-sided breath sounds and causes hypoxemia, so the tube is pulled back to its confirmed depth and rechecked.

   Why the other options are wrong

   • AEsophageal displacement would flatten the capnography waveform, and the marking shows the tube moved deeper, not out.
   • BA tension pneumothorax would usually lower blood pressure, and it would not explain the tube now sitting 4 cm deeper.
   • DA cuff leak lowers airway pressure and exhaled volume rather than raising peak pressure.

7. Question 7 of 25Easy

   A nurse is evaluating a patient receiving pressure support ventilation (PSV) as part of an assessment of readiness for extubation. What mechanism does the ventilator use to end inspiration and cycle into exhalation during this mode?

   1. AA. The expiration of a fixed inspiratory time interval set on the console
   2. BB. A drop in circuit pressure below the set positive end-expiratory pressure
   3. CC. A decline in inspiratory flow to a predetermined percentage of peak flow
   4. DD. The delivery of a predetermined target tidal volume into the airway
   Show answer to question 7

   Answer: C. A decline in inspiratory flow to a predetermined percentage of peak flow

   Pressure support ventilation is a patient-triggered, pressure-limited, and flow-cycled mode. Inspiration terminates and exhalation begins when the patient's inspiratory flow decays to a preset threshold, typically 25% of the peak inspiratory flow. Cycling based on a fixed inspiratory time characterizes time-cycled modes such as pressure control ventilation, not pressure support.

8. Question 8 of 25Hard

   During cardiopulmonary resuscitation, an adult patient is intubated. A colorimetric end-tidal carbon dioxide detector attached to the tube fails to change color and remains purple. Auscultation reveals faint, symmetric chest sounds and epigastric silence. Which interpretation is most accurate?

   1. AA. The colorimetric detector may be falsely negative because of critically low pulmonary blood flow.
   2. BB. Systemic metabolic acidosis prevents the chemical sensor from detecting expired carbon dioxide.
   3. CC. The endotracheal tube is definitely in the esophagus and requires immediate removal.
   4. DD. High fractions of delivered supplemental oxygen deactivate the colorimetric chemical matrix.
   Show answer to question 8

   Answer: A. The colorimetric detector may be falsely negative because of critically low pulmonary blood flow.

   Colorimetric detectors rely on pulmonary blood flow to transport carbon dioxide to the lungs for exhalation; during low-flow states such as cardiac arrest, expired carbon dioxide may fall below the detection threshold, producing a false-negative reading despite correct tracheal placement. In this situation, secondary methods such as video laryngoscopy, ultrasound, or an esophageal detector device should be used before immediately assuming esophageal intubation.

9. Question 9 of 25Hard

   A patient with chronic hypercapnia secondary to severe emphysema and a known baseline PaCO2 of 65 mm Hg is intubated for acute pneumonia. In the intensive care unit, the mechanical ventilator is set with a high minute ventilation, rapidly reducing the PaCO2 to 38 mm Hg within two hours. The repeat arterial blood gas (ABG) reveals: pH 7.56, PaCO2 38 mm Hg, and HCO3 34 mEq/L. What is the primary reason for this patient's alkalemia?

   1. AA. Renal tubular retention of chloride ions induced by acute hyperventilation
   2. BB. Rapid elimination of carbon dioxide outpaces slower renal bicarbonate excretion
   3. CC. Intracellular shift of carbonic acid driven by high alveolar oxygen tension
   4. DD. Excessive gastrointestinal loss of hydrogen ions from endotracheal intubation
   Show answer to question 9

   Answer: B. Rapid elimination of carbon dioxide outpaces slower renal bicarbonate excretion

   This patient has developed acute post-hypercapnic metabolic alkalosis because the ventilator rapidly eliminated carbon dioxide while the kidneys, which had retained substantial bicarbonate to compensate for chronic baseline hypercapnia, require days to excrete excess bicarbonate. Renal retention of chloride is incorrect because the kidneys actually excrete chloride and conserve bicarbonate during chronic compensation, and post-hypercapnic alkalosis is often maintained by a concurrent chloride deficit.

10. Question 10 of 25Easy

    A nurse evaluates a patient with chronic hypercapnic respiratory failure who is receiving supplemental oxygen for a lower respiratory tract infection. Which clinical finding should prompt the nurse to suspect worsening acute carbon dioxide retention?

    1. AA. Pupillary constriction and hyperreflexia
    2. BB. Severe circumoral cyanosis and inspiratory stridor
    3. CC. Asterixis and progressive somnolence
    4. DD. Pallor and cool, clammy extremities
    Show answer to question 10

    Answer: C. Asterixis and progressive somnolence

    Acute hypercapnia induces cerebral vasodilation and metabolic encephalopathy, which characteristically manifest as asterixis (flapping tremor of the hands), confusion, lethargy, headache, and progressive somnolence. Pallor and cool extremities indicate peripheral vasoconstriction, whereas hypercapnia causes peripheral vasodilation resulting in warm, flushed skin and bounding pulses.

11. Question 11 of 25Easy

    A 62-year-old mechanically ventilated patient with septic shock has worsening bilateral pulmonary infiltrates. Current ventilator settings include an FiO2 of 0.85 and a positive end-expiratory pressure (PEEP) of 12 cm H2O. The arterial blood gas shows: pH 7.30, PaCO2 49 mm Hg, PaO2 68 mm Hg, and HCO3 23 mEq/L. Based on the Berlin definition, how should the nurse classify the severity of the patient's ARDS?

    1. AA. Moderate ARDS
    2. BB. Refractory ARDS
    3. CC. Severe ARDS
    4. DD. Mild ARDS
    Show answer to question 11

    Answer: C. Severe ARDS

    The PaO2/FiO2 ratio is calculated by dividing the PaO2 by the decimal fraction of inspired oxygen (68 divided by 0.85 equals 80 mm Hg). According to the Berlin criteria, ARDS is categorized as mild (201 to 300 mm Hg), moderate (101 to 200 mm Hg), or severe (100 mm Hg or less) when evaluated on a minimum PEEP of 5 cm H2O. Moderate ARDS is incorrect because a ratio of 80 mm Hg falls below the 101 mm Hg threshold.

12. Question 12 of 25Hard

    A patient with acute respiratory failure has endotracheal fluid sampled to help differentiate between cardiogenic and noncardiogenic pulmonary edema. Which laboratory finding in the edema fluid most strongly indicates noncardiogenic pulmonary edema?

    1. AA. Edema fluid-to-plasma protein ratio greater than 0.7
    2. BB. Edema fluid-to-plasma protein ratio less than 0.5
    3. CC. Absence of white blood cells on microscopic analysis
    4. DD. Markedly elevated brain natriuretic peptide level
    Show answer to question 12

    Answer: A. Edema fluid-to-plasma protein ratio greater than 0.7

    An edema fluid-to-plasma protein ratio greater than 0.65 to 0.7 reflects high-permeability pulmonary edema typical of acute lung injury or ARDS, where alveolar-capillary membrane disruption allows large protein molecules to leak into the alveoli. A low protein ratio (less than 0.5) is characteristic of hydrostatic or cardiogenic pulmonary edema, where intact membranes retain large proteins in the vascular space.

13. Question 13 of 25Medium

    A 68-year-old man with extensive left lower lobe pneumonia has an SpO2 of 89% on 6 L/min of oxygen by nasal cannula. How should the nurse position him to improve his oxygenation?

    1. AA. On his left side, so the affected lung is dependent
    2. BB. Supine and flat, so both lungs are perfused equally
    3. CC. In Trendelenburg, so secretions drain toward the trachea
    4. DD. On his right side, so the healthier lung is dependent
    Show answer to question 13

    Answer: D. On his right side, so the healthier lung is dependent

    Gravity directs more pulmonary blood flow to the dependent lung, so placing the healthier lung down matches perfusion with the better-ventilated alveoli and improves oxygenation. The nurse reassesses the SpO2 and work of breathing after each position change.

    Why the other options are wrong

    • APlacing the consolidated lung down sends more blood to poorly ventilated alveoli and increases shunt.
    • BLying flat reduces lung volumes and raises aspiration risk without improving ventilation-perfusion matching.
    • CHead-down positioning pushes the diaphragm up, reduces lung volumes and increases aspiration risk.

14. Question 14 of 25Easy

    A mechanically ventilated patient with severe pneumonia has a plateau pressure of 36 cm H2O. Physical assessment reveals new swelling and palpable crepitus across the anterior neck and upper thorax. Which complication should the nurse anticipate immediately?

    1. AA. Tracheoesophageal fistula
    2. BB. Acute pulmonary edema
    3. CC. Superior vena cava syndrome
    4. DD. Pulmonary barotrauma
    Show answer to question 14

    Answer: D. Pulmonary barotrauma

    Palpable crepitus in the neck and upper thorax indicates subcutaneous emphysema, a hallmark presentation of pulmonary barotrauma caused by alveolar rupture under excessive distending pressures (plateau pressure greater than 30 cm H2O). This air can dissect along bronchovascular sheaths into the mediastinum and chest wall, often coexisting with or preceding a pneumothorax. Tracheoesophageal fistula typically presents with aspiration and gastric distention rather than acute, isolated upper chest subcutaneous crepitus.

15. Question 15 of 25Medium

    A mechanically ventilated patient with severe status asthmaticus is suspected of having significant dynamic hyperinflation. Which bedside ventilator maneuver should the critical care nurse perform to quantify the patient's intrinsic positive end-expiratory pressure (auto-PEEP)?

    1. AA. Perform an end-inspiratory hold during volume control ventilation
    2. BB. Gradually increase the applied extrinsic positive end-expiratory pressure
    3. CC. Measure the transpulmonary pressure gradient at peak inflation
    4. DD. Perform an end-expiratory hold on a passive patient
    Show answer to question 15

    Answer: D. Perform an end-expiratory hold on a passive patient

    An end-expiratory hold closes both inspiratory and expiratory valves at the end of the set exhalation phase, allowing alveolar pressure and ventilator circuit pressure to equilibrate so that total PEEP can be measured; subtracting set extrinsic PEEP yields intrinsic PEEP (auto-PEEP). An end-inspiratory hold is used to measure plateau pressure and assess static compliance, not intrinsic PEEP.

16. Question 16 of 25Easy

    A 28-year-old trauma patient has a right-sided chest tube placed for a traumatic hemothorax. The initial drainage is 800 mL of dark red blood. Over the next three consecutive hours, the chest drainage output is 260 mL, 240 mL, and 230 mL, respectively. The patient's blood pressure is 88/54 mm Hg and heart rate is 122 beats/min. Which intervention is indicated next?

    1. AA. Urgent surgical thoracotomy
    2. BB. Instilling intrapleural tranexamic acid
    3. CC. Increasing wall suction pressure to negative 40 cm H2O
    4. DD. Clamping the chest tube to allow a clot to form
    Show answer to question 16

    Answer: A. Urgent surgical thoracotomy

    Indications for urgent thoracotomy in traumatic hemothorax include an immediate chest tube evacuation of at least 1500 mL of blood or continuous chest tube drainage exceeding 200 mL/hr for 2 to 4 consecutive hours accompanied by hemodynamic instability. Clamping a draining chest tube in an active hemothorax can convert the condition into a tension hemothorax and is contraindicated. Increasing negative suction or instilling tranexamic acid intrapleurally does not address active surgical bleeding.

17. Question 17 of 25Hard

    Which mechanism explains why severe right ventricular dilation in acute pulmonary embolism directly causes systemic hypotension and low cardiac output?

    1. AA. Accelerated mitral valve closure caused by elevated left atrial blood volume
    2. BB. Leftward shift of the interventricular septum that restricts left ventricular end-diastolic filling
    3. CC. Sudden peripheral vasodilation caused by reflex vagal stimulation in the pulmonary vasculature
    4. DD. Impaired coronary artery perfusion driven primarily by elevated left ventricular end-diastolic pressure
    Show answer to question 17

    Answer: B. Leftward shift of the interventricular septum that restricts left ventricular end-diastolic filling

    As the thin-walled right ventricle acutely dilates against severe pulmonary vascular resistance, the interventricular septum shifts toward the left ventricle (ventricular interdependence). This septal flattening and paradoxical motion physically impinges on the left ventricular cavity, severely diminishing left ventricular end-diastolic volume and subsequent stroke volume, precipitating obstructive shock. Peripheral vasodilation is not the primary driver, as systemic vascular resistance typically rises compensatorily in response to low cardiac output.

18. Question 18 of 25Medium

    A patient with an established cuffed tracheostomy receiving continuous enteral nutrition has recurring episodes of purulent, tube-feed-colored secretions during tracheal suctioning. The nurse also notes persistent abdominal distension during mechanical ventilation despite a properly inflated cuff. Which diagnostic evaluation should the nurse anticipate?

    1. AA. Bronchoscopy to evaluate for a tracheoesophageal fistula
    2. BB. Chest radiography to rule out mucus plugging
    3. CC. Arterial blood gas analysis to assess ventilation-perfusion mismatch
    4. DD. Barium swallow study after immediate extubation
    Show answer to question 18

    Answer: A. Bronchoscopy to evaluate for a tracheoesophageal fistula

    The presence of enteral feedings in tracheal secretions accompanied by air entry into the stomach (abdominal distension) despite an inflated tracheostomy cuff is classic for an acquired tracheoesophageal fistula (TEF). Direct visualization via bronchoscopy and endoscopy is the definitive method to confirm the location and extent of the fistula. Mucus plugging does not explain enteral contents in the airway, and extubating a critically ill patient for a barium study is unsafe.

19. Question 19 of 25Medium

    A nurse is assessing a spontaneously breathing patient who has a right pleural chest tube connected to water seal without suction. How should the fluid level in the water-seal chamber normally fluctuate during the respiratory cycle?

    1. AA. Falls during inspiration and rises during expiration
    2. BB. Rises during inspiration and falls during expiration
    3. CC. Rises during both phases of inspiration and expiration
    4. DD. Remains stationary during inspiration and drops during expiration
    Show answer to question 19

    Answer: B. Rises during inspiration and falls during expiration

    In a spontaneously breathing patient, negative intrathoracic pressure generated during inspiration draws fluid upward into the water-seal column, causing the fluid level to rise. Expiration increases intrathoracic pressure relative to the atmosphere, pushing fluid downward and allowing the level to fall. A fall during inspiration and rise during expiration is the opposite pattern, which occurs in patients receiving positive-pressure mechanical ventilation.

20. Question 20 of 25Medium

    A 31-year-old man with a gunshot wound to the left chest has a chest tube inserted, and 1,800 mL of blood drains immediately. Over the next hour another 350 mL drains, his blood pressure is 82/50 mm Hg despite transfusion, and his heart rate is 136/min. Which intervention should the nurse anticipate?

    1. AA. Clamping of the chest tube to tamponade the bleeding
    2. BB. Urgent operative thoracotomy to stop the bleeding
    3. CC. A second chest tube and a repeat chest x-ray in 1 hour
    4. DD. Autotransfusion of drained blood and reassessment in 4 hours
    Show answer to question 20

    Answer: B. Urgent operative thoracotomy to stop the bleeding

    An immediate chest tube output of about 1,500 mL or more, or continued brisk bleeding with hemodynamic instability, indicates a massive hemothorax that needs surgical control. This patient has both, so the nurse anticipates urgent thoracotomy while resuscitation with blood products continues.

    Why the other options are wrong

    • AClamping does not stop intrathoracic bleeding and lets blood collect and compress the lung and heart.
    • CAnother tube would drain more blood without controlling the source, and waiting for imaging delays surgery.
    • DAutotransfusion can support resuscitation but does not stop the bleeding, and waiting 4 hours in shock is unsafe.

21. Question 21 of 25Medium

    A 50-year-old man with severe ARDS has persistent ventilator dyssynchrony despite sedation, and the provider orders a continuous infusion of cisatracurium. Which nursing action is the priority before the infusion is started?

    1. AA. Stop the sedative infusion, because paralysis will end the dyssynchrony
    2. BB. Confirm that he is deeply sedated and receiving adequate analgesia
    3. CC. Stop routine eye care, because the blink reflex will remain intact
    4. DD. Plan to measure his sedation level with the RASS once he is paralyzed
    Show answer to question 21

    Answer: B. Confirm that he is deeply sedated and receiving adequate analgesia

    Neuromuscular blockers paralyze skeletal muscle but provide no sedation, amnesia or analgesia, so a patient paralyzed without deep sedation may be awake and in pain yet unable to show it. Deep sedation and analgesia must be in place before the blocker starts and must continue throughout the infusion.

    Why the other options are wrong

    • AStopping sedation would leave him paralyzed and possibly aware, a serious and preventable harm.
    • CParalysis abolishes blinking and lid closure, so eye lubrication and lid care are needed to prevent corneal injury.
    • DThe RASS depends on the patient's movement and response, so it cannot measure sedation depth during paralysis.

22. Question 22 of 25Hard

    Two hours following an ultrasound-guided thoracentesis, a patient becomes acutely pale, diaphoretic, and tachycardic with a blood pressure of 78/48 mmHg. Breath sounds on the punctured side are absent, and bedside ultrasound demonstrates a massive re-accumulation of dense, swirling fluid. Which vascular complication most likely occurred?

    1. AA. Internal mammary artery rupture
    2. BB. Subclavian vein cannulation
    3. CC. Intercostal artery laceration
    4. DD. Aortic dissection
    Show answer to question 22

    Answer: C. Intercostal artery laceration

    Intercostal artery laceration is a known mechanical complication of thoracentesis that leads to rapid arterial hemothorax, presenting with hemorrhagic shock, absent breath sounds, and massive intrapleural fluid re-accumulation. The intercostal vessels run immediately below each rib, making needle placement along the inferior border of the rib a significant risk factor. The subclavian and internal mammary arteries are located more anteriorly and medially and are not traversed during standard posterior or lateral thoracentesis.

23. Question 23 of 25Medium

    A patient receiving invasive mechanical ventilation suddenly exhibits high-pressure alarms and acute hypoxemia. The nurse attempts manual bag ventilation and encounters severe resistance with no visible chest rise. An in-line suction catheter cannot be advanced beyond the distal tip of the endotracheal tube. Which action should the nurse take immediately?

    1. AA. Perform needle cricothyroidotomy to secure a subglottic airway
    2. BB. Instill 10 mL of sterile water and attempt forceful suctioning
    3. CC. Increase the manual resuscitation bag pressure to overcome resistance
    4. DD. Deflate the endotracheal cuff and immediately extubate the patient
    Show answer to question 23

    Answer: D. Deflate the endotracheal cuff and immediately extubate the patient

    Inability to pass a suction catheter beyond the tip of the endotracheal tube combined with complete resistance to manual ventilation and absent chest rise indicates complete obstruction of the artificial airway, typically by a dried mucous plug, severe herniated cuff, or kinked tube. Immediate extubation followed by manual bag-valve-mask ventilation with an oral airway is required to re-establish ventilation and prevent asphyxiation. Attempting to force suction catheters, instilling fluid, or forcing manual ventilation wastes critical seconds during total airway obstruction.

24. Question 24 of 25Medium

    A patient with severe bilateral pneumonia is receiving supplemental oxygen via a high-flow nasal cannula at 60 L/min and FiO2 0.80. The baseline arterial blood gas shows a PaO2 of 54 mmHg. The nurse increases the FiO2 to 1.00, but a repeat blood gas 30 minutes later reveals a PaO2 of 57 mmHg. Which physiological mechanism best explains this lack of response to increased supplemental oxygen?

    1. AA. Impaired alveolar-capillary membrane diffusion
    2. BB. Low ventilation-perfusion ratio mismatch
    3. CC. Increased physiological dead-space ventilation
    4. DD. Severe right-to-left intrapulmonary shunt
    Show answer to question 24

    Answer: D. Severe right-to-left intrapulmonary shunt

    Refractory hypoxemia that fails to respond significantly to escalating concentrations of inspired oxygen is the hallmark of an intrapulmonary right-to-left shunt, where deoxygenated capillary blood traverses unventilated or consolidated alveoli without participating in gas exchange. Low ventilation-perfusion mismatch and diffusion limitations typically show substantial improvement in arterial oxygen tension when high concentrations of supplemental oxygen are administered. Dead-space ventilation impairs carbon dioxide elimination rather than producing oxygen-refractory hypoxemia.

25. Question 25 of 25Medium

    A patient receives topical benzocaine spray prior to transesophageal echocardiography and subsequent bronchoscopy. Shortly after the procedure, the patient becomes cyanotic and the continuous pulse oximeter reads 85%. The arterial blood gas demonstrates a PaO2 of 210 mm Hg on a high-flow mask, and the blood sample appears dark chocolate-brown. Which treatment should the nurse anticipate?

    1. AA. Inhalation of nebulized racemic epinephrine
    2. BB. Emergent needle thoracostomy over the second intercostal space
    3. CC. Intravenous administration of methylene blue
    4. DD. Urgent exchange of the high-flow mask for noninvasive positive pressure ventilation
    Show answer to question 25

    Answer: C. Intravenous administration of methylene blue

    Topical local anesthetics like benzocaine can oxidize hemoglobin iron from the ferrous (Fe2+) to the ferric (Fe3+) state, generating methemoglobinemia characterized by cyanosis refractory to oxygen, a pulse oximeter reading refractory near 85%, chocolate-brown blood, and a falsely reassuring high dissolved PaO2; intravenous methylene blue is the definitive antidote. Noninvasive positive pressure ventilation or racemic epinephrine treats hypoxemic failure or upper airway stridor, neither of which addresses the chemically altered, non-functional hemoglobin.

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