Respirology & Ventilator – Full Test

You are the attending physician in a critical care unit responsible for Devon Miller, a 26-year-old patient with levamisole induced lung injury.  Pulmonary dead-space fraction has been associated with increased risk of death in patients with Acute Respiratory Distress Syndrome.

Define dead space fraction (1 mark)

Provide the normal dead-space fraction in a non-intubated patient as a ratio of dead space volume to tidal volume (1 mark)

Describe the factor or structure with greatest contribution to dead space in non-intubated people with normal lungs (1 mark)

Everlyn Mendoza is a 41-year-old woman is brought to the emergency department after being found unconscious in an industrial warehouse fire. She was exposed to heavy smoke in an enclosed space for approximately 20 minutes. On arrival, she is confused and agitated. Vitals: HR 118 bpm, BP 128/72 mmHg, RR 26, SpO₂ 100% on non-rebreather mask. She is intubated for airway protection and placed on volume control ventilation: Vt 480 mL, RR 20, PEEP 8, FiO₂ 1.0. Plateau pressure 20 cmH₂O.

Investigations: ABG: pH 7.19, PaCO₂ 32 mmHg, PaO₂ 410 mmHg. Hemoglobin: 110 g/L. Lactate 13

Identify two distinct mechanisms of impaired oxygen delivery or utilization present in this patient (2 marks).

List two SPECIFIC ANTIDOTES for Everlyn (2 marks)

List two reasons why conventional oxygenation measurements may be inaccurate in this case (2 marks)

Giulia Roselli is a 24-year-old female with medical history of Hashimoto thyroiditis in remission without medications, severe asthma with FEV1/FVC of 0.6 and obesity treated with GLP-1 agonist. Compliance with inhaled bronchodilators is poor. Prior to admission her dietary intake was poor secondary to nausea and vomiting from her GLP1 agonist. She presented with status asthmaticus and was intubated for mixed hypoxemic and hypercarbic respiratory failure. Current vitals: HR 110bpm arterial BP 80/40 (MAP 53mm Hg) T 37.0. Ventilator settings: VCV Vt 250mL PEEP 10cm H2O R 20 FiO2 0.3 SpO2 75%. Endotracheal suctioning reveals thick secretions requiring saline for mobilization. She is emaciated.

Chest x-ray is shown below

ABG: 7.27/PCO2 60mm Hg/PO2 60/HCO3 28 BE 0 Lac 4mmol/L SpO2 90%

List TWO etiologies to explain discordance between plethysmography and arterial blood gas (2 marks). Assume the probe is correctly placed, there is no motion artefact and the waveform is good.

Calculate the alveolar partial pressure of oxygen (2 marks)

The value you calculate above is inaccurate. Explain which assumption for calculating the PAO2 is violated in the case of Giulia and why (2 marks)

Describe the impact of the arterial blood gas result on oxyhemoglobin binding (1 mark)

Markus Vappen is a 66-year-old male admitted to ICU for invasive mechanical ventilation for respiratory failure from Escherichia coli bacteremia and pneumonia.  He is heavily sedated, and unresponsive to stimulation.  The RT calls you to reassess because the respiratory rate is now > 50/minute.  Blood gases show pO2 on 30% O2 146, PCO2 9 pH 7.64.  Ventilator waveforms are shown below.

Describe your differential diagnosis and next steps (3 marks)

Arian Lindsay is a 24-year-old female with respiratory failure in the context of suspected APML.  A large anechoic structure is noted on thoracic point of care ultrasound.  Describe the method for estimation of pleural fluid volume using thoracic point of care ultrasonography (2 marks)

Shelly McIsaac is a 56-year-old patient ventilated with pressure control ventilation at the following settings: RR 22 PC 20 PEEP 12 with inspiratory time 0.8 sec.

Provide the peak airway pressure (1 mark)

Provide the driving pressure, if possible.  If not possible, explain why this is the case (2 marks)

The Registered Respiratory Therapist recommended increasing inspiratory time as mechanism to increase tidal volume.  Explain whether this will succeed.  Provide two other factors influencing tidal volume in a pressure-controlled mode (3 marks)

Describe the time constant and provide formulae for one time constant (2 marks)

Lucius Vernon is a 60-year-old gentleman receiving invasive mechanical ventilation for 8 days in the intensive care unit.  Bedside staff alert you to ventilator asynchronies.

Name the dyssynchrony, identify one disease state (acute or chronic) this dyssynchrony might be expected and the most appropriate ventilator setting modification to address it (3 marks)

Pressure time graph is shown below for Jasmine Kennedie.

Describe the ventilator maneuver used during the second breath, identify the MODE of ventilation used during this breath and provide an example of how information derived from this maneuver influences management (4 marks)

For the third breath, explain this ventilator maneuver, what this maneuver demonstrates for this patient and propose TWO strategies to mitigate the issue (4 marks)

Max Prime is a 40-year-old gentleman experiencing ventilator dyssynchrony in your intensive care unit.  Flow, pressure and esophageal pressure (pmus) are shown below.

Identify the dyssynchrony, describe your approach to modifying the ventilator parameters to rectify the situation and provide one example of a disease state (acute or chronic) where this might be seen (3 marks)

Clarence Marshall is a 77-year-old male admitted to intensive care unit with hypoxemic respiratory failure.  Symptoms developed three days prior with fever, cough without sputum and dyspnea.  Medical history is significant for hypertension and diabetes controlled on telmisartan and dapagliflozin.

List the criteria for diagnosis of ARDS according to the Berlin Definition (4 marks)

Xala Lohmes is a 40-year-old female who receives veno-venous extracorporeal membrane oxygenation for refractory hypoxemia in the context of coronavirus-19 pneumonia and acute respiratory distress syndrome.  The surgeon involved with cannulation seeks a discussion around optimal circuit configuration.

DECRIBE the cannulation strategy for dual-lumen cannula (e.g. Avalon) and two site in terms of drainage and return cannulas (4 marks). For two-site, describe the MOST COMMON strategy.

The patient is initiated successful on ECMO.  Settings for ECMO are: Flow 3.5LPM sweep 4LPM FiO₂ 0.8 RPM 2800 Temp 36.5.  Ventilator settings are Assist-Control Volume Controlled Ventilation frequency 10 breaths/minute VC 350mL PEEP 10 FiO₂ 0.4. List three factors influencing oxygenation for patients on VV-ECMO. (3 marks)

Identify the ECMO setting or parameter with greatest impact on arterial pCO₂ (1 mark)

Lorraine Welkie is a 45-year-old female admitted with hypothermia undergoing re-warming. Her ventilator pressure and esophageal pressure tracings are shown below.

Identify the dyssynchrony (1 mark)

Provide ONE etiology for this dyssynchrony in the context of this patient (1 mark)

Describe TWO mechanisms of rectifying the dyssynchrony (2 marks)

Avery Hamilton is a 48-year-old female under your care with severe ARDS on V-V ECMO with an oxygen blender/centrifugal pump and a Quadrox® membrane oxygenator.  Flow rate is 6L/min. with the extracorporeal oxygen fraction 0.55.  The patient is intubated and ventilated with a tidal volume of 4mL/kg Predicted Body Weight, rate 20 and driving pressure of 10 cmH₂O.  Oxygen saturation is 89%.  pCO₂ is 78 with a pH of 7.16.  The perfusionist asks for advice in decreasing the pCO₂.

Provide your recommendation with justification (2 marks)

Dwayne Brown is a 50-year-old male admitted to ICU with hypoxemic respiratory failure and acute respiratory distress syndrome from pneumococcal pneumonia.  You assess him two days after admission.  Ventilator settings are:  AC-Volume Control. VC 325mL frequency 28 breaths/minute FiO₂ 0.9 PEEP 18cm H₂O.

List three management strategies for severe ARDS (3 marks)

Explain the rationale for neuromuscular blockade in this patient (1 mark)

Investigations reveal creatinine of 250. Provide two agents you would consider for neuromuscular blockade and identify their important difference (3 marks)

Identify the class of medication to which cisatracurium belongs (1 mark)

Describe the mechanism of action of cisatracurium (1 mark)

Kristin Villa is a 43-year-old female admitted with hypoxemic respiratory failure from smoke inhalation.  She was extricated from a house fire.  Despite twenty-four hours of lung protective ventilation and judicious volume administration she remains hypoxemic with the following ventilator settings:  Volume controlled ventilation assist control, Vt 425mL Frequency 28bpm PEEP 14cm H2O.

List four mechanisms for increasing oxygenation with proning (4 marks)

List two potential adverse effects from prone position ventilation (2 marks)

Jebediah Shelby is a 63-year-old male admitted to the intensive care unit following cardiac arrest.  Brain death has been diagnosed.  Bronchoscopy is undertaken for donation consideration.  Review the following bronchoscopic images

Identify the anatomic variant in the photograph below (1 mark)

Identify the anatomic structure indicated by the yellow circle (1 mark)

Nathan Franks is a 55-year-old male admitted to intensive care for acute respiratory distress syndrome from septic shock in the context of infective pancreatic necrosis.  Dual mode ventilation is ordered.  PEEP 10cm H₂O.  The tracing below depicts thirty seconds of ventilator waveform information.

Identify the two breath types (2 marks)

Label the ventilator asynchrony indicated by arrow A (1 mark)

Outline two modifications to the ventilator settings to improve synchrony (2 marks)

Damian Leonard is a patient admitted to the intensive care unit under your service.  He is intubated, ventilated and has sedation and neuromuscular blockade.  Gases (arterial) show a pCO₂ of 62 mmHg and pH of 7.23.  Minute ventilation is 4 L/min with Vt 300mL on the following settings:  APRV P_high 20cm H₂O P_low 10cm H₂O rate 6 t_high 4.5s t_low 0.8s

Without changing modes, list two ventilator modifications to decrease pCO₂ (2 marks)

Provide the equation for pCO₂ (2 marks)

Describe two mechanisms that account for the pCO₂ deviation (2 marks)

List four phases of the ventilatory cycle (3 marks)

Kendrah Albert is a 30-year-old female admitted to critical care following exploratory laparotomy, four quadrant packing and missile extraction following penetrating traumatic injury from gun shot wound.  She received 12L of crystalloid and blood products during the resuscitation. You are analyzing the ventilator.  Provide equations for the following respiratory measurements (6 marks)

Dynamic compliance
Static compliance
Resistance
Driving pressure
Time constant
Equation of motion

Patrease Collins is a 48-year-old female in your ICU with COPD. She was admitted 3 days ago with an acute exacerbation and are now weaning the ventilator in pressure support ventilation (PEEP 5 cm H₂O, Pressure Support 10 cm H₂O, FIO₂ 0.3 Expiratory Trigger Sensitivity 25% Respiratory Rate 28). Work of breathing is increased. Ventilator waveforms are displayed below.

Describe the ventilator dyssynchrony (1 mark)

Assuming sensitivities are set appropriately, provide the most likely etiology for the dyssynchrony (1 mark)

Outline one management step to mitigate the most likely etiology (1 mark)

Xavier Rodgers is a 60-year-old male receiving non-invasive ventilation using a bilevel ventilator with oro-nasal mask interface. The circuit has a passive exhalation valve, bacterial and viral filter, and anti-asphyxia valve within the mask. The ventilator interface is displayed below.

Identify the delta pressure (1 mark)

The tidal volume drops suddenly from 700mL to 400mL.

Identify the most likely cause for this volume change (1 mark)

Describe how carbon dioxide rebreathing is prevented in a SINGLE-limb circuit and DUAL-limb circuit (2 marks)

Betsy Garner is a 74-year-old female who developed hypoxemic respiratory failure after receiving two units of packed red blood cells.  She is post-operative day two from low anterior resection for colorectal cancer.  On examination blood pressure is 160/85, heart rate is 100bpm in sinus rhythm, respiratory rate is 25 and SpO­₂ on room air is 80%. Point of care ultrasound reveals diffuse B-line pattern with lung sliding present. Respiratory Therapy suggests initiation of non-invasive bilevel positive airway pressure ventilation.

List two physiologic benefits to the respiratory system afforded by positive intrathoracic pressure (2 marks)

Describe the effect of positive pressure ventilation and positive end expiratory pressure on the left ventricular afterload (2 marks)

Provide the equation for the Law of La Place including variables that impact afterload (1 mark)

Dennis Gunderson is a 44-year-old male admitted to the intensive care unit for invasive mechanical ventilation.  He developed acute cor pulmonale from acute respiratory distress syndrome. Pulmonary artery and esophageal manometry probes were inserted to guide his resuscitation.

Provide equations for the following physiologic parameters (6 marks)

Driving Pressure
Lung Stress
Lung Strain
Equation of Motion
Work of Breathing,
Fick Equation

Miley Gil is a 37-year-old female admitted with status asthmaticus to the critical care unit.  Provide the cycle variable in the three modes of ventilation listed below:

Pressure-control, Volume ventilation, Pressure-support (3 marks)

Define cycling (1 mark)

Melissa Loraine is a 41-year-old female admitted with bupropion intoxication.  She is treated with invasive ventilation.  The tracing below depicts 30 seconds of ventilator waveform information from a patient receiving mechanical ventilation.

Indicate the breath type at arrow A (1 mark)

Identify the ventilation mode used over this thirty second period (1 mark)

Simon Nipho is a 68-year-old man with cirrhosis (Child-Pugh B, MELD 22) intubated for 5 days following variceal hemorrhage requiring urgent endoscopy; he is now hemodynamically stable, FiO2 0.35, SpO2 96%, and passes a 30-minute SBT with PSV 8 cmH2O; GCS is 10 (E3V2M5); he does not cough spontaneously; vigorous tracheal suctioning reliably elicits a strong cough; secretions are moderate in volume, thick, and require suctioning every 90 minutes; ETT is 6.0 mm ID; with the cuff deflated, exhaled VT changes from 540 mL to 535 mL.

a) List two airway protection findings predicting extubation failure in this patient despite passing the SBT. (2 marks)

b) State the clinical significance of an absent cuff leak result in this patient given the 6.0 mm ETT. (1 mark)

Cheryl Mitch is a patient with sepsis is ventilated in dual mode using intermittent mandatory ventilation (IMV) with volume control, flow-targeted breaths (mandatory), and pressure support breaths (spontaneous). The tracing below depicts 30 seconds of ventilator waveform information.

Indicate the breath (A or B) representing a volume control, flow-targeted breath (1 mark)

Identify the type of asynchrony at denoted by breath A (1 mark)

Provide one modification for the asynchrony at breath A (1 mark)

Nina Sawyer is a 75-year-old woman with chronic obstructive lung disease and dialysis-dependent renal failure is admitted to the ICU with pneumonia and pulmonary edema.  She requires intubation with a #7.0 ETT, sedation, paralysis and is mechanically ventilated in the volume-targeted assist-control mode.

Calculate the dynamic compliance of the respiratory system for this patient.  Show the equation you are using and your calculations (2 marks)

Calculate the static compliance of the respiratory system for this patient.  Show the equation you are using and your calculations (2 marks)

Two hours later, the patient remains sedated and is not triggering the ventilator.  Peak airway pressure has now increased to 50 cm H₂0 yet both end-inspiratory and end-expiratory occlusion pressures have remained unchanged.  Provide ONE reason for the increased peak airway pressure in this situation.  Justify your answer. (3 marks)

The flow pattern is changed to square wave with flow 50 L/min.  Predict the effect (assuming no other changes in ventilator setting) on: (3 marks)

Tidal volume, End inspiratory occlusion pressure, Inspiratory time

Given a square wave flow pattern with flow 50 L/min and information from the table,  calculate respiratory resistance.  Show the equation that you are using (2 marks)

Margaret Debora is a 51-year-old female admitted with hemorrhagic shock secondary to perforated peptic ulcer disease.  Extubation is under consideration.  One of the criteria for a spontaneous breathing trial is the f/V_T ratio.

Describe the significance of this ratio and provide one generally accepted criterion to predict successful weaning (2 marks)

Name one population in whom RSBI does not predict weaning success well (1 mark)

Roger Geddes is a 50-year-old male who experienced a traumatic spinal cord injury from a fall.

Describe the neurological physical examination findings for a patient with spinal cord injury at C5-6 (3 marks)

Explain whether the patient will be more comfortable breathing supine or upright with justification (2 marks)

Mr. Fernandez is weaning through invasive mechanical ventilation with a #7 Bivona tracheostomy in situ.  He was admitted to ICU for hypoxemic respiratory failure secondary to streptococcal pneumonia.  Relevant medications include dexamethasone and cisatracurium for treatment of acute respiratory distress syndrome 15 days ago.  During RRT morning assessment for suitability to undergo tracheal mask trial p0.1 was measured as +4.0 with Mr. Fernandez receiving the following settings: PSV PS 16cm H₂O PEEP 8cm H₂O FiO₂ 0.25 trigger 2cm H₂O cycle expiratory time sensitivity 35%.

Describe the method of p0.1 measurement (1 mark)

Provide normal ranges for p0.1 (2 marks)

Describe the implication of p0.1 exceeding the upper limit of normal (1 mark)

Based upon Mr Fernandez p0.1, explain whether you would advocate proceeding with trach mask trial or continuing positive pressure ventilation (1 mark)

Barnaby Richard is a 68-year-old male admitted with septic shock from ascending cholangitis.  After three days of volume resuscitation and vasopressor use, his blood pressure remains labile prompting thoracic point of care ultrasound.  Compare and contrast A and B line patterns in thoracic ultrasound (8 marks)

James Booth is a 58-year-old male patient extubated 2 hours ago after passing SBT. He was intubated in the Operating Room yesterday for total knee replacement and remained intubated due to prolonged sedation effects. Cuff leak test was 10 mL (1%). Patient now develops inspiratory stridor audible at bedside, respiratory rate 28, SpO2 91% on FiO2 0.40 by facemask, using accessory muscles. The patient is anxious but follows commands with no voice change.

a) Identify which intervention should be attempted first before reintubation and explain the physiologic rationale. (2 marks)

b) List two clinical findings that would indicate this therapy has failed and reintubation is required. (2 mark)

c) List TWO risk factors for post-extubation stridor. (2 marks)

d) State whether you would have performed a cuff leak test for Mr. Booth with YES or NO. (1 mark)

e) Identify which statistical characteristic of cuff leak testing for prediction of post-extubation stridor is higher. Write SENSITIVITY or SPECIFICITY (1 mark)

Anansi Blay is a 54-year-old male admitted to the intensive care unit with hypoxemic respiratory failure secondary to transfusion related acute lung injury.  Ventilator settings are: AC-PC PC 22cm H2O PEEP 12cm H2O, FiO2 0.6 Ti 0.8 frequency 24bpm trigger 3LPM ramp 50ms. Vt is 330mL VE 7.9LPM. ABG shows pH 7.10 pCO2 79mm Hg. Without increasing pressure control, describe modifications or maneuvers to increase ventilation

THREE ventilator modifications  (3 marks)

TWO non-ventilator maneuvers (2marks)

You are caring for Salman Mourad, a 45-year old male with cardiac amyloidosis, congestive heart failure with depressed ejection fraction, pulmonary hypertension on the basis of cardiomyopathy. He is intubated in your ICU for ST elevation myocardial infarction post PCI with subsequent development of hypoxemic respiratory failure on the basis of atelectasis, cardiogenic pulmonary edema and worsened pulmonary hypertension. A light sedation strategy is implemented with RASS +1 on dexmedetomidine 0.3mcg/kg/m. Vitals are as follows: BP 180/110mm Hg HR 110bpm RR 20 SpO2 88% T 36.5. Ventilator settings are: PSV PS 14cm H2O PEEP 10cm H2O FiO2 0.5

a) Inhaled nitric oxide is initiated. Describe ONE indication for inhaled nitric oxide and describe the SINGLE MOST LIKELY vital sign impact (2 marks)

b) Describe the MOST IMPORTANT ALARM providing notification of circuit disconnect in the inhaled nitric oxide (1 mark)

c) Nitroglycerine intravenous infusion is initiated for hypertension and pulmonary edema. Aside from a decrease in blood pressure, describe the SINGLE MOST LIKELY physiologic impact (1 mark)

d) The patient passes a spontaneous breathing trial on the abovementioned settings and inhaled nitric oxide. Immediately post extubation the oxygen saturation is 70% with an FiO2 of 1.0. Aside from atelectasis, LIST ONLY TWO LIKELY ETIOLOGIES for severe hypoxemia in this circumstance (2 marks)

Ramon Gaos is a 24-year-old man with severe asthma is paralyzed and intubated in the ED. Ventilator settings: assist control, RR 16, VT 700 mL, FiO2 100%, PEEP 5 cmH2O. ABG 20 minutes later: pH 7.24, PaCO2 53, PaO2 242, HCO3 23. Peak pressure is 48 cmH2O. The respiratory therapist proposes increasing VT to 800 mL and RR to 20.

a) Describe the effect of increasing VT on peak pressure. (1 mark)

b) Define autoPEEP and describe the effect of increasing RR on autoPEEP in this patient. (1 mark)

c) Describe how you would distinguish airway versus lung parenchymal causes of elevated peak pressure. (1 mark)

d) List FOUR ventilator adjustments to reduce autoPEEP. (2 marks)

Nick O’Donnell is a 23-year-old man presenting to the ED with an acute severe asthma exacerbation. Despite maximal medical therapy including inhaled bronchodilators, systemic corticosteroids, and magnesium sulfate, he continues to deteriorate. The team is deciding whether intubation is required.

a) List FOUR clinical indicators that should prompt intubation in a patient with acute severe asthma. (4 marks)

Leta Jonatan is a 62-year-old woman (ideal body weight 65 kg) with bilateral pneumonia and streptococcal bacteremia who is intubated and mechanically ventilated overnight.

Morning ventilator settings: assist control, RR 18, VT 700 mL, FiO2 50%, PEEP 10 cmH2O. ABG: pH 7.43, PaCO2 38, PaO2 74, HCO3 21. Peak pressure 42 cmH2O, plateau pressure 38 cmH2O.

a) Describe the ventilator changes you would make and the rationale for the most important change. (2 marks)

George Rhodopis is a 52-year-old man with severe ARDS (PaO2/FiO2 110) on lung-protective ventilation with FiO2 0.7 and PEEP 14 cmH2O who is being considered for prone positioning. He has been intubated and ventilated for 18 hours.

a) List THREE physiologic mechanisms by which prone positioning reduces hypoxemic respiratory failure. (3 marks)

b) Arterial blood gas drawn one hour after proning reveals P/F of 100. Outline your management in RESPONSE to this PF. (1 mark)

A 38-year-old man named Rob Wagner is mechanically ventilated for pancreatitis-induced ARDS. On day 5, you identify subcutaneous air in the neck and a pericardial rub on examination. Chest X-ray confirms pneumopericardium, pneumomediastinum, and subcutaneous emphysema of the neck. The patient is hemodynamically stable and his clinical status is unchanged.

a) Describe your management of pneumopericardium, pneumomediastinum, and subcutaneous emphysema in this ventilated patient. (1 mark)

Gerald Jacob is a 55-year-old obese hypertensive man who presents to the ED with daytime somnolence. ABG on room air: pH 7.33, PaCO2 64, PaO2 40, HCO3 33, Hgb 190 g/L, barometric pressure 760 mmHg.

a) Describe the acid-base status. (1 mark)

b) Calculate the PaO2/FiO2 ratio. (1 mark)

c) State the most likely diagnosis. (1 mark)

Four 60 kg women from the Villages Community are intubated and placed on assist-control volume-controlled ventilation. Match each patient to the most appropriate setting:

1) 40-year-old with ARDS from alcoholic pancreatitis
2) 21-year-old with severe DKA and urosepsis, normal CXR, pH 6.92, PaCO2 12, PaO2 110 on room air pre-intubation.
3) 68-year-old with COPD exacerbation from lobar pneumonia.
4) 56-year-old with bullous emphysema post-wedge resection with large air leak and chest tube.

Available settings:
A) VT 550 mL, RR 14, FiO2 35%, PEEP 0;
B) VT 550 mL, RR 28, FiO2 28%, PEEP 0;
C) VT 550 mL, RR 14, FiO2 35%, PEEP 5;
D) VT 360 mL, RR 32, FiO2 50%, PEEP 10.

(4 marks)

A 35-year-old woman from Guatemala named Jenny Aranza 20 weeks pregnant, presents with right shoulder discomfort, fever, and fatigue. Vital signs: RR 32, SpO2 89%, HR 124, BP 90/60. Examination reveals stony dullness and decreased breath sounds at the right lower zone. CXR shows a right pleural effusion. She has no significant exposures.

a) Provide THREE possible diagnoses. (3 marks)

b) State THREE criteria that distinguish an exudate from a transudate by Light’s criteria. (3 marks)

c) Provide FOUR diagnoses that cause bloody pleural effusions. (4 marks)

A 62-year-old intubated man named Emir Amadis develops a rising peak airway pressure with an unchanged plateau pressure on morning rounds. Dynamic compliance has decreased from baseline.

a) List THREE causes of decreased dynamic compliance. (3 marks)

Zorba Mair is a 42-year-old female with massive upper gastrointestinal bleeding from peptic ulcer disease. She is intubated with a 7.5 evacuation endotracheal tube and undergoing invasive ventilation with a Hamilton G5 ventilator. Provide the corresponding number to the following ventilator components. If the component listed does not exist on the Hamilton G5 ventilator configuration shown, write in “Not Shown”.

A. Inspiratory Limb
B. Humidity Moisture Exchanger
C. Expiratory Limb
D. Heater Humidifier
E. Antibacterial Filter

A 55-year-old woman, Andrada Cornelia, is mechanically ventilated for pneumonia develops rising plateau pressures over 48 hours. Peak and plateau pressures have risen proportionally. The team suspects decreased static compliance.

a) List THREE causes of decreased static compliance. (3 marks)

A 48-year-old male named Brett McGarry with ARDS is mechanically ventilated in volume-control mode. The team is performing a respiratory mechanics assessment to track disease progression.

a) Define static compliance and state the formula used to calculate it. (2 marks)

a) Define dynamic compliance and state the formula used to calculate it. (2 mark)

Roco Maija is a 27-year-old man admitted to the neurology ward with Guillain-Barré syndrome who is referred to the ICU for respiratory assessment with ascending weakness now involving his proximal upper limbs. The team is monitoring his respiratory function and reviewing the neuromuscular conditions.

a) State the normal vital capacity in healthy adults in mL/kg. (1 mark)

b) State the vital capacity threshold in mL/kg at which impending respiratory muscle failure should be suspected. (1 mark)

c) State how vital capacity is measured as a monitoring parameter at the bedside. (1 mark)

d) Briefly contrast the pathophysiology of Guillain-Barré syndrome versus Myasthenia Gravis and identify ONE precipitant of Guillain-Barré syndrome. (3 marks)

Ilshat Ziya is a 52-year-old man with severe ARDS who is mechanically ventilated in the ICU. The team is reviewing mechanisms of ventilator-induced lung injury and the monitoring parameters used to detect complications.

a) Define barotrauma. (1 mark)

b) List FOUR monitoring parameters for complications of barotrauma. (4 marks)

c) Define volutrauma. (1 mark)

d) Define biotrauma. (1 mark)

Vasilia Herse is a 44-year-old woman with moderate ARDS from pneumonia being mechanically ventilated. The team is implementing a lung-protective ventilation strategy to minimize ventilator-induced lung injury.

a) List FIVE components of lung-protective ventilation. (5 marks)

A 58-year-old man, Darius Alcione, with ARDS on mechanical ventilation has persistent hypoxemia despite optimized PEEP. The intensivist proposes a recruitment maneuver before further adjustment of ventilator settings.

a) Define lung recruitment in the context of mechanical ventilation. (1 mark)

Stacey Peto is a 47-year-old woman with severe ARDS who has persistent refractory hypoxemia. The team decides to perform a sustained inflation recruitment maneuver. The bedside nurse asks about the potential harms of this intervention.

a) List THREE potential complications of a recruitment maneuver in the mechanically ventilated patient. (3 marks)

Jose Hobbs, a respiratory therapist, asks you to explain the concept of PEEP to a new ICU trainee during morning rounds.

a) Define PEEP. (1 mark)

Shant Aram is a 61-year-old man with ARDS being mechanically ventilated with a PEEP of 10 cmH2O. The team is reviewing the physiologic rationale for applied PEEP during morning rounds.

a) List THREE goals of applied PEEP in the mechanically ventilated patient. (3 marks)

Dennis Lindon is a 73-year-old man with ARDS is mechanically ventilated on PEEP 14 cmH2O. He develops hypotension and his triggering effort appears ineffective on the flow-time waveform. The team is reviewing the potential adverse consequences of applied PEEP.

a) List THREE potential consequences of applied PEEP in the mechanically ventilated patient. (3 marks)

Manny Devine is a 50-year-old male treated in your intensive care unit with hypoxemia in the context of pulmonary emboli.  He is maintaining a saturation of 89% on FiO2 0.8 Q60LPM via high flow nasal cannula oxygen.

Manny Devine is a 50-year-old male treated in your intensive care unit with hypoxemia in the context of pulmonary emboli.  He is maintaining a saturation of 89% on FiO2 0.8 Q60LPM via high flow nasal cannula oxygen.

Describe the typical blood gases in a spontaneously breathing patient with a small-moderate sized pulmonary embolism. (pO₂ , pCO₂ and pH) (1 mark)

Assuming a patient is intubated and ventilated, under heavy sedation, with no triggering of the ventilator. State the impact of a pulmonary embolism on the end-tidal CO₂ and IDENTIFY the reason (2 marks)

Describe FOUR physiological mechanisms causing hypoxemia in patients with pulmonary embolism (4 marks)

A 67-year-old man named Jorge Armide with severe COPD is mechanically ventilated for an acute exacerbation with high peak and plateau pressures. The team is discussing his risk for barotrauma and pneumothorax.

a) List TWO risk factors for developing a non-traumatic pneumothorax in the mechanically ventilated patient. (2 marks)

Carla Forest is a 66-year-old woman who is being assessed for extubation readiness after being mechanically ventilated for six days following ARDS. A spontaneous breathing trial on Pressure Support Ventilation PS 5cm H2O PEEP 5cm H2O Fi02 0.3 is initiated.

a) List the objective criteria used to define a SUCCESSFUL spontaneous breathing trial. (3 marks)

b) Define the RSBI, state its formula, and describe the thresholds used to predict weaning success or failure. (4 marks)

Sunita Krishnamurthy is a 61-year-old woman with severe bronchospasm on mechanical ventilation with the same settings as the prior case: pressure-control ventilation, rate 24, inspiratory time 0.8 seconds, static compliance 20.2 mL/cmH2O, airway resistance 46 cmH2O/L/s, time constant 0.93 seconds, and expiratory time 1.70 seconds. Her dynamic compliance is calculated from volume-control data: peak pressure 48 cmH2O, plateau 25 cmH2O, PEEP 10 cmH2O, tidal volume 344 mL.

a) Calculate dynamic compliance from the volume-control data provided. (2 marks)

b) Name the component of the equation of motion responsible for this discrepancy. (1 mark)

c) List TWO ventilator setting changes that would increase the number of time constants available for exhalation at the current respiratory rate, and state ONE clinical risk of each change. (2 marks)

Ralph Brock is a 52-year-old man who develops a large left pleural effusion following esophagectomy. Thoracentesis is performed and the fluid appears milky white. The team is applying laboratory criteria to confirm the diagnosis of chylothorax.

a) List the THREE laboratory criteria used to diagnose chylothorax. (3 marks)

Rudolph Klimp is a 42-year-old man is admitted to the ICU with bilateral pulmonary infiltrates, PaO2/FiO2 ratio of 140 mmHg, and no clinical evidence of infection or primary pulmonary pathology. The team is reviewing non-pulmonary and non-infectious causes of ARDS.

a) List SIX non-pulmonary, non-infectious causes of ARDS. (6 marks)

Beatriz Carvalho is a 58-year-old woman with severe ARDS on mechanical ventilation. In volume-control mode with a square flow waveform, flow is set at 30 L/min, peak airway pressure is 48 cmH2O, plateau pressure is 25 cmH2O, and PEEP is 10 cmH2O. In pressure-control mode, an inspiratory hold maneuver yields a tidal volume of 344 mL, plateau pressure 27 cmH2O, and PEEP 10 cmH2O.

a) State how static compliance is measured at the bedside (ventilation modality, maneuvre, patient condition) (3 marks)

b) Name the two measurements required to calculate static compliance (2 marks)

c) Calculate the static compliance from the data provided. (1 mark)

b) Name the measurements required for airway resistance, and calculate resistance from the data provided. (3 marks)

Femi Adeyemi is a 52-year-old man with obstructive lung disease on pressure-control ventilation: pressure control 25 cmH2O above PEEP, PEEP 10 cmH2O, respiratory rate 24 breaths/min, inspiratory time 0.8 seconds, FiO2 0.5. An inspiratory hold yields tidal volume 344 mL and plateau pressure 27 cmH2O. In volume-control with square flow at 30 L/min, peak pressure is 48 cmH2O and plateau is 25 cmH2O. Using the static compliance and resistance calculated from these values, answer the following.

a) State the formula for the time constant and calculate its value using the data provided. (3 marks)

b) Calculate the expiratory time available at the current settings and calculate the number of time constants completed during expiration. (2 marks)

c) State the minimum number of time constants required for near-complete exhalation and classify this patient’s exhalation as complete or incomplete. (1 mark)

Tariq Nasrallah is a 44-year-old man with a known small right-sided pneumothorax and pre-existing bilateral lower lobe atelectasis. He is breathing spontaneously and haemodynamically stable. The team applies 100% oxygen via non-rebreather mask with the intention of accelerating pneumothorax resorption. After application SpO2 decreases by 2%.

a) State the gas displaced by administration of 100% oxygen that accelerates pneumothorax resorption (1 mark)

b) In TWO WORDS state the physiologic principle explaining how oxygenation can DECREASE with administration of 100% oxygen (1 mark)

c) State whether the physiologic principle referenced in part b) above is more likely in a low V/Q alveolus or high V/Q alveolus (1 mark)

A 28-year-old woman named Hannah Grouse presents at 28 weeks gestation with a previously uncomplicated pregnancy presents with two days of hemoptysis and pleuritic chest pain. She has no personal or family history of thromboembolism, no signs of DVT, a normal chest X-ray, and a D-dimer of 200 ng/mL.

a) State the ONE investigation or management strategy you would pursue next. (1 mark)

Archie Morraine is a 55-year-old man with severe ARDS from aspiration pneumonitis on volume-control ventilation; settings: VT 480 mL (6 mL/kg PBW 80 kg), RR 24, PEEP 24 cmH2O, FiO2 0.75, SpO2 91%; plateau pressure on inspiratory hold is 38 cmH2O; esophageal pressure at end-expiration is +6 cmH2O and at end-inspiration is +12 cmH2O.

a) Calculate the driving pressure. (1 mark)

b) Calculate the end-expiratory transpulmonary pressure. (1 mark)

c) State ONE ventilator change you would make to address the end-expiratory transpulmonary pressure (1 mark)

c) State whether the driving pressure exceeds the threshold associated with increased ARDS mortality. (1 mark)

d) List two ventilator adjustments that would reduce driving pressure, and state the physiologic trade-off of each. (2 marks)

Lamar Hough is a 35-year-old patient with blunt thoracic injury from a belted motor vehicle collision.  List three pathologic ultrasound findings that may be seen with a pneumothorax (3 marks)

Beatriz Carvalho is a 57-year-old woman who developed severe ARDS from aspiration pneumonitis 72 hours after triple-vessel CABG via median sternotomy; she is on volume-control ventilation with VT 6 mL/kg PBW, PEEP 12 cmH2O, FiO2 0.80, PaO2/FiO2 88 mmHg despite neuromuscular blockade; the sternal wound is closed, dry, and intact with intact skin sutures but the cardiac surgery team advises against sustained anterior thoracic pressure; temporary epicardial pacing wires exit through the inferior sternal incision.

a) List two PROSEVA eligibility criteria met in this patient. (2 marks)

b) State the primary mechanical contraindication to standard prone positioning in this patient. (1 mark)

c) State one prone positioning modification that may reduce anterior wound pressure while permitting prone sessions. (1 mark)

d) State one rescue strategy for refractory hypoxemia if prone positioning cannot be safely sustained for 16 consecutive hours. (1 mark)

Tenzin Dorjee is a 71-year-old man with severe COPD (FEV1 28% predicted) presenting with acute hypercapnic respiratory failure: pH 7.28, PaCO2 72 mmHg, PaO2 58 mmHg on 2L O2, RR 34, accessory muscle use, GCS 14. BiPAP is initiated at IPAP 12 / EPAP 5 cmH2O. After 20 minutes he is agitated, fighting the mask, and not triggering reliably — the RT states the patient should be intubated for agitation. Current settings show a trigger sensitivity set to -3 cmH2O, rise time 400 ms, inspiratory time 1.1s, fall time 200ms. SpO2 is 88%, RR 38.

a) State the primary indication for NIV in this patient and identify the pH threshold below which NIV is strongly recommended over standard oxygen therapy in hypercapnic respiratory failure. (2 marks)

b) State the two ventilator settings responsible for the dyssynchrony and name the corrective adjustment for each. (2 marks)

c) State two sedative or analgesic agents appropriate for use to improve NIV tolerance in this agitated patient (2 marks)

d) State two criteria indicating NIV has failed and intubation is now required. (2 marks)

Luisa Cavalcanti is a 48-year-old woman with bilateral pneumonia and hypoxemic respiratory failure. SpO2 88% on 15L non-rebreather, RR 36, she is placed on HFNC at 50 L/min, FiO2 0.60. At one hour SpO2 is 94%, RR 28. The team asks about the physiologic benefits of HFNC and how to know when to escalate to intubation.

a) List TWO physiologic mechanisms by which HFNC improves oxygenation and reduces work of breathing compared to standard oxygen. (2 marks)

b) Calculate the ROX index at one hour and state the threshold below which intubation risk is high. (2 marks)

c) State two clinical findings — other than ROX index — that indicate HFNC is failing and intubation should not be delayed. (2 marks)

Mikhail Petrenko is a 67-year-old man with severe COPD presenting with acute hypercapnic exacerbation: pH 7.30, PaCO2 68 mmHg, RR 32. CXR shows a small right-sided pneumothorax measuring 0.9cm with no mediastinal shift and no tension features. He has no IV access and is in a community hospital with no thoracic surgery on site and an Emergency Physician uncomfortable with chest tube insertion. The team debates whether to start NIV given the pneumothorax.

a) State whether NIV is absolutely contraindicated in the presence of a small pneumothorax and identify the clinical and radiographic precondition that must be met before proceeding. (2 marks)

b) List three findings on BiPAP monitoring data or clinical assessment that indicate the pneumothorax is expanding and NIV must be stopped. (3 marks)

Malcolm Rie is a 51-year-old man with alcohol use disorder, depression, and hypertension transferred to the ICU intubated and on norepinephrine 0.3 mcg/kg/min. His partner found him obtunded with vomitus on his clothes. Vitals: BP 90/55, HR 115, SpO2 90% on FiO2 60%, temperature 38.5°C. Labs: WBC 21, creatinine 150. CXR shows patchy bilateral infiltrates and a moderate left pleural effusion.

a) Provide THREE diagnoses that explain this clinical picture. (3 marks)

b) List THREE diagnostic investigations you would perform. (3 marks)

Mirjam Flanagan is a 64-year-old woman with COPD who required mechanical ventilation for 24 days following severe pneumonia and has had a size 8 cuffed tracheostomy for 18 days.
Phase 1 (Week 4): She has been off invasive mechanical ventilation on tracheostomy mask oxygen, FiO2 0.35, SpO2 94%, suctioning required every 6 hours, haemodynamically stable. Cuff deflation is attempted and tolerated. She passes a finger occlusion test.
Phase 2 (Week 5): She has been downsized to a size 6 cuffed tube.
Phase 3 (Week 6): She is liberated from invasive ventilation. The team debates between a cap with cuff deflated, a speaking valve, and a high-flow tracheostomy adapter.

a) State why downsizing from a size 8 to a size 6 tube before adequate ventilator independence increases work of breathing and identify the physiologic mechanism. (2 marks)

b) State the prerequisite cuff condition for safe speaking valve use and identify the harm of using a speaking valve with the cuff inflated. (2 marks)

c) State the preferred approach for the Phase 3 trial (cap, speaking valve, high-flow) (1 mark)

d) State one criterion used to assess cough adequacy before proceeding to decannulation. (1 mark)

Waneek Nakogee is a 61-year-old woman intubated for hypoxemic respiratory failure secondary to left lower lobe pneumonia with persistent lobar collapse despite antibiotics, undergoing bedside bronchoscopy for mucus plug clearance. During suctioning of a subsegmental bronchus, active but non-massive bleeding obscures the visual field; heart rate is 92/min and SpO2 96% on FiO2 0.6, without hemodynamic instability. Her only regular medication is amlodipine for hypertension.

a) State the single most appropriate immediate maneuver to protect her non-bleeding lung. (1 mark)

b) List three local hemostatic measures administered via the bronchoscope for this bleeding. (3 marks)

c) State the single ventilator adjustment used to tamponade ongoing alveolar bleeding. (1 mark)

d) Despite topical hemostatic measures and increased PEEP, bleeding continues at approximately 50 mL over 10 minutes without desaturation; state the single most appropriate next step. (2 marks)

Ingrid Bjornstad is a 34-year-old woman with no prior medical history who is intubated for 3 days following bilateral community-acquired pneumonia; she is hemodynamically stable, FiO2 0.30, SpO2 98%, GCS 15, strong cough, and minimal secretions; during a 30-minute SBT with PSV 5 cmH2O and PEEP 0: RR 16 breaths/min, VT 450 mL, HR 76 bpm, and the patient appears comfortable; ABG on full assist ventilation earlier that morning: pH 7.44, PaCO2 38 mmHg; ABG at 25 minutes of SBT: pH 7.42, PaCO2 46 mmHg, PaO2 98 mmHg on FiO2 0.30.

a) Calculate the RSBI during the SBT. (1 mark)

b) State whether this RSBI supports proceeding with extubation. (1 mark)

c) Identify the single finding that introduces uncertainty about sustained respiratory adequacy after extubation despite the favorable RSBI and clinical appearance. (1 mark)

d) State one clinical action if this finding continues to worsen by SBT completion. (1 mark)

Tommy Nasmin is a 65-year-old man with Parkinson’s disease (well-controlled on levodopa-carbidopa, independent in ADLs pre-admission, normal SLP swallowing assessment 6 months prior), hypertension, and type 2 diabetes, intubated for 9 days with severe community-acquired pneumonia; each of three daily SBTs has failed at 30-35 minutes with RR increasing from 14 to 34 breaths/min, accessory muscle use, SpO2 dropping from 96% to 91%, and no new crackles; investigations show: LVEF 58%, Grade I diastolic dysfunction with E/e’ ratio 11; BNP 195 pg/mL; diaphragm thickening fraction 22% bilaterally; MIP −26 cmH2O; vital capacity 11 mL/kg PBW; spontaneous minute ventilation on full assist 11.8 L/min.

a) List two physiologic findings best accounting for recurrent SBT failure in this patient. (2 marks)

b) Identify the finding that argues most strongly against a primary cardiogenic etiology of SBT failure. (1 mark)

c) State one non-ventilatory intervention targeting the elevated resting minute ventilation to facilitate weaning. (1 mark)

Adaeze Okonkwo is a 38-year-old woman presenting to a district hospital without arterial blood gas capability, with 4 days of progressive dyspnea, bilateral infiltrates on chest radiograph, no clinical evidence of cardiac failure, and no history of chronic lung disease; she is receiving oxygen via simple face mask at 8 L/min (estimated FiO2 0.44) with SpO2 reading of 99% on pulse oximetry.

a) Calculate the S/F ratio and state the corresponding ARDS severity classification using Rice et al. thresholds. (2 marks)

b) State one limitation of interpreting S/F ratio when SpO2 is ≥ 97%. (1 mark)

c) State one source of FiO2 estimation error when using a simple face mask that affects S/F accuracy in resource-limited settings. (1 mark)

d) State the effect of a large intrapulmonary shunt fraction on the PaO2 response to increasing FiO2. (1 mark)

You are treating Elissa Bradley, a patient with high flow nasal cannula oxygen.  Describe the physiologic effects of HFNC (4 marks)

Ramona Jacobs is a 54-year-old female with enlarged station seven lymph nodes on CT performed for cough and wheeze. Background is significant for twenty pack-year history of cigarette smoke, alcohol misuse disorder and unexplained weight loss of ten kilograms in the past three months. During endoscopic bronchial ultrasound guided biopsy there is massive hemorrhage refractory to local epinephrine injection and endoscopic balloon tamponade. Chest X-ray is shown below. She is intubated for hypoxemia and respiratory distress.

Describe the position of station seven lymph nodes relative to the tracheobronchial tree (1 mark)

Describe THREE techniques for isolating one lung (3 marks)

Franklin Templeton is a 44-year-old male patient admitted to your Critical Care Unit with hypoxemic respiratory failure. Medical history is significant for a question of asthma post covid infection 3 years ago requiring 15 days of invasive mechanical ventilation (no spirometry), GERD and obstructive sleep apnea. Home medications are: atrovent, montelukast, pantoprazole, symbicort, trelegy. Prior to admission to your ICU he was endotracheally intubated, invasively ventilated, initiated on intravenous magnesium sulfate infusion, salbutamol inhaled and IV, ipatropium MDI, ketamine 1.0mg/kg/h IV and epinephrine 5mcg/m. He was weaned from an Anesthestic Delivery Unit two days ago after receiving sevoflurane.

Ventilator settings are as follows: Pressure Control (Assist Control) PEEP 10cm H2O Frequency 24 FiO2 0.5 Ti 0.8s PC 25cm H2O. On these settings Vt 350mL VE 9LPM PIP 35cm H2O. End-tidal CO2 is 83mm Hg. Ventilator waveforms are shown below.

Blood gases are as follows:
Arterial: pH 7.20 PaCO2 103mm Hg PaO2 188mm Hg HCO3 44 BE +9 Hb 107g/L SaO2 98%
Venous: pH 7.15 PvCO2 110mm Hg PvO2 50mm Hg HCO3 44 SvO2 70%

1.  Describe the mechanism of hypercarbia and calculate the CO2 gradient (2 marks)

2. Calculate compliance, both dynamic and static (2 marks)

3. Calculate resistance (1 mark)

4. Calculate expiratory time and time constant, compare expiratory time to time constant and explain the relevance (3 marks)

5. Calculate PAO2 and A-a gradient (2 marks)

6. Calculate oxygen content & extraction ratio (2 marks)