Quiz 10: Ventilation Weaning and Support - Quiz Review

Vent Support I - Quiz 10

Question 1

• Question: Which intubated and mechanically ventilated patient is most likely to require slow liberation from mechanical ventilation?
• Options:
  • A patient who overdosed on diazepam
  • A postoperative patient who had knee surgery
  • A patient with a severe exacerbation of asthma
  • A patient with chest contusions from a motor vehicle crash
• Answer: A patient with a severe exacerbation of asthma. Asthma exacerbations may cause prolonged respiratory muscle weakness and airway inflammation, leading to a longer weaning process.

Question 2

• Scenario: A patient is being weaned from invasive mechanical ventilation using VC-IMV.
• Data:
  • 0630: Set VT = 650 mL, Spontaneous VT = 410 mL, Set Rate = 8 breaths/min, Spontaneous Rate = 6 breaths/min
  • 1020: Set VT = 650 mL, Spontaneous VT = 400 mL, Set Rate = 6 breaths/min, Spontaneous Rate = 10 breaths/min
  • 1600: Set VT = 650 mL, Spontaneous VT = 320 mL, Set Rate = 4 breaths/min, Spontaneous Rate = 20 breaths/min
  • 2200: Set VT = 650 mL, Spontaneous VT = 250 mL, Set Rate = 2 breaths/min, Spontaneous Rate = 32 breaths/min
• Question: What should the respiratory therapist recommend?
• Options:
  • Switch the mode to VC-CMV.
  • Add and titrate pressure support.
  • Extubate and place the patient on NIV.
  • Increase the set rate to 8 breaths/min.
• Answer: Add and titrate pressure support. The patient's spontaneous tidal volumes are decreasing while the spontaneous rate is increasing, suggesting increased work of breathing. Adding pressure support can help augment the spontaneous breaths.

Question 3

• Question: What ends inspiration in pressure support ventilation (PSV)?
• Options:
  • Time
  • Flow
  • Volume
  • Pressure
• Answer: Flow. In PSV, inspiration ends when the inspiratory flow decreases to a certain percentage of the peak inspiratory flow (typically 25% to 50%), or when a maximum inspiratory time is reached.

Question 4

• Question: At what pressure is pressure support sufficient to overcome the work imposed by the ventilator system but not high enough to contribute significantly to ventilatory support?
• Options:
  • 2 cm H2O
  • 5 cm H2O
  • 8 cm H2O
  • 10 cm H2O
• Answer: 5 cm H2O. A pressure support of around 5 cm H2O is often used to overcome the resistance of the endotracheal tube and ventilator circuit, without providing significant ventilatory assistance. This level is often referred to as "minimal" or "threshold" PSV.

Question 5

• Question: Which mode of ventilation delivers the exact amount of pressure required to overcome the resistive load imposed by the ET tube for the flow measured at the time?
• Options:
  • Automode
  • Volume-targeted PSV
  • Pressure support ventilation
  • Automatic tube compensation
• Answer: Automatic tube compensation (ATC). ATC is specifically designed to overcome the resistance of the endotracheal tube.

Question 6

• Question: What mode of ventilation maintains a minimum VE (minute ventilation) by increasing or decreasing the amount of support (VT or respiratory rate) given to the patient?
• Options:
  • Volume support
  • Automatic tube compensation
  • Mandatory minute ventilation
  • Adaptive support ventilation
• Answer: Mandatory minute ventilation (MMV). MMV ensures a minimum minute ventilation by adjusting either the delivered tidal volume or the ventilator rate based on the patient's spontaneous breathing effort. If the patient's spontaneous minute ventilation drops below the set target, the ventilator increases its support to meet the target.

Question 7

• Question: Which of the following is considered a closed-loop mode used for weaning from mechanical ventilation?
• Options:
  • Pressure support ventilation
  • Adaptive support ventilation
  • Continuous positive airway pressure
  • Intermittent mandatory ventilation
• Answer: Adaptive support ventilation (ASV). ASV is a closed-loop mode that automatically adjusts ventilator parameters to achieve a target minute ventilation while considering the patient's respiratory mechanics.

Question 8

• Question: Assess the following data obtained from the spontaneous breathing trials (SBT) of four patients. Which patient is most likely to be weaned successfully at this time?
• Options:
  • Spontaneous rate = 32 breaths/min, VT = 375 mL, PaO2 = 98 mm Hg, FIO_2 = 0.4
  • Spontaneous rate = 15 breaths/min, VT = 450 mL, PaO2 = 87 mm Hg, FIO_2 = 0.6
  • Spontaneous rate = 15 breaths/min, VT = 650 mL, PaO2 = 91 mm Hg, FIO_2 = 0.28
  • Spontaneous rate = 12 breaths/min, VT = 680 mL, PaO2 = 79 mm Hg, FIO_2 = 0.5
• Answer: Spontaneous rate = 15 breaths/min, VT = 650 mL, PaO2 = 91 mm Hg, FIO2 = 0.28. This patient has a stable respiratory rate, adequate tidal volume, acceptable oxygenation at a relatively low FIO2, indicating a higher likelihood of successful weaning.

Question 9

• Scenario: A 46-year-old male patient (IBW = 85 kg) injured in a motor vehicle crash has been receiving invasive mechanical ventilation for 24 hours. The patient is awake, alert, and comfortable on VC-IMV with pressure support of 5 cm H2O; set rate = 8 breaths/min; set VT = 500 mL; FIO2 = 0.4; PEEP = 5 cm H2O.
• Data: A 10-minute spontaneous breathing trial (SBT) yields: f = 30 breaths/min, RSBI = 145, P0.1 = 10 cm H2O.
• Question: What should the respiratory therapist suggest to the physician during patient rounds?
• Options:
  • Sedate the patient and place him on VC-CMV.
  • Continue with the current ventilator settings.
  • Switch to PC-CMV with a rate of 14 breaths/min.
  • Decrease the mandatory IMV rate to 4 breaths/min.
• Answer: Continue with the current ventilator settings. Despite the elevated respiratory rate (f) and RSBI, a single 10-minute trial is insufficient to determine weaning failure definitively. The P0.1 (occlusion pressure) is very high, indicating a strong respiratory drive, which may suggest the need to address the underlying cause of this drive. However, the best immediate course is to continue monitoring and reassess. Note: RSBI = /V_T = 30/0.5 = 60. A RSBI over 105 is generally considered predictive of weaning failure, but in this example the spontaneous VT of 500ml was used rather than the Ideal Body Weight.

Question 10

• Question: What is the longest time an SBT should last?
• Options:
  • 30 minutes
  • 60 minutes
  • 120 minutes
  • 180 minutes
• Answer: 120 minutes. SBTs are typically conducted for 30 to 120 minutes to assess a patient's ability to breathe spontaneously.

Question 11

• Question: A recently extubated patient develops a partial upper airway obstruction, which causes stridor. What action can the respiratory therapist take to improve the patient’s condition?
• Options:
  • Nebulize racemic epinephrine (0.5 mL, 2.25% epinephrine in 3 mL normal saline).
  • Put a nonrebreather mask on the patient.
  • Place the patient on NIV.
  • Suggest the use of lorazepam (Ativan).
• Answer: Nebulize racemic epinephrine (0.5 mL, 2.25% epinephrine in 3 mL normal saline). Racemic epinephrine is a vasoconstrictor that can reduce upper airway edema and relieve stridor.

Question 12

• Scenario: A female intubated patient has been weaned from full ventilatory support to PSV 5 cm H2O, CPAP 5 cm H2O, and an FIO_2 of 0.3. The patient is alert and oriented and doing well. The respiratory therapist performs a cuff leak test.
• Data: The average peritubular leak is 70 mL.
• Question: The respiratory therapist should recommend which of the following?
• Options:
  • Maintain the patient on the current settings and redo the cuff leak test in 24 hours.
  • Increase the PSV to 10 cm H2O and maintain the CPAP and FIO_2.
  • Extubate the patient and place her on a heated aerosol generator with an FIO_2 of 0.4.
  • Pretreat the patient with steroids and/or racemic epinephrine before extubation.
• Answer: Pretreat the patient with steroids and/or racemic epinephrine before extubation. A cuff leak of 110mL or greater is an indicator for successful extubation. A leak less than is predictive of post-extubation stridor. Given the low cuff leak volume, pretreating with steroids and/or racemic epinephrine can help reduce the risk of post-extubation stridor.

Question 13

• Scenario: A patient is extubated and placed on a cool, bland aerosol with 30% oxygen. Twenty minutes post extubation, the respiratory therapist assesses the patient, who has shortness of breath.
• Observations: Intercostal retractions, accessory muscle use, a respiratory rate of 38 breaths/min, stridor without a stethoscope, and SpO2 has dropped from 97% to 85%.
• Intervention: The patient is given an aerosolized racemic epinephrine treatment and reassessed.
• Post-Treatment Assessment: Accessory muscle use continues, intercostal retractions decrease slightly, and stridor is heard on auscultation. The patient’s respiratory rate is 30 breaths/min and the SpO2 is 88%.
• Question: What should the respiratory therapist recommend?
• Options:
  • Reintubation and mechanical ventilation
  • Heliox therapy and steroid administration
  • Increase the FIO_2 on the cool bland aerosol to 40%
  • Use a nonrebreather mask with 15 L/min oxygen.
• Answer: Reintubation and mechanical ventilation. Despite the slight improvement after racemic epinephrine, the patient still exhibits significant signs of respiratory distress (accessory muscle use, high respiratory rate, decreased SpO2), indicating that the current interventions are insufficient. Reintubation is necessary to secure the airway and provide adequate ventilation.

Question 14

• Question: If a patient who has failed an SBT still meets the criteria for discontinuation of ventilation, when should an SBT be performed to determine weanability?
• Options:
  • Every 6 hours
  • Every 12 hours
  • Every 24 hours
  • Every 36 hours
• Answer: Every 24 hours. If a patient fails an SBT but continues to meet general weaning criteria, another SBT should be performed every 24 hours to reassess readiness for weaning.

Question 15

• Question: A patient in the ICU who has successfully completed a 120-minute SBT requires extubation. Which of the following tests or values would indicate the potential for airway edema after extubation?
• Options:
  • PImax
  • VC
  • Cuff leak test
  • Oxygen saturation measured by pulse oximeter (SpO2)
• Answer: Cuff leak test. The cuff leak test assesses the presence of airway edema by measuring the difference in exhaled tidal volume with the endotracheal tube cuff inflated versus deflated. A reduced cuff leak indicates potential airway edema, increasing the risk of post-extubation stridor and respiratory distress.