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SELECTING THE VENTILATOR & MODES OF
VENTILATION PRACTICE EXAM NEW
QUESTIONS AND ANSWER
- List seven questions that the clinician should ask when determining the appropriate ventilator and mode of ventilation. - Answer: (a) Why does the patient need ventilatory support? (Indication) (b) Does the ventilatory problem require a special mechanical ventilation mode? (Pathology) (c) What therapeutic goals can be achieved by using a specific ventilator? (Treatment goals) (d) Does the patient need to be intubated, or can a mask be used? (Patient interface) (e) Will the ventilatory support be provided in the intensive care unit, the patient's home, or an extended-care facility? (Location) (f) Will ventilatory support be required for a brief period or long term? (Duration) (g) How familiar is the staff with the ventilator (or ventilators) under consideration? (Staff training) Match the appropriate ventilation support type with the appropriate ventilator connection or interface (there may be more than one answer): § Negative pressure ventilation § CPAP § Positive pressure ventilation § Noninvasive positive pressure ventilation A. Oral endotracheal tube B. Nasal mask C. Face mask D. Chest cuirass E. Tracheostomy tube - Answer: D—Negative pressure ventilation A, B, C, and E—Continuous positive airway pressure (CPAP) A, E—Positive-pressure ventilation B, C—Noninvasive positive-pressure ventilation CPAP is commonly used in the hospital setting as a method to while in the home- care setting it is typically used when treating. - Answer: Improving oxygenation, obstructive sleep apnea Acute-on-chronic respiratory failure is most often treated with which type of noninvasive positive pressure ventilation (NIV)? - Answer: Bilevel positive airway pressure
Name a type of ventilation that reduces the requirements for heavy patient sedation - Answer: Noninvasive positive-pressure ventilation (NIV) List five disorders that are sometimes managed with NIV. a. b. c. d. e - Answer: (any five of the following) (1) chronic respiratory failure, (2) chest wall deformities, (3) neuromuscular disorders, (4) central alveolar hypoventilation, (5) COPD, (6) CF, (7) bronchiectasis, (8) ARF, (9) ARDS, (10) PNA, (11) postoperative complications, (12) asthma, (13) heart failure, (14) postextubation failure in difficult-to-wean patients, and (15) obstructive sleep apnea. List both advantages and disadvantages of NIV in a patient with acute respiratory failure. - Answer: Advantages · Avoids complications associated with artificial airways · Provides flexibility in initiating and removing mechanical ventilation · Reduces requirements for heavy sedation · Preserves airway defense, speech, and swallowing mechanisms · Reduces need for invasive monitoring Disadvantages · Can cause gastric distention, skin pressure lesions, facial pain, dry nose, eye irritation (conjunctivitis), discomfort, claustrophobia, and poor sleep, and mask leaks can occur Define the terms full ventilatory support (FVS) and partial ventilatory support (PVS). - Answer: In full ventilatory support, the ventilator provides all the energy necessary to maintain the patient's effective alveolar ventilation. In partial ventilatory support, the patient participates in the work of breathing to help maintain effective alveolar ventilation. The typical minimum ventilatory rate setting for a patient receiving FVS is considered breaths/min. - Answer: 8 breaths/min PVS typically uses set machine rates of lower than breaths/min with the patient participating in the WOB to help maintain effective alveolar ventilation. - Answer: 6 breaths/min What type of ventilatory support would you consider using when your patient has acute ventilatory failure from ventilatory muscle fatigue or a high WOB? Why? - Answer: Full ventilatory support allows the ventilatory muscles to rest while the machine supplies all the necessary ventilation. List and explain the three types of breath delivery. a.
What are three disadvantages of PCV? a. b. c. - Answer: (a) Volume delivery varies as the patient's lung characteristics change. (b) Clinicians are less familiar with pressure control. (c) Tidal volume and minute ventilation decrease when lung characteristics deteriorate. When a patient's lung compliance worsens during PCV, what will happen to tidal volume being delivered? - Answer: It will decrease. What are the three types of breath delivery timing or sequence available on current Intensive Care Unit (ICU) ventilators? Briefly describe each. a. b. c. - Answer: (a) Continuous mandatory ventilation—either time- or patient-triggered breaths are mandatory, the patient is not generating any spontaneous breaths. (b) Intermittent mechanical ventilation—the patient receives a set number of mandatory breaths each minute but is also allowed to breathe spontaneously between mandatory breaths. (c) Continuous spontaneous ventilation—all breaths are spontaneous and are therefore patient-triggered. These spontaneous breaths may be assisted or unassisted. What three characteristics determine the mode of ventilation? a. b. c. - Answer: (a) Breath type (b) the targeted control variable (c) the timing of the breath delivery List the five basic modes of ventilation - Answer: (a) Breath type (b) the targeted control variable (c) the timing of the breath delivery How should clinicians differentiate between controlled and assisted ventilation? - Answer: (a) VC-CMV (b) PC-CMV (c) VC-IMV (d) PC-IMV (e) CSV
Give a clinical situation where assist-controlled ventilation is appropriate? - Answer: When a patient is obtunded because of drugs, cerebral malfunction, spinal cord or phrenic nerve injury, or motor nerve paralysis that makes him or her unable to produce any voluntary efforts to breathe. What happens when the clinician inappropriately sets ventilator sensitivity? - Answer: If it is too sensitive, accidentally triggering or ventilator self-triggering can occur. If not sensitive enough, it will require too much patient effort to trigger. What two triggers can begin inspiration in patient- triggered assisted ventilation? - Answer: Time triggered, and patient triggered (pressure or flow) Studies have shown that vital capacity (VC)-CMV may actually increase the patient's WOB by %. How is this observed in the clinical setting? How is this corrected? - Answer: 33-50, watching the pressure manometer or the pressure-time curve, typically by increasing the inspiratory flow What settings are typically set by the clinician in PC-CMV? - Answer: Inspiratory time, pressure level, rate, FIO2, PEEP, and apnea settings. What determines the tidal volume delivered in PC-CMV? - Answer: Depends on the compliance and resistance of the patient's lungs, patient effort, and the set pressure What flow-curve type has been shown to improve gas distribution and allow the patient to vary inspiratory gas flow during spontaneous breathing efforts? - Answer: Decelerating ramp A safety mechanism to avoid excessive system pressure is the and is set at about above the set pressure level and will cause to end when reached. - Answer: Maximum pressure limit; +10 cm H2O inspiration Describe a clinical scenario where pressure control inverse ratio ventilation (PC-IRV) would be appropriate? - Answer: PC-IRV is appropriate when a patient with very stiff lungs is not successfully ventilated with VC-CMV and PEEP or PC-CMV and PEEP. Explain how IMV differs from CMV? - Answer: IMV differs from CMV because IMV allows the patient to breathe spontaneously between mandatory breaths. In CMV, all breaths are machine breaths. Fill in the table below regarding the advantages, risks, and disadvantages of CMV and IMV. Mode Advantages Risks and Disadvantages VC-CMV or PC-CMV
What patient variables can end inspiration in the bilevel pressure-assist mode? - Answer: Patient coughing or forcible exhalation will cause a ventilator to pressure cycle What patient characteristic can influence the specific time and pressure limits used during PSV?
- Answer: The size of the patient (infant, child, and adult) Explain how pressure augmentation (PAug) works? What is an alternate term used to describe P(aug)? - Answer: Pressure augmentation (PAug) is a dual-control mode that provides pressure- limited ventilation with volume delivery targeted for every breath. (Another term that is used to describe this mode is volume-assured pressure support (VAPS). VAPS is the term used to describe this mode on the Bird 8400st (CareFusion, Viasys Corp, San Diego, Calif.). Each breath in PAug is patient triggered and pressure targeted, such as a pressure-supported breath. However, PAug guarantees that at least the volume set on the control panel is delivered for each breath. In PAug, if the set volume is achieved prior to flow cycling, what will happen to the breath? - Answer: If the set volume is achieved prior to flow cycling, the breath is volume cycled. In PAug, if the set volume is not reached before flow drops to the set level, how will the ventilator respond? - Answer: If the set volume is not reached before flow drops to the set level, the ventilator maintains the flow at its set value until the volume is delivered (volume cycled). Describe a clinical scenario where a patient can receive more volume than is set by the clinician in PAug? - Answer: The patient can receive more volume than is set in PAug if the patient's inspiratory flow demand is high enough to prevent maintenance of the set pressure level. This causes the ventilator to provide additional flow to the patient. Describe PRVC in terms of trigger, limit, and cycle. - Answer: PCRV is patient or time triggered, pressure limited (volume targeted), and time cycled. Fill in the table below regarding the different proprietary names given to PRVC Ventilator Pressure-regulated volume control name Carefusion Avea. Covidien PB 840. Hamilton G5 and G. Dräger Evita XL and V. Servoi. - Answer: on image Generally, at what pressure will a ventilator alarm while in the PRVC mode if the upper pressure limit is set at 40 cm H2O and the tidal volume is set at 600 mL? - Answer: The ventilator will not allow the pressure to rise higher than 5 cm H2O below the upper pressure limit setting. Therefore, at 35 cm H2O, the alarm will activate.
Describe volume-support ventilation (VSV) in terms of trigger, limit, and cycle. - Answer: Patient triggered (pressure or flow triggered), pressure limited (volume targeted), and flow cycled. What is the difference between PRVC and VSV? - Answer: With PRVC, inspiration can be either time triggered, or patient triggered. In VS, inspiration is only patient triggered. A PRVC breath is time cycled, whereas a VS breath is usually flow cycled (it may pressure cycle if pressure rises too high or time cycle if the inspiratory time is extended for some reason). Define MMV. - Answer: Mandatory minute ventilation (MMV), also called minimum minute ventilation and augmented minute ventilation, is used primarily for weaning patients from the ventilator. It allows the operator to set a minimum minute ventilation, which usually is 70-90% of the patient's current. The ventilator provides whatever part of the minute ventilation that the patient is unable to accomplish by increasing the breathing rate or by increasing the preset pressure. The ventilator monitors the patient's spontaneous breathing and provides additional ventilatory support if the patient does not achieve the set. If a patient increases the level of his or her spontaneous ventilation, the ventilator reduces its amount of support. In MVV, what alarms must be set to protect against problems associated with rapid, shallow breathing? - Answer: In MVV, the high rate alarm and the low VT alarm must be set to protect against rapid, shallow breathing by the patient. The mode of ventilation that requires two levels of CPAP and allows the patient to breath spontaneously at both levels is known as - Answer: Airway pressure-release ventilation (APRV) The optimum duration of the release time for the mode mentioned in Question 60 is a function of the system. of the respiratory - Answer: Time constant APRV was originally intended to ventilate patients with. - Answer: Stiff Lungs With PAV, what three variables are proportional to the patient's spontaneous effort? - Answer: Pressure, flow, and volume delivery In PAV mode what two factors determine the amount of pressure produced by the ventilator? - Answer: In PAV, (a) the amount of pressure produced by the ventilator depends on the patient's demand for inspiratory flow and volume and (b) the amplification setting selected by the clinician. What are the advantages and disadvantages of PAV? - Answer: The advantage of PAV is the ability to track changes in patient effort. Disadvantages are that PAV provides only for assisted ventilation; it cannot compensate for system leaks, and it may be more difficult for the patient to trigger in the presence of auto-PEEP.
(5) Intubated with consistent spontaneous respiratory pattern. (6) Nonintubated spontaneously breathing with refractory hypoxemia (7) Intubated with drug overdose. - Answer: d. VC-CMV (1)—Intubated with quadriplegia from a spinal cord injury Rationale: Patient will most likely be unable to breathe without full ventilatory support. e. PC-CMV with PEEP (2)—Intubated with acute respiratory distress syndrome Rationale: With ARDS it is important to guard against increasing peak pressures due to stiff lungs. a. Nasal mask CPAP (3)—Obstructive sleep apnea at home Rationale: This will keep the upper airways open so that the patient can breathe spontaneously. b. CPAP through ventilator (4)—Intubated with spontaneous breathing with ARDS Rationale: This will improve oxygenation while allowing the patient to be monitored. Patient would also benefit from pressure support. c. Pressure support (5)—Intubated with consistent spontaneous respiratory pattern Rationale: This will help the patient to overcome the resistance due to the endotracheal tube, ventilator circuit, and demand valve system while allowing the patient to be monitored. a. Nasal mask CPAP (6)—Nonintubated, spontaneously breathing with refractory hypoxemia Rationale: This will improve oxygenation without having to intubate the patient. This, hopefully, will avoid intubation. d. VC-CMV (7)—Intubated with drug overdose Rationale: Patient will require full ventilatory support until the effects of the drugs wear off. Case Study 1 In the ICU the respiratory therapist approaches a patient receiving mechanical ventilation. The ventilator monitor shows the following scalar. - 1. What mode of ventilation is the ventilator set to deliver? Answer: The ventilator is set to deliver PC-SIMV.
- What is the inspiratory time for the mechanical breaths? Answer: The inspiratory time is 1 second.
- What is the ventilator expiratory time? Answer: The expiratory time is 3.0 seconds Case Study 2 A 6-foot 3-inch male patient who was involved in a motor vehicle crash (MVC) arrives in the emergency department with chest and facial injuries. Because of the nature of the facial
injuries, he is intubated with a size 8.0 mm endotracheal tube. Following resuscitative measures he is transferred to the ICU.
- What type of ventilator support would this patient require initially?
- What ventilator mode would you use when this patient wakes, has the desire to breathe spontaneously, and hasaPaO2 of 58mmHg with the FIO2 set at 0.50? - 1. What type of ventilator support would this patient require initially? Answer: Full ventilatory support to ensure adequate ventilation.
- What ventilator mode would you use when this patient wakes, has the desire to breathe spontaneously, and has a PaO2 of 58mmHg with the FIO2 set at 0.50? Answer: PC-SIMV with pressure support and PEEP. Pressure control may be necessary to guard against high inspiratory pressures. Pressure support to overcome the airway resistance caused by the small ET tube and ventilator circuit and PEEP for the refractory hypoxemia. If peak pressures are not an issue, VC-SIMV with pressure support and PEEP may be used. Graph - 1. What mode of ventilation does Figure 5-2 represent? Answer: The scalar represents pressure support ventilation (PSV).
- Identify the issue with this pressure tracing. Answer: The problem is pressure overshoot at the beginning of inspiration.
- What can be done to resolve the identified problem? Answer: To correct this problem, slow down the rise time. NBRC-STYLE QUESTIONS
- When switching from the CMV mode to the IMV mode to facilitate weaning from mechanical ventilation, which of the following could be used, in addition to IMV (IMV), to assist in this process? a. PCV b. PSV c. PAV d. APRV - Answer: b. PSV NBRC-STYLE QUESTIONS
- A post-thoracic surgery patient currently receiving mechanical ventilation on VC-CMV with 60% oxygen has the following arterial blood gas (ABG): pH 7.45, PaCO2 36 mm Hg, PaO2 68 mm Hg. The patient's peak inspiratory pressures are averaging 55 cm H2O. The ventilator mode that is most appropriate at this time is which of the following? a. PSV b. VC-IMV with PEEP
c. PCV d. VC-IMV - Answer: c. PCV NBRC-STYLE QUESTIONS
- Pressure augmentation (PAug) may be beneficial for mechanically ventilated patients with which of the following?
- Noncardiogenic pulmonary edema
- Acute Respiratory Distress Syndrome
- Postoperative upper abdominal surgery
- Receiving heavy sedation and paralyzing agents a. 1 and 2 only b. 1 and 3 only c. 2 and 4 only d. 3 and 4 only - Answer: b. 1 and 3 only NBRC-STYLE QUESTIONS
- The ventilator mode that allows the patient to breathe spontaneously at two levels of positive pressure is known as which of the following? a. CPAP b. PAug c. PRVC d. APRV - Answer: d. APRV NBRC-STYLE QUESTIONS
- When lung compliance decreases while a patient is receiving mechanical ventilation with PCV which of the will occur? a. Peak pressure will increase. b. Peak pressure will decrease. c. Tidal volume will increase. d. Tidal volume will decrease - Answer: d. Tidal volume will decrease NBRC-STYLE QUESTIONS
- A patient is intubated and on PSV. The respiratory therapist notices that inspiratory time has increased from 1 second to 2 seconds consistently on every breath since last ventilator rounds. What should be the first action the respiratory therapist should do to correct the problem? a. Change to the SIMV mode b. Check the endotracheal tube cuff pressure c. Increase the inspiratory flow setting d. Suction and lavage the patient's airway - Answer: b. Check the endotracheal tube cuff pressure
