Question 1

Beneficial effects of using high inspiratory flows in patients with chronic airflow obstruction receiving flow-limited mechanical ventilation include which of the following?
1) Decreased work of breathing
2) Improved gas exchange
3) Decreased auto-PEEP

Accepted Answer

Using high inspiratory flows in patients with chronic airflow obstruction receiving flow-limited mechanical ventilation can have several beneficial effects. Firstly, it can decrease the work of breathing as it helps to overcome the increased resistance in the airways. Secondly, it can improve gas exchange by promoting better ventilation-perfusion matching and increasing the tidal volume. Lastly, it can decrease auto-PEEP (positive end-expiratory pressure) by allowing for more complete exhalation and preventing air trapping. Therefore, all three options (1, 2, and 3) are correct.

Question 2

Which of the following is false about flow triggering of spontaneous breaths during mechanical ventilation?

Accepted Answer

Flow triggering may not be effective in reducing work of breathing because of the presence of a small endotracheal tube or auto-PEEP.

Question 3

Which of the following would decrease PaCO₂ when ventilating a patient using intermittent mandatory ventilation with pressure support?

Accepted Answer

The PaCO₂ can be decreased by increasing tidal volume, increasing PSV for spontaneous breaths, or increasing the machine rate.

Question 4

In which of the following clinical situations is the incidence of auto-PEEP the greatest?
1) Patients with high respiratory rates
2) Intubated patients with obstructive lung disease
3) Patients with low minute volumes

Accepted Answer

Auto-PEEP (positive end-expiratory pressure) is most commonly seen in patients with high respiratory rates and those with obstructive lung disease, as both conditions can prevent complete exhalation before the next breath begins, leading to air trapping and increased intrathoracic pressure.

Question 5

Which of the following ventilator adjustments would decrease inspiratory time?
1) Increase the peak flow.
2) Increase the tidal volume.
3) Change the flow pattern from a decelerating wave to a square wave.

Accepted Answer

1) Increasing the peak flow would decrease inspiratory time because it would deliver the set tidal volume more quickly.
2) Increasing the tidal volume would increase inspiratory time if the flow rate remains constant, but it is not a specific option for decreasing inspiratory time.
3) Changing the flow pattern from a decelerating wave to a square wave would decrease inspiratory time because all of the tidal volume would be delivered at the set peak flow rate without deceleration.

Question 6

Which of the following trigger levels is appropriate when setting a ventilator for flow triggering?

Accepted Answer

In general, for flow triggering the trigger flow should be set 1 to 2 L/min below baseline or bias flow.

Question 7

What flow pattern is least optimal for ventilating a patient with cardiovascular instability?

Accepted Answer

A square or even accelerating waveform may be useful in reducing mean airway pressure in patients with severe hypotension or cardiovascular instability.

Question 8

When starting flow-limited ventilatory support on an adult patient, which of the following inspiratory flow settings would you initially select?

Accepted Answer

This value corresponds to an initial peak flow setting of approximately 60 L/min with a range of 40 to 80 L/min and a down ramp or square flow waveform.

Question 9

An adult patient in respiratory failure has the following blood gases on a nasal cannula at 5 L/min: pH = 7.20; PaCO₂ = 67 mm Hg; HCO₃^-= 27 mEq/L; PaO₂ = 89 mm Hg. The attending physician orders intubation and ventilatory support. What FiO₂ would you recommend to start with?

Accepted Answer

Patients who have undergone previous blood gas measurement or oximetry who are doing well clinically and patients with disease states or conditions that normally respond to low to moderate concentrations of O₂ may begin ventilation with 50% to 70% O₂.

Question 10

When adjusting the FiO₂ setting for a patient receiving mechanical ventilatory support, what should your goal be?

Accepted Answer

After initiation of mechanical ventilation with an FiO₂ of 1.0, the FiO₂ should be reduced to 0.40 to 0.50 or less as soon as is practical to avoid O₂ toxicity and absorption atelectasis.

Question 11

Which of the following is false about flow-triggered ventilatory support?

Accepted Answer

Flow triggering may not be effective in reducing work of breathing because of the presence of a small endotracheal tube or auto-PEEP.

Question 12

Which of the following criteria represents the recommended starting point for considering the use of PEEP?

Accepted Answer

The recommended starting point for considering the use of PEEP is when the PaO2 is less than 60 mmHg on an FiO2 of greater than 0.5 or less than 50 mmHg on an FiO2 of greater than 0.6. Choice B best matches this criteria.

Question 13

In which of the following conditions is PEEP likely to be useful?
1) ARDS
2) Pulmonary edema
3) Acute lung injury
4) Neuromuscular disease

Accepted Answer

PEEP (Positive End-Expiratory Pressure) is beneficial in conditions where alveolar collapse is a concern, such as ARDS (Acute Respiratory Distress Syndrome), pulmonary edema, and acute lung injury, by keeping the airways open during expiration, thus improving oxygenation. It is not typically used for neuromuscular diseases, which affect the muscles rather than the structure or function of the airways and alveoli.

Question 14

Immediately after cardiac arrest and resuscitation, a patient is placed on a ventilator in the continuous mandatory ventilation assist-control mode. What initial FiO₂ would you recommend?

Accepted Answer

Examples of disease states or conditions that typically warrant an initial FiO₂ of 1.0 include acute pulmonary edema, ARDS, near drowning, cardiac arrest, severe trauma, suspected aspiration, severe pneumonia, carbon monoxide poisoning, and any disease state or condition resulting in a large right-to-left shunt.

Question 15

To prevent atelectasis and improve gas exchange, most thoracic surgery patients placed on ventilatory support receive which of the following?

Accepted Answer

In terms of ventilator initiation, initial PEEP/CPAP levels usually are 5 cm H₂O.

Question 16

A chronic obstructive pulmonary disease (COPD) patient receiving ventilatory support in the CMV assist-control mode at a rate of 14 and a V_T of 750 ml exhibits clinical signs of air trapping. Which of the following would you recommend to correct this problem? 1) Decrease "E" time. 2) Increase the inspiratory flow rate. 3) Decrease the assist-control rate.

Accepted Answer

Increasing the inspiratory flow rate and decreasing the assist-control rate can help reduce air trapping by allowing more time for exhalation.

Question 17

For adults with otherwise normal lungs who are receiving ventilatory support in the continuous mandatory ventilation control or assist-control mode, inspiratory flow should be set to provide what 1:E?

Accepted Answer

For most adults, an initial inspiratory time of approximately 1 sec (0.8 to 1.2 sec) with a resultant 1:E ratio of 1:2 or lower is a good starting point.

Question 18

A patient receiving continuous mandatory ventilation in the assist-control mode develops auto-PEEP. Which of the following changes in ventilatory patterns would you consider to minimize the effects of auto-PEEP in this patient? 1) Decreasing the rate or increasing V_T 2) Using low-rate synchronized intermittent mandatory ventilation 3) Decreasing the peak inspiratory flow 4) Lowering the V_T and letting the PaCO₂ rise

Accepted Answer

Auto-PEEP (positive end-expiratory pressure) occurs when air gets trapped in the lungs during mechanical ventilation, often due to insufficient expiratory time. To minimize its effects, strategies include decreasing the ventilatory rate or increasing the time for expiration (1), using low-rate synchronized intermittent mandatory ventilation to allow more time for expiration (2), and lowering the tidal volume to reduce the amount of air entering the lungs each cycle, thereby allowing CO2 levels to rise slightly if necessary for better ventilation (4). Decreasing the peak inspiratory flow (3) does not directly address the issue of insufficient expiratory time and is not a recommended strategy for minimizing auto-PEEP.

Question 19

A patient receiving continuous mandatory ventilation in the assist-control mode develops auto-PEEP. Which of the following general approaches would you consider to minimize the effects of auto-PEEP in this patient?
1) Increasing expiratory time
2) Applying PEEP
3) Switching ventilating mode to synchronized intermittent mandatory ventilation

Accepted Answer

The answer of A patient receiving continuous mandatory ventilation in...

Question 20

Which of the following statements is false regarding the use of an inspiratory pause during mechanical ventilation?

Accepted Answer

The use of a single long inspiratory pause (up to 40 sec) has been advocated in the management of acute lung injury/ARDS as a lung recruitment maneuver, and the results have been encouraging. Use of an inspiratory pause has been suggested for administration of bronchodilators to improve medication delivery. In the treatment of chronic obstructive pulmonary disease patients, however, a 5-sec inspiratory pause did not result in significant improvement in measures related to the effectiveness of the bronchodilator. If a brief inspiratory pause is used, 1:E ratio and mean airway pressure increase. An inspiratory pause of 0.5 to 1.0 sec applied for a single breath is used for measurement of plateau pressure (P_plat) and in estimation of airway resistance (Raw) where PIP is peak inspiratory pressure and is inspiratory peak flow (square wave). An inspiratory pause can also be used to ensure a full inspiration before a chest radiograph is obtained, and this step may improve the quality of the resulting radiograph.

Quiz 48: Initiating and Adjusting Invasive Ventilatory Support

Beneficial effects of using high inspiratory flows in patients with chronic airflow obstruction receiving flow-limited mechanical ventilation include which of the following? 1) Decreased work of breathing 2) Improved gas exchange 3) Decreased auto-PEEP

Which of the following is false about flow triggering of spontaneous breaths during mechanical ventilation?

Which of the following would decrease PaCO2 when ventilating a patient using intermittent mandatory ventilation with pressure support?

In which of the following clinical situations is the incidence of auto-PEEP the greatest? 1) Patients with high respiratory rates 2) Intubated patients with obstructive lung disease 3) Patients with low minute volumes

Which of the following ventilator adjustments would decrease inspiratory time? 1) Increase the peak flow. 2) Increase the tidal volume. 3) Change the flow pattern from a decelerating wave to a square wave.