Practice Quiz 2 Mods 3-4 dual control, Closed loo & APRV

What is the maximum pressure setting for PHIGH when using APRV?

35 cm H20

What are the advantages of the APRV mode?

Spontaneous breathing in APRV augments venous return and cardiac performance, Spontaneous breathing in APRV provides better ventilation to dependent lung regions, APRV improves oxygenation via prolonged periods at PHIGH which recruits lung units

What are the disadvantages of APRV mode?

Many clinicians are unfamiliar with APRV,

With APRV there can be difficulty with CO2 elimination in patients with increased airway resistance

How are patients weaned from APRV?

By decreasing the PHIGH and increasing the THIGH

Things that can occur with APRV

Too long a release time (TLOW) can interfere with oxygenation and allow lung units to collapse

Preventing complete exhalation to produce auto-PEEP helps maintain an open lung and avoid repeated collapse and re-expansion of alveoli

One of the methods of setting TLOW is to set the PEFR >50% and

Which factors influence ventilation and arterial carbon dioxide levels (PaCO₂) during Airway Pressure Release Ventilation (APRV)?

ΔP (PHIGH to PLOW), Release time (TLOW), Spontaneous breathing

Which of the following is considered one of the advantages of APRV?

It reduces the risk of ventilator-induced lung injury (VILI)

What are the appropriate initial settings when using APRV in patients with ARDS?

1.PHIGH of 15-30 cm H2O

2.THIGH of ≥4.0 seconds

3.TLOW of 0.5 to 1.0 second

What ways can you set the TLOW?

Set to 0.5 - 1.0 seconds, Set to 1 Time Constant, Set >50 and

It is important to know!

In Pressure-Regulated Volume Control (PRVC), as the patient's lung function improves, less pressure is needed to deliver the preset tidal volume. The ventilator gradually reduces the pressure, but it ensures that the pressure never falls below the established baseline level (PEEP).

It is important to know that:

In Pressure-Regulated Volume Control (PRVC), the ventilator ensures that the delivered pressure does not exceed a level that is 5 cm H₂O below the set upper pressure alarm limit

Is important to know that:

Volume Support Ventilation (VSV) primarily delivers flow-cycled breaths, but it can also switch to time-cycling if the inspiratory time is prolonged, or to pressure-cycling if airway pressure exceeds a certain threshold

Proportional Assist Ventilation (PAV)

The clinician sets the ventilator's volume and flow assist based on approximately 70% of the patient's lung elastance and airway resistance, which tend to decrease as the patient's condition improves. This mode supports only assisted breaths. The ventilator detects the patient's spontaneous breathing efforts—specifically flow and volume—and responds by delivering proportional pressure assistance to enhance the patient's own effort.

Volume Assured Pressure Support (VAPS)

This dual-control ventilation mode delivers pressure-limited breaths while aiming to achieve a specific tidal volume with each breath. Initially, the ventilator provides a pressure-supported breath. As inspiratory flow declines, it evaluates whether the delivered volume meets the target. If the target volume is reached before the flow drops to the preset percentage of peak flow, the ventilator transitions to exhalation—functioning like a typical pressure support breath. However, if the tidal volume is insufficient, the ventilator maintains a constant flow at the set peak flow rate until the target volume is delivered, effectively making the breath volume-cycled.

Mandatory Minute Ventilation (MMV)

The clinician sets a minimum minute ventilation, typically between 70% and 90% of the patient's current minute ventilation. The ventilator compensates for any shortfall in the patient's spontaneous breathing by increasing either the respiratory rate or the preset pressure. As the patient's own ventilation improves, the ventilator automatically reduces its level of support.

Volume Support Ventilation (VSV)

This mode delivers breaths that are triggered by the patient, aim to reach a set tidal volume, and are flow-cycled. It automatically adjusts the pressure—either increasing or decreasing—to ensure the target volume is achieved. It's commonly used for patients who are breathing spontaneously but still need partial support, especially during the weaning process from mechanical ventilation.

Pressure Regulated Volume Control (PRVC)

Delivers patient or timed triggered, volume-targeted, time-cycled breaths. Measures VT delivered with VT set on the controls. If delivered VT is less or more, ventilator increases or decreases pressure delivered until set VT and delivered VT are equal.

What is the aim of APRV

To increase the mean airway pressure (P ̅aw), and to allow recruitment of alveoli while allowing the patient to breathe spontaneously.

Is important to know that:

Airway Pressure Release Ventilation (APRV) is a ventilatory mode based on the 'open lung' strategy, designed to optimize and sustain alveolar recruitment throughout the entire breathing cycle.

You are the therapist on the floor and are asked to transition a patient with ARDS from VC-AC to APRV. The current VC-AC settings are as follows: f 12 breaths/min, VT 500 mL, FiO2 1.0, PEEP 10 cm H2O, PIP 33 cm H2O, PPLAT 20 cm H2O. Select the most appropriate APRV settings.

Remember for this case study you are switching the patient to APRV please follow the guidelines that are on the power point. You must set and PHIGH, PLOW, THIGH, the TLOW. What are you going to set?

An ARDS patient was placed on APRV at the following settings: PHIGH 30 cm H2O, PLOW 0 cm H2O, THIGH 4.5 s, TLOW 0.5 s, FiO2 0.50. The following values are being display on the ventilator's monitors: f 12, no spontaneous respirations, mPaw 25, VTE 700 mL, VE 8.9 L/min, The ABG results on those settings are as follows: pH 7.52, PaCO2 28, PaO2 100, HCO3 22 mEq/L. Which of the following is the most appropriate action to take at this time.

Think about it carefully. What changes is it asking you to make based on your patient's abg and ventilator monitor.

You have a patient with ARDS who is being mechanically ventilated using APRV at the following settings: PHIGH 25 cm H2O, PLOW 0 cm H2O, THIGH 5.5 s, TLOW 0.5 s, FiO2 0.30. The ABG results on those settings are as follows: pH 7.37, PaCO2 45, PaO2 52, HCO3 22 mEq/L. What is the most appropriate action to take at this time?

Look at you ABG and your settings closely and figure out what appropriate change needs to be made.