Mechanical Ventilation Weaning

Question 1

What is the definition of weaning success?

Answer 1

The absence of ventilatory support 48 hours following extubation.

Question 2

What mode of ventilation is designed to make automatic adjustments from the time ventilation is initiated until ventilation can be discontinued?

Answer 2

ASV

Question 3

What 3 approaches are commonly used to reduce ventilatory support?

Answer 3

SIMV, CPAP, and T-piece

Question 4

What parameters are within the patient’s control during PSV?

Answer 4

The patient controls the rate, inspiratory time, and depth of each breath.

Question 5

What is the major disadvantage of T-piece weaning?

Answer 5

It requires a high level of staff attention.

Question 6

What is the major advantage of using CPAP instead of a T-piece trial?

Answer 6

CPAP provides continuous monitoring of the patient and backup ventilator modes in case of apnea.

Question 7

What weaning mode delivers a set tidal volume in a pressure mode of ventilation?

Answer 7

Volume Support

Question 8

Your patient’s total parenteral nutrition was set inappropriately low while receiving mechanical ventilation. What implication does this have on her ability to be weaned from the ventilator?

Answer 8

Underfeeding results in muscle wasting (diaphragm, heart, and other organs). Malnutrition also can lead to a reduced central response to hypoxemia and hypercapnia and to an impaired immune response.

Question 9

What is the procedure for a cuff leak test?

Answer 9

The patient is disconnected from the ventilator, the cuff is deflated, and the ET tube or tracheostomy tube is obstructed.

Question 10

In a cuff leak test, what does the measured volume that escapes from around a deflated cuff indicate?

Answer 10

A leak of less than 110 mL may indicate the presence of subglottic edema and a high risk of post-extubation stridor.

Question 11

Why is vital capacity not considered a good indicator for the discontinuing of ventilator support?

Answer 11

Because the test requires the patient’s cooperation, which is not always consistent.

Question 12

What parameter is a primary index of the inspiratory drive of a breath?

Answer 12

Airway occlusion pressure (P0.1 or P100)

Question 13

What index is used to assess the potential for respiratory muscle overload and fatigue?

Answer 13

CROP Index

This measures-Compliance, RR, oxygenation, Inspiratory Pressure

Question 14

What is the formula for RSBI?

Answer 14

The RSBI is calculated by dividing the respiratory frequency (breaths/min) by the tidal volume in liters.

Question 15

What values of an RSBI indicate that weaning may be successful?

Answer 15

Values less than 105 (range, 60-105) indicate that successful weaning is more likely.

Question 16

How does the administration of heliox aid in the treatment of partial airway obstruction and stridor caused by post-extubation glottic edema?

Answer 16

Heliox is a low-density gas that may decrease the WOB by relieving the effects of partial airway obstruction and temporarily supporting gas exchange. This may provide time for medical treatment.

Question 17

How is heliox therapy administered

Answer 17

Via a nonrebreathing mask.

Question 18

What are the factors that increase the risk of aspiration after extubation?

Answer 18

Use of muscle relaxants,

Presence of a gastric tube,

Presence of abnormal periglottic sensations,

Inability to close the glottis mechanically,

Excessive amounts of secretions,

Inability to clear secretions effectively.

Question 19

A patient is being weaned in the MMV mode. The MMV is set at 7 and the patient is breathing at a rate of 14 with a spontaneous tidal volume of 600. How much ventilatory assistance is the ventilator providing

Answer 19

No assistance is required.

Question 20

For successful weaning outcomes, the QS/QT should be what?

Answer 20

It should be less than 20% (pulmonary shunt).

Question 21

What is good to know about artificial tracheal airways and weaning?

Answer 21

There are decreases in tube inner diameter (ID) and increases in VE increase the work of breathing. The added work due to artificial airways can increase ventilator dependence. Artificial airways can increase the work of breathing nearly threefold.