Weaning from mechanical ventilation is the process of transferring the work of breathing from the ventilator to the patient.
Some patients can tolerate rapid weaning, which involves an abrupt termination of ventilatory support. Other patients may require gradual removal from mechanical ventilatory support in order for weaning to be successful.
In this article, we will discuss the process of ventilator weaning, including what is considered to be weaning failure and weaning success. We provided helpful practice questions on this topic as well.
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What is Ventilator Weaning?
Weaning is the process of discontinuing mechanical ventilation and allowing the patient to breathe spontaneously.
The ability to wean a patient from mechanical ventilation is dependent on many factors, including:
- Type of respiratory disease
- Severity
- Patient’s age
- Presence of comorbidities
- Length of time on the ventilator
For example, a patient who was only on the ventilator for 24 hours is more likely to experience weaning success than a patient who has been on the ventilator for weeks due to a severe respiratory illness.
In general, the longer the patient is on the ventilator, the more difficult weaning becomes.
Weaning Success
Weaning success is defined as the patient being able to tolerate spontaneous breathing for 48 hours following extubation without the need for reintubation.
Surgical patients are more likely to experience weaning success than those with a chronic disease. Patients who are younger, have fewer comorbidities, and have a shorter duration of mechanical ventilation are also more likely to experience weaning success.
Weaning Failure
Weaning failure is defined as the failure of a spontaneous breathing trial (SBT) or the need for reintubation within 48 hours of being removed from mechanical ventilation.
The longer the patient is on the ventilator, the greater the risk of weaning failure. Patients with a chronic disease, such as COPD, are more likely to experience weaning failure than those with an acute illness, such as a surgical procedure.
Conditions That Can Complicate Weaning
There are several pathophysiologic, cardiac, and dietary conditions that can hinder a successful weaning outcome. Some examples include:
- Fever
- Infections
- Renal failure
- Sepsis
- Sleep deprivation
- Hypertension
- Hypotension
- Fluid imbalance
- Anemia
- Caloric deficit
- Acid-base imbalance
- Electrolyte imbalance
Patients with chronic lung diseases are also at an increased risk of weaning failure.
Weaning Criteria
When assessing a patient’s readiness to wean from mechanical ventilation, there are some criteria that must be met, including the following:
- Adequate cough
- Adequate secretions
- Hemodynamic stability
- Arterial blood gas (ABG)
- Rate (f)
- Tidal volume (VT)
- Vital capacity (VC)
- Minute ventilation (MV)
- MIP/NIF
- Maximum expiratory pressure (MEP)
- Rapid shallow breathing index (f/VT)
- PaO2
- SaO2
- PaO2/FiO2 (P/F)
- Qs/Qt
- P(A-a)O2
- Static compliance
- Airway resistance
- VD/VT
- Spontaneous breathing trial (SBT)
The first step for considering weaning requires resolution of the acute phase of the disease that caused mechanical ventilation.
The patient must also have an adequate cough with manageable secretions while showing signs of hemodynamic stability. If these criteria are met, then you can move along to the others that are listed.
Ventilator Weaning Practice Questions:
1. What is the definition of weaning success?
The absence of ventilatory support 48 hours following extubation.
2. What is weaning in progress?
Patient’s are extubated but still get ventilatory support via noninvasive ventilation.
3. What is weaning failure?
Either failure of the spontaneous breathing trial, or the need for reintubation within 48 hours following extubation.
4.
Tachypnea, Tachycardia, Hypertension, Hypotension, Hypoxemia, Acidosis, and Arrhythmias.
5. Regarding the patient’s condition, what should be considered before weaning?
The patient should have recovered from the acute phase of the disease that led to mechanical ventilation AND
6. What are the conditions that may hinder a successful weaning outcome?
Patient/Pathophysiologic, fever, infection, renal failure, sepsis, sleep deprivation, cardiac/circulatory, arrhythmias, blood pressure (high/low), cardiac output (high/low), fluid imbalance, anemia, dysfunctional hemoglobins, dietary/acid-base/electrolytes, nutritional or caloric deficit, acid-base imbalance, and electrolytes imbalance.
7. What is the Rapid Shallow Breathing Index (RSBI)?
It is used to evaluate the effectiveness of spontaneous breathing.
8. What is a Spontaneous Breathing Trial (SBT)?
It helps to evaluate a patient’s readiness to be weaned from the ventilator and extubated. It can be augmented with low-level pressure support, CPAP, or ATC and may last up to 30 minutes.
9. How to wean with SIMV?
Reduce the SIMV frequency by two breaths/min. Monitor the SpO2 and get ABG results as needed. Reduce the SIMV frequency until it reaches two breaths/min. This may take hours for healthy patients or multiple days for patients with abnormal functions.
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10. How is weaning with PSV performed?
Start the PS level at 5 to 15 cm H2O and adjust it gradually (up to 40 mm H2O) until a desired spontaneous tidal volume (10 to 15 mL/kg) or spontaneous frequency (less than or equal to /min) is obtained.
11. What
A PaO2 less than or equal to 60 mm Hg on
12. What is the Weaning Protocol?
Is there evidence that the underlying cause will return? Is there sufficient inspiratory effort? Are they hemodynamically stable? Is oxygenation and acid-base status adequate? (p/f ratio greater than 150 mm Hg, PEEP less than 8 cm H2O and pH greater than or equal to 7.25) Is sedation light or off completely? (can the patient make eye contact to voice command)
13. What are some early signs of weaning failure?
Tachypnea, Use of accessory muscles, Dyspnea, Chest Pain, Diaphoresis, and Chest-Abdomen asynchrony.
14. What is weaning failure is generally related to?
Airway resistance, Decreased compliance, or Muscle fatigue.
15. To reduce airway resistance, what size ET tube should be used?
Size 8 or larger
16. What are the conditions that decrease static compliance?
Atelectasis, ARDS, Tension pneumothorax, Obesity, and Retained lung secretions.
17. What are the conditions that decrease dynamic compliance?
Bronchospasm, Kinking of ET tube, Airway obstruction, and Retained lung secretions
18. What is terminal weaning?
It is the withdrawal of mechanical ventilation that results in the death of the patient. It is applied when the patient’s condition is worsening or the ventilator has maxed out on what it can do for the patient.
19. What is weaning?
It is a process of gradually reducing mechanical ventilatory support until a patient is able to assume sustainable spontaneous breathing.
20. The absence of ventilatory support for at least 48 hours following extubation is known as what?
Weaning success.
21. What are the reasons for re-intubation?
Hypoventilation/ hypercapnia, respiratory acidosis, rapid shallow breathing, excessive secretions, and respiratory muscle atrophy.
22. Before weaning, the patient should have recovered from what?
The acute phase of the disease.
23. What are some patient or pathophysiologic conditions that may hinder a successful weaning outcome?
Fever, infection, renal failure, sepsis, and sleep deprivation.
24. What are some cardiac or circulatory conditions that may hinder a successful weaning outcome?
Arrhythmias, high or low blood pressure or cardiac output, fluid imbalance, anemia, dysfunctional hemoglobin.
25. What are some dietary/acid-base/electrolyte imbalances that may hinder a successful weaning outcome?
A nutritional or caloric defect, acid-base imbalance, electrolytes imbalance.
26. What is the clinical criteria for weaning?
The resolution of the acute phase of the disease, a good cough, absence of excessive secretions, and cardiovascular and hemodynamic stability.
27. A successful spontaneous breathing trial lasts how long?
20 to 30 minutes.
28. What type of epinephrine is used to treat airway edema following extubation?
Racemic
29. What is the area of edema that may occur after the ET tube is removed?
Subglottic edema.
30. What mode of ventilation is designed to make automatic adjustments from the time ventilation is initiated until ventilation can be discontinued?
ASV
31. What is a trial of sustained breathing without mechanical support?
SBT
32. What is the term for the placement of an ET tube following the recent removal of it?
Reintubation
33. What is known as the removal of the ET tube?
Extubation
34. What type of spasm that may occur after the ET tube is removed?
Laryngospasm
35. Describe weaning?
It is the gradual reduction of ventilatory support from a patient who is improving.
36. What are some scenarios in which patients typically do not require a slow withdrawal process from mechanical ventilation?
Recovery from anesthesia, treatment of uncomplicated drug overdose, and exacerbations of asthma.
37. What are 3 potential consequences that may be avoided by discontinuing mechanical ventilation?
VAPS, airway trauma from the ET tube, and unnecessary sedation.
38. What are some potential hazards associated with the premature withdrawal of ventilatory support or of the airway?
Ventilatory muscle fatigue, compromised gas exchange, and loss of airway protection
39. What 3 approaches are commonly used to reduce ventilatory support?
SIMV, CPAP, and T-piece
40. What are some of the more sophisticated closed-loop modes that are used for weaning patient?
Volume-targeted, PSV, auto-mode, MMV, ATC, and artificial intelligence systems.
41. What should be the primary factor in determining whether a patient is ready to be weaned from mechanical ventilation?
The patient’s level of recovery from the condition that imposed the need for mechanical ventilation and the patient’s overall clinical condition and psychological state.
42. What is the underlying theory of IMV that helps facilitate weaning a patient from mechanical ventilation?
The patient’s respiratory muscles work during spontaneous breathing intervals and rest during mandatory mechanical breaths.
43. Why is pressure support added during IMV?
It is added to reduce the patient’s WOB during spontaneous breaths and prevent fatigue.
44. What are the trigger, limit, and cycle variables for PSV?
Patient triggered, pressure limited, and flow cycled.
45. What parameters are within the patient’s control during PSV?
The patient controls the rate, inspiratory time, and depth of each breath.
46. What is the most practical method of establishing the level of PSV?
Base the initial PSV on the patient’s measured airway resistance.
47. What is considered acceptable ranges for the tidal volume and respiratory rate for a patient receiving PSV?
A respiratory rate of 15-25 breaths/min and a VT of 300-600 mL.
48. What are 4 signs or symptoms that would indicate an inappropriately set pressure support level?
Tachycardia, hypertension, tachypnea, diaphoresis, paradoxical breathing, respiratory alternans, and excessive accessory muscle use.
49. What is the major disadvantage of T-piece weaning?
It requires a high level of staff attention.
50. What mode of mechanical ventilation can be used as a substitute for T-piece weaning?
CPAP
51. What is the major advantage of using CPAP instead of a T-piece trial?
CPAP provides continuous monitoring of the patient and backup ventilator modes in case of apnea.
52. What weaning mode allows spontaneous breathing between mechanical breaths?
SIMV
53. What weaning mode is similar to a T-piece with alarm support capability?
CPAP
54. What weaning mode compensates for increased resistance and WOB through an ET?
ATC
55. What weaning mode adjusts to various levels of support automatically?
Automode
56. What weaning mode provides pressure-limited breaths that target a volume and rate?
PSV
57. What weaning mode maintains a consistent minimum minute ventilation?
MMV
58. What weaning mode delivers a set tidal volume in a pressure mode of ventilation?
VS
59. What are the (3) clinical criteria for weaning?
(1) The problem that caused the patient to require ventilation must have been resolved. (2) Certain measurable criteria should be assessed to help establish a patient’s readiness for discontinuation of ventilation. (3) A spontaneous breathing trial should be performed to firmly establish readiness to wean.
60. What are the (4) physiological factors that may adversely affect the weaning process?
Fear, anxiety, delirium, and ICU psychosis.
61. 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?
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.
62. What is the procedure for a cuff leak test?
The patient is disconnected from the ventilator, the cuff is deflated, and the ET tube or tracheostomy tube is obstructed.
63. In a cuff leak test, what does the measured volume that escapes from around a deflated cuff indicate?
A leak of less than 110 mL may indicate the presence of subglottic edema and a high risk of post-extubation stridor.
64. Why is vital capacity not considered a good indicator for the discontinuing of ventilator support?
Because the test requires the patient’s cooperation, which is not always consistent.
65. What parameter is a primary index of the inspiratory drive of a breath?
Airway occlusion pressure (P0.1 or P100)
66. What index is used to assess the potential for respiratory muscle overload and fatigue?
CROP index
67. What are the (4) components that the CROP index measures?
(1) Compliance, (2) Respiratory rate, (3) Oxygenation, (4) Inspiratory pressure.
68. How long must a patient tolerate an SBT to be considered ready for ventilator discontinuation and extubation?
30-120 minutes
69. What is the formula for RSBI?
The RSBI is calculated by dividing the respiratory frequency (breaths/min) by the tidal volume in liters.
69. What values of an RSBI indicate that weaning may be successful?
Values less than 105 (range, 60-105) indicate that successful weaning is more likely.
70. What are the (2) criteria that must be met before a decision can be made to remove an artificial airway?
(1) Patient’s ability to protect the airway and (2) airway patency.
71. What are the (4) factors that indicate that extubation is likely to be successful?
(1) Ability to mobilize secretions, (2) has a peritubular leak on cuff deflation, (3) has a strong cough, and (4) no excessive secretions.
72. What are the (3) clinical patient conditions in which an artificial airway should not be removed after weaning from mechanical ventilation?
(1) Upper airway burns, (2) a weak cough, and (3) large amounts of secretions.
73. What are (3) complications associated with prolonged intubation?
VAP, VILI, and damage to the airway.
74. How does the administration of heliox aid in the treatment of partial airway obstruction and stridor caused by post-extubation glottic edema?
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.
75. How is heliox therapy administered in this situation?
Via a nonrebreathing mask.
76. What are the factors that increase the risk of aspiration after extubation?
(a) Use of muscle relaxants, (b) presence of a gastric tube, (c) presence of abnormal
77. What is the primary indication for NIV after extubation?
Patients who no longer need an artificial airway but require additional ventilatory support after extubation.
78. What are the benefits of using NIV after extubation?
(a) Improves survival, lowers mortality rate; (b) reduces the risk of nosocomial pneumonia; (c) lowers the incidence of septic shock; and (d) shortens the length of ICU and (e) hospital stays
79. What are the advantages of therapist-driven protocols for both patients and hospital staff?
It helps to shorten the time required for ventilatory support, resulting in a lower rate of extubation failures, which helps reduce hospital costs.
80. What are the clinical characteristics of patients that may benefit from a trach tube placement?
Patients who require high levels of sedation to tolerate ET tubes; those who have marginal respiratory mechanics; those who may gain psychological benefit from the ability to eat orally, communicate by speech, and experience greater mobility; and those whose increased mobility may aid physical therapy efforts.
81. What are the beneficial outcomes for performing a trach?
(a) Less facial discomfort, (b) decreased WOB, (c) less dead space, (d) better removal of secretions, and (e) opportunity for oral feeding.
82. What alternative sites are available for patients who are medically stable yet still require mechanical ventilation following multiple failed weaning attempts in the ICU?
Regional weaning centers, noninvasive respiratory care units, long-term acute care facilities, extended care facilities, long-term ventilator units in acute care hospitals, and home.
83. In the assessment of a patient’s respiratory rate, which of the following values would indicate the highest probability that the patient will likely be able to maintain spontaneous ventilation?
A respiratory rate of less than 25 bpm.
84. Which of the following drugs is used most often to treat post-extubation glottic edema?
Racemic epinephrine.
85. Which of the following is the
-20 to -30
86. 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
No assistance is required.
87. What should be required before an SBT?
The patient should be able to maintain an adequate PaO2 and PaCO2. The patient should be hemodynamically stable.
88. Which of the following patient conditions is the LEAST important consideration prior to weaning a patient from mechanical ventilation?
The use of positive end-expiratory pressure (PEEP).
89. A mechanically ventilated patient that is recovering from drug overdose has a PaO2 of 76 mmHg on 30% oxygen. What is the PaO2/FIO2 (P/F) index? Is the P/F index normal based on the oxygenation criteria for weaning?
The PaO2/FiO2 index is 253, and yes, it is normal.
90. Partial ventilator support via SIMV is done by reducing the ventilator frequency how?
Reducing it gradually.
91. According to the weaning protocol for mechanical ventilation, the time limit for a spontaneous breathing trial should be up to how long unless terminated earlier?
30 minutes.
92. What is terminal weaning?
Terminal weaning is defined as the withdrawal of mechanical ventilation that results in the death of a patient.
93. Define weaning?
It is the process of gradually withdrawing mechanical ventilatory support and transferring the WOB from the ventilator to the patient.
94. What is the definition of weaning success?
The absence of ventilatory support for at least 48 hours following extubation or decannulation. It is highly variable because of different clinical and patient conditions. It is higher in uncomplicated post-anesthesia recovery. It is lower in medical conditions because of the chronic nature of diseases and the presence of coexisting medical problems.
95. What is the definition of weaning failure?
It is the failure of a spontaneous breathing trial or the need for reintubation within 48 hours following extubation.
96. What is an SBT?
It stands for Spontaneous Breathing Trial. It is an evaluation of a patient’s readiness for weaning from mechanical ventilation and extubation. It may be augmented with low levels of pressure support, CPAP, or automatic tube compensation. It may last up to 30 minutes.
97. What are the steps of an SBT?
(1) You may use T-tube, CPAP, or automatic tube compensation, (2) Let the patient breathe spontaneously for up to 30 minutes, (3) You may use low level pressure support (up to 8 cm H20 for adults – up to 10 cm H2O for peds – to augment spontaneous breathing), (4) assess the patient, (5) If the patient tolerates step 4, consider extubation when blood gases and vital signs are satisfactory – return the patient to mechanical ventilation to rest if necessary.
98. What patients can usually handle abrupt weaning?
Patients who have been on the ventilator for a relatively short period of time (1-2 days). Patients who have regained normal cardiopulmonary function. Patients recovering from post-anesthesia, drug overdose, and status asthmaticus.
99. What is extubation?
Simply put, it is the removal of the endotracheal tube.
100. What is decannulation?
Simply put, it is the removal of a tracheostomy tube.
101. Weaning success is defined as what?
Effective spontaneous breathing without any mechanical assistance for 24 hours.
102. What must you know about ICU patients in regards to weaning?
They often have coexisting problems and usually take more time to complete weaning than surgical patients.
103. What is something to keep in mind about vital capacity?
It is effort dependent and requires proper teaching and coaching for accurate measurements.
104. For successful weaning outcomes, the QS/QT should be what?
It should be less than 20% (pulmonary shunt).
105. What are the basic methods for discontinuing ventilatory support?
Increasing periods of spontaneous breathing, IMV or SIMV, PSV, and single daily spontaneous breathing trials (SBTs).
106. Are SBTs and PSV are more effective than other methods of weaning?
Yes, yes they are.
107. What is the simple definition of weaning?
The gradual reduction in the level of ventilatory support.
108. What is the definition of discontinuing ventilatory support?
The overall process of removing the patient from the ventilator regardless of the method used.
109. The ventilator work load refers to what?
The demand of the ventilatory muscles.
110. The ventilator work load is determined by what?
The level of ventilation needed, the compliance of the lungs and thorax, the resistance to flow in the airways, and the imposed work of breathing.
111. An increased demand and level of ventilation required is determined by what?
Metabolic rate (sepsis), CNS drive, and Ventilatory deadspace.
112. Respiratory muscle strength is influenced by what?
The patient’s age, sex, muscle bulk, and overall health.
113. Controlled ventilation can lead to what?
Ventilation muscle atrophy.
114. Once the ventilatory muscles fatigue, they must be?
The must be rested for 24 hours to recover.
115. What are the factors considered for successful weaning?
Ventilatory workload vs capacity, Oxygenation status, Cardiovascular status, and Psychological factors.
116. A careful patient evaluation is required to determine what?
Which patients are ready to be removed quickly, which may need a prolonged ventilatory phase, and which are not ready for the discontinuation of ventilatory support.
117. Patients receiving support for 72 hours or less?
They often can be removed quickly from the ventilator.
118. Patients who need longer than 72 hours of support?
They may require a more structured approach for weaning.
119. The current guidelines that recommend patients requiring more than 24 hours of mechanical ventilation should be what?
They should be carefully assessed to determine all causes of ventilator dependence.
120. In order to be weaned, patients must be able to initiate what?
Inspiratory effort and breathe spontaneously.
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121. Advantages of adding continuous positive airway pressure (CPAP) to T-tube weaning include?
Improved blood oxygenation, decreased work of breathing, and compensation for auto-PEEP.
122. Advantages of noninvasive positive-pressure ventilation include?
It preserves airway defenses, allows intermittent use, and allows speech or swallowing.
123. What factors will increase ventilatory demand (workload)?
Severe hypoxemia, Pulmonary Infection, and Bronchospasm.
124. What are the common causes for weaning failure?
Myocardial ischemia, critical illness, polyneuropathy, and psychological dependence.
125. What are the advantages of using pressure-supported ventilation for weaning?
Reduced work of breathing, respiratory muscle fatigue prevented, and better patient comfort and synchrony.
126. What are the disadvantages of using intermittent mandatory ventilation for weaning?
A potentially high work of breathing, weaning time possibly prolonged, and patient-ventilator dyssynchrony.
127. What are the disadvantages of using the T-tube method for weaning?
More staff time is required, abrupt transition is sometimes difficult, and the lack of alarm systems.
128. What are the useful strategies in managing the psychological problems encountered in weaning some patients from ventilator support?
Secure a psychiatric consult, decrease environmental stress, and teach relaxation methods.
129. Which drug categories can depress ventilatory drive and hinder weaning?
Analgesics, narcotics, and hypnotics.
130. What factors can reduce a patient’s ventilatory drive?
Respiratory alkalosis, depressant drugs, and decreased metabolism.
131. What indicates that a patient’s renal function is adequate for weaning?
No major weight gain, no edema present, and normal electrolytes needed to be given.
132. Which weaning methods provide the best respiratory muscle strength conditioning?
Pressure-supported ventilation, intermittent mandatory ventilation, and volume-assured pressure support (VAPS).
133. What are the limitations of noninvasive positive-pressure ventilation?
It requires patient cooperation, limits access to the airway, and causes mask-related problems.
134. What are the treatment options for severe post-extubation stridor?
Nebulized racemic epinephrine, nebulized dexamethasone, and heliox mixtures.
135. Ventilatory capacity is determined by what?
Central nervous system (CNS) drive, muscle strength, and muscle endurance.
136. When is ventilator dependence likely to occur?
When arterial hypoxemia is present, when the patient is malnourished, and when the cardiovascular system is unstable.
137. What is good to know about artificial tracheal airways and weaning?
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.
138. Which of the following is true about noninvasive positive-pressure ventilation (NIPPV)?
NIPPV can support ventilation without a tracheal airway. NIPPV should not be used with patients at risk for aspiration. NIPPV can be used to prevent reintubation when weaning fails.
139. While monitoring a patient being weaned through a T-tube protocol, signs indicating that mechanical ventilation should be restored include?
The development of cardiac arrhythmias, asynchronous or paradoxical breathing, and the development of severe hypotension.
Final Thoughts
Weaning a patient from mechanical ventilation is an important aspect of respiratory care. There are many factors that can contribute to weaning success or failure.
Before starting a spontaneous breathing trial (SBT), the patient must meet certain weaning criteria. This allows practitioners to determine the patient’s readiness for weaning. Respiratory therapists are responsible for carrying out this process.
If you found this guide to be helpful, check out our similar article on the initiation of mechanical ventilation. Thanks for reading!
Written by:
John Landry, BS, RRT
John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.
References
- Chang, David. Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013.
- Rrt, Cairo J. PhD. Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 7th ed., Mosby, 2019.
- Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
- “Weaning off Mechanical Ventilation: Much Less an Art, but Not yet a Science.” National Center for Biotechnology Information, U.S. National Library of Medicine, Dec. 2019, www.ncbi.nlm.nih.gov/pmc/articles/PMC6976421.