Ventilator Weaning: Overview and Practice Questions (2024)

by | Updated: Apr 19, 2024

Ventilator weaning is a critical aspect of patient care in intensive care units (ICUs) and other medical settings where mechanical ventilation is utilized.

It refers to the process of gradually reducing and ultimately discontinuing ventilator support once a patient’s respiratory function improves sufficiently to sustain spontaneous breathing.

Effective ventilator weaning requires careful monitoring, assessment, and management to ensure patient safety and optimize outcomes.

This article provides an overview of ventilator weaning, highlighting key principles, strategies, and considerations involved in this essential aspect of critical care medicine.

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What is Ventilator Weaning?

Ventilator weaning is the process of gradually decreasing ventilator support to enable a patient to resume breathing independently. This critical step in recovery involves careful monitoring and adjustments to ensure the patient’s respiratory system can maintain adequate oxygen and carbon dioxide levels without mechanical assistance.

Weaning patient from mechanical ventilation vector

Weaning Success

Weaning success is achieved when a patient can sustain spontaneous breathing for at least 48 hours after extubation without requiring reintubation.

Factors increasing the likelihood of weaning success include being a surgical patient, being younger, having fewer comorbid conditions, and having a shorter period of dependence on mechanical ventilation.

Weaning Failure

Weaning failure occurs when a patient either cannot complete a spontaneous breathing trial (SBT) successfully or requires reintubation within 48 hours after discontinuation of mechanical ventilation.

The risk of weaning failure escalates with prolonged ventilator use.

Patients with chronic conditions, such as chronic obstructive pulmonary disease (COPD), are at higher risk of weaning failure compared to those recovering from acute conditions or surgical interventions.

Conditions That Can Complicate Weaning

Weaning from mechanical ventilation can be complicated by a range of conditions that impact a patient’s ability to independently maintain effective breathing.

These complications can be grouped into several broad categories, including respiratory, cardiac, neuromuscular, psychological factors, and issues stemming from critical illness or general health status.

Key conditions include:

  • Respiratory Conditions: such as Chronic Obstructive Pulmonary Disease (COPD), asthma, pneumonia, acute respiratory distress syndrome (ARDS), and pulmonary edema, which affect lung function and gas exchange.
  • Cardiac Conditions: including heart failure and coronary artery disease, which can limit oxygen delivery to tissues.
  • Neuromuscular Conditions: like Guillain-Barré Syndrome, Myasthenia Gravis, and Critical Illness Polyneuropathy and Myopathy (CIP/CIM), which impact muscle strength and endurance, crucial for breathing.
  • Psychological Factors: such as anxiety and panic disorders, and depression, which can interfere with the patient’s ability to engage in the weaning process effectively.
  • Critical Illness and Other Factors: including sepsis, malnutrition, and the prolonged use of sedatives and muscle relaxants, which can affect overall strength, organ function, and the patient’s readiness to wean.

Note: Each category represents a significant challenge to the weaning process, necessitating individualized care and strategies to overcome these obstacles.

Weaning Criteria

The criteria for weaning a patient from mechanical ventilation are designed to assess whether a patient is ready to begin the process of discontinuing ventilatory support.

These criteria encompass a range of physiological, clinical, and laboratory parameters that indicate a patient’s ability to sustain spontaneous breathing.

Key weaning criteria include:

  • Adequate cough
  • Manageable secretions
  • Hemodynamic stability
  • Acceptable arterial blood gas (ABG)
  • Rate (f) < 35 breaths/min
  • Tidal volume (VT) ≥ 5 mL/kg
  • Vital capacity (VC) ≥ 10 mL/kg
  • Minute ventilation (MV) < 10 L/min
  • MIP/NIF -20 cmH2O
  • Maximum expiratory pressure (MEP) 40 cmH2O
  • Rapid shallow breathing index (f/VT) < 100
  • PaO2 > 60 mmHg at FiO2 up to 0.4
  • SaO2 > 90% at FiO2 up to 0.4
  • PaO2/FiO2 (P/F) ≥ 150 mmHg
  • Qs/Qt < 20%
  • P(A-a)O2 > 350 mmHg at FiO2 of 1.0
  • Static compliance > 30 mL/cmH2O
  • VD/VT < 60%
  • Spontaneous breathing trial (SBT)

These criteria must be tailored to the individual patient, taking into account their overall health, the reason for mechanical ventilation, and any complications that have arisen during their critical illness.

The weaning process is a complex, multidisciplinary effort that requires careful monitoring and adjustment based on the patient’s response.

Ventilator Weaning Practice Questions

1. What is the definition of ventilator weaning?
It is the process of gradually reducing mechanical ventilatory support until a patient is able to assume sustainable spontaneous breathing.

2. What is the definition of weaning success?
The absence of ventilatory support 48 hours following extubation.

3. What is weaning in progress?
When a patient has been extubated but is still receiving support via noninvasive ventilation.

4. What is weaning failure?
Either failure of the spontaneous breathing trial or the need for reintubation within 48 hours following extubation.

5. Patients who fail a spontaneous breathing trial often exhibit what clinical signs?
Tachypnea, tachycardia, hypertension, hypotension, hypoxemia, acidosis, and arrhythmias.

6. 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 be able to assume adequate spontaneous breathing.

7. What conditions can 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 electrolyte imbalance.

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 several hours for healthy patients or multiple days for patients with abnormal functions.

10. How is weaning with PSV performed?
Start the PS level at 5-15 cmH2O and adjust it gradually (up to 40 cmH2O) until a desired spontaneous tidal volume (10-15 mL/kg) or spontaneous frequency (less than or equal to /min) is obtained.

11. What are the criteria for SBT failure?
PaO2 less than or equal to 60 mmHg on an FiO2 greater than or equal to 50%; SaO2 less than 90% on an FiO2 greater than or equal to 50%; PaCO2 greater than 50 mmHg or an increased PaCO2 greater than 8 mmHg from the baseline SBT; pH less than 7.32 or a decrease in pH greater than or equal to 0.07 from the baseline SBT; f/Vt greater than 100 breaths/min/L; Frequency greater than 35 breaths/min or increased by greater than or equal to 50% from the baseline of the SBT; Heart rate greater than 140 beats/min or increased by greater than or equal to 20% from the baseline of the SBT; Systolic BP greater than 180 mmHg or an increase by greater than or equal to 20% from the baseline of the SBT; and the presence of Arrhythmias is also a sign of SBT failure.

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? Is sedation light or off completely? Can the patient make eye contact to voice commands?

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 generally related to?
Airway resistance, decreased compliance, or respiratory 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 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 the rapid shallow breathing index (RSBI)?
It is used to evaluate the effectiveness of 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 most common 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 cardiovascular or circulatory conditions that may hinder a successful weaning outcome?
Arrhythmias, high or low blood pressure or cardiac output, fluid imbalance, anemia, and 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, and electrolyte imbalance.

26. What are 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 may occur after the ET tube is removed?
Laryngospasm

35. What must you know about ICU patients in regard to weaning?
They often have coexisting problems and usually take more time to complete weaning than surgical patients.

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?
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 required 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 are considered acceptable ranges for the tidal volume and respiratory rate for a patient receiving PSV?
Respiratory rate of 15-25 breaths/min and VT of 300-600 mL.

48. What signs or symptoms 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 tube?
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; and 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 can also lead to a reduced central response to hypoxemia and hypercapnia and 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 discontinuation 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

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

67. What components does the CROP index measure?
Compliance, respiratory rate, oxygenation, 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 RSBI values indicate that weaning may be successful?
Values less than 105 (range, 60-105) indicate that successful weaning is more likely.

70. What criteria must be met before a decision can be made to remove an artificial airway?
The patient’s ability to protect their airway and airway patency.

71. What 4 factors 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 complications are 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, providing 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?
Use of muscle relaxants, presence of a gastric tube, presence of abnormal periglottic sensations, inability to close the glottis mechanically, excessive amounts of secretions, and inability to clear secretions effectively.

77. What is the primary indication for NIV after extubation?
Patients who no longer need an artificial airway but require additional ventilatory support.

78. What are the benefits of using NIV after extubation?
Improves survival, lowers mortality rate, reduces the risk of nosocomial pneumonia, lowers the incidence of septic shock, and shortens the length of ICU and 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 tracheostomy 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 tracheostomy?
Less facial discomfort, decreased WOB, less dead space, better removal of secretions, and 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 the patient’s 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 breaths/min.

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 minimal acceptable range for maximal inspiratory pressure when assessing ventilatory muscle strength ?
-20 to -30

86. What should be required before an SBT?
The patient should be able to maintain adequate PaO2 and PaCO2 and be hemodynamically stable.

87. 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).

88. A mechanically ventilated patient who is recovering from a drug overdose has a PaO2 of 76 mmHg on 30% oxygen. What is their PaO2/FIO2 index, and is it normal based on the oxygenation criteria for weaning?
Their PaO2/FiO2 index is 253, and yes, it is normal.

89. Partial ventilator support via SIMV is done by reducing the ventilator frequency how?
Reducing it gradually.

90. 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

91. When weaning success more likely?
Uncomplicated post-anesthesia recovery.

92. 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 cmH20 for adults; up to 10 cmH2O 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; and 6) Return the patient to mechanical ventilation to rest if necessary.

93. What patients can usually handle abrupt weaning?
Patients who have been on the ventilator for a relatively short period of time (i.e., 1-2 days), patients who have regained normal cardiopulmonary function, and patients recovering from post-anesthesia, drug overdose, and status asthmaticus.

94. What is extubation?
The removal of the endotracheal tube.

95. What is decannulation?
The removal of a tracheostomy tube.

96. For successful weaning outcomes, the QS/QT should be what?
It should be less than 20%.

97. 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).

98. Are SBTs and PSV are more effective than other methods of weaning?
Yes, they are more effective.

99. What is a simple definition of weaning?
The gradual reduction in the level of ventilatory support.

100. What is the definition of discontinuing ventilatory support?
The overall process of removing the patient from the ventilator regardless of the method used.

101. The ventilator workload refers to what?
The demand of the ventilatory muscles.

102. The ventilator workload 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.

103. An increased demand and level of ventilation required is determined by what?
Metabolic rate, CNS drive, and ventilator deadspace.

104. Respiratory muscle strength is influenced by what?
The patient’s age, sex, muscle bulk, and overall health.

105. Controlled ventilation can lead to what?
Ventilation muscle atrophy

106. Once the ventilatory muscles fatigue, they must rest for how long?
24 hours

107. What are the factors considered for successful weaning?
Ventilatory workload vs. capacity, oxygenation status, cardiovascular status, and psychological factors.

108. A careful patient evaluation is required to determine what?
Which patients are ready to be removed quickly, which may need prolonged ventilatory support, and which are not ready for the discontinuation.

109. Patients receiving support for 72 hours or less can what?
They often can be removed quickly from the ventilator.

110. Patients who need longer than 72 hours of support require what?
They may require a more structured approach for weaning.

111. 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.

112. In order to be weaned, patients must be able to initiate what?
Inspiratory effort and spontaneous breathing.

113. What are the advantages of adding continuous positive airway pressure (CPAP) to T-tube weaning?
Improved blood oxygenation, decreased work of breathing, and compensation for auto-PEEP.

114. What are the advantages of noninvasive positive-pressure ventilation?
It preserves airway defenses, allows intermittent use, and allows speech or swallowing.

115. What factors will increase ventilatory demand?
Severe hypoxemia, pulmonary infection, and bronchospasm.

116. What are the common causes of weaning failure?
Myocardial ischemia, critical illness, polyneuropathy, and psychological dependence.

117. 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.

118. What are the disadvantages of using intermittent mandatory ventilation for weaning?
A potentially high work of breathing, weaning time is possibly prolonged, and patient-ventilator dyssynchrony.

119. What are the disadvantages of using the T-tube method for weaning?
More staff time is required, abrupt transition is sometimes difficult, and there is a lack of alarm systems.

120. What are the useful strategies for managing the psychological problems encountered in weaning some patients from ventilator support?
Secure a psychiatric consult, decrease environmental stress, and teach relaxation methods.

121. Which drug categories can depress ventilatory drive and hinder weaning?
Analgesics, narcotics, and hypnotics.

122. What factors can reduce a patient’s ventilatory drive?
Respiratory alkalosis, depressant drugs, and decreased metabolism.

123. 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.

124. Which weaning methods provide the best respiratory muscle strength conditioning?
Pressure-supported ventilation, intermittent mandatory ventilation, and volume-assured pressure support (VAPS).

125. What are the limitations of noninvasive positive-pressure ventilation?
It requires patient cooperation, limits access to the airway, and can cause mask-related problems.

126. What are the treatment options for severe post-extubation stridor?
Nebulized racemic epinephrine, nebulized dexamethasone, and heliox mixtures.

127. Ventilatory capacity is determined by what?
Central nervous system (CNS) drive, muscle strength, and muscle endurance.

128. When is ventilator dependence likely to occur?
When arterial hypoxemia is present, when the patient is malnourished, and when the cardiovascular system is unstable.

129. What is good to know about artificial tracheal airways and weaning?
Artificial airways can increase the work of breathing, which increases ventilator dependence.

130. Which of the following is true about noninvasive positive-pressure ventilation (NPPV)?
NIPPV can support ventilation without a tracheal airway, and it should not be used with patients at risk for aspiration. Furthermore, NPPV can be used to prevent reintubation when weaning fails.

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Final Thoughts

Ventilator weaning plays a vital role in the management of critically ill patients requiring mechanical ventilation.

By systematically reducing ventilator support in a safe and timely manner, healthcare providers can facilitate the transition to spontaneous breathing while minimizing complications and promoting recovery.

Although the process requires careful assessment, monitoring, and coordination among multidisciplinary teams, successful ventilator weaning can lead to improved patient outcomes and ultimately contribute to better overall care.

John Landry, BS, RRT

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.
  • Fadila M, Rajasurya V, Regunath H. Ventilator Weaning. [Updated 2022 Dec 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.

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