Ventilator Weaning


Article Author:
Mario Fadila


Article Editor:
Hariharan Regunath


Editors In Chief:
Jon Parham
Abigail Frank
Jon Sivoravong


Managing Editors:
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Frank Smeeks
Kristina Soman-Faulkner
Benjamin Eovaldi
Radia Jamil
Sobhan Daneshfar
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Hajira Basit
Phillip Hynes


Updated:
12/2/2018 12:40:48 AM

Introduction

 Mechanical ventilation is an established supportive treatment for patients with various forms of respiratory failure. Despite the widespread use and clear benefits of mechanical ventilation, it is not a risk-free intervention. Prolonged mechanical ventilation increases the risk of pneumonia, barotrauma, tracheal injuries and musculoskeletal deconditioning. At the same time, delayed weaning is associated with increased morbidity, mortality, hospital stay and risk of long-term care facility discharge. [1][2][1]

For the majority of patients (70%), weaning from mechanical ventilation is a simple and straightforward process. That usually entails extubation after the passage of first spontaneous breathing trial. The remaining 30% of patients represent a challenge for ICU physicians. Difficulties usually arise in patients with chronic obstructive and restrictive pulmonary disease, heart failure, neuromuscular disorders among other potential causes. In our discussion, we review the most common barriers to successful ventilator weaning and the various extubation readiness assessment tools. [3][4][5][3]

Etiology

Respiratory Insufficiency

Arguably the most common mechanism underlying failure to wean patients off the ventilator. In its simplest form, the problem stems from an imbalance between respiratory pump capacity and demands.

Reduced Ventilatory Capacity  

Prolonged duration of mechanical ventilation, especially when accompanied by the use of passive modes of ventilation can lead to diaphragmatic weakness and atrophy. Other factors that contribute to respiratory muscle weakness include excessive steroids, sedatives, and paralytics use, critical illness myopathy, a systemic inflammatory response associated with sepsis, malnutrition, and immobility. All of these factors are inherent to the ICU patient population; together they trap the patient in a vicious circle where more weakness leads to more difficulty to wean off the vent, leading to prolonged ICU stay and so forth.

Cardiovascular Insufficiency

Heart failure is another risk factor that can compound the process of ventilator weaning. Important physiological changes occur during the process of transition from mechanical ventilation to spontaneous breathing. The most notable of which is a loss of positive intra-thoracic pressure. That results in an increase in venous return to the right ventricle and increase in both preload and afterload. This is particularly relevant in the ICU patient population, most of whom have variable degrees of positive fluid balance. That increase in cardiac work can raise myocardial oxygen demand and precipitate ischemia in patients with coronary artery disease. 

Evaluation

Examining Readiness to Wean From Mechanical Ventilation

Despite the known hazards associated with prolonged mechanical ventilation, many patients remain unnecessarily intubated for longer periods than needed. This knowledge stems from the fact that patients who accidentally self-extubate have 31-78% risk of reintubation. That means the same patient population has 22-69% chance of successfully weaning off mechanical ventilation. Even the most experienced clinicians may underestimate a patient’s readiness for ventilator weaning.

It is for this reason that major critical care societies strongly encourage the implementation of protocols for daily sedation interruption and spontaneous breathing trials. However, before a patient is considered for ventilator weaning, the following questions are a well worth consideration to ensure maximum chances of successful ventilator weaning:

  • Has the disease process that led to mechanical ventilation resolved or improved?
  • Is the patient hemodynamically stable? Absence of shock or requirement for pressors or significant arrhythmias
  • Is patient adequately oxygenated? (Fraction of inspired oxygen <50% and/or low PEEP requirements)
  • Is patient adequately awake and communicative? (absence of encephalopathy, agitation or overtly altered mental status)

Note that presence of any of the above parameters doesn’t guarantee weaning failure. The opposite also holds true. Because clinical judgment may sometimes over or underestimate patient’s readiness, a need for objective measures exists. Those indices should ideally be easily measurable and widely applicable.

Some of the suggested indices correlate directly with ventilatory parameters, such as the minute ventilation (VE) or vital capacity(VC). Other indices correlate with the degree of oxygen requirements such as the ratio of arterial to alveolar oxygen ratio (Pao2/PAo2), the ratio of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) ratio or the alveolar-arterial oxygen gradient (A-a gradient). Also, some parameters examine the respiratory muscle strength, such as the maximal inspiratory pressure (MIP).

The reason there are so many indices is that none of them is perfect. There is a wide degree of variability in the performance of the above tests, and their predictive value is far from optimal. The reason being is that these indices only measure one aspect of the respiratory function, while the weaning process is complex and multifactorial.

Rapid Shallow Breathing Index (RSBI)

Defined as the ratio of respiratory rate (f) to tidal volume (VT), initially described by Yang and Tobin 1991. In their trial, they found that RSBI <105 correlated with weaning success, while a score >105 correlated with weaning failure. The reported sensitivity, specificity, positive predictive value and negative predictive values were  97, 64, 78, and 95 percent, respectively. Since the initial description, their results were confirmed in multiple subsequent trials, and their test has gained wide popularity and is integrated into ventilator liberation protocols in many ICUs.The test is ideally conducted over 30 minutes period while the patient is on minimal pressure support ventilation (PSV) and/or small PEEP value. 

Treatment / Management

Spontaneous Breathing Trial (SBT)

Patients should be assessed daily for readiness to wean off mechanical ventilation. Trials are often part of an ICU protocol for ventilator liberation, and usually, start after patient fulfills many of the criteria mentioned previously.

Trials should be conducted with patient off sedation, on minimal ventilator support (pressure support ventilation PSV of 5-8 mmHg or less and/or a small amount of PEEP. There is some data to suggest using zero PSV and zero PEEP (known as ZEEP trials), which seems to correlate with higher chances of successful ventilator weaning.

For a spontaneous breathing trial to be considered successful, a patient should be able to breathe for at least 30 minutes without signs of hemodynamic derangement (respiratory rate <35, no significant elevation or drop in blood pressure, oxygen saturation >90%), and with the absence of signs of distress or anxiety. a is usually combined with one of the readiness indices such as the RSBI calculated at the beginning and end of each trial. Other factors to consider include respiratory secretions burden, the presence of a strong cough, and ability to maintain adequate wakefulness. A successful trial is usually followed by removal of the endotracheal tube and discontinuation of mechanical ventilation. Failure to fulfill one or more of the aforementioned parameters usually correlate with higher chances of weaning failure and reintubation. Those patients should be placed back on comfortably, controlled mode with appropriate sedation. A careful work-up should be done to examine underlying barriers to a successful weaning process.

It is worth to mention that clinician’s judgment is an important consideration when considering extubation. An experienced clinician is often able to combine all the data together and see through an apparently failed weaning parameter.

Extubation to Non-invasive Ventilation (NIV)

Although previously thought of as a failed weaning attempt, it is currently endorsed by American College of Chest Physicians (CHEST) and American Thoracic Society (ATS) to extubate patient to preventive non-invasive ventilation. Multiple studies correlated extubation to NIV with shorter ICU length of stay and short-term mortality. Patients who should be considered for such intervention include high risk intubated patients, including those who repeatedly fail their SBT, patients with advanced COPD or CHF, hypercapnic patients and those >65 years of age. 

Enhancing Healthcare Team Outcomes

A multidisciplinary approach to weaning

Weaning off mechanical ventilation can often become a daunting task for the clinician caring for critically ill patients. It requires a meticulous daily assessment and collaborative effort between the ICU care team. The ultimate decision should be based on a multitude of clinical factors, combined with predictive scores after careful clinician assessment that often influenced by experience. It is vital to work as a team that includes a pulmonologist, intensivist, anesthesiologist, respiratory therapist, and an ICU when it comes to weaning. No one person should make the decision to wean a patient; there are countless cases of solo weaning cases gone bad. Every weaning that fails is associated with a higher morbidity for the patient. It is important to know and understand that at any given moment, there are more mechanically ventilated patients than should be. Finally, weaning from a mechanical ventilator should never be an emergency and preferably should be done during the day time.[6][7]


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Ventilator Weaning - Questions

Take a quiz of the questions on this article.

Take Quiz
Which of the following statements best describes the role of the rapid shallow breathing index (RSBI) in assessing extubation readiness among mechanically ventilated patients?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following factors is associated with an increased risk of extubation failure among patients who have passed a spontaneous breathing trial?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is not a risk factor for post-extubation stridor?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is the correct definition of “difficult-to-wean” patient?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is not one of the readiness criteria for considering extubation?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Ventilator Weaning - References

References

Wawrzeniak IC,Regina Rios Vieira S,Almeida Victorino J, Weaning from Mechanical Ventilation in ARDS: Aspects to Think about for Better Understanding, Evaluation, and Management. BioMed research international. 2018     [PubMed]
Yeung J,Couper K,Ryan EG,Gates S,Hart N,Perkins GD, Non-invasive ventilation as a strategy for weaning from invasive mechanical ventilation: a systematic review and Bayesian meta-analysis. Intensive care medicine. 2018 Oct 31     [PubMed]
Perkins GD,Mistry D,Gates S,Gao F,Snelson C,Hart N,Camporota L,Varley J,Carle C,Paramasivam E,Hoddell B,McAuley DF,Walsh TS,Blackwood B,Rose L,Lamb SE,Petrou S,Young D,Lall R, Effect of Protocolized Weaning With Early Extubation to Noninvasive Ventilation vs Invasive Weaning on Time to Liberation From Mechanical Ventilation Among Patients With Respiratory Failure: The Breathe Randomized Clinical Trial. JAMA. 2018 Oct 22     [PubMed]
Jung YT,Kim MJ,Lee JG,Lee SH, Predictors of early weaning failure from mechanical ventilation in critically ill patients after emergency gastrointestinal surgery: A retrospective study. Medicine. 2018 Oct     [PubMed]
Obi ON,Mazer M,Bangley C,Kassabo Z,Saadah K,Trainor W,Stephens K,Rice PL,Shaw R, Obesity and Weaning from Mechanical Ventilation-An Exploratory Study. Clinical medicine insights. Circulatory, respiratory and pulmonary medicine. 2018     [PubMed]
Burns KEA,Raptis S,Nisenbaum R,Rizvi L,Jones A,Bakshi J,Tan W,Meret A,Cook DJ,Lellouche F,Epstein SK,Gattas D,Kapadia FN,Villar J,Brochard L,Lessard MR,Meade MO, International Practice Variation in Weaning Critically Ill Adults from Invasive Mechanical Ventilation. Annals of the American Thoracic Society. 2018 Apr     [PubMed]
Borges LGA,Savi A,Teixeira C,de Oliveira RP,De Camillis MLF,Wickert R,Brodt SFM,Tonietto TF,Cremonese R,da Silva LS,Gehm F,Oliveira ES,Barth JHD,Macari JG,de Barros CD,Vieira SRR, Mechanical ventilation weaning protocol improves medical adherence and results. Journal of critical care. 2017 Oct     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Family Medicine. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Family Medicine, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Family Medicine, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Family Medicine. When it is time for the Family Medicine board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Family Medicine.