Comparison of International Consensus Conference guidelines and WIND classification for weaning from mechanical ventilation in Brazilian critically ill patients: A retrospective cohort study.

The knowledge of weaning ventilation period is fundamental to understand the causes and consequences of prolonged weaning. In 2007, an International Consensus Conference (ICC) defined a classification of weaning used worldwide. However, a new definition and classification of weaning (WIND) were suggested in 2017. The objective of this study was to compare the incidence and clinical relevance of weaning according to ICC and WIND classification in an intensive care unit (ICU) and establish which of the classifications fit better for severely ill patients. This study was a retrospective cohort study in an ICU in a tertiary University Hospital. Patient data, such as population characteristics, mechanical ventilation (MV) duration, weaning classification, mortality, SAPS 3, and death probability, were obtained from a medical records database of all patients, who were admitted to ICU between January 2016 and July 2017. Three hundred twenty-seven mechanically ventilated patients were analyzed. Using the ICC classification, 82% of the patients could not be classified, while 10%, 5%, and 3% were allocated in simple, difficult, and prolonged weaning, respectively. When WIND was used, 11%, 6%, 26%, and 57% of the patients were classified into short, difficult, prolonged, and no weaning groups, respectively. Patients without classification were sicker than those that could be classified by ICC. Using WIND, an increase in death probability, MV days, and tracheostomy rate was observed according to weaning difficult. Our results were able to find the clinical relevance of WIND classification, mainly in prolonged, no weaning, and severely ill patients. All mechanically ill patients were classified, even those sicker with tracheostomy and those that could not finish weaning, thereby enabling comparisons among different ICUs. Finally, it seems that the new classification fits better in the ICU routine, especially for more severe and prolonged weaning patients.

Epidemiology of Weaning Outcome according to a New Definition. The WIND Study.

RATIONALE: The weaning process concerns all patients receiving mechanical ventilation. A previous classification into simple, prolonged, and difficult weaning ignored weaning failure and presupposed the use of spontaneous breathing trials. OBJECTIVES: To describe the weaning process, defined as starting with any attempt at separation from mechanical ventilation and its prognosis, according to a new operational classification working for all patients under ventilation. METHODS: This was a multinational prospective multicenter observational study over 3 months of all patients receiving mechanical ventilation in 36 intensive care units, with daily collection of ventilation and weaning modalities. Pragmatic definitions of separation attempt and weaning success allowed us to allocate patients in four groups. MEASUREMENTS AND MAIN RESULTS: A total of 2,729 patients were enrolled. Although half of them could not be classified using the previous definition, 99% entered the groups on the basis of our new definition as follows: 24% never started a weaning process, 57% had a weaning process of less than 24 hours (group 1), 10% had a difficult weaning of more than 1 day and less than 1 week (group 2), and 9% had a prolonged weaning duration of 1 week or more (group 3). Duration of ventilation, intensive care unit stay, and mortality (6, 17, and 29% for the three groups, respectively) all significantly increased from one group to the next. The unadjusted risk of dying was 19% after the first separation attempt and increased to 37% after 10 days. CONCLUSIONS: A new classification allows us to categorize all weaning situations. Every additional day without a weaning success after the first separation attempt increases the risk of dying.

[Weaning from mechanical ventilation. Weaning categories and weaning concepts]. / Entwöhnung von der mechanischen Beatmung. Weaningkategorien und Weaningkonzepte.

The international classification of three weaning categories (simple weaning, difficult weaning, prolonged weaning) has been modified in the German weaning guidelines: the group of prolonged weaning has been subclassified into weaning without noninvasive ventilation (NIV), weaning with NIV, if necessary with continuing NIV in the form of home mechanical ventilation, and weaning failure.Strategies to prevent prolonged weaning comprise daily interruption of sedation, daily screening of capability of spontaneous breathing by a spontaneous breathing trial (SBT) and early implementation of NIV instead of continuing invasive mechanical ventilation especially in hypercapnic patients. The comorbidity left heart failure plays a major role in weaning failure and need for re-intubation-in this case early diagnosis and if necessary modification of heart therapy are important.Specialised weaning-centres offer the option for successful weaning for about 50-60 % of patients declared as unweanable by usual intensive care units. A multimodal therapy concept with respiratory therapists, physiotherapists and speech therapy is necessary to reach this goal. In case of weaning failure a professional discharge management to invasive home mechanical ventilation is important. Competent care by physicians in the out-of-hospital area is restricted by the sectoral division of responsibility by the German health care system. Improvement in this area is urgently needed.

[Weaning--definition and clinical context from the anesthetic point of view]. / Respiratorentwöhnung--Definition und klinischer Kontext aus Sicht der Anästhesie.

Independent from the mode of mechanical ventilation, particularly a quick termination of mechanical ventilation is essential for the weaning progress. Respirator-associated complications need to be early detected and treated. Thus it is important to know correspondent pathomechanisms as they have a crucial influence on the weaning process.To facilitate a holistic treatment approach for patients in prolonged weaning, a tight junction of intensive care within specialized units seems mandatory.

Ventilator discontinuation protocols.

Mechanical ventilation is a life-saving supportive therapy, but it can also cause lung injury, diaphragmatic dysfunction, and lung infection. Ventilator liberation should be attempted as soon as clinically indicated, to minimize morbidity and mortality. The most effective method of liberation follows a systematic approach that includes a daily assessment of weaning readiness, in conjunction with interruption of sedation infusions and spontaneous breathing trials. Protocols and checklists are decision support tools that help ensure consistent application of key elements of evidence-based practice. A majority of studies of weaning protocols applied by non-physician healthcare providers suggest faster weaning and shorter duration of ventilation and ICU stay, and some suggest reduced failed extubation and ventilator-associated pneumonia rates. Checklists can be used to reinforce application of the protocol, or possibly in lieu of one, particularly in environments where the caregiver-to-patient ratio is high and clinicians are well versed in and dedicated to applying evidence-based care. There is support for integrating best-evidence rules for weaning into the mechanical ventilator so that a substantial portion of the weaning process can be automated, which may be most effective in environments with low caregiver-to-patient ratios or those in which it is challenging to consistently apply evidence-based care. This paper reviews evidence for ventilator liberation protocols and discusses issues of implementation and ongoing monitoring.

Predictors of weaning after acute respiratory failure.

Although weaning predictors have been extensively explored in weaning research, their use is currently under debate. From all the stages of mechanical ventilation, the measurements of weaning predictors have been considered by some authors as imperative in order to progress weaning and initiate a weaning trial. However, this practice is rejected by other authors who considered that these tests are not necessary to perform a weaning trial, based in a meta-analysis study from the American College of Chest Physicians. Among all the weaning predictors, the frequency-to-tidal volume ratio (f/VT) remains the most important predictor of weaning. Other predictors have been defined, but their narrow predictive capacity or the requirement of specific technology, have limited their use. The variability of the results obtained by the efficacy of f/VT is probably explained because in most cases weaning is initiated late, when pre-test probability of weaning success is high. In order to reduce weaning duration, weaning strategies must be performed earlier, when a failed weaning trial probably is poor tolerated and the use of f/VT could have a role. New applications of weaning predictors must be clarified in future research, in order to progress in weaning in the context of new studies. Weaning is still a challenging period during mechanical ventilation.

Characteristics and outcomes of ventilated patients according to time to liberation from mechanical ventilation.

RATIONALE: A new classification of patients based on the duration of liberation of mechanical ventilation has been proposed. OBJECTIVES: To analyze outcomes based on the new weaning classification in a cohort of mechanically ventilated patients. METHODS: Secondary analysis included 2,714 patients who were weaned and underwent scheduled extubation from a cohort of 4,968 adult patients mechanically ventilated for more than 12 hours. MEASUREMENTS AND MAIN RESULTS: Patients were classified according to a new weaning classification: 1,502 patients (55%) as simple weaning,1,058 patients (39%) as difficult weaning, and 154 (6%) as prolonged weaning.Variables associated with prolonged weaning(.7d)were: severity at admission (odds ratio [OR] per unit of Simplified Acute Physiology Score II, 1.01; 95% confidence interval [CI], 1.001­1.02), duration of mechanical ventilation before first attempt of weaning (OR per day, 1.10; 95% CI, 1.06­1.13), chronic pulmonary disease other than chronic obstructive pulmonary disease (OR,13.23; 95% CI, 3.44­51.05), pneumonia as the reason to start mechanical ventilation (OR, 1.82; 95% CI, 1.07­3.08), and level of positive end-expiratory pressure applied before weaning (OR per unit,1.09; 95% CI, 1.04­1.14). The prolonged weaning group had a nonsignificant trend toward a higher rate of reintubation (P » 0.08),tracheostomy (P » 0.15), and significantly longer length of stay and higher mortality in the intensive care unit (OR for death, 1.97;95%CI, 1.17­3.31). The adjusted probability of death remained constant until Day 7, at which point it increased to 12.1%.

Clinical relevance of classification according to weaning difficulty.

OBJECTIVE: To evaluate the clinical relevance of the weaning from mechanical ventilation classification system derived from the 2005 international consensus conference, in patients who receive mechanical ventilation for more than 48 hours, and evaluate its correlation with prognosis. METHODS: We conducted a retrospective cohort study in a 12-bed intensive care unit (ICU) in a teaching hospital. We included patients who required > 48 hours of mechanical ventilation and who passed a spontaneous breathing trial (SBT). Weaning and sedation were monitored according to standardized protocol-directed procedures. We collected data on physiological characteristics, mechanical ventilation duration, ICU and hospital stay, and mortality from the medical records database. We assessed one-year mortality with a prospective, standardized method. Multivariate logistic regression was performed to evaluate the association between weaning categories and outcome. RESULTS: We included 329 ventilation episodes, in which 115 patients passed at least one SBT. Thirty-four patients (30%) succeeded in their first SBT (simple weaning group), 47 patients (40%) succeeded in their 2nd or 3rd SBT or in less than 7 days of weaning (the difficult weaning group), and 34 patients (30%) required more than 3 SBTs or more than 7 days of weaning (the prolonged weaning group). There were significant differences in ICU and hospital mortality between the simple, difficult, and prolonged-weaning groups. Prolonged weaning was an independent risk factor for longer ICU stay (odds ratio 15.11, 95% CI 1.61-141.91, P = .01) and hospital mortality (odds ratio 3.66, 95% CI 0.99-13.51). However, the weaning process did not impact one-year mortality (odds ratio 2.61, 95% CI 0.82-8.35). CONCLUSIONS: The new weaning classification system is clinically relevant and correlates to ICU and hospital mortality, but not to one-year mortality.

Incidence and outcome of weaning from mechanical ventilation according to new categories.

Weaning from mechanical ventilation was categorised as simple, difficult or prolonged by an international task force of the American Thoracic Society/European Respiratory Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine/Sociéte de Réanimation de Langue Française in 2007. This new classification has not been tested in clinical practice. The objective of the present study was to determine the incidence and outcome of weaning according to the new categories. We included medical and surgical patients who required mechanical ventilation in a prospective, multicentre, 6-month cohort study. From an initial cohort of 510 patients, 257 intubated patients started weaning. Of these patients, the cumulative incidences of simple, difficult, and prolonged weaning were 152 (59%), 68 (26%) and 37 (14%), respectively. Hospital mortality was increased in patients with prolonged (32%) but not difficult (9%) weaning in comparison with those with simple weaning (13%), overall p = 0.0205. In a multivariate logistic regression model, prolonged but not difficult weaning was associated with an increased risk of death. Ventilator-free days and intensive care unit (ICU)-free days were decreased in both difficult and prolonged weaning. In conclusion, the new weaning category prolonged weaning is associated with increased mortality and morbidity in the ICU. The new category difficult to wean was associated with increased morbidity, but not mortality.

Nonrespiratory predictor of mechanical ventilation dependency in intensive care unit patients.

OBJECTIVE: To determine the role of serum albumin concentration as a predictor of mechanical ventilation dependency. DESIGN: Prospective, observation trial. SETTING: Multidisciplinary intensive care unit (ICU) in a university hospital. PATIENTS: One hundred forty-five consecutive patients who required mechanical ventilation for > 72 hrs. INTERVENTIONS: Patients were classified into five different groups based on the cause of respiratory failure. The following parameters were recorded daily: serum albumin concentration; Acute Physiology and Chronic Health Evaluation II (APACHE II) score; and fluid balance. Using multiple regression, multiple logistic regression analysis, and the Anderson-Gill proportional hazards model, we determined the metabolic factors that could help predict weaning success. MEASUREMENTS AND MAIN RESULTS: The mean length of ICU stay was 12.3 +/- 1.0 days. The duration of mechanical ventilation dependency was 10.5 +/- 1.0 days. The initial mean serum albumin concentration was 25.2 +/- 0.6 g/L. The APACHE II score on the first day of ICU stay was 19.1 +/- 0.6. Although albumin concentration was significantly lower and the APACHE II score was significantly higher in ICU nonsurvivors than in ICU survivors, albumin concentration on ICU admission was not a predictor of the length of time spent receiving mechanical ventilation. The profile of albumin concentration changes was different between weaned and mechanical ventilation-dependent patients. At the time of weaning patients from the ventilator, the median albumin concentration was higher than in those patients who continued to be supported by mechanical ventilation. This effect of albumin could not be attributed to patient fluid balance or to the severity of illness since each factor had an independent influence in predicting weaning, using the Anderson-Gill proportional hazards models. CONCLUSIONS: Initial serum albumin concentration did not necessarily predict weaning success. However, when serum albumin concentration was assessed on a daily basis, its trend was important in determining the relative chance of being successfully weaned from the ventilator. This finding suggests that albumin may be an index of the metabolic status of the patient, which could be important in determining the weanability of the patients who are mechanically ventilated for prolonged periods of time.