ﺑﺎﺯﮔﺸﺖ ﺑﻪ ﺻﻔﺤﻪ ﻗﺒﻠﯽ
خرید پکیج
تعداد آیتم قابل مشاهده باقیمانده : 3 مورد
نسخه الکترونیک
medimedia.ir

Management of the difficult-to-wean adult patient in the intensive care unit

Management of the difficult-to-wean adult patient in the intensive care unit
Author:
Scott K Epstein, MD
Section Editor:
Polly E Parsons, MD
Deputy Editor:
Geraldine Finlay, MD
Literature review current through: Jan 2024.
This topic last updated: Jan 09, 2023.

INTRODUCTION — Many patients in intensive care units (ICUs) are difficult-to-wean off of mechanical ventilation, thereby delaying extubation. The management of patients who are difficult-to-wean in the ICU is reviewed here. Details regarding readiness testing, methods of weaning, and the management of patients who require prolonged mechanical ventilation in long-term care facilities are provided separately. (See "Management and prognosis of patients requiring prolonged mechanical ventilation".)

DEFINITION AND INCIDENCE — Weaning can be classified as simple, difficult, or prolonged [1].

Simple wean – Patients are considered to have undergone a simple wean when they pass their first spontaneous breathing trial (SBT). Approximately half to two-thirds of patients in intensive care units (ICUs) undergo simple weaning, many of which will proceed with extubation. Details regarding what constitutes an SBT and extubation management are discussed separately [2,3]. (See "Initial weaning strategy in mechanically ventilated adults" and "Extubation management in the adult intensive care unit".)

Difficult-to-wean – Patients are considered difficult-to-wean if they fail their first SBT and then require up to three SBTs or seven days to pass an SBT [1]. The incidence ranges from 26 to 39 percent [2,3]. This population mostly includes patients intubated in the first few weeks of acute ICU admission. This population is discussed in this topic review.

Prolonged weaning – Patients are considered to have undergone prolonged weaning if they fail at least three SBTs or require more than seven days to pass an SBT. The incidence ranges from 6 to 14 percent [2,3]. Patients who require more than seven days to wean are at increased risk for death [3] and are also more likely to fail extubation compared with those who undergo simple weaning [4]. While in the ICU, many of these patients are managed similarly to patients who are difficult to wean, many will require tracheostomy and be managed accordingly. (See "Tracheostomy: Rationale, indications, and contraindications" and "Management and prognosis of patients requiring prolonged mechanical ventilation".)

Recognizing that some patients are weaned (or separated) from invasive mechanical ventilation without a well-defined SBT, a modification of the above classification system has been proposed [5]. A "separation attempt" was defined as an SBT (with or without extubation) or extubation (planned or unplanned) without a preceding SBT. Successful separation (or weaning) was defined as extubation within seven days or discharge from the ICU without invasive mechanical ventilation. Among 2907 patients, 24 percent never had attempted weaning or separation, 57 percent had weaning of less than 24 hours (short weaning) with 95 percent success, 10 percent had weaning duration from two to six days (difficult weaning) with 84 percent successful, and in 9 percent weaning to more than one week (prolonged weaning) with 62 percent eventually successful. Importantly, mortality rates rose from one group to the next (short 5 percent, difficult 15 percent, prolonged 30 percent) [5].

IDENTIFY AND CORRECT THE CAUSE — Repeat unsuccessful attempts at weaning usually signify incomplete resolution of the illness that precipitated mechanical ventilation and/or the development of one or more new problems that prevent weaning. The clinician should identify and treat these issues before resuming further weaning trials.

Identify the cause(s) – Numerous factors contribute to failure to wean (table 1) by causing an imbalance between respiratory muscle strength and the work of breathing. Respiratory and cardiac issues are common while psychological, ventilator, or nutrition-related issues are less common. Most of the etiologies are apparent on routine clinical examination, laboratory testing, arterial blood gas analysis, electrocardiography, and chest radiography, as well as an assessment of sedative medications and the ventilator circuit. Additional investigations may be indicated depending upon the suspicion for select etiologies. (See 'Respiratory or ventilatory causes' below and 'Cardiac causes' below and 'Psychological causes' below and 'Ventilator circuit issues' below and 'Nutritional issues' below.)

Treat the cause – When feasible, identified etiologies that contribute to difficult weaning should be treated to improve the probability of successful weaning. As an example, in a series of 12 difficult-to-wean patients who failed weaning due to the development of hypertension during their spontaneous breathing trial (SBT), antihypertensive therapy during the SBT was associated with successful weaning in the majority (92 percent) [6]. In another study of 42 patients who failed weaning, nine of whom were assessed as having heart failure succeeded on a later occasion after diuretic therapy [7].

Resume weaning – Once it is felt that the likely cause of ventilator dependency has been corrected, readiness testing (table 2) should be performed to determine whether weaning can be resumed. (See "Weaning from mechanical ventilation: Readiness testing".)

Respiratory or ventilatory causes — Respiratory/ventilatory causes of failure to wean, their detection and treatment are listed in the table (table 1).

Manifestations are often nonspecific and include tachycardia, tachypnea, respiratory distress, or oxygen desaturation during a breathing trial.

Routine testing including chest, cardiac, and neurologic examination (including an assessment for delirium), complete blood count and chemistries (including calcium, magnesium, and phosphate), chest radiography, arterial blood gas analysis, and nutrition assessment will narrow the differential considerably. Additional testing is individualized and targeted at specific suspected etiologies (eg, computed tomography [CT] of the chest and/or abdomen, CT pulmonary angiography, thoracic ultrasound [lung, pleura, diaphragm, cardiac], nerve conduction studies, bronchoscopy [to look for airway pathology]).

Frequently overlooked causes include:

Auto-positive end-expiratory pressure (PEEP) – The detection and treatment of auto-PEEP are discussed separately. (See "Positive end-expiratory pressure (PEEP)", section on 'Auto (intrinsic) PEEP'.)

Overventilation – A common mistake made is to ventilate patients who have chronic hypercapnia with a minute ventilation that normalizes the arterial carbon dioxide tension (PaCO2). This causes the pH to rise and prompts renal excretion of bicarbonate over three to five days until the pH normalizes. When the patient resumes spontaneous ventilation, such as that during an SBT, an acute respiratory acidosis will result because there is insufficient bicarbonate for buffering (thereby constituting a failed SBT). Thus, patients with chronic hypercapnia should be mechanically ventilated in between SBTs with a minute ventilation that maintains the patient's usual PaCO2.

Imposed work of breathing by endotracheal tubes – Small-sized endotracheal tubes (ETTs) or ETTs narrowed by secretions can significantly increase the work of breathing and produce a pattern of rapid shallow breathing observed in patients with weaning failure (akin to breathing through a straw) [8]. Use of a pressure support SBT may overcome the imposed work of breathing by the ETT, and facilitate successful weaning [9].

Moderate to large pleural effusions are common in ventilated patients at the time of SBTs and in one prospective observational study, were found to be an independent predictor of weaning failure [10]. However, while drainage may improve oxygenation and lung volumes [11] and improve diaphragmatic contractility and respiratory system compliance [12], it has not been conclusively shown to reduce mechanical ventilation days. Thus, we typically avoid large volume thoracentesis in this setting unless indicated for another reason.

Cardiac causes — Weaning-induced myocardial ischemia or cardiac dysfunction (called "weaning-induced pulmonary edema") may contribute to difficult weaning in 20 to 60 percent of patients and when identified, should be treated accordingly (eg, optimize beta-blockade, diuresis) (table 1) [13,14]. Because of the increased work involved in spontaneous breathing, myocardial demand increases, thereby resulting in ischemia in susceptible individuals and pulmonary edema in those with underlying cardiac dysfunction. Ischemia and/or pulmonary edema, in turn, further increase the work of breathing, creating a vicious cycle.

Because PEEP is a treatment for heart failure, weaning-induced cardiac dysfunction may be hard to detect when SBT strategies that include PEEP, rather than a T-tube or non-PEEP strategies, are used [15]. Thus, cardiac dysfunction should be suspected in patients who pass an SBT that included PEEP but who fail extubation and require re-intubation because of acute heart failure.

Manifestations include tachycardia, tachypnea, oxygen desaturation, hypertension or even hypotension during a breathing trial. Patients rarely complain of chest pain, and ST depressions are only occasionally appreciated on a bedside monitor. Risk factors identified in one retrospective study included chronic obstructive pulmonary disease (COPD), previous cardiomyopathy, and obesity [13].

When ischemia is suspected, most experts use continuous multi-lead electrocardiography (EKG) during the SBT, or record an EKG pre- and post-the trial. Rarely, patients require cardiac catheterization for diagnosis. If ischemia is identified, it should be treated. The treatment of myocardial ischemia and cardiac dysfunction are described separately. (See "Overview of the acute management of non-ST-elevation acute coronary syndromes".)

When weaning-induced pulmonary edema is suspected, transthoracic echocardiography is used in conjunction with clinical examination and brain natriuretic peptide (BNP) to justify optimizing cardiac medications and altering fluid management. (See "Treatment and prognosis of heart failure with preserved ejection fraction" and "Overview of the management of heart failure with reduced ejection fraction in adults".)

BNP levels – The possibility that weaning is limited by cardiac dysfunction is suggested by an elevated BNP or N-terminal pro-BNP prior to the weaning trial, an elevated N-terminal pro-BNP at the end of the trial, or a >20 percent increase in BNP during the SBT [7,16-18]. Interventions based upon BNP levels alone are not typically routine. However, one randomized trial reported that BNP-guided fluid management, particularly in patients with left ventricular systolic dysfunction, and reduced time to extubation (59 versus 42 hours) [19].

Echocardiography – The identification of systolic or diastolic dysfunction by transthoracic echocardiography may favor cardiac dysfunction as cause of failure to wean. By finding patients at risk for weaning-induced pulmonary edema [18], transthoracic echocardiography identifies those likely to benefit from treatment for heart failure. As an example, in a study of patients with COPD or heart failure, echocardiography-guided treatment resulted in negative fluid balance and decreased left ventricular filling pressures and weaning success in 12 patients with weaning-induced pulmonary edema [20]. (See "Transthoracic echocardiography: Normal cardiac anatomy and tomographic views".)

While not routine, some echocardiographic parameters and stress echocardiography have been described as potentially useful in identifying weaning-induced cardiac dysfunction. In a meta-analysis of 11 studies, transthoracic echocardiographic parameters indicating decreased left ventricular diastolic function and increased left ventricular filling pressure were associated with weaning failure [21]. In another study of 161 patients mechanically ventilated for cardiogenic shock who were stable and had an ejection fraction of 45 percent, dobutamine stress echocardiography was useful in identifying silent systolic and diastolic dysfunction in patients with weaning failure compared with those who successfully passed an SBT [22].

Other reported methods that require further validation include:

Passive leg raising (PLR) – One study reported that patients who fail to increase cardiac output by >10 percent during PLR (negative PLR test) are significantly more likely to fail an SBT with a pulmonary artery occlusion pressure (PAOP) >18 mmHg at the end of the trial [23]. In another trial, a positive PLR was associated with a successful weaning trial while a negative one was associated with failure [13]. (See "Novel tools for hemodynamic monitoring in critically ill patients with shock", section on 'Passive leg raising or fluid bolus challenge'.)

Others – Other methods include the demonstration of a >5 to 6 percent increase in plasma protein and hemoglobin during an SBT [24] and carbon dioxide rebreathing [25]. Lung ultrasound, by the demonstration of B lines has also been reported to identify pulmonary edema during weaning [26].

Psychological causes — Psychological issues (eg, depression, anxiety, delirium, pain) can be significant impediments to successful weaning. When suspected as contributors to difficult weaning, sedative medications should be adjusted and the psychological issue treated, if feasible (eg, anti-psychotic, anxiolytic, analgesic).

Depression, anxiety, and delirium are common in ventilated individuals. Depressive disorders are present in approximately 40 percent of patients undergoing weaning from prolonged mechanical ventilation and their presence adversely affects weaning success [27]. In another study, patients with delirium were twice as likely to be difficult-to-wean compared with those without delirium [28].

Such disorders may be hard to assess and may simply manifest as agitation, grimacing, disorientation, tachycardia, and hypertension during the trial.

Interventions that may minimize these factors include explaining the weaning plan to the patient, family, and other caretakers; arranging for a trusted caretaker to provide reassurance and explanation during weaning trials; biofeedback (if feasible or available) that displays the breathing pattern [29]; ensuring adequate sleep; and environmental stimulation during the trial, such as television, radio, or books. Efforts to optimize medications for treating delirium, anxiety (eg, switching anxiolytic to dexmedetomidine [30]), and pain should also be performed. Oversedation should be avoided. (See "Sedative-analgesia in ventilated adults: Management strategies, agent selection, monitoring, and withdrawal" and "Sedative-analgesia in ventilated adults: Medication properties, dose regimens, and adverse effects".)

Ventilator circuit issues — Ventilator circuit-related problems can increase the work of breathing and contribute to SBT failure. Potential problems include equipment dead space, poor circuit compliance, low gas compression volume, exhalation valve function, and increased resistance caused by the ETT, inspiratory circuit, or expiratory circuit [31]. Consulting respiratory therapy and examining the pressure and flow tracings on the ventilator screen can help identify and eliminate potential ventilator-related problems. As examples:

An elevated peak inspiratory airway pressure (Ppeak) with a sizeable difference between the Ppeak and plateau pressure (Pplat) may suggest an obstructed ETT or abnormally increased resistance in ventilator circuit tubing (assuming that the patient is on volume cycled ventilation). Examining the ETT and circuit for obstructions or secretions may reveal an obvious source that needs to be treated accordingly (eg, replace ETT or tubing, frequent suctioning, remove the obstruction).

An increase in both Ppeak and Pplat may suggest a malfunction of the exhalation valve, which should be checked if this waveform abnormality is found. However, such changes may also result from issues not related to the ventilator circuit (ie, processes that decrease respiratory system compliance such as pulmonary edema, pneumothorax, pleural effusion).

Ventilator asynchrony may be evident on waveforms. This manifests as minimal or no inspiratory flow, despite patient inspiratory effort due to continued neural inspiration (contraction of inspiratory muscles) after the ventilator has cycled to the expiratory phase (ie, premature opening of the exhalation valve). This may lead to a transient but prominent decrease in peak expiratory flow, followed by increase and then a slow decrease again as neural expiration ends [32]. Such inspiratory effort increases the work of breathing and may injure the inspiratory muscles as they contract eccentrically (eg, the muscle contracts while lengthening). If suspected, the cause of ventilator asynchrony should be sought and treated (eg, auto-PEEP).

Nutritional issues — Protein catabolism induced by critical illness leads to decreased respiratory muscle mass, strength, and endurance, which may lead to difficulty weaning from mechanical ventilation [33]. Sarcopenia (determined by measuring total psoas muscle area by CT) is an independent risk factor for difficulty weaning in surgical patients [34]. Although it is rare for malnutrition to be the sole cause, it can contribute to difficulty weaning such that this population should be evaluated by a nutrition expert and their nutrition support optimized. This approach is based upon studies that report a possible increase in the number of ventilator-free days when adequate nutrition is provided, the details of which are discussed separately. (See "Nutrition support in intubated critically ill adult patients: Initial evaluation and prescription".)

Overfeeding with excessive carbohydrates can impair weaning success [35], presumably by leading to excess carbon dioxide production and an increased ventilatory load on the respiratory muscles. While in the past overfeeding was common, it is now a rare phenomenon.

RESUMING WEANING TRIALS — Once the potential causes have been identified and treated, weaning trials may resume.

General strategies

Posture — Patients should be placed in the posture that they prefer during a weaning trial. For example, patients with diaphragmatic paralysis generally prefer and perform better in an upright position because their vital capacity decreases when they are horizontal. In contrast, patients with intercostal muscle weakness (eg, due to a low cervical cord lesion) may prefer being supine because their lung volumes tend to increase when they move from an upright to a supine position. In patients with chronic obstructive pulmonary disease, the optimal posture varies. Some patients have less dyspnea when they are lying supine, whereas others prefer to lean forward.

Airway management — Airway secretions should be suctioned before every weaning trial.

Theoretically, bronchodilators may facilitate weaning in patients with airway obstruction by reducing airway resistance and the work of breathing [36,37]. In a randomized study, nebulized budesonide reduced weaning duration in chronic obstructive pulmonary disease (COPD) patients who required mechanical ventilation with more than three SBTs or more than seven days from the first SBT [38]. We use short-acting inhaled beta-adrenergic and/or anticholinergic agents prior to a weaning trial in patients with airflow obstruction unrelated to the artificial airway. We use nebulized corticosteroids in difficult-to-wean COPD patients. (See "Invasive mechanical ventilation in acute respiratory failure complicating chronic obstructive pulmonary disease", section on 'Bronchodilators'.)

Trials longer than 30 minutes — In patients who are difficult-to-wean, spontaneous breathing trials (SBTs) are the same as those in patients who are weaning for the first time with one major difference, that trials are longer than the typical 30 minutes in duration (often up to two hours long). Data to support this strategy are discussed separately. (See "Initial weaning strategy in mechanically ventilated adults".)

Importantly, a weaning trial should be terminated early if the patient is failing, since respiratory muscle fatigue may develop and further decrease the chances of successful weaning. Rest is the only treatment for such fatigue, and recovery can take several days.

Method of weaning trial — In our clinical practice, we favor once daily SBTs to wean patients who have failed an initial weaning attempt. We return the patients to a supportive mode of mechanical ventilation after a failed SBT, look for and correct reversible causes of weaning intolerance, and reassess their readiness to wean the next day. We typically use SBT with pressure support (5 to 8 cm H2O) and positive expiratory pressure PEEP; (5 cm H2O) with one exception, that in patients with weaning failure due to cardiac dysfunction, some experts prefer to resume SBTs using a T-tube or pressure support without PEEP; this preference ensures that weaning-induced heart failure is not concealed by the use of PEEP (which is a therapy for heart failure). We do not use intermittent mandatory ventilation weaning. (See "Initial weaning strategy in mechanically ventilated adults", section on 'Choosing a weaning method'.)

A strategy of extubation with immediate application of noninvasive ventilation (NIV) may facilitate earlier extubation in select patients who might otherwise be difficult to wean. While this approach is not necessary as a routine, it is an option for patients who fail the initial SBT and are at risk of failing extubation, including patients with COPD or chronic hypercapnic respiratory failure. This approach should not be used in patients with difficult airways, excessive secretions, or an impaired mental status.

The practice of early extubation to NIV is supported by randomized trials and meta-analyses [39-42]. In a meta-analysis of 16 trials (1156 patients), hospital mortality was lower in the NIV weaning group compared with control (14 versus 20 percent; odds ratio [OR] 0.58, 95% CI 0.29-0.89) [41]. However, the difference was largely accounted for by the large effect size in trials involving patients with COPD (10 versus 20 percent; OR 0.43, 95% CI 0.13-0.81); whereas mortality rates were similar in both groups in trials involving mixed ICU populations (18 versus 20 percent; OR 0.88, 95% CI 0.25-1.48). NIV weaning also reduced mechanical ventilation duration and ICU length of stay, with little to no effect on hospital length of stay. The effect on these outcomes was also largely accounted for by the effect in trials involving patients with COPD, with smaller effect sizes or no effect in trials involving mixed ICU populations. NIV weaning reduced rates of ventilator-associated pneumonia (VAP) both in trials involving patients with COPD and trials in mixed ICU populations (overall VAP rates 10 versus 38 percent; OR 0.22, 95% CI 0.13-0.33). However, VAP definitions varied between trials and many trials had unusually high rates of VAP in the control arm.

One randomized trial of 364 patients with respiratory failure predominantly due to pneumonia or post-surgical complications who were deemed ready to wean, but who had failed a spontaneous breathing trial [40]. Patients were either extubated without passing an SBT and treated with NIV or were extubated only when an SBT was passed. Although the median time to liberation from ventilation (invasive or noninvasive) was no different (4.3 versus 4.5 days), the NIV group, as expected, received fewer days of invasive mechanical ventilation (1 versus 4 days) and had a lower ICU length of stay (10.8 versus 12.2 days). However, despite fewer invasive and total ventilation days, early extubation to NIV had no impact on mortality or rates of reintubation or tracheostomy. Notably, most of the included patients had hypoxemic non-hypercapnic respiratory failure and only 4 percent had an admission diagnosis of COPD or asthma exacerbation. Similarly, in a small randomized study of hypoxemic patients early extubation to NIV reduced the duration of mechanical ventilation and length of hospital stay without reducing mortality [43].

Mechanical ventilation between weaning trials — One hour of rest on ventilatory support after a successful SBT reduces the risk of extubation failure in critically ill patients [44]. Similarly, appropriate ventilatory settings must be used to allow respiratory muscles to rest after a failed weaning trial (between SBTs), where the risk for respiratory muscle fatigue is substantial. In contrast, inappropriate settings can create more work than is required for spontaneous breathing, leading to respiratory muscle fatigue and impairing successful weaning.

Mode, tidal volume, respiratory rate, and/or pressure level – Any mode may be used, as long as the settings (ie, tidal volume, respiratory rate, and/or pressure level) are such that the patient is comfortable and performing minimal work. Reasonable settings are those that result in a respiratory rate between 12 and 20 breaths per minute, a tidal volume between 6 and 8 mL/kg, and a minute volume between 6 and 12 L/min. For those on pressure-controlled ventilation a reasonable goal is a plateau pressure <30 cm H2O (the lower the better). For those on pressure support ventilation (PSV), a pressure of 7 to 15 cm H2O usually achieves these goals. Most patients who undergo weaning have a PEEP between 5 and 8 cm H2O. Importantly, patients who have chronic hypercapnia should receive a minute ventilation that targets their baseline arterial carbon dioxide tension. (See "Overview of initiating invasive mechanical ventilation in adults in the intensive care unit", section on 'Settings' and 'Respiratory or ventilatory causes' above and "Weaning from mechanical ventilation: Readiness testing", section on 'Clinical criteria'.)

Trigger method, trigger sensitivity, and inspiratory flow – A reasonable initial approach is to use flow triggering in patients receiving intermittent mandatory ventilation and in patients receiving PSV who have increased inspiratory effort during triggering. Either pressure or flow triggering is acceptable in other patients. A trigger sensitivity of -1 to -2 cm H2O during pressure triggering or -1 to -2 L/min during flow triggering is appropriate. An initial inspiratory flow rate of 60 L/min reasonable for most patients. The flow rate can be increased to as needed if a patient appears to be struggling. (See "Overview of initiating invasive mechanical ventilation in adults in the intensive care unit", section on 'Flow rate and pattern' and "Overview of initiating invasive mechanical ventilation in adults in the intensive care unit", section on 'Trigger sensitivity'.)

IMPROVING RESPIRATORY MUSCLE STRENGTH — Respiratory muscle weakness is common among mechanically ventilated patients; it may be present at the time of intubation or result from ICU-acquired paresis or ventilator-induced respiratory muscle weakness. As an example, lower diaphragm thickness, measured by ultrasonography within 36 hours of intubation, was associated with prolonged weaning [45]. One study found diaphragm dysfunction, defined by vertical excursion of <10 mm or paradoxical motion during inspiration, in 29 percent of patients ready for weaning. Another study found that 27 percent of patients demonstrated less than a 30 percent increase in diaphragm thickening during inspiration, an indication of dysfunction [46]. Another study reported that 41 percent of patients developed signs of diaphragm atrophy (>10 percent decrease in thickness) by day 4 of mechanical ventilation [47].

Respiratory muscle strength is typically evaluated by clinical examination at the bedside by asking the patient to take a maximal inspiratory effort; weak effort or low lung volumes suggest respiratory muscle weakness. While not routine, more objective bedside measures such as a low negative inspiratory force (eg, <60 cm H2O) and poor diaphragmatic excursion by ultrasound can be used to support clinical findings. Respiratory muscle strength can also be inferred by measurement of handgrip strength using handheld dynamometry [48]. (See "Respiratory muscle weakness due to neuromuscular disease: Clinical manifestations and evaluation" and "Tests of respiratory muscle strength".)

Physical therapy is the mainstay of treatment. Inspiratory muscle strength training (IMST) is of unclear benefit and not routinely used. Importantly, methods that improve muscle strength typically take days to weeks for efficacy. (See 'Investigational strategies (inspiratory respiratory muscle training)' below.)

Physical therapy — Early mobilization/physical therapy in mechanically ventilated patients is supported by the American Thoracic Society and American College of Chest physicians as a preventive measure to promote liberation from mechanical ventilation [39,49]. Meta-analyses suggest that early mobilization/physical therapy shorten the duration of mechanical ventilation, but these analyses must be interpreted cautiously because of the heterogeneity of included studies [50,51]. Moreover, specific therapeutic strategies for difficult-to-wean patients have not been studied. Data discussing early ambulation in the ICU are provided separately. (See "Post-intensive care syndrome (PICS) in adults: Clinical features and diagnostic evaluation".)

Investigational strategies (inspiratory respiratory muscle training) — Inspiratory muscles can be trained to improve strength and endurance so that fatigue occurs less easily [52,53]. However, whether IMST consistently results in earlier liberation from mechanical ventilation remains unproven. Consequently, it is not routinely used.

IMST is performed by adding a resistance device to the inspiratory limb of the ventilator circuit. A systematic review of small randomized trials and observational studies reported that compared with sham or no training, inspiratory muscle training improved maximal inspiratory pressures (increase by -7 cm H2O), rapid shallow breathing index (+15 breaths/minute/L) (see "Weaning from mechanical ventilation: Readiness testing", section on 'Rapid shallow breathing index') and weaning success (risk ratio 1.34) [52]. Duration of mechanical ventilation improved only in the subgroup with known weaning difficulty. However, there was significant heterogeneity among trials suggesting that larger trials are needed to confirm or exclude this benefit. In a subsequent trial of tracheostomized patients, IMST resulted in improved muscle strength, 60-day survival (70 versus 49 percent), and weaning success (75 versus 45 percent) compared with traditional T-piece weaning [53]. However, the trial was small and had several limitations. A randomized trial of 104 tracheostomized patients found no improvement in weaning success or duration when comparing electronically assisted IMST with spontaneous breathing with T-piece [54].

REFRACTORY PATIENTS — Some patients remain difficult-to-wean even though their acute illness and factors contributing to failure to wean have been resolved. In such patients, a tracheostomy is frequently placed and the patient transferred to a long term acute care facility/hospital (LTAC/LTACH) where further weaning efforts can be undertaken (ie, prolonged weaning). (See 'Definition and incidence' above.)

Tracheostomy — A tracheostomy can be advantageous in those in whom weaning is expected to be prolonged. The advantages, disadvantages and timing of tracheostomy are discussed in detail separately. (See "Tracheostomy: Rationale, indications, and contraindications", section on 'Rationale for tracheostomy versus endotracheal tube' and "Tracheostomy: Rationale, indications, and contraindications", section on 'Optimal timing in mechanically ventilated patients'.)

Transfer to long-term acute care — The number of patients in specialized weaning units increased three-times between 1997 and 2006, reflecting the trend to manage such patients outside of the ICU [55]. Observational data suggests delaying ventilated patients' discharge to an LTAC may decrease the likelihood of successful weaning [56]. However, one single institution LTAC ventilator weaning trial reported that as many as a third of this population could have completed their wean in the ICU [57].

Several factors are considered when determining whether a patient is appropriate for transfer to a specialized weaning center. First, the acute illness should be resolved. Second, the patient should not be dyspneic or hypoxemic during mechanical ventilation. Third, patients should have a stable airway and route to receive nutrition, which usually consists of a tracheostomy and enteral feeding tube, respectively [58].

LTAC facilities provide a site where weaning and rehabilitation are the primary focus of care. They foster involvement of the patient in decision-making and provide an environment that integrates the family and other caregivers into a supportive health care team. This team includes intensivists, internists, nurses, and respiratory therapists who identify weaning goals and coordinate the weaning process. In addition, there is daily patient-centered rehabilitation that includes physical exercise for regaining muscle strength and practice performing activities of daily living. Skilled therapists are also available to focus on issues such as speech and communication, nutrition support, physical and recreational activities, and counseling. Strategies for weaning patients who are in an LTAC facility for prolonged mechanical ventilation and their outcomes are described in detail separately. (See "Discussing goals of care" and "Management and prognosis of patients requiring prolonged mechanical ventilation".)

A predictive index that has been proposed is the I-TRACH score. An I-TRACH score (Intubation in the ICU, tachycardia [heart rate >110 beats per minute], renal dysfunction [urea nitrogen level >25 mmol/L], acidemia [pH <7.25], creatinine [>2.0 or >50 percent increase from baseline values] and decreased bicarbonate level [HCO3 <20 mmol/L]) greater than or equal to four was predictive of subsequent need for mechanical ventilation beyond 7 and 14 days at the time of intubation [59]. The sensitivity was 61.8 percent, specificity 82 percent, positive predictive value 45.7 percent, and negative predictive value 89.8 percent for predicting >14 days of mechanical ventilator support.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Weaning from mechanical ventilation".)

SUMMARY AND RECOMMENDATIONS

Definition – Patients are considered difficult-to-wean if they fail their first spontaneous breathing trial (SBT) and then require up to three SBTs or seven days to pass an SBT. Up to 40 percent of patients mechanically ventilated for an acute illness in the intensive care unit (ICU) are difficult-to-wean. (See 'Definition and incidence' above.)

Correct the cause – Repeat unsuccessful attempts at weaning usually signify incomplete resolution of the illness that precipitated mechanical ventilation and/or the development of one or more new problems that prevent weaning. The clinician should identify and treat these issues (eg, respiratory, cardiac, psychological, circuit, nutritional) (table 1) before resuming further weaning trials. (See 'Identify and correct the cause' above.)

Resume weaning – Once the potential causes have been identified and treated, weaning trials may resume. SBTs are similar to those undergoing first time weaning except special attention should be paid to comfortable posture, airway management, and appropriate ventilation in between trials; in addition trials are typically longer (up to two hours) and PSV without PEEP or T-piece trials may be preferred in those with cardiac dysfunction. (See 'Resuming weaning trials' above.)

Respiratory muscle strength training – Early mobilization/physical therapy in mechanically ventilated patients should be used as a preventive measure to promote liberation from mechanical ventilation. However, specific therapeutic strategies for difficult-to-wean patients have not been studied. Inspiratory muscle training is of unclear benefit and therefore, not typically used. (See 'Investigational strategies (inspiratory respiratory muscle training)' above and 'Improving respiratory muscle strength' above.)

Refractory patients – Some patients remain difficult-to-wean even though their acute illness and factors contributing to failure to wean have been resolved. In such patients, a tracheostomy is frequently placed and the patient transferred to a long term acute care facility/hospital where further weaning efforts can be undertaken (ie, prolonged weaning). (See 'Transfer to long-term acute care' above and 'Refractory patients' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Martin F Joyce-Brady, MD, who contributed to earlier versions of this topic review.

  1. Boles JM, Bion J, Connors A, et al. Weaning from mechanical ventilation. Eur Respir J 2007; 29:1033.
  2. Funk GC, Anders S, Breyer MK, et al. Incidence and outcome of weaning from mechanical ventilation according to new categories. Eur Respir J 2010; 35:88.
  3. Peñuelas O, Frutos-Vivar F, Fernández C, et al. Characteristics and outcomes of ventilated patients according to time to liberation from mechanical ventilation. Am J Respir Crit Care Med 2011; 184:430.
  4. Jeong BH, Ko MG, Nam J, et al. Differences in clinical outcomes according to weaning classifications in medical intensive care units. PLoS One 2015; 10:e0122810.
  5. Béduneau G, Pham T, Schortgen F, et al. Epidemiology of Weaning Outcome according to a New Definition. The WIND Study. Am J Respir Crit Care Med 2017; 195:772.
  6. Routsi C, Stanopoulos I, Zakynthinos E, et al. Nitroglycerin can facilitate weaning of difficult-to-wean chronic obstructive pulmonary disease patients: a prospective interventional non-randomized study. Crit Care 2010; 14:R204.
  7. Mekontso-Dessap A, de Prost N, Girou E, et al. B-type natriuretic peptide and weaning from mechanical ventilation. Intensive Care Med 2006; 32:1529.
  8. Valentini I, Tonveronachi E, Gregoretti C, et al. Different tracheotomy tube diameters influence diaphragmatic effort and indices of weanability in difficult to wean patients. Respir Care 2012; 57:2012.
  9. Ezingeard E, Diconne E, Guyomarc'h S, et al. Weaning from mechanical ventilation with pressure support in patients failing a T-tube trial of spontaneous breathing. Intensive Care Med 2006; 32:165.
  10. Razazi K, Boissier F, Neuville M, et al. Pleural effusion during weaning from mechanical ventilation: a prospective observational multicenter study. Ann Intensive Care 2018; 8:103.
  11. Razazi K, Thille AW, Carteaux G, et al. Effects of pleural effusion drainage on oxygenation, respiratory mechanics, and hemodynamics in mechanically ventilated patients. Ann Am Thorac Soc 2014; 11:1018.
  12. Umbrello M, Mistraletti G, Galimberti A, et al. Drainage of pleural effusion improves diaphragmatic function in mechanically ventilated patients. Crit Care Resusc 2017; 19:64.
  13. Liu J, Shen F, Teboul JL, et al. Cardiac dysfunction induced by weaning from mechanical ventilation: incidence, risk factors, and effects of fluid removal. Crit Care 2016; 20:369.
  14. Li S, An YZ, Ren JY, et al. Myocardial injury after surgery is a risk factor for weaning failure from mechanical ventilation in critical patients undergoing major abdominal surgery. PLoS One 2014; 9:e113410.
  15. Cabello B, Thille AW, Roche-Campo F, et al. Physiological comparison of three spontaneous breathing trials in difficult-to-wean patients. Intensive Care Med 2010; 36:1171.
  16. Grasso S, Leone A, De Michele M, et al. Use of N-terminal pro-brain natriuretic peptide to detect acute cardiac dysfunction during weaning failure in difficult-to-wean patients with chronic obstructive pulmonary disease. Crit Care Med 2007; 35:96.
  17. Chien JY, Lin MS, Huang YC, et al. Changes in B-type natriuretic peptide improve weaning outcome predicted by spontaneous breathing trial. Crit Care Med 2008; 36:1421.
  18. Konomi I, Tasoulis A, Kaltsi I, et al. Left ventricular diastolic dysfunction--an independent risk factor for weaning failure from mechanical ventilation. Anaesth Intensive Care 2016; 44:466.
  19. Mekontso Dessap A, Roche-Campo F, Kouatchet A, et al. Natriuretic peptide-driven fluid management during ventilator weaning: a randomized controlled trial. Am J Respir Crit Care Med 2012; 186:1256.
  20. Goudelin M, Champy P, Amiel JB, et al. Left ventricular overloading identified by critical care echocardiography is key in weaning-induced pulmonary edema. Intensive Care Med 2020; 46:1371.
  21. Sanfilippo F, Di Falco D, Noto A, et al. Association of weaning failure from mechanical ventilation with transthoracic echocardiography parameters: a systematic review and meta-analysis. Br J Anaesth 2021; 126:319.
  22. Ruiz-Bailén M, Cobo-Molinos J, Castillo-Rivera A, et al. Stress echocardiography in patients who experienced mechanical ventilation weaning failure. J Crit Care 2017; 39:66.
  23. Dres M, Teboul JL, Anguel N, et al. Passive leg raising performed before a spontaneous breathing trial predicts weaning-induced cardiac dysfunction. Intensive Care Med 2015; 41:487.
  24. Dres M, Teboul JL, Anguel N, et al. Extravascular lung water, B-type natriuretic peptide, and blood volume contraction enable diagnosis of weaning-induced pulmonary edema. Crit Care Med 2014; 42:1882.
  25. Tanios M, Epstein S, Sauser S, Chi A. Noninvasive monitoring of cardiac output during weaning from mechanical ventilation: a pilot study. Amer J Crit Care 2016; 25:257.
  26. Ferré A, Guillot M, Lichtenstein D, et al. Lung ultrasound allows the diagnosis of weaning-induced pulmonary oedema. Intensive Care Med 2019; 45:601.
  27. Jubran A, Lawm G, Kelly J, et al. Depressive disorders during weaning from prolonged mechanical ventilation. Intensive Care Med 2010; 36:828.
  28. Jeon K, Jeong BH, Ko MG, et al. Impact of delirium on weaning from mechanical ventilation in medical patients. Respirology 2016; 21:313.
  29. Holliday JE, Hyers TM. The reduction of weaning time from mechanical ventilation using tidal volume and relaxation biofeedback. Am Rev Respir Dis 1990; 141:1214.
  30. Buckley MS, Smithburger PL, Wong A, et al. Dexmedetomidine for Facilitating Mechanical Ventilation Extubation in Difficult-to-Wean ICU Patients: Systematic Review and Meta-Analysis of Clinical Trials. J Intensive Care Med 2021; 36:925.
  31. Girault C, Breton L, Richard JC, et al. Mechanical effects of airway humidification devices in difficult to wean patients. Crit Care Med 2003; 31:1306.
  32. Georgopoulos D, Prinianakis G, Kondili E. Bedside waveforms interpretation as a tool to identify patient-ventilator asynchronies. Intensive Care Med 2006; 32:34.
  33. Laghi F, Tobin MJ. Disorders of the respiratory muscles. Am J Respir Crit Care Med 2003; 168:10.
  34. Kou HW, Yeh CH, Tsai HI, et al. Sarcopenia is an effective predictor of difficult-to-wean and mortality among critically ill surgical patients. PLoS One 2019; 14:e0220699.
  35. Krishnan JA, Parce PB, Martinez A, et al. Caloric intake in medical ICU patients: consistency of care with guidelines and relationship to clinical outcomes. Chest 2003; 124:297.
  36. Mancebo J, Amaro P, Lorino H, et al. Effects of albuterol inhalation on the work of breathing during weaning from mechanical ventilation. Am Rev Respir Dis 1991; 144:95.
  37. Dhand R, Jubran A, Tobin MJ. Bronchodilator delivery by metered-dose inhaler in ventilator-supported patients. Am J Respir Crit Care Med 1995; 151:1827.
  38. Hashemian SM, Mortaz E, Jamaati H, et al. Budesonide facilitates weaning from mechanical ventilation in difficult-to-wean very severe COPD patients: Association with inflammatory mediators and cells. J Crit Care 2018; 44:161.
  39. Girard TD, Alhazzani W, Kress JP, et al. An Official American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults. Rehabilitation Protocols, Ventilator Liberation Protocols, and Cuff Leak Tests. Am J Respir Crit Care Med 2017; 195:120.
  40. Perkins GD, Mistry D, Gates S, et al. 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; 320:1881.
  41. Burns KE, Adhikari NK, Keenan SP, Meade MO. Noninvasive positive pressure ventilation as a weaning strategy for intubated adults with respiratory failure. Cochrane Database Syst Rev 2010; :CD004127.
  42. Yeung J, Couper K, Ryan EG, et al. Non-invasive ventilation as a strategy for weaning from invasive mechanical ventilation: a systematic review and Bayesian meta-analysis. Intensive Care Med 2018; 44:2192.
  43. Vaschetto R, Longhini F, Persona P, et al. Early extubation followed by immediate noninvasive ventilation vs. standard extubation in hypoxemic patients: a randomized clinical trial. Intensive Care Med 2019; 45:62.
  44. Fernandez MM, González-Castro A, Magret M, et al. Reconnection to mechanical ventilation for 1 h after a successful spontaneous breathing trial reduces reintubation in critically ill patients: a multicenter randomized controlled trial. Intensive Care Med 2017; 43:1660.
  45. Sklar MC, Dres M, Fan E, et al. Association of Low Baseline Diaphragm Muscle Mass With Prolonged Mechanical Ventilation and Mortality Among Critically Ill Adults. JAMA Netw Open 2020; 3:e1921520.
  46. DiNino E, Gartman EJ, Sethi JM, McCool FD. Diaphragm ultrasound as a predictor of successful extubation from mechanical ventilation. Thorax 2014; 69:423.
  47. Goligher EC, Dres M, Fan E, et al. Mechanical Ventilation-induced Diaphragm Atrophy Strongly Impacts Clinical Outcomes. Am J Respir Crit Care Med 2018; 197:204.
  48. Cottereau G, Dres M, Avenel A, et al. Handgrip Strength Predicts Difficult Weaning But Not Extubation Failure in Mechanically Ventilated Subjects. Respir Care 2015; 60:1097.
  49. Schmidt GA, Girard TD, Kress JP, et al. Official Executive Summary of an American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults. Am J Respir Crit Care Med 2017; 195:115.
  50. Worraphan S, Thammata A, Chittawatanarat K, et al. Effects of Inspiratory Muscle Training and Early Mobilization on Weaning of Mechanical Ventilation: A Systematic Review and Network Meta-analysis. Arch Phys Med Rehabil 2020; 101:2002.
  51. Lippi L, de Sire A, D'Abrosca F, et al. Efficacy of Physiotherapy Interventions on Weaning in Mechanically Ventilated Critically Ill Patients: A Systematic Review and Meta-Analysis. Front Med (Lausanne) 2022; 9:889218.
  52. Elkins M, Dentice R. Inspiratory muscle training facilitates weaning from mechanical ventilation among patients in the intensive care unit: a systematic review. J Physiother 2015; 61:125.
  53. da Silva Guimarães B, de Souza LC, Cordeiro HF, et al. Inspiratory Muscle Training With an Electronic Resistive Loading Device Improves Prolonged Weaning Outcomes in a Randomized Controlled Trial. Crit Care Med 2021; 49:589.
  54. Roceto Ratti LDS, Marques Tonella R, Castilho de Figueir do L, et al. Inspiratory Muscle Training Strategies in Tracheostomized Critically Ill Individuals. Respir Care 2022; 67:939.
  55. Kahn JM, Benson NM, Appleby D, et al. Long-term acute care hospital utilization after critical illness. JAMA 2010; 303:2253.
  56. Demiralp B, Koenig L, Xu J, et al. Time spent in prior hospital stay and outcomes for ventilator patients in long-term acute care hospitals. BMC Pulm Med 2021; 21:104.
  57. Jubran A, Grant BJ, Duffner LA, et al. Effect of pressure support vs unassisted breathing through a tracheostomy collar on weaning duration in patients requiring prolonged mechanical ventilation: a randomized trial. JAMA 2013; 309:671.
  58. Scheinhorn DJ, Hassenpflug MS, Votto JJ, et al. Ventilator-dependent survivors of catastrophic illness transferred to 23 long-term care hospitals for weaning from prolonged mechanical ventilation. Chest 2007; 131:76.
  59. Clark PA, Inocencio RC, Lettieri CJ. I-TRACH: Validating A Tool for Predicting Prolonged Mechanical Ventilation. J Intensive Care Med 2018; 33:567.
Topic 1646 Version 29.0

References

آیا می خواهید مدیلیب را به صفحه اصلی خود اضافه کنید؟