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Antonio M. Esquinas (ed.)Noninvasive Mechanical Ventilation and Difficult Weaning in Critical Care10.1007/978-3-319-04259-6_2020. Use of Noninvasive Ventilation to Facilitate Weaning fromMechanical Ventilation
(1)
Division of Pulmonary, Critical Care, and Sleep Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, MA, USA
Keywords
Noninvasive ventilationWeaningReintubationExtubation failureWeaning failure20.1 Introduction
Noninvasive positive-pressure ventilation (NIV), applied through various mask interfaces, improves outcomes in patients with acute respiratory failure secondary to acute exacerbation of chronic obstructive pulmonary disease (COPD), acute cardiogenic pulmonary edema, and hypoxemic respiratory failure with pulmonary infiltrates in immunocompromised patients. NIV has also been used to prevent, or treat, respiratory failure in patients undergoing planned extubation from mechanical ventilation [1]. Randomized controlled trials suggest that NIV may not be effective when applied to a heterogeneous group of patients with extubation failure, although a case control study suggests this therapy may be effective for patients with COPD with extubation failure [2, 3]. Similarly, NIV seems not to prevent extubation failure (defined as the need for reintubation) when it is applied nonselectively to all extubated patients [4]. By contrast, NIV improves outcome (decreased reintubation, decreased pneumonia, shorter duration or mechanical ventilation and length of stay, improved survival) when it is used as preventive therapy in cohorts of patients deemed to be at high risk for extubation failure [5, 6]. With the exception of some patients in the Jiang study, NIV was used in these investigations only when a patient had successfully passed a spontaneous breathing trial (SBT), indicating that mechanical ventilatory support was no longer required. These studies raise the question of whether NIV can be used in the patient who is ready to initiate weaning but who is not yet able to tolerate an SBT. In other words, can NIV be used to facilitate weaning?
20.2 Rationale for Using NIV
Patients who are intubated and mechanically ventilated for acute respiratory failure are at increased risk for complications, including upper airway injury, respiratory muscle weakness, gastrointestinal bleeding, thromboembolism, sinusitis, and ventilator-associated pneumonia. The latter is particularly important given its association with increased morbidity and possibly increased mortality. The risk for complications and the risk of mortality rise with increasing duration of mechanical ventilation. Needlessly delaying extubation in a patient who otherwise seems to be ready also causes harm, as such patients experience increased risk for pneumonia, length of stay, and mortality compared with patients expeditiously extubated. On the other hand, numerous studies have found that patients who pass an SBT and undergo planned extubation but require reintubation (extubation failure) have increased risk for complications, prolonged hospital stay, and significantly increased mortality [7].
Therefore, an essential task for ICU clinicians is trying to wean and successfully extubate patients as expeditiously (and safely) as possible. A series of studies published in the 1990s indicated that between 15 and 35 % of patients mechanically ventilated with acute respiratory failure fail an initial trial of spontaneous breathing and will require a more prolonged weaning process. These studies, for the most part, relied on clinician intuition for determining readiness for weaning. More recently, investigators have noted that, depending on the patient population studied, 40–70 % of patients do not tolerate their initial SBT. This observation is likely related to the more aggressive screening criteria used to identify the earliest time when spontaneous breathing can be undertaken.
Given the similarities between the pathophysiology of weaning failure and that of acute respiratory failure, NIV may have a role to play in facilitating weaning. As with acute respiratory failure, weaning failure is often characterized by an imbalance between respiratory muscle capacity and the respiratory load confronted by those muscles (i.e., the work of breathing). The latter can result from increased resistive or elastic work of breathing, the effects of intrinsic positive end-expiratory pressure (PEEP), and abnormal gas exchange. When used to treat patients with acute respiratory failure, NIV is capable of reducing the work of breathing, providing respiratory muscle unloading (including offsetting the effects of intrinsic PEEP), improving alveolar ventilation, and increasing oxygenation. In so doing, NIV decreases the risk for intubation, reduces important complications such as pneumonia, and improves survival. There is increasing recognition that weaning failure may result from cardiovascular abnormalities including ischemia, increased preload and afterload resulting from the negative intrathoracic pressure that occurs during spontaneous breathing, and an inability to adequately increase cardiac output to meet the metabolic demands of the SBT. As demonstrated in studies of acute cardiogenic pulmonary edema, NIV can counteract these factors and result in improved cardiac performance and decreased cardiogenic pulmonary edema.
By exchanging the endotracheal tube for a noninvasive interface, NIV may have additional benefits. With the removal of the endotracheal tube, any increased work of breathing imposed by the artificial airway is eliminated. Removal of the endotracheal tube improves patient comfort and the ability to communicate, reduces the need for sedation, and restores the capacity for effective cough; all factors that could contribute to successful weaning and extubation.
20.3 Preliminary Studies
Based on the rationale above, NIV has the potential to facilitate the weaning process in patients who are ready for spontaneous breathing but who cannot yet pass a SBT. Observational studies, reported in the 1990s, indicated the potential of NIV to promote successful weaning. Udwadia et al. [8] reported that 82 % of 22 difficult to wean patients (mean duration of ventilation, 31 days), with various causes for respiratory failure, could be successfully liberated from mechanical ventilation by the use of nasal NIV. Similarly, Restrick and colleagues [9] found the use of NIV resulted in 93 % weaning success in 14 weaning failure patients, including 8 with COPD. In a third study, 13 of 15 patients were successfully extubated to NIV after satisfying criteria not typically associated with satisfactory completion of an SBT (PaO2 ≥40 mmHg on a fraction of inspired oxygen (FiO2) of 0.21, PaCO2 ≤55 mmHg, pH >7.32, respiratory rate ≤40 breaths/min, frequency/tidal volume ratio of ≤190 breaths/l/min) [10].
20.4 Randomized Controlled Trials
Over the last two decades, a number of randomized controlled trials have addressed whether NIV, when compared with invasive weaning with the endotracheal tube in place, can successfully facilitate weaning in patients who are not tolerating SBTs.
Nava and colleagues [11] randomized 50 COPD patients (40 % of whom had failed NIV prior to intubation) with acute-on-chronic respiratory failure who had failed a 2-h SBT to weaning with the endotracheal tube in place (using pressure support) or direct extubation to NIV delivered with an oronasal mask. Patients randomized to NIV experienced shorter time on mechanical ventilation, decreased ICU stay, higher likelihood of successful weaning, and improved 60-day survival.
Using a similar study design, Girault et al. [12] randomized 33 patients with acute-on-chronic respiratory failure and found that NIV reduced the duration of intubation while other outcomes were unchanged. Interestingly, total mechanical ventilation time (time intubated plus time on NIV) was more than a week greater in the NIV group.
Ferrer and coworkers [13] randomized 43 patients, including 77 % with chronic lung diseases, after they had failed a minimum of three SBTs. This study was terminated at the first interim analysis because of the overwhelming benefits associated with weaning facilitated by NIV. NIV, compared with weaning performed while the patient remained intubated, was associated with reductions in the duration of intubation, ICU and hospital stay, need for tracheostomy, and development of pneumonia. NIV was associated with increased ICU and 90-day survival.Related posts:
Predictive Models of Prolonged Mechanical Ventilation and Difficult Weaning
Noninvasive Technique of Nasal Intermittent Pressure Ventilation (NIPPV) in Patients with Chronic Obstructive Lung Disease After Failure to Wean from Conventional Intermittent Positive-Pressure Ventilation (IPPV): Key Practical Topic and Implications
Noninvasive Mechanical Ventilation in Postoperative Bariatric Surgery
Noninvasive Mechanical Ventilation in Tetraplegia
Criteria for Discharging Patients with Prolonged and Difficult Weaning from Intensive Care Unit to Weaning Center
Organization of a Weaning Unit
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