Ventilatory Strategies in Obstructive Lung Disease

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by expiratory flow limitation (EFL) due to progressive airflow obstruction. The various mechanisms that cause EFL are central to understanding the physiopathology of COPD. At the end of expiration, dynamic inflation may occur due to incomplete emptying the lungs. This "extra" volume increases the alveolar pressure at the end of the expiration, resulting in auto-positive end-expiratory pressure (PEEP) or PEEPi. Acute exacerbations of COPD may result in increased airway resistance and inspiratory effort, further leading to dynamic hyperinflation. COPD exacerbations may be triggered by environmental exposures, infections (viral and bacterial), or bronchial inflammation, and may result in worsening respiratory failure requiring mechanical ventilation (MV). Acute exacerbations of COPD need to be distinguished from other events such as cardiac failure or pulmonary emboli. Strategies to treat acute respiratory failure (ARF) in COPD patients include noninvasive ventilation (NIV), pressure support ventilation, and tracheal intubation with MV. In this review, we discuss invasive and noninvasive techniques to address ARF in this patient population. When invasive MV is used, settings should be adjusted in a way that minimizes hyperinflation, while providing reasonable gas exchange, respiratory muscle rest, and proper patient-ventilator interaction. Further, weaning from MV may be difficult in these patients, and factors amenable to pharmacological correction (such as increased bronchial resistance, tracheobronchial infections, and heart failure) are to be systematically searched and treated. In selected patients, early use of NIV may hasten the process of weaning from MV and improve outcomes.

A comparison of synchronized intermittent mandatory ventilation and pressure-regulated volume control ventilation in elderly patients with acute exacerbations of COPD and respiratory failure

“…Hyperinflation can induce barotrauma and further injury to the lungs, which may prolong the duration of mechanical ventilation. 10 Barotrauma is a type of lung damage caused by the application of high airway pressure. 11 The most common form of barotrauma is pneumothorax, which can be detected on a chest radiograph when the lateral lung regions collapse.…”

Rehabilitation of Difficult-to-Wean, Tracheostomized Patients Admitted to Specialized Unit: Retrospective Analyses over 10-Years

“…On the other hand, weaning achievement tended to be better in the second period. It is possible that this may have been due to the smaller proportion of patients with COPD, who are often recognized as difficult-to-wean once tracheostomized [ 20 ], with an urgent need for advanced care [ 21 ].…”

Acute Exacerbations of Chronic Obstructive Pulmonary Disease: Diagnosis, Management, and Prevention in Critically Ill Patients

“…Hyperinflation may lead to barotrauma and further acute lung injury, which may prolong the duration of mechanical ventilation. Other nonpharmacologic maneuvers to optimize mechanical ventilation include reduction in respiratory rate and/or tidal volume, raising the inspiratory flow rate, and application of extrinsic PEEP …”

“…Similar to NIPPV, the FiO 2 is set to keep the PaO 2 > 60 mm Hg or the arterial blood oxygen saturation of hemoglobin > 92% . Although the benefit in COPD is unknown, low tidal volumes (6–8 ml/kg based on ideal body weight) may be used as initial settings due to the concern for air trapping . Respiratory rate is set to achieve a goal minute ventilation.…”