**1. Introduction**

332 Chronic Obstructive Pulmonary Disease – Current Concepts and Practice

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> Noninvasive positive pressure ventilation (NPPV) refers to the administration of ventilatory support without using an invasive artificial airway (endotracheal tube or tracheostomy tube). The use of NPPV has markedly increased over the past two decades. Rudimentary devices that provided continuous positive airway pressure were described in the 1930s, but the negative-pressure ventilators were the predominant method of ventilatory support until the polio epidemics overwhelmed their capacity in the 1950s. In the 1980s, increasing experience with positive-pressure ventilation delivered through a mask in patients with obstructive sleep apnea led to this type of ventilatory support, initially in patients with neuromuscular respiratory failure. Success led to its adoption in other conditions, and NPPV became especially promising in the treatment of patients with exacerbations of chronic obstructive pulmonary disease (COPD).

> NPPV is defined as ventilatory support delivered by a non-invasive interface such as mask or similar device, acting as an alternative to intubation or tracheostomy. Consequently, by avoiding tracheal intubation, NPPV presents several potential advantages, such as reduction in pulmonary infections, barotrauma and need for sedation (British Thoracic Society Standards of Care Committee 2002). As a result, NPPV should be considered a standard of care to treat COPD exacerbation in selected patients, since it markedly reduces the need for intubation and improves outcome by lowering complication and mortality rates, and shortening hospital stay (Brochard et al. 1995; Kramer et al. 1995; Celikel et al. 1998; Martin et al. 2000; Conti et al. 2002; Squadrone et al. 2004; Lightowler et al. 2003; Nava, Navalesi, & Conti 2006). Weaker evidence indicates that NPPV could allow earlier extubation, avoid reintubation in patients who fail extubation, and assist do-not-intubate patients, and thus could be beneficial for COPD patients who are suffering respiratory failure precipitated by superimposed pneumonia or postoperative complications, and COPD patients with severe stable disease who have substantial daytime hypercapnia and superimposed nocturnal hypoventilation.

> This chapter will examine the evidence pertaining to the use of NPPV for various applications in COPD and make recommendation on patient, ventilation mode and interface selection as well as technical aspects of NPPV application in COPD. The literature review

Noninvasive Positive-Pressure Ventilation Therapy in Patients with COPD 335

support in patients with either a severe exacerbation of COPD or cardiogenic pulmonary edema(Keenan et al. 2011). Furthermore, consensus groups of experts advocate the routine use of NPPV for selected patients with COPD exacerbations (British Thoracic Society Standards of Care Committee 2002). High quality studies have shown that NPPV is an effective treatment for moderate to severe COPD exacerbation (Kramer et al. 1995; Celikel et al. 1998; Martin et al. 2000). In patients with mild to moderate ARF, characterized by pH levels between 7.25 and 7.35, the rate of NPPV failure was ranging from 15% to 20% (Elliott 2002; Lightowler et al. 2003). In more severely ill patients (pH<7.25), the rate of NPPV failure was inversely related to the severity of respiratory acidosis, rising up to 52%-62% (Conti et al. 2002; Squadrone et al. 2004). In patients with ''mild'' exacerbations, not complicated by respiratory acidosis, the use of NPPV was investigated in few studies, including patients in large majority with pH>7.35, which failed to demonstrate a better effectiveness of NPPV than standard medical therapy in preventing the occurrence of ARF (Bardi et al. 2000; Keenan, Powers, & McCormack 2005). Guidelines recommend the use of NPPV in addition to usual care in patients who have a severe exacerbation of COPD (pH<7.35 and relative hypercarbia) (grade 1A recommendation) (Keenan et al. 2011). Based on that evidence, the authors of the meta-analyses and the participants in the consensus groups recommended that NPPV should be used early in the course of a COPD exacerbation, in addition to the standard medical care (Lightowler et al. 2003; Keenan et al. 2003; British Thoracic Society Standards of Care Committee 2002) . NPPV is not appropriate for all COPD patients with ARF and the selection of candidates is important. Most of the indications and contraindications for NPPV in ARF are listed in Table 1 (Brochard et al. 1995). There are no absolute contraindications to NPPV although a number have been suggested (Ambrosino et al. 1995; Soo Hoo, Santiago, & Williams 1994). In part, these contraindications have been determined by the fact that they were exclusion criteria for the controlled trials. It is therefore accurate to state that NPPV is not proven in these

circumstances rather than stating that it is contraindicated.

in non-COPD patients.

**3.3 Adjunct to early liberation** 

**3.2 Severe community-acquired pneumonia in patients with COPD** 

The presence of pneumonia has been associated with poor outcome in patients treated with NPPV (Ambrosino et al. 1995). However COPD exacerbation is still an appropriate indication for NPPV even when complicated by community-acquired pneumonia (Confalonieri et al. 1999). In one randomized trial with patients suffering severe communityacquired pneumonia, NPPV reduced the need for intubation, and reduced mortality among the COPD subgroup of patients 2 months after hospital discharge (Confalonieri et al. 1999). But it is not clear whether NPPV should be used for severe community-acquired pneumonia

Patients with COPD can be considered for a trial of early extubation to NPPV in centres with extensive experience in the use of NPPV (Keenan et al. 2011). Guidelines suggest that NPPV be used to facilitate early liberation from mechanical ventilation in patients who have COPD, but only in centres that have expertise in this therapy (Grade 2B recommendation) (Keenan et al. 2011). Recent randomized controlled trials (RCTs) suggested benefit from NPPV after extubation in patients who had high risk of deterioration (Ferrer et al. 2006; Ferrer et al. 2009; Nava et al. 2005; Luo, Cheng, & Zhou 2001). The results of the RCTs of

and consensus processes used to reach the recommendations presented here are the American College of Chest Physicians [ACCP] consensus report on clinical indications for NPPV in CRF due to restrictive lung disease, COPD and nocturnal hypoventilation published in 1999, the British Thoracic Society guidelines published in 2002, the Indian Society of Critical Care Medicine guidelines published in 2006, the guidelines from 12 German Medical Societies published in 2008 and the most recent guideline published in 2011 from Canadian Critical Care Trials Group/Canadian Critical Care Society Noninvasive Ventilation Guidelines Group.
