Abstract
Aims: To evaluate the outcomes of NIV versus invasive mechanical ventilation in COPD patients.
Data Source: Relevant articles were identified from the following journals CHEST, Respiratory Care, European Respiratory Journal, Annals of Internal Medicine, and AHC Media.
Study selection: The articles identified consisted reports of two randomized controlled trials and three review articles which investigated the outcomes of NIV versus mechanical ventilation in patients with acute exacerbations of COPD, weaning of COPD patients on mechanical ventilation, and nocturnal management of COPD.
Data extraction: The study reviewed meta-analytic reviews, prospective randomized control trials, and retrospective observational studies. The various studies compared the outcomes of NIV versus invasive mechanical ventilation in terms of the following outcomes: improvements in gas exchange, vital signs, arterial blood gases, rates of endotracheal intubation (ETI), need for tracheostomy, weaning success rates, length of mechanical ventilation, length of ICU and hospital stay, 60-day survival rates, health- related quality of life, mortality rates amongst other patient outcomes.
Results: NIV is used to manage acute exacerbations of COPD, nocturnal COPD, and to wean COPD patients’ previously on mechanical ventilation. NIV has more favorable outcomes than invasive mechanical ventilation in terms of improving parameters such as gas exchange, arterial blood gases, vital signs, rates of nosocomial infections, length of ICU and overall hospital stay and reducing ETI rates and hospital charges in patients with acute deteriorations and during weaning. Contradictory findings have, however, been reported on the outcomes of NIV use to treat stable COPD.
Conclusion: NIV improves patient outcomes when used to manage acute deteriorations of COPD and to wean mechanically ventilated COPD patients requiring prolonged ventilation. The use of NIV to treat nocturnal COPD is controversial.
Introduction
Non-invasive ventilation (NIV) refers to positive-pressure ventilator support delivered without an artificial airway such as an endotracheal tube or tracheostomy tube. 1 NIV is delivered via nasal, oronasal, or full face masks. 2 The technique dates back to the 1950s when it was first applied to patients with polio. At this time, negative pressure was applied to a patient’s chest wall. 1 Currently, it is in most instances applied as positive pressure to the opening of an airway. 1 Patients with chronic pulmonary obstructive disease (COPD) usually tend to have weakness of respiratory muscles, hypercapnia, hypoxia, and malnutrition. 3 In addition, they often experience acute secondary exacerbations that necessitate prolonged mechanical ventilation. The latter and endotracheal intubations are associated with an increased risk for nosocomial infections and mortality. 4 NIV has been proposed as a more favorable alternative to mechanical ventilation. 1,4 This paper will review and compare the outcomes of NIV vis-a-vis those of invasive ventilation in patients with COPD.
Methods
Previously published journal articles from the following journals CHEST, Respiratory Care, European Respiratory Journal, Annals of Internal Medicine, and AHC Media were identified through a search of Pubmed and an open internet search conducted between the 14th and 17th of July 2013. The following search terms were used COPD, noninvasive mechanical ventilation, NIV, invasive ventilation, mechanical ventilation, and patient outcomes. Abstracts to all articles were read to establish their relevance to the topic of the study. Articles whose contents were found to be pertinent to the study were downloaded and their contents abstracted. Notably, methodological screening of the studies was not done hence the study findings were accepted as reported by the original authors.
Results
The review noted that the use of NIV in the management of patients with COPD is significantly underutilized. NIV use in the studies evaluated was done in ICU, emergency, ward, long-term care, and home settings. The studies reviewed evaluated NIV use in the management of acute exacerbations of COPD, patients with stable COPD, and in the weaning of COPD patients already on mechanical ventilation. These studies included meta-analytic reviews, prospective randomized control trials, and retrospective observational studies. The outcomes assessed in these studies included improvements in gas exchange, vital signs, arterial blood gases, rates of endotracheal intubation (ETI), need for tracheostomy, weaning success rates, length of mechanical ventilation, length of ICU and hospital stay, 60-day survival rates, health-related quality of life, mortality rates amongst other patient outcomes. Findings from most of these studies suggest that NIV improves the outcomes of patients with COPD as compared to conventional invasive ventilation except in the day-to-day management of COPD symptoms.
Outcomes of NIV use for Acute Exacerbations of COPD
The efficacy of NIV in the management of acute deteriorations of COPD is extensively studied. The benefits of NIV therapy were first demonstrated in a 1990 case control study. 3 Findings from the strongest levels of research evidence garnered from subsequent studies further suggest that NIV is effective in the management of acute exacerbations of COPD. 5 Two of these studies were meta-analyses by Keenan et al. (2003) and Ram et al. (2004 as cited in Garpestand, Brennan, and Hill, 2007). 5 They both suggest that NIV promotes more rapid improvements in gas exchange, PH, and vital signs, has a lesser need for intubation (risk reduction 28%; relative risk 0.41; 95% CL 0.33 to 0.53), reduces mortality (relative risk, 0.52; risk reduction 10%; 95% CI, 0.35 to 0.76), decreases the incidence of complications, and it decreases the length of hospital stay. These findings have also been confirmed in a number of prospective randomized trials. In one such study by Kramer et al. (1995 as cited in Brochard, 2003), 4 the authors found that patients in the NIV group had a significantly reduced need for ETI (67% to 9%).
Studies conducted outside ICU settings have also concluded that NIV reduces the need for ETI, rate of complications, shortens hospital stays, and it improves survival. The largest of these studies was conducted in the UK by Brochard et al. (1995 as cited in Brochard, 2003)4 and enrolled 85 patients. The patients in the study were randomized to treatment with face mask pressure support ventilation and to a control group without this treatment. The study established that NIV reduced the need for ETI (26% vs. 65%) The reduction in ETI rates for the NIV group was associated with a lesser number of complications during the ICU stay, a significant reduction in mortality (29 to 9%), and a reduction in the duration of hospital stay. The overall decrease in mortality rates was attributed to the reductions in ETI rates and ICU-related complications. A retrospective study by Tsai et al. (2008) that employed a retrospective cohort design similarly concluded that NIV use as compared to mechanical ventilation was associated with a shorter duration of hospital stay, lower inpatient mortality, and lesser hospital charges. 2 In light of these findings, the British Thoracic Society as well as an international consensus conference both recommended that NIV be considered the first-line therapy for patients with acute exacerbations of COPD. The British Thoracic Society further recommends that all hospitals should be able to provide NIV on a round-the-clock basis for this patient group. 4 The table below summarizes the findings of numerous randomized controlled trials that have evaluated the outcomes of NIV use in patients with COPD in different settings.
Outcomes of NIV use to Wean COPD patients on Mechanical Ventillation
The use of NIV to wean patients with COPD has also been explored. Patients with acute deteriorations of COPD often require invasive mechanical ventilation because they either fail NIV, exhibit a contraindication to NIV such as need for surgery, or they have indications of immediate ETI. 4 Patients in this group who have a need for protracted ventillatory assistance may, however, be switched to NIV after a number of days of ETI so as to reduce the duration of invasive ventilation. The latter approach has been shown to reduce the length of ETI in two randomized controlled trials. 4 In one of these studies, use of NIV reduced complications rates and at the same time improved the 60-day survival rate (92% vs. 72%; p= 0.009). The study was by Nava et al. (1998). The patients enrolled in the study had severe hypercapnic respiratory failure and sensory impairment. At 60 days, 88% of the patients who had been ventilated noninvasively were weaned successfully as compared to 68% of the patients ventilated invasively. The average duration of mechanical ventilation was 10.2 ±6.8 days for the NIV group and 16.6 ±11.8 days for the invasively ventilated group (p=0.021). The probability of survival and early weaning were higher for the NIV group (p=0.002). The duration of ICU stay was shorter for the NIV group than for the invasive ventilation group (15.1 ± 5.4 days vs. 24.9 ± 13.7 days; p= 0.005). In addition, none of the NIV patients developed nosocomial pneumonia while 7 of the invasively ventilated patients did.
Of note is that the traditional approach to weaning of invasively intubated patients is associated with high failure rates. The use of NIV in patients with persistent weaning failure has been proposed. A prospective randomized controlled study by Ferrer et al. (2003) showed that this approach to weaning of COPD patients improves patient outcomes as compared to the conventional weaning approach where patients continue to be intubated after weaning failure. The 43 patients enrolled in this study had failed weaning trials over three consecutive days. 4 Early extubation with NIV reduced the need for post- extubation tracheotomy, shortened the duration of mechanical ventilation and overall stay, reduced the incidence of complications, and it improved survival in the patients studied. 4
Outcomes of NIV use for everyday Management of COPD symptoms
Numerous observational studies and randomized controlled trials have also evaluated the use of NIV amongst patients with stable COPD. Patients with COPD often require prolonged mechanical ventilation at home or in long-term care settings. 1 NIV use is preferable for these patients because they only require ventilator support for a few hours during the day particularly at night and tracheostomy with its many associated complications is not advisable for partial use only. In addition, tracheostomies require a lot of care, are unsightly, and they impact on the patient’s quality of life.1 The various studies have, however, reported mixed findings on the impact of NIV on patient quality of life and overall effects in this patient group (Hess, 2012). For instance, a meta-analysis of 4 studies by Wijkstra (2003) concluded that NIV support did not enhance gas exchange, lung function, or sleep efficiency.1 NIV in the four studies evaluated was delivered via an oronasal or nasal mask for a minimum of 5 hours per day for at least 3 weeks. A more recent systematic review by Kolodziej et al. (2005) that incorporated 9 observational studies and 6 randomized controlled studies, on the other hand, reported that the use of NIV in patients with severe but stable COPD may improve gas exchange, work of breathing, dyspnea, frequency of hospitalization, functional status, and health-related quality of life. 1 Notably, the improvements in gas exchange described by the study were only noted in the observational studies. A randomized controlled trial by Diuverman et al. (2008) also reported that NIV improved several measures of gas exchange, functional status, and health-related quality of life in COPD patients receiving pulmonary rehabilitation.1 Therefore, the use of NIV in patients with stable COPD is controversial.1
Discussion
It is explicit from the findings described that both prospective randomized clinical trials and meta-analytic studies concur that NIV therapy has better patient clinical outcomes than invasive mechanical ventilation when used for patients with acute deteriorations of COPD. Meta-analytic studies constitute the strongest level of evidence followed by randomized clinical trials. As such, the study can confidently state that, in patients with acute exacerbations of COPD, NIV improves gas exchange, vital signs, and PH, reduces the need for ETI, reduces the rates of nosocomial infections, shortens the length of ICU and overall hospital stay, and it improves survival. These findings are consistent across ICU, ward, and emergency care settings. On account of these findings, NIV is now recommended as a first-line treatment in the management of acute exacerbations of COPD. NIV has also been shown to reduce the need for protracted invasive ventilation in COPD patients with acute deteriorations but who fail or do not qualify for NIV in the initial period. In this patient group, NIV reduces the duration of invasive ventilation and in effect, it reduces complication rates and it improves survival rates. Another area where NIV is useful is in the management of COPD patients who have failed weaning tests. In this patient population, NIV reduces the need for post-extubation ETI. The findings of studies on the outcomes of NIV in improving the symptoms and quality of life of COPD patients with nocturnal symptoms are, however, controversial. Therefore, more studies are needed in this area.
Conclusion
In summary, the studies evaluated indicate that NIV has more favorable outcomes as compared to invasive ventilation when used to manage acute exacerbations and to augment weaning of COPD patients already on mechanical ventilation. These improvements include better gas exchange, improved vital signs, shorter ICU and hospital stays, reduced rates of nosocomial infections, shorter duration of mechanical ventilation, reduced need for post-extubation tracheostomy amongst other benefits. As a result, NIV is now recommended as a first-line treatment for acute deteriorations of COPD. The findings on the use of NIV to control nightly symptoms of COPD are, however, mixed.
References
- Hess DR. The growing role of noninvasive ventilation in patients requiring prolonged mechanical ventilation. Respiratory Care 2012; 57(6), 900-918.
- Steinberg KP. Noninvasive ventilation is more effective than invasive mechanical ventilation for acute exacerbations of COPD but remains under-utilized. AHC Media 2013; 8(3).
- Nava S, Ambrosino N, Clini E, Prato M, Orlando G, Vitacca M, Brigada P, Fracchia C, Rubini F. Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease: A randomized controlled trial. Annals of Internal Medicine 1998; 128: 721-728.
- Brochard L. Mechanical ventilation: Inasive versus noninvasive ventilation. European Respiratory Journal 2003; 22 (47): 31s-37s.
- Garpestad E, Brennan J, Hill NS. Noninvasive ventilation for critical care. CHEST 2007; 132: 711-720.
