Noninvasive Ventilation: Still Underused in Acute Respiratory Failure
Abstract & Commentary
By David J. Pierson, MD, Editor
Synopsis: Nationwide from 2000-2009, there was a steady increase in the use of noninvasive ventilation (NIV) in managing acute respiratory failure, although the percentage of potentially eligible patients who receive it remains small. Importantly, the proportional increase was less for chronic obstructive pulmonary disease ([COPD] in which the evidence is compelling and NIV is the standard of care) than for non-COPD causes of respiratory failure (in which the evidence is weaker or conflicting).
Source: Walkey AJ, Wiener RS. Use of noninvasive ventilation in patients with acute respiratory failure, 2000-2009: A population-based study. Ann Am Thorac Soc 2013;10:10-17.
Using discharge data from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project from the Agency for Healthcare Research and Quality (AHRQ) for the years 2000-2009, Walkey and Wiener investigated population-based trends in the use of noninvasive ventilation (NIV) among patients with a diagnosis code for acute respiratory failure (ARF). Their objective was to compare utilization trends and outcomes with NIV use in patients with and without chronic obstructive pulmonary disease (COPD). Of the 78 million discharges from acute care hospitals nationwide during the study interval, the investigators identified 2,380,632 adults (3% of the total) whose hospitalization was coded for ARF. A diagnosis of COPD was present in 900,750 of these (37%). Across the United States, there was a steady increase in the population-based incidence of ARF over the 10-year study period. There was also a steady increase in the use of NIV among patients with ARF: from 8.6 to 39 per 100,000 U.S. residents for COPD, and from 6 to 39 per 100,000 for non-COPD causes. The use of invasive mechanical ventilation increased 7% for COPD patients with ARF compared to a 73% increase for non-COPD causes of ARF.
The proportion of patients with COPD who received NIV increased 250% during the study period, but only from 3.5% in 2000 to 12.3% in 2009. The corresponding percentages for patients with non-COPD ARF were 1.2% and 6.0% (a 400% increase). Thus, from 2000 to 2009, the rate of “uptake” for NIV as a ventilation approach for ARF in U.S. hospitals was greater for non-COPD causes of ARF than for exacerbations of COPD. The authors also examined outcomes of NIV — specifically NIV failure and the subsequent use of invasive mechanical ventilation — for patients with COPD and cardiogenic pulmonary edema, conditions in which the evidence supporting its use is strongest, as compared with those with pneumonia, sepsis, and other causes for ARF with weaker or conflicting evidence in favor of NIV. NIV was more likely to fail in this latter group. In addition, patients who required invasive ventilation after NIV failure were more likely to die in the hospital than patients who received mechanical ventilation via endotracheal tube from the beginning.
NIV is now well established as the standard of care for ARF complicating COPD, in which setting it reduces mortality, complications, lengths of stay, and costs. For other causes of ARF, the strength of the evidence supporting NIV varies from fairly solid in cardiogenic pulmonary edema to much less strong (or contradictory, or lacking) in most other clinical settings. Thus, the findings in this population-based study covering a period in which the evidence supporting NIV in COPD was already well known, with practice guidelines recommending its use, are discouraging. The overall use of NIV in ARF did increase across the United States from 2000-2009 — but only to about 1 in 8 patients with COPD — and it increased even more proportionally in circumstances (non-COPD) for which NIV is not generally the standard of care.
Two other recent studies deserve mention. Chandra and colleagues examined data from the AHRQ’s Healthcare Cost and Utilization Project’s Nationwide Inpatient Sample to study trends in NIV usage in patients admitted because of acute exacerbations of COPD (AECOPD).1 Among 7.5 million U.S. admissions for AECOPD from 1998-2008, the use of NIV steadily increased. However, as in the Walkey study, the proportions remained discouragingly low: from 1.0% to 4.5% of all patients. Chandra et al did not study ARF per se, but focused on the condition (AECOPD) in which the evidence of benefit from NIV, in the setting of a severe exacerbation, is most compelling. In their study, only in the last year of the 11-year observation period did NIV overtake invasive mechanical ventilation as the most frequently used form of ventilatory support in these patients.
Unlike the clinical trials in which the efficacy of NIV in AECOPD and other settings for ARF has been investigated — with the conditions of interest carefully defined and therapy administered according to study protocols — the Walkey and Chandra studies looked at the real-world use of NIV for ARF across America. Similarly, in the April issue of the Journal of Hospital Medicine, Tsai and colleagues report on their study of NIV use among patients with AECOPD who are admitted through the emergency department.2 They used data from the 2006-2008 Nationwide Emergency Department Sample, a component of the AHRQ’s Healthcare Cost and Utilization Project. Of approximately 101,000 visits for AECOPD in each of the study years, 96% resulted in hospital admission. The use of NIV in admitted patients ranged from 14% in 2006 to 16% in 2008 (P = 0.049 for the increase). However, among the 4700 hospitals whose data were included in the study, usage of NIV in patients with AECOPD varied enormously — from 100% to 0%, with a median of 11% of patients. NIV use tended to be greater in high-case volume Northeastern hospitals.
By propensity score analysis, NIV use, compared with invasive mechanical ventilation, was associated with lower inpatient mortality (risk ratio, 0.54; 95% confidence interval [CI], 0.50-0.59), shortened hospital length of stay (-3.2 days; 95% CI, -3.4 to -2.9 days), lower hospital charges (-$35,012; 95% CI, -$36,848 to -$33,176), and lower risk of iatrogenic pneumothorax (0.05% vs 0.5%, P < 0.001). Thus, while also confirming previous findings of the beneficial effects of NIV in AECOPD, Tsai et al documented the low overall use of this therapy as recently as 2008.
These studies all suffer from their use of administrative databases (that is, discharge coding) rather than clinical data to identify patients with ARF, COPD, and other diagnoses, as well as from not having examined the study questions prospectively. Nonetheless, the message seems clear: As in many other areas of health care, “clinical uptake” — the translation of research findings into bedside day-to-day practice — lags way behind the evidence. In their thoughtful editorial accompanying the Chandra study, Elliott and Nava consider the possible reasons for this in the case of NIV for AECOPD.3 It is hard to accept “unfamiliarity with the evidence” on the part of intensivists and respiratory therapists, as a reason, since surely in 2013 everyone practicing critical care has to know that NIV improves outcomes in AECOPD. But ingrained practices are hard to change. In the respiratory care field, especially, knowledge translation has been challenging despite strong evidence in a number of areas.4 Let us hope that future studies using databases from the current decade will show a dramatic increase in the use of NIV in those settings — AECOPD especially — in which it has been shown to save lives and improve other outcomes in the everyday practice of critical care.
1. Chandra D, et al. Outcomes of noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease in the United States, 1998-2008. Am J Respir Crit Care Med 2012; 185:152-159.
2. Tsai CL, et al. Comparative effectiveness of noninvasive ventilation vs invasive mechanical ventilation in chronic obstructive pulmonary disease patients with acute respiratory failure. J Hosp Med 2013;8:165-172.
3. Elliott MW, Nava S. Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease: “Don’t think twice, it’s alright!”. Am J Respir Crit Care Med 2012;185:121-123.
4. Pierson DJ. Translating evidence into practice. Respir Care 2009; 54:1386-1401.