Disease Processes Appropriate For NIPPV

COPD. Chronic obstructive pulmonary disease (COPD) affects 32 million people in the United States and is the fourth leading cause of death.⁷ Often, this disease presents in respiratory extremis, and NIPPV has quickly emerged as a standard of care in treatment of severe exacerbations. When comparing NIPPV usage to treatment without it, multiple meta-analyses have revealed statistically significant reductions in intubation rates, mortality, and hospital length of stay.^8,9,10

In addition to these mortality and morbidity benefits, Lightowler’s meta-analysis showed significant physiological changes with NIPPV therapy. Within the first hour, patients exhibited improvement in pH, PaCO2, and respiratory rate.⁸ NIPPV can be utilized successfully in hypercapnic patients with a GCS less than 8 secondary to acute respiratory failure.⁶

As previously noted, the key to success with NIPPV usage is selection. A randomized, controlled trial by Keenan and colleagues showed that NIPPV therapy had no benefit versus standard therapy in mild COPD exacerbation.¹¹ One meta-analysis specifically analyzed NIPPV benefits in COPD exacerbations with hypercapnia (defined as PaCO2 greater than 45 mm Hg), and another meta-analysis defined severe COPD exacerbation as a pH less than 7.3.^8,9

In addition, the emergency physician must use the clinical picture to delineate between mild and severe COPD exacerbations. However, in severe COPD, noninvasive positive pressure ventilation must be considered standard therapy.

Congestive heart failure. Every year, congestive heart failure accounts for more than 1 million hospitalizations, and for patients older than 65 years, it is the leading discharge diagnosis in the United States.¹² Severe congestive heart failure exacerbations commonly manifest with pulmonary edema in the emergency department.

The use of NIPPV versus traditional therapy in cardiogenic pulmonary edema has been supported by several meta-analyses, most recently by Vital and colleagues in the Cochrane Database in 2008. NIPPV has demonstrated statistically significant decreased risk of intubation, as well as decreased in-hospital mortality.^13,14,15,16 Studies have also shown significant physiological improvements with NIPPV usage in respiratory rate, pH, PaCO2, PaO2, heart rate, work of breathing, afterload, preload, cardiac index, and ejection fraction.^{17,18,19,20,21,22}

Despite proven benefits of NIPPV in cardiogenic pulmonary edema, controversies still exist regarding its safety and efficacy. A trial by Mehta and colleagues in 1997 raised a concern of increased incidence of myocardial infarction with use of bilevel positive airway pressure (BiPAP) support versus continuous positive airway pressure (CPAP).¹⁷ However, subsequent trials have contradicted these findings and found no difference in myocardial infarction rate with any group.^23,24