COMMENTARY

Managing Ventilation in Acute Cardiogenic Pulmonary Edema

Greg Martin, MD, MSc

Disclosures

August 14, 2008

Noninvasive Ventilation in Acute Cardiogenic Pulmonary Edema

Gray A, Goodacre S, Newby DE, Masson M, Sampson F, Nicholl J
N Engl J Med. 2008;359:142-151

Respiratory compromise may develop in patients with cardiogenic pulmonary edema (CPE) or these patients may require respiratory support. Recent developments with noninvasive positive-pressure ventilation (NIPPV) have established its use in chronic obstructive pulmonary disease exacerbations; data for patients with CPE suggest physiologic benefit but uncertainly regarding survival.[1,2] This study randomized 1069 critically ill patients with CPE to receive either standard oxygen therapy or NIPPV (further randomized to either continuous positive airway pressure [CPAP] or biphasic positive airway pressure [BIPAP]), titrated to achieve adequate oxygenation (SpO2 > 92%). They found that NIPPV resulted in greater reductions at 1 hour in dyspnea, heart rate, acidosis, and hypercapnia. There were no differences in mortality between any groups, and no differences between the 2 forms of NIPPV. In addition, there were no differences in the development of respiratory failure or the need for endotracheal intubation and mechanical ventilation. The authors concluded that, in patients with CPE, use of NIPPV results in more rapid improvement in respiratory symptoms and signs of distress, without complications and without an improvement in survival.

 

Viewpoint

This study was undertaken to determine whether NIPPV improves survival in patients with CPE and to compare different methods of delivering NIPPV (CPAP and BIPAP). This is particularly relevant given that a previous meta-analysis suggested an increased risk for myocardial infarction in patients treated with BIPAP,[3] despite that BIPAP has the physiologic advantages of producing greater improvements in oxygenation, carbon dioxide clearance, and work of breathing.[4] The primary finding of no difference in the development of respiratory failure is surprising, as previous studies have shown benefit.[5,6,7] One possible interpretation of this study is that they found physiologic improvements with NIPPV compared with standard oxygen therapy (as expected), but did not see reductions in respiratory failure or mortality resulting from different use of NIPPV compared with other studies. In this study, CPAP was begun at 5 cm H2O and increased to a maximum of 15 cm H2O; BIPAP was started with an inspiratory pressure of 8 cm H2O and an expiratory pressure of 4 cm H2O, and could be titrated up to 20 and 10 cm H2O, respectively. An alternative explanation is that this study, being larger and more potentially more homogeneous than previous studies, may reflect the true effect of NIPPV in patients with CPE. Unfortunately, these results are insufficiently definitive regarding how to manage patients with CPE. For patients with CPE and incipient respiratory failure, as in this study, use of NIPPV appears to improve physiology and dyspnea symptoms, but does not improve clinical outcomes. Given that predicting the development of or progression to respiratory failure is difficult at best and that use of NIPPV appears safe (in either CPAP or BIPAP mode), its cautious application may be appropriate for this population of patients with CPE. However, further studies are required to hone the evidence in this area.

Abstract

Viewpoint

This study was undertaken to determine whether NIPPV improves survival in patients with CPE and to compare different methods of delivering NIPPV (CPAP and BIPAP). This is particularly relevant given that a previous meta-analysis suggested an increased risk for myocardial infarction in patients treated with BIPAP,[3] despite that BIPAP has the physiologic advantages of producing greater improvements in oxygenation, carbon dioxide clearance, and work of breathing.[4] The primary finding of no difference in the development of respiratory failure is surprising, as previous studies have shown benefit.[5,6,7] One possible interpretation of this study is that they found physiologic improvements with NIPPV compared with standard oxygen therapy (as expected), but did not see reductions in respiratory failure or mortality resulting from different use of NIPPV compared with other studies. In this study, CPAP was begun at 5 cm H2O and increased to a maximum of 15 cm H2O; BIPAP was started with an inspiratory pressure of 8 cm H2O and an expiratory pressure of 4 cm H2O, and could be titrated up to 20 and 10 cm H2O, respectively. An alternative explanation is that this study, being larger and more potentially more homogeneous than previous studies, may reflect the true effect of NIPPV in patients with CPE. Unfortunately, these results are insufficiently definitive regarding how to manage patients with CPE. For patients with CPE and incipient respiratory failure, as in this study, use of NIPPV appears to improve physiology and dyspnea symptoms, but does not improve clinical outcomes. Given that predicting the development of or progression to respiratory failure is difficult at best and that use of NIPPV appears safe (in either CPAP or BIPAP mode), its cautious application may be appropriate for this population of patients with CPE. However, further studies are required to hone the evidence in this area.

Abstract

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