Clinical Consultation: Noninvasive ventilation for COPD

Using noninvasive ventilation to manage COPD exacerbations When should noninvasive positive pressure ventilation (NPPV) be considered for patients with an exacerbation of chronic obstructive pulmonary disease (COPD)?

NPPV should be considered the ventilatory modality of first choice in patients presenting to an acute care hospital with an exacerbation of COPD. This is based on the findings of multiple randomized controlled trials as well as meta-analyses. These have shown that NPPV used in such patients brings about a more rapid improvement in dyspnea, vital signs, and PaCO₂ than does oxygen therapy with standard medical treatment. Use of NPPV results in significant reductions in the need for intubation, morbidity and mortality rates, and in some studies, the length of hospital stay. These latter benefits are unquestionably related to the avoidance of the complications of intubation, including nosocomial infections, that increase in occurrence as the duration of intubation becomes prolonged.

However, NPPV should not be used indiscriminately in patients with COPD exacerbations. Although most patients appear to be good candidates, some patients are too mildly ill and others have contraindications to the use of NPPV. For example, patients with relatively mild derangements of gas exchange and no more than mild dyspnea will probably do fine without any ventilatory assistance and should not be placed on NPPV. Conversely, patients who have progressed to the point of respiratory arrest or who have become hemodynamically unstable should be promptly intubated to gain control of the airway. Likewise, patients who have excessive secretions, are unable to protect their airway, or are uncooperative should not be treated with NPPV. The ideal candidate is a patient with moderate to severe dyspnea, increased use of the accessory muscles of breathing, and evidence of acute-on-chronic carbon dioxide retention on arterial blood gases. According to the randomized studies, such patients have up to a 50% likelihood of requiring intubation, which can be reduced to 20% or less with the use of NPPV.

NPPV can also be used for COPD patients in special clinical situations. For example, patients who have undergone lung resection surgery and have respiratory failure after extubation do better with NPPV than with standard medical therapy, and those with a do-not-intubate status have a better than even chance of surviving the hospitalization if they are treated with NPPV. Even when the exacerbation is complicated by coma resulting from carbon dioxide retention or pneumonia, the outcome of management with NPPV is often favorable.

Successful implementation of NPPV requires interaction with and encouragement of the patient, as well as the involvement of a physician, respiratory therapist, and nurses who are experienced and confident with its application. Selection of a well-fitting and comfortable mask, proper ventilator settings, and judicious monitoring are important. If patients fail to improve or remain intolerant beyond the first 2 hours of NPPV initiation, endotracheal intubation should be seriously considered, if still indicated, because an unanticipated respiratory arrest often spells disaster for patients with acute respiratory failure.

Treatment of acute respiratory failure caused by an exacerbation of COPD is the number one clinical application of NPPV, and proper application can be anticipated to improve patient outcomes. However, NPPV is not for every patient with a COPD exacerbation; it must be applied selectively by skilled and experienced caregivers if its potential benefits are to be realized.