Treatment of Acute COPD Exacerbation

Many patients require oxygen supplementation during a COPD exacerbation, even those who do not need it chronically. Hypercapnia may worsen in patients given oxygen. This worsening has traditionally been thought to result from an attenuation of hypoxic respiratory drive. However, increased ventilation/perfusion (V/Q) mismatch probably is a more important factor.

Before oxygen administration, pulmonary vasoconstriction minimizes V/Q mismatch by decreasing perfusion of the most poorly ventilated areas of the lungs. Increased V/Q mismatch occurs because oxygen administration attenuates this hypoxic pulmonary vasoconstriction.

The Haldane effect may also contribute to worsening hypercapnia, although this theory is controversial. The Haldane effect is a decrease in hemoglobin's affinity for carbon dioxide, which results in increased amounts of carbon dioxide dissolved in plasma. Oxygen administration, even though it may worsen hypercapnia, is recommended; many patients with COPD have chronic as well as acute hypercapnia and thus severe central nervous system depression is unlikely unless PaCO2 is > 85 mm Hg. The target level for PaO2 is about 60 mm Hg; higher levels offer little advantage and increase the risk of hypercapnia.

In patients who are prone to hypercarbia (ie, an elevated serum bicarbonate may indicate the presence of a compensated respiratory acidosis), oxygen is given via nasal prongs or Venturi mask so it can be closely regulated, and the patient is closely monitored. Patients whose condition deteriorates with oxygen therapy (eg, those with severe acidemia or central nervous system depression) require ventilatory assistance.

Many patients who require oxygen at home for the first time when they are discharged from the hospital after an exacerbation improve within 30 days and no longer require oxygen. Thus, the need for home oxygen should be reassessed 60 to 90 days after discharge.

Noninvasive positive-pressure ventilation Noninvasive positive pressure ventilation (NIPPV) (eg, pressure support or positive airway pressure ventilation by face mask) is an alternative to full mechanical ventilation. Noninvasive ventilation appears to decrease the need for intubation, reduce hospital stay, and reduce mortality in patients with severe exacerbations (defined as a pH < 7.30 in hemodynamically stable patients not at immediate risk of respiratory arrest).

Noninvasive ventilation appears to have no effect in patients with less severe exacerbation. However, it may be indicated for patients with less severe exacerbations whose arterial blood gases (ABGs) worsen despite initial drug or oxygen therapy or who appear to be imminent candidates for full mechanical ventilation but who do not require intubation for control of the airway or sedation for agitation. Patients who have severe dyspnea, hyperinflation, and use of accessory muscles of respiration may also gain relief from positive airway pressure. Deterioration while receiving noninvasive ventilation necessitates invasive mechanical ventilation Overview of Mechanical Ventilation Mechanical ventilation can be Noninvasive, involving various types of face masks Invasive, involving endotracheal intubation Selection and use of appropriate techniques require an understanding... read more .

Deteriorating ABG values, deteriorating mental status, and progressive respiratory fatigue are indications for endotracheal intubation and mechanical ventilation Overview of Mechanical Ventilation Mechanical ventilation can be Noninvasive, involving various types of face masks Invasive, involving endotracheal intubation Selection and use of appropriate techniques require an understanding... read more . Ventilator settings, management strategies, and complications are discussed elsewhere Means and Modes of Mechanical Ventilation Mechanical ventilation can be Noninvasive, involving various types of face masks Invasive, involving endotracheal intubation Selection and use of appropriate techniques require an understanding... read more . Risk factors for ventilatory dependence include an FEV1 < 0.5 L, stable ABGs with a PaO2 < 50 mm Hg, or a PaCO2 > 60 mm Hg, severe exercise limitation, and poor nutritional status. Therefore, if patients are at high risk, discussion of their wishes regarding intubation and mechanical ventilation should be initiated and documented (see Advance Directives Advance Directives Advance directives are legal documents that extend a person's control over health care decisions in the event that the person becomes incapacitated. They are called advance directives because... read more ) while they are stable outpatients. However, overconcern about possible ventilator dependence should not delay management of acute respiratory failure; many patients who require mechanical ventilation can return to their pre-exacerbation level of health.

High-flow nasal oxygen therapy has also been used for patients with acute respiratory failure due to a COPD exacerbation and can be tried for those who do not tolerate noninvasive mask ventilation.

In patients who require prolonged intubation (eg, > 2 weeks), a tracheostomy is indicated to facilitate comfort, communication, and eating. With a good multidisciplinary pulmonary rehabilitation program Pulmonary Rehabilitation Pulmonary rehabilitation is the use of supervised exercise, education, support, and behavioral intervention to improve functional capacity and enhance quality of life in patients with chronic... read more , including nutritional and psychologic support, many patients who require prolonged mechanical ventilation can be successfully removed from a ventilator and can return to their former level of function. Specialized programs are available for patients who remain ventilator-dependent after acute respiratory failure. Some patients can remain off the ventilator during the day. For patients with adequate home support, training of family members can permit some patients to be sent home with ventilators.

Beta-agonists and anticholinergics, with or without corticosteroids, should be started concurrently with oxygen therapy (regardless of how oxygen is administered) with the aim of reversing airway obstruction. Methylxanthines, once considered essential to treatment of acute COPD exacerbations, are no longer used; toxicities exceed benefits.

In patients with very severe disease, exercise is unwarranted and activities of daily living are arranged to minimize energy expenditure. For example, patients may arrange to live on one floor of the house, have several small meals rather than fewer large meals, and avoid wearing shoes that must be tied. End-of-life care The Dying Patient Dying patients can have needs that differ from those of other patients. So that their needs can be met, dying patients must first be identified. Before death, patients tend to follow 1 of 3... read more should be discussed, including whether to pursue mechanical ventilation, the use of palliative sedation, and appointment of a surrogate medical decision-maker in the event of the patient’s incapacitation.