Hemodynamic Effects of Oxygen Therapy in Patients With Acute Exacerbations of Chronic Obstructive Pulmonary Disease: Materials and Methods
The effects of long-term oxygen therapy in patients with COPD are well known. A decrease in pulmonary hypertension accompanied by an improvement in the quality of life and survival rate of these patients has been reported previously; however, the changes in hemodynamic and oxygen transport variables induced by oxygen therapy in patients during acute exacerbations are less well understood.
The reported hemodynamic effects of oxygen therapy during acute exacerbations differ among investigators. Abraham et al found no change in cardiac output. Degaute et al studied 35 patients with acute exacerbations of COPD during the first day of admission after withdrawal of oxygen therapy. These investigators found that reintroduction of oxygen therapy caused a drop in the cardiac output and an increase in oxygen delivery (Do2) due to an improvement in arterial oxygen saturation (Sa02). Pulmonary artery pressure did not change. Lejeune et al, in a series of 17 patients with acute exacerbations of COPD studied during the first 3 days of hospitalization, observed a decrease in cardiac output induced by oxygen therapy, whereas pulmonary vascular resistance did not change.
All of those studies were done in patients during the first few days of hospitalization, and hemodynamic changes were investigated after withdrawal of oxygen therapy. We designed our study to investigate the effects of controlled oxygen therapy on hemodynamic parameters in patients with acute exacerbations of COPD shortly after arriving at the emergency department, before receiving oxygen therapy.
We studied 15 consecutive patients (10 male patients; mean age, 62 ±7 years) admitted to the emergency department with acutely decompensated COPD, due to acute bronchitis. The diagnosis of COPD was based on the patients history, physical examination, chest x-ray film, arterial blood gas levels, and ECG. A history of daily expectoration during at least 3 months of the year during at least 2 consecutive years was required for the diagnosis of COPD. Eleven patients provided the results of previous pulmonary function tests showing airway obstruction (ratio of forced expiratory volume in 1 s over forced vital capacity <60 percent of the predicted value). The chest x-ray film obtained on admission showed no infiltrates, cardiomegaly, or significant pleural effusions. Four patients were febrile (peripheral temperature above 38.0°C) and became afebrile within the first 36 h in the ICU. The initial white blood cell count was 12,245/mnv±782/mmJ. The general condition of all patients improved while in the ICU, allowing discharge after a mean stay of 5.8 ±0.5 days.