PURPOSE: COPD embarrasses respiration by irreversable mechanisms. Emphysematous change increases respiratory work not only through airway obstruction but also through V/Q derangements which cause hypoxemia, increased Dead Space ventilation and a resulting requirement for increased total ventilation. These latter present a therapeutic opportunity. Inhalation of vasodilating gas (NO) improves gas exchange in COPD but is cumbersome, requiring specialized equipment. Iloprost is a prostacyclin analogue which is used by inhalation to treat Pulmonary Hypertension. Its mode of action is pulmonary vasodilation which occurs mainly at its site of deposition. We have thus investigated the effect of Iloprost aerosol inhalation on gas exchange in patients with COPD.
METHODS: Eight patients (5 male, 3 female, aged 68±8 years) with COPD were studied. Baseline spirometry, TLC, DlCO, ABG’s and exercise oximetry were measured. Then, an inhalation treatment was given which provided a pulmonary deposition of 10 mcg of Iloprost. The initial studies were repeated and the results of the pre- and post-treatment evaluations were compared using Student’s T test for paired data.
RESULTS: All patients tolerated Iloprost inhalation easily with no detectable changes in heartrate, respiratory rate or blood pressure. All expressed improvement in their sense of respiratory comfort. There were no posttreatment changes in pulmonary mechanics but the mean DlCO rose from 8.3ml/min to 11.5ml/min (p<.03) and the mean AaDO2 on room air fell from 36mmHg to 31mmHg (p<.05). A 2 flight pretreatment stairclimb caused a mean drop of 9.5% in SaO2 and an increase of 24 bpm in heartrate with a mean postexercise recovery time to baseline values of 6.4 minutes. The same stairclimb posttreatment resulted in reduced desaturation, tachycardia and recovery time (4%, 14bpm and 1 minute respectively). These changes were all significant at p<.02.
CONCLUSION: Iloprost inhalation improves V/Q matching in COPD, reducing both Dead Space ventilation and Shunt perfusion, especially during increased respiratory demand.
CLINICAL IMPLICATIONS: Inhalational pulmonary vasodilators should be further investigated as an adjunct to the treatment of COPD, especially in the setting of acute exacerbation.
DISCLOSURE: William Marino, None.