Treatment of Pulmonary Hypertension in Interstitial Lung Disease
Limited data suggest that the treatment of pulmonary hypertension in ILD is beneficial. Enough oxygen to limit exercise and nocturnal hypoxemia should be a focus of care.
Trakada et al.[11] studied 38 patients with ILD and oxygen saturation above 90% at rest during the daytime with nocturnal polysomnography. They observed that all 38 (100%) experienced nocturnal hypoxemia to an oxygen saturation at least below 85%, and they suggested that screening for nocturnal hypoxemia should be standard in these diseases.
There are some theoretic risks to vasodilation in patients with ILD. If pulmonary artery vasodilation leads to improved blood flow into areas of fibrotic lung, then worsening of ventilation perfusion mismatch may result. This would be manifested by lower oxygen concentrations either at rest or with activity. Whether significant worsening of hypoxemia occurs with oral or systemic vasodilators remains to be shown in larger clinical trials. Small studies have suggested that hypoxemia may occur. This has been shown in some scleroderma patients with ILD who were treated with epoprostenol.[15] Ghofrani et al.[16] administered inhaled nitric oxide, intravenous epoprostenol, or oral sildenafil to 16 patients with pulmonary hypertension and ILD. Although all three agents decreased pulmonary vascular resistance, the patients receiving intravenous prostacyclin experienced decreased arterial oxygen tension, largely because of an increase in shunt fraction. By contrast, inhaled nitric oxide and sildenafil maintained ventilation perfusion matching and decreased pulmonary vascular resistance without a decrease in arterial oxygen tension.
There is a theoretic benefit in matching ventilation and pulmonary vasodilation with an inhaled medication such as iloprost. In a pilot study by Olshewski et al.,[17] eight patients with ILD and severe pulmonary hypertension were given epoprostenol, inhaled nitric oxide, or inhaled iloprost. Systemic arterial pressure, arterial oxygen saturation, and pulmonary right-to-left shunt flow, measured by multiple inert gas analysis, were not significantly changed; however, pulmonary vascular resistance fell and was associated with significant clinical improvement in some of the patients.
The advancement of therapies for pulmonary hypertension in ILD will require carefully designed clinical trials that will focus on both short-term and long-term endpoints. Although survival may ultimately be affected, short-term studies of gas exchange, exercise tolerance, and quality of life should be sufficient to speed therapies to the bedside of these difficult-to-treat patients. Printer- Friendly Email This