Even experts may disagree with the classification of some cases.On spirometry, as a restrictive lung disease, both the FEV1 (forced expiratory volume in 1 second) and FVC (forced vital capacity) are reduced so the FEV1/FVC ratio is normal or even increased in contrast to obstructive lung disease where this ratio is reduced. The values for residual volume and total lung capacity are generally decreased in restrictive lung disease. Treatment
Pulmonary fibrosis creates scar tissue. The scarring is permanent once it has developed. Slowing the progression and prevention depends on the underlying cause:

Treatment options for idiopathic pulmonary fibrosis are very limited. Though research trials are ongoing, there is no evidence that any medications can significantly help this condition. Lung transplantation is the only therapeutic option available in severe cases. Since some types of lung fibrosis can respond to corticosteroids (such as prednisone) and/or other medications that suppress the bodys immune system, these types of drugs are sometimes prescribed in an attempt to slow the processes that lead to fibrosis.The immune system is felt to play a central role in the development of many forms of pulmonary fibrosis. The goal of treatment with immune suppressive agents such as corticosteroids is to decrease lung inflammation and subsequent scarring. Responses to treatment are variable.
It does this by binding to oxyhaemoglobin to release cyanide, methaemoglobin and nitric oxide. NO activates guanylate cyclase in vascular smooth muscle and increases intracellular production of cGMP. cGMP activates protein kinase G which activates phosphatases which inactivate myosin light chains. Myosin light chains are involved in smooth muscle contraction. The result is vascular smooth muscle relaxation, which allow vessels to dilate. This mechanism is similar to that of phosphodiesterase 5 (PDE5) inhibitors such as sildenafil (Viagra) and tadalafil (Cialis), which elevate cGMP concentration by inhibiting its degradation by PDE5.A role for NO in various common psychiatric disorders including schizophrenia, bipolar disorder and major depressive disorder has been proposed and supported by several clinical findings. These findings may also implicate the potential of drugs that alter NO signalling such as SNP in their treatment. Such a role is also supported by the findings of the recent SNP clinical trial. Structure and properties
Nitroprusside is an inorganic compound with the formula Na2[Fe(CN)5NO], usually encountered as the dihydrate, Na2[Fe(CN)5NO]·2H2O. This red-colored sodium salt dissolves in water or ethanol to give solutions containing the free complex dianion [Fe(CN)5NO]2−. Nitroprusside is a complex anion that features an octahedral iron(II) centre surrounded by five tightly bound cyanide ligands and one linear nitric oxide ligand (Fe-N-O angle = 176.2 °). The anion possesses idealized C4vsymmetry. Due to the linear Fe-N-O angle, the relatively short N-O distance of 113 pm and the relatively high stretching frequency of 1947 cm−1, the complex is formulated as containing an NO+ ligand.