Predictors of Mortality in Patients With Advanced Lung Disease in Home Oxygen Therapy

The advanced chronic lung disease (PAD) is characterized by the development of several structural abnormalities, and pulmonary and systemic functional with low potential for reversibility, in spite of the treatment. It is defined DPA whole lung non-neoplastic chronic in its final phase. Most people with DPA consists of elderly people who have lung function and quite compromised gas exchange. These conditions determine chronically limitations in activities of daily living, negative impact on mental and social state, frequent exacerbations of the disease and numerous hospitalizations, recognized risk factors for increased morbidity and mortality (MACHADO, 2006).

Clinically, patients with APD may have one or more of the following signs and symptoms: dyspnea; cough; intolerance efforts; hypoxemia and / or hypercapnia; malnutrition and / or cachexia; anxiety and / or depression (BTS 2004).

According Garden 2004, the DPA affects millions of people worldwide and it is estimated that in Brazil there are two million individuals with APD. The most prevalent lung diseases, which in the final stage, fall under the DPA definition are classified as obstructive, restrictive, vascular and hypoventilation syndromes. Obstructive chronic respiratory insufficiency are part individuals with COPD, bronchiectasis and other bronchiolitis. Already restrictive covers patients with interticiais diseases and neuromuscular diseases. And the pulmonary vascular diseases fit patients with primary pulmonary hypertension and secondary and chronic pulmonary thromboembolism (MACHADO, 2006; PAUL, 2005).

Within the restrictive diseases with high prevalence we find the interticiais diseases are heterogeneous disorders, grouped according to clinical, radiological and functional similar. In the group of conditions that account for the majority of advanced pulmonary diseases are idiopathic pulmonary fibrosis, hypersensitivity pneumonitis and sarcoidosis. The etiology is unknown in many situations; and any known causes that stand out are the tobacco-related diseases (Guidelines interticiais lung diseases, 2012).

Vascular diseases also fits in advanced lung disease and presents significant pulmonary and systemic changes in patients. Before insulting stimuli of different nature, the pulmonary vessels undergo changes, known as pathological remodeling of the circulation. The vessel is tougher and reactive, causing pulmonary vascular diseases. Morphologic lesions in the arterial tree leads to local changes in the pattern of blood flow, that flow slowly added to the changes detected in the endothelial surface and abnormalities of the coagulation system proteins provide local thrombus formation. Pulmonary hypertension is a pathological condition that is present when the mean pulmonary artery pressure above 25 mmHg (CONSENSUS, 2009).

The alveolar hypoventilation is the major injury to the respiratory function by obesity. The concept of alveolar hypoventilation reflects the incompetence of the respiratory system to eliminate carbon dioxide in the same proportion that reaches the lungs. Implies, therefore, the presence hypercapnia (PaCO2> 45 mm Hg) accompanied by equivalent degree of hypoxemia (low PaO 2). Alveolar hypoventilation syndrome-obesity is defined as chronic alveolar hypoventilation in obese patients (body mass index greater than 30 kg / m2), without any other respiratory disease to justify the disorder of gas exchange. Palliative treatment consists in controlling chronic hypoventilation and hypoxemia and resolute treatment is to combat obesity (SILVA, GA 2006).

Among the obstructive diseases of major relevance are bronchiectasis and COPD. Bronchiectasis refers to the dilatation of the bronchi and irreversible distortion due to the destruction of the elastic and muscle component of its wall. It can be congenital or acquired. To purchase no need to aggression by an infection and disability in hygiene bronchial secretions. The patient has a cough, possibly with episodes of hemoptysis (GARDEN, 2004).

COPD is a preventable and treatable respiratory disease characterized by the presence of chronic airflow obstruction that is not fully reversible. The airflow obstruction is usually progressive and associated with an abnormal inflammatory response of the lungs to inhaled particles or toxic gases. Although COPD affects the lungs, it also produces significant systemic consequences that contribute to disease severity (GOLD - Global Obstructive Lung Disease, 2013).

The ODP is considered a non-pharmacological treatment critical for patients with chronic respiratory insufficiency. Maintaining low and stable level of oxygen in blood is of great importance for the organic homeostasis. Oxygen supplementation improves survival of patients with chronic hypoxemia and your prescription is recommended in the consensus on the subject. The main benefits of oxygen to the body are the decline in ventilatory work and improves the cardiovascular and muscular functions (Machado, 2006).

Classical studies have found that the use of ODP for more than 15 h / day in patients with chronic respiratory diseases increases survival in patients with severe hypoxemia (Lancet, 1981; Ann Intern Med, 1980...). The use of oxygen is indicated in patients with (as GOLD - Global Obstructive Lung Disease, 2013):

• PaO2 mmHg or SpO2 ≤ 55 ≤ 88, with or without hypercapnia confirmed two times over a period of 3 weeks, or
• = 55 to 60 mmHg PaO2 or SaO2 = 89%, with evidence of pulmonary hypertension, or polycythemia (hematocrit> 55%) The number of patients who require ODP is increasing every year. This type of therapy is being used more frequently in order to reduce morbidity and mortality and improve the quality of life of patients. This practice allows you to optimize the occupation of the beds, reduce the length and the number of hospitalizations and thus reduce hospital costs (Tanni, S. E et al 2007).

Two large studies have evaluated the benefits of ODP. The first study conducted by the Medical Research Concil compared the use of oxygen for 15h / d X 0 h / d, showing improved survival in those patients who regularly used oxygen. The second study, the Nocturnal Oxygen Therapy Trial, compared the use of 24h / d with 12h / d, showing improved survival in those patients who used oxygen for longer (Nocturnal Oxygen Therapy Trial Group, 1980).

The DPA's are an important public health problem in the world. Many people suffering from these diseases for years and die prematurely from the disease itself or its complications. The DPA, particularly COPD, are classified as a major cause of morbidity and mortality worldwide and results in an economic and social impact is substantial and growing, the debt is having a major highlight in the medical field in recent years (Gold, 2013).

Thus this work will identify the predictors of mortality in patients with DPA in ODP and help professionals and public and private policy health directly linked to treat these patients, to optimize the clinical management, helping improve the treatment of these patients, increasing life expectancy, reducing costs and improving the quality of life of these patients.