A significant proportion of lung injury cases remain uninvestigated or are classified by their etiologies and presentations as having unknown causes. Some cases of lung injury are treated with antibiotics, anti-inflammatories, respiratory therapies, or physical therapy, mostly without evidence-based clinical practice guidelines. In addition, some patients have been hospitalized over years owing to the diagnostic difficulty in this field. No comprehensive, evidence-based clinical practice guidelines on lung injury management have been developed.
Lung injury, if untreated, will often result in pulmonary fibrosis and chronic obstructive pulmonary disease. Treatments have been developed at this time that have been shown to be effective in reducing the complications in both patients and in vitro. These are being evaluated in clinical trials at this time. There is no guarantee, however, that treatment will prevent the late progression to chronic obstructive lung disease, or that these treatments will reduce symptoms long-term in any specific population, and thus the question of whether lung injury can be cured is no longer relevant as treatment options have changed dramatically.
All inhaled toxins cause direct, tissue injury. Aspiration of stomach acid also results in direct damage to the esophagus, and the presence of gastric acid implies an increased propensity for aspiration. Damage may occur when inhalation of acid in conjunction with aspiration of stomach acid causes tissue necrosis. A further complication of acid aspiration is that, in severe form, the lung responds by proliferating and growing into an enlarged tissue mass, which can obstruct the airway and cause airway obstruction. Acid aspiration can also be associated with esophagitis, a complication of alcohol and peptic ulcer disease. A definitive cause of aspiration cannot be identified in about 20 percent of cases.
It is important to understand the different mechanisms of lung injury. There are three main mechanisms of lung injury: 1) direct damage by infection; 2) immune-mediated damage by antibody and other immune effectors; and 3) inflammatory processes.
Signs of lung injury include increased respiratory rate, shortness of breath, a hoarse voice, decreased oxygen saturation and a rapid heart rate. Signs of lung injury are common in patients with sepsis.
Around 5.7 million people in the USA are hospitalized each year, for primary or secondary diagnoses of lung injury. This would be a significant increase if you take into account the high rate of undiagnosed lung disease and asymptomatic pulmonary fibrosis, which would be more common and more severe in this population. Lung injury is estimated to cause 5.9 million days in outpatient and inpatient hospitalization per year in the USA alone. For comparison, 3 million new cancer cases are estimated to occur a year. This is a large increase that is more than seven times larger than all projected yearly diagnoses of lung cancer.
Inappropriate ventilation is associated with increased risk of pulmonary complications in ventilated patients. Using a FiO2 at a level that is thought to be safe for non-ventilated patients is likely to increase risk in critically ill patients as well.
Oxygen fractions of up to 100% appear to be safe and should be administered to people who do not breathe spontaneously or in whom the use of positive pressure ventilation is contraindicated during the acute phase of illness.
All of the above studies provide significant insight into the pathological and molecular mechanisms of pulmonary injury. A great challenge to lung pathologists is to find a practical, clinically applicable approach, enabling detection of early disease in patients requiring the most effective therapeutic options and possibly improving survival.
A major complaint of the patients suffering from bronchiolitis obliterans was increased airflow resistance, implying that their lung function had been affected. Even after the patients were treated, they were still affected by the condition, indicating that this condition could be long-lasting. The diagnosis and treatment of bronchiolitis obliterans deserve more attention. If we are to effectively treat this new condition, we need to develop new treatment strategies and new treatments at the same time.
There are few clinical trials in the literature that have involved Fio2 in the treatment of post-thoracotomy patients with acute pulmonary edema. We highlight these trials by discussing their design and results, the rationale for their use of Fio2, the use of Fio2 in post-thoracotomy patients and the benefits and risks, and the lack of evidence to support the use of Fio2 in post-thoracotomy patients with acute pulmonary edema. Results from a recent clinical trial demonstrate that Fio2 is not suitable as a monotherapy in patients with post-thoracotomy pulmonary edema and may increase oxygen desaturation.
Most patients with severe COPD have evidence of lung injury, which is likely due to chronic inflammation and remodeling. There were higher levels of total and high-mobility group-1 protein in BAL fluid in patients with more severe chronic airflow obstruction but not in patients with less severe COPD.