总结

Persistent pulmonary infiltrate results when a substance denser than air (e.g., pus, oedema, blood, surfactant, protein, or cells) lingers within the lung parenchyma. Non-resolving and slowly resolving pneumonias are the most common broad categories of persistent pulmonary infiltrate. [1] [2] [3] Persistence is attributed to defects in host immune defence mechanisms, presence of unusual or resistant organisms, or diseases that mimic pneumonia. [4] [5] [6] Causes of non-resolving pneumoniaFrom the collection of Athanasia Pataka, MD

Classification

The classification of these disorders may become quite complex, as some clinicians focus primarily on the radiological abnormalities, while others emphasise the accompanying clinical features. Non-resolving or slowly resolving pneumonia is loosely defined as a pneumonia that does not improve clinically, or even worsens, despite a minimum of 10 days of adequate antibiotic therapy, or as radiographic infiltrate that does not resolve within 12 weeks. [7] [8] Slowly resolving pneumonias are usually defined as the persistence of radiographic infiltrate in a clinically improved patient for longer than 4 weeks (<50% resolution in 1 month). [9] [10] [11] [12]

A waiting period of 12 to 14 weeks is suggested for slowly resolving pneumonia to be considered non-resolving (or chronic) in older patients with non-tuberculous bacterial pneumonia. [7] Non-responding pneumonia is an inadequate clinical response despite antibiotic treatment. It is an independent risk factor for death and delayed resolution of pulmonary infiltrate. [13] [14] Non-infectious causes are responsible for about 20% of cases of non-resolving pneumonia. [13]

Therapeutic response

A good clinical response to pulmonary infiltrate is defined as 50% clearing of chest radiographic findings at 4 weeks of therapy. [7] Clinical improvement and resolution of leukocytosis supports the conclusion that the patient has responded to antibiotic therapy, even when chest radiographic abnormalities persist. [4] [14] In the case of pneumonia, most patients have a normal temperature and decreased cough within 3 to 5 days after beginning treatment. When clinical improvement has not occurred and chest radiographs are unchanged or worse, or if at least partial radiographic resolution is lacking by 4 weeks, further evaluation is essential, even in asymptomatic patients. [2] [11] [15]

Variant response

Resolution of non-resolving pneumonias varies and depends on the causal agent, the severity of disease, and host factors. [5] [7] Several risk factors may hinder the rate of radiographic clearing of the condition:

• Age >60 years: radiographic clearance of pneumonic infiltrate on completion of antibiotic therapy decreases by 20% per decade after the age of 20 years [2] [16]

• Malnutrition

• Comorbid conditions (COPD, cardiac failure, diabetes, renal failure, immunodeficiency, alcohol intake, smoking, occupational exposure, cancer, cancer treatment, systemic illness): patients with haematological malignancies, immunosuppressive disorders, or exposure to silica, aluminium, or titanium dust are prone to persistent pulmonary infiltrate

• Causal micro-organism

• Initial severity of the infection

• Delay in initiation of therapy.