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Time course of lung function changes in atypical pneumonia
Abstract:
We measured pulmonary function in each of 21 patients suffering from "atypical", non-bacterial pneumonia during the acute illness and during convalescence (two to 18 months) to study the course and the nature of functional impairment at different stages of the disease. In six patients, no aetiological agent was found. An aetiological agent was identified in 15 of the patients: Mycoplasma pneumoniae (seven patients), influenza A (three patients), parainfluenza 3 (one patient), varicella (two patients), Q fever (one patient), coxsackie B3 (one patient). At the time of admission we observed a restrictive pattern in 52%, an obstructive pattern (decreased FEV1/FVC ratio) in 52% abnormalities in distribution of ventilation (abnormal slope of phase 3) in 63%, and abnormalities in gas exchange (increased AaDO2) in 75% of the patients. The frequency of abnormalities in these pulmonary function tests decreased dramatically after two to four weeks and nearly disappeared in most patients during convalescence. The only major residual abnormality was a decreased FEV1/FVC ratio in five subjects, four of whom were smokers. However, when MMEF and V75 were measured at this stage, their average value for all the groups of patients with the exclusion of the Mycoplasma pneumoniae group, was markedly reduced. These data suggest that small airways involvement can be demonstrated during the convalescence of patients recovering from various types of atypical pneumonia other than those caused by Mycoplasma pneumoniae.
Insights
Pulmonary function tests reveal significant impairment in atypical pneumonia patients. Residual small airway dysfunction is noted during convalescence, particularly in non-Mycoplasma pneumoniae cases.
Area of Science:
- Pulmonary Medicine
- Infectious Diseases
- Respiratory Physiology
Background:
- Atypical pneumonia, often non-bacterial, can cause significant pulmonary impairment.
- Understanding the long-term functional consequences of various atypical pneumonia etiologies is crucial for patient management.
Purpose of the Study:
- To investigate the course and nature of pulmonary function impairment in patients with atypical pneumonia during acute illness and convalescence.
- To identify specific patterns of functional deficits and their persistence over time.
Main Methods:
- Pulmonary function tests were conducted on 21 patients with atypical pneumonia during acute illness and convalescence (2-18 months).
- Etiological agents were identified, including Mycoplasma pneumoniae, influenza A, and others.
- Tests included spirometry (FEV1/FVC ratio), ventilation distribution (phase 3 slope), and gas exchange (AaDO2).
Main Results:
- During acute illness, patients exhibited restrictive patterns (52%), obstructive patterns (52%), ventilation distribution abnormalities (63%), and gas exchange issues (75%).
- Pulmonary function abnormalities significantly decreased within weeks and mostly resolved during convalescence.
- Residual decreased FEV1/FVC ratio was observed in 5 subjects (4 smokers).
- Markedly reduced MMEF and V75 values during convalescence suggested small airway involvement in non-Mycoplasma pneumoniae cases.
Conclusions:
- Atypical pneumonia causes transient but significant pulmonary function impairment.
- Small airway involvement may persist during convalescence in patients recovering from atypical pneumonias, excluding Mycoplasma pneumoniae infections.