IPF patients are limited by mechanical and not pulmonary-vascular factors - results of a derivation-validation cohort study.

BACKGROUND: During cardiopulmonary exercise testing (CPET), Idiopathic Pulmonary Fibrosis (IPF) patients do not reach their direct maximum voluntary ventilation (MVV) and have deranged gas exchange. Their exercise limitation is therefore attributed to a pulmonary vascular mechanism. METHODS: We studied two cohorts (derivation and validation) of IPF patients with lung function testing and CPET. Maximal ventilation at exercise (VEpeak) was compared to direct MVV by Bland-Altman analysis. RESULTS: In the derivation cohort (n = 101), direct MVV over-estimated VEpeak by a factor of 1.51, driven by respiratory rate during MVV that was 1.99 times higher at rest as compared to VEpeak at exercise. The formula (FEV1 × 20.1) + 15.4 was shown to predict VEpeak (r2 = 0.56) in the derivation cohort. In the validation cohort of 78 patients, VEpeak was within a factor of 1.27 (6.8 l/min) of predicted according to the novel formula. According to the novel prediction formula the majority of patients (58%) in the entire cohort have VEpeak within 85% of their predicted MVV, which would indicate a mechanical respiratory limitation to exercise. CONCLUSION: Estimation of direct MVV performed at rest leads to significant over-estimation of the breathing reserve in IPF patients. This may lead to over-diagnosis of pulmonary vascular limitation in these patients. Expected maximal ventilation at exercise may be accurately predicted indirectly by an IPF-specific formula.

Long-term pulmonary function after recovery from pulmonary contusion due to blunt chest trauma.

BACKGROUND: Blunt chest trauma can cause severe acute pulmonary dysfunction due to hemo/pneumothorax, rib fractures and lung contusion. OBJECTIVES: To study the long-term effects on lung function tests after patients' recovery from severe chest trauma. METHODS: We investigated the outcome and lung function tests in 13 patients with severe blunt chest trauma and lung contusion. RESULTS: The study group comprised 9 men and 4 women with an average age of 44.6 +/- 13 years (median 45 years). Ten had been injured in motor vehicle accidents and 3 had fallen from a height. In addition to lung contusion most of them had fractures of more than three ribs and hemo/pneumothorax. Ten patients were treated with chest drains. Mean intensive care unit stay was 11 days (range 0-90) and mechanical ventilation 19 (0-60) days. Ten patients had other concomitant injuries. Mean forced expiratory volume in the first second was 81.2 +/- 15.3%, mean forced vital capacity was 85 +/- 13%, residual volume was 143 +/- 33.4%, total lung capacity was 101 +/- 14% and carbon monoxide diffusion capacity 87 +/- 24. Post-exercise oxygen saturation was normal in all patients (97 +/- 1.5%), and mean oxygen consumption max/kg was 18 +/- 4.3 ml/kg/min (60.2 +/- 15%). FEV1 was significantly lower among smokers (71.1 +/- 12.2 vs. 89.2 +/- 13.6%, P = 0.017). There was a non-significant tendency towards lower FEV1 among patients who underwent mechanical ventilation. CONCLUSIONS: Late after severe trauma involving lung contusion, substantial recovery was demonstrated with improved pulmonary function tests. These results encourage maximal intensive care in these patients. Further larger studies are required to investigate different factors affecting prognosis.