Discussion
hypersensitivity pneumonitis, dyspnea, desaturation, syncope, fatigability, lung disease, hypoxia, chronic lung diseases, lung diseases, fibrosis, palpitation, cough, RV failure, CTEPH, pulmonary hypertension
HYPERSENSITIVITY PNEUMONITIS, PULMONARY FIBROSIS, LUNG DISEASE, HYPOXIA, DISEASE, LUNG DISEASES, FIBROSIS, HYPOXIC, OPACITIES, PULMONARY HYPERTENSION, CHRONIC LUNG DISEASE
The current study included 60 patients with hypersensitivity pneumonitis to assess the predictors and factors associated with pulmonary hypertension in patients with HP.The descriptive data showed that the mean age of patients was 41.67 years which is considered middle age, with a female predominance (88.33%), mostly resident in rural areas (85%), history of raising birds found in (83.33%) and (16.67%) of patients did not show history of exposure to a known causative agent, so it was considered as cryptic HP. These results are matched with the study conducted by Akl et al. in Egypt, in which females were found to be affected ten times more than males with a ratio 10:1, and the mean age of affection was 42.72 years ± 12.54 and most of patients had history of raising birds (78.12%) [Others found no significant sex differences in HP patients, with the mean age was 61.9 years which was older than our patients, with 64% of patients were bird breeders [This may reflect the characteristics of the exposed working population burden [As regards the clinical presentation, all the patients were complaining of cough and dyspnea with different grades (90% of them were between mild and moderate grades) this is consistent with the study conducted by Lima et al. [A smaller percentage of patients (15%), experienced syncope which is uncommon symptom in hypersensitivity pneumonitis, but it may be related to development of pulmonary hypertension. It is used as one of the markers of severity to assess mortality in the first year of diagnosis in PH [HRCT scan findings of the current study population revealed the following patterns; ground glass opacities GGO (100%), Centri-lobular nodules (nodular pattern) (38.33%), Air trapping (mosaic pattern) (38.33%), Fibrotic pattern (23.33%). Similar results were found in El-Kareem et al. study in which the most predominant patterns were isolated GGO or in combination with either nodules or air trapping [The mean arterial oxygen saturation in the study group was 89 ± 11% on resting position and there were exercise desaturation reaching a mean of 83 ± 12%, finding that was consistent with Lima et al. study [This exercise desaturation is explained by the increase in the oxygen demand [The most accessible, most widely used non-invasive tool to screen for pulmonary hypertension (PH) in patients with lung diseases is echocardiography [In the current study PH was considered in 17 patients (28.33%) based on echocardiographic signs and probability of PH (13 patients with intermediate and 4 patients with high probability of PH).Patients were classified into two groups HP with and without PH (based on echocardiographic probability for PH), comparison of both groups revealed that patients with PH showed significant increase in their symptoms mainly dyspnea, syncope, palpitation and easy fatigability. With predominant fibrotic pattern in HRCT chest than other patterns, non significant decrease of 6MWTD, about 82% of them had hypoxia (OThe first research concerned with PH in HP patients was conducted by Koschel et al. it revealed that 19% of patients with fibrotic HP had PH based on estimated PASP > 50 mmHg by echocardiography, This was matched to our results [Another study evaluated the hemodynamics of PH in HP patients by RHC documented PH in 50% of patients with fibrotic HP (mPAP ≥ 25 mmHg) and sever PH (mPAP > 35 mmHg) in only 10%. Patient with PH were significantly hypoxic with reduction of FVC and DLCO and significant desaturation after 6MWD [Walscher et al. found PH in 9.5% of HP patients, but they depend on medical reports only to define PH which was not sufficient [More recent study conducted on 70 patient with HP considered PH diagnosis in 37% of patients based on echocardiography, authors noticed that patient with HP and PH has significant reduction of resting POThe discrepancy of data between studies concerning PH in HP could be explained by differences in patients ҆ age, percentage of patients fibrotic HP and time from disease onset to diagnosis.Regarding predictors of PH, our results revealed that the likelihood of PH increased 62 and 49 time more in HP patients with hypoxia (less than 90%) and fibrotic pattern in CT,even after adjustment for age, sex and bird exposure, the likelihood of PHT still higher in presence of hypoxia and fibrosis in CT, OR = 28 and 17.The development of pulmonary hypertension in chronic lung diseases is multifactorial, the main factor is hypoxic vasoconstriction of pulmonary vessels to shift blood to well ventilated areas to optimize ventilation-perfusion matching, sustained hypoxia promotes intracellular mediators and hypoxia inducible factor 1α (HIF-1α) leading to increase vascular remodeling and increase pulmonary vascular resistance with further increase in pulmonary artery pressure [Dybowska et al. found that fibrotic HP was not a predictor of PH on echocardiogrsphy when they use PASP 36 mmHg as cut off of diagnosis of PH, but PASP > 50 mmHg was exclusively observed in fibrotic HP. So, they declared that role of pulmonary fibrosis as predictor of PH in HP was not clear, which is not in line with our findings [This study had several limitations. First, it is a single centre study with potential selection bias of the patients. Second, small number of the study group and that we depend on the echocardiography signs and probability for diagnosis of pulmonary hypertension and that RHC was performed in 4 cases (high echo probability of PH). But, based on ESC/ERS guidelines, 2015 Potential indications for RHC in advanced lung disease are (1) To confirm diagnosis or exclude PH in candidates for surgical treatments (transplantation, lung volume reduction), (2) If PAH or CTEPH were suspected, (3) RV failure and (4) inaccurate echocardiographic findings in highly suspicious cases with potential therapeutic implications [