الفهرس 
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Abstract
Chronic obstructive pulmonary disease (COPD) is a disease of the modern society and is a cause of high morbidity, early mortality and high rate of death and a heavy burden on healthcare systems. COPD is a chronic disease, slowly progressive and is characterized with a chronic inflammation of the bronchi, which in most cases is an irreversible process. By definition, it is a chronic obstruction of the airflow as a combination of inflammation of the bronchi and bronchioles and parenchymal destruction. Anatomic and pathophysiologic close relationship between the respiratory and cardiovascular systems as well as the present risk factors were a great motivation for conducting a thorough research in this field. COPD affects the cardiovascular system, especially the right heart function. Secondary pulmonary hypertension is a common complication of chronic obstructive pulmonary disease with a reported prevalence between 20 to 90%, depending on the criteria used. PH is primarily seen in patients with advanced COPD or patients with severe hypoxaemia with resting PH reported in up to 30% of COPD patients and exercise-induced PH in up to 90% of patients. In the current study, a total of 73 patients with COPD were enrolled. The study aimed to evaluate the entire course of exercise during cardiopulmonary exercise test (CPET) in COPD patients. It was conducted from October, 2019 to December, 2021 in Assiut University Hospital – Chest department and Cardiology department. All patients fulfilled clinical and functional diagnosis according to the GOLD criteria 2021, presenting with post-bronchodilator FEV1/FVC < 0.70. Out of those patients 30 (41.1%) patients hadn’t PH while 43 (58.9%) patients had PH. Based on the degree of PH; out of those 43 patients; 25 (34.2%) patients had mild to moderate PH and 18 (24.7%) patients had severe PH. Baseline data showed no significant differences between both groups. Majority of patients in both groups was malesThe main findings of CPET in the current study were that PH is negatively correlated with exercise capacity, specifically peak VO2 percent predicted. Furthermore, PH had a significant impact on gas exchange. Also, in patients with severe COPD, PH significantly reduces oxygen pulse. Also, we found that patients with severe PH and those with GOLD stage III/IV had more significant impairment in comparison to other groups. The findings show that, in addition to the usual ventilatory and cardiovascular impairments of exercise tolerance in COPD patients, PH reduces oxygen uptake and oxygen pulse at peak exercise and impairs exercise capacity. The decrease in the oxygen pulse, which is the oxygen consumption divided by the heart rate, has been used to estimate stroke volume and thus cardiac function in these patients, suggesting that the effect of PH may be related to cardiac limitation in part. The current study had also found a negative correlation of mean pulmonary artery pressure with predicted VO2 and oxygen pulse. Predictors of PH among COPD patients included in the study were oxygen saturation before the test and oxygen pulse. The pre-test SaO2 at cut off < 91% had 71.3% accuracy for prediction of PH with area under curve was 0.80 while peak oxygen pulse (mL/beat) at cut off point < 6.6 had 78.3% accuracy for prediction of PH with area under curve was 0.82. It was found that predictors for severe PH among patients with COPD in the current study were predicted MVV and predicted VO2. The predicted MVV at cut off < 19 had 71.5% accuracy for prediction of severe PH with area under curve was 0.70 while VO2 (%predicted) at cut off point < 41 had 71.5% accuracy for prediction of severe PH with area under curve was 0.89.ConclusionsCardiopulmonary exercise testing is considered
the gold standard to evaluate the level of exercise capacity
in patients with severe COPD. The research suggests that PHT is relatively common in patients with severe COPD, and it was found that elevated pulmonary artery pressure reduced exercise capacity, which is consistent with previous researches. Also, echocardiography as a non-invasive method with all its modalities has shown superiority in assessing and monitoring of patients with COPD. Echocardiography can give us in a fast and accurate way many parameters in different stages of the disease, which will help in assessment and prognosis of patients with COPD. Recommendations: Because of the relatively high prevalence of PH in severe COPD, CPET may play a role in screening for PH or monitoring patients for the development of PH, as lower than expected exercise performance or a decline in exercise performance without a change in pulmonary function in a COPD patient may indicate PH. In patients with severe COPD, echocardiography is recommended screening tool for assessment of the possibility of development of pulmonary hypertension. Multi centers future studies on large number of patients are recommended to confirm these findings.