Pulmonary function tests in children with beta-thalassemia major

Pulmonary function in patients with transfusion-dependent thalassemia and its associations with iron overload

In patients with transfusion-dependent thalassemia (TDT), pulmonary function impairment has been reported but data are conflicting. Moreover, it remains unclear whether pulmonary dysfunction is associated with iron overload. This study aimed to evaluate the pulmonary function in patients with TDT and to investigate the associations between pulmonary dysfunction and iron overload. It was a retrospective observational study. 101 patients with TDT were recruited for lung function tests. The most recent ferritin levels (pmol/L) and the magnetic resonance imaging (MRI) measurements of the myocardial and liver iron status, as measured by heart and liver T2* relaxation time (millisecond, ms) respectively, were retrieved from the computerized medical records. Only data within 12 months from the lung function measurement were included in the analysis. The serum ferritin, and the cardiac and liver T2* relaxation time were the surrogate indexes of body iron content. The threshold of abnormality in lung function was defined as under 80% of the predicted value. 101 subjects were recruited with a mean age of 25.1 years (standard deviation (SD) 7.9 years). Thirty-eight (38%) and five (5%) demonstrated restrictive and obstructive lung function deficits, respectively. A weak correlation of FVC %Predicted and TLC %Predicted with MRI myocardial T2* relaxation time (rho = 0.32, p = 0.03 and rho = 0.33, p = 0.03 respectively) was observed. By logistic regression, MRI cardiac T2* relaxation time was negatively associated with restrictive lung function deficit (B - 0.06; SE 0.03; Odds ratio 0.94; 95% confidence interval (CI) 0.89-0.99; p = 0.023) after adjusting for age, sex and body mass index. Restrictive pulmonary function deficit was commonly observed in patients with TDT, and the severity potentially correlates with myocardial iron content. Monitoring of lung function in this group of patients, particularly for those with iron overload, is important.

Pulmonary functions in Egyptian children with transfusion-dependent β-thalassemia

BACKGROUND

In β-thalassemia, there are varying degrees of ineffective haematopoiesis, intermittent haemolysis and iron overload. Excess iron is deposited in organs such as the heart, the liver, the endocrine glands and the lungs.

OBJECTIVES

To evaluate the pulmonary functions in asymptomatic beta thalassemic children on regular transfusion therapy and their relation to iron overload.

METHODS

The study included 50 transfusion-dependent β-thalassemic children and 50 apparently healthy children as control. All children had undergone pulmonary function tests (spirometry, lung volumes and diffusion capacities). In addition, test to determine the mean serum ferritin of the last 2 years and pre-transfusion haemoglobin and chest radiograph and echocardiography were performed for the thalassemic children only.

RESULTS

A total of 70% of the thalassemic children had diffusion impairment, whereas 34% of them had associated restrictive abnormality. Thalassemic children with serum ferritin >2500 ng mL^-1 had significantly lower values of forced vital capacity (FVC), forced expiratory volume at one second (FEV1), peak expiratory flow (PEFR), total lung capacity (TLC) and diffusing capacity of carbon monoxide (DLCO) (P < 0·05). Only diffusion impairment had a significant positive correlation with serum ferritin level. Restrictive impairment had significant positive correlations with age, duration of blood transfusion and serum ferritin level and a significant negative correlation with duration of chelation (P < 0·05). Having a serum ferritin >2500 ng mL^-1 was the only predicting factor for diffusion impairment and the strongest predicting factor for restrictive dysfunction.

CONCLUSION

Despite being asymptomatic, the majority of thalassemic children in this study suffered from diffusion impairment either alone or in combination with restrictive dysfunction. These pulmonary dysfunctions correlated significantly with body iron stores measured by serum ferritin.

How I treat hypoxia in adults with hemoglobinopathies and hemolytic disorders

Hemoglobinopathies are caused by genetic mutations that result in abnormal hemoglobin molecules, resulting in hemolytic anemia. Chronic complications involving the lung parenchyma, vasculature, and cardiac function in hemoglobinopathies result in impaired gas exchange, resulting in tissue hypoxia. Hypoxia is defined as the deficiency in the amount of oxygen reaching the tissues of the body and is prevalent in patients with hemoglobinopathies, and its cause is often multifactorial. Chronic hypoxia in hemoglobinopathies is often a sign of disease severity and is associated with increased morbidity and mortality. Therefore, a thorough understanding of the pathophysiology of hypoxia in these disease processes is important in order to appropriately treat the underlying cause and prevent complications. In this article, we discuss management of hypoxia based on three different cases: sickle cell disease, β-thalassemia, and hereditary spherocytosis. These cases are used to review the current understanding of the disease pathophysiology, demonstrate the importance of a thorough clinical history and physical examination, explore diagnostic pathways, and review the current management.

Pulmonary dysfunction in thalassaemia major: is there any relationship with body iron stores?

Although pulmonary function abnormalities in thalassaemia major (TM) were described in 1980, the pathogenetic mechanism is not clear and data are contradictory, probably because of study heterogeneity and the multifactorial nature of the pathogenesis. We retrospectively analysed 73 adult TM patients to evaluate the prevalence of pulmonary dysfunction in adult TM and investigate relationships with iron load. All patients underwent body plethysmography and carbon monoxide diffusion (DLCO) was assessed in 63, in addition to blood tests, echocardiogram and T2* myocardial and liver magnetic resonance imaging. Restrictive lung disease was present in 26 (35·6%) patients. Serum ferritin levels were higher in patients with restrictive pattern (1526 μg/l vs. 975 μg/l, P = 0·05). Restrictive lung disease did not correlate with cardiac or liver iron overload. However, considering only patients with serum ferritin >2500 μg/l, those with restrictive pattern also had heart (T2* 14·28 ± 9·99 ms vs. 31·59 ± 7·43 ms) and liver iron overload (LIC 16·02 ± 8·44 mg vs. 5·02 ± 2·69 mg Fe/g dry weight) compared to those without restrictive pattern. Twenty-five patients (39·7%) had decreased DLCO. No correlation was observed with iron parameters. In our data restrictive pattern was predominant; we observed a relationship with serum ferritin levels suggesting that iron, particularly its chronic effect, could play a role in the pathogenesis of pulmonary disease.

Pulmonary hypertension associated with thalassemia syndromes

Chronic hemolytic anemia has increasingly been identified as an important risk factor for the development of pulmonary hypertension (PH). Within the thalassemia syndromes, there are multiple mechanisms, both distinct and overlapping, by which PH develops and that differ among β-thalassemia major or intermedia patients. PH in β-thalassemia major correlates with the severity of hemolysis, yet in patients whose disease is well treated with chronic transfusion therapy, the development of PH can be related to cardiac dysfunction and the subsequent toxic effects of iron overload rather than hemolysis. β-Thalassemia intermedia, on the other hand, has a higher incidence of PH owing to the low level of hemolysis that exists over years without the requirement for frequent transfusions, while splenectomy is shown to play an important role in both types. Standard therapies such as chronic transfusion have been shown to mitigate PH, and appropriate chelation therapy can avoid the toxic effects of iron overload, yet is not indicated in many patients. Limited evidence exists for the use of pulmonary vasodilators or other therapies, such as l-carnitine, to treat PH associated with thalassemia. Here, we review the most recent findings regarding the pathogenic mechanisms, epidemiology, presentation, diagnosis, and treatment of PH in thalassemia syndromes.

Pulmonary Functions in Children With Thalassemia Major

BACKGROUND

Thalassemia major (TM) is a chronic disease requiring regular transfusions that may result in generalized iron loading, such as in the heart, the liver, endocrine organs, and the lungs. We aimed to determine pulmonary function abnormalities in children with TM in our center.

PATIENTS AND METHODS

In this study, pulmonary function tests (PFTs) of 49 patients with TM who received regular blood transfusion and had no history of chronic respiratory disease were evaluated. The relationship between PFTs and the age, the body surface area, pretransfusional hemoglobin, and serum ferritin was evaluated.

RESULTS

Among the β-TM patients included in this study, 61% were male and 39% were female, with a mean age of 10.8±3 years (range, 5 to 17 y). The patients' mean level of ferritin was 3873±2011 ng/dL (range, 676 to 9476 ng/dL). A reduced forced vital capacity (FVC) was found in 33 patients (67%). A reduced forced expiratory volume in 1 second (FEV1) was found in 15 patients (30%). A forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) ratio of >80% was found in all patients. The peak expiratory flow (PEF) was decreased in 23 patients (46.9%). The forced mid-expiratory flow between 25% and 75% of the exhaled vital capacity (MEF25%-75%) was decreased in 5 patients (10%). FVC and FEV1 values in patients with a high ferritin level (>2500 ng/dL) were decreased compared with patients with a low ferritin level (<2500 ng/dL) (P=0.04, 0.03). FVC, FEV1, and PEF parameters were negatively correlated with the age and the body surface area. Age was a predictor of FVC (β=-0.450, P<0.001), FEV1 (β=-0.419, P<0.001), and PEF (β=-0.505, P<0.001), and hemoglobin was a predictor of FEV1/FVC (β=0.366, P=0.01) and MEF25%-75% (β=0.323, P=0.003).

CONCLUSIONS

Our results concluded that the respiratory system should be evaluated by PFTs even in asymptomatic patients with high serum ferritin levels during the adolescent period annually to prevent the squeal of pulmonary disease in TM. Patients who have abnormal PFTs should be reevaluated for compliance with chelation therapy and the transfusion program.

Effect of using bedside leukocyte filter on pulmonary functions in patients with thalassemia major

In settings of limited health resources, using leukocyte-filtered blood is limited to patients with leukocyte-mediated complications. The aim of this study was to determine the patterns of lung dysfunction among patients with β-thalassemia major (BTM) after the application of the leukostop filter during transfusion for a period of 6 months. The study included 30 patients with transfusion-dependent BTM divided into two groups according to the use of leukocyte filter. Group I included 15 patients with BTM allocated to use the leukocyte filter before each blood transfusion for 6 months and group II included 15 patients with BTM using nonleukocyte-filtered blood. Patients with history of airway disease and smokers were excluded. Chest X-ray and pulmonary function tests (PFT) using spirometry were done for each patient at baseline and after the use of the leukocyte filter for 6 months. No significant difference was found at baseline PFTs in both groups, the distribution of obstructive pulmonary disease significantly improved in group I in the postfilter evaluation, P < 0.05, however no change in pulmonary disease distribution in group II. A statistical significance improvement in forced vital capacity (FVC), forced expiratory volume in 1st second (FEV1) and FEV1/FVC in postfilter evaluation, while in group II a decline in FEV1, FVC, and no significant change in FEV1/FVC ratio. There was no correlation between serum ferritin and PFT results.

CONCLUSION

Pulmonary function abnormalities, although subclinical is not an infrequent finding in patients with BTM; leukofiltred blood may improve PFT.

Cardiac and pulmonary dysfunction in asymptomatic beta-thalassanemia major

This study assessed cardiac and pulmonary dysfunction in 26 asymptomatic patients with beta-thalassemia major. This investigation was a case-controlled study considering 10-20-year-old patients with beta-thalassemia major and no cardiac or pulmonary symptoms. Healthy individuals matched for age and sex were used as controls. At 48-72 h after blood transfusion, the patients underwent echocardiography and spirometry by a cardiologist and a pulmonologist. The results were compared to those of the control group. The right and left myocardial performance index, preejection period/ejection time ratio, ejection fraction, acceleration time, isovolumic contraction time, and bilateral isovolumic relaxation times in the study group demonstrated significant differences from the data of the controls. Right deceleration time was significantly different between the 2 groups. Myocardial performance index, peak early velocity of the right heart, and peak atrial velocity-to-peak early velocity ratio of the right side by Doppler tissue imaging were also significantly different between the 2 groups. Spirometry showed a significant difference in forced expiratory volume in 1 s/forced vital capacity between groups. Based on spirometry, pulmonary involvement in the patients was 77% restrictive. These findings show that systolic and diastolic dysfunction of the heart and pulmonary disturbances are unavoidable in patients with beta-thalassemia major.

Restrictive pulmonary dysfunction and its predictors in young patients with β-thalassaemia major

BACKGROUND

Pulmonary dysfunction represents one of the most undervalued and less recognized complications in patients with β-thalassaemia.

OBJECTIVES

The aim of this study was to assess the pattern of pulmonary dysfunction and consequently to investigate possible associated factors that might contribute to lung impairment in young patients with β-thalassaemia major.

METHODS

Fifty-two children and young adults (mean age: 21.33 ± 6.24 years) with β-thalassaemia major on conventional treatment (transfusions and iron chelation therapy) were included in the study. A complete computerized pulmonary function testing (PFT) system for recording pulmonary diffusion capacity and simultaneous determination of alveolar volume and pulmonary volumes was equipped.

RESULTS

Results showed that 20 patients (38.46%) had restrictive pulmonary pattern that was preferentially observed in older and shorter patients. Serum ferritin levels were higher in the restrictive group (2,096 ± 1,831 ng/dl) compared to patients with normal pulmonary function (1,354 ± 942 ng/dl) (P = 0.066). Diffusional impairment characterized by significantly lower DLCO*% values, was observed in the restrictive group (P = 0.004), implicating the 62.5% of the population studied. Paired linear correlations showed that age was negatively correlated to DLCO*% (r = -0.548, P < 0.001) and SaO(2) % (r = -0.789, P < 0.001) and with most of the pulmonary functional parameters that determine a restrictive. Multivariate regression analysis identified age as the major predictor for restrictive pulmonopathy followed by serum ferritin levels.

CONCLUSIONS

Our study shows that pulmonary impairment is shown in a great proportion even among asymptomatic young thalassaemic patients, thus, regular screening of pulmonary function should be adopted in the routine clinical follow up of these patients.

Pulmonary function test in transfusion-dependent beta-thalassemia patients

Beta-thalassaemia is the most common hemoglobinopathies in our region with treatment of regular blood transfusion. Iron overload and hemosiderosis can cause organ involvement. Recent studies have focused on pulmonary involvement and pathophysiology of lung damage. The goal of this study was to investigate the pulmonary abnormalities in thalassemic patients in relation with sign and symptoms and iron overload. The authors studied pulmonary function test (PFT) at the Adult Thalassemia Clinic in Tehran. The history of blood transfusion, iron chelation, respiratory problems, and drug usage was taken. Physical examination, PFT, arterial blood gas (ABG), and chest X-ray (CXR) were done. In total, 139 patients were studied. The mean age was 21.1 years and mean duration of transfusion was 18 years. It was found that 133 patients (95.7%) did not have respiratory problems and only 6 (4.3%) had some respiratory complaints. In CXR, 100 patients (89.3%) had normal lung pattern and others (10.7%) had variable degrees of abnormal lung pattern. In ABG, mean of Po(2) was 73.5% and mean of O(2) saturation was 90.6%. In PFT, 101 patients (72.7%) had restrictive pattern, 35 (25.1%) had normal pattern, and 3 (2.2%) had combined pattern. According to vital capacity, the patients were placed in five categories: 54 patients (38.8%) normal, 37 (26.6%) mild, 35 (25.3%) moderate, 10 (7.2%) severe, and 3 (2.1%) extremely severe pulmonary deficit. There was no statistical significance between PFT results with all variables studied, except duration of blood transfusion, which may be considered a indirect effect of iron load (p = .05, r = .361). According to these results, restrictive pattern was the most common finding (72.7%) in PFT, while 95.7% of patients had no respiratory complaint, and in the chest X-ray group, 89.3% had normal pattern. The authors conclude that the lung may be considered a site for organ damage, and alteration of pulmonary function may be expected in transfusion-dependent patients in spite of no pulmonary symptoms or normal CXR. In recent years, because of new iron chelating drugs, doctors can expect thalassemic patients to have a long life-time and need to increase their quality of life. One way to do this is to evaluate the respiratory system by PFT to prevent the squeal of pulmonary disease.