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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 3  |  Issue : 1  |  Page : 53-56

Evaluation of pulmonary hypertension in stable chronic obstructive pulmonary disease patients using transthoracic echocardiography


1 Department of Pulmonary Medicine, Adesh Institute of Medical Sciences and Research, Bathinda, Punjab, India
2 Department of Pulmonary Medicine, Dr. S.N. Medical College, Jodhpur, Rajasthan, India
3 Department of Pathology, Dr. S.N. Medical College, Jodhpur, Rajasthan, India

Date of Submission08-Dec-2018
Date of Decision19-Jan-2019
Date of Acceptance26-Jan-2019
Date of Web Publication13-Mar-2019

Correspondence Address:
Dr. Swetabh Purohit
Department of Pulmonary Medicine, B2 401, Adesh University Campus, Barnala Road, Bathinda, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/bbrj.bbrj_4_19

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  Abstract 


Background: Pulmonary hypertension (PH) frequently complicates chronic obstructive pulmonary disease (COPD) process and adversely affects the exercise capacity of such patients. However, majority of the COPD patients are not routinely evaluated for PH even though a rapid screening tool in the form of transthoracic echocardiography (TTE) is available for the early diagnosis of PH. This study was conducted with an aim to study the frequency and severity of PH among stable COPD patients. Materials and Methods: Fifty stable COPD patients who met the inclusion criteria were selected and staged for severity by spirometry and screened for PH using TTE. Tricuspid regurgitation jet velocity obtained was used to calculate systolic pulmonary artery pressure (sPAP). Mean pulmonary artery pressure was calculated from sPAP using Chemla formula. Results: (1) The frequency of PH in COPD patients was 48% (24 out of 50). The frequency of PH in patients of mild, moderate, severe, and very severe GOLD COPD stages was 12.5% (1/8), 45.83% (11/24), 61.53% (8/13), and 80% (4/5), respectively. (2) Out of the 24 patients with PH, the relative incidence of mild (25–35 mmHg), moderate (35–45 mmHg), and severe (>45 mmHg) PH was 54.16% (13/24), 29.16% (7/24), and 16.67% (4/24), respectively. Only one patient had “out-of-proportion” PH. Conclusion: PH is an underdiagnosed entity that frequently complicates the course of disease in COPD patients and adversely affects exercise capacity. TTE is an accurate, noninvasive screening tool for PH and should be routinely used in all COPD patients for early diagnosis of PH.

Keywords: Chronic obstructive pulmonary disease, echocardiography, pulmonary hypertension


How to cite this article:
Purohit S, Garg A, Joshi V, Purohit G, Joshee V. Evaluation of pulmonary hypertension in stable chronic obstructive pulmonary disease patients using transthoracic echocardiography. Biomed Biotechnol Res J 2019;3:53-6

How to cite this URL:
Purohit S, Garg A, Joshi V, Purohit G, Joshee V. Evaluation of pulmonary hypertension in stable chronic obstructive pulmonary disease patients using transthoracic echocardiography. Biomed Biotechnol Res J [serial online] 2019 [cited 2019 Jul 22];3:53-6. Available from: http://www.bmbtrj.org/text.asp?2019/3/1/53/254103




  Introduction Top


Chronic obstructive pulmonary disease (COPD) alone stands as a single most important chronic respiratory illness in the elderly that hampers the life of those suffering from the disease significantly. According to the Global Burden of Disease Study, COPD was the sixth leading cause of death in 1990 AD and is expected to climb up to the third spot in 2020 AD. In India, COPD is the second most common pulmonary pathology after pulmonary tuberculosis. Several diseases complicate the course of disease process in COPD patients, but cardiovascular disease is probably both the most frequent and most important comorbidity coexistent with COPD.[1]

Pulmonary hypertension (PH), defined by the European Respiratory Society (ERS) as a hemodynamic and pathophysiological condition associated with an increase in mean pulmonary artery pressure (mPAP) ≥25 mmHg at rest as assessed by right heart catheterization (RHC), is a well-recognized complication of COPD. The prevalence of PH in patients with COPD has not been accurately measured in large epidemiologic studies. When measured by RHC, PH has been found in 20%–90% of COPD patients.[2] In patients with COPD, whether mild or more severe, the presence of PH is associated with an increase in hospitalization and a poorer prognosis.[3] Clinical symptoms and physical signs of PH may be difficult to identify in patients with COPD. Echocardiography is the best screening tool for the assessment of PH. Many studies have confirmed that echocardiographically derived estimates of PAP correlate closely with pressures measured by right heart catheter (r > 0.7).[4] However, unfortunately, screening of COPD patients for the evaluation of coexistent PH is not a routine clinical practice. This often results in delay in the diagnosis of PH in COPD patients. Therefore, the present study was undertaken with the following aims and objectives:

  1. To find out the frequency and severity of PH in patients with COPD
  2. To find out the correlation between the severity of PH and the severity of COPD using GOLD guidelines.



  Materials and Methods Top


This was a cross-sectional descriptive type of study conducted from August 2012 to September 2013 in Kamla Nehru Chest Hospital, Dr. S.N. Medical College, Jodhpur, a tertiary care center for respiratory diseases in the western part of Rajasthan. A total of 78 stable COPD patients who fulfilled the inclusion criteria were examined during the course of this study after taking written informed consent. Twenty-eight patients were excluded as they did not meet the required inclusion criteria. A total of fifty COPD patients confirmed by clinical history, radiology of chest, and spirometry were included in the study. During selection, patients with a history of chronic lung disease other than COPD, hypertension, any primary cardiac disease, any systemic disease that can cause PH, poor echo window, and patients who were unable to perform spirometry were excluded from the study. After a detailed clinical history and thorough physical examination, the patients underwent a battery of tests comprising: complete blood count with hematocrit, renal function test (serum creatinine and blood urea), liver function test (serum glutamic oxaloacetic transaminase, serum glutamic-pyruvic transaminase, serum bilirubin-direct and indirect), thyroid function test, blood sugar, HIV serology testing, skiagram chest posteroanterior view, electrocardiography (on Schiller AT-1 machine), and sputum smear for acid-fast bacilli. All the patients were investigated by spirometry (using RMS Medspiror system) and diagnosed and classified according to the GOLD guidelines (postbronchodilator forced expiratory volume 1 [FEV1]/forced vital capacity ratio <70% predicted) into mild (FEV1 ≥80% of predicted), moderate (50% ≤ FEV1 <80% predicted), severe (30%≤ FEV1 <50% predicted), and very severe (FEV1 <30% predicted). The study was approved by institutional ethics committee wide letter no. F2/Estt/MC/JU/2012/1098 dated 12/11/12.

All patients were subjected to resting two-dimensional transthoracic Doppler echocardiography in the cardiology department of Dr. S.N. Medical College and associated hospitals by expert cardiologists. The machine used was VIVID E9 model of GE health-care system with a multifrequency probe with a range of 2–4.3 MHz.

Tricuspid regurgitant flow was identified by color flow Doppler technique, and the maximum jet velocity was measured by continuous wave Doppler without the use of intravenous contrast. Right ventricular systolic pressure was estimated based on the modified Bernoulli equation and was considered to be equal to the sPAP in the absence of right ventricular outflow obstruction: sPAP (mmHg) = right ventricular systolic pressure = transtricuspid pressure gradient + right atrial pressure (RAP), where transtricuspid gradient is 4v2 (v = peak velocity of tricuspid regurgitation, m/s).[5],[6] RAP was empirically estimated as 15 mmHg before 1997. Since 1997, RAP was estimated to be 5, 10, or 15 mmHg based on the variation in the size of inferior vena cava with inspiration as follows: complete collapse, RAP = 5 mmHg; partial collapse, RAP = 10 mmHg; and no collapse, RAP = 15 mmHg.[7] mPAP from pulmonary artery systolic pressure was calculated using the Chemla formula as follows:[8]

mPAP = 0.61 × sPAP + 2 mmHg.

PH was defined in this study as mPAP ≥25 mmHg. This value was chosen according to the definition of PH (ERS 2009). PH was classified into mild, moderate, and severe categories as mPAP 25–35, 35–45, and >45 mmHg, respectively.[7]


  Results Top


A total of fifty patients were included in the study. The majority of patients in this study were elderly as 70% of patients were in the age group of 51–70 years [Table 1]. There was a male predominance as 96% of the study patients were male [Table 1]. Majority of the patients (74%) had body mass index (BMI) in the normal range of 18.5–24.9 kg/m2, whereas 26% of cases had BMI <18.5 kg/m2 (i.e., malnourished patients) [Table 1]. Majority (96%) of the cases were either current or exsmokers; 4% of the cases were nonsmoking females [Table 1]. Of the smoker patients, 37.5% of cases smoked 40–60 pack-years, whereas 33.33% of cases and 29.16% of cases smoked 60–80 and 20–40 pack-years, respectively [Table 1]. Patients were assessed by spirometry, and the majority of the study patients had moderate-to-severe obstruction (74% cases), while 16% of cases were found to have mild stage of COPD. Very severe obstruction was seen in 10% of cases [Table 2]. The patients were screened for PH using two-dimensional echocardiography [Table 3]. Nearly 46% of cases (23) did not show any abnormality in their echocardiography. Tricuspid regurgitation was seen in 54% of cases. PH was seen in 48% (24) of cases. The frequency of PH in COPD patients was 48% (24/50). Out of the 24 patients with PH, the relative incidence of mild (25–35 mmHg), moderate (35–45 mmHg), and severe (>45 mmHg) PH was 54.16% (13/24), 29.16% (7/24), and 16.67% (4/24), respectively [Table 4]. The frequency of PH in patients of mild, moderate, severe, and very severe GOLD COPD stages was 12.5% (1/8), 45.83% (11/24), 61.53% (8/13), and 80% (4/5), respectively, i.e., as the severity of airway obstruction increased, the frequency of PH also increased [Table 5].
Table 1: Age, gender, body mass index, and smoking pattern of the study population (n=50)

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Table 2: Global Initiative for Chronic Obstructive Lung Disease staging of chronic obstructive pulmonary disease in the study population

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Table 3: Echocardiographic findings in the study population

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Table 4: Severity of pulmonary hypertension in the study population

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Table 5: Frequency and severity of pulmonary hypertension in various chronic obstructive pulmonary disease stages

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PH in COPD patients was predominantly found to be of mild-to-moderate severity. Only one patient had “out-of-proportion” PH. This patient with moderate airflow obstruction had severe PH (>45 mmHg) in the absence of any other cause that could explain the severity of PH [Table 5].


  Discussion Top


A majority of patients were in the age group of 51–70 years (70%). Similar observations were made in studies by Andersen et al.[9] Majority of the study patients were male (96%). This was probably due to high frequency of male COPD patients attending outdoor and indoor facilities of our hospital. Majority of the patients (74%) had BMI in the normal range of 18.5–24.9 kg/m2, whereas 26% of cases had BMI < 18.5 kg/m2 (i.e., malnourished patients). None of the study patients had BMI > 25 kg/m2. As COPD often develops in long-time smokers in middle age, patients also have significant extrapulmonary (systemic) effects including weight loss, nutritional abnormalities, and skeletal muscle dysfunction, leading to lower BMI in COPD patients. More than 90% of the patients were smokers, with a smoking history of 20–60 pack-years, emphasizing the fact that tobacco smoking is the most potent risk factor resulting in the development of COPD. Studies by Jindal et al.[10],[11] support this observation.

Spirometry of the study patients was performed on RMS Medspiror system to classify patients into various GOLD COPD stages. According to GOLD stage of severity, majority (74% patients) of the patients were suffering from moderate-to-severe COPD, highlighting the fact that COPD patients often seek medical care late, when they become breathless on exertion.

Transthoracic echocardiography (TTE) was performed to noninvasively evaluate sPAP in the study patients. Previous studies have shown that TTE can be successfully used to evaluate sPAP in 26%–66% cases of COPD with PH.[4],[12] In the present study, the echocardiographic findings were normal in 23 out of the 50 patients, i.e. 46%: tricuspid regurgitation was seen in 27 cases out of which PH was seen in 24 cases, i.e. 48%. Similar observations were made in the studies of Minai et al.[13] and Andersen et al.[9]

Of the 24 cases with PH, 13 cases (54.16%) had mild PH, 7 cases (29.16%) had moderate PH, and 4 cases (16.67%) had severe PH. Similar results were also reported by Gupta et al.[7] and Oswald-Mammosser et al.[14] In the present study, the frequency of PH in mild, moderate, severe, and very severe COPD was 1/8 (12.5%), 11/24 (45.83%), 8/13 (61.5%), and 4/5 (80%), respectively. This suggests that the frequency of occurrence of PH increased with the increase in the severity of airflow obstruction in COPD patients. Similar results were reported by Gupta et al.[7]

In the present study, there was one patient with moderate airflow obstruction in which severe PH was observed and no other cause to account for the severity of PH. This patient had “out-of-proportion” PH. This may be due to increased vasoconstrictor response to hypoxia or the possible presence of intrinsic pulmonary vascular disease in a patient (independently) who also had COPD. Similar results were observed in studies by Thabut et al.[15] and Gologanu et al.[16]

In our study, it was also observed that, with the exception of one case that had “out-of-proportion” PH, severe PH was found only in severe or very severe COPD cases. The frequency of PH was directly proportional to the severity of disease. Previous studies by Thabut et al.[15] and Gupta et al.[7] showed that the frequencies of severe PH in COPD range from about 1% to 4.7%, but in our study, the frequency of severe PH in COPD was found to be 8% (4/50). This could be explained by the fact that the present study was performed in a small study population comprising of more percentage of severe and very severe COPD patients. The mPAP in patients with mild, moderate, severe, and very severe COPD was 34.6 ± o, 33.33 ± 9.20, 35.54 ± 5.24, and 52.32 ± 10.41 mmHg, respectively.


  Conclusion Top


PH is an underdiagnosed entity that frequently complicates the course of disease in COPD patients and adversely affects exercise capacity. TTE is an accurate, noninvasive screening tool for PH and should be routinely used in all COPD patients for early diagnosis of PH.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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[PUBMED]  [Full text]  
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Andersen KH, Iversen M, Kjaergaard J, Mortensen J, Nielsen-Kudsk JE, Bendstrup E, et al. Prevalence, predictors, and survival in pulmonary hypertension related to end-stage chronic obstructive pulmonary disease. J Heart Lung Transplant 2012;31:373-80.  Back to cited text no. 9
    
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Jindal SK, Aggarwal AN, Gupta D. A review of population studies from India to estimate national burden of chronic obstructive pulmonary disease and its association with smoking. Indian J Chest Dis Allied Sci 2001;43:139-47.  Back to cited text no. 10
    
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Jindal SK, Aggarwal AN, Chaudhry K, Chhabra SK, D'Souza GA, Gupta D, et al. Amulticentric study on epidemiology of chronic obstructive pulmonary disease and its relationship with tobacco smoking and environmental tobacco smoke exposure. Indian J Chest Dis Allied Sci 2006;48:23-9.  Back to cited text no. 11
    
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Tramarin R, Torbicki A, Marchandise B, Laaban JP, Morpurgo M. Doppler echocardiographic evaluation of pulmonary artery pressure in chronic obstructive pulmonary disease. A European multicentre study. Working group on noninvasive evaluation of pulmonary artery pressure. European office of the World Health Organization, Copenhagen. Eur Heart J 1991;12:103-11.  Back to cited text no. 12
    
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Minai OA, Fessler H, Stoller JK, Criner GJ, Scharf SM, Meli Y, et al. Clinical characteristics and prediction of pulmonary hypertension in severe emphysema. Respir Med 2014;108:482-90.  Back to cited text no. 13
    
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Oswald-Mammosser M, Weitzenblum E, Quoix E, Moser G, Chaouat A, Charpentier C, et al. Prognostic factors in COPD patients receiving long-term oxygen therapy. Importance of pulmonary artery pressure. Chest 1995;107:1193-8.  Back to cited text no. 14
    
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Thabut G, Dauriat G, Stern JB, Logeart D, Lévy A, Marrash-Chahla R, et al. Pulmonary hemodynamics in advanced COPD candidates for lung volume reduction surgery or lung transplantation. Chest 2005;127:1531-6.  Back to cited text no. 15
    
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Gologanu D, Stanescu C, Ursica T, Balea MI, Ionita D, Bogdan MA, et al. Prevalence and characteristics of pulmonary hypertension associated with COPD – A pilot study in patients referred to a pulmonary rehabilitation program clinic. Maedica (Buchar) 2013;8:243-8.  Back to cited text no. 16
    



 
 
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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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