Emphysema

  “Pulmonary emphysema is currently defined as a condition of the lung characterized by abnormal, permanent enlargement of the airspaces distal to the terminal bronchiole accompanied by destruction of their walls, without obvious fibrosis>. Emphysema is a phenotypic component of chronic obstructive pulmonary disease (COPD), bearing substantial lung function impairment and poor prognosis. Emphysemic patients feature lower body mass index, less exercise tolerance, and worse quality of life than non-emphysemic ones.” (1)

 

More Than a Respiratory Phenomenon

 

  Emphysema is characterized by dyspnea, chronic coughing and a hampered ability to breath during exercise, strenuous or otherwise. It is a disease with a progressive existence as its symptoms keep worsening as time goes by.

  “Pulmonary emphysema is defined anatomically as enlargement of alveoli with destruction of their walls, and is present to varying degrees in COPD (Chronic obstructive pulmonary disease). Emphysema is reliably quantified in vivo by computed tomography (CT) and correlates with histopathology.

  Emphysema at CT has been shown to predict mortality independent of airflow limitation, suggesting a distinct pathophysiology from non-emphysematous COPD. Emphysema is also associated with impaired pulmonary blood flow, and cardiac filling that is independent of airflow limitation. While emphysema has been shown to predict shorter six-minute walk distance, lower peak O2 uptake and greater exercise ventilatory inefficiency in COPD, the independent contribution of emphysema in COPD to the abnormal physiological and perceptual response to exercise remains poorly understood.” (2)

  The reason emphysema is so scary is that it is difficult to see it coming. During its early stages, emphysema can easily be mistaken by the patient for some transitory or short-lived disease. However, diagnoses usually occurs once the disease has advanced enough for it to be considered irreparable. The patient then experiences flare ups of symptoms and it is here where most that are afflicted seek professional help, when it is too late.

  Besides the above-mentioned symptoms, emphysema can also be accompanied by cyanosis, edema, migraines, exhaustion, weight loss and chronic bronchitis. Chronic bronchitis is diagnosed when sputum (productive cough) is coughed for three months throughout the course of 2 straight years.

  “Early and accurate diagnosis of emphysema is said to be invaluable for identification of clinically silent and mild emphysema. Recently, computed tomography (CT) has been much advocated for its efficacy in detailed diagnosis of emphysema, and the results have been compared with the pathology grade of emphysema in resected lung specimens.” American Review of Respiratory Disease (3)

 

Manifestation of Emphysema

 

  • The patient’s chest resembles the shape of a barrel which results from the lungs becoming enlarged and there is reduced functionality of respiratory muscles.
  • Inspiratory excursion. An uneven motion of the respiratory muscles.
  • Tactile fremitus. This occurs when the chest vibrates when talking.
  • Increased duration of exhalation accompanied by grunt sounds.
  • Wheezing as inhalation is attempted.

 

Physiopathology of Emphysema

 

  “In emphysema, respiratory movements are profoundly affected, due in part to impairment of muscle activity. Both the diaphragm and the intercostal are involved.

  In normal individuals, the action of the diaphragm accounts for the 40 per cent of the vital capacity of the lungs. In ordinary quite breathing, this muscle descends about 1.2 cm, whereas on deep inspiration its excursion may be 3 cm. to 6 cm, depending upon the shape of the chest. In obstructive emphysema, the diaphragm is gradually pushed downwards as the lungs increase in size, so that its action becomes more and more limited.  In advanced cases the position of extreme contraction may be reached, and it then cannot longer function. Under this condition, the intercostal and accessory muscles take on the entire burden of respiration. As they expand the chest, occasionally the diaphragm actually ascends during inspiration as it drawn upwards by the thoracic cage. This paradoxical movement may be distinctly observed under the fluoroscope.

  The intercostal muscles are likewise impaired in obstructive emphysema, for as the chest assumes a barrel shape the ribs separate and the levators of the ribs are distorted.” (4)

As emphysema gets worse, breathing can become difficult even when sedentary, not to mention at the minimal effort towards an active lifestyle. In an attempt to inhale with increased efficacy, some patients will also display a pursing of the mouth during breathing.

 

The Prevalence of Emphysema

 

  “Pulmonary emphysema is a phenotypic component of chronic obstructive pulmonary disease (COPD) which carries substantial morbidity and mortality. We explored the association between emphysema and body height in 726 patients with COPD using computed tomography as the reference diagnostic standard for emphysema. We applied univariate analysis to look for differences between patients with emphysema and those without, and multivariate logistic regression to identify significant predictors of the risk of emphysema. As covariates we included age, sex, body height, body mass index, pack-years of smoking, and forced expiratory volume in one second (FEV1) as percent predicted. The overall prevalence of emphysema was 52%. Emphysemic patients were significantly taller and thinner than non-emphysemic ones, and featured significantly higher pack-years of smoking and lower FEV1 (P < 0.001). The prevalence of emphysema rose linearly by 10-cm increase in body height (r2 = 0.96). In multivariate analysis, the odds of emphysema increased by 5% (95% confidence interval, 3 to 7%) along with one-centimeter increase in body height, and remained unchanged after adjusting for all the potential confounders considered (P < 0.001). The odds of emphysema were not statistically different between males and females. In conclusion, body height is a strong, independent risk factor for emphysema in COPD.” (5)

  UCFS Health affirms that “the goal of therapy for emphysema is to provide relief of symptoms, prevent complications and slow the progression of the disease. Quitting smoking is also essential for patients with emphysema, since continuing to use tobacco will only further damage the lungs.”

  “The prevalence and mortality of chronic obstructive pulmonary disease (COPD) in female smokers is rapidly increasing. Female smokers are more likely than men to report respiratory symptoms and exhibit greater baseline airway responsiveness to methacholine. Indirect evidence suggests that women may be more predisposed to develop smoking-induced lung function impairment and experience greater mortality. Despite these compelling data, COPD continues to be underdiagnosed in women and research into sex differences in advanced COPD remains limited. Using carefully characterized patients from the National Emphysema Treatment Trial (NETT), we hypothesized that differences in disease expression in severe emphysema would be identified between males and females. Specifically, we sought to examine differences in the symptomatic, physiological, radiological, and histological expression of emphysema.” Medicine (6)

 

Things Can Get Complicated

 

  Many complications can arise as a result of emphysema. This disease carries with it a very high rate of mortality. Its complications do not make things any easier and promote early death:

  • Pulmonary Hypertension.
  • Cardiac arrest.
  • Increased incidence of pulmonary infections such as pneumonia.
  • Pneumothorax: This is when there is an increase of air present between the lungs and their corresponding pleural membranes.
  • Respiratory failure.
  • Polycythemia Vera: This happens when there is an exaggerated production of red blood cells to compensate the lack of entering oxygen. The problem with this is that it increases blood thickness and due to the amount of circulating erythrocytes, small capillaries can become jammed.

 

A Difficult But Possible Way to Live

 

  “The question of whether cigarette smoking is a cause of emphysema was raised in the 1950s, and the landmark study by the British epidemiologists Fletcher and Peto supported the concept that chronic cigarette smoking is indeed the major cause of chronic bronchitis and emphysema. More recently, a consensus has begun building that the lung structure is attacked and destroyed by inhaled noxious agents contained in cigarette smoke or in polluted air; the effects of exposure to diesel exhaust, ozone, and microparticles are being examined. There is also agreement that not every long-term heavy smoker develops emphysema — the painter Pablo Picasso, who started smoking as a teenager but remained active and productive beyond his ninetieth year, comes to mind — and that genetic susceptibility factors underlie emphysema development. One alternative concept of emphysema pathogenesis is that the disease is a manifestation of premature aging of the lung; gene polymorphisms are being investigated, and researchers are searching for candidate genes that encode proteins that are components of inflammatory pathways, antioxidants, and proteolysis inhibitors. Many aspects of the pathobiology of human emphysema remain unclear. For example, it has been recognized for many years that human emphysema can affect the entire lung or have a predilection for the upper lobes and subpleural areas. The reasons for these regional differences in emphysema distribution are not understood. Evidence of both emphysema and pulmonary fibrosis in the same patient has been reported, implicating some common pathways leading to the different outcomes. It remains likewise unresolved why emphysematous lung destruction is relentlessly progressive in some patients even many years after smoking cessation.” (7)

  “Nowadays imaging is one of the key factors for the success of these therapies. Especially quantitative computed tomography (CT) with its increasing possibilities has become a viable tool, providing detailed information about distribution and heterogeneity of emphysema. Other imaging techniques like dual-energy CT (DECT) and functional magnetic resonance (MR) have shown to add functional information. These structural and functional information support thoracic surgeons and interventional pulmonologists in selecting patients and optimizing LVR procedures but also enables the development of new endobronchial therapies. Imaging will further improve the individual outcome by supporting the choice of optimal therapy.” (8)

 

References

(1, 5) Body height as risk factor for emphysema in COPD. Miniati, M., Bottai, M., Pavlickova, I. & Monti, S. Scientific Reports. 2016. https://www.nature.com/articles/srep36896

(2) Impact of pulmonary emphysema on exercise capacity and its physiological determinants in chronic obstructive pulmonary disease. Smith, B. M., Jensen, D., Brosseau, M., Benedetti, A., Coxson, H. C & Bourbeau, J. Scientific Reports. 2018. https://www.nature.com/articles/s41598-018-34014-5

(3) The Diagnosis of Mild Emphysema: Correlation of Computed Tomography and Pathology Scores. Kuwano, K., Matsuba, K., Ikeda, T., Murakami, J., Araki, A., Nishitani, H., Ishida, T., Yasumoto, K. & Shigematsu, N. American Review of Respiratory Disease. 1990. https://sci-hub.tw/https://www.atsjournals.org/doi/abs/10.1164/ajrccm/141.1.169?journalCode=arrd

(4) Emphysema. Kountz, W. B. & Alexander, H. L. 13 (3) 262. 1934. https://sci-hub.tw/10.1097/00005792-193409000-00001

(6) Sex differences in severe pulmonary emphysema. Martinez, F.J., Curtis, J. L., Sciurba, F., Mumford, J., Giardino, N. D., Weinmann, G., Kazerooni, E., Murray, S., Criner, G. J., Sin, D. D., Hogg , J., Ries, A. L., Han, M., Fishman, A. P., Make, B., Hoffman, E. A., Mohsenifar, Z. & Wise, R. American Journal of Respiratory and Critical Care Medicine. 2007. https://www.ncbi.nlm.nih.gov/pubmed/17431226

(7) Molecular pathogenesis of emphysema. Taraseviciene-Stewart, L. & Voelkel, N. B. The Journal of Critical Investigation. 2008. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2214683/

(8) Emphysema and lung volume reduction: the role of radiology. Martini, K. & Frauenfelder, T. Journal of Thoracic Diseases. 2018. http://jtd.amegroups.com/article/view/21531/17900

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