COPD

Question 1

With reference to the ‘Activity restriction in COPD’ paper, what mechanisms contribute to the increase in dyspnoea associated with COPD?

Answer 1

o Exercise and activity limitation are already apparent in patients at the mild stage of COPD (Global initiative for chronic Obstructive Lung Disease [GOLD] 1), exercise tolerance becoming increasingly compromised with disease progression.
o Exertional dyspnea and leg discomfort are common exercise-limiting symptoms in patients with COPD, including symptomatic patients with mild airflow obstruction.
o Both symptoms result from a complex interaction of factors, such as baseline respiratory mechanical dysfunction, individual susceptibility to leg muscle fatigue, type of exercise, and bronchodilation status, the consequences of which vary from patient to patient.
o As dyspnea and leg fatigue worsen, the patient leads a more sedentary lifestyle in order to avoid these symptoms, resulting in skeletal muscle deconditioning, exercise intolerance, and poor quality of life.

Question 2

In the lecture we discussed how changes in respiratory mechanics and skeletal muscle dysfunction limit exercise in COPD patients. With reference to the ‘Activity restriction in COPD’ paper, explain how changes in cardio-circulatory function may also limit exercise in COPD patients.

Answer 2

o In a large Danish population study, the presence of dyspnea and mild airway obstruction was shown to be an independent predictor of cardiovascular mortality
o Preclinical, mild airflow obstruction is associated with smaller left ventricular end diastolic volumes and decrements in stroke volume and cardiac output.
o Minor, increased emphysema is also associated with impaired left ventricular diastolic function and reduced cardiac output.
o Emphysematous destruction of lung parenchyma and pulmonary capillary beds, endothelial dysfunction, reduced pulmonary blood flow, and increased pulmonary vascular resistance have been suggested as possible underlying mechanisms responsible for these abnormalities

Question 3

With reference to the ‘Pulmonary rehabilitation in COPD’ paper, explain how deconditioning occurs in COPD patients and why such deconditioning may be central to increased disease severity.

Answer 3

o Physical training is important, even in healthy individuals, because muscle deconditioning occurs naturally as a consequence of inactivity—muscle mass, and the expression of genes associated with muscle growth, are both rapidly (within 2 weeks) reduced with muscle immobilisation
o Physical training is essential in order to address the disability (reductions in functional performance and quality of life) that can arise from muscle deconditioning and peripheral muscle dysfunction—caused by physical inactivity (due to chronic breathlessness and fatigue) and the systemic effects of chronic respiratory disease

Question 4

A key aspect to any pulmonary rehabilitation programme is the inclusion of an exercise component. A key consideration is the intensity at which such exercise should be performed. Based on the ‘Effectiveness of exercise training in COPD: role of muscle fatigue’ paper, what may be a novel way to prescribe exercise intensity during a pulmonary rehabilitation programme for COPD patients?

Answer 4

o The standard exercise modality was endurance training, but interval training (2 min episodes of exercise alternated with 1-min resting periods) was used if necessary to provide the desired training intensity.
o The training intensity was gradually increased over time, using a Borg scale rating of four to six on perceived exertion or dyspnoea as an indicator of adequate training intensity
o Interestingly, a high relative training intensity is no guarantee to provide a significant stimulus to the muscle.

Question 5

Is the acute response to smoking different between those with and without COPD?

Answer 5

o Smooth muscle cells from airway in those with and without COPD exposed to cigarette smoke extract
o Measured the production of key, pro-inflammatory cytokines

Question 6

What is COPD?

Answer 6

o A condition that makes it harder to breathe due to damage to airways and destruction of lung tissue (parenchyma)
o The collective (and preferred) term for patients with airflow obstruction and inflammation in the lungs, who were previously diagnosed with chronic bronchitis or emphysema
o A preventable condition, which is poorly reversible, and progressive in nature

Question 7

How is COPD diagnosed?

Answer 7

• There is no single diagnostic test for COPD
• A clinical judgement, based on history, examination and
confirmation of airflow obstruction using spirometry
-FEV1 lower than 80% predicted and is not fully reversible with bronchodilator
-Reduced FEV1/FVC (<70%, or <5th percentile)
-FEV1/FEV6
(percentile values)

Question 8

What risk factors does COPD have?

Answer 8

o	Genetics
o	Smoking
	Tobacco
	Cannabis
o	Pollution
	Occupational
	Indoor
	Environment
o	Sex
o	Age