COPD The third leading cause of death Progressive course No cure yet

Management Of COPD

Surgical Lung Volume Reduction

In LVRS, 20 percent to 35 percent of the most damaged regions of each lung is removed, helping the remaining lung to function better, thereby easing symptoms associated with advanced emphysema

The mechanisms by which LVRS might provide benefit

1. reduces the size mismatching between the hyperinflated lungs and the chest cavity, increasing elastic recoil and improving expiratory airflow

2. Improvement in the mechanical function of the diaphragm and intercostalmuscles by decreasing the functional residual capacity

3. Improved left ventricular filling

4. Reduction in lung volumes during exercise (ie, reduced dynamic hyperinflation), which is associated with reduced exertional dyspnea

Leading to :

• Improved forced expiratory volume in 1 second

• Improved gas transfer

• Improved exercise tolerance and quality of life

LVRS is contraindicated in such patients

the 30-day mortality 2years, total mortality

16% 0%

2.2%

0.2%

Improvement in exercise capacity at 24 months compared with the post-rehabilitation baseline

indications :Age < 75 years Severe dyspnea despite optimal medical therapy and maximal pulmonary rehabilitation > 6 months of smoking cessationFEV1 < 45 % predicted and > 20%(DLCO) that is NOT less than 20 % predicted hyperinflation and heterogeneously distributed emphysema( predominantly upper lung zone emphysema are more likely to benefit ).Post-rehabilitation, a six-minute walk distance greater than 140 meters

Bronchoscopic Lung Volume Reduction

The beneficial effects following valve insertion have varied a lot but include:

• Improved forced expiratory volume in 1 second

• Improved gas transfer

• Improved exercise tolerance and quality of life

• Reduction in dynamic hyperinflation.

Why should only a proportion of patients

develop atelectasis after valve insertion?

One possibility is simply leaking valves

The other possibility is that variability in the amount of

collateral ventilation

IN OTHER WORDS , CV PREVENTS ATALECTASIS ANDIT’S THE MAIN CAUSE OF BLVR FAILURE

Definition :“the ventilation of alveolar structures through passages or channels that bypass the normal airways”

And these are :•Inter-bronchiolar

•Inter-alveolar

•Bronchiolo-alveolar.

•Interlobar “ throughfissues “

What’s the significance of CV ?

The resistance to collateral flow in human lungs has been measured and found to be 50 times greater than the resistance to flow through the normal airways.It therefore seems that collateral ventilation has NO SIGNIFICANCE in subjects with NORMAL AIRWAYS.

However, the resistance to collateral flow is markedly reduced certain

conditions including emphysema due to : 1. Destruction of terminal bronchioles opening of CV2. Significant expiratory airflow obstruction by “collapse + mucus plugging”

And This reduces Atalectasis andimprove Gas Exhange …………… how ??

In an rea of complete obstruction with collateral ventilation collateral ventilation can prevent atelectasis in the setting of airflow obstruction and they found thagases t the PaO2 was higher and the PaCO2 lower than concurrent arterial blood in the absence of CV

In other words, areas of lung that are only collaterally ventilated can still carry out useful gas exchange—that is, collateral channels allow obstructed areas to maintain a useful degree of function

In an area of lung that is completely obstructed, without collateral ventilation

alveolar gas tensions within the obstructed area rapidly equilibrate with mixed venous blood

no further gas exchange occurs alveolar gas is absorbed atelectasis develops

Influence of parenchymal diseases on collateral ventilation

EmphysemaThe increase of FRC due to the loss of elastic recoil can also increase the size of the collateral channels in emphysema

Fibrosis collateral resistance increases in fibrotic segments because lung volume decreases, andbecause the collateral pathways are involved directly in the fibrotic process

Atelectasisthe poor collateral ventilation of the human middle lobe explains why atelectasis of the middle lobe occurs after airways obstruction or infection

MEASURING COLLATERALVENTILATION

•Resistance can be measured directly via a wedged bronchoscope with selected bronchi occluded

collateral resistance may be inferred from the distribution of inhaled gas during a single breath :xenon and ventilation

scintigraphyhyperpolarized helium MRI