Age -Related Pulmonary changes

1. Age -Related Pulmonary changes By Dr. Michael Banoub

2. Thoracic Pump Alterations The mobility reduction in the thoracic rib cage is suggested to result from two primary tissue alterations. The first is an increase in the cross-linking of collagen fibers both in the ribs and in the connecting sternal cartilage. The second is primarily a vertebral column change whereby the intervertebral annulus fibrosis becomes stiffer due to water loss, causing a subsequent reduction in the cushioning distance between the intervertebral disks. That result is a shorter, more rigid thorax that is resistant to deformation and therefore requires greater ventilatory muscle force to achieve a change in the intrathoracic pressure

4. Tidal volume – volume inhaled and exhaled during normal breathing Inspiratory reserve volume – volume which can be inhaled additionally after normal inspiration Expiratory reserve volume – volume which can be exhaled additionally after normal expiration Residual volume – volume remaining in the lungs after maximal expiration

5. 5- Vital capacity – volume which can be exhaled after maximal inspiration (sum of 1, 2 and 3) 6-Inspiratory capacity – volume that can be inhaled additionally after normal expiration (sum of 1 and 2) 7-Functional residual capacity – volume remaining in the lung after the end of a normal expiration (sum of 3 and 4) 8-Total capacity – volume filling the lung after maximal inspiration (sum of 1, 2, 3 and 4)

8. Residual volume and FRC are however increased with the loss of elastic recoil and increased stiffness of the chest wall. • Distal airway closure during expiration, or closing volume (CV), increases with loss of the lung's supporting network, resulting in collapse of distal lung segments and gas trapping in the lungs. • There is a proportional decline in VC as the RV increases

9. Ventilatory Work of Breathing • Essentially, the musculoskeletal ventilatory pump has to carry out its function at a progressively increasing mechanical disadvantage over the course of time • the increase in RV and FRV. means that the chest wall is actually held in a position of partial inspiration. and primarily flattens the diaphragm. The position change reduces the muscle's potential contractile force.

10. Gas Exchange Alteration with Aging • As the supporting framework for the alveolar structures breaks down, the resultant lung collapse produces both uneven ventilation and uneven circulation or greater potential for V/Q. mismatch.

11. The progressive airway closure and alveolar breakdown that occur at the lung bases with aging indicate that the inspired gas, traveling in the path of least resistance, to the lung apices, thereby creating more V/Q mismatching as blood flow continues to be greater at the bases .