Saturday, February, 11, 2012

Aging changes in the lungs

Table of Contents

AGING CHANGES

People normally make new alveoli until about age 20. After that, the lungs begin to lose some of their tissue. The number of alveoli decreases, and there is a corresponding decrease in lung capillaries. The lungs also become less elastic (able to expand and contract) due to various factors including the loss of a tissue protein called elastin.

Changes in the bones and muscles increase the front-to-back size of the chest. Loss of bone mass in the ribs and spine bones (vertabrae), and mineral deposits in the rib cartilage, change the curve of the spine. There may be front-to-back curvature (kyphosis or lordosis) or side-to-side curvature (scoliosis).

The maximal force you can generate when breathing in (inspiration) or when breathing out (expiration) decreases with age, as the diaphragm and muscles between the ribs (intercostals) become weaker. The chest is less able to stretch to breathe, and the pattern of breathing may change slightly to compensate for this decreased ability to expand the chest.

EFFECT OF CHANGES

Maximum lung function decreases with age. The amount of oxygen diffusing from the air sacs into the blood decreases. The rate of air flow through the airways slowly declines after age 30. And the maximal force you can generate on inspiration and expiration decreases. However, even elderly people should have adequate lung function to carry out daily activities, because we have "extra" lung function in our youth. This is why normal people can tolerate surgical removal of an entire lung and still breathe reasonably well.

An important change for many older people is that the airways close more readily. The airways tend to collapse when an older person breathes shallowly or when they're in bed for a prolonged time. Breathing shallowly because of pain, illness, or surgery causes an increased risk for pneumonia or other lung problems. As a result, it is important for older people to be out of bed as much as possible, even when ill or after surgery. When this is not possible, it is helpful to do "incentive spirometry." This involves blowing into a small device to help keep the airways open and clear of mucus.

Normally, breathing is controlled by the brain. It receives information from various parts of the body telling it how much oxygen and carbon dioxide are in the blood. Low oxygen levels or high carbon dioxide levels trigger an increased rate and depth of breathing. It is normal for even healthy older people to have a reduced response to both decreased oxygen and increased carbon dioxide levels.

The voice box (larynx) also changes with aging. This causes the pitch, loudness, and quality of the voice to change. The voice may become quieter and slightly hoarse. The pitch may be decreased (becoming lower) in women and increased (becoming higher) in men. The voice may sound "weaker," but most people remain quite capable of effective communication.

COMMON PROBLEMS

Elderly people are at increased risk for lung infections. The body has many ways to protect against lung infections. With aging, these defenses may weaken.

Review Date: 11/29/2010
Reviewed By: Andrew Schriber, MD, FCCP, Specialist in Pulmonary, Critical Care, and Sleep Medicine, Virtua Memorial Hospital, Mount Holly, New Jersey. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)