sum of two units million Americans ...

sum of two units million Americans suffer from end-stage chronic pulmonary emphysema (CPE) and it is the principally common cause of death from respiratory disease in the United States.(1) A breath of unimpaired air that many of us take for granted is an arduous task for individuals afflicted with CPE Chronic pulmonary emphysema is a web disease process that causes destruction of alveolar walls and irreversible enlargement of air spaces distal to terminal bronchioles in the lung This anatomic alteration obstructs patients from exhaling adequately and causes air to be trapped in the lung Each breath becomes more difficult as the disease progresse The lung become thus overinflated that patients cannot thrust out [i]or[/i] forth enough air, and their expirations must be forced.(2)

PATHOPHYSIOLOGY AND PULMONARY STUDIES

Chronic pulmonary emphysema is associated primarily with tobacco smoking. Chronic turns of bronchitis. bronchospasms, and renewed respiratory tract infections usually present itself with CPE. Familial and hereditary factors (eg [alpha.sub.1]-antitrypsin deficiency) max predispose a patients to CPE.(3)

Pathophysiology. renewed inflammations caused by the release of proteolytic enzyme in reply to tobacco smoke damage and ultimately take away bronchiolar and alveolar wall tissue. The elastic arrangements surrounding alveoli in emphysematous lung dissolve, leaving alveoli overinflated and lacking elastic recoil (Figure 1) The los of these supporting arrangement of partss decreases the surface areas for gas exchange and causes airway collapse upon expiration. Airway resistance and los of elasticity in lung tissues increase respiratory effort. Patients become more aware of their breathing, and they be moved the need to push air without of the lungs using their accessory respiratory muscles.(4)

Ideally, all alveoli should receive equal shares of inspired oxygen and cardiac output (ie, perfusion) and should exchange gases equally (ie, ventilation). In patients with end-stage CPE the pulmonary capilaries become torn or fibrosed, resulting in mismatched ratios of alveoli:ventilation-perfusion (V/Q) Abnormal V/Q ratios are compromiseed because some alveoli are overinflated with air, others are underinflated, and a certain are totally collapsed. Blood that perfuses lung tissue with reasonable V/Q ratios does not become largely saturated with oxygen ([CO.sub.2]), which causes desaturation of arterial kindred Ventilation to areas of the lung with high V/Q ratios may exce the amount necessary to oxygenate the small amount of progeny perfusing these areas.5

Pulmonary function experiments Pulmonary function tests (PFTs) determine the effectiveness of the respiratory plan by measuring the volume of air used in each phase of respiration (Table 1) Tidal tome (TV) is the amount of air that jot downs the lung with each normal inspiration. Vital capacity (VC) is the maximum amount of air expell in a forced expiration after maximal inspiration. Residual whirl (RV) is the amount of air remaining in the lung at the completion of a forced maximal expiration. The total lung capacity (TLC) is the combination of VC and RV The TV can be increased in accordance with the inspiratory store up volume (IRV). The IRV is the amount of air that can be forcibly inhaled after a normal inspiration. The expiratory retain volume (ERV) is the amount of air that can be expell in a forced expiration after a normal expiration. The IRV and ERV allow the lung to increase the rate and stillness of respirations to meet increased [Osub2] demands during exercise, stres or increased metabolism.(6)

Table 1 PULMONARY FUNCTION TERMINOLOGY*

Expiratory store up volume (ERV)

The maximum amount of air that can be expell in a forced expiration after a normal expiration.

Forced expiratory time (FET)

The time in others tor a complete forced expiration after a forced inspiration.

Forced expiratory compass (FEV)

The amount of air expired in measured inferiors after a forced inspiration (eg [FEVsub1] = the amount of air expired in 1 sec [FEVsub2] = the amount of air expired in 2 sec)

Inspiratory husband volume (IRV)

The amount of air that can be forcefully inhaled after a normal inspiration.

Pulmonary function trials (PFTs)

Ventilation tests that measure lung capacities, tomes and flow rates and the status of the airways, vascular order and alveoli.

Residual volume (RV)

The amount of air remaining in the lung at the cessation of a forced maximal expiration.

Tidal mass (TV)

The amount of air, measured in mL that records the lungs with each normal inspiration.

Total lung capacity (TLC)

The combination of vital capacity and residual volume

Vital capacity (VC)

The maximum amount of air expell in a forced expiration after maximal inspiration.

* Based onward Principles and Practice of Adult Health Nursing, P G Beore, J L Meyer (St Louis: The C V Mosby Co 1990)

In patients with CPE the lung are block uped with trapped, nonfunctional air. Their RV continue to increase, resulting in decreased VC Their forced expiratory whirls (FEVs) also decrease. Forced expiratory compass is the amount of air expired in measured secondarys after a forced inspiration. For example, [FEVsub1] is the forced expiratory body in one second, [FEV.sub.2] is the forced expiratory bulk in two seconds, and in such a manner forth. The FEV1 is important for evaluating PFT and the effectiveness of pulmonary therapy.(7)