the HAE series: the Pulmonary System part II
Normal Changes with Aging
As with all areas of the body, with advancing age, the lungs can be come less efficient. The diaphragm muscle responsible for the inhalation and exhalation can become weaker, decreasing the amount of air you can take in and out each breath. With thinning ribs and arthritic changes, the rib cage can become less flexible and cause some restriction on your inhalation. Combined, these two changes can increase the work associated with breathing. Other accessory muscles involved with respiration can also become weaker, interfering with your ability to cough and in turn, clear your airway. With age also comes a weakening response of the immune system; the white blood cells that usually provide some defense to invading pathogens within the lungs become less effective putting your at increase risk of infections like community-acquired pneumonia Lastly, within the lungs, the alveoli lose their shape and this in turn makes gas exchange more difficult. Aside from the changes occurring naturally with age, I’ll review some pathology common in older adults. (But don’t fret, next week I’ll share how we can slow or reverse these changes through our actions!)
What Can Go Wrong
Pneumonia: As mentioned above, weakened immune systems can leave the pulmonary system at risk of infection. Infection within the lungs is called pneumonia. The result of inflammation at the alveoli, the gas exchange is impaired and the body can end up in a state of hypoxia, or decreased oxygenation. Other symptoms are typically cough, fever, back pain (typically near the site of the infected lung) and audible ‘crackles’ that can be heard through auscultation. More progressive cases can cause confusion, altered sleep and wake cycles and failure to thrive. Risk factors for pneumonia include immune compromise and immobility. The ability to move air throughout the lungs can help clear out pathogens and as such, it is of critical importance to use strategies like incentive spirometry or deep breathing during periods of immobility after a surgery, during a hospital stay or during a state of illness. Pneumonia is typically treated with an antibiotic if is caused by bacteria, however, some strains of pneumonia can be prevented prophylactically with the pneumococcal vaccine.
COPD: Chronic Obstructive Pulmonary Disease, or COPD, causes difficulty breathing by way of ‘air trapping.’ In the case of emphysema, destruction of the alveoli due to exposure to irritants like cigarette smoke, causes impaired air exchange and the trapping of carbon dioxide. With chronic bronchitis, inflammation within the bronchial tubes make it harder to inhale and exhale and with chronic asthma, the obstruction is due to inflammation within the airways causing bronchoconstriction, or narrowing of the bronchioles. These disease states leave the lungs less elastic and airways more prone to collapse and this combined, obstructs expiration. People experiencing COPD will have symptoms associated with hypoxia, or decreased oxygen, like coughing, difficulty breathing, confusion and fatigue. Treatment mainstays include keeping the airways open longer during the exhale phase with strategies like pursed lip breathing or spirometry, use of bronchodilators (inhalers) and supportive oxygen in later stages.
Restrictive Lung Disease: As introduced above, disease and disorders that affect the muscles and bone structure can cause an external restriction in the ability for the lungs to expand. Restrictive disease can be classified as either intrinsic or extrinsic. Intrinsic causes include general fibrosis of the lung parenchyma and extrinsic causes involve the lung pleura, chest wall, respiratory muscles or neuromuscular disorders. Neuromuscular conditions like Parkinson’s Disease and musculoskeletal changes like rib fractures and thoracic kyphosis and scoliosis can cause structural changes to the rib cage and lost flexibility. Increased body weight and obesity can block the diaphragm from descending fully and can make both inhale and exhalation more difficult and cardiovascular causes, like pulmonary edema from heart failure can restrict lung expansion from the inside. Presentation involves dyspnea compensated for by rapid shallow breathing and patients will demonstrate a decreased total lung capacity, modestly preserved FEV1, increase airway resistance and a decreased FVC that results in a FEV1/FEV ratio greater than 80%, as well as a reduction in functional residual capacity (FRC), or the amount of air in the lungs that remains when respiratory muscles are fully relaxed.
Treatment for these conditions must address the etiology; stretching, range of motion and postural reeducation may help in cases that have not yet progressed to severe and treating the CHF through pharmacologic management and lifestyle modification will address the cause in the case of pulmonary hypertension.
Pulmonary Hypertension: PH is a condition in which mean pulmonary arterial pressure is greater than 25 mmHG at rest. Pulmonary Arterial Hypertension (PAH) is a specific clinical condition of PH in absence of other causes of precapillary HTN. It is quite rare (1, 1000,000-1,000,000). PH is less uncommon, 1% of the population, and is often associated with other hypoxic cardiopulmonary disease like COPD and diffuse parehnchymal lung disease. In setting of hypoxia, pulmonary arterial smooth muscle contracts to cause vasoconstriction to promote ventilation matching, but in chronic hypoxic lung disease, the increased pulmonary vascular resistance resulting from hypoxic pulmonary vasoconstriction causes the development of PH. Symptoms usually include dyspnea, fatigue, general signs of cardiovascular dysfunction (syncope, angina, heart murmurs) and signs of pathologically elevated systemic blood pressure (ascites, edema, jugular distension). Exercise capacity is limited, and individuals with PH experience increased dyspnea due to inspiratory and expiratory muscle weakness.
