Pneumonia Case Study
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Case Study
Pneumonia
Pneumonia is defined as an illness of the lungs and respiratory system in which the
Alveoli (microscopic air-filled sacs of the lung responsible for absorbing oxygen from the atmosphere) become inflamed and flooded with fluid (Wikipedia, 2006). There are over 100 strains of microorganisms that can cause infectious pneumonia and only a few of them are responsible for most cases. The most common causes of infectious pneumonia are bacteria and viruses. Fungi and parasites can each also cause of infectious pneumonia. Inhalation of a chemical or an injury to the lung can also cause a pneumonia to develop. Other medical conditions such as lung cancer, AIDS, emphysema, cystic fibrosis, tobacco smoking, and alcohol abuse can place patients at an increased risk of developing pneumonia. Aspiration of gastric secretions or gastric contents into the lungs is a cause of pneumonia. This is the rational behind checking residuals for patients receiving peg tube feedings and someone having nothing to eat or drink a certain amount of time before moderate sedation for procedures, or general anesthesia. Pneumonia is the sixth leading cause of death in the United States and the most common cause of death from infections disease (Porth, 2005). An estimated two to three million cases of pneumonia occur in the United States each year (Porth, 2005). According to Porth (2005), although antibiotics have significantly reduced the mortality rate from pneumonias, these diseases remain an important immediate cause of death of the elderly and persons with debilitating diseases. The severity and mortality of pneumonia can be affected by the general health, age, and ability / desire to receive treatment. There are more cases of pneumonia during the winter months because people are in close proximity to each other while being indoors. Pneumonia occurs more commonly in males than females, and more often in blacks than Caucasians (Wikipedia, 2006).
Bacterial pneumonias are the most common and the most serious in adults. The most common type is Streptococcus pneumoniae (pneumococcus). Respiratory viruses are the most common cause of pneumonia with the highest rate among two to three year olds. For school age children, the most common cause of pneumonia is Mycoplasma pneumoniae.
The lungs are soft, spongy, cone-shaped organs located side by side in the chest cavity. The right side is divided into three lobes (upper, middle, and lower) and the left side is divided into two lobes (upper and lower). The lungs are multifunctional organs. Lungs serve in both a ventilation and perfusion capacity for the body. They serve as a gas exchanger by taking in oxygen and give off carbon dioxide into the air during inspiration and expiration. The gas exchange takes place in the lobules which are the smallest functional units of the lung. Each lobule is supplied by a terminal bronchiole, an arteriole, the pulmonary capillaries, and a venule. Gas exchange takes place in the terminal respiratory bronchioles and the alveolar ducts and sacs. Blood enters the lobules via the pulmonary artery (the only artery that carries unoxegenated blood in the body) from the right ventricle of the heart. There are approximately three hundred million alveoli sacs in the lung. Alveolar cells are divided into two types: Type I and Type II cells. Type I cells, where the gas exchange takes place are flat squammous epithelial cells. Type II cells produce surfactant, a lipoprotein substance that decreases the surface tension of the alveoli. This action allows for greater ease of lung inflation and helps to prevent the collapse of the smaller airways. The alveoli contain macrophages which are responsible for removing offending substances from the alveolar epithelium. Oxygenated blood leaves the lungs via the pulmonary vein and enters the left atrium of the heart to begin the path of oxygenated blood through the body. The lungs also inactivate vasoactive substances such as bradykinin and convert angiotensin I to Angitensin II. They also serve as a reservoir for blood.
The above diagram illustrates the lungs, main bronchus, and diphram.
Information on the status of breathing is provided by receptors in the lungs and the chest wall. These receptors sense airway resistance and lung expansion. There are three types of receptors: stretch, irritant, and juxtacapillary receptors.
Stretch receptors are located in the smooth muscle layers of the conducting airways. These receptors respond to changes in pressure in the walls of the airways. The Hering-Breuer reflex is when the lungs are inflated and the stretch receptors inhibit inspiration and promote expiration. Stretch receptors accommodate changes in lung compliance and airway resistance by adjusting the respiratory rate. These receptors are important in establishing the pattern of breathing help to decrease the work of breathing .
Irritant receptors are located between the airway epithelial cells. Stimulation occurs by the introduction of noxious gases, cigarette smoke, inhaled dust, and cold air. This leads to airway constriction and a pattern of rapid, shallow breathing. This pattern of breathing is thought to protect the respiratory tissues from possibly damaging effects of toxic inhalants.
Juxtacapillary receptors are located in the capillary wall. The theory is that these cells sense lung congestion and are thought to be responsible for inducing rapid, shallow breathing. This is seen in pulmonary edema, pulmonary embolism, and pneumonia.
The normal tidal volume (the volume of air that moves in and out of the lungs in a single breath) (TV) is 500 milliliters (mL). The tidal volume is a necessary component for mechanical ventilation settings for someone in respiratory failure. Inspiratory Reserve Volume (IRV) is the maximum amount of air that can be inspired in excess of the normal TV. Expiratory Reserve Volume (ERV) is the maximum amount of air exhaled in excess of the normal TV. Residual Volume (RV) is the amount of air left in the lungs after forced expiration. The average RV is twelve hundred mL. These volumes may vary in patients with diseases such as pneumonia, emphysema. abestosis, and lung cancer.
The previous diagram illustrates the path oxygen takes as it enters the body through the nasal cavity to the alveoli.
Symptoms present in a