Pathophysiology of Pneumonia
Pneumonia is the inflammation of the alveoli, which are sacs of the lungs that are microscopically filled with air that absorbs oxygen from our atmosphere, or the bronchioles (branch-like structures) of the lungs, caused by an acute infection. It is also sometimes referred to as pneumonitis or bronchopneumonia. Tortora & Grabowski explained that “when certain microbes enter the lungs of susceptible individuals, they release damaging toxins stimulating inflammation and immune responses that have damaging side effects.
The toxins and immune response damage alveoli and bronchial mucous membranes; inflammation and edema cause the alveoli to fill with debris and exudates (fluid) interfering with ventilation and gas exchange” (2004, page 845). Pneumonia is a common illness that affects all age groups and is known to be the most common cause of death from an infectious disease particularly among the elderly and people with debilitating diseases. Aetiology Pneumonia can result from a variety of causes, including infection with bacteria, viruses, fungi or parasites.
Pneumonia may also occur from chemical or physical injury to the lungs or indirectly due to another medical illness, such as lung cancer or alcohol abuse (Medic8 Family Heath Guide). In addition to this, pneumonia can also be acquired from gastric secretions that are aspirated into the lungs. Porth classified pneumonia as typical (i. e. , bacterial) or atypical (i. e. , viral or mycoplasmal) pneumonias. Typical pneumonia results from infection by bacteria that multiply extracellularly (outside the cell) in the alveoli and cause inflammation and exudation of fluid (filling up of fluid) into the air-filled spaces of the alveoli.
Atypical pneumonias produce patchy inflammatory changes that are confined to the alveolar septum and the interstitium of the lung (2004, page 360). The most common causes of pneumonia are viruses and bacteria. Community-acquired pneumonia or CAP is an infectious pneumonia in a person who has not been hospitalised recently. This is the most common cause of community-acquired pneumonia are “Streptococcus pneumoniae, viruses, the atypical bacteria, and Haemophilus influenzae. Overall, Streptococcus pneumonia is the most common cause of community-acquired pneumonia worldwide” (Schmitt).
Hospital-acquired pneumonia or nosocomial pneumonia on the other hand, is pneumonia that was acquired during hospitalization for a different illness. This type of pneumonia tends to be more serious among the two because the organisms found in a hospital often become resistant to many antibiotics. Also, hospitalized patients are bound to be weakened by other illnesses and are less able to fight off the infection. “Hospitalized patients may have many risk factors for pneumonia, including mechanical ventilation, prolonged malnutrition, underlying heart and lung diseases, decreased amounts of stomach acid and immune disturbances.
Additionally, the microorganisms a person is exposed to in a hospital are often different from those at home. Hospital-acquired microorganisms may include resistant bacteria such as MRSA, Pseudomonas, Enterobacter, and Serratia. Because individuals with hospital-acquired pneumonia usually have underlying illnesses and are exposed to more dangerous bacteria, it tends to be more deadly than community-acquired pneumonia. Ventilator-associated pneumonia (VAP) is a subset of hospital-acquired pneumonia. VAP is pneumonia which occurs after at least 48 hours of intubation and mechanical ventilation” (Schmitt).
Clinical Manifestations There are several signs and symptoms that could lead to the diagnosis of pneumonia. One clear manifestation that a person has infectious pneumonia is when he often has a productive cough that produces either greenish or yellowish sputum or phlegm and on some occasions coughing up blood, has a high fever that is accompanied by chills that make the person either shiver or shake. Another common symptom is shortness of breath coupled with pleuritic chest pains (stabbing or sharp pain) experienced either during deep breaths or experiences and increase in pain while coughing.
People with pneumonia tend to have headaches or experience having cold, sweaty and clammy skin. Some other possible symptoms are sudden loss of appetite, fatigue or gets tired easily, nausea and vomiting, cyanosis or blueness of the skin, joint and muscle pains. “Pneumonia caused by Legionella may cause abdominal pain and diarrhea, while pneumonia caused by tuberculosis or pneumocystis may cause only weight loss and night sweats. In elderly people manifestations of pneumonia may not be typical.
They may develop a new or worsening confusion or may experience unsteadiness, leading to falls. Infants with pneumonia may have many of the symptoms above, but in many cases they are simply sleepy or have a decreased appetite” (Schools-Wikipedia. org, 2008). Additional symptoms that may be associated with this disease are shortness of breath, nasal flaring (enlargement of the nostrils during breathing), tachypnea (fast or rapid breathing), apnoea (suspension or cessation of breathing during sleep), anxiety, stress tension and abdominal pains (Sonic.
net). According to Schmitt, symptoms of pneumonia need immediate medical evaluation. Physical examination by a health care provider may reveal fever or sometimes low body temperature, an increased respiratory rate, low blood pressure, a high heart rate, or low oxygen saturation, which is the amount of oxygen in the blood as indicated by either pulse oximetry or blood gas analysis. People who are struggling to breathe, who are confused, or who have cyanosis (blue-tinged skin) require immediate attention.
Schmitt added that physical examination of the lungs may be normal, but often shows decreased expansion of the chest on the affected side, bronchial breathing on auscultation with a stethoscope (harsher sounds from the larger airways transmitted through the inflamed and consolidated lung), and rales (or crackles) heard over the affected area during inspiration. Percussion may be dulled over the affected lung, but increased rather than decreased vocal resonance (which distinguishes it from a pleural effusion). While these signs are relevant, they are insufficient to diagnose or rule out pneumonia.
“To diagnose pneumonia, health care providers rely on a patient’s symptoms and findings from physical examination. Information from a chest X-ray, blood tests, and sputum cultures may also be helpful. The chest X-ray is typically used for diagnosis in hospitals and some clinics with X-ray facilities. However, in a community setting (general practice), pneumonia is usually diagnosed based on symptoms and physical examination alone. Diagnosing pneumonia can be difficult in some people, especially those who have other illnesses.
Occasionally a chest CT scan or other tests may be needed to distinguish pneumonia from other illnesses” (Medic8 Family Heath Guide). Pathophysiology As a springboard for this concept analysis, an internet search was done on the term Pathophysiology. Dictionary. com defines Pathophysiology as the functional changes associated with or resulting from disease or injury. Wikipedia, a popular online source of information defines Pathophysiology as “the study of the changes of normal mechanical, physical and biochemical functions either caused by a disease or resulting from an abnormal syndrome” (Wikipedia, 2009).
Discussing a little bit about anatomy and physiology, the lungs are the largest organ in the respiratory system. They play a vital role in providing the systems of the body with oxygen and is also responsible for aiding in releasing carbon dioxide by expanding when oxygen is taken in and contracting when carbon dioxide is released or disposed. The air that we breathe in is filled with oxygen and passes through the trachea prior to branching off into one of the two bronchi. Each bronchus leads to one part of the lungs.
Within the lungs, the bronchi branches out into small pathways called bronchioles that go through the lung tissue and ending up in the small air sacs or alveoli. The alveoli are surrounded by capillaries that are responsible for providing oxygen to the blood. The oxygenated blood is then pumped by the heart and circulates to the systems of the body. Each lung is surrounded by a two-layered membrane called the pleura which has a small amount of fluid between layers. This fluid allows smooth passage of air and less friction on the membranes during the breathing process.
Since the alveoli is the one that gets inflamed during the onset of pneumonia, the net effects of pneumonia are: decreased oxygenation of the blood or tissue hypoxia, lack of oxygen in the organs of the body or generalized anoxia and because of air hunger, people with pneumonia breathes very fast or hyperventilates and results into an increase in the rate of breathing or tachypnea. This increase in the rate of breathing leads to blowing off more carbon dioxide than usual and because of this; blood ph is also increased.
The arterial blood gas (ABG test measures the acidity (pH) and the levels of oxygen and carbon dioxide in the blood from an artery. This test is used to check how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood pH. The pH measures hydrogen ions (H+) in blood. The pH of blood is usually between 7. 35 and 7. 45. A pH of less than 7. 0 is called acid and a pH greater than 7. 0 is called basic (alkaline). So blood is slightly basic. Bicarbonate (HC03) is a chemical (buffer) that keeps the pH of blood from becoming too acidic or too basic. (WebMD, 2008)
Water (H2O) + Carbon dioxide (CO2) leads to carbonic acid (H2 CO2) and eventually dissociates to HCO3 + H+ (H+ is an acid). When the body lacks acid, it goes to an alkaline side and eventually leads to difficulty of breathing or dyspnea in patients who are diagnosed with pneumonia. PHC Management Pneumonia patients usually experience difficulty of breathing or tachypnea because of the fluid in the lungs and the inflammation of the alveoli. The proper management for this type of illness is to always take note of the ABC mnemonic of CPR which stands for Airway, Breathing and Circulation.
Make sure that the posture is enough for air to pass through easily. Once this is achieved, make sure to keep the airway open. In the event that the patient is still having difficulty breathing, rush the patient to the hospital for oxygenation and proper medical attention. In severe cases, IV access is important to administer medications and check ABG levels and hook the patient to a cardiac monitor. Emergency Management The usual emergency complaint for pneumonia patients is difficulty breathing. The emergency management for this situation is to provide oxygenation.
In instances wherein there is a threat for respiratory and circulatory failure, non –invasive breathing assistance such as a “bilevel positive airway pressure machine” could be helpful (Wikipediaondvd. com). Placement of an endotracheal or breathing tube and in the hospital’s intensive care unit may be really necessary and a ventilator may also used to aid in the patients’ breathing. Pneumonia can also cause respiratory failure by triggering acute respiratory distress syndrome (ARDS), which results from a combination of infection and inflammatory response.
The lungs quickly fill with fluid and become very stiff. This stiffness, combined with severe difficulties extracting oxygen due to the alveolar fluid, create a need for mechanical ventilation. (Wikipediaondvd. com) Occasionally, microorganisms infecting the lung will cause fluid (a pleural effusion) to build up in the space that surrounds the lung (the pleural cavity). If the microorganisms themselves are present in the pleural cavity, the fluid collection is called emphysema.
When pleural fluid is present in a person with pneumonia, the fluid can often be collected with a needle (thoracentesis) and examined. Depending on the results of this examination, complete drainage of the fluid may be necessary, often requiring a chest tube. In severe cases of emphysema, surgery may be needed. If the fluid is not drained, the infection may persist, because antibiotics do not penetrate well into the pleural cavity (Wikipediaondvd. com). References (n. d. ). Retrieved May 9, 2009, from Medic8 Family Heath Guide: http://www. medic8.
com/healthguide/articles/pneumonia. html (n. d. ). Retrieved May 8, 2009, from Sonic. net: http://www. sonic. net/~danslist/pathos/pneumoniapatho. htm Dictionary. com. (n. d. ). Retrieved May 9, 2009, from http://dictionary. reference. com/browse/pathophysiology Porth, C. M. (2004). Essentials of Pathophysiology. Philadelphia: Lippincott Williams & Wilkins. Schmitt, S. (n. d. ). Cleveland Clinic. Retrieved May 8, 2009, from Community-Acquired Pneumonia: http://www. clevelandclinicmeded. com/medicalpubs/diseasemanagement/ infectious-disease/community-acquired-pneumonia/
Schools-Wikipedia. org. (2008, September). Retrieved May 10, 2009, from http://schools- wikipedia. org/wp/p/Pneumonia. htm Tortora, G. J. , & Grabowski, S. R. (2004). Principles of Anatomy and Physiology (10th ed. ). New York: John Wiley & Sons, Inc. WebMD. (2008, June 17). Webmd. com. Retrieved May 8, 2009, from Arterial Blood Gas (ABG): http://www. webmd. com/a-to-z-guides/arterial-blood-gases Wikipedia. (2009, April 20). Article on Pathophysiology. Retrieved May 9, 2009, from Wikipedia. com: http://en. wikipedia. org/wiki/Pathophysiology
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