pneumonia..

WHAT IS PNEUMONIA?

Pneumonia is an inflammation of the lung caused by infection with bacteria, viruses, and other organisms. Pneumonia is usually triggered when a patient's defense system is weakened, most often by a simple viral upper respiratory tract infection or a case of influenza. Such infections or other triggers do not cause pneumonia directly but they alter the mucous blanket, thus encouraging bacterial growth. Other factors can also make specific people susceptible to bacterial growth and pneumonia
PATHOPHYSIOLOGY

WHAT CAUSES PNEUMONIA?
Bacteria are the most common causes of pneumonia, but these infections can also be caused by other microbial organisms. It is often impossible to identify the specific culprit.Bacteria
Many bacteria are categorized by the staining procedure used to visualize bacteria under a microscope. The stains determine if they are gram-negative or gram-positive bacteria. This gives the physician an idea of the severity of the pneumonia and how to treat it.

Gram-Positive Bacteria. These bacteria appear blue on the stain. The following are common gram-positive bacteria:
• The most common cause of pneumonia is the gram-positive bacterium Streptococcus pneumoniae (also called S. pneumoniae or pneumococcal pneumonia). It was thought to cause 95% of community-acquired bacterial infection, but research now indicates it is far less, accounting for about half of all cases. (Some studies suggest it may account for even fewer, 10% to 30% of cases.)
• Staphylococcus aureus, the other major gram-positive bacterium responsible for pneumonia, accounts for about 10% of bacterial cases. It is one of the main causes of pneumonia that occurs in the hospital (nosocomial pneumonia). It is uncommon in healthy adults but can develop about five days after viral influenza, usually in susceptible individuals, such as people with weakened immune systems, very young children, hospitalized patients, and drug abusers who use needles.
• Streptococcus pyogenes or Group A Streptococcus.
Gram-Negative Bacteria. These bacteria stain pink. Gram-negative bacteria are common infectious agents in hospitalized or nursing home patients, children with cystic fibrosis, and people with chronic lung conditions.
• The most common gram-negative species causing pneumonia is Haemophilus influenzae (generally occurring in patients with chronic lung disease, older patients, and alcoholics).
• Klebsiella pneumoniae may be responsible for pneumonia in alcoholics and in other people who are physically debilitated.
• Pseudomonas aeruginosa is a major cause of pneumonia that occurs in the hospital (nosocomial pneumonia). It is common in pneumonia patients with chronic or severe lung disease.
• Moraxella catarrhalis is found in everyone's nasal and oral passages. Experts have identified these bacteria as a cause of certain pneumonias, particularly in people with lung problems, such as asthma or emphysema.
• Neisseria meningitidis is one of the most common causes of meningitis (central nervous system infection), but the organism has been reported in pneumonia, particularly in epidemics of military recruits.
Other gram-negative bacteria that cause pneumonia include E. coli (a cause in newborns), Proteus (found in several damaged lung tissue), and Enterobacter.

Assessment of pneumonia

The patient's history is an important part of the diagnosis of pneumonia. The patient should be sure to report any of the following:
1. recent or chronic respiratory infection,
2. exposure to people with pneumonia or other respiratory illnesses (such as tuberculosis),
3. history of smoking,
4. alcohol or drug abuse,
5. recent travel, and
6. Occupational risks.
7. Lung cancer
8. Diabetes mellitus , AIDS ,dust , chemical toxins ,
9. COPD
10. Anorexia , nausia , vomiting , chills
11. Chest pain , headache , muscle aches
12. Dyspnia , cough , nasal congestion
13. cough with mucus-like, greenish, or pus-like sputum
14. chills with shaking
15. fever
16. easy fatigue
17. chest pain
18. sharp or stabbing
19. increased by deep breathing
20. increased by coughing
21. headache
22. loss of appetite
23. nausea and vomiting
24. general discomfort, uneasiness, or ill feeling (malaise(
25. joint stiffness (rare(
26. muscular stiffness (rare(
27. Additional symptoms that may be associated with this disease:
28. shortness of breath
29. excessive sweating
30. clammy skin
31. nasal flaring
32. coughing up blood
33. rapid breathing
34. anxiety, stress, and tension
35. abdominal pain





Physical assessment
HOW IS PNEUMONIA DIAGNOSED?
In many cases of mild-to-moderate community-acquired pneumonia, the physician is able to diagnose and treat pneumonia based solely on a history and physical examination. Often, however, a diagnosis is not straightforward, particularly in hospitalized patients.
Physical Examination
Use of the Stethoscope. The most important diagnostic tool for pneumonia is the stethoscope. Sounds in the chest that may indicate pneumonia are the following:
• Rales (a bubbling or crackling sound). Rales on one side of the chest and rales heard while the patient is lying down is strongly suggestive of pneumonia.
• Rhonchi (abnormal rumblings indicating the presence of thick fluid).
Percussion. The physician will also use a test called percussion, in which he or she taps the chest lightly. A dull thud instead of a healthy hollow-drum-like sound indicates certain conditions that suggest pneumonia, including the following:
• Consolidation (a condition, in which the lung becomes firm and inelastic).
• Pleural effusion (fluid build-up in the space between the lungs and the lining around it).
Laboratory Tests for Diagnosing Infection and Identifying Bacterial Agents
Although antibiotics are available that can destroy a wide spectrum of organisms, it would be preferable to use an antibiotic that can target the specific microorganism causing the pneumonia. Researchers, then, are looking for laboratory tests that would identify the specific organism or virus causing the pneumonia. Unfortunately, people harbor many bacteria, and sputum and blood tests are not always effective in distinguishing between harmless and harmful microscopic agents. In severe cases, physicians particularly need to use invasive diagnostic measures to identify the infecting agent.

Urine Tests. A urine test (NOW) is up to 93% accurate in identifying S. pneumoniae within 15 minutes. However, a 2000 study indicated that it is not likely to be useful in diagnosing S. pneumoniae as a cause of pneumonia in children, since the organism is very common in the noses and throats of children. This organism, then, would very likely be picked up by the test even if it were not the cause of the pneumonia.

Sputum Tests. Only a sample of sputum coughed from the lungs will yield the infecting organism, and, even then, tests are not always successful in revealing the culprit. The following steps may be required:
• The physician first asks the patient to cough as deeply as possible to produce an adequate sputum sample. A shallow cough produces a sample that usually only contains normal mouth bacteria.
• A patient who is not able to cough sufficiently may be asked to inhale a saline spray that helps produce an adequate sputum sample.
• In some cases, a tube will be inserted through the nose down into the lower respiratory tract to induce a deeper cough.
Even before sending the sample to the laboratory, the physician will check it for the following:
• Presence of blood (an indication of infection).
• Color and consistency. If the sputum is opaque and colored yellow, green, or brown, then infection is likely. Clear, white, glistening sputum indicates no infection.
In the laboratory, the sputum sample may be used as follows:
• A Gram's stain is made, which may reveal the presence of bacteria and whether they are gram-negative or positive.
• A sputum culture may be performed, in which organisms are grown in the laboratory.
Blood Tests. Blood tests may be used for the following:
• White blood cell count. High levels indicate infection.
• Blood cultures. They may be performed for detecting the specific organism causing the pneumonia, but are not often helpful in distinguishing harmful from harmless organisms. They are accurate in only 10% to 30% of cases, and their use should generally be limited to severe cases.
• Detection of antibodies to S. pneumoniae. Researchers are using specialized techniques to detect antibodies to S. pneumoniae (immune factors that target specific foreign invaders), but it is not clear if they are accurate.
Chest X-Rays and Other Imaging Techniques
X-Rays. A chest x-ray is nearly always taken to confirm a diagnosis of pneumonia. It may reveal the following:
• White areas in the lung called infiltrates, which indicate infection.
• Complications of pneumonia, including pleural effusions (fluid around the lungs) and abscesses.
Other Imaging Tests. Computed tomography (CT) scans or MRIs may be obtained in the following circumstances:
• If x-ray results are unclear.
• When patients do not respond to antibiotics.
• When patients have complications.
• When patients have other serious health problems.
These more sophisticated imaging techniques can help detect the presence of tissue damage, abscesses, and enlarged lymph nodes. They can also detect some tumors that block bronchial tubes. No imaging technique can determine the actual organism causing the infection.
Invasive Diagnostic Procedures
Invasive diagnostic procedures may be required in the following circumstances:
• When patients have life-threatening complications.
• When patients have failed standard treatments for no known reason.
• When AIDS or other immune problems are present.
Each of the procedures has potential complications and is not used under ordinary conditions.

Thoracentesis. If a physician detects pleural effusion and suspects that empyema (pus) is present, thoracentesis is performed:
• Fluid in the pleura is withdrawn using a long thin needle inserted between the ribs.
• The fluid is then tested using blood cell counts, Gram stains, cultures, and chemical tests.
Complications of this procedure include collapsed lung, bleeding, and introduction of infection.

Bronchoscopy. A bronchoscopy employs the following:
• The patient is given a local anesthetic, supplementary oxygen, and sedatives.
• The physician inserts a fiberoptic tube into the lower respiratory tract through the nose or mouth.
• The tube acts like a telescope into the body, allowing the physician to view the wind-pipe and major airways for pus, abnormal mucus, or other problems.
• The doctor removes specimens for analysis and can also treat the patient by removing any foreign bodies or infected tissue encountered during the process.
• Bronchoalveolar lavage (BAL) may be employed. This involves injecting high amounts of saline through the bronchoscope into the lung and then immediately suctioning the fluid back, which is then analyzed in the laboratory. Studies find BAL to be an effective method for detecting specific infection-causing organisms in patients with serious pneumonia.
The procedure is usually very safe, but complications can occur. They include allergic reactions to the sedatives or anesthetics, asthma attacks in susceptible patients, and bleeding. Fever may follow the procedure.

Lung Biopsy. In very severe cases of pneumonia or when the diagnosis is unclear in specific cases, particularly in patients with damaged immune systems, a lung biopsy may be required. Biopsies can be performed in one of two ways:
• A Lung Tap. This procedure typically uses a needle inserted between the ribs to draw fluid out of the lung for analysis. It is known by a number of names including lung aspiration, lung puncture, thoracic puncture, transthoracic needle aspiration, percutaneous needle aspiration, and needle aspiration. It is a very old procedure that is not done often any more, particularly in children, since it is invasive and poses a slight risk for collapsed lung. Some experts argue, however, that a lung tap offers a more accurate solution than other methods for identifying bacteria and the risk it poses is slight. Given the increase in resistant bacteria, they believe its use should be reappraised in young people.
• Surgically (thoracotomy), using general anesthesia and an incision. This is used for diagnosis only in very severe cases. As with bronchoscopy, the procedure can also be used to treat the patient, removing damaging lung tissue and, in severe cases, removing the entire lobe (lobectomy). (In such cases, remaining lung tissue re-expands after surgery to compensate for any removed tissue.)