Sandbox/cap: Difference between revisions

Pneumonia Main Page
	Community-Acquired Pneumonia Microchapters
Home
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Community-acquired pneumonia from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Severity Criteria
History and Symptoms
Physical Examination
Laboratory Findings
Chest X Ray
CT
Ultrasound
Other Diagnostic Studies
Treatment
Hospital Admission Decision
Medical Therapy
Primary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Sandbox/cap On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Sandbox/cap All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Sandbox/cap
CDC on Sandbox/cap
Sandbox/cap in the news
Blogs on Sandbox/cap
Directions to Hospitals Treating Community-acquired pneumonia
Risk calculators and risk factors for Sandbox/cap

VisualWikitext

Revision as of 17:03, 17 February 2014

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]

Pathophysiology

Diminished Mucociliary Clearance

The cilia lining the respiratory epithelium serve to move secreted mucus containing trapped foreign particles including pathogens towards the oropharynx for either expectoration or swallowing. Elevated incidence of pneumonia in patients with genetic defects affecting mucociliary clearance suggests its role in the pathogenesis.

Cough Suppression

Cough, together with mucociliary clearance, prevent pathogens from entering the lower respiratory tract. Cough suppression or cough reflex inhibition seen in patients with cerebrovascular accidents and drug overdosages is associated with an enhanced risk for aspiration pneumonia.

Another relation to cough is genetic polymorphisms in the angiotensin-converting enzyme (ACE) gene. The role of cough in preventing pneumonia may be explained by a higher risk for developing pneumonia in homozygotes carrying deletion/deletion (DD) genotype who are found to have lower levels of bradykinin and tachykinins such as substance P.^[1]^[2]

References

↑ Morimoto, S.; Okaishi, K.; Onishi, M.; Katsuya, T.; Yang, J.; Okuro, M.; Sakurai, S.; Onishi, T.; Ogihara, T. (2002). "Deletion allele of the angiotensin-converting enzyme gene as a risk factor for pneumonia in elderly patients". Am J Med. 112 (2): 89–94. PMID 11835945. Unknown parameter |month= ignored (help)
↑ Rigat, B.; Hubert, C.; Alhenc-Gelas, F.; Cambien, F.; Corvol, P.; Soubrier, F. (1990). "An insertion/deletion polymorphism in the angiotensin I-converting enzyme gene accounting for half the variance of serum enzyme levels". J Clin Invest. 86 (4): 1343–6. doi:10.1172/JCI114844. PMID 1976655. Unknown parameter |month= ignored (help)

[Morimoto-2002-1] Morimoto, S.; Okaishi, K.; Onishi, M.; Katsuya, T.; Yang, J.; Okuro, M.; Sakurai, S.; Onishi, T.; Ogihara, T. (2002). "Deletion allele of the angiotensin-converting enzyme gene as a risk factor for pneumonia in elderly patients". Am J Med. 112 (2): 89–94. PMID 11835945. Unknown parameter |month= ignored (help)

[2] Rigat, B.; Hubert, C.; Alhenc-Gelas, F.; Cambien, F.; Corvol, P.; Soubrier, F. (1990). "An insertion/deletion polymorphism in the angiotensin I-converting enzyme gene accounting for half the variance of serum enzyme levels". J Clin Invest. 86 (4): 1343–6. doi:10.1172/JCI114844. PMID 1976655. Unknown parameter |month= ignored (help)

[1]

[2]

@@ Line 4: / Line 4: @@
 ==Pathophysiology==
-==Overview==
-[[Pneumonia]] can be transmitted by various methods. The etiology depends upon various factors like age, immune status, geographical area, and comorbid conditions. The transmission can be systemic , local , trauma or iatrogenic. It could also be due to decreased immunity or inability to filter out pathogen.
-===Modes of transmission===
+====Diminished Mucociliary Clearance====
-=====1.Microaspiration of oropharyngeal contents=====
-Inoculation of lung by pathogenetic organisms is one of the mechanism of acquiring pneumonia.  It most commonly occurs in normal persons during sleep , in unconscious persons due to impaired gag reflex, cough reflex or gastroesopahegeal reflux.<ref name="Wunderink-2004">{{Cite journal  | last1 = Wunderink | first1 = RG. | last2 = Waterer | first2 = GW. | title = Community-acquired pneumonia: pathophysiology and host factors with focus on possible new approaches to management of lower respiratory tract infections. | journal = Infect Dis Clin North Am | volume = 18 | issue = 4 | pages = 743-59, vii | month = Dec | year = 2004 | doi = 10.1016/j.idc.2004.07.004 | PMID = 15555822 }}</ref>
-=====2.Inhalation of aerosolized droplets=====
+The [[Respiratory epithelium#Ciliary Escalator|cilia]] lining the [[respiratory epithelium]] serve to move secreted [[mucus]] containing trapped foreign particles including pathogens towards the [[oropharynx]] for either expectoration or swallowing. Elevated incidence of [[pneumonia]] in patients with genetic defects affecting [[mucociliary clearance]] suggests its role in the pathogenesis.
-Inhalation of aerosolized droplets of 0.5 to 1 micrometer is the most common pathway of acquiring pneumonia. A few bacterial and viral infections are transmitted in this fashion.  The lung can normally filter out particles between 0.5 to 2  micrometer by recruiting the [[alveolar macrophages]].<ref name="Wunderink-2004">{{Cite journal  | last1 = Wunderink | first1 = RG. | last2 = Waterer | first2 = GW. | title = Community-acquired pneumonia: pathophysiology and host factors with focus on possible new approaches to management of lower respiratory tract infections. | journal = Infect Dis Clin North Am | volume = 18 | issue = 4 | pages = 743-59, vii | month = Dec | year = 2004 | doi = 10.1016/j.idc.2004.07.004 | PMID = 15555822 }}</ref>
-=====3.Blood borne or sytemic infection=====
+====Cough Suppression====
-Another way of acquiring pneumonia systematically is through blood.  Blood-borne pneumonia is more common in intravenous drug users . [[Staphylococcal aureus]] causes pneumonia in this way. Gram negative bacteria are found to cause pneumonia in immunocompromised individuals.
+[[Cough]], together with [[mucociliary clearance]], prevent pathogens from entering the lower [[respiratory tract]]. Cough suppression or [[cough reflex]] inhibition seen in patients with [[cerebrovascular accident]]s and [[overdose|drug overdosage]]s is associated with an enhanced risk for [[aspiration pneumonia]].
+Another relation to [[cough]] is [[genetic polymorphism]]s in the [[angiotensin-converting enzyme|angiotensin-converting enzyme (ACE)]] gene. The role of [[cough]] in preventing [[pneumonia]] may be explained by a higher risk for developing [[pneumonia]] in [[homozygote]]s carrying [[deletion]]/[[deletion]] (DD) [[genotype]] who are found to have lower levels of [[bradykinin]] and [[tachykinins]] such as [[substance P]].<ref name="Morimoto-2002">{{Cite journal  | last1 = Morimoto | first1 = S. | last2 = Okaishi | first2 = K. | last3 = Onishi | first3 = M. | last4 = Katsuya | first4 = T. | last5 = Yang | first5 = J. | last6 = Okuro | first6 = M. | last7 = Sakurai | first7 = S. | last8 = Onishi | first8 = T. | last9 = Ogihara | first9 = T. | title = Deletion allele of the angiotensin-converting enzyme gene as a risk factor for pneumonia in elderly patients. | journal = Am J Med | volume = 112 | issue = 2 | pages = 89-94 | month = Feb | year = 2002 | doi =  | PMID = 11835945 }}</ref><ref>{{Cite journal  | last1 = Rigat | first1 = B. | last2 = Hubert | first2 = C. | last3 = Alhenc-Gelas | first3 = F. | last4 = Cambien | first4 = F. | last5 = Corvol | first5 = P. | last6 = Soubrier | first6 = F. | title = An insertion/deletion polymorphism in the angiotensin I-converting enzyme gene accounting for half the variance of serum enzyme levels. | journal = J Clin Invest | volume = 86 | issue = 4 | pages = 1343-6 | month = Oct | year = 1990 | doi = 10.1172/JCI114844 | PMID = 1976655 }}</ref>
-=====4.Trauma or Local spread=====
-Pneumonia can be caused iatrogenically by a surgeon during an operative procedure or by a penetrating trauma to the lung.  A local spread of a hepatic abscess and amoebic abscess can also lead to pneumonia.
-===Pathogenetic mechanism===
-The lung can normally filter out large droplets of aerosols. Smaller droplets of the size of 0.5 to 2 micrometer are deposited on the alveoli and then engulfed by alevolar macrophages. These macrophages release cytokines and chemokines , which also includes  [[Tumor necrosis factor-alpha]], [[interleukin]]-8 and [[leukotriene]]B4 . The neutrophils are recruited by these cells and they kill these micro-organisms.<ref name="Strieter-2003">{{Cite journal  | last1 = Strieter | first1 = RM. | last2 = Belperio | first2 = JA. | last3 = Keane | first3 = MP. | title = Host innate defenses in the lung: the role of cytokines. | journal = Curr Opin Infect Dis | volume = 16 | issue = 3 | pages = 193-8 | month = Jun | year = 2003 | doi = 10.1097/01.qco.0000073766.11390.0e | PMID = 12821807 }}</ref><ref name="Mason-2005">{{Cite journal  | last1 = Mason | first1 = CM. | last2 = Nelson | first2 = S. | title = Pulmonary host defenses and factors predisposing to lung infection. | journal = Clin Chest Med | volume = 26 | issue = 1 | pages = 11-7 | month = Mar | year = 2005 | doi = 10.1016/j.ccm.2004.10.018 | PMID = 15802161 }}</ref>
 ==References==