Atelectasis


Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange It may affect part or all of a lung1 It is usually not bilateral It is a condition where the alveoli are deflated down to little or no volume, as distinct from pulmonary consolidation, in which they are filled with liquid It is often called a collapsed lung, although that term may also refer to pneumothorax2

It is a very common finding in chest x-rays and other radiological studies, and may be caused by normal exhalation or by various medical conditions Although frequently described as a collapse of lung tissue, atelectasis is not synonymous with a pneumothorax, which is a more specific condition that features atelectasis Acute atelectasis may occur as a post-operative complication or as a result of surfactant deficiency In premature neonates, this leads to infant respiratory distress syndrome The term uses combining forms of atel- + ectasis, from Greek: ἀτελής, "incomplete" + ἔκτασις, "extension"

Contents

  • 1 Signs and symptoms
  • 2 Causes
  • 3 Diagnosis
    • 31 Classification
      • 311 Absorption resorption atelectasis
        • 3111 Compression relaxation atelectasis
        • 3112 Cicatrization contraction atelectasis
      • 312 Chronic atelectasis
        • 3121 Right middle lobe syndrome
        • 3122 Rounded atelectasis
  • 4 Treatment
  • 5 See also
  • 6 References
  • 7 External links

Signs and symptomsedit

Atelectasis

May have no signs and symptoms or they may include:3

  • cough, but not prominent;
  • chest pain not common;
  • breathing difficulty fast and shallow;
  • low oxygen saturation;
  • pleural effusion transudate type;
  • cyanosis late sign;
  • increased heart rate

It is a common misconception that atelectasis causes fever A study of 100 post-op patients followed with serial chest X-rays and temperature measurements showed that the incidence of fever decreased as the incidence of atelectasis increased4 A recent review article summarizing the available published evidence on the association between atelectasis and post-op fever concluded that there is no clinical evidence supporting this doctrine5

Causesedit

The most common cause is post-surgical atelectasis, characterized by splinting, ie restricted breathing after abdominal surgery Another common cause is pulmonary tuberculosis Smokers and the elderly are also at an increased risk Outside of this context, atelectasis implies some blockage of a bronchiole or bronchus, which can be within the airway foreign body, mucus plug, from the wall tumor, usually squamous cell carcinoma or compressing from the outside tumor, lymph node, tubercle Another cause is poor surfactant spreading during inspiration, causing the surface tension to be at its highest which tends to collapse smaller alveoli Atelectasis may also occur during suction, as along with sputum, air is withdrawn from the lungs There are several types of atelectasis according to their underlying mechanisms or the distribution of alveolar collapse; resorption, compression, microatelectasis and contraction atelectasis

Diagnosisedit

Atelectasis of the right lower lobe seen on chest X-ray

Clinically significant atelectasis is generally visible on chest X-ray; findings can include lung opacification and/or loss of lung volume Post-surgical atelectasis will be bibasal in pattern Chest CT or Bronchoscopy may be necessary if the cause of atelectasis is not clinically apparent Direct signs of atelectasis include displacement of interlobar fissures and mobile structures within the thorax, overinflation of the unaffected ipsilateral lobe or contralateral lung, and opacification of the collapsed lobe

Classificationedit

Atelectasis of the middle lobe on a sagittal CT reconstruction

Atelectasis may be an acute or chronic condition In acute atelectasis, the lung has recently collapsed and is primarily notable only for airlessness In chronic atelectasis, the affected area is often characterized by a complex mixture of airlessness, infection, widening of the bronchi bronchiectasis, destruction, and scarring fibrosis

Absorption resorption atelectasisedit

The atmosphere is composed of 78% nitrogen and 21% oxygen Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood, reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis6

Compression relaxation atelectasisedit

It is usually associated with accumulation of blood, fluid, or air within the pleural cavity, which mechanically collapses the lung This is a frequent occurrence with pleural effusion, caused by congestive heart failure CHF Leakage of air into the pleural cavity pneumothorax also leads to compression atelectasis7

Cicatrization contraction atelectasisedit

It occurs when either local or generalized fibrotic changes in the lung or pleura hamper expansion and increase elastic recoil during expiration8 Causes include granulomatous disease, necrotising pneumonia and radiation fibrosis9

Chronic atelectasisedit

Chronic atelectasis may take one of two forms—middle lobe syndrome or rounded atelectasis

Right middle lobe syndromeedit

In right middle lobe syndrome, the middle lobe of the right lung contracts, usually because of pressure on the bronchus from enlarged lymph glands and occasionally a tumor The blocked, contracted lung may develop pneumonia that fails to resolve completely and leads to chronic inflammation, scarring, and bronchiectasis

Rounded atelectasisedit

In rounded atelectasis Folded lung or Blesovsky syndrome10, an outer portion of the lung slowly collapses as a result of scarring and shrinkage of the membrane layers covering the lungs pleura, which would show as visceral pleural thickening and entrapment of lung tissue This produces a rounded appearance on x-ray that doctors may mistake for a tumor Rounded atelectasis is usually a complication of asbestos-induced disease of the pleura, but it may also result from other types of chronic scarring and thickening of the pleura

Treatmentedit

Treatment is directed at correcting the underlying cause Post-surgical atelectasis is treated by physiotherapy, focusing on deep breathing and encouraging coughing An incentive spirometer is often used as part of the breathing exercises Walking is also highly encouraged to improve lung inflation People with chest deformities or neurologic conditions that cause shallow breathing for long periods may benefit from mechanical devices that assist their breathing One method is continuous positive airway pressure, which delivers pressurized air or oxygen through a nose or face mask to help ensure that the alveoli do not collapse, even at the end of a breath This is helpful, as partially inflated alveoli can be expanded more easily than collapsed alveoli Sometimes additional respiratory support is needed with a mechanical ventilator

The primary treatment for acute massive atelectasis is correction of the underlying cause A blockage that cannot be removed by coughing or by suctioning the airways often can be removed by bronchoscopy Antibiotics are given for an infection Chronic atelectasis is often treated with antibiotics because infection is almost inevitable In certain cases, the affected part of the lung may be surgically removed when recurring or chronic infections become disabling or bleeding is significant If a tumor is blocking the airway, relieving the obstruction by surgery, radiation therapy, chemotherapy, or laser therapy may prevent atelectasis from progressing and recurrent obstructive pneumonia from developing

See alsoedit

  • Alveolar capillary dysplasia, a very rare type of diffuse congenital disorder of the lung
  • Tympanic membrane atelectasis: Retraction of the ear drum into the middle ear can also be referred to as atelectasis
  • Flat-chested kitten syndrome or FCKS: atelectasis in neo-natal kittens

Referencesedit

  1. ^ Wedding, Mary Ellen; Gylys, Barbara A 2005 Medical Terminology Systems: A Body Systems Approach: A Body Systems Approach Philadelphia, Pa: F A Davis Company ISBN 0-8036-1289-3 
  2. ^ Orenstein, David M 2004 Cystic Fibrosis: A Guide for Patient and Family Lippincott Williams & Wilkins p 62 ISBN 9780781741521 
  3. ^ "Atelectasis" MayoClinic Retrieved 20 February 2017 
  4. ^ Engoren M January 1995 "Lack of association between atelectasis and fever" Chest 107 1: 81–4 PMID 7813318 doi:101378/chest107181 
  5. ^ Mavros MN, Velmahos GC, Falagas ME 2011 "Atelectasis as a cause of postoperative fever: where is the clinical evidence" Chest 140 2: 418–24 PMID 21527508 doi:101378/chest11-0127 
  6. ^ White, Gary C 2002 Basic Clinical Lab Competencies for Respiratory Care, 4th ed Delmar Cengage Learning p 230 ISBN 978-0-7668-2532-1 
  7. ^ Robbins 2013 Basic Pathology ELSEVIER p 460 ISBN 978-1-4377-1781-5 
  8. ^ Robbins 2013 Basic Pathology ELSEVIER p 460 ISBN 978-1-4377-1781-5 
  9. ^ Sheikh, Zishan; Weerakkody, Yuranga "Lung atelectasis" Radiopaedia Retrieved 20 February 2017 
  10. ^ "Round atelectasis" Radiopaedia Retrieved 20 February 2017 

External linksedit

Classification
  • ICD-10: J981
  • ICD-9-CM: 5180
  • MeSH: D001261
  • DiseasesDB: 10940
External resources
  • MedlinePlus: 000065
  • eMedicine: med/180



  • 04-048a at Merck Manual of Diagnosis and Therapy Home Edition
  • Atelectasis at Merck Manual of Diagnosis and Therapy Professional Edition


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