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| {{xyz}} | | {{xyz}} |
| {{CMG}}; {{AE}} | | {{CMG}}; {{AE}} |
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| ==Overview== | | ==Overview== |
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| ==Classification== | | ==Classification== |
| [[Atelectasis]] may be classified based on etiology into [[Obstruction|obstructive]] and non-obstructive types. Obstructive atelectasis, which is the most common type of atelectasis may develop due to [[obstruction]] by [[foreign bodies]], [[Tumor|tumors]] and mucus plugs. Causes of non obstructive atelectasis include lung [[Scar|scarring]] caused by necrotizing [[pneumonia]] or [[Sarcoidosis|granulomatous diseases]], lung infiltration, extrinsic lung compression and diminished levels of [[Pulmonary surfactant|surfactant]]. Atelectasis may also be classified based on duration into acute and chronic types. Acute atelectasis is associated with airlessness due to recent lung collapse while chronic atelectasis involves a combination of [[infection]], [[Bronchiole|bronchial]] destruction, and [[fibrosis]], in adition to airlessness.
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| ==Pathophysiology== | | ==Pathophysiology== |
| The pathophysiology of obstructive and non-obstructive atelectasis is determined by several factors. Obstructive atelectasis, the most common type of atelectasis and occurs due to obstruction from the [[Vertebrate trachea|trachea]] to the [[Pulmonary alveolus|alveoli]] at any level. [[Foreign bodies]], [[Tumor|tumors]], and [[Mucus|mucus plugs]] are causes of obstructive atelectasis. Non obstructive atelectasis occurs due to severe lung scarring caused by [[Pneumonia|necrotizing pneumonias]] or [[Granulomatous|granulomatous diseases]] leading to cicatrisation atelectasis. Lung infiltration by a [[tumor]] ([[bronchoalveolar carcinoma]]) may cause replacement atelectasis, thoracic space occupying lesions can cause compression atelectasis, diminished levels of [[Pulmonary surfactant|surfactant]] can lead to adhesive atelectasis presenting as [[Acute respiratory distress syndrome|ARDS]]. Passive atelectasis occurs due to absence of contact between the [[Parietal pleura|parietal]] and [[Visceral pleura|visceral pleurae]] due to fluid ([[pleural effusion]]), air ([[pneumothorax]]), blood ([[hemothorax]]) etc. Patients undergoing upper abdominal and thoracic procedures may develop postoperative atelectasis which may arise as a complication of surgery or [[Anesthesia|anaesthesia]] leading to decreased surfactant activity and dysfunction of the [[Thoracic diaphragm|diaphragm]].
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| ==Causes== | | ==Causes== |
| The most common cause of atelectasis is postoperative atelectasis, due to the effect of surgical manipulation or [[general anaesthesia]] on the patient. Obstructive atelectasis mostly develops due to blockage within the [[bronchiole]] or [[bronchus]], which may be within the [[airway]] (foreign bodies, mucus plugs), arising from the wall (tumors such as [[squamous cell carcinoma]]) or space occupying lesions within the [[thoracic cavity]] ([[tumor]], [[lymph node]], [[Tuberculosis|tubercle]]). Causes of non-obstructive atelectasis include impaired [[pulmonary surfactant|surfactant]] formation or activation, leading to alveolar collapse due to increased [[surface tension]].
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| ==Differentiating Hereditary pancreatitis from Other Diseases== | | ==Differentiating Xyz from Other Diseases== |
| Atelectasis must be differentiated from other diseases that cause acute [[dyspnea]], [[fever]], and [[chest pain]], such as [[asthma]], [[bronchitis]], and [[interstitial lung disease]].
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| ==Epidemiology and Demographics== | | ==Epidemiology and Demographics== |
| The incidence and prevalence of atelectasis are not known. Patients of all age groups may develop atelectasis. Rounded atelectasis commonly affects individuals at sixty years of age. Atelectasis affects men and women equally.
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| ==Risk Factors== | | ==Risk Factors== |
| [[Chest trauma]], [[general anaesthesia]], [[thoracic surgery]], [[cystic fibrosis]], [[Premature birth|prematurity]] and [[Acute respiratory distress syndrome|respiratory distress syndrome]] are some of the common risk factors that predispose patients to developing atelectasis. Children less than three years of age and adults over sixty years of age are also at increased risk of [[Alveolus|alveolar]] collapse and impaired [[Pulmonary surfactant|surfactant]] production in response to pulmonary stressors such as [[Toxin|toxins]], [[Oxygen toxicity|hyperoxia]], [[Hypoxemia|hypoxia]] and [[ischemia]].
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| ==Screening== | | ==Screening== |
| There is insufficient evidence to recommend routine screening for atelectasis.
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| ==Natural History, Complications, and Prognosis== | | ==Natural History, Complications, and Prognosis== |
| If left untreated, atelectasis may be fatal in [[Patient|patients]] and progress to [[pneumonia]], [[sepsis]], and [[respiratory failure]]. Common complications of atelectasis include [[pneumonia]], [[bronchiectasis]], [[hypoxemia]], [[respiratory failure]], and [[sepsis]]. Depending on the extent of [[lung]] involvement at the time of diagnosis, the [[prognosis]] may vary. However, the [[prognosis]] is generally regarded as good. Involvement of a small portion of the [[lung]] is not associated with life threatening complications, as the remaining [[lung]] compensates for the [[hypoxemia]]. However, atelectasis is associated with poor [[prognosis]] if the surface area of [[lung]] involvement is very large, in the presence of pre-existing [[lung]] disease, in case of failure to remove [[obstruction]] and in case of atelectasis due to [[cancer]].
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| ==Diagnosis== | | ==Diagnosis== |
| | ===Diagnostic Study of Choice=== |
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| ===History and Symptoms=== | | ===History and Symptoms=== |
| The majority of patients with atelectasis are asymptomatic. Common symptoms of atelectasis include [[Dyspnea|breathlessness]], [[chest pain]], and [[cyanosis]]. Symptoms in patients with atelectasis depend upon rapidity of [[Bronchiole|bronchial]] occlusion, lung area affected and presence of any overlying [[infection]].
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| ===Physical Examination=== | | ===Physical Examination=== |
| Patients with atelectasis usually have non specific signs on physical examination. Physical examination of patients with atelectasis is usually remarkable for decreased [[Respiratory examination|chest expansion]], mediastinal displacement towards the affected side and elevation of the [[Thoracic diaphragm|diaphragm]]. Patients may develop dullness to percussion over the involved area, [[Wheeze|wheezing]] and diminished or absent breath sounds on [[auscultation]].
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| ===Laboratory Findings=== | | ===Laboratory Findings=== |
| Patients with atelectasis have [[hypoxemia]] with low levels of PaO2 and normal/low PaCO2 levels on ABG analysis. Raised [[Peak airway pressure|peak and end-inspiratory plateau pressures]] due to decreased lung compliance are also present in these patients.
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| | ===Electrocardiogram=== |
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| ===X-ray=== | | ===X-ray=== |
| An x-ray may be helpful in the diagnosis of atelectasis. Findings on an x-ray suggestive of atelectasis include [[displacement]] of [[Fissure|fissures]], [[rib]] crowding, elevation of ipsilateral [[Thoracic diaphragm|diaphragm]], volume loss on ipsilateral hemithorax, [[Hilum|hilar]] displacement and compensatory hyperlucency of the remaining lobes. Complete lung atelectasis and atelectasis involving different parts of the lung have their own characteristic appearance. While complete atelectasis of the lung may lead to opacification of the entire hemithorax and ipsilateral shift of the [[mediastinum]], a right middle and lower lobe atelectasis may show [[Pleural effusions|subpulmonic effusions]] along with right [[Thoracic diaphragm|hemidiaphragmatic]] elevation on X-ray.
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| ===Ultrasound=== | | ===Echocardiography and Ultrasound=== |
| There are no significant ultrasound findings associated with atelectasis.
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| ===CT scan=== | | ===CT scan=== |
| CT findings suggestive of atelectasis include [[Hilum|hilar]] displacement, elevation of ipsilateral [[Thoracic diaphragm|diaphragm]], rib crowding, [[displacement]] of [[Fissure|fissures]], and compensatory hyperlucency of the remaining [[Lung|lobes]]. CT findings associated with complete atelectasis of an entire [[lung]] include opacification of the entire hemithorax and ipsilateral shift of the [[mediastinum]]. Collapse of different parts of the lung have their own characteristic appearance. For example, a collapsed right middle lobe has a tilted icecream sign which appears as a triangular [[opacity]] against the border of the right heart with a laterally pointed apex. On the other hand, RUL collapse appears as a right paratracheal opacity, with a concave lateral appearance of the [[Fissure|minor lung fissure]].
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| ===MRI=== | | ===MRI=== |
| MRI may be helpful in distinguishing obstructive causes of atelectasis from non-obstructive causes. MRI does not play a significant role in the diagnosis of atelectasis.
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| ===Other Imaging Findings=== | | ===Other Imaging Findings=== |
| There are no other imaging findings associated with atelectasis.
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| ===Other Diagnostic Studies=== | | ===Other Diagnostic Studies=== |
| [[Bronchoscopy|Flexible fibreoptic bronchoscopy]] may be helpful in the diagnosis of atelectasis. This technique assists in determining the cause of [[obstruction]] and removal of [[Mucus|mucus plugs]]. [[Biopsy|Biopsies]] taken during [[Bronchoscopy|fiberoptic bronchoscopy]] helps in the diagnosis of [[Cancer|malignancy]] and [[allergic bronchopulmonary aspergillosis]].
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| ==Treatment== | | ==Treatment== |
| ===Medical Therapy=== | | ===Medical Therapy=== |
| The primary treatment for atelectasis is management of the underlying cause. Besides this, supportive therapy for atelectasis includes [[chest physiotherapy]], [[breathing]] and [[Coughing|coughing exercises]], [[Ambulation|early ambulation]], [[Suction|nasotracheal suctioning,]] [[Humidifier Lung|humidifiers]], nebulized [[Bronchodilator|bronchodilators]] and supplemental [[oxygen]] in order to maintain an [[Oxygen saturation|arterial oxygen saturation]] of greater than 90 percent. [[Intubation]], mechanical support, [[positive pressure ventilation]] and [[Positive airway pressure|continous positive airway pressure (CPAP)]] help in the prevention of [[Alveolus|alveolar]] collapse, thereby assisting in lung inflation in patients with atelectasis.
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| | === Interventions === |
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| ===Surgery=== | | ===Surgery=== |
| Surgical intervention is not recommended for the management of atelectasis.
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| ===Primary Prevention=== | | ===Primary Prevention=== |
| Judicious use of [[Anaesthetic agent|anaesthetic agents]] known to cause narcosis, use of [[epidural analgesia]] in patients with underlying [[pulmonary disease]], [[Spirometry|incentive spirometry]], early [[Walking|ambulation]], [[Humidifier Lung|humidifiers]], breathing exercises, coughing exercises and supplemental oxygen are effective measures of primary prevention in patients undergoing operative procedures, in order to prevent post operative atelectasis.
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| ===Secondary Prevention=== | | ===Secondary Prevention=== |
| Effective measures for the secondary prevention of atelectasis include [[Spirometry|incentive spirometry]], [[Breathing|deep breathing exercises]], [[Coughing|coughing exercises]] and early [[Walking|ambulation]]. These measures help prevent complications in patients such as [[Infection|post obstructive infection]], [[bronchiectasis]] and [[fibrosis]].
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| ==References== | | ==References== |
| {{reflist|2}} | | {{reflist|2}} |