Materiały źródłowe

• #1 Atelectasis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK545316/

  Atelectasis occurs due to the partial or complete, reversible collapse of the small airways, resulting in impaired exchange of CO2 and O2, causing an intrapulmonary shunt (perfusion without ventilation). […] Both obstructive and nonobstructive atelectasis occur by any single or combination of 3 different pathophysiologic mechanisms: increased pleural pressure, low alveolar pressure, and surfactant impairment. […] Obstructive (resorptive) atelectasis results from airway obstructions that prevent air from reaching the alveoli, and air distal to the obstruction is reabsorbed from the nonventilated alveoli, leading to the collapse of the airways. […] Compression atelectasis is caused by increased external pressure on the lung. […] Surfactant-related atelectasis (adhesive atelectasis) occurs due to surfactant impairment.

• #1 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface tension overcome expanding forces from alveolar pressure and parenchymal tethering. […] It is increasingly recognized that it can also induce local tissue biological responses, such as inflammation, local immune dysfunction, and damage of the alveolar-capillary barrier, with potential loss of lung fluid clearance, increased lung protein permeability and susceptibility to infection, factors that can initiate or exaggerate lung injury. […] Mechanical ventilation of a heterogeneously-aerated lung (e.g., in the presence of atelectatic lung tissue) involves biomechanical processes that may precipitate further lung damage: concentration of mechanical forces, propagation of gas-liquid interfaces, and remote overdistension.

• #1 Atelectasis: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/296468-overview

  Atelectasis is a partial or complete collapse of the entire lung or a specific area, or lobe, of the lung, leading to impaired exchange of carbon dioxide and oxygen. Atelectasis occurs when the alveoli (small air sacs) within the lung become deflated or fill with alveolar fluid. […] The primary cause of acute or chronic atelectasis is bronchial obstruction by plugs of tenacious sputum; foreign bodies; endobronchial tumors; or tumors, a lymph node, or an aneurysm compressing the bronchi and causing bronchial distortion. […] Following obstruction of a bronchus, the blood circulating in the alveolar-capillary membrane absorbs the gas from alveoli. This process can lead to retraction of the lung and an airless state within those alveoli in a few hours. […] The loss of contact between the visceral and parietal pleurae is the primary cause of nonobstructive atelectasis.

• #1 Atelectasis: Types and pathogenesis in adults – UpToDate

  https://www.uptodate.com/contents/atelectasis-types-and-pathogenesis-in-adults/print

  Obstruction of a segmental bronchus is less likely to result in segmental atelectasis than obstruction of a lobar bronchus is to produce lobar atelectasis. This difference is the consequence of collateral ventilation between segments within a lobe. Collateral ventilation occurs via three distinct channels (the pores of Kohn, canals of Lambert, and fenestrations of Boren) and all of these channels must be obliterated for obstructive atelectasis to occur. Such collateral ventilation does not occur between lobes, unless the interlobar fissures are incomplete (which is the case in ≥50 percent of normal persons).

• #1 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  General anesthesia affects such interactions increasing regional pleural pressure (e.g., dorso-caudal in supine patients), resulting in negative transpulmonary pressure and compressive atelectasis. […] The chest wall can be understood as composed by two functional portions: an elastic portion represented by the rib cage and abdominal wall and a constant weight component exerting a hydrostatic pressure represented by the abdomen. […] Changes in these portions will affect pleural pressure and lung expansion in the perioperative period, in line with the previously discussed equilibration of forces throughout the lung. […] The diaphragm is the primary muscle of lung ventilation and, consequently, significantly contributes to lung expansion and atelectasis development during anesthesia. […] Diaphragm tension reduces the transmission of abdominal pressure to the lungs.

• #1 Lung atelectasis | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/lung-atelectasis?lang=us

  potential causes of resorptive atelectasis include obstructing neoplasms, mucus plugging in asthmatics or critically ill patients and foreign body aspiration. […] passive (relaxation) atelectasis occurs when contact between the parietal and visceral pleura is disrupted with loss of normal negative pressure and the lung relaxes due to natural elastic recoil. […] the three most common specific etiologies of passive atelectasis are pleural effusion, pneumothorax and diaphragmatic abnormality. […] compressive atelectasis occurs as a result of any thoracic space-occupying lesion (e.g. large pneumothorax) compressing the lung and forcing air out of the alveoli. […] cicatrisation atelectasis occurs as a result of scarring or fibrosis that reduces lung expansion. […] common etiologies include granulomatous disease, necrotizing pneumonia and radiation fibrosis.

• #1 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Several factors during general anesthesia could impair surfactant function and contribute to the development of atelectasis: inflammatory response, mechanical ventilation, high oxygen concentration, anesthetics, and pulmonary edema. […] Inflammation with surfactant dysfunction is also present during severe respiratory failure and pneumonia. […] This dysfunction can be mediated by inflammatory cytokines, proteases secreted from immune cells, and increased proteins in alveoli. […] The biological response associated with atelectasis, before and after re-expansion, could further compound with the injurious process.

• #1 Atelectasis: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/296468-overview

  Adhesive atelectasis is caused by a lack of surfactant. The surfactant has phospholipid dipalmitoyl phosphatidylcholine, which prevents lung collapse by reducing the surface tension of the alveoli. […] Scarring of the lung parenchyma leads to cicatrization atelectasis. […] Replacement atelectasis is caused by filling of the entire lobe by a tumor such as bronchoalveolar carcinoma. […] Atelectasis is a common pulmonary complication in patients following thoracic and upper abdominal procedures. General anesthesia and surgical manipulation lead to atelectasis by causing diaphragmatic dysfunction and diminished surfactant activity.

• #1 Lung atelectasis | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/lung-atelectasis?lang=us

  adhesive atelectasis occurs from surfactant deficiency. […] depending on etiology, this deficiency may either be diffuse throughout the lungs or localized. […] gravity dependant atelectasis (dependent atelectasis) occurs in the most dependent portions of the lungs due to the weight of the lungs.

• #1 Atelectasis – EMCrit Project

  https://emcrit.org/ibcc/atelectasis/

  Atelectasis is defined as volume reduction of lung tissue, due to reduced aeration. […] The clinical significance of atelectasis varies widely depending on the cause, configuration, and severity. For example, a small amount of dependent atelectasis is commonly seen, with minimal clinical significance. Alternatively, lobar atelectasis may be the cause of respiratory failure. […] Causes include: Interstitial lung disease (e.g., idiopathic pulmonary fibrosis). […] Round atelectasis generally occurs as a consequence of a highly inflammatory pleural effusion. The effusion initially causes compressive atelectasis of the adjacent lung. Inflammation and adhesions on the visceral pleura subsequently prevent the lung from re-inflating as the effusion resolves. The ultimate result is a small area of trapped lung due to visceral pleural fibrosis.

• #1 Atelectasis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK545316/

  Administration of general anesthesia, use of muscle relaxants, obesity, pregnancy, inadequate pain control, and thoracic or cardiopulmonary procedures increase the risk of developing atelectasis in the perioperative period. […] The incidence of atelectasis in patients undergoing general anesthesia is 90%. […] High FiO2 during induction and maintenance of general anesthesia also contributes to atelectasis via absorption atelectasis. […] FRC is reduced in all patients under general anesthesia and in those in the supine position. […] Inadequate pain control can contribute to the development of atelectasis by inducing shallow breathing or splinting. […] Most atelectasis that appears during general anesthesia leads to transient lung dysfunction that resolves within 24 hours after surgery.

• #1 Atelectasis in Anesthesia: Causes and Management – Radius Anesthesia of New Mexico

  https://radiusnm.com/atelectasis/

  Research has shown that atelectasis can appear in the dependent regions of both lungs within five minutes of induction of anesthesia. […] The majority of atelectasis cases that appear during general anesthesia lead to transient lung dysfunction that quickly resolves itself. However, some patients develop significant perioperative respiratory complications that can lead to increased morbidity and mortality if not treated. […] The use of continuous positive airway pressure and positive end-expiratory pressure (PEEP) help to prevent the development of atelectasis. Other methods that have been shown to decrease incidence involve changing the patients position from supine to upright, encouraging the patient to take deep breaths, chest physiotherapy, and tracheal suctioning. Pharmacologic treatment options include mucolytic agents (acetylcysteine) and recombinant human DNase. As mentioned previously, fiberoptic bronchoscopy also has a role in the management of atelectasis. One study showed that fiberoptic bronchoscopy led to improved lung function and reversal of atelectasis in 76% of cases.

• #1 Atelectasis – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/atelectasis/symptoms-causes/syc-20369684

  A blocked airway can cause atelectasis. This is called obstructive atelectasis. Pressure from outside the lung also can cause atelectasis. This is called nonobstructive atelectasis. […] Possible causes of atelectasis due to pressure from outside the lung include: Injury. Chest trauma, such as from a fall or car accident, can cause you to avoid taking deep breaths due to pain. This can lead to the squeezing of your lungs. […] Factors that make you more likely to get atelectasis include: Any condition that makes it hard to swallow. […] Atelectasis makes it harder for your lungs to get oxygen to the air sacs. […] Your risk of pneumonia continues until the atelectasis goes away. Mucus in a collapsed lung may lead to infection. […] Loss of a lobe or a whole lung, especially in an infant or someone with lung disease, can be life-threatening.

• #1 Pulmonary Atelectasis: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/1001160-overview

  Atelectasis refers to incomplete expansion or collapse of part of the lung. It may include a lung subsegment or the entire lung and is almost always a secondary phenomenon, with no sex or race proclivities; however, it may occur more frequently in younger children than in older children and adolescents. The direct morbidity from atelectasis is transient hypoxemia due to blood flowing through the lung, which does not have normal air flow. The blood does not pick up oxygen from the corresponding alveoli. This shunting results in transient hypoxemia. […] The pathophysiologic mechanisms of atelectasis include: Resorption or obstructive atelectasis due to intrinsic or extrinsic airway obstruction; Passive atelectasis from diaphragmatic dysfunction and hypoventilation; Compressive atelectasis from lung tissue compression and ineffective alveolar expansion from intra or thoracic forces; Adhesive atelectasis due to increased surface tension.

• #1 Atelectasis – Lung and Airway Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/lung-and-airway-disorders/bronchiectasis-and-atelectasis/atelectasis

  The more alveoli that are closed, the less gas exchange occurs. Accordingly, atelectasis can decrease the level of oxygen in the blood. […] Treatment of atelectasis may involve making sure deep breathing occurs, relieving airway blockages, or both. […] Symptoms and complications of atelectasis may require treatment.

• #1 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Reduction or loss of such diaphragmatic tone during anesthesia, thus, affects the net balance of stresses acting on the lungs not only reducing the preferential dependent displacement of the diaphragm but also facilitating the transmission of abdominal pressure to the lungs. […] This results in a cephalad shift of the dependent diaphragm with dependent lung compression and atelectasis, and no change or caudad shift of nondependent regions. […] Increased abdominal pressure as present with pneumoperitoneum, obesity, abdominal compartment syndrome, peritonitis, or abdominal shift of intrathoracic blood produces further imbalance of net stresses on the lung, as it exposes the dorso-caudal lung to higher pleural pressure and susceptibility to atelectasis, with cephalad shift of both diaphragm and intra-abdominal organs.

• #1 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  The concept of critical opening pressure has been introduced as the minimal alveolar pressure required to counteract the regional effect of collapsing forces. […] Accordingly, lung units are expanded when alveolar pressure is higher than the critical opening pressure. […] A parallel concept is that of critical closing pressure, i.e., the alveolar pressure below which open lung units collapse. […] The rationale for the use of PEEP derives from such a concept, ultimately aiming to keep alveolar pressures above critical closing pressures at end-exhalation to prevent lung collapse. […] Local variation in critical opening and closing pressures conditions the regions expanded and kept inflated throughout the breathing cycle at a given PEEP. […] Even normal lungs, when mechanically ventilated without PEEP for many hours, will progressively lose aeration preferentially in dorsal regions.

• #1 Atelectasis | Veterian Key

  https://veteriankey.com/atelectasis/

  Gases trapped distal to a closed airway are reabsorbed into the pulmonary circulation because the partial pressure of gases in end-capillary mixed venous blood is lower than in the alveoli, thus establishing a gradient for reabsorption. […] Absorption atelectasis occurs far more rapidly in patients breathing enriched oxygen mixtures because the nitrogen skeleton is diminished or absent. […] Classically atelectasis is associated with a loss of lung volume, and this is often used as an aid in its radiographic diagnosis. Atelectasis may, however, be associated with edema or infiltration of inflammatory cells into the collapsed alveoli and airways, thus creating a condition of airlessness without volume loss. […] Weakness of respiratory muscles, pain, and centrally mediated respiratory depression can cause inadequate lung expansion and atelectasis.

• #1 Post-Operative Atelectasis – Risk Factors – Management – TeachMeSurgery

  https://teachmesurgery.com/perioperative/cardiorespiratory/atelectasis/

  Atelectasis refers to a partial collapse of the small airways. The majority of post-operative patients will develop some degree of atelectasis, resulting in abnormal alterations in lung function or compromise to the lungs immune defences. […] Atelecrasis like occurs post-operatively from airway collapse is due to a combination of airway compression, alveolar gas resorption intra-operatively, and impairment of surfactant production. […] In atelectasis, the reduced airway expansion and subsequent accumulation of pulmonary secretions will predispose patients to developing pulmonary complications. These include hypoxaemia, reduced lung compliance, pulmonary infections, and acute respiratory failure. […] The degree of lung tissue involved is variable, depending on the underlying cause. Most cases seen are in the post-operative period, typically developing within 24 hours of surgical intervention.

• #1 Atelectasis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK545316/

  Atelectasis is preventable through avoidance of general anesthesia, early mobilization, adequate pain control, and minimizing parenteral opioid administration. […] Changing position from supine to upright increases FRC and decreases atelectasis. […] The mechanism behind these measures is a transient increase in transmural pressure that allows for the reexpansion of collapsed lung segments. […] Fiberoptic bronchoscopy also plays a role in the management of atelectasis.

• #1 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Knowledge of such pathophysiological mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management. […] General anesthesia, mechanical ventilation and surgical interventions produce several biophysical factors promoting lung tissue collapse. […] Three major interrelated collapsing factors influence the balance of forces discussed above and contribute to perioperative atelectasis: increased pleural pressure, low alveolar pressure and surfactant impairment. […] As a result of these factors, continuous or intermittent airway and alveolar closure occur, presumably more commonly the first than the latter. […] Pleural pressure is the pressure within the pleural cavity. It varies regionally across the pleural space depending on anatomical and physiological interactions between the lung parenchyma, chest wall and gravity.

• #2 Atelectasis – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK545316/

  Administration of general anesthesia, use of muscle relaxants, obesity, pregnancy, inadequate pain control, and thoracic or cardiopulmonary procedures increase the risk of developing atelectasis in the perioperative period. […] The incidence of atelectasis in patients undergoing general anesthesia is 90%. […] High FiO2 during induction and maintenance of general anesthesia also contributes to atelectasis via absorption atelectasis. […] FRC is reduced in all patients under general anesthesia and in those in the supine position. […] Inadequate pain control can contribute to the development of atelectasis by inducing shallow breathing or splinting. […] Most atelectasis that appears during general anesthesia leads to transient lung dysfunction that resolves within 24 hours after surgery.

• #2 Atelectasis: Types and pathogenesis in adults – UpToDate

  https://www.uptodate.com/contents/atelectasis-types-and-pathogenesis-in-adults/print

  Atelectasis describes the loss of lung volume due to the collapse of lung tissue. It can be classified according to the pathophysiologic mechanism (eg, compressive atelectasis), the amount of lung involved (eg, lobar, segmental, or subsegmental atelectasis), or the location (ie, specific lobe or segment location). […] The classification of atelectasis according to the pathophysiologic mechanism is reviewed here, as are the mechanisms of each type of atelectasis. […] Atelectasis can be divided pathophysiologically into obstructive and nonobstructive atelectasis. […] Obstructive (ie, resorptive) atelectasis is a consequence of blockage of an airway. Air retained distal to the occlusion is resorbed from nonventilated alveoli, causing the affected regions to become totally gasless and then collapse. The rate at which this occurs depends upon several factors, particularly the amount of collateral ventilation and the composition of inspired gas.

• #2 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  The concept of critical opening pressure has been introduced as the minimal alveolar pressure required to counteract the regional effect of collapsing forces. […] Accordingly, lung units are expanded when alveolar pressure is higher than the critical opening pressure. […] A parallel concept is that of critical closing pressure, i.e., the alveolar pressure below which open lung units collapse. […] The rationale for the use of PEEP derives from such a concept, ultimately aiming to keep alveolar pressures above critical closing pressures at end-exhalation to prevent lung collapse. […] Local variation in critical opening and closing pressures conditions the regions expanded and kept inflated throughout the breathing cycle at a given PEEP. […] Even normal lungs, when mechanically ventilated without PEEP for many hours, will progressively lose aeration preferentially in dorsal regions.

• #2 Lung atelectasis | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/lung-atelectasis?lang=us

  potential causes of resorptive atelectasis include obstructing neoplasms, mucus plugging in asthmatics or critically ill patients and foreign body aspiration. […] passive (relaxation) atelectasis occurs when contact between the parietal and visceral pleura is disrupted with loss of normal negative pressure and the lung relaxes due to natural elastic recoil. […] the three most common specific etiologies of passive atelectasis are pleural effusion, pneumothorax and diaphragmatic abnormality. […] compressive atelectasis occurs as a result of any thoracic space-occupying lesion (e.g. large pneumothorax) compressing the lung and forcing air out of the alveoli. […] cicatrisation atelectasis occurs as a result of scarring or fibrosis that reduces lung expansion. […] common etiologies include granulomatous disease, necrotizing pneumonia and radiation fibrosis.

• #2 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Reduction or loss of such diaphragmatic tone during anesthesia, thus, affects the net balance of stresses acting on the lungs not only reducing the preferential dependent displacement of the diaphragm but also facilitating the transmission of abdominal pressure to the lungs. […] This results in a cephalad shift of the dependent diaphragm with dependent lung compression and atelectasis, and no change or caudad shift of nondependent regions. […] Increased abdominal pressure as present with pneumoperitoneum, obesity, abdominal compartment syndrome, peritonitis, or abdominal shift of intrathoracic blood produces further imbalance of net stresses on the lung, as it exposes the dorso-caudal lung to higher pleural pressure and susceptibility to atelectasis, with cephalad shift of both diaphragm and intra-abdominal organs.

• #2 Passive atelectasis | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/passive-atelectasis-1?lang=us

  Passive atelectasis, also known as relaxation atelectasis is due to elastic recoil of the lung when normal negative pleural pressure is reduced or lost due to a pleural collection such as a pneumothorax or pleural effusion. […] With a loss of the negative intrapleural pressure there is equalization of intrapleural and intra-alveolar pressures and the lung is said to „relax” due to its normal elastic recoil resulting in lung volume loss. […] In the case of diaphragmatic abnormalities, there is a reduction in downward force to fully expand the lungs resulting in passive atelectasis.

• #2 Atelectasis: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/296468-overview

  Adhesive atelectasis is caused by a lack of surfactant. The surfactant has phospholipid dipalmitoyl phosphatidylcholine, which prevents lung collapse by reducing the surface tension of the alveoli. […] Scarring of the lung parenchyma leads to cicatrization atelectasis. […] Replacement atelectasis is caused by filling of the entire lobe by a tumor such as bronchoalveolar carcinoma. […] Atelectasis is a common pulmonary complication in patients following thoracic and upper abdominal procedures. General anesthesia and surgical manipulation lead to atelectasis by causing diaphragmatic dysfunction and diminished surfactant activity.

• #2 Atelectasis | 5-Minute Clinical Consult

  https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/1688658/all/Atelectasis

  Nonobstructive atelectasis: Passive atelectasis (i.e., during a pleural effusion, pneumothorax, or large emphysematous bulla) is due to pleural membrane separation of the visceral and parietal layers. […] Compression atelectasis occurs with space-occupying lesions, cardiomegaly, abscess, or significant lymphadenopathy. The increased chest wall pressure compresses the alveoli. […] Adhesive atelectasis occurs in the setting of acute respiratory distress syndrome (ARDS), radiation, smoke inhalation, posttraumatic lung contusion, or uremia. The underlying surfactant dysfunction causes increased surface tension and alveoli collapse. […] Cicatrization atelectasis is common in granulomatous disease (i.e., sarcoidosis, TB), toxic or radiation exposure, and drug-induced fibrosis (i.e., amiodarone, cyclophosphamide). The scarring and fibrosis reduce lung expansion. […] Replacement atelectasis: occurs when a tumor fills alveoli of a lobe causing complete lobar collapse. […] Rounded atelectasis is a distinct form of atelectasis seen in patients with asbestos exposure.

• #2 Atelectasis – Wikipedia

  https://en.wikipedia.org/wiki/Atelectasis

  This type is defined by blockage of the airway with air trapping and subsequent absorption of air distal to the obstruction. […] This type of atelectasis is due to lack or dysfunction of surfactant, which normally functions to reduce alveolar surface tension. […] This type occurs when the extra-alveolar pressure overcomes the intra-alveolar pressure, which results in collapse of the lung tissue. […] This type of atelectasis occurs when there is loss of contact of the lung to the chest wall. […] This type of atelectasis occurs when alveoli of an entire lobe of the lung are filled by a tumor, typically bronchioloalveolar carcinoma. […] This type occurs when there is contraction of the lung tissue due to the presence of scar tissue.

• #2 Atelectasis | Deranged Physiology

  https://derangedphysiology.com/main/required-reading/respiratory-intensive-care/Chapter-10/atelectasis

  Dependent atelectasis […] Gravity is responsible for the collapse of lung bases in a chronically supine or recumbent person, in the absence of regular vigorous deep breathing exercises. The weight of the lung above pushes on the lung below, producing compression. Under real-world condition, the weight of the massive obese chest wall and distended post-operative abdomen are also contributing to this.

• #2 Round atelectasis in sarcoidosis | Multidisciplinary Respiratory Medicine | Full Text

  https://mrmjournal.biomedcentral.com/articles/10.1186/2049-6958-6-3-180

  Round atelectasis is a benign inflammatory condition most frequently observed in patients with asbestos exposure but it can also result from a variety of chronic pleural diseases like infection. […] The mechanical influence of a prior pleural effusion due to sarcoidosis may be the predominant mechanism underlying the onset of round atelectasis in these patients. […] Round atelectasis may be the result of the mechanical influence of a pleural effusion on the lung with folding of the parenchyma or a primary localized inflammation of the pleura may become progressively fibrotic and contract, leading to folding of the pleura and collapse of the lung. […] Transient pleural effusion or a localized pleural inflammation associated with sarcoidosis may have led to round atelectasis in our patients as the above theories have suggested. […] We conclude that round atelectasis may occur as a result of previous pleural effusion or a primary localized pleural involvement in sarcoidosis. […] Our cases suggest that clinicians should consider sarcoidosis as a potential etiologic factor for round atelectasis.

• #2 Atelectasis in Anesthesia: Causes and Management – Radius Anesthesia of New Mexico

  https://radiusnm.com/atelectasis/

  The term atelectasis originates from the Greek words atelez and ektasiz, meaning imperfect and expansion respectively, and describes an incomplete expansion of lung tissue, resulting from the partial or complete collapse of the small airways and leading to an impaired exchange of CO2 and O2. A study in 1995 estimated that the incidence of atelectasis in patients undergoing general anesthesia is around 90%. This condition typically occurs within 72 hours of general anesthesia and is a common postoperative complication. […] Compression atelectasis is the result of a decreased transmural pressure gradient across the alveolus, leading to alveolar collapse. Resorptive atelectasis occurs when alveolar air gets absorbed distal to an obstructive lesion. The obstruction either partially or completely inhibits ventilation to the area. Over time, all of the air in that segment will be absorbed and, without return of ventilation, the airway will collapse.

• #2 Atelectasis in one lung ventilation: the good, the bad, and the ugly: a narrative review – Bussières – Current Challenges in Thoracic Surgery

  https://ccts.amegroups.org/article/view/68133/html

  The persistence of atelectasis from the perioperative to the postoperative setting can represent the starting point for a deleterious cascade of PPCs. […] The use of a high FiO2 during induction, maintenance of OLV, and emergence is a major cause of anesthesia-induced atelectasis, which is secondary to alveolar gas resorption.

• #2 Pulmonary Atelectasis: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/1001160-overview

  Atelectasis refers to incomplete expansion or collapse of part of the lung. It may include a lung subsegment or the entire lung and is almost always a secondary phenomenon, with no sex or race proclivities; however, it may occur more frequently in younger children than in older children and adolescents. The direct morbidity from atelectasis is transient hypoxemia due to blood flowing through the lung, which does not have normal air flow. The blood does not pick up oxygen from the corresponding alveoli. This shunting results in transient hypoxemia. […] The pathophysiologic mechanisms of atelectasis include: Resorption or obstructive atelectasis due to intrinsic or extrinsic airway obstruction; Passive atelectasis from diaphragmatic dysfunction and hypoventilation; Compressive atelectasis from lung tissue compression and ineffective alveolar expansion from intra or thoracic forces; Adhesive atelectasis due to increased surface tension.

• #2

  https://link.springer.com/article/10.1007/BF03007795

  The pathophysiological basis of pulmonary atelectasis is reviewed and risk factors that enhance lung collapse are discussed. […] Instability of lung alveoli is a consequence of surface tension and regional differences in alveolar size. The inherent tendency of alveoli to collapse is enhanced by the following risk factors; low lung volume, high closing volume, oxygen therapy, a rapid shallow ventilatory pattern, chronic lung disease, smoking, obesity, postoperative pain following abdominal or thoracic surgery, narcotic induced ventilatory depression, and neurological, neuromuscular, muscular and musculoskeletal diseases associated with mechanical impairment of respiratory function. […] The primary goal of perioperative respiratory management is prevention of atelectasis. Appropriate management strategies include physiotherapy and delay of elective surgery if substantial improvement in respiratory status can be achieved by specific treatments such as antibiotics, bronchodilators, steroids, and reduction of tobacco use and caloric intake. In selected cases, elective postoperative controlled ventilation may be indicated.

• #2 Atelectasis pathophysiology – wikidoc

  https://www.wikidoc.org/index.php/Atelectasis_pathophysiology

  Ventilation defect […] Bronchial obstruction leads to resorption of alveolar gas by the blood circulating in the alveolar capillary membrane. […] Alveolar gas reabsorption due to obstruction leads to diminished lung volume and subsequent atelectasis. […] Perfusion defect […] Perfusion of under ventilated lung tissue leads to hypoxemia due to shunt formation. leading to obstruction […] Non obstructive atelectasis occurs due to severe lung scarring caused by necrotizing pneumonias or 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 surfactant can lead to adhesive atelectasis presenting as ARDS.

• #2 Atelectasis – Lung and Airway Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/lung-and-airway-disorders/bronchiectasis-and-atelectasis/atelectasis

  The more alveoli that are closed, the less gas exchange occurs. Accordingly, atelectasis can decrease the level of oxygen in the blood. […] Treatment of atelectasis may involve making sure deep breathing occurs, relieving airway blockages, or both. […] Symptoms and complications of atelectasis may require treatment.

• #2 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Several factors during general anesthesia could impair surfactant function and contribute to the development of atelectasis: inflammatory response, mechanical ventilation, high oxygen concentration, anesthetics, and pulmonary edema. […] Inflammation with surfactant dysfunction is also present during severe respiratory failure and pneumonia. […] This dysfunction can be mediated by inflammatory cytokines, proteases secreted from immune cells, and increased proteins in alveoli. […] The biological response associated with atelectasis, before and after re-expansion, could further compound with the injurious process.

• #2 Post-Operative Atelectasis – Risk Factors – Management – TeachMeSurgery

  https://teachmesurgery.com/perioperative/cardiorespiratory/atelectasis/

  Atelectasis refers to a partial collapse of the small airways. The majority of post-operative patients will develop some degree of atelectasis, resulting in abnormal alterations in lung function or compromise to the lungs immune defences. […] Atelecrasis like occurs post-operatively from airway collapse is due to a combination of airway compression, alveolar gas resorption intra-operatively, and impairment of surfactant production. […] In atelectasis, the reduced airway expansion and subsequent accumulation of pulmonary secretions will predispose patients to developing pulmonary complications. These include hypoxaemia, reduced lung compliance, pulmonary infections, and acute respiratory failure. […] The degree of lung tissue involved is variable, depending on the underlying cause. Most cases seen are in the post-operative period, typically developing within 24 hours of surgical intervention.

• #2 Atelectasis in Anesthesia: Causes and Management – Radius Anesthesia of New Mexico

  https://radiusnm.com/atelectasis/

  Research has shown that atelectasis can appear in the dependent regions of both lungs within five minutes of induction of anesthesia. […] The majority of atelectasis cases that appear during general anesthesia lead to transient lung dysfunction that quickly resolves itself. However, some patients develop significant perioperative respiratory complications that can lead to increased morbidity and mortality if not treated. […] The use of continuous positive airway pressure and positive end-expiratory pressure (PEEP) help to prevent the development of atelectasis. Other methods that have been shown to decrease incidence involve changing the patients position from supine to upright, encouraging the patient to take deep breaths, chest physiotherapy, and tracheal suctioning. Pharmacologic treatment options include mucolytic agents (acetylcysteine) and recombinant human DNase. As mentioned previously, fiberoptic bronchoscopy also has a role in the management of atelectasis. One study showed that fiberoptic bronchoscopy led to improved lung function and reversal of atelectasis in 76% of cases.

• #2 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Knowledge of such pathophysiological mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management. […] General anesthesia, mechanical ventilation and surgical interventions produce several biophysical factors promoting lung tissue collapse. […] Three major interrelated collapsing factors influence the balance of forces discussed above and contribute to perioperative atelectasis: increased pleural pressure, low alveolar pressure and surfactant impairment. […] As a result of these factors, continuous or intermittent airway and alveolar closure occur, presumably more commonly the first than the latter. […] Pleural pressure is the pressure within the pleural cavity. It varies regionally across the pleural space depending on anatomical and physiological interactions between the lung parenchyma, chest wall and gravity.

• #2 Atelectasis – Pulmonary Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/pulmonary-disorders/bronchiectasis-and-atelectasis/atelectasis

  Atelectasis refers to the collapse of lung tissue with loss of volume. […] Major consequences of atelectasis include impaired gas exchange (ie, hypoxia and/or hypercapnia), pneumonia, and respiratory failure in severe cases. […] The most common factors that can cause atelectasis include the following: Intrinsic obstruction of airways (eg, by foreign body, tumor, mucous plug) […] Extrinsic compression of airways (eg, by tumors, lymphadenopathy) […] Compression or collapse of lung parenchyma (eg by large pleural effusion or pneumothorax). […] Thoracic and abdominal surgeries are very common causes because they involve general anesthesia, opioid use (with possible secondary respiratory depression), and often painful respiration. […] Less common causes of atelectasis include surfactant deficiency or dysfunction, lung parenchymal scarring, or tumors.

• #3 Atelectasis in Anesthesia: Causes and Management – Radius Anesthesia of New Mexico

  https://radiusnm.com/atelectasis/

  The term atelectasis originates from the Greek words atelez and ektasiz, meaning imperfect and expansion respectively, and describes an incomplete expansion of lung tissue, resulting from the partial or complete collapse of the small airways and leading to an impaired exchange of CO2 and O2. A study in 1995 estimated that the incidence of atelectasis in patients undergoing general anesthesia is around 90%. This condition typically occurs within 72 hours of general anesthesia and is a common postoperative complication. […] Compression atelectasis is the result of a decreased transmural pressure gradient across the alveolus, leading to alveolar collapse. Resorptive atelectasis occurs when alveolar air gets absorbed distal to an obstructive lesion. The obstruction either partially or completely inhibits ventilation to the area. Over time, all of the air in that segment will be absorbed and, without return of ventilation, the airway will collapse.

• #3 Perioperative Pulmonary Atelectasis – Part I: Biology and Mechanisms

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9869183/

  Knowledge of such pathophysiological mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management. […] General anesthesia, mechanical ventilation and surgical interventions produce several biophysical factors promoting lung tissue collapse. […] Three major interrelated collapsing factors influence the balance of forces discussed above and contribute to perioperative atelectasis: increased pleural pressure, low alveolar pressure and surfactant impairment. […] As a result of these factors, continuous or intermittent airway and alveolar closure occur, presumably more commonly the first than the latter. […] Pleural pressure is the pressure within the pleural cavity. It varies regionally across the pleural space depending on anatomical and physiological interactions between the lung parenchyma, chest wall and gravity.

• #3 Lung atelectasis | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/lung-atelectasis?lang=us

  Atelectasis is a radiopathological sign that can be categorized in many ways. Each approach aims to help identify possible underlying causes together with other accompanying radiological and clinical findings. […] Atelectasis can be subcategorised based on the underlying mechanism, as follows: […] resorptive (obstructive) atelectasis occurs as a result of complete obstruction of an airway. […] no new air can enter the portion of the lung distal to the obstruction, and any air that is already there is eventually absorbed into the pulmonary capillary system, leaving a collapsed section of the affected lung. […] because the visceral and parietal pleura do not separate in resorptive atelectasis, traction is created, and if the loss of volume is considerable, mobile thoracic structures may be pulled toward the side of volume loss („mediastinal shift”).

• #3 Atelectasis pathophysiology – wikidoc

  https://www.wikidoc.org/index.php/Atelectasis_pathophysiology

  Passive atelectasis occurs due to absence of contact between the parietal and visceral pleurae due to fluid (pleural effusion), air (pneumothorax), blood (hemothorax) etc. […] Atelectasis of the upper lobe commonly occurs due to pneumothorax, whereas atelectasis of the middle and lower lobes occurs due to pleural effusion. […] Rounded atelectasis, which presents at a mean age of 60 years, arises due to formation of fibrous bands which adhere the lung to the pleura. […] There is a high association of rounded atelectasis in asbestosis due to the formation of fibrous pleural plaques.

• #3 Lung atelectasis | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/lung-atelectasis?lang=us

  adhesive atelectasis occurs from surfactant deficiency. […] depending on etiology, this deficiency may either be diffuse throughout the lungs or localized. […] gravity dependant atelectasis (dependent atelectasis) occurs in the most dependent portions of the lungs due to the weight of the lungs.

• #3 Bibasilar Atelectasis: What It Is and Treatment

  https://www.verywellhealth.com/understanding-atelectasis-2248927

  If there is an underlying cause of atelectasis, it needs to be treated to prevent further collapse. This may involve surgery and chemotherapy for lung cancer, fluid drainage for pleural effusion, and antibiotics to treat lung infections or complications of cystic fibrosis. […] Cicatrization atelectasis is a form of disease in which severe scarring of the lungs (pulmonary fibrosis) reduces their ability to expand. The outlook is far less favorable because the loss of lung volume is permanent and sometimes progressive.

• #3 Atelectasis in one lung ventilation: the good, the bad, and the ugly: a narrative review – Bussières – Current Challenges in Thoracic Surgery

  https://ccts.amegroups.org/article/view/68133/html

  More than 90% of patients develop a certain degree of atelectasis following induction of general anesthesia. Since peri-operative atelectasis can trigger the installation of PPCs, it should be understood and prevented accordingly. One of the major mechanisms that promote the formation of atelectasis in the anesthetized patient is extrinsic lung compression. […] A second mechanism that can induce atelectasis is the resorption of alveolar gas. In the situation where small airways are occluded, pockets of gas distal to the occlusion will be slowly absorbed by the still perfused but non-ventilated alveoli, creating atelectasis. […] A third mechanism involving the loss of surfactant has been proposed since mechanical ventilation with high TVs in animals can induce abnormalities in the alveolar surfactant. However, this mechanism may not be as contributory as compression and resorption atelectasis in OLV.

• #3 Atelectasis – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/atelectasis/symptoms-causes/syc-20369684

  A blocked airway can cause atelectasis. This is called obstructive atelectasis. Pressure from outside the lung also can cause atelectasis. This is called nonobstructive atelectasis. […] Possible causes of atelectasis due to pressure from outside the lung include: Injury. Chest trauma, such as from a fall or car accident, can cause you to avoid taking deep breaths due to pain. This can lead to the squeezing of your lungs. […] Factors that make you more likely to get atelectasis include: Any condition that makes it hard to swallow. […] Atelectasis makes it harder for your lungs to get oxygen to the air sacs. […] Your risk of pneumonia continues until the atelectasis goes away. Mucus in a collapsed lung may lead to infection. […] Loss of a lobe or a whole lung, especially in an infant or someone with lung disease, can be life-threatening.

• #3 Atelectasis – Pulmonary Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/pulmonary-disorders/bronchiectasis-and-atelectasis/atelectasis

  Atelectasis refers to the collapse of lung tissue with loss of volume. […] Major consequences of atelectasis include impaired gas exchange (ie, hypoxia and/or hypercapnia), pneumonia, and respiratory failure in severe cases. […] The most common factors that can cause atelectasis include the following: Intrinsic obstruction of airways (eg, by foreign body, tumor, mucous plug) […] Extrinsic compression of airways (eg, by tumors, lymphadenopathy) […] Compression or collapse of lung parenchyma (eg by large pleural effusion or pneumothorax). […] Thoracic and abdominal surgeries are very common causes because they involve general anesthesia, opioid use (with possible secondary respiratory depression), and often painful respiration. […] Less common causes of atelectasis include surfactant deficiency or dysfunction, lung parenchymal scarring, or tumors.

• #3 Atelectasis in Anesthesia: Causes and Management – Radius Anesthesia of New Mexico

  https://radiusnm.com/atelectasis/

  Research has shown that atelectasis can appear in the dependent regions of both lungs within five minutes of induction of anesthesia. […] The majority of atelectasis cases that appear during general anesthesia lead to transient lung dysfunction that quickly resolves itself. However, some patients develop significant perioperative respiratory complications that can lead to increased morbidity and mortality if not treated. […] The use of continuous positive airway pressure and positive end-expiratory pressure (PEEP) help to prevent the development of atelectasis. Other methods that have been shown to decrease incidence involve changing the patients position from supine to upright, encouraging the patient to take deep breaths, chest physiotherapy, and tracheal suctioning. Pharmacologic treatment options include mucolytic agents (acetylcysteine) and recombinant human DNase. As mentioned previously, fiberoptic bronchoscopy also has a role in the management of atelectasis. One study showed that fiberoptic bronchoscopy led to improved lung function and reversal of atelectasis in 76% of cases.

• #3 Atelectasis | Veterian Key

  https://veteriankey.com/atelectasis/

  Gases trapped distal to a closed airway are reabsorbed into the pulmonary circulation because the partial pressure of gases in end-capillary mixed venous blood is lower than in the alveoli, thus establishing a gradient for reabsorption. […] Absorption atelectasis occurs far more rapidly in patients breathing enriched oxygen mixtures because the nitrogen skeleton is diminished or absent. […] Classically atelectasis is associated with a loss of lung volume, and this is often used as an aid in its radiographic diagnosis. Atelectasis may, however, be associated with edema or infiltration of inflammatory cells into the collapsed alveoli and airways, thus creating a condition of airlessness without volume loss. […] Weakness of respiratory muscles, pain, and centrally mediated respiratory depression can cause inadequate lung expansion and atelectasis.

• #3 Atelectasis: Types and pathogenesis in adults – UpToDate

  https://www.uptodate.com/contents/atelectasis-types-and-pathogenesis-in-adults/print

  Atelectasis describes the loss of lung volume due to the collapse of lung tissue. It can be classified according to the pathophysiologic mechanism (eg, compressive atelectasis), the amount of lung involved (eg, lobar, segmental, or subsegmental atelectasis), or the location (ie, specific lobe or segment location). […] The classification of atelectasis according to the pathophysiologic mechanism is reviewed here, as are the mechanisms of each type of atelectasis. […] Atelectasis can be divided pathophysiologically into obstructive and nonobstructive atelectasis. […] Obstructive (ie, resorptive) atelectasis is a consequence of blockage of an airway. Air retained distal to the occlusion is resorbed from nonventilated alveoli, causing the affected regions to become totally gasless and then collapse. The rate at which this occurs depends upon several factors, particularly the amount of collateral ventilation and the composition of inspired gas.

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