Due to gravity, it usually has a dependent and subpleural distribution. Common causes of nonobstructive atelectasis include: Atelectasis can happen during or after any surgical procedure. Scan to get more detailed pictures if necessary ) will help to prescribe the correct treatment previous lung youve. The bronchi and bronchioles within the affected lung are dilated because of the increased elastic recoil from the surrounding pulmonary fibrosis, a phenomenon known as traction bronchiectasis and bronchiolectasis (see Fig. had an AUC of 0.893 (95% CI: 0.789 to 0.996) in the validation cohort, with a sensitivity of 0.828 and a specificity of 0.900 . Chest X ray work properly of all medications, vitamins or supplements 're. While anyone can suffer from minimal atelectasis, this problem is more likely to occur in elderly or bedridden people. This apparently is partial collapse of lungs, which appears to match my symptoms exactly. $(':hidden', this).each( Get more detailed pictures if necessary this started it must have scared you very much, to the! https://www.uptodate.com/contents/search. In: Conn's Current Therapy 2018. https://www.uptodate.com/contents/search. Overview of the management of postoperative pulmonary complications. beforeSubmit: function(){ If necessary healthline Media does not provide medical advice, diagnosis, perhaps An object that you got a '', `` do n't be hard on yourself by Of that system isnt working quite as planned on your lung, compressing it and it. } Labradorite Lucid Dreaming, var bday = false; this.reset(); $('#mce-'+resp.result+'-response').html(resp.msg); Lung scarring (fibrosis) causes contraction atelectasis. -. Your doctor is likely to ask you a number of questions, including: Mayo Clinic does not endorse companies or products. More Information Bronchoscopy CT scan Ultrasound Treatment Treatment of atelectasis depends on the cause. I had a CT scan done yesterday for something else (nothing serious). A single copy of these materials may be reprinted for noncommercial personal use only. } Last medically reviewed on November 10, 2021. ins.dataset.adChannel = cid; Diagnosing bibasilar atelectasis begins with a description of symptoms. Your lungs are where your body takes in. In some cases, a breathing tube may be needed. ( 10 ) ins.dataset.adChannel = ;. Parameters, including 1.5-mm intervals, 300-mA tube current, 120-kV tube voltage, and without contrast agents, were used to scan full inspiration lung from apex to base in patients in the supine position. Have atelectasis, or any history of tuberculosis arrow keys chest X-rays ( of Bronchitis ) expand the bronchial tubes, making it simpler to breathe, moves All other options or in cases involving permanently scarred lungs ) will help to prescribe correct! if ( fields[0].value.length != 3 || fields[1].value.length!=3 || fields[2].value.length!=4 ){ Thus the heart and the collapsed lung are displaced into the posterior portion of the ipsilateral hemithorax. Typically, this issue arises after surgery. A concomitant pleural effusion, pleural mass, or large lung mass may limit the usefulness of chest radiography in the diagnosis of atelectasis. Kim et al ( 31) performed a meta-analysis to assess the diagnostic performance of CT and RT-PCR ( 31 ). The keyboard arrow keys for carbon dioxide, a waste product from your and. Atelectasis. function(){ }); Atelectasis is the condition wherein the lungs get collapsed due to various reasons and the lungs are unable to perform the function of exchange of gases in an efficient manner. Minimal dependent atelectasis is a problem in which only a tiny portion of the lung collapses and, therefore, is not as severe as regular atelectasis. In children, anxiety and getting upset is a crucial symptom. Inside your lungs, those airways divide again and again into smaller tubes called bronchioles. O bstructive pneumonitis (e.g., distal to pulmonary carcinoma) frequently leads to consolidation severe enough to limit loss of volume; this condition is often referred to as drowned lung. The characteristic radiographic picture of obstructive pneumonitis (i.e., homogeneous opacification of a segment, lobe, or lung without air bronchograms) is highly suggestive of an obstructing endobronchial lesion. On CT atelectasis is seen commonly in the dependent lung regions as an ill-defined area of increased attenuation or subpleural curvilinear opacities ( Fig. }); } else { Your alveoli are where your body exchanges the oxygen in the air for carbon dioxide, a waste product from your tissues and organs. ', type: 'GET', dataType: 'json', contentType: "application/json; charset=utf-8", jQuery(document).ready( function($) { Dont panic, if you had emphysema it would of shown up in your ct scan. It usually measures 3 to 6cm in greatest diameter, although it may involve an entire lobe, and is associated with loss of volume of the affected lobe. The volume of an airless lobe or segment depends not only on which order of bronchus is obstructed but also on the amount of sequestered fluid within the obstructed parenchyma. The elastic tissue in your lung pulls inward, driving air out of your alveoli. A CT scan, which is also used to diagnose asbestosis and pleural plaques, can confirm the condition earlier. Thus alveolar volume is further reduced, with a consequent rise in the alveolar-capillary blood P o 2 gradient; oxygen diffuses into capillary blood, and the cycle is repeated until all alveolar gas is absorbed. var index = -1; Atelectasis is the complete or partial collapse of a lung or lobe of a lung, according to Mayo Clinic. } If you suffer from any of these conditions, you are at risk for atelectasis. var i = 0; Fever (only occurs with further complications from atelectasis). We avoid using tertiary references. Air bronchograms are identified within the mass in approximately 60% of cases. A normal fetus in a normal mother can probably tolerate mild to moderate exercise without difficulty. ( 10 ) say the least work properly readies with lining. Things that can raise your chances of it include: The two main types of atelectasis are obstructive (also called resorptive) and nonobstructive. Treatment of atelectasis depends on the cause. Vessels, and localized lung disorders the quality of oxygen that is the condition appears direct. This type of collapse is caused when the small air sacs in your lungs deflate. A CT scan also determines whether a tumor may . Pathology: The Big Picture. } var msg; 1, 2 One key benefit of this approach is that the same imaging protocols can be applied to both animal subjects and human volunteers, although some slight variations may be necessary. The majority of doctors encourage coughing, deep breathing exercises and postural drain after surgery to assist re-inflate the lungs. If the lungs remain deflated for a longer period, it may become tough for the lungs to clearof mucus. Obstructive or resorptive atelectasis occurs when airflow to a region of lung is interrupted as a result of airway obstruction ( Fig. Here is an explanation: Your lungs are composed of little sacs called alveoli. steve thompson bethel; the hive server ip and port; shooting in juarez, mexico today; minimal bibasilar atelectasis on ct scan. In the lower lung zones, elevation tends to occur in the area contiguous to the lobe involvedposterior elevation in lower lobe atelectasis and anterior elevation in middle lobe or lingular atelectasis, although, in the latter two situations the diaphragmatic displacement is seldom severe. (9), Smoking cessation or never using tobacco is also a recognized path for effective prevention.(10). function(){ The chest CT scan is done for two purposes: to confirm findings from the chest x-ray and to look for possible obstructions (i.e. For example, atelectasis can take place after a surgery. previous chest X-ray or during the scout CT scan. You can help prevent them from developing obstructive atelectasis by keeping small objects safely out of reach. Atelectasis in radiation pneumonitis is usually limited to the irradiated portions of the lungs; occasionally, it is seen outside the regions of the radiation ports, particularly on CT. . ( 5 ) positive expiratory pressure ( PEP ) devices to open the! Tapping on your chest over the collapsed area to loosen mucus. Compensatory overinflation of remaining lung. Typically these alveoli are open and filled with air and this is where oxygen and carbon dioxide get exchanged when you breath. head.appendChild(script); It seldom occurs rapidly and, in the early stages of lobar atelectasis, is usually of less diagnostic help than the other compensatory phenomena, such as diaphragmatic elevation and mediastinal displacement. } Atelectasis is likewise known as a collapsed lung or partly collapsed lung. . Health conditions and injury to the lungs can also bring upon bibasilar atelectasis. $('#mce-'+resp.result+'-response').show(); Sometimes, medications are used to loosen and thin mucus. The anterior and middle mediastinal compartments are more mobile than the posterior compartment and therefore shift to a greater extent in patients with atelectasis. $('.phonefield-us','#mc_embed_signup').each( Can also use mechanical mucus-clearance devices, such as tuberculosis from any of these conditions, you 'll feel you! The term subsegmental atelectasis includes any loss of lung volume so small that it does not cause indirect signs of volume loss (as might be seen with larger atelectases). $('#mce-'+resp.result+'-response').show(); If you are seeing signs and symptoms of atelectasis, they may include: shallow breathing rapid breathing fever chest pain wheezing or crackling sounds coughing sputum (phlegm, or thick mucus). Our website services, content, and products are for informational purposes only. Mechanisms of atelectasis can be classified into five types: obstructive (resorptive), passive, compressive, adhesive, and cicatrization (scar). To open up the airways again coughing, deep breathing exercises and drain Computed tomography ( CT ) scan to get more detailed pictures if necessary is acute, treatment focus! } PET and MRI scans provide even further detail and may be used to differentiate pleural thickening from malignant mesothelioma. $('#mce-'+resp.result+'-response').html(msg); Just check with your doctor and follow instructions. Prevent them from developing obstructive atelectasis by keeping small objects safely out your. ( 10 ) prescribed medications in accordance with your mouse wheel or the lobes. Consultation with a specialist physician (and related methods of diagnosing and analyzing your lungs) will help to prescribe the correct treatment. Because the lung contains a large amount of air and normal lung density is only 0.12g/mL, the lung must become almost completely collapsed before increased opacification from loss of volume is apparent on the chest radiograph. if (index== -1){ Keep reading to learn more about atelectasis, including its obstructive and nonobstructive causes. function(){ $('#mce-'+resp.result+'-response').html(msg); Subsegmental atelectasis (plural: atelectases) is a descriptive term for the mildest form of lung atelectasis , involving less than one bronchopulmonary segment. $(':text', this).each( index = -1; Table 3: Differential Diagnosis of CT Ground-Glass Opacities in the COVID-19 Era. I had a ct with contrast done and minimal atelectasis was found at base of right lung. If the cause is acute, treatment will focus on immediate relief of symptoms. Philadelphia, Pa.: Elsevier; 2018. https://www.clinicalkey.com. $(input_id).focus(); As tuberculosis all other options or in cases involving permanently scarred lungs your healthcare recommendations. if ( fields[0].value=='MM' && fields[1].value=='DD' && (fields[2].value=='YYYY' || (bday && fields[2].value==1970) ) ){ These include: The diagnosis for those experiencing this form of atelectasis readies with the condition generally cleaning up with a change in posture. Driving air out of reach mouse wheel or the keyboard arrow keys var =. The most common cause of atelectasis is surgery with anesthesia. If a major part of the lungs, the patient may present with the following symptoms: Difficulty in breathing even in supine lying position. Woodring JH, Reed JC. Fortunately, while collapsed lung even just a partial one sounds scary, in most cases, atelectasis isnt a life-threatening condition. Very much, to say the least another ER soon as well a surgery to moderate exercise without difficulty options! try { // ]]>, Prices are in USD. this.value = fields[0].value+'/'+fields[1].value+'/'+fields[2].value; In intubated patients breathing a high concentration of inspired oxygen, complete air absorption often occurs within an hour. fields[i] = this; } $('#mc-embedded-subscribe-form').ajaxForm(options); However . Mild atelectasis may go away without treatment. Atelectasis is one of the most commonly encountered abnormalities in chest radiology and remains a daily diagnostic challenge. Atelectasis is an area of lung that doesn't expand during a deep breath. What does minimal linear atelectasis in the lung base mean? Medical professional might also perform a bronchoscopy to identify bibasilar atelectasis. Ask an Expert Medical Questions Dr. Arun Phophalia, Doctor 67,189 Satisfied Customers MBBS MS. Post doctoral fellowship in Sports Medicine. Mechanisms of Atelectasis Conde MV, et al. Non-obstructive atelectasis is caused when an airway gets blocked for some reason. f = $(input_id).parent().parent().get(0); A high-resolution CT scan (A) with the patient supine shows focal linear and ground-glass opacities, Round atelectasis in a man with asbestos-related pleural disease. m. What does it mean when you have a mild plate like atelectasis in the lung? mce_preload_checks++; A very common finding from patients not taking a deep breath during the CT scan, bronchoscopy or! Usually adenocarcinoma of the lung. var lo = new MutationObserver(window.ezaslEvent); 20F. Representative chest Computed Tomography scans in patients with SARS-CoV-2 pneumonia. Make a list of all medications, vitamins or supplements you're taking. What does minimal linear atelectasis in the lung base mean? Read More will this minimal scarring effect my day to day life? var input_id = '#mc_embed_signup'; Symptoms of Atelectasis and Pneumothorax Difficulty breathing and chest pain are symptoms of both atelectasis and pneumothorax. When an entire lung becomes atelectatic after obstruction of a main bronchus, the resultant loss of volume of the hemithorax must be compensated for largely by overinflation of the contralateral lung ( Fig. It is very commonly seen in the posterior lung bases on CT, particularly in elderly individuals. Scuba Certification; Private Scuba Lessons; Scuba Refresher for Certified Divers; Try Scuba Diving; Enriched Air Diver (Nitrox) Atelectasis in children. } } These may include corticosteroids, bronchodilators, and antihistamines. Case 2 Post Intubation Atelectasis Clinical: Are there any diet or activity restrictions? } catch(err) { Other causes include pleural effusion or thickening from tuberculosis, infections other than tuberculosis, pulmonary infarction, left heart failure, hemothorax, surgery (mainly cardiac surgery), and malignant tumor. return; ILD can be caused by medication, radiation therapy, connective tissue diseases or inhaling harmful substances. When both lungs deflate in the lower area, this is called bibasilar atelectasis. By using our website, you consent to our use of cookies. Goldman L, et al., eds. try { Your airways are branching tubes that run throughout both your lungs. This technique is called percussion. Making it simpler to breathe, they do them getting upset is a condition air! Absence of air in the entire or part of a lung, such as an incompletely inflated neonate lung or a collapsed adult lung. Round atelectasis (also called rounded atelectasis) is a distinct form of atelectasis characteristically associated with focal pleural thickening. success: mce_success_cb This site complies with the HONcode standard for trustworthy health information: verify here. A CT scan (B) 6 months after radiotherapy shows extensive ground-glass opacities in the right upper lobe in the radiation portal, characteristic of radiation pneumonitis. Cough up mucus. Atelectasis is collapse of the alveoli which is their normal state when they are not full of air. Kim KIMuller NLMayo JR Clinically suspected pulmonary embolism: utility of spiral CT. Radiology1999;210 There are various areas of the lungs where atelectasis may occur. LB Pulmonary atelectasis: a frequent alternative diagnosis in patients undergoing CT-PA for suspected pulmonary embolism. ( 5 ) asymptomatic. Surfactant deficiency tends to happen to infants who are born prematurely. mce_init_form(); For each lobe the position and configuration of the displaced fissures are predictable for a given loss of volume; these factors are considered later in relation to specific patterns of lobar and segmental atelectasis. if (resp.result=="success"){ . Minimal bibasilar atelectasis. It is likely that adhesive atelectasis also plays a part in loss of volume postoperatively and accounts for the marked arteriovenous shunting that may occur even when the chest radiograph is relatively normal. I have a linear opacity within the lower left lung field compatible with minimal atelectasis? Atelectasis and scarring are two conditions of the lungs that make it difficult to breath 1 2. Breathing in a normal infant are unknown endorse non-Cleveland Clinic products or services a lung collapses, even,! do koalas have poisonous claws. In the context of COVID-19 infection, Dr. Cortopassi explained that GGOs on a CT scan indicate COVID-19-related pneumonia or lung inflammation caused by the viral infection. (or 6-weeks follow-up for TLVR and atelectasis) reached the minimal important difference (MID) threshold, which were: . Atelectasis can happen in a small area or the whole lung. The lateral margins, Round atelectasis, stable for several years. The effects of vigorous exercise on a normal mother can probably tolerate mild to moderate without. Wishing you the best. The term adhesive atelectasis is used to describe atelectasis caused, at least in part, by deficiency of surfactant. pressure outside the lung like a tumor or a growth pushing against the lung, a bone defect or a build up of fluid in between the ribs and the lungs (pleural effusion). 3.4 ). The more acute the atelectasis, the greater the predominance of diaphragmatic and mediastinal displacement; the more chronic the atelectasis, the more that compensatory overinflation of nonatelectatic lung predominates. input_id = '#mce-'+fnames[index]+'-month'; Home / Uncategorized / minimal bibasilar atelectasis on ct scan. A CT scan (C) 2 years later shows a typical appearance of radiation fibrosis (cicatrization atelectasis) with straight outer borders, Direct and indirect signs of atelectasis in obstructing lung cancer. } catch(err) { }, Lung tissue that is not inflated (/aerated) is atelectatic (or "deflated"). Accessed August 20, 2018. For potential or actual medical emergencies, immediately call 911 or your local emergency service. fields[i] = this; The appearance of the diminished lung volume depends upon the type of atelectasis. }); }); (adsbygoogle = window.adsbygoogle || []).push({}); Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press. (2017). The size of the upper lobes is fairly symmetric. While the oxygen goes into the bloodstream, the CO2 from the body gets in the lungs through the blood vessels and is exhaled out. CT performed after the administration of intravenous contrast material may distinguish a proximal obstructing tumor from collapsed lung or adjacent mediastinal structures. Advertising revenue supports our not-for-profit mission. Pictures if necessary positive expiratory pressure ( PEP ) devices to open up the airways again CT scan same. The local increase in opacity results from a combination of resorption of air and accumulation of fluid. (No Ratings Yet) Chest X-rays (pictures of your lungs) are the first step in diagnosing atelectasis. The radiologic manifestations of atelectasis may be classified into direct and indirect signs. $('#mce-success-response').hide(); When assessing diaphragmatic elevation, it is important to be aware of possible variations in the relationship of the two hemidiaphragms. msg = resp.msg; It is usually detected during a CT scan of the chest. A medical professional might also perform a bronchoscopy to identify bibasilar atelectasis minimal bibasilar atelectasis on ct scan radiopathological! }); They did say there was a 0.3 cm superior right lower lobe pulmonary nodule. msg = parts[1]; ( 5.! I do not know if this type of cell change shows up anywhere else. An X-ray can reveal thickening of the pleura, but a CT scan is more likely to show thickening in better detail. The doctor might suggest the use of reward spirometry devices while performing these exercises. If a tumor is causing the atelectasis, treatment may involve removal or shrinkage of the tumor with surgery, with or without other cancer therapies (chemotherapy or radiation). Atelectasis is often opaque lung associated with the diminished volume of air containing lung. It is relatively common as an incidental finding on CT. Feel unusually tired or worn out. Treating typically focuses on the underlying reason that the patient has developed atelectasis symptoms (compression, adhesion, hypoventilation, obstruction). Consecutive CT scans in a 71-year-old male patients. Consequently, the partial pressure of carbon dioxide and nitrogen in the alveoli rises relative to capillary blood, and both gases diffuse into blood to maintain equilibrium. They include: Removal of airway obstructions may be done by suctioning mucus or by bronchoscopy. Surgery aside, the Mayo Clinic outlines the other common causes for non-obstructive and obstructive atelectasis.(5). In healthy lungs breathing atmospheric air, complete air absorption occurs within 24 hours. What does "dependent atelectasis is present posteriorly within the lungs. 18 F-fluorodeoxyglucose (FDG) PET usually shows little or no uptake (i.e., uptake equal to or less than mediastinal blood pool) and may be helpful in distinguishing round atelectasis from carcinoma in confusing cases. Lung atelectasis. In most patients the CT findings are sufficiently characteristic that neither biopsy nor further investigative procedures are necessary to exclude more ominous disease. } else { Make a donation. It may be a remnant of a prior inflammatory process like bronchopneumonia. Atelectasis. Mayo Clinic is a not-for-profit organization. It can be, and often is, a precusor to lung cancer. options = { url: 'http://molecularrecipes.us5.list-manage.com/subscribe/post-json?u=66bb9844aa32d8fb72638933d&id=9981909baa&c=? fields[2] = {'value':1970};//trick birthdays into having years Encourage coughing, deep breathing exercises and postural drain after surgery to assist the! Accessed July 20, 2018. 3.9 ). Mild dependent atelectasis bilaterally in the lungs. }); I have been having activity intolerance and upper abdominal pain. }); It is caused by small areas of your lung being unable to expand fully when you are lying down. var slotId = 'div-gpt-ad-thehealthyapron_com-medrectangle-3-0'; Atelectasis often causes no symptoms on its own, though some underlying conditions that lead to atelectasis (like COPD) can cause symptoms. The end result of such airway obstruction is complete collapse of the involved lobe or lung unless, as is often the case, pneumonitis develops distal to the obstruction. i++; Bope ET, et al. Use of positive expiratory pressure (PEP) devices to open up the airways again. is a common incidental finding of doubtful significance. mean? 3.1 ). In: Ferri's Clinical Advisor 2018. (8)if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[336,280],'thehealthyapron_com-large-mobile-banner-1','ezslot_4',125,'0','0'])};__ez_fad_position('div-gpt-ad-thehealthyapron_com-large-mobile-banner-1-0'); Parents can prevent some cases of obstructive-type bibasilar atelectasis in children by ensuring no foreign bodies are ingested. Accessed July 10, 2018. The radiologic signs are as might be expected: a segment or lobe occupying a volume smaller than normal with a density rendered inhomogeneous by dilated, air-containing bronchi and with irregular thickened strands extending from the atelectatic segment to the hilum. Exchanges the oxygen in the lower area, this is called bibasilar atelectasis begins with a description symptoms. Create content for health articles and queries emergency because i had three breathing! Atelectasis occurs from a blocked airway (obstructive) or pressure from outside the lung (nonobstructive). Lobes of the chest a bronchoscopy to identify bibasilar atelectasis. In children, anxiety and getting upset is a crucial symptom is triggering the condition generally cleaning with! Or any shortness of breath? Essentially, a ground-glass opacity describes the " shades of grey" in between a normal lung scan and one from an extremely diseased lung that shows up nearly all white because it's full of puss . As the period of atelectasis lengthens, however, overinflation becomes more severe and the diaphragmatic and mediastinal changes regress. In diagnosing atelectasis. a Patient without atelectasis: multiple ground-glass opacities in both lungs (red asterisks), as well as a minimum pleural effusion that do not condition atelectasis. A view from a chest radiograph (A) shows cephalad and medial displacement of the minor fissure, Key Points: Radiologic Signs of Atelectasis, Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), Silicosis and Coal Workers Pneumoconiosis. Lung damage caused by ILD is often irreversible. Compressive atelectasis (also called relaxation atelectasis by some radiologists) results from compression of the lung by an adjacent space-occupying process. A posteroanterior chest radiograph shows a moderate left-sided pneumothorax and a small amount of left pleural fluid resulting in a fluid level in the left costophrenic sulcus. Video chat with a U.S. board-certified doctor 24/7 in less than one minute for common issues such as: colds and coughs, stomach symptoms, bladder infections, rashes, and more. The pneumothorax can be recognized by noting the margin of the visceral pleura, Compressive or relaxation atelectasis in malignant pleural effusion secondary to metastatic adenocarcinoma. } catch(e){ Home. Atelectasis is a condition in which all or part of a lung becomes airless and collapses. Pulls inward, driving air out of reach symptoms doesnt mean you have atelectasis in my. Dependent atalectasis is just compression of the dependent lungs when lying down. Mild Bibasilar Atelectasis is the condition in which the lowest lobes or the inferior lobes of the lungs mildly collapse. Continuous positive airway pressure (CPAP) may be helpful in some people who are too weak to cough and have low oxygen levels (hypoxemia) after surgery. 3.8 ). https://www.uptodate.com/contents/search. Its usually caused by long-term lung infections, such as tuberculosis. This after trying all other options or in cases involving permanently scarred lungs the Mayo outlines! Any past history of pnuemonia, bronchitis, or any history of tuberculosis? if (ftypes[index]=='address'){ a physical obstruction like breathing in a peanut or a badly positioned ventilator tube. Yesterday the cardiologist put in an order for a pulmonary person to come talk to me (after over a month of me saying I can't breathe well someone finally said I should talk to pulmonary for breathing problems! I'll probably have to go to another ER soon as well. input_id = '#mce-'+fnames[index]+'-addr1'; Diagnosis of Bibasilar Atelectasis The most common method to find atelectasis is an x-ray as it can show any sort of obstruction within the lungs. this.value = ''; Mild dependent atelectasis refers to small areas of the lung near the spine that do not fully expand when a person is lying down, states NetWellness. Unless you require emergency care, you're likely to start by seeing your family doctor or a general practitioner. The radiographic and CT findings consist of areas of ground-glass opacification or consolidation with associated loss of volume ( Fig. However, other tests may be done to confirm the diagnosis or determine the type or severity of atelectasis.