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At least 379 records · Page 21Linked to original sources
PubMed1976

Phasic reflux of pulmonary blood flow in atelectasis: influence of systemic PO2.

In 16 dogs ventilated with 100% O2, control blood flow to the left lung was 35 +/- 2% of aortic flow. When left lung atelectasis was induced, left pulmonary artery flow fell to 19 +/- 2% of aortic flow. A large retrograde component of flow developed in this pulmonary artery, suggesting that blood flows into the pulmonary arteries of both lungs during systole, but flows back out of the collapsed lung and into the uncollapsed lung during diastole. Systemic PaO2 remained above 78 mmHg. Subsequently, when the ventilation of the right lung was changed from oxygen to room air, systemic PaO2 fell to 64 +/- 3 mmHg and atelectatic left lung flow rose from 19 +/- 2% to 28 +/- 2% f aortic flow. This was associated with a reduction in reflux from the atelectatic lung. These results suggest that the attenuation of flow to an atelectatic lung is more pronounced if systemic normoxemia is maintained by adequate oxygenation of the normal lung.

Animals↗
PubMed1979

Sublobar atelectasis and regional pulmonary blood flow.

We studied the effects of sublobar atelectasis on regional blood flow in anesthetized paralyzed pigs. Following the washout of nitrogen from the lung with oxygen, a sublobar airway was obstructed and a peripheral segment of lung allowed to collapse. Blood flow to the atelectatic region fell from a control of 140.0 +/- 20.5 to 16.6 +/- 2.9 ml/(min . g). Basilar regions that became atelectatic spontaneously during the course of the studies had similar decreases in blood flow. Inflation of the surrounding lung by the application of positive end-expiratory pressure failed to increase blood flow and vascular conductance within the atelectatic regions. These results indicate that mechanical and hypoxic effects on vessels perfusing sublobar atelectatic regions limit the effects of interdependence from the surrounding lung. Furthermore, with inflation of the surrounding lung, increases in pulmonary shunting of blood are small.

Animals↗
PubMed1988

Lung volume recruitment during high-frequency oscillation in atelectasis-prone rabbits.

In diffuse lung injury, optimal oxygenation occurs with high-frequency oscillatory ventilation (HFO-A, where A is active expiratory phase) when sustained inflations (SI) are applied periodically to recruit lung volume. Theoretically pulsed pressures may be safer and more effective than static pressures for reexpanding alveoli. We compared the increases in lung volume and arterial PO2 (PaO2) induced by 30-s increases in mean airway pressure in six New Zealand White rabbits made atelectasis prone by saline lavage plus 1 h of conventional ventilation. Pulsatile SI's (HFO-A left on during increase in mean pressure) of delta PSI = 5, 10, and 15 cmH2O and static SI's (HFO-A off during SI) of delta PSI = 5, 10, 15, and 20 cmH2O were delivered in random order. Lungs were ventilated at 15 Hz, inspired fractional concentration of O2 = 1.0, and mean airway pressure 15-20 cmH2O between test periods and deflated to functional residual capacity before each SI to standardize volume history. With both maneuvers, increases in lung volume and PaO2 induced by SI's were proportional to the magnitude of the SI (P less than 0.001) in all cases. Pulsatile SI's consistently increased lung volume and PaO2 more than static SI's having the same delta PSI (P less than 0.005) such that any given target PaO2 or change in volume (delta V) was achieved at 5 cmH2O less mean pressure with the pulsatile maneuver. Respiratory system compliance increased after both types of SI. Oxygenation and lung volume changes at 5 min were related with r = 0.58 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Clapping or percussion causes atelectasis in dogs and influences gas exchange.

We examined the effects of 10 min of lower lateral chest wall percussion with a mechanical percussor or hand clapping in groups of anesthetized, paralyzed, and ventilated supine dogs. Mechanical percussion was applied at 10-16 Hz and caused an esophageal pressure swing (delta Pes) of 10-17 cmH2O. Hand clapping was applied at 4-7 Hz and caused a delta Pes of 6-17 cmH2O. At necropsy there were large reddened areas on the lateral surface of the underlying lung as well as smaller reddened areas on the hilar surfaces of both lungs and on the lateral surface of the opposite lung. These reddened regions were demonstrated to be atelectatic by postmortem lung inflation (which caused the reddened areas to disappear) and by microscopic examination. Despite the atelectasis, gas exchange improved toward the end of the percussion or clapping period. In four dogs that were ventilated for an additional 20 min after percussion, there was a tendency for gas exchange initially to worsen and then to gradually improve.

Animals↗
PubMed1995

Effect of anemia on intrapulmonary shunt during atelectasis in rabbits.

To elucidate the effects of anemia on intrapulmonary shunt, we studied a model of left lung atelectasis in anesthetized rabbits. In 10 rabbits, isovolemic anemia was produced by sequential hemodilution. Seven control rabbits were followed over time, without hemodilution. Intrapulmonary shunt (Qs/QT) was measured by using blood gas analysis and by quantitation of the percentage of blood flow to the collapsed left lung (QLl/QT) using fluorescent microspheres. In control rabbits, Qs/QT and QLl/QT decreased over time, whereas arterial PO2 increased. In hemodiluted rabbits, there was a trend toward increased Qs/QT and QLl/QT. There were significant differences in the behavior of Qs/QT, QLl/QT, and arterial PO2 between control and hemodiluted rabbits. Hemodynamic parameters, including cardiac output and pulmonary artery pressure, were not different between groups. In a third group of rabbits with pharmacologically induced acidosis but no hemodilution, Qs/QT and QLl/QT decreased over time, and arterial PO2 increased. We conclude that acute isovolemic anemia has a deleterious effect on pulmonary gas exchange, possibly through attenuation of hypoxic pulmonary vasoconstriction.

Anemia↗
PubMed2005

[Lung rounded atelectasis. A benign lesion due to asbestos].

BACKGROUND AND OBJECTIVE: Rounded atelectasis (RA) is an unusual form of pulmonary lesion often confounded with pulmonary neoplasia. We studied the main diagnostic and evolutive characteristics of a series of patients diagnosed with RA. PATIENTS AND METHOD: Twenty patients diagnosed of RA in a tertiary hospital in Catalonia were included in the study. The diagnostic criterion of RA was strictly based on thoracic CT. Clinical data and pulmonary function tests were also evaluated. Four teen patients underwent a long term follow-up. RESULTS: Asbestos was the cause of RA in 13 cases (65%); 7 had previously had homolateral pleural effusion; 5 pulmonary tuberculosis and in 1 case RA appeared at the lung biopsy site. The most frequent localization was inferior lobes and left side (70%). Eighteen patients had a ventilatory disorder: 10 restrictive, 6 mixed and 2 obstructive. In no case, RA evolved to malignancy. CONCLUSIONS: RA is a benign lesion mainly due to asbestos showing well-defined morphological characteristics.

Adult↗
PubMed1987

Endobronchial eosinophilic granuloma: a rare cause of total lung atelectasis.

A 12-yr-old male presented with left lung atelectasis secondary to a mainstem endobronchial mass. At thoracotomy, a left mainstem bronchial sleeve resection successfully extirpated what later proved to be an eosinophilic granuloma. This is the first case report, to our knowledge, of endobronchial eosinophilic granuloma.

Bronchi↗
PubMed1981

The effect of mechanical vibration physiotherapy on arterial oxygenation in acutely ill patients with atelectasis or pneumonia.

The effect of mechanical chest vibration on arterial blood gases was studied in 10 patients requiring oxygen therapy who had acute lung disease and an abnormal chest roentgenogram. Eight patients were using mechanical ventilators. For the duration of the study, patients were seated or in a high semi-Fowlers position. No other pharmacologic or physical therapy was given during the study period, nor was there any change in the fraction of inspired oxygen or the respirator settings. The patients ranged from 23 to 89 yr of age. After control blood gas measurements were taken, each patient received 30 min of mechanical vibration to the thorax followed immediately by tracheal suction. Blood gases were re-examined 30 min and 1 h after completion of the physiotherapy. Results showed a significant increase in PO2 at 30 min and 1 h after completion of mechanical chest vibration with no change in PCO2 or pH. This study demonstrated that external mechanical vibration of the chest is a useful therapeutic modality in the management of hypoxemia in patients with atelectasis or pneumonia. This was reflected by the increase in PO2 with no change in alveolar ventilation. We presume the better matching of ventilation to perfusion accounted for our results.

Adult↗
PubMed1982

Round atelectasis: another pulmonary pseudotumor.

Round atelectasis is a relatively rare form of collapse, associated with pleural thickening, pleural effusions, or pleural plaques. The mass is always in a subpleural location and has a characteristic comet-tail-shaped structure. Recognition of this entity can avert more invasive procedures.

Aged↗
PubMed2003

Atelectasis causes vascular leak and lethal right ventricular failure in uninjured rat lungs.

During mechanical ventilation, lung recruitment attenuates injury caused by high VT, improves oxygenation, and may optimize pulmonary vascular resistance (PVR). We hypothesized that ventilation without recruitment would induce injury in otherwise healthy lungs. Anesthetized rats were ventilated with conventional mechanical ventilation (VT 8 ml/kg; respiratory frequency 40 per minute) and 21% inspired oxygen, with or without a recruitment strategy consisting of recruitment maneuvers plus positive end-expiratory pressure, in the presence or absence of a laparotomy. Additional experiments examined the impact of atelectasis on right ventricular function using echocardiography, as well as functional residual capacity and PVR. Lack of recruitment resulted in reduced overall survival (59% nonrecruited vs. 100% recruited, p < 0.05), increased microvascular leak, greater impairment of oxygenation and lung compliance, increased PVR, and elevated plasma lactate. Echocardiography demonstrated that right ventricular dysfunction occurred in the absence of recruitment. Finally, samples from nonrecruited lungs demonstrated ultrastructural evidence of microvascular endothelial disruption. Although such effects clearly do not occur with comparable magnitude in the clinical context, the current data suggest novel mechanisms (microvascular leak, right ventricular dysfunction) whereby derecruitment may contribute to development of lung injury and adverse systemic outcome.

Animals↗
PubMed1979

Changes in sedimentation of surfactant in ventilated excised rat lungs. Physical alterations in surfactant associated with the development and reversal of atelectasis.

We ventilated excised rat lungs at a constant tidal volume (CTV); they developed areas of atelectasis which could be reversed by a large inflation (CTV + I) or prevented by the addition of positive end-expiratory pressure to the CTV. To explore the possibility that these modes of ventilation led to changes in surfactant, we lavaged the lungs and centrifuged the returns at 500 g; we measured the amount of disaturated phosphatidylcholine (DSPC) in the resultant pellet and supernatant fluid as a marker for surfactant. We found 16.9+/-1.5 (mean+/-SE), 38.0+/-2.4, 18.3+/-1.6, and 21.7+/-2.3% of the total lavage DSPC, in the pellet from freshly excised, CTV, CTV + I, and positive end-expiratory pressure to the CTV lungs, respectively. The total amount of lavage DSPC was the same in all groups. The ultrastructure of acellular material pelleted by sequential centrifugation of lavage returns at 500, 1,000, and 60,000 g was examined. We found mostly tubular myelin in the 500-g and 1,000-g pellets, but no tubular myelin in the 60,000-g pellet. Air inflation pressure-volume measurements from the degassed state revealed that the opening pressure and recoil pressures up to 75% of total lung capacity were significantly higher in the CTV than in the CTV + I lungs. There were no differences between these groups in air deflation or in saline inflation and deflation pressure-volume measurements. Our findings suggest that CTV leads to increases in the tubular myelin form of surfactant and that this leads to increased surface tension in alveoli which results in alveolar collapse.

Animals↗
PubMed2000

Airway burns and atelectasis in an adolescent following aspiration of molten wax.

Scald injuries caused by hot liquids are not a frequently reported cause of pediatric respiratory and alimentary tract burns. Aspiration of molten wax with subsequent pharyngeal or laryngeal burns has not been described at all, to the best of our knowledge. A case of an adolescent who presented with airway burns and atelectasis subsequent to aspiration of molten wax is herein described and discussed.

Bronchi↗
PubMed1997

Middle ear gas composition in pathologic conditions: mass spectrometry in otitis media with effusion and atelectasis.

It is generally assumed that the gas enclosed in the middle ear and mastoid air cell system is subject to continuous absorption, and that partial pressures for oxygen and carbon dioxide equal those of "mixed venous blood." We previously determined the concentrations in 10 adults with healthy ears by means of mass spectrometry. The results showed that the value for oxygen was in the expected range, but that the value for carbon dioxide was higher than in "mixed venous blood." The aim of the present investigation was to measure the gas concentrations with the same technique in diseased ears, to see if there are any differences in middle ear gases between healthy and diseased ears. In terms of group means, the present measurements in 13 ears of children with otitis media with effusion or atelectasis did not differ from the values previously obtained for healthy ears of adults for any of the gases.

Adolescent↗
PubMedDate not supplied

Shrinking pleuritis with atelectasis. Specificity of abnormalities present at conventional radiography of the lung.

Radiographic appearances claimed to be typical of shrinking pleuritis with atelectasis (SPA) were tested by mingling chest films from 6 SPA patients with those from 56 cancer cases. Two radiologists were asked to interpret the films independently, make a diagnosis, and state what abnormalities could be distinguished. No single abnormality or combination of abnormalities was found to be pathognomonic and the wish to diagnose the SPA cases led to misdiagnosis of cancer in one of 56 cases by each radiologist. To prevent underdiagnosis of cancer, further examinations are required. Careful follow-up of SPA cases, if they are not operated upon, is recommended.

Diagnosis, Differential↗
PubMed2004

Correlation between extravascular lung water and oxygenation in ALI/ARDS patients in septic shock: possible role in the development of atelectasis?

This study aimed to evaluate the relationship between PaO2/FiO2 ratio and extravascular lung water in septic shock-induced acute respiratory distress syndrome in a prospective observational clinical trial. Twenty-three patients suffering from sepsis induced acute respiratory distress syndrome were recruited. All patients were ventilated in pressure control/support mode. Haemodynamic parameters were determined by arterial thermodilution (PiCCO) eight hourly for 72 hours. At the same time blood gas analyses were done and respiratory parameters were also recorded. Data are presented as mean +/-SD. For statistical analysis Pearson's correlation test, and analysis of variance (ANOVA) was used respectively. Significant negative correlation was found between extravascular lung water and PaO2/FiO2 (r = -0.355, P < 0.001), and significant positive correlation was shown between extravascular lung water and PEEP (r=0.557, P<0.001). A post-hoc analysis was performed when "low" PEEP: < 10 cmH2O and "high" PEEP: (10 cmH2O PEEP was applied, and neither the oxygenation, nor the driving pressure or the PaCO2 differed significantly, but the extravascular lung water showed significant difference when "high" or "low" PEEP was applied (13+/-5 vs 9+/-2 ml/kg respectively, P=0.001). This study found significant negative correlation between extravascular lung water and PaO2/FiO2. The mechanism by which extravascular lung water affects oxygenation is unknown but the significant positive correlation between PEEP and extravascular lung water shown in this trial suggests that the latter may have a role in the development of alveolar atelectasis.

Extravascular Lung Water↗
PubMed1981

Round (helical) atelectasis.

Round (helical) atelectasis is a little-known form of pulmonary collapse. It is thought to occur secondary to lung compression from pleural effusion or following therapeutic pneumothorax. Its occurrence is favoured in patients with exudative pleural effusions and extensive pleural thickening. It presents radiographically as a pulmonary pseudotumour, and experience with this entity and its pathogenesis are discussed.

Humans↗
PubMed1991

Round atelectasis in a 20-year-old woman.

Round atelectasis is an unusual pulmonary pseudotumor often associated with primary pleural pathologic conditions or pleural effusion. We report the case of a 20-year-old woman who was found to have a large, circular pulmonary lesion demonstrated on both plain chest x-ray film and computed chest tomography. The patient underwent exploratory thoracotomy, at which time this uncommon entity was identified.

Adult↗
PubMed1995

Asbestos-related rounded atelectasis. Radiologic and mineralogic data in 23 cases.

A retrospective study was conducted in 23 subjects with previous occupational exposure to asbestos and exhibiting rounded atelectasis (RA) on high-resolution computed tomography scan (HRCT scan) to evaluate the retention of asbestos bodies (ABs) using light microscopy in the bronchoalveolar lavage (BAL) fluid or lung parenchyma in such patients. A total of 31 RAs were identified, usually located in the lower (25 RAs) and posterior (23 RAs) parts of the lung. Pleural thickening in contact with the RA was observed in 27 RAs and parenchymal bands were detected in 15 cases. Twelve of the 20 patients who underwent BAL or surgery exhibited significant retention of ABs in BAL fluid or lung tissue. Moreover, a significant retention of ABs was observed in five of nine patients with a history of asbestos exposure but no diffuse pleural thickening on chest radiograph or interstitial opacities on HRCT scan. Patients with RAs and coexisting diffuse pleural thickening and/or interstitial fibrosis should be considered at a higher risk for lung cancer in comparison to patients with isolated circumscribed pleural plaques based on increased AB counts. By contrast, the excess risk of lung cancer is more questionable in patients with only RAs and circumscribed pleural plaques as they may have AB counts either above or below that associated with pleural plaques alone. This emphasizes the need for further follow-up studies to define criteria indicating the need for thoracotomy in these subjects.

Asbestos↗