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PubMed2004

Effects of expiratory rib cage compression combined with endotracheal suctioning on gas exchange in mechanically ventilated rabbits with induced atelectasis.

INTRODUCTION: In Japan, expiratory rib cage compression (a chest physiotherapy technique) is frequently used with mechanically ventilated patients. It has not been determined whether rib cage compression combined with endotracheal suctioning improves oxygenation, ventilation, and mucus clearance. We evaluated the effects of rib cage compression with and without endotracheal suctioning on P(aO(2)), P(aCO(2)), dynamic compliance of the respiratory system (C(RS)), and mucus clearance in rabbits with induced atelectasis. METHODS: Anesthetized adult rabbits had an 18-gauge catheter placed into the airway, together with a tracheal tube via tracheostoma, and were mechanically ventilated. To create atelectasis, artificial mucus was infused into the airway via the catheter. Each rabbit was randomly assigned to one of 4 groups (= 7 in each): (1) control, (2) received endotracheal suctioning alone, (3) received rib cage compression alone, and (4) received both rib cage compression and endotracheal suctioning. After these interventions, for 30 min, each animal was placed supine without intervention for 120 min. RESULTS: In the groups that received rib cage compression, oxygenation, ventilation, and C.

Animals↗
PubMed1991

The various faces of right upper lobe atelectasis.

The most common cause of RUL atelectasis in adults is neoplasm obstructing the RUL bronchus. Scarring of the lobe following chronic infection comes next. Other causes of obstruction, whether central or peripheral, are less common. The only direct sign of atelectasis is approximation of the fissures. All other signs are indirect. Increased density of the collapsed lobe is the most noticeable indirect sign. In the absence of adhesions the RUL is fixed at the hilum only. Therefore, it may take any one of the different shapes. Usually it is not difficult to recognize the dense shrunken lobe. Otherwise, we will have to depend on the other indirect signs, namely, displacement of mediastinal structures, elevation of the right hemidiaphragm, juxtaphrenic peak, elevation of hilum, "disappearance" of RUL artery, changes in position of of vascular (and bronchial) markings, and displacement of granuloma (if present).

Bronchial Neoplasms↗
PubMed1991

Scoliosis as cause of pulmonary atelectasis.

We present a patients with persistent position-dependent productive cough and intermittent fever. He was first examined at 38 yrs of age. Chest X-ray showed a severe thoracic lordoscoliosis and an atelectasis of the right lower lobe. Bronchography revealed a total stenosis of the right lower lobe bronchus. Five years later had increased symptoms. Spirometry showed total lung capacity (TLC) 3.8 l (predicted value 6.7 l), forced vital capacity (FVC) 2.6 l (4.8 l) and forced expiratory volume in one second (FEV1) 1.7 l (3.9 l). Bronchoscopy demonstrated a smooth stenosis of the right lower lobe bronchus but the stenosis could be passed through with a brush. Computed tomographic scanning demonstrated compression of the right lower lobe bronchus and the atelectasis. After surgical removal of the right lower lobe, all symptoms disappeared. Histological examination of the right lower lobe revealed fibrosis and chronic inflammation.

Adult↗
PubMed1989

Asbestos-associated rounded atelectasis: a case report and review of the literature.

Asbestos-associated rounded atelectasis is a nonmalignant radiographic consequence of asbestos exposure that can mimic neoplasia. It is infrequently mentioned in reviews of the radiographic features of nonmalignant asbestos-associated disease. Distinguishing it from malignant disease without resorting to chest surgery is important. This report presents a case of such atelectasis, and a review of the relevant literature.

Asbestosis↗
PubMed1986

Influence of inspired oxygen concentration on acceleration atelectasis.

The USAF is developing an On Board Oxygen Generation System (OBOGS) for use in fighter aircraft. This study was conducted to determine the inert gas dilution requirements of the OBOGS necessary to prevent acceleration atelectasis. Human subjects were exposed to either 21, 50, 70, 82.5, 95 or 100% inspired oxygen, along with an increased +Gz Simulated Aerial Combat Maneuver (SACM) profile using the USAF School of Aerospace Medicine human centrifuge. The SACM profile utilized four +4.5z peaks (136 s at this +Gz) superimposed on a +3 Gz baseline, representing a total ride time of 276 s. A significant reduction in vital capacity (VC) occurred at inspired oxygen concentrations of 70% and greater. The addition of 5% argon (a natural product of OBOGS) to pure oxygen did not reduce the magnitude of acceleration atelectasis observed, nor the severity of breathing symptoms. A 30-s exposure to positive pressure breathing at 30 mm Hg during the end of the SACM reduced the level of VC reduction caused by subjects breathing 100% oxygen during +Gz.

Acceleration↗
PubMed1987

Pulmonary mechanics and atelectasis during immersion in oxygen-breathing subjects.

It has been suggested that vital capacity (VC) reduction seen during head-out immersion and oxygen breathing is due to atelectasis formation. In this study VC was reduced in 8 healthy subjects by 8.7% as an effect of immersion per se and by a further 14.3% as an effect of oxygen breathing during 30 min of immersion. Every 2nd min during the exposure, functional residual capacity (FRC), dynamic compliance (C-dyn), and static esophageal pressure at end-expiration (Pes-frc) were measured by body plethysmographic technique. Results were compared with an air-breathing, immersed control situation to evaluate any possible atelectasis formation. The only significant changes during immersion were observed after 30 min of air breathing, where FRC decreased linearly by 8.5% and C-dyn by 13.2%. The main conclusion is that atelectases acting solely as volume restrictors cannot explain the whole VC reduction without other additive or synergistic mechanisms. We suggest that the linear decrements in FRC and C-dyn as an effect of immersion time might be explained by either inspiratory muscle fatigue or increasing thoracic fluid compartment during the first 30 min of head-out immersion.

Adult↗
PubMed1979

Preferential distribution of lobar emphysema and atelectasis in bronchopulmonary dysplasia.

The chest roentgenograms of 142 neonates who survived mechanical ventilation for respiratory distress syndrome (N = 99) and prolonged apnea (N = 43) were reviewed. Thirty-seven infants had bronchopulmonary dysplasia (BPD) and 17 of these developed lobar hyperinflation of the right lower lobe and collapse of the right upper lobe. Regional lung function was measured with a xenon 133 technique in three of these infants and in five other patients who either died or were lost to follow-up. All had BPD with right lower lobe overinflation. Ventilation was less in the lower regions than the upper regions bilaterally (P less than .001), indicating that the hyperinflation of the lower lobes was not compensatory for upper lobe collapse but was due to emphysema. Mean regional perfusion was equal in the upper and lower regions of the chest. This preferential distribution of lobaremphysema and ipsilateral atelectasis in BPD tended to present and regress simultaneously, but in many infants it lasted as long as eight weeks. Only one infant with persistent atelectasis developed pneumonia. The best mode of therapy appears to be supportive.

Apnea↗
PubMed1986

[Surface activity of the surfactant in experimental compression atelectasis].

Surface surfactant activity was studied at different time periods of compression atelectasis, induced by hydrothorax in 35 guinea pigs. The animals were slaughtered 30 and 60 minutes or 3, 12 and 24 hours after hydrothorax. It has been demonstrated that experimental compression atelectasis is accompanied by surface activity lowering, associated with disorders in surfactant secretion into the alveolar lumen. The qualitative composition of surfactant phospholipids remains unchanged, which may play an essential role in the recovery of lung tissue aeration.

Animals↗
PubMed1977

[Pseudo-tumoral round atelectasis without known pleural history (apropos of 2 cases)].

The authors recall two cases of round atelectasis without any known pleural past-record. The first showed, on successive X rays, an increase in size of the image. In the second case a pleural effusion occurred after the discovery of a round opacity. They stress the various small radiological signs as a way of including the etiology of a purely mechanical atelectasis among the difficult diagnosis of intraparenchymal round opacities.

Adult↗
PubMed1983

Positive-pressure oxygen breathing and pulmonary atelectasis during immersion.

The effect on vital capacity of 1 h of oxygen breathing with and without continuous positive pressure was studied in five subjects during immersion. Vital capacity (VC) was used as an index of pulmonary atelectasis. The negative-pressure breathing induced by head-out immersion will cause airway closure and thus atelectasis if the closed-off regions contain oxygen. Without positive-pressure breathing, VC was reduced by 42%, and the subjects complained of tightness in the chest and had attacks of coughing. When 1.5 kPa positive pressure was used, three subjects had no decrease in VC, and in the remaining two subjects the decrease was halved. The latter two subjects were also studied during continuous positive-pressure oxygen breathing at 2.5 kPa. The decrease in VC was only one-fifth of the decrease in the control immersion condition without positive pressure (0 kPa), and they had no subjective feelings of discomfort. The results are relevant for the design of closed-circuit oxygen breathing apparatus.

Adult↗
PubMed1994

[Blood flow pattern in pulmonary atelectasis with color Doppler flow imaging].

Blood flow pattern in the lesion was evaluated in 4 patients with pulmonary atelectasis by color Doppler flow imaging synchronized electrocardiography. The pulsatile signal and triphasic signal were detected, whereas the continuous signal was not. It seemed that in pulmonary atelectasis the pulsatile signal was the blood flow signal in the pulmonary artery and the triphasic signal was the blood flow signal in the pulmonary vein.

Aged↗
PubMed1994

Atelectasis formation and gas exchange impairment during anaesthesia.

Anaesthesia is accompanied by impaired oxygenation of the blood, and sometimes hypoxaemia may develop despite an increased oxygen fraction of the inspired gas. The major cause of this derangement is shunt, an effect of prompt atelectasis formation in dependent lung regions. An additional cause is ventilation/perfusion (V/Q) mismatch, possibly produced by intermittent airway closure. The magnitude of shunt and size of atelectasis are independent of the age of the patient, whereas V/Q mismatch increases with age, explaining the age dependent impairment of oxygenation.

Age Factors↗
PubMed1994

[A case report of rounded atelectasis on MRI].

A 73-year-old man was admitted to Toyama Red Cross Hospital, because of productive cough and right flank pain. His chest X-ray film and computed tomography (CT) showed pleural effusion and a mass shadow in the right lung area. On CT vessels and bronchi were seen curving toward the mass (comet tail sign), suggesting rounded atelectasis. Transthoracic lung biopsy under CT and echo guidance revealed suppurative pleuritis. MRI also showed the comet tail sign. Moreover, in the lesion, curling hypointense lines were observed on various slices. We describe how MRI facilitates the diagnosis of rounded atelectasis.

Aged↗
PubMed1993

Mechanism of gravity-dependent atelectasis. Analysis by nonradioactive xenon-enhanced dynamic computed tomography.

RATIONALE AND OBJECTIVES: The physiologic mechanism of gravity-dependent atelectasis (GDA), a common finding identified during anesthesia, is not well understood. The purpose of this study was to determine whether an inherent reduction in alveolar volume or a reduction in alveolar ventilation is the more important causative factor for the development of GDA in an experimental animal model. METHODS: After uniform reduction of lung volume in ten rabbits by artificially induced pneumoperitoneum, dynamic inhalation computed tomography (CT) was performed using 50% nonradioactive xenon in oxygen. Time-CT attenuation value curves were fitted to an exponential function, CT value = a - b x e(-kt), and K value, which is proportional to the alveolar ventilation/alveolar volume ratio, was calculated by regression analysis. RESULTS: Gravity-dependent atelectasis occurred only in 5 of 10 rabbits. In this group, K values in the dorsal regions increased before the appearance of GDA. No significant change in K values in the ventral regions was observed. CONCLUSION: One mechanism of GDA may be a preferential reduction in alveolar volume without small airway collapse rather than alveolar volume loss secondary to decreased ventilation.

Animals↗
PubMed1993

[Rounded atelectasis with emphasis on its wide spectrum].

While rounded atelectasis (RA) is considered to be rather common in the United States and Europe, the total number of RA cases reported from Japan still remains approximately 30. We have long been aware that there are many variations in the radiographic appearance of so-called RA and that RA has never been clearly defined. We retrospectively reviewed 22 cases collected as RA and its variants from several institutions. We defined RA as "peripheral atelectasis mimicking tumor secondary to shrinkage or bending of the pleura of various degrees, and accompanied by lung distortion." The diagnostic criteria of typical RA include (1) peripheral tumoral shadow in contact with pleural effusion or thickened pleura, (2) acute angle between the pleura and the shadow, (3) convergence of the pulmonary vessels and bronchi and (4) volume loss of the affected lobe. However, there are cases which lack some of these criteria but are considered to be included in the broad category of RA. We propose that RA should be considered to be an entity having a wide spectrum. Typical lesions showing "cranial tilting" of Hanke are on one side of the spectrum and small linear or strand shadows extending from the thickened pleura are on the other.

Adult↗
PubMed1996

[Hemilateral hydrothorax and atelectasis during laparoscopic Nissen fundoplication].

A 57-year-old woman, weighing 75 kg, with gastroesophageal sliding hernia, received laparoscopic Nissen fundoplication under general anesthesia. Although artificial ventilation was carried out uneventfully when the surgery started, sudden decreases in SpO2 and thoraco-pulmonary compliance were noted after insufflation of CO2. Breath sound was not audible on the left lung. We suspected that inadvertent pneumothorax was produced, but chest X-ray and transesophageal echocardiography at the end of surgery revealed the presence of left hemilateral hydrothorax with pulmonary atelectasis. She was ventilated artificially and given diuretics and albumin solution for 3-days before extubation. We speculated on two reasons for the event: a possibility of perforation of the diaphragm manipulated by surgeons, and that of transition of fluid used for irrigation just below the diaphragm. Pulmonary atelectasis could be induced with hemilateral lung ventilation because cephalad shifting of the diaphragm might follow the intraperitoneal insufflation. We conclude that laparoscopic surgery with insufflation of gas and irrigation with fluid requires careful attention if the laparoscopic surgery is sustained with insufflation and irrigation.

Anesthesia, General↗
PubMed1977

The nature of failure of pulmonary adaptation to atelectasis.

The ability of the lung to decrease blood flow to an atelectatic lobe and to increase flow to normal after reinflation was investigated with a model using left lower lobe atelectasis (LLLA) in the dog. The change in the shunt fraction QS/Qt with continuing LLLA was assumed to represent a change in blood flow to the LLL. With LLLA the Qs/Qt rose from 0.112 to 0.172 and then decreased to 0.119 by the end of 2 hours at the rate of -17%/hour. Reversal of atelectasis for varying times demonstrated that the pulmonary vasoconstrictive response persisted for at least 4 hours after reinflation of LLLA. With LLL ischemia for 1 and 2 hours followed by LLLA, Qs/Qt decreased, but at a rate less than the controls, whereas after hemorrhagic shock with venous reinfusion and LLLA, the Qs/Qt did not decrease. When hemorrhagic shock was followed by arterial reinfusion, 60% had a normal response to LLLA; 40% did not. There was no difference in PVR in these two groups. Pulmonary extravascular water in both groups was the same as in controls. Infusion of NE after 3 hours of LLLA caused Qs/Qt to rise from 0.125 to 0.248, comparable to the value immediately after onset of LLLA. EPi had similar results. Catecholamines may restore blood flow to the atelectatic lobe by causing a maximum generalized pulmonary vasocontriction or by overexpansion of the pulmonary blood volume secondary to peripheral vasoconstriction and thereby abolish any differential in pulmonary vascular resistance across the lung. The early hypoxemia of adult respiratory distress syndrome may arise not on the basis of any intrinsic lung pathology but rather as the result of a normal response of the lung to increased catecholamines.

Animals↗