Effect of re-expansion after short-period lung collapse on pulmonary capillary permeability and pro-inflammatory cytokine gene expression in isolated rabbit lungs.
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BACKGROUND: Re-expansion pulmonary oedema is a rare complication caused by rapid re-expansion of a chronically collapsed lung. Several cases of pulmonary oedema associated with one-lung ventilation (OLV) have been reported recently. Elevated levels of pro-inflammatory cytokines in pulmonary oedema fluid are suggested to play important roles in its development. Activation of cytokines after re-expansion of collapsed lung during OLV has not been thoroughly investigated. Here we investigated the effects of re-expansion of the collapsed lung on pulmonary oedema formation and pro-inflammatory cytokine expression. METHODS: Lungs isolated from female white Japanese rabbits were perfused and divided into a basal (BAS) group (n=7, baseline measurement alone), a control (CONT) group (n=9, ventilated without lung collapse for 120 min) and an atelectasis (ATEL) group (n=9, lung collapsed for 55 min followed by re-expansion and ventilation for 65 min). Pulmonary vascular resistance (PVR) and the coefficient of filtration (Kfc) were measured at baseline and 60 and 120 min. At the end of perfusion, bronchoalveolar lavage fluid/plasma protein ratio (B/P), wet/dry lung weight ratio (W/D) and mRNA expressions of tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and myeloperoxidase (MPO) were determined. RESULTS: TNF-alpha and IL-1beta mRNA were significantly up-regulated in lungs of the ATEL group compared with BAS and CONT, though no significant differences were noted in PVR, Kfc, B/P and W/D within and between groups. MPO increased at 120 min in CONT and ATEL groups. CONCLUSION: Pro-inflammatory cytokines were up-regulated upon re-expansion and ventilation after short-period lung collapse, though no changes were noted in pulmonary capillary permeability. (+info)
Clinical review: the implications of experimental and clinical studies of recruitment maneuvers in acute lung injury.
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Mechanical ventilation can cause and perpetuate lung injury if alveolar overdistension, cyclic collapse, and reopening of alveolar units occur. The use of low tidal volume and limited airway pressure has improved survival in patients with acute lung injury or acute respiratory distress syndrome. The use of recruitment maneuvers has been proposed as an adjunct to mechanical ventilation to re-expand collapsed lung tissue. Many investigators have studied the benefits of recruitment maneuvers in healthy anesthetized patients and in patients ventilated with low positive end-expiratory pressure. However, it is unclear whether recruitment maneuvers are useful when patients with acute lung injury or acute respiratory distress syndrome are ventilated with high positive end-expiratory pressure, and in the presence of lung fibrosis or a stiff chest wall. Moreover, it is unclear whether the use of high airway pressures during recruitment maneuvers can cause bacterial translocation. This article reviews the intrinsic mechanisms of mechanical stress, the controversy regarding clinical use of recruitment maneuvers, and the interactions between lung infection and application of high intrathoracic pressures. (+info)
Diagnosis and management of endobronchial tuberculosis.
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We examined the records of sixty-one patients (17 males and 44 females) with endobronchial tuberculosis (EBTB). Smear tests of acid-fast bacilli were positive in 42 cases and cultures of tubercle bacilli (TB) were positive in 57. The main findings of chest roentgenogram on admission were as follows: no abnormal findings in 8, atelectasis in 30, infiltration in 25, and cavitary lesions in 6. The localization and cross-sectional extension of lesions confirmed bronchoscopically were as follows: trachea in 15, with 3 circular lesions (CLs). Right (R-) main bronchus in 19 with 11 CLs, left (L-) main bronchus in 18 with 11 of CLs, R-truncus intermedius in 14 with 6 of CLs, R-upper lobar bronchus (UB) in 17 with 12 CLs, R-middle lobar bronchus in 14 with 11 of CLs, R-lower lobar bronchus (LB) in 6 with 2 CLs, L-UB in 10 with 7 CLs and L-LB in 3 with 2 CLs. All cases were treated by combination chemotherapy with isoniazid, rifampicin, streptomycin and/or ethambutol and the rate of negative conversion of TB was good, but most of circular lesions resulted in severe bronchial stenosis or complete obstruction during and after chemotherapy, and no improvement was seen in any of the atelectasis cases at the cessation of chemotherapy. We discuss the points of early diagnosis and management of EBTB. (+info)
The influence of cardiopulmonary bypass on respiratory dysfunction in early postoperative period.
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BACKGROUND AND OBJECTIVE: Pulmonary dysfunction is one of the most serious problems in an early postoperative period after cardiac surgery. This study was designed to reveal the impact of performed cardiopulmonary bypass on pulmonary function during early postoperative period by evaluating the intrapulmonary shunt. MATERIAL AND METHODS: Twenty-one patients undergoing elective myocardial revascularization surgery were analyzed. The patients were divided into two groups. Group 1 included 11 patients who underwent cardiac surgery on cardiopulmonary bypass. Group 2 included 10 patients who underwent cardiac surgery without cardiopulmonary bypass. Preoperative data were similar in the both groups. Blood gas analysis for intrapulmonary shunt calculations was made at 20 minutes after the induction of anesthesia and at 4 hours after the surgery. Intrapulmonary shunt size (Qs/Qt) was also calculated and the records were studied for additional data. RESULTS: At 4 hours after surgery Qs/Qt increased, compared to the preoperative data in Group 1 (from 8.6+/-2.1 to 16.8+/-2.6%, p<0.02). Intrapulmonary shunt was great in Group 1 compared with Group 2 at four hours after the surgery (16.8+/-2.6 and 7.8+/-2.1%, p<0.02). In Group 1 80 % of alterations in a pulmonary function were caused by atelectasis, detected by chest X-ray. In Group 2 no increase in intrapulmonary shunt and no atelectasis were determined. CONCLUSIONS: Arterial hypoxemia and increase in intrapulmonary shunt (due to atelectasis) have proven that alterations in pulmonary function are found more often and are more pronounced in patients after surgery on cardiopulmonary bypass. (+info)
Acoustic evidence of airway opening during recruitment in excised dog lungs.
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The aim of this study was to test the hypothesis that the mechanism of recruitment and the lower knee of the pressure-volume curve in the normal lung are primarily determined by airway reopenings via avalanches rather than simple alveolar recruitments. In isolated dog lung lobes, the pressure-volume loops were measured, and crackle sounds were recorded intrabronchially during both the first inflation from the collapsed state to total lobe capacity and a second inflation without prior degassing. The inflation flow contained transients that were accompanied by a series of crackles. Discrete volume increments were estimated from the flow transients, and the energy levels of the corresponding crackles were calculated from the sound recordings. Crackles were concentrated in the early phase of inflation, with the cumulative energy exceeding 90% of its final value by the lower knee of the pressure-volume curve. The values of volume increments were correlated with crackle energy during the flow transient for both the first and the second inflations (r(2) = 0.29-0.73 and 0.68-0.82, respectively). Because the distribution of volume increments followed a power law, the correlation between crackle energy and discrete volume increments suggests that an avalanche-like airway opening process governs the recruitment of collapsed normal lungs. (+info)
Variable ventilation improves perioperative lung function in patients undergoing abdominal aortic aneurysmectomy.
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BACKGROUND: Optimizing perioperative mechanical ventilation remains a significant clinical challenge. Experimental models indicate that "noisy" or variable ventilation (VV)--return of physiologic variability to respiratory rate and tidal volume--improves lung function compared with monotonous control mode ventilation (CV). VV was compared with CV in patients undergoing abdominal aortic aneurysmectomy, a patient group known to be at risk of deteriorating lung function perioperatively. METHODS: After baseline measurements under general anesthesia (CV with a tidal volume of 10 ml/kg and a respiratory rate of 10 breaths/min), patients were randomized to continue CV or switch to VV (computer control of the ventilator at the same minute ventilation but with 376 combinations of respiratory rate and tidal volume). Lung function was measured hourly for the next 6 h during surgery and recovery. RESULTS: Forty-one patients for aneurysmectomy were studied. The characteristics of the patients in the two groups were similar. Repeated-measures analysis of variance (group x time interaction) revealed greater arterial oxygen partial pressure (P = 0.011), lower arterial carbon dioxide partial pressure (P = 0.012), lower dead space ventilation (P = 0.011), increased compliance (P = 0.049), and lower mean peak inspiratory pressure (P = 0.013) with VV. CONCLUSIONS: The VV mode of ventilation significantly improved lung function over CV in patients undergoing abdominal aortic aneurysmectomy. (+info)
Pathophysiology and management of the flail chest.
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Flail chest occurs when a series of adjacent ribs are fractured in at least 2 places, anteriorly and posteriorly. This section of the chest wall becomes unstable and it moves inwards during spontaneous inspiration. The physiological impact of a flail chest depends on multiple factors, including the size of the flail segment, the intrathoracic pressure generated during spontaneous ventilation, and the associated damage to the lung and chest wall. Treatment varies with the severity of the physiologic impairment attributable to the flail segment itself. Immediate surgical fixation may decrease morbidity, but conservative treatment with positive pressure ventilation is preferred when multiple injuries to the intrathoracic organs are present. (+info)
Effects of expiratory rib cage compression combined with endotracheal suctioning on gas exchange in mechanically ventilated rabbits with induced atelectasis.
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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. (+info)