共查询到20条相似文献,搜索用时 15 毫秒
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Lakshminarayan S.; Jindal S. K.; Kirk W.; Butler J. 《Journal of applied physiology》1987,62(6):2358-2361
Since pulmonary blood flow to regions involved in adult respiratory disease syndrome (ARDS) is reduced by hypoxic vasoconstriction, compression by cuffs of edema, and local thromboses, we postulated that the bronchial circulation must enlarge to provide for the inflammatory response. We measured anastomotic bronchial systemic to pulmonary blood flow [QBr(s-p)] serially in a lung lobe in 31 open-chest dogs following a generalized lobar injury simulating ARDS. The pulmonary circulation of the weighed left lower lobe (LLL) was isolated and perfused (zone 2) with autologous blood in anesthetized dogs. QBr(s-p) was measured from the amount of blood which overflowed from this closed vascular circuit corrected by any changes in the lobe weight. The LLL was ventilated with 5% CO2 in air. The systemic blood pressure (volume infusion), gases, and acid-base status (right lung ventilation) were kept constant. We injured the LLL via the airway by instilling either 0.1 N HCl or a mixture of glucose and glucose oxidase or via the pulmonary vessels by injecting either alpha-naphthylthiourea or oleic acid into the LLL pulmonary artery. In both types of injury, there was a prompt rise in QBr(s-p) (mean rise = 247% compared with control), which was sustained for the 2 h of observation. The cause of this increase in flow was studied. Control instillation of normal saline into the airways or into the pulmonary vessels did not change QBr(s-p) nor did a similar increase in lobar fluid (weight) due to hydrostatic edema. Neither cardiac output nor systemic blood pressure increased.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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A series of 31 patients with various degrees of chronic obstructive pulmonary disease underwent right heart catheterization using flow-directed thermodilution catheters. Both rest and supine exercise values were obtained. The patients were divided into two groups on the basis of their reduction in forced expiratory volume in 1 s (FEV1). In patients with FEV1 values of greater than or equal to 1,300 ml (group 1), the arterial oxygen partial pressure (PaO2) did not significantly change with exercise, while in patients with FEV1 of less than or equal to 1,200 ml (group 2) PaO2 significantly (p less than 0.05) fell in response to exercise. In group 2, a significant increase of total pulmonary resistance (TPR) with exercise was found (p less than 0.01). Pulmonary vascular resistance (PVR) remained unchanged in both subgroups. It is suggested that the value of PVR for subgroup 2 is artificially low because an important variable, namely pulmonary artery wedge pressure, is influenced by alveolar pressure in patients with an uneven distribution of perfusion and ventilation at pulmonary venous pressures lower than alveolar pressure. The steeper slope of the pressure-flow relationship in these patients is probably due to an increased vascular tone caused by chronic hypoxia at rest and further fall of PaO2 and rise of arterial CO2 partial pressure in response to exercise. 相似文献
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Agostoni P. G.; Deffebach M. E.; Kirk W.; Mendenhall J. M.; Albert R. K.; Butler J. 《Journal of applied physiology》1987,62(5):1907-1911
Lobar bronchial blood flow has been reported to increase and decrease acutely after pulmonary arterial obstruction (PAO). Because bronchial blood flow (Qbr) to the trachea and bronchi is influenced by inspired air temperature, we investigated whether temperature differences could explain these disparate results. In 10 open-chested dogs the left lower lobe (LLL) was isolated and perfused in situ with autologous blood at a controlled temperature with an independent vascular circuit. The abdomen and the chest of the dog were enclosed in a Plexiglas box in which air was fully humidified and temperature could be regulated. Qbr, determined by the reference flow technique using 16 micron microspheres, was measured before and 30 min after onset of PAO with the air in the box being either at 27 or 39 degrees C and with warmed LLL blood (37 degrees C) in the latter condition. Anastomotic bronchial blood flow [Qbr(s-p), determined as overflow from the closed LLL vascular circuit and measured in ml X min-1 X 100 g dry lung wt-1 X 100 Torr mean systemic pressure-1] was measured continuously at both temperatures. Both before and after PAO, Qbr and Qbr(s-p) were closely correlated: Qbr (ml/min) = 1.12 + 0.978Qbr(s-p); R = 0.912. This was true regardless of the presence or the absence of pulmonary flow, showing that the distribution of bronchial blood flow between the anastomotic and the nonanastomotic portion does not change acutely during PAO. When the air in the box was 27 degrees C, Qbr(s-p) was 19.5 +/- 5.2 (SE) and increased to 38.6 +/- 8.1 with PAO (P less than 0.007).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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M. Umar Qureshi Gareth D. A. Vaughan Christopher Sainsbury Martin Johnson Charles S. Peskin Mette S. Olufsen N. A. Hill 《Biomechanics and modeling in mechanobiology》2014,13(5):1137-1154
A novel multiscale mathematical and computational model of the pulmonary circulation is presented and used to analyse both arterial and venous pressure and flow. This work is a major advance over previous studies by Olufsen et al. (Ann Biomed Eng 28:1281–1299, 2012) which only considered the arterial circulation. For the first three generations of vessels within the pulmonary circulation, geometry is specified from patient-specific measurements obtained using magnetic resonance imaging (MRI). Blood flow and pressure in the larger arteries and veins are predicted using a nonlinear, cross-sectional-area-averaged system of equations for a Newtonian fluid in an elastic tube. Inflow into the main pulmonary artery is obtained from MRI measurements, while pressure entering the left atrium from the main pulmonary vein is kept constant at the normal mean value of 2 mmHg. Each terminal vessel in the network of ‘large’ arteries is connected to its corresponding terminal vein via a network of vessels representing the vascular bed of smaller arteries and veins. We develop and implement an algorithm to calculate the admittance of each vascular bed, using bifurcating structured trees and recursion. The structured-tree models take into account the geometry and material properties of the ‘smaller’ arteries and veins of radii \(\ge \) 50 \(\upmu \) m. We study the effects on flow and pressure associated with three classes of pulmonary hypertension expressed via stiffening of larger and smaller vessels, and vascular rarefaction. The results of simulating these pathological conditions are in agreement with clinical observations, showing that the model has potential for assisting with diagnosis and treatment for circulatory diseases within the lung. 相似文献
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In an attempt to achieve post-inhalation self-regulated insulin release, we constructed a microparticle agglomerate of nano-sized liposomal particles, with the agglomeration facilitated by cross-linkages capable of cleavage by glucose. The particles exhibited a small aerodynamic diameter within the human respirable range, but a large geometric diameter that prevents macrophage uptake and clearance. Upon intratracheal instillation of the "glucose-sensitive" microparticle into the lungs of rats, hyperglycemic events triggered an acceleration of the release of insulin achieving normoglycemia shortly after "sensing" the elevated systemic glucose. This work is a demonstration of an inhalable particle with long residence times in the lungs capable of modulating insulin release based on systemic glucose levels. 相似文献
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Effects of airway pressure on bronchial blood flow 总被引:2,自引:0,他引:2
We studied the effects of increased airway pressure caused by increasing levels of positive end-expiratory pressure (PEEP) on bronchial arterial pressure-flow relationships. In eight alpha-chloralose-anesthetized mechanically ventilated sheep (23-27 kg), the common bronchial artery, the bronchial branch of the bronchoesophageal artery, was cannulated and perfused with a pump. The control bronchial blood flow (avg 12 +/- 1 ml/min or 0.48 ml X min-1 X kg-1) was set to maintain mean bronchial arterial pressure equal to systemic blood pressure. Pressure-flow curves of the bronchial circulation were measured by making step changes in bronchial blood flow, and changes in these curves were analyzed with measurements of the pressure at zero flow and the slope of the linearized curve. The zero-flow pressure represents the effective downstream pressure, and the slope represents the resistance through the bronchial vasculature. At a constant bronchial arterial pressure of 100 mmHg, an 8 mmHg increase in mean airway pressure caused a 40% reduction in bronchial blood flow. Under constant flow conditions, increases in mean airway pressure with the application of PEEP caused substantial increases in bronchial arterial pressure, averaging 4.6 mmHg for every millimeters of mercury increase in mean airway pressure. However, bronchial arterial pressure at zero flow increased approximately one-for-one with increases in mean airway pressure. Thus the acute sensitivity of the bronchial artery to changes in mean airway pressure results primarily from changes in bronchovascular resistance and not downstream pressure. 相似文献
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O G Thilenius 《Journal of applied physiology》1966,21(3):901-904
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目的:探讨肺部感染对支气管封堵治疗影响的动物实验性研究。方法:取健康杂种犬18条,分为3组(A、B、C组)(n=6),经支气管镜每只犬置入致密螺栓状支气管封堵器2枚,其中A、B组为肺部感染组,C组仅为单纯封堵(A、C组封堵后使用抗生素,而B组封堵后未使用抗生素)。观察实验动物的耐受性,定期复查血象、支气管镜、胸部CT扫描,8周后观察封堵器附近支气管组织及远端肺组织变化。结果:观察期内,除1例因给药管不慎封堵入靶支气管内而死亡外,其余犬耐受性良好;截至封堵第8周,36只封堵器中,脱落共有0只(0/36)。胸部CT扫描和组织病理学检查证实,部分封堵的肺叶有萎陷,封堵部位远端肺泡腔缩小,5例封堵部位及其周围有轻度阻塞性炎症改变,未出现肺脓肿及坏死。肺部感染因素对犬的恢复有延迟;而感染组术后肌注抗生素与否,并未能缩短实验动物的不适反应过程,亦未能预防或减少阻塞性炎症的发生。结论:试制的支气管封堵器置入方便,组织相容性好;无论单纯封堵还是肺部感染组的封堵,各组实验动物均有较好的耐受性,但是肺部感染因素对犬的恢复有延迟;肺部感染组术后肌注抗生素与否,对提高动物的耐受程度无明显作用。 相似文献
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