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Negrini D, Moriondo A, Mukenge S. Comments to Bodega et al. (2015). Respir Physiol Neurobiol 2015; 210:51-2. [PMID: 25617489 DOI: 10.1016/j.resp.2015.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 01/09/2015] [Indexed: 10/24/2022]
Affiliation(s)
- Daniela Negrini
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy.
| | - Andrea Moriondo
- Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy
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Negrini D, Moriondo A. Pleural function and lymphatics. Acta Physiol (Oxf) 2013; 207:244-59. [PMID: 23009260 DOI: 10.1111/apha.12016] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 07/24/2012] [Accepted: 09/17/2012] [Indexed: 11/26/2022]
Abstract
The pleural space plays an important role in respiratory function as the negative intrapleural pressure regimen ensures lung expansion and in the mean time maintains the tight mechanical coupling between the lung and the chest wall. The efficiency of the lung-chest wall coupling depends upon pleural liquid volume, which in turn reflects the balance between the filtration of fluid into and its egress out of the cavity. While filtration occurs through a single mechanism passively driving fluid from the interstitium of the parietal pleura into the cavity, several mechanisms may co-operate to remove pleural fluid. Among these, the pleural lymphatic system emerges as the most important one in quantitative terms and the only one able to cope with variable pleural fluid volume and drainage requirements. In this review, we present a detailed account of the actual knowledge on: (a) the complex morphology of the pleural lymphatic system, (b) the mechanism supporting pleural lymph formation and propulsion, (c) the dependence of pleural lymphatic function upon local tissue mechanics and (d) the effect of lymphatic inefficiency in the development of clinically severe pleural and, more in general, respiratory pathologies.
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Affiliation(s)
- D. Negrini
- Department of Surgical and Morphological Sciences; University of Insubria; Varese; Italy
| | - A. Moriondo
- Department of Surgical and Morphological Sciences; University of Insubria; Varese; Italy
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The role of proteoglycans in pulmonary edema development. Intensive Care Med 2008; 34:610-8. [PMID: 18264693 DOI: 10.1007/s00134-007-0962-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Accepted: 07/20/2007] [Indexed: 10/22/2022]
Abstract
Pulmonary gas exchange critically depends upon the hydration state and the thinness of the interstitial tissue layer within the alveolo-capillary membrane. In the interstitium, fluid freely moving within the fibrous extracellular matrix (ECM) equilibrates with water chemically bound to hyaluronic acid and proteoglycans (PGs). The dynamic equilibrium between these two phases is set and maintained by the transendothelial fluid and solutes exchanges, by the convective outflows into the lymphatic system, and by the mechanical and hydrophilic properties of the solid elements of the ECM. The fibrous ECM components, in particular the chondroitin sulfate proteoglycan (CS-PG) and the heparan-sulfate proteoglycan (HS-PG) families, play a major role in the maintenance of tissue fluid homeostasis. In fact, they provide: (a) a perivascular and interstitial highly restrictive sieve with respect to plasma proteins, thus modulating both interstitial protein concentration and transendothelial fluid filtration; (b) a mechanical support to lymphatic vessels sustaining and modulating their draining function, and (c) a rigid three-dimensional low-compliant scaffold opposing fluid accumulation into the interstitial space. Fragmentation of PG induced by increased plasma volume, by degradation through proteolytic or inflammatory agents, by exposure to inspiratory gas mixture with modified oxygen fraction, or by increased tissue strain/stress invariably results in the progressive loosening of PG intermolecular bonds with other ECM components. The loss of the PGs regulatory functions compromises the protective role of the tissue solid matrix progressively leading to interstitial and eventually severe lung edema.
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The Extracellular Matrix of the Lung: The Forgotten Friend! Intensive Care Med 2007. [DOI: 10.1007/978-0-387-49518-7_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Agostoni E, Zocchi L. Pleural liquid and its exchanges. Respir Physiol Neurobiol 2007; 159:311-23. [PMID: 17884738 DOI: 10.1016/j.resp.2007.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 07/04/2007] [Accepted: 07/04/2007] [Indexed: 11/18/2022]
Abstract
After an account on morphological features of visceral and parietal pleura, mechanical coupling between lung and chest wall is outlined. Volume of pleural liquid is considered along with its thickness in various regions, and its composition. Pleural liquid pressure (P(liq)) and pressure exerted by lung recoil in various species and postures are then compared, and the vertical gradient of P(liq) considered. Implications of lower P(liq) in the lung zone than in the costo-phrenic sinus at iso-height are pointed out. Mesothelial permeability to H(2)O, Cl(-), Na(+), mannitol, sucrose, inulin, albumin, and various size dextrans is provided, along with paracellular "pore" radius of mesothelium. Pleural liquid is produced by filtration from parietal pleura capillaries according to Starling forces. It is removed by absorption in visceral pleura capillaries according to Starling forces (at least in some species), lymphatic drainage through stomata of parietal mesothelium (essential to remove cells, particles, and large macromolecules), solute-coupled liquid absorption, and transcytosis through mesothelium.
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Affiliation(s)
- Emilio Agostoni
- Istituto di Fisiologia Umana I, Università di Milano, Via Mangiagalli 32, 20133, Milano, Italy.
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Moriondo A, Mukenge S, Negrini D. Transmural pressure in rat initial subpleural lymphatics during spontaneous or mechanical ventilation. Am J Physiol Heart Circ Physiol 2005; 289:H263-9. [PMID: 15833809 DOI: 10.1152/ajpheart.00060.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role played by the mechanical tissue stress in supporting lymph formation and propulsion in thoracic tissues was studied in deeply anesthetized rats (n = 13) during spontaneous breathing or mechanical ventilation. After arterial and venous catheterization and insertion of an intratracheal cannula, fluorescent dextrans were injected intrapleurally to serve as lymphatic markers. After 2 h, the fluorescent intercostal lymphatics were identified, and the hydraulic pressure in lymphatic vessels (P lymph) and adjacent interstitial space (P int) was measured using micropuncture. During spontaneous breathing, end-expiratory P lymph and corresponding P int were -2.5 +/- 1.1 (SE) and 3.1 +/- 0.7 mmHg (P < 0.01), which dropped to -21.1 +/- 1.3 and -12.2 +/- 1.3 mmHg, respectively, at end inspiration. During mechanical ventilation with air at zero end-expiratory alveolar pressure, P lymph and P int were essentially unchanged at end expiration, but, at variance with spontaneous breathing, they increased at end inspiration to 28.1 +/- 7.9 and 28.2 +/- 6.3 mmHg, respectively. The hydraulic transmural pressure gradient (DeltaP tm = P lymph - P int) was in favor of lymph formation throughout the whole respiratory cycle (DeltaP tm = -6.8 +/- 1.2 mmHg) during spontaneous breathing but not during mechanical ventilation (DeltaP tm = -1.1 +/- 1.8 mmHg). Therefore, data suggest that local tissue stress associated with the active contraction of respiratory muscles is required to support an efficient lymphatic drainage from the thoracic tissues.
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Affiliation(s)
- Andrea Moriondo
- Dipartimento di Scienze Biomediche Sperimentali e Cliniche, Università degli Studi dell'Insubria, Via J.H. Dunant 5, 21100 Varese, Italy
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Bull JL, Reickert CA, Tredici S, Komori E, Frank EL, Brant DO, Grotberg JB, Hirschl RB. Flow Limitation in Liquid-Filled Lungs: Effects of Liquid Properties. J Biomech Eng 2005; 127:630-6. [PMID: 16121533 DOI: 10.1115/1.1934099] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Flow limitation in liquid-filled lungs is examined in intact rabbit experiments and a theoretical model. Flow limitation (“choked” flow) occurs when the expiratory flow reaches a maximum value and further increases in driving pressure do not increase the flow. In total liquid ventilation this is characterized by the sudden development of excessively negative airway pressures and airway collapse at the choke point. The occurrence of flow limitation limits the efficacy of total liquid ventilation by reducing the minute ventilation. In this paper we investigate the effects of liquid properties on flow limitation in liquid-filled lungs. It is found that the behavior of liquids with similar densities and viscosities can be quite different. The results of the theoretical model, which incorporates alveolar compliance and airway resistance, agrees qualitatively well with the experimental results. Lung compliance and airway resistance are shown to vary with the perfluorocarbon liquid used to fill the lungs. Surfactant is found to modify the interfacial tension between saline and perfluorocarbon, and surfactant activity at the interface of perfluorocarbon and the native aqueous lining of the lungs appears to induce hysteresis in pressure–volume curves for liquid-filled lungs. Ventilation with a liquid that results in low viscous resistance and high elastic recoil can reduce the amount of liquid remaining in the lungs when choke occurs, and, therefore, may be desirable for liquid ventilation.
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Affiliation(s)
- Joseph L Bull
- Department of Biomedical Engineering, The University of Michigan, Ann Arbor, MI 48109, USA.
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Abstract
The pleural space separating the lung and chest wall of mammals contains a small amount of liquid that lubricates the pleural surfaces during breathing. Recent studies have pointed to a conceptual understanding of the pleural space that is different from the one advocated some 30 years ago in this journal. The fundamental concept is that pleural surface pressure, the result of the opposing recoils of the lung and chest wall, is the major determinant of the pressure in the pleural liquid. Pleural liquid is not in hydrostatic equilibrium because the vertical gradient in pleural liquid pressure, determined by the vertical gradient in pleural surface pressure, does not equal the hydrostatic gradient. As a result, a viscous flow of pleural liquid occurs in the pleural space. Ventilatory and cardiogenic motions serve to redistribute pleural liquid and minimize contact between the pleural surfaces. Pleural liquid is a microvascular filtrate from parietal pleural capillaries in the chest wall. Homeostasis in pleural liquid volume is achieved by an adjustment of the pleural liquid thickness to the filtration rate that is matched by an outflow via lymphatic stomata.
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Affiliation(s)
- Stephen J Lai-Fook
- Center for Biomedical Engineering, Wenner-Gren Research Laboratory, Univ. of Kentucky, Lexington, KY 40506-0070, USA.
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Haber R, Grotberg JB, Glucksberg MR, Miserocchi G, Venturoli D, Del Fabbro M, Waters CM. Steady-state pleural fluid flow and pressure and the effects of lung buoyancy. J Biomech Eng 2001; 123:485-92. [PMID: 11601734 DOI: 10.1115/1.1392317] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Both theoretical and experimental studies of pleural fluid dynamics and lung buoyancy during steady-state, apneic conditions are presented. The theory shows that steady-state, top-to-bottom pleural-liquid flow creates a pressure distribution that opposes lung buoyancy. These two forces may balance, permitting dynamic lung floating, but when they do not, pleural-pleural contact is required. The animal experiments examine pleural-liquid pressure distributions in response to simulated reduced gravity, achieved by lung inflation with perfluorocarbon liquid as compared to air. The resulting decrease in lung buoyancy modifies the force balance in the pleural fluid, which is reflected in its vertical pressure gradient. The data and model show that the decrease in buoyancy with perfluorocarbon inflation causes the vertical pressure gradient to approach hydrostatic. In the microgravity analogue, the pleural pressures would be toward a more uniform distribution, consistent with ventilation studies during space flight. The pleural liquid turnover predicted by the model is computed and found to be comparable to experimental values from the literature. The model provides the flow field, which can be used to develop a full transport theory for molecular and cellular constituents that are found in pleural fluid.
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Affiliation(s)
- R Haber
- Biomedical Engineering Department, University of Michigan, Ann Arbor 48109, USA
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Abstract
1. Hydraulic pressure in intercostal and diaphragmatic lymphatic vessels was measured through the micropuncture technique in 23 anaesthetised paralysed rabbits. Pleural lymphatic vessels with diameters ranging from 55 to 950 microm were observed under stereomicroscope view about 3-4 h after intrapleural injection of 20 % fluorescent dextrans. 2. Lymphatic pressure oscillated from a minimum (Pmin) to a maximum (Pmax) value, reflecting oscillations in phase with cardiac activity (cardiogenic oscillations) and lymphatic myogenic activity. With intact pleural space, Pmin in submesothelial diaphragmatic lymphatic vessels of the lateral apposition zone was -9.1 +/- 4.2 mmHg, more subatmospheric than the simultaneously recorded pleural liquid pressure amounting to -3.9 +/- 1.2 mmHg. In extrapleural intercostal lymphatic vessels Pmin averaged -1.3 +/- 2. 7 mmHg. 3. Cardiogenic pressure oscillations (Pmax - Pmin), were observed in all recordings; their mean amplitude was about 5 mmHg and was not dependent upon frequency of cardiac contraction, nor lymphatic vessel diameter, nor the Pmin value. 4. Intrinsic contractions of lymphatic vessel walls caused spontaneous pressure waves of about 7 mmHg in amplitude at a rate of 8 cycles min-1. 5. These results demonstrated the ability of pleural lymphatic vessels to generate pressure oscillations driving fluid from the subatmospheric pleural space into the lymphatic network.
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Affiliation(s)
- D Negrini
- Istituto di Fisiologia Umana I, Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, 20133 Milano, Italy
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11
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Abstract
The pleural space provides the mechanical coupling between lung and chest wall: two views about this coupling are reported and discussed. Information on volume, composition, thickness, and pressure of the pleural liquid under physiologic conditions in a few species is provided. The Starling pressures of the parietal pleura filtering liquid into pleural space, and those of the visceral pleura absorbing liquid from the space are considered along with the permeability of the mesothelium. Information on the lymphatic drainage through the parietal pleura and on the solute-coupled liquid absorption from the pleural space under physiologic conditions and with various kinds of hydrothorax are provided.
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Affiliation(s)
- E Agostoni
- 1st Institute of Human Physiology, University of Milan, Italy
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Brown RE, Butler JP, Godleski JJ, Loring SH. The elephant's respiratory system: adaptations to gravitational stress. RESPIRATION PHYSIOLOGY 1997; 109:177-94. [PMID: 9299649 DOI: 10.1016/s0034-5687(97)00038-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Elephants have had to adapt to gravitational stresses imposed on their very large respiratory structures. We describe some unusual features of the elephant's respiratory system and speculate on their functional significance. A distensible network of collagen fibers fills the pleural space, loosely connects lung to chest wall but appears not to constrain lung-chest wall movements. Myriad spaces within the network and its rich supply of capillaries suggest effective local sources and sinks for pleural fluid that may replace the gravity-dependent flows of smaller mammals. The lung is partitioned into approximately equal to 1 cm3 parenchymal units by a system of thick, elastic septa that ramify throughout the lung from origins on the lung's elastic external capsule. Parenchymal units suspended upon the elastic septal system protect dependent alveoli from compression, thereby reducing the usual gravitational gradient of lung expansion. Intra-pulmonary airways are devoid of cartilage, instead they appear to derive resistance to collapse from tethering forces of the attached septa.
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Affiliation(s)
- R E Brown
- Physiology Program, School of Public Health, Harvard University, Boston, MA 02115, USA
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Perez F, Fernandez P, Hernaiz MI, Jackson EG, Lai-Fook SJ, Boynton BR. Pleural pressure measured in the zone of apposition of diaphragm to rib cage in rabbits. Lung 1993; 171:345-53. [PMID: 8295429 DOI: 10.1007/bf00165700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In 10 anesthetized adult rabbits, we studied the effect of spontaneous breathing and positive pressure ventilation on pleural pressure on the costal lung surface (Ppl) and in the zone of apposition of the rib cage to the diaphragm (Papp). Ppl and Papp were measured by rib capsules installed in the 5th or 6th rib and 11th or 12th rib, respectively. Esophageal (Pes) and gastric (Pga) pressures were measured with air-filled balloons. At end expiration (functional residual capacity), Ppl was subatmospheric (-2.5 +/- 1.4 cm H2O), decreased during spontaneous inspiration, and was in phase with Pes. In contrast, Papp was above atmospheric pressure (2.1 +/- 1.8 cm H2O), increased during inspiration, and was in phase with Pga. Papp lagged Ppl by 180 degrees during spontaneous inspiration but was in phase with Ppl during mechanical ventilation. Changes in Ppl (delta Ppl) during inspiration were greater in magnitude than either delta Papp or delta Pga. Changes in transdiaphragmatic pressure in the zone of apposition (delta Pga-delta Papp) were near zero (-0.4 +/- 0.3 cm H2O), much smaller in magnitude than those (delta Pga-delta Ppl) associated with the lung (3.0 +/- 1.5 cm H2O). These results are consistent with the concept that during breathing, abdominal pressure is transmitted to the zone of apposition of the rib cage to the abdomen. During spontaneous breathing at rest, the pleural space in the zone of apposition is mechanically independent of the pleural space associated with the lung.
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Affiliation(s)
- F Perez
- Department of Pediatrics, Wenner-Gren Research Laboratory, University of Kentucky, Lexington 40506-0070
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