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Langleben D, Orfanos SE, Giovinazzo M, Schlesinger RD, Naeije R, Fox BD, Abualsaud AO, Blenkhorn F, Rudski LG, Catravas JD. Pulmonary capillary surface area in supine exercising humans: demonstration of vascular recruitment. Am J Physiol Lung Cell Mol Physiol 2019; 317:L361-L368. [PMID: 31242024 DOI: 10.1152/ajplung.00098.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In exercising humans, cardiac output (CO) increases, with minor increases in pulmonary artery pressure (PAP). It is unknown if the CO is accommodated via distention of already perfused capillaries or via recruitment of nonconcomitantly perfused pulmonary capillaries. Ten subjects (9 female) performed symptom-limited exercise. Six had resting mean PAP (PAPm) <20 mmHg, and four had PAPm between 21 and 24 mmHg. The first-pass pulmonary circulatory metabolism of [3H]benzoyl-Phe-Ala-Pro (BPAP) was measured at rest and at peak exercise, and functional capillary surface area (FCSA) was calculated. Data are means ± SD. Mean pulmonary arterial pressure rose from 18.8 ± 3.3 SD mmHg to 28.5 ± 4.6 SD mmHg, CO from 6.4 ± 1.6 to 13.4 ± 2.9 L/min, and pulmonary artery wedge pressure from 14 ± 3.3 to 19.5 ± 5 mmHg (all P ≤ 0.001). Percent BPAP metabolism fell from 74.7 ± 0.1% to 67.1 ± 0.1%, and FCSA/body surface area (BSA) rose from 2,939 ± 640 to 5,018 ± 1,032 mL·min-1·m-2 (all P < 0.001). In nine subjects, the FCSA/BSA-to-CO relationship suggested principally capillary recruitment and not distention. In subject 10, a marathon runner, resting CO and FCSA/BSA were high, and increases with exercise suggested distention. Exercising humans demonstrate pulmonary capillary recruitment and distention. At moderate resting CO, increasing blood flow causes principally recruitment while, based on one subject, when exercise begins at high CO, further increases appear to cause distention. Our findings clarify an important physiologic question. The technique may provide a means for further understanding exercise physiology, its limitation in pulmonary hypertension, and responses to therapy.
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Affiliation(s)
- David Langleben
- Center for Pulmonary Vascular Disease, Division of Cardiology, Azrieli Heart Center, and Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Stylianos E Orfanos
- Pulmonary Hypertension Clinic, Attikon Hospital, and 2nd Department of Critical Care, National and Kapodistrian University of Athens, Athens, Greece
| | - Michele Giovinazzo
- Center for Pulmonary Vascular Disease, Division of Cardiology, Azrieli Heart Center, and Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Robert D Schlesinger
- Center for Pulmonary Vascular Disease, Division of Cardiology, Azrieli Heart Center, and Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Robert Naeije
- Faculty of Medicine, Department of Pathophysiology, Free University of Brussels, Brussels, Belgium
| | - Benjamin D Fox
- Pulmonary Hypertension Clinic and Department of Respiratory Medicine, Yitzhak Shamir Hospital, Tel Aviv University, Tzrifin, Israel
| | - Ali O Abualsaud
- Center for Pulmonary Vascular Disease, Division of Cardiology, Azrieli Heart Center, and Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Fay Blenkhorn
- Center for Pulmonary Vascular Disease, Division of Cardiology, Azrieli Heart Center, and Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Lawrence G Rudski
- Center for Pulmonary Vascular Disease, Division of Cardiology, Azrieli Heart Center, and Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - John D Catravas
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia
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Abstract
The pulmonary circulation carries deoxygenated blood from the systemic veins through the pulmonary arteries to be oxygenated in the capillaries that line the walls of the pulmonary alveoli. The pulmonary circulation carries the cardiac output with a relatively low driving pressure, and so differs considerably in structure and function from the systemic circulation to maintain a low-resistance vascular system. The pulmonary circulation is often considered to be a quasi-static system in both experimental and computational studies of pulmonary perfusion and its matching to ventilation (air flow) for exchange. However, the system is highly dynamic, with cardiac output and regional perfusion changing with posture, exercise, and over time. Here we review this dynamic system, with a focus on understanding the physiology of pulmonary vascular dynamics across spatial and temporal scales, and the changes to these dynamics that are reflective of disease. © 2019 American Physiological Society. Compr Physiol 9:1081-1100, 2019.
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Affiliation(s)
- Alys Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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3
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Wagner WW, Jaryszak EM, Peterson AJ, Doerschuk CM, Bohlen HG, King JAC, Tanner JA, Crockett ES, Glenny RW, Presson RG. A perpetual switching system in pulmonary capillaries. J Appl Physiol (1985) 2019; 126:494-501. [PMID: 30571293 PMCID: PMC6397411 DOI: 10.1152/japplphysiol.00507.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 12/14/2018] [Accepted: 12/17/2018] [Indexed: 12/13/2022] Open
Abstract
Of the 300 billion capillaries in the human lung, a small fraction meet normal oxygen requirements at rest, with the remainder forming a large reserve. The maximum oxygen demands of the acute stress response require that the reserve capillaries are rapidly recruited. To remain primed for emergencies, the normal cardiac output must be parceled throughout the capillary bed to maintain low opening pressures. The flow-distributing system requires complex switching. Because the pulmonary microcirculation contains contractile machinery, one hypothesis posits an active switching system. The opposing hypothesis is based on passive switching that requires no regulation. Both hypotheses were tested ex vivo in canine lung lobes. The lobes were perfused first with autologous blood, and capillary switching patterns were recorded by videomicroscopy. Next, the vasculature of the lobes was saline flushed, fixed by glutaraldehyde perfusion, flushed again, and then reperfused with the original, unfixed blood. Flow patterns through the same capillaries were recorded again. The 16-min-long videos were divided into 4-s increments. Each capillary segment was recorded as being perfused if at least one red blood cell crossed the entire segment. Otherwise it was recorded as unperfused. These binary measurements were made manually for each segment during every 4 s throughout the 16-min recordings of the fresh and fixed capillaries (>60,000 measurements). Unexpectedly, the switching patterns did not change after fixation. We conclude that the pulmonary capillaries can remain primed for emergencies without requiring regulation: no detectors, no feedback loops, and no effectors-a rare system in biology. NEW & NOTEWORTHY The fluctuating flow patterns of red blood cells within the pulmonary capillary networks have been assumed to be actively controlled within the pulmonary microcirculation. Here we show that the capillary flow switching patterns in the same network are the same whether the lungs are fresh or fixed. This unexpected observation can be successfully explained by a new model of pulmonary capillary flow based on chaos theory and fractal mathematics.
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Affiliation(s)
- Wiltz W Wagner
- Department of Anesthesiology, Indiana University School of Medicine , Indianapolis, Indiana
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine , Indianapolis, Indiana
- Department of Molecular and Cellular Pharmacology, Department of Physiology and Cell Biology, Center for Lung Biology, University of South Alabama , Mobile, Alabama
| | - Eric M Jaryszak
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Amanda J Peterson
- Department of Anesthesiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Claire M Doerschuk
- Center for Airways Disease, Department of Medicine, University of North Carolina , Chapel Hill, North Carolina
| | - H Glenn Bohlen
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Judy A C King
- Department of Molecular and Cellular Pharmacology, Department of Physiology and Cell Biology, Center for Lung Biology, University of South Alabama , Mobile, Alabama
| | - Judith A Tanner
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Edward S Crockett
- Department of Molecular and Cellular Pharmacology, Department of Physiology and Cell Biology, Center for Lung Biology, University of South Alabama , Mobile, Alabama
| | - Robb W Glenny
- Departments of Medicine and of Physiology and Biophysics, University of Washington , Seattle, Washington
| | - Robert G Presson
- Department of Anesthesiology, Indiana University School of Medicine , Indianapolis, Indiana
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4
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Glenny RW, Robertson HT. Spatial distribution of ventilation and perfusion: mechanisms and regulation. Compr Physiol 2013; 1:375-95. [PMID: 23737178 DOI: 10.1002/cphy.c100002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
With increasing spatial resolution of regional ventilation and perfusion, it has become more apparent that ventilation and blood flow are quite heterogeneous in the lung. A number of mechanisms contribute to this regional variability, including hydrostatic gradients, pleural pressure gradients, lung compressibility, and the geometry of the airway and vascular trees. Despite this marked heterogeneity in both ventilation and perfusion, efficient gas exchange is possible through the close regional matching of the two. Passive mechanisms, such as the shared effect of gravity and the matched branching of vascular and airway trees, create efficient gas exchange through the strong correlation between ventilation and perfusion. Active mechanisms that match local ventilation and perfusion play little if no role in the normal healthy lung but are important under pathologic conditions.
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Affiliation(s)
- Robb W Glenny
- Department of Medicine, University of Washington, USA.
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5
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Frevert U, Nacer A, Cabrera M, Movila A, Leberl M. Imaging Plasmodium immunobiology in the liver, brain, and lung. Parasitol Int 2013; 63:171-86. [PMID: 24076429 DOI: 10.1016/j.parint.2013.09.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 08/28/2013] [Accepted: 09/18/2013] [Indexed: 01/10/2023]
Abstract
Plasmodium falciparum malaria is responsible for the deaths of over half a million African children annually. Until a decade ago, dynamic analysis of the malaria parasite was limited to in vitro systems with the typical limitations associated with 2D monocultures or entirely artificial surfaces. Due to extremely low parasite densities, the liver was considered a black box in terms of Plasmodium sporozoite invasion, liver stage development, and merozoite release into the blood. Further, nothing was known about the behavior of blood stage parasites in organs such as the brain where clinical signs manifest and the ensuing immune response of the host that may ultimately result in a fatal outcome. The advent of fluorescent parasites, advances in imaging technology, and availability of an ever-increasing number of cellular and molecular probes have helped illuminate many steps along the pathogenetic cascade of this deadly tropical parasite.
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Affiliation(s)
- Ute Frevert
- Division of Medical Parasitology, Department of Microbiology, New York University School of Medicine, 341 E 25 Street, New York, NY 10010, USA.
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Suarez-Sipmann F, Santos A, Peces-Barba G, Bohm SH, Gracia JL, Calderón P, Tusman G. Pulmonary artery pulsatility is the main cause of cardiogenic oscillations. J Clin Monit Comput 2012; 27:47-53. [PMID: 22911273 DOI: 10.1007/s10877-012-9391-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 08/09/2012] [Indexed: 11/25/2022]
Abstract
The genesis of cardiogenic oscillations, i.e. the small waves in airway pressure (COS(paw)) and flow (COS(flow)) signals recorded at the airway opening is under debate. We hypothesized that these waves are originated from cyclic changes in pulmonary artery (PA) pressure and flow but not from the physical transmission of heartbeats onto the lungs. The aim of this study was to test this hypothesis. In 10 anesthetized pigs, COS were evaluated during expiratory breath-holds at baseline with intact chest and during open chest conditions at: (1) close contact between heart and lungs; (2) no heart-lungs contact by lifting the heart apex outside the thoracic cavity; (3) PA clamping at the main trunk during 10 s; and (4) during manual massage after cardiac arrest maintaining the heart apex outside the thorax, with and without PA clamping. Baseline COS(paw) and COS(flow) amplitude were 0.70 ± 0.08 cmH(2)O and 0.51 ± 0.06 L/min, respectively. Both COS amplitude decreased during open chest conditions in step 1 and 2 (p < 0.05). However, COS(paw) and COS(flow) amplitude did not depend on whether the heart was in contact or isolated from the surrounding lung parenchyma. COS(paw) and COS(flow) disappeared when pulmonary blood flow was stopped after clamping PA in all animals. Manual heart massages reproduced COS but they disappeared when PA was clamped during this maneuver. The transmission of PA pulsatilty across the lungs generates COS(paw) and COS(flow) measured at the airway opening. This information has potential applications for respiratory monitoring.
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Affiliation(s)
- Fernando Suarez-Sipmann
- Department of Surgical Sciences, Section of Anesthesiology & Critical Care, Uppsala University, Uppsala, Sweden.
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7
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Nieman G, Gatto L. Dynamic alveolar mechanics in acute lung injury. Crit Care Med 2010; 38:344-5; author reply 345. [DOI: 10.1097/ccm.0b013e3181bfe74f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Tusman G, Suarez-Sipmann F, Peces-Barba G, Climente C, Areta M, Arenas PG, Bohm SH. Pulmonary blood flow generates cardiogenic oscillations. Respir Physiol Neurobiol 2009; 167:247-54. [DOI: 10.1016/j.resp.2009.04.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 04/29/2009] [Accepted: 04/30/2009] [Indexed: 10/20/2022]
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9
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St Croix CM, Bauer EM. Use of spectral fluorescence resonance energy transfer to detect nitric oxide-based signaling events in isolated perfused lung. CURRENT PROTOCOLS IN CYTOMETRY 2008; Chapter 12:Unit12.13. [PMID: 18770645 DOI: 10.1002/0471142956.cy1213s45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Fluorescence resonance energy transfer (FRET) is a fluorescence microscopy technique suitable for live cells and capable of detecting changes in the conformational state of a single protein or the distance between two interacting proteins when the proteins are conjugated with appropriate donor and acceptor fluorophores. Confocal-based spectral detection systems enable the resolution of fluorescent images by providing full spectral information for each voxel of the image without switching of optical filters. Furthermore, using calibration spectra, it is possible to unambiguously separate the cross-talk between overlapping donor and acceptor emissions. This unit describes the use of confocal-based spectral imaging of nitric oxide (NO) sensitive FRET reporters in the vasculature of the intact, isolated perfused mouse lung. This type of in situ imaging approach allows the visualization and study of temporal molecular signaling events within the appropriate physiologic microenvironment of the intact, living organ.
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Affiliation(s)
- Claudette M St Croix
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania, USA
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10
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Robertson HT, Hlastala MP. Microsphere maps of regional blood flow and regional ventilation. J Appl Physiol (1985) 2006; 102:1265-72. [PMID: 17158248 DOI: 10.1152/japplphysiol.00756.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Systematically mapped samples cut from lungs previously labeled with intravascular and aerosol microspheres can be used to create high-resolution maps of regional perfusion and regional ventilation. With multiple radioactive or fluorescent microsphere labels available, this methodology can compare regional flow responses to different interventions without partial volume effects or registration errors that complicate interpretation of in vivo imaging measurements. Microsphere blood flow maps examined at different levels of spatial resolution have revealed that regional flow heterogeneity increases progressively down to an acinar level of scale. This pattern of scale-dependent heterogeneity is characteristic of a fractal distribution network, and it suggests that the anatomic configuration of the pulmonary vascular tree is the primary determinant of high-resolution regional flow heterogeneity. At approximately 2-cm(3) resolution, the large-scale gravitational gradients of blood flow per unit weight of alveolar tissue account for <5% of the overall flow heterogeneity. Furthermore, regional blood flow per gram of alveolar tissue remains relatively constant with different body positions, gravitational stresses, and exercise. Regional alveolar ventilation is accurately represented by the deposition of inhaled 1.0-microm fluorescent microsphere aerosols, at least down to the approximately 2-cm(3) level of scale. Analysis of these ventilation maps has revealed the same scale-dependent property of regional alveolar ventilation heterogeneity, with a strong correlation between ventilation and blood flow maintained at all levels of scale. The ventilation-perfusion (VA/Q) distributions obtained from microsphere flow maps of normal animals agree with simultaneously acquired multiple inert-gas elimination technique VA/Q distributions, but they underestimate gas-exchange impairment in diffuse lung injury.
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Affiliation(s)
- H Thomas Robertson
- Department of Medicine, University of Washingotn, Seattle, WA 98195-6522, USA.
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11
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Di Biase L, Fahmy TS, Wazni OM, Bai R, Patel D, Lakkireddy D, Cummings JE, Schweikert RA, Burkhardt JD, Elayi CS, Kanj M, Popova L, Prasad S, Martin DO, Prieto L, Saliba W, Tchou P, Arruda M, Natale A. Pulmonary vein total occlusion following catheter ablation for atrial fibrillation: clinical implications after long-term follow-up. J Am Coll Cardiol 2006; 48:2493-9. [PMID: 17174188 DOI: 10.1016/j.jacc.2006.08.038] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 08/01/2006] [Accepted: 08/08/2006] [Indexed: 02/07/2023]
Abstract
OBJECTIVES We present the clinical course and management outcomes of patients with total pulmonary vein occlusion (PVO). BACKGROUND Pulmonary vein occlusion is a rare complication that can develop after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The long term follow-up data of patients diagnosed with PVO are minimal. METHODS Data from 18 patients with complete occlusion of at least one pulmonary vein (PV) were prospectively collected. All patients underwent RFA for AF using different strategies between September 1999 and May 2004. Pulmonary vein occlusion was diagnosed using computed tomography (CT) and later confirmed by angiography when intervention was warranted. Lung perfusion scans were performed on all patients before and after intervention. The percent stenoses of the veins draining each independent lung were added together to yield an average cumulative stenosis of the vascular cross-sectional area draining the affected lung (cumulative stenosis index [CSI]). RESULTS The patients' symptoms had a positive correlation with the CSI (r = 0.843, p < 0.05) and a negative one with the lung perfusion (r = -0.667, p < 0.05). A CSI > or =75% correlated well with low lung perfusion (<25%; r = -0.854, p < 0.01). Patients with a CSI > or =75% appeared to improve mostly when early (r = -0.497) and repeat dilation/stenting (r = 0.0765) were performed. CONCLUSIONS Patients with single PVO are mostly asymptomatic and should undergo routine imaging. On the other hand, patients with concomitant ipsilateral PV stenosis/PVO and a CSI > or =75% require early and, when necessary, repeated pulmonary interventions for restoration of pulmonary flow and prevention of associated lung disease.
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Affiliation(s)
- Luigi Di Biase
- Department of Cardiovascular Medicine, Section of Cardiac Electrophysiology and Pacing, Cleveland Clinic, Cleveland, Ohio 44195, USA
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12
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van Heusden K, Gisolf J, Stok WJ, Dijkstra S, Karemaker JM. Mathematical modeling of gravitational effects on the circulation: importance of the time course of venous pooling and blood volume changes in the lungs. Am J Physiol Heart Circ Physiol 2006; 291:H2152-65. [PMID: 16632542 DOI: 10.1152/ajpheart.01268.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A dip in blood pressure (BP) in response to head-up tilt (HUT) or active standing might be due to rapid pooling in the veins below the heart (preload) or muscle activation-induced drop in systemic vascular resistance (afterload). We hypothesized that, in the cardiovascular response to passive HUT, where, in contrast to active standing, little BP dip is observed, features affecting the preload play a key role. We developed a baroreflex model combined with a lumped-parameter model of the circulation, including viscoelastic stress-relaxation of the systemic veins. Cardiac contraction is modeled using the varying-elastance concept. Gravity affects not only the systemic, but also the pulmonary, circulation. In accordance with the experimental results, model simulations do not show a BP dip on HUT; the tilt-back response is also realistic. If it is assumed that venous capacities are steady-state values, the introduction of stress-relaxation initially reduces venous pooling. The resulting time course of venous pooling is comparable to measured impedance changes. When venous pressure-volume dynamics are neglected, rapid (completed within 30 s) venous pooling leads to a drop in BP. The direct effect of gravity on the pulmonary circulation influences the BP response in the first ∼5 s after HUT and tilt back. In conclusion, the initial BP response to HUT is mainly determined by the response of the venous system. The time course of lower body pooling is essential in understanding the response to passive HUT.
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Affiliation(s)
- K van Heusden
- Dept. of Physiology, Rm. M01-216, Academic Medical Center, Univ. of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands
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13
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St Croix CM, Leelavanichkul K, Watkins SC. Intravital fluorescence microscopy in pulmonary research. Adv Drug Deliv Rev 2006; 58:834-40. [PMID: 16996641 DOI: 10.1016/j.addr.2006.07.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2006] [Revised: 06/02/2006] [Accepted: 07/13/2006] [Indexed: 11/29/2022]
Abstract
Over the last several years, microscopy as a scientific tool has reinvented itself evolving from a group of principally descriptive methodologies to encompass a wide range of primary tools and techniques to investigate the molecular organization of organs, tissues and cells. Advances in microscope and camera design, fluorescent dye technology, the development of fluorescent proteins as well as the advent of inexpensive powerful computers, has led to the feasibility of simultaneous sub micron resolution and quantitation of multiple concurrent molecular markers for both protein and DNA. Confocal microscopy has allowed optical sectioning and reconstruction of tissues in three dimensions. Finally, the development of multiphoton methodologies as an extension of optical sectioning microscopy has further improved the potential utility of this technology when examining living or light scattering tissues such as the lung. In order to illustrate the utility of two-photon methods in pulmonary biology, we present the application of this approach to the study of cellular trafficking in situ and to the study of pulmonary vasoregulation in an ex vivo rodent model.
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Affiliation(s)
- Claudette M St Croix
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA 15219, USA.
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14
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Waisman D, Abramovich A, Brod V, Lavon O, Nurkin S, Popovski F, Rotschild A, Bitterman H. Subpleural microvascular flow velocities and shear rates in normal and septic mechanically ventilated rats. Shock 2006; 26:87-94. [PMID: 16783203 DOI: 10.1097/01.shk.0000215317.22113.b2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Changes in pulmonary microhemodynamics are important variables in a large variety of pathological processes. We used in vivo fluorescent videomicroscopy of the subpleural microvasculature in mechanically ventilated rats to directly monitor microvascular flow velocity (FV) and shear rate in pulmonary arterioles, capillaries, and venules in healthy rats and in septic rats 20 h after cecal ligation and puncture (CLP). Observations were made through a small thoracotomy after injection of fluorescent microspheres (D = 1 microm) into the systemic circulation. The FVs were calculated off-line by frame-by-frame measurements of the distance covered by individual microspheres per unit of time. In healthy rats, inspiratory FV were 1322 +/- 142 microm/s in subpleural arterioles and 599 +/- 25 microm/s in capillaries. The highest FV was found in venules (1552 +/- 132 microm/s). The calculated shear rates were 547 +/- 62/s in arterioles and 619 +/- 19/s in capillaries. The highest shear rates were detected in venules (677 +/- 59/s). No significant changes in FV and shear rates were observed throughout the 1-h observation period in any of the microvascular compartments. Pulmonary microvascular FV and shear rates found in sham-operated rats in the CLP experiments were not significantly different from values of healthy rats. The CLP caused a significant increase in leukocyte sequestration in the lungs and a mean of 27% to 34% decrease in FV in all sections of the pulmonary microvasculature (P < 0.001 in capillaries and P < 0.05 in venules). Also, CLP caused a 23% decrease in capillary shear rate that reached only borderline statistical significance (P < 0.06) and a significant 35% decrease in mean shear rate in venules (P < 0.05). Fluorescent videomicroscopy is offered as a stable and reproducible method for in vivo determinations of pulmonary microhemodynamics in clinically relevant models of sepsis.
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Affiliation(s)
- Dan Waisman
- Ischemia-Shock Research Laboratory, Carmel Medical Center, The Bruce and Ruth Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 34362, Israel
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15
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López-Aguilar J, Piacentini E, Villagrá A, Murias G, Pascotto S, Saenz-Valiente A, Fernández-Segoviano P, Hotchkiss JR, Blanch L. Contributions of vascular flow and pulmonary capillary pressure to ventilator-induced lung injury. Crit Care Med 2006; 34:1106-12. [PMID: 16484897 DOI: 10.1097/01.ccm.0000205757.66971.da] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the influence of vascular flow on ventilator-induced lung injury independent of vascular pressures. DESIGN Laboratory study. SETTING Hospital laboratory. SUBJECTS Thirty-two New Zealand White rabbits. INTERVENTIONS Thirty-two isolated perfused rabbit lungs were allocated into four groups: low flow/low pulmonary capillary pressure; high flow/high pulmonary capillary pressure; low flow/high pulmonary capillary pressure, and high flow/low pulmonary capillary pressure. All lungs were ventilated with peak airway pressure 30 cm H2O and positive end-expiratory pressure 5 cm H2O for 30 mins. MEASUREMENTS AND MAIN RESULTS Outcome measures included frequency of gross structural failure (pulmonary rupture), pulmonary hemorrhage, edema formation, changes in lung compliance, pulmonary vascular resistance, and pulmonary ultrafiltration coefficient. Lungs exposed to high pulmonary vascular flow ruptured more frequently, displayed more hemorrhage, developed more edema, suffered larger decreases in compliance, and had larger increases in vascular resistance than lungs exposed to low vascular flows (p < .05 for each pairwise comparison between groups). CONCLUSIONS These findings suggest that high pulmonary vascular flows might exacerbate ventilator-induced lung injury independent of their effects on pulmonary vascular pressures.
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Affiliation(s)
- Josefina López-Aguilar
- Critical Care Center, Hospital de Sabadell, Institut Universitari Parc Taulí, Universitat Autónoma de Barcelona, Esfera UAB, Spain
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16
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Lawler C, Suk WA, Pitt BR, Croix CMS, Watkins SC. Multimodal optical imaging. Am J Physiol Lung Cell Mol Physiol 2003; 285:L269-80. [PMID: 12851207 DOI: 10.1152/ajplung.00424.2002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The recent resurgence of interest in the use of intravital microscopy in lung research is a manifestation of extraordinary progress in visual imaging and optical microscopy. This review evaluates the tools and instrumentation available for a number of imaging modalities, with particular attention to recent technological advances, and addresses recent progress in use of optical imaging techniques in basic pulmonary research.1 Limitations of existing methods and anticipated future developments are also identified. Although there have also been major advances made in the use of magnetic resonance imaging, positron emission tomography, and X-ray and computed tomography to image intact lungs and while these technologies have been instrumental in advancing the diagnosis and treatment of patients, the purpose of this review is to outline developing optical methods that can be evaluated for use in basic research in pulmonary biology.
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Affiliation(s)
- Cindy Lawler
- National Institute of Environmental Health Sciences, Research Traingle Park, North Carolina 27709, USA
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Baumgartner WA, Jaryszak EM, Peterson AJ, Presson RG, Wagner WW. Heterogeneous capillary recruitment among adjoining alveoli. J Appl Physiol (1985) 2003; 95:469-76. [PMID: 12851416 DOI: 10.1152/japplphysiol.01115.2002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pulmonary capillaries recruit when microvascular pressure is raised. The details of the relationship between recruitment and pressure, however, are controversial. There are data supporting 1). gradual homogeneous recruitment, 2). sudden and complete recruitment, and 3). heterogeneous recruitment. The present study was designed to determine whether alveolar capillary networks recruit in a variety of ways or whether one model predominates. In isolated, pump-perfused canine lung lobes, fields of six neighboring alveoli were recorded with video microscopy as pulmonary venous pressure was raised from 0 to 40 mmHg in 5-mmHg increments. The largest group of alveoli (42%) recruited gradually. Another group (33%) recruited suddenly (sheet flow). Half of the neighborhoods had at least one alveolus that paradoxically derecruited when pressure was increased, even though neighboring alveoli continued to recruit capillaries. At pulmonary venous pressures of 40 mmHg, 86% of the alveolar-capillary networks were not fully recruited. We conclude that the pattern of recruitment among neighboring alveoli is complex, is not homogeneous, and may not reach full recruitment, even under extreme pressures.
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Affiliation(s)
- William A Baumgartner
- Department of Anesthesis, Indiana University School of Medicine, Indianapolis, IN 46202-5120, USA
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Presson RG, Baumgartner WA, Peterson AJ, Glenny RW, Wagner WW. Pulmonary capillaries are recruited during pulsatile flow. J Appl Physiol (1985) 2002; 92:1183-90. [PMID: 11842057 DOI: 10.1152/japplphysiol.00845.2001] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Capillaries recruit when pulmonary arterial pressure rises. The duration of increased pressure imposed in such experiments is usually on the order of minutes, although recent work shows that the recruitment response can occur in <4 s. In the present study, we investigate whether the brief pressure rise during cardiac systole can also cause recruitment and whether the recruitment is maintained during diastole. To study these basic aspects of pulmonary capillary hemodynamics, isolated dog lungs were pump perfused alternately by steady flow and pulsatile flow with the mean arterial and left atrial pressures held constant. Several direct measurements of capillary recruitment were made with videomicroscopy. The total number and total length of perfused capillaries increased significantly during pulsatile flow by 94 and 105%, respectively. Of the newly recruited capillaries, 92% were perfused by red blood cells throughout the pulsatile cycle. These data provide the first direct account of how the pulmonary capillaries respond to pulsatile flow by showing that capillaries are recruited during the systolic pulse and that, once open, the capillaries remain open throughout the pulsatile cycle.
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Affiliation(s)
- Robert G Presson
- Department of Anesthesiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5200, USA.
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Glenny RW, Lamm WJ, Bernard SL, An D, Chornuk M, Pool SL, Wagner WW, Hlastala MP, Robertson HT. Selected contribution: redistribution of pulmonary perfusion during weightlessness and increased gravity. J Appl Physiol (1985) 2000; 89:1239-48. [PMID: 10956375 DOI: 10.1152/jappl.2000.89.3.1239] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To compare the relative contributions of gravity and vascular structure to the distribution of pulmonary blood flow, we flew with pigs on the National Aeronautics and Space Administration KC-135 aircraft. A series of parabolas created alternating weightlessness and 1.8-G conditions. Fluorescent microspheres of varying colors were injected into the pulmonary circulation to mark regional blood flow during different postural and gravitational conditions. The lungs were subsequently removed, air dried, and sectioned into approximately 2 cm(3) pieces. Flow to each piece was determined for the different conditions. Perfusion heterogeneity did not change significantly during weightlessness compared with normal and increased gravitational forces. Regional blood flow to each lung piece changed little despite alterations in posture and gravitational forces. With the use of multiple stepwise linear regression, the contributions of gravity and vascular structure to regional perfusion were separated. We conclude that both gravity and the geometry of the pulmonary vascular tree influence regional pulmonary blood flow. However, the structure of the vascular tree is the primary determinant of regional perfusion in these animals.
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Affiliation(s)
- R W Glenny
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington 98195, USA.
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