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Bachmann KF, Moller PW, Hunziker L, Maggiorini M, Berger D. Mechanisms maintaining right ventricular contractility-to-pulmonary arterial elastance ratio in VA ECMO: a retrospective animal data analysis of RV-PA coupling. J Intensive Care 2024; 12:19. [PMID: 38734616 PMCID: PMC11088130 DOI: 10.1186/s40560-024-00730-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 04/14/2024] [Indexed: 05/13/2024] Open
Abstract
BACKGROUND To optimize right ventricular-pulmonary coupling during veno-arterial (VA) ECMO weaning, inotropes, vasopressors and/or vasodilators are used to change right ventricular (RV) function (contractility) and pulmonary artery (PA) elastance (afterload). RV-PA coupling is the ratio between right ventricular contractility and pulmonary vascular elastance and as such, is a measure of optimized crosstalk between ventricle and vasculature. Little is known about the physiology of RV-PA coupling during VA ECMO. This study describes adaptive mechanisms for maintaining RV-PA coupling resulting from changing pre- and afterload conditions in VA ECMO. METHODS In 13 pigs, extracorporeal flow was reduced from 4 to 1 L/min at baseline and increased afterload (pulmonary embolism and hypoxic vasoconstriction). Pressure and flow signals estimated right ventricular end-systolic elastance and pulmonary arterial elastance. Linear mixed-effect models estimated the association between conditions and elastance. RESULTS At no extracorporeal flow, end-systolic elastance increased from 0.83 [0.66 to 1.00] mmHg/mL at baseline by 0.44 [0.29 to 0.59] mmHg/mL with pulmonary embolism and by 1.36 [1.21 to 1.51] mmHg/mL with hypoxic pulmonary vasoconstriction (p < 0.001). Pulmonary arterial elastance increased from 0.39 [0.30 to 0.49] mmHg/mL at baseline by 0.36 [0.27 to 0.44] mmHg/mL with pulmonary embolism and by 0.75 [0.67 to 0.84] mmHg/mL with hypoxic pulmonary vasoconstriction (p < 0.001). Coupling remained unchanged (2.1 [1.8 to 2.3] mmHg/mL at baseline; - 0.1 [- 0.3 to 0.1] mmHg/mL increase with pulmonary embolism; - 0.2 [- 0.4 to 0.0] mmHg/mL with hypoxic pulmonary vasoconstriction, p > 0.05). Extracorporeal flow did not change coupling (0.0 [- 0.0 to 0.1] per change of 1 L/min, p > 0.05). End-diastolic volume increased with decreasing extracorporeal flow (7.2 [6.6 to 7.8] ml change per 1 L/min, p < 0.001). CONCLUSIONS The right ventricle dilates with increased preload and increases its contractility in response to afterload changes to maintain ventricular-arterial coupling during VA extracorporeal membrane oxygenation.
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Affiliation(s)
- Kaspar F Bachmann
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
| | - Per Werner Moller
- Department of Anesthesia, SV Hospital Group, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lukas Hunziker
- Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Maggiorini
- Medical Intensive Care Unit, University Hospital Zürich, University of Zürich, Zurich, Switzerland
| | - David Berger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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2
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Lim HS. Phenotyping and Hemodynamic Assessment in Cardiogenic Shock: From Physiology to Clinical Application. Cardiol Ther 2022; 11:509-522. [PMID: 36335176 PMCID: PMC9652191 DOI: 10.1007/s40119-022-00286-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 10/18/2022] [Indexed: 11/08/2022] Open
Abstract
There is growing interest in invasive hemodynamic assessment in cardiogenic shock, primarily due to the widespread adoption of mechanical circulatory support (MCS). Invasive hemodynamic assessment is central to two aspects of cardiogenic shock management: (1) the phenotyping of cardiogenic shock, and (2) the assessment of response to therapy. Phenotyping of cardiogenic shock serves to guide timely therapeutic intervention, and the assessment of hemodynamic response to therapy directs the escalation or de-escalation of therapy, including MCS. This review aims to discuss these two aspects of hemodynamic assessment in cardiogenic shock. Firstly, the physiologic underpinnings of a phenotyping schema, and the implication of the cardiogenic shock phenotype on the MCS strategy in cardiogenic shock will be discussed. Secondly, the concept of cardiac power output and 'effective' oxygen delivery will be discussed in relation to hemodynamic response to therapy in cardiogenic shock.
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Affiliation(s)
- Hoong Sern Lim
- Queen Elizabeth Hospital Birmingham, University Hospitals Birmingham NHS Foundation Trust, Edgbaston, Birmingham, B15 2TH, UK.
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3
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Naeije R, Richter MJ, Rubin LJ. The physiologic basis of pulmonary arterial hypertension. Eur Respir J 2021; 59:13993003.02334-2021. [PMID: 34737219 PMCID: PMC9203839 DOI: 10.1183/13993003.02334-2021] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/18/2021] [Indexed: 11/05/2022]
Abstract
Pulmonary arterial hypertension (PAH) is a rare dyspnea-fatigue syndrome caused by a progressive increase in pulmonary vascular resistance (PVR) and eventual right ventricular (RV) failure. In spite of extensive pulmonary vascular remodeling, lung function in PAH is generally well preserved, with hyperventilation and increased physiologic dead space, but minimal changes in lung mechanics and only mild to moderate hypoxemia and hypocapnia. Hypoxemia is mainly caused by a low mixed venous PO2 from a decreased cardiac output. Hypocapnia is mainly caused by an increased chemosensitivity. Exercise limitation in PAH is cardiovascular rather than ventilatory or muscular. The extent of pulmonary vascular disease in PAH is defined by multipoint pulmonary vascular pressure-flow relationships with a correction for hematocrit. Pulsatile pulmonary vascular pressure-flow relationships in PAH allow for the assessment of RV hydraulic load. This analysis is possible either in the frequency-domain or in the time-domain. The RV in PAH adapts to increased afterload by an increased contractility to preserve its coupling to the pulmonary circulation. When this homeometric mechanism is exhausted, the RV dilates to preserve flow output by an additional heterometric mechanism. Right heart failure is then diagnosed by imaging of increased right heart dimensions and clinical systemic congestion signs and symptoms. The coupling of the RV to the pulmonary circulation is assessed by the ratio of end-systolic to arterial elastances, but these measurements are difficult. Simplified estimates of RV-PA coupling can be obtained by magnetic resonance or echocardiographic imaging of ejection fraction.
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Affiliation(s)
| | - Manuel J Richter
- Department of Internal Medicine, Justus Liebig-University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
| | - Lewis J Rubin
- University of California, San Diego, La Jolla, CA, USA
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4
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Liu S, Moller PW, Kohler A, Hana A, Beldi G, Obrist D, Berger D, Takala J, Jakob SM. Effects of Trendelenburg position and increased airway pressure on hepatic regional blood flow of normal and resected liver. J Appl Physiol (1985) 2020; 128:667-680. [DOI: 10.1152/japplphysiol.00705.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
High portal venous blood flow (Qpv) may contribute to posthepatectomy liver failure. Both Trendelenburg position (TP) and elevated airway pressure (Paw) increase backpressure to venous return and may thereby reduce Qpv. The aim of this study was to evaluate the effects of TP and increased Paw on hepatosplanchnic hemodynamics before and after major liver resection. Arterial and venous blood pressures, Qpv, extrasplanchnic inferior vena cava (Qivc), superior mesenteric (Qsma), hepatic (Qha), and carotid artery blood flows (Qca) were measured in 14 anesthetized and mechanically ventilated pigs in supine and 30° TP during end-expiratory hold at 5 cmH2O positive end-expiratory pressure (PEEP) and during inspiratory hold with Paw of 15, 20, 25, and 30 cmH2O. After major liver resection, the interventions were repeated in seven randomly selected animals. At baseline, TP increased right atrial pressure (Pra) and Qpv but not Qivc or Qsma. With increased Paw in the supine position, Pra increased and all regional blood flows decreased. TP during increasing Paw attenuated the decrease in Qpv, Qsma, and Qivc but not in Qha or Qca. After liver resection, the effects of TP during increasing Paw remained, albeit at higher portal vein pressures. However, TP alone did not increase IVC venous return. Increasing Paw in supine position reduces Qpv and all other regional flows, while the reduction in Qpv is attenuated in TP, suggesting partly preserved liver waterfall or decreased intrahepatic resistance. Liver resection, despite resulting in major intrahepatic blood flow changes, does not fundamentally influence the interaction of increasing Paw and TP on regional perfusion. NEW & NOTEWORTHY In Trendelenburg position (TP), liver blood flow is the only contributor to increased venous return measured in the inferior vena cava (IVC), which attenuates the decreased IVC venous return induced by increasing airway pressure. After liver resection, TP similarly attenuated effects of increasing airway pressure.
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Affiliation(s)
- Shengchen Liu
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Per W. Moller
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Anesthesiology and Intensive Care Medicine, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital Ostra, Gothenburg, Sweden
| | - Andreas Kohler
- Department of Visceral Surgery and Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Anisa Hana
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Guido Beldi
- Department of Visceral Surgery and Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - David Berger
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Jukka Takala
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stephan M. Jakob
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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5
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Philip JL, Tabima DM, Wolf GD, Frump AL, Cheng TC, Schreier DA, Hacker TA, Lahm T, Chesler NC. Exogenous Estrogen Preserves Distal Pulmonary Arterial Mechanics and Prevents Pulmonary Hypertension in Rats. Am J Respir Crit Care Med 2020; 201:371-374. [PMID: 31661294 PMCID: PMC6999110 DOI: 10.1164/rccm.201906-1217le] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Jennifer L. Philip
- University of Wisconsin–Madison
College of EngineeringMadison, Wisconsin
- University of Wisconsin–Madison
School of Medicine and Public HealthMadison, Wisconsin
| | - Diana M. Tabima
- University of Wisconsin–Madison
College of EngineeringMadison, Wisconsin
| | - Gregory D. Wolf
- University of Wisconsin–Madison
College of EngineeringMadison, Wisconsin
| | - Andrea L. Frump
- Indiana University School of
MedicineIndianapolis, Indianaand
| | - Tik-Chee Cheng
- University of Wisconsin–Madison
College of EngineeringMadison, Wisconsin
| | - David A. Schreier
- University of Wisconsin–Madison
College of EngineeringMadison, Wisconsin
| | - Timothy A. Hacker
- University of Wisconsin–Madison
School of Medicine and Public HealthMadison, Wisconsin
| | - Tim Lahm
- Indiana University School of
MedicineIndianapolis, Indianaand
- Richard L. Roudebush VA Medical
CenterIndianapolis, Indiana
| | - Naomi C. Chesler
- University of Wisconsin–Madison
College of EngineeringMadison, Wisconsin
- University of Wisconsin–Madison
School of Medicine and Public HealthMadison, Wisconsin
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6
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Vanden Eynden F, Segers P, Bové T, De Somer F, El Oumeiri B, Van Nooten G. Use of a right ventricular continuous flow pump to validate the distensible model of the pulmonary vasculature. Physiol Res 2019; 68:233-243. [PMID: 30628823 DOI: 10.33549/physiolres.933894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In the pulmonary circulation, resistive and compliant properties overlap in the same vessels. Resistance varies nonlinearly with pressure and flow; this relationship is driven by the elastic properties of the vessels. Linehan et al. correlated the mean pulmonary arterial pressure and mean flow with resistance using an original equation incorporating the distensibility of the pulmonary arteries. The goal of this study was to validate this equation in an in vivo porcine model. In vivo measurements were acquired in 6 pigs. The distensibility coefficient (DC) was measured by placing piezo-electric crystals around the pulmonary artery (PA). In addition to experiments under pulsatile conditions, a right ventricular (RV) bypass system was used to induce a continuous pulmonary flow state. The Linehan et al. equation was then used to predict the pressure from the flow under continuous flow conditions. The diameter-derived DC was 2.4%/mmHg (+/-0.4%), whereas the surface area-based DC was 4.1 %/mmHg (+/-0.1%). An increase in continuous flow was associated with a constant decrease in resistance, which correlated with the diameter-based DC (r=-0.8407, p=0.044) and the surface area-based DC (r=-0.8986, p=0.028). In contrast to the Linehan et al. equation, our results showed constant or even decreasing pressure as flow increased. Using a model of continuous pulmonary flow induced by an RV assist system, pulmonary pressure could not be predicted based on the flow using the Linehan et al. equation. Measurements of distensibility based on the diameter of the PA were inversely correlated with the resistance.
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Affiliation(s)
- F Vanden Eynden
- Department of Cardiac Surgery, Université Libre de Bruxelles, Hopital Académique, Erasme, Brussels, Belgium.
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7
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Philip JL, Murphy TM, Schreier DA, Stevens S, Tabima DM, Albrecht M, Frump AL, Hacker TA, Lahm T, Chesler NC. Pulmonary vascular mechanical consequences of ischemic heart failure and implications for right ventricular function. Am J Physiol Heart Circ Physiol 2019; 316:H1167-H1177. [PMID: 30767670 DOI: 10.1152/ajpheart.00319.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Left heart failure (LHF) is the most common cause of pulmonary hypertension, which confers an increase in morbidity and mortality in this context. Pulmonary vascular resistance has prognostic value in LHF, but otherwise the mechanical consequences of LHF for the pulmonary vasculature and right ventricle (RV) remain unknown. We sought to investigate mechanical mechanisms of pulmonary vascular and RV dysfunction in a rodent model of LHF to address the knowledge gaps in understanding disease pathophysiology. LHF was created using a left anterior descending artery ligation to cause myocardial infarction (MI) in mice. Sham animals underwent thoracotomy alone. Echocardiography demonstrated increased left ventricle (LV) volumes and decreased ejection fraction at 4 wk post-MI that did not normalize by 12 wk post-MI. Elevation of LV diastolic pressure and RV systolic pressure at 12 wk post-MI demonstrated pulmonary hypertension (PH) due to LHF. There was increased pulmonary arterial elastance and pulmonary vascular resistance associated with perivascular fibrosis without other remodeling. There was also RV contractile dysfunction with a 35% decrease in RV end-systolic elastance and 66% decrease in ventricular-vascular coupling. In this model of PH due to LHF with reduced ejection fraction, pulmonary fibrosis contributes to increased RV afterload, and loss of RV contractility contributes to RV dysfunction. These are key pathologic features of human PH secondary to LHF. In the future, novel therapeutic strategies aimed at preventing pulmonary vascular mechanical changes and RV dysfunction in the context of LHF can be tested using this model. NEW & NOTEWORTHY In this study, we investigate the mechanical consequences of left heart failure with reduced ejection fraction for the pulmonary vasculature and right ventricle. Using comprehensive functional analyses of the cardiopulmonary system in vivo and ex vivo, we demonstrate that pulmonary fibrosis contributes to increased RV afterload and loss of RV contractility contributes to RV dysfunction. Thus this model recapitulates key pathologic features of human pulmonary hypertension-left heart failure and offers a robust platform for future investigations.
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Affiliation(s)
- Jennifer L Philip
- Department of Biomedical Engineering, University of Wisconsin-Madison College of Engineering , Madison, Wisconsin.,Department of Surgery, University of Wisconsin-Madison , Madison, Wisconsin
| | - Thomas M Murphy
- Department of Biomedical Engineering, University of Wisconsin-Madison College of Engineering , Madison, Wisconsin
| | - David A Schreier
- Department of Biomedical Engineering, University of Wisconsin-Madison College of Engineering , Madison, Wisconsin
| | - Sydney Stevens
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana
| | - Diana M Tabima
- Department of Biomedical Engineering, University of Wisconsin-Madison College of Engineering , Madison, Wisconsin
| | - Margie Albrecht
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana
| | - Andrea L Frump
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana
| | - Timothy A Hacker
- Department of Medicine, University of Wisconsin-Madison , Madison, Wisconsin
| | - Tim Lahm
- Department of Medicine, Indiana University School of Medicine , Indianapolis, Indiana.,Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana.,Richard L. Roudebush Veterans Affairs Medical Center , Indianapolis, Indiana
| | - Naomi C Chesler
- Department of Biomedical Engineering, University of Wisconsin-Madison College of Engineering , Madison, Wisconsin.,Department of Medicine, University of Wisconsin-Madison , Madison, Wisconsin
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8
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Brito J, Siques P, López R, Romero R, León-Velarde F, Flores K, Lüneburg N, Hannemann J, Böger RH. Long-Term Intermittent Work at High Altitude: Right Heart Functional and Morphological Status and Associated Cardiometabolic Factors. Front Physiol 2018; 9:248. [PMID: 29623044 PMCID: PMC5874329 DOI: 10.3389/fphys.2018.00248] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/06/2018] [Indexed: 12/14/2022] Open
Abstract
Background: Living at high altitude or with chronic hypoxia implies functional and morphological changes in the right ventricle and pulmonary vasculature with a 10% prevalence of high-altitude pulmonary hypertension (HAPH). The implications of working intermittently (day shifts) at high altitude (hypobaric hypoxia) over the long term are still not well-defined. The aim of this study was to evaluate the right cardiac circuit status along with potentially contributory metabolic variables and distinctive responses after long exposure to the latter condition. Methods: A cross-sectional study of 120 healthy miners working at an altitude of 4,400-4,800 m for over 5 years in 7-day commuting shifts was designed. Echocardiography was performed on day 2 at sea level. Additionally, biomedical and biochemical variables, Lake Louise scores (LLSs), sleep disturbances and physiological variables were measured at altitude and at sea level. Results: The population was 41.8 ± 0.7 years old, with an average of 14 ± 0.5 (range 5-29) years spent at altitude. Most subjects still suffered from mild to moderate symptoms of acute mountain sickness (mild was an LLS of 3-5 points, including cephalea; moderate was LLS of 6-10 points) (38.3%) at the end of day 1 of the shift. Echocardiography showed a 23% mean pulmonary artery pressure (mPAP) >25 mmHg, 9% HAPH (≥30 mmHg), 85% mild increase in right ventricle wall thickness (≥5 mm), 64% mild right ventricle dilation, low pulmonary vascular resistance (PVR) and fairly good ventricle performance. Asymmetric dimethylarginine (ADMA) (OR 8.84 (1.18-66.39); p < 0.05) and insulin (OR: 1.11 (1.02-1.20); p < 0.05) were associated with elevated mPAP and were defined as a cut-off. Interestingly, the correspondence analysis identified association patterns of several other variables (metabolic, labor, and biomedical) with higher mPAP. Conclusions: Working intermittently at high altitude involves a distinctive pattern. The most relevant and novel characteristics are a greater prevalence of elevated mPAP and HAPH than previously reported at chronic intermittent hypobaric hypoxia (CIHH), which is accompanied by subsequent morphological characteristics. These findings are associated with cardiometabolic factors (insulin and ADMA). However, the functional repercussions seem to be minor or negligible. This research contributes to our understanding and surveillance of this unique model of chronic intermittent high-altitude exposure.
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Affiliation(s)
- Julio Brito
- Institute of Health Studies, University Arturo Prat, Iquique, Chile
| | - Patricia Siques
- Institute of Health Studies, University Arturo Prat, Iquique, Chile
| | - Rosario López
- Department of Preventive Medicine and Public Health, University Autonoma of Madrid, Madrid, Spain
| | - Raul Romero
- Institute of Health Studies, University Arturo Prat, Iquique, Chile
| | - Fabiola León-Velarde
- Department of Biological and Physiological Sciences, Facultad de Ciencias y Filosofía/IIA, University Peruana Cayetano Heredia, Lima, Peru
| | - Karen Flores
- Institute of Health Studies, University Arturo Prat, Iquique, Chile
| | - Nicole Lüneburg
- Institute of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Juliane Hannemann
- Institute of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Rainer H Böger
- Institute of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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9
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Guazzi M, Labate V. Pulmonary Hypertension in Heart Failure Patients: Pathophysiology and Prognostic Implications. Curr Heart Fail Rep 2017; 13:281-294. [PMID: 27858232 DOI: 10.1007/s11897-016-0306-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Pulmonary hypertension (PH) due to left heart disease (LHD), i.e., group 2 PH, is the most common reason for increased pressures in the pulmonary circuit. Although recent guidelines incorporate congenital heart disease in this classification, left-sided heart diseases of diastolic and systolic origin including valvular etiology are the vast majority. In these patients, an increased left-sided filling pressure triggers a multistage hemodynamic evolution that ends into right ventricular failure through an initial passive increase in pulmonary artery pressure complicated over time by pulmonary vasoconstriction, endothelial dysfunction, and remodeling of the small-resistance pulmonary arteries. Regardless of the underlying left heart pathology, when present, PH-LHD is associated with more severe symptoms, worse exercise tolerance, and outcome, especially when right ventricular dysfunction and failure are part of the picture. Compared with group 1 and other forms of pulmonary arterial hypertension, PH-LHD is more often seen in elderly patients with a higher prevalence of cardiovascular comorbidities and most, if not all, of the features of metabolic syndrome, especially in case of HF preserved ejection fraction. In this review, we provide an update on current knowledge and some potential challenges about the pathophysiology and established prognostic implications of group 2 PH in patients with HF of either preserved or reduced ejection fraction.
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Affiliation(s)
- Marco Guazzi
- University Cardiology Department, IRCCS Policlinico San Donato, University of Milano, Piazza Malan, 2, 20097, Milan, Italy.
| | - Valentina Labate
- University Cardiology Department, IRCCS Policlinico San Donato, University of Milano, Piazza Malan, 2, 20097, Milan, Italy
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10
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Shigemi K, Fuke S, Une D, Saku K, Shimizu S, Kawada T, Shishido T, Sunagawa K, Sugimachi M. Physiological insights of recent clinical diagnostic and therapeutic technologies for cardiovascular diseases. J Physiol Sci 2017; 67:655-672. [PMID: 28681363 PMCID: PMC5698391 DOI: 10.1007/s12576-017-0554-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 06/22/2017] [Indexed: 12/21/2022]
Abstract
Diagnostic and therapeutic methods for cardiovascular diseases continue to be developed in the 21st century. Clinicians should consider the physiological characteristics of the cardiovascular system to ensure successful diagnosis and treatment. In this review, we focus on the roles of cardiovascular physiology in recent diagnostic and therapeutic technologies for cardiovascular diseases. In the first section, we discuss how to evaluate and utilize left ventricular arterial coupling in the clinical settings. In the second section, we review unique characteristics of pulmonary circulation in the diagnosis and treatment of pulmonary hypertension. In the third section, we discuss physiological and anatomical factors associated with graft patency after coronary artery bypass grafting. In the last section, we discuss the usefulness of mechanical ventricular unloading after acute myocardial infarction. Clinical development of diagnostic methods and therapies for cardiovascular diseases should be based on physiological insights of the cardiovascular system.
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Affiliation(s)
- Kenji Shigemi
- Department of Anesthesiology and Reanimatology, University of Fukui Faculty of Medical Sciences, Fukui, Japan
| | - Soichiro Fuke
- Department of Cardiology, Japanese Red Cross Okayama Hospital, Okayama, Japan
| | - Dai Une
- Division of Cardiovascular Surgery, Yamato Seiwa Hospital, Yamato, Kanagawa, Japan
| | - Keita Saku
- Department of Therapeutic Regulation of Cardiovascular Homeostasis, Center for Disruptive Cardiovascular Medicine, Kyushu University, Fukuoka, Japan
| | - Shuji Shimizu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565, Japan.
| | - Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565, Japan
| | - Toshiaki Shishido
- Department of Research Promotion, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Kenji Sunagawa
- Department of Therapeutic Regulation of Cardiovascular Homeostasis, Center for Disruptive Cardiovascular Medicine, Kyushu University, Fukuoka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565, Japan
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11
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Ploegstra MJ, Brokelman JGM, Roos-Hesselink JW, Douwes JM, van Osch-Gevers LM, Hoendermis ES, van den Bosch AE, Witsenburg M, Bartelds B, Hillege HL, Berger RMF. Pulmonary arterial stiffness indices assessed by intravascular ultrasound in children with early pulmonary vascular disease: prediction of advanced disease and mortality during 20-year follow-up. Eur Heart J Cardiovasc Imaging 2017; 19:216-224. [DOI: 10.1093/ehjci/jex015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 01/27/2017] [Indexed: 01/26/2023] Open
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12
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The Effect of Left Ventricular Assist Device Therapy in Patients with Heart Failure and Mixed Pulmonary Hypertension. Int J Artif Organs 2017; 40:67-73. [DOI: 10.5301/ijao.5000556] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2017] [Indexed: 11/20/2022]
Abstract
Background Diastolic pressure gradient (DPG) of ≥7 mmHg has been proposed to distinguish mixed pulmonary hypertension from isolated post-capillary pulmonary hypertension in heart failure (HF). We evaluated the changes in pulmonary hemodynamics with left ventricular assist devices (LVADs) in patients with DPG of ≥7 or <7 mmHg, and effects on peak oxygen uptake (VO2) in patients with advanced HF. Methods Pre- and post-LVAD implant pulmonary hemodynamics (including right atrial (RA) pressures, DPG, pulmonary vascular resistance (PVR), pulmonary capacitance (PCap) and cardiac output), echocardiography, cardiopulmonary exercise test were measured in 38 consecutive patients. Results Ten of 38 patients had baseline DPG ≥7 mmHg. There were no significant difference in baseline characteristics, peak VO2 and ventilation slope, but PVR were higher, and PCap lower in patients with DPG ≥7 mmHg. Pulmonary artery pressures improved in all patients, but PVR and DPG remained higher and PCap lower in patients with baseline DPG ≥7 mmHg after a median follow-up of 181 (IQR 153–193) days. Peak VO2 increased and ventilation slope reduced post-LVAD, and these improvements were comparable between groups. Only RA pressure reduction and exercise increase in heart rate were significant predictors of peak VO2 increase on multivariate analysis. Conclusions Baseline DPG of ≥7 mmHg compared to DPG <7 mmHg have persistently lower PCap and higher PVR post-LVAD, but the increase in peak VO2 was comparable despite these residual pulmonary vascular abnormalities. The improvement in peak VO2 was related to reduction in right atrial pressure and exercise increase in heart rate.
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Assad TR, Brittain EL, Wells QS, Farber-Eger EH, Halliday SJ, Doss LN, Xu M, Wang L, Harrell FE, Yu C, Robbins IM, Newman JH, Hemnes AR. Hemodynamic evidence of vascular remodeling in combined post- and precapillary pulmonary hypertension. Pulm Circ 2016; 6:313-21. [PMID: 27683608 PMCID: PMC5019084 DOI: 10.1086/688516] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/28/2016] [Indexed: 01/06/2023] Open
Abstract
Although commonly encountered, patients with combined postcapillary and precapillary pulmonary hypertension (Cpc-PH) have poorly understood pulmonary vascular properties. The product of pulmonary vascular resistance and compliance, resistance-compliance (RC) time, is a measure of pulmonary vascular physiology. While RC time is lower in postcapillary PH than in precapillary PH, the RC time in Cpc-PH and the effect of pulmonary wedge pressure (PWP) on RC time are unknown. We tested the hypothesis that Cpc-PH has an RC time that resembles that in pulmonary arterial hypertension (PAH) more than that in isolated postcapillary PH (Ipc-PH). We analyzed the hemodynamics of 282 consecutive patients with PH referred for right heart catheterization (RHC) with a fluid challenge from 2004 to 2013 (cohort A) and 4,382 patients who underwent RHC between 1998 and 2014 for validation (cohort B). Baseline RC time in Cpc-PH was higher than that in Ipc-PH and lower than that in PAH in both cohorts (P < 0.001). In cohort A, RC time decreased after fluid challenge in patients with Ipc-PH but not in those with PAH or Cpc-PH (P < 0.001). In cohort B, the inverse relationship of pulmonary vascular compliance and resistance, as well as that of RC time and PWP, in Cpc-PH was similar to that in PAH and distinct from that in Ipc-PH. Our findings demonstrate that patients with Cpc-PH have pulmonary vascular physiology that resembles that of patients with PAH more than that of Ipc-PH patients. Further study is warranted to identify determinants of vascular remodeling and assess therapeutic response in this subset of PH.
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Affiliation(s)
- Tufik R. Assad
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Evan L. Brittain
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Quinn S. Wells
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Eric H. Farber-Eger
- Center for Human Genetics Research, Vanderbilt University, Nashville, Tennessee, USA
| | - Stephen J. Halliday
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Laura N. Doss
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Meng Xu
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, USA
| | - Li Wang
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, USA
| | - Frank E. Harrell
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, USA
| | - Chang Yu
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, USA
| | - Ivan M. Robbins
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - John H. Newman
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Anna R. Hemnes
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Guseh JS. The Evolving Landscape of Exercise-Induced Pulmonary Hypertension. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2016; 18:41. [PMID: 27174296 DOI: 10.1007/s11936-016-0459-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OPINION STATEMENT Normal pulmonary artery pressures at rest, with an exaggerated rise during exercise, characterize exercise-induced pulmonary hypertension. Exercise itself as it relates to this condition is not deleterious, nor does it cause or induce disease. However much like any classical stress test, it is a physiologic probe that aids in disease unmasking. Although more work is required to establish criteria for defining this clinical entity, the phenomenon is real. It remains unknown whether it represents a nascent form of cardiopulmonary disease and whether its genesis predicts fulminant cardiopulmonary disease. Incremental cardiopulmonary exercise testing and the construction of pressure-flow plots to describe the pulmonary vascular response to exercise will be essential in defining this disease. The critical first step remains a consensus definition that will allow for further prospective study focused by a common language.
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Affiliation(s)
- J Sawalla Guseh
- Department of Medicine, Division of Cardiology, Yawkey Center for Outpatient Care, Massachusetts General Hospital, 5th Floor 32 Fruit Street, Boston, MA, 02114, USA.
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15
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Sodium Nitroprusside in Patients With Mixed Pulmonary Hypertension and Left Heart Disease: Hemodynamic Predictors of Response and Prognostic Implications. J Card Fail 2016; 22:117-24. [DOI: 10.1016/j.cardfail.2015.10.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 10/25/2015] [Accepted: 10/27/2015] [Indexed: 11/18/2022]
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16
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Mosier JM, Joshi R, Hypes C, Pacheco G, Valenzuela T, Sakles JC. The Physiologically Difficult Airway. West J Emerg Med 2015; 16:1109-17. [PMID: 26759664 PMCID: PMC4703154 DOI: 10.5811/westjem.2015.8.27467] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 08/16/2015] [Accepted: 08/17/2015] [Indexed: 12/28/2022] Open
Abstract
Airway management in critically ill patients involves the identification and management of the potentially difficult airway in order to avoid untoward complications. This focus on difficult airway management has traditionally referred to identifying anatomic characteristics of the patient that make either visualizing the glottic opening or placement of the tracheal tube through the vocal cords difficult. This paper will describe the physiologically difficult airway, in which physiologic derangements of the patient increase the risk of cardiovascular collapse from airway management. The four physiologically difficult airways described include hypoxemia, hypotension, severe metabolic acidosis, and right ventricular failure. The emergency physician should account for these physiologic derangements with airway management in critically ill patients regardless of the predicted anatomic difficulty of the intubation.
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Affiliation(s)
- Jarrod M Mosier
- University of Arizona, Department of Emergency Medicine, Tucson, Arizona; University of Arizona, Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, Tucson, Arizona
| | - Raj Joshi
- University of Arizona, Department of Emergency Medicine, Tucson, Arizona; University of Arizona, Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, Tucson, Arizona
| | - Cameron Hypes
- University of Arizona, Department of Emergency Medicine, Tucson, Arizona; University of Arizona, Department of Medicine, Division of Pulmonary, Critical Care, Allergy and Sleep, Tucson, Arizona
| | - Garrett Pacheco
- University of Arizona, Department of Emergency Medicine, Tucson, Arizona
| | - Terence Valenzuela
- University of Arizona, Department of Emergency Medicine, Tucson, Arizona
| | - John C Sakles
- University of Arizona, Department of Emergency Medicine, Tucson, Arizona
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Zhou J, Esmaily-Moghadam M, Conover TA, Hsia TY, Marsden AL, Figliola RS. In Vitro Assessment of the Assisted Bidirectional Glenn Procedure for Stage One Single Ventricle Repair. Cardiovasc Eng Technol 2015; 6:256-67. [PMID: 26577359 DOI: 10.1007/s13239-015-0232-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 06/25/2015] [Indexed: 11/28/2022]
Abstract
This in vitro study compares the hemodynamic performance of the Norwood and the Glenn circulations to assess the performance of a novel assisted bidirectional Glenn (ABG) procedure for stage one single ventricle surgery. In the ABG, the flow in a bidirectional Glenn procedure is assisted by injection of a high-energy flow stream from the systemic circulation using an aorta-caval shunt with nozzle. The aim is to explore experimentally the potential of the ABG as a surgical alternative to current surgical practice. The experiments are directly compared against previously published numerical simulations. A multiscale mock circulatory system was used to measure the hemodynamic performance of the three circulations. For each circulation, the system was tested using both low and high values of pulmonary vascular resistance. Resulting parameters measured were: pressure and flow rate at left/right pulmonary artery and superior vena cava (SVC). Systemic oxygen delivery (OD) was calculated. A parametric study of the ratio of ABG nozzle to shunt diameter was done. We report time-based comparisons with numerical simulations for the three surgical variants tested. The ABG circulation demonstrated an increase of 30-38% in pulmonary flow with a 2-3.7 mmHg increase in SVC pressure compared to the Glenn and a 4-14% higher systemic OD than either the Norwood or the Glenn. The nozzle/shunt diameter ratio affected the local hemodynamics. These experimental results agreed with those of the numerical model: mean flow values were not significantly different (p > 0.05) while mean pressures were comparable within 1.2 mmHg. The results verify the approaches providing two tools to study this complicated circulation. Using a realistic experimental model we demonstrate the performance of a novel surgical procedure with potential to improve patient hemodynamics in early palliation of the univentricular circulation.
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Affiliation(s)
- Jian Zhou
- Department of Mechanical Engineering, Clemson University, 247 Fluor Daniel Building, Clemson, SC, 29634, USA
| | | | - Timothy A Conover
- Department of Mechanical Engineering, Clemson University, 247 Fluor Daniel Building, Clemson, SC, 29634, USA
| | | | - Alison L Marsden
- Mechanical and Aerospace Engineering Department, University of California, San Diego, La Jolla, CA, USA
| | - Richard S Figliola
- Department of Mechanical Engineering, Clemson University, 247 Fluor Daniel Building, Clemson, SC, 29634, USA.
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Chemla D, Humbert M, Sitbon O, Montani D, Hervé P. Systolic and Mean Pulmonary Artery Pressures. Chest 2015; 147:943-950. [DOI: 10.1378/chest.14-1755] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Newman JH, Brittain EL, Robbins IM, Hemnes AR. Effect of acute arteriolar vasodilation on capacitance and resistance in pulmonary arterial hypertension. Chest 2015; 147:1080-1085. [PMID: 25340330 PMCID: PMC4388116 DOI: 10.1378/chest.14-1461] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 09/29/2014] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND Pulmonary vascular capacitance (PVC) is reduced in pulmonary arterial hypertension (PAH). In normal lung, PVC is largely a function of vascular compliance. In PAH, increased pulmonary vascular resistance (PVR) arises from the arterioles. PVR and PVC share pressure and volume variables. The dependency between the two qualities of the vascular bed is unclear in a state of intense vasoconstriction. METHODS We compared PVC and PVR before and during nitric oxide (NO) inhalation during right-sided heart catheterization in eight NO-responsive patients with PAH. NO only directly affects tone in parenchymal vessels. RESULTS During NO inhalation, pulmonary arterial systolic pressure decreased, 80 ± 20 SD to 48 ± 20 mm Hg, and stroke volume increased, 62 ± 19 mL to 86 ± 24 mL (P < .01). PVR dropped from 10 ± 4.4 Wood units to 4.7 ± 2.2 Wood units (P < .012), and PVC increased from 1.4 ± 1.1 mL/mm Hg to 3.2 ± 1.8 mL/mm Hg (P < .018). The magnitude of PVR drop was 57% ± 6% and the decrease in 1/PVC was 54% ± 14% (P = not significant). CONCLUSIONS In vasoresponsive PAH, PVC is a function of the pressure response of the vasoconstricted arterioles to stroke volume. Immediately upon vasodilation, the capacitance increases markedly. The compliance vessels are, thus, the same as the resistance vessels. The immediate reduction in pulmonary arterial pressure during NO inhalation suggests that large vessel remodeling is not a major contributor to systolic pressure in these patients.
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Affiliation(s)
- John H Newman
- Pulmonary Circulation Center, Divisions of Pulmonary and Critical Care Medicine and Cardiology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN.
| | - Evan L Brittain
- Pulmonary Circulation Center, Divisions of Pulmonary and Critical Care Medicine and Cardiology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN
| | - Ivan M Robbins
- Pulmonary Circulation Center, Divisions of Pulmonary and Critical Care Medicine and Cardiology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN
| | - Anna R Hemnes
- Pulmonary Circulation Center, Divisions of Pulmonary and Critical Care Medicine and Cardiology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN
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20
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Berger D, Bloechlinger S, Takala J, Sinderby C, Brander L. Heart-lung interactions during neurally adjusted ventilatory assist. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2014; 18:499. [PMID: 25212533 PMCID: PMC4189198 DOI: 10.1186/s13054-014-0499-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 08/19/2014] [Indexed: 12/27/2022]
Abstract
Introduction Assist in unison to the patient’s inspiratory neural effort and feedback-controlled limitation of lung distension with neurally adjusted ventilatory assist (NAVA) may reduce the negative effects of mechanical ventilation on right ventricular function. Methods Heart–lung interaction was evaluated in 10 intubated patients with impaired cardiac function using esophageal balloons, pulmonary artery catheters and echocardiography. Adequate NAVA level identified by a titration procedure to breathing pattern (NAVAal), 50% NAVAal, and 200% NAVAal and adequate pressure support (PSVal, defined clinically), 50% PSVal, and 150% PSVal were implemented at constant positive end-expiratory pressure for 20 minutes each. Results NAVAal was 3.1 ± 1.1cmH2O/μV and PSVal was 17 ± 2 cmH20. For all NAVA levels negative esophageal pressure deflections were observed during inspiration whereas this pattern was reversed during PSVal and PSVhigh. As compared to expiration, inspiratory right ventricular outflow tract velocity time integral (surrogating stroke volume) was 103 ± 4%, 109 ± 5%, and 100 ± 4% for NAVAlow, NAVAal, and NAVAhigh and 101 ± 3%, 89 ± 6%, and 83 ± 9% for PSVlow, PSVal, and PSVhigh, respectively (p < 0.001 level-mode interaction, ANOVA). Right ventricular systolic isovolumetric pressure increased from 11.0 ± 4.6 mmHg at PSVlow to 14.0 ± 4.6 mmHg at PSVhigh but remained unchanged (11.5 ± 4.7 mmHg (NAVAlow) and 10.8 ± 4.2 mmHg (NAVAhigh), level-mode interaction p = 0.005). Both indicate progressive right ventricular outflow impedance with increasing pressure support ventilation (PSV), but no change with increasing NAVA level. Conclusions Right ventricular performance is less impaired during NAVA compared to PSV as used in this study. Proposed mechanisms are preservation of cyclic intrathoracic pressure changes characteristic of spontaneous breathing and limitation of right-ventricular outflow impedance during inspiration, regardless of the NAVA level. Trial registration Clinicaltrials.gov Identifier: NCT00647361, registered 19 March 2008 Electronic supplementary material The online version of this article (doi:10.1186/s13054-014-0499-8) contains supplementary material, which is available to authorized users.
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21
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Abstract
Acute respiratory distress syndrome (ARDS) is characterised by diffuse alveolar damage and is frequently complicated by pulmonary hypertension (PH). Multiple factors may contribute to the development of PH in this setting. In this review, we report the results of a systematic search of the available peer-reviewed literature for papers that measured indices of pulmonary haemodynamics in patients with ARDS and reported on mortality in the period 1977 to 2010. There were marked differences between studies, with some reporting strong associations between elevated pulmonary arterial pressure or elevated pulmonary vascular resistance and mortality, whereas others found no such association. In order to discuss the potential reasons for these discrepancies, we review the physiological concepts underlying the measurement of pulmonary haemodynamics and highlight key differences between the concepts of resistance in the pulmonary and systemic circulations. We consider the factors that influence pulmonary arterial pressure, both in normal lungs and in the presence of ARDS, including the important effects of mechanical ventilation. Pulmonary arterial pressure, pulmonary vascular resistance and transpulmonary gradient (TPG) depend not alone on the intrinsic properties of the pulmonary vascular bed but are also strongly influenced by cardiac output, airway pressures and lung volumes. The great variability in management strategies within and between studies means that no unified analysis of these papers was possible. Uniquely, Bull et al. (Am J Respir Crit Care Med 182:1123-1128, 2010) have recently reported that elevated pulmonary vascular resistance (PVR) and TPG were independently associated with increased mortality in ARDS, in a large trial with protocol-defined management strategies and using lung-protective ventilation. We then considered the existing literature to determine whether the relationship between PVR/TPG and outcome might be causal. Although we could identify potential mechanisms for such a link, the existing evidence does not allow firm conclusions to be drawn. Nonetheless, abnormally elevated PVR/TPG may provide a useful index of disease severity and progression. Further studies are required to understand the role and importance of pulmonary vascular dysfunction in ARDS in the era of lung-protective ventilation.
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22
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Chemla D. Physiologie du couplage entre le ventricule droit et la circulation pulmonaire. MEDECINE INTENSIVE REANIMATION 2014. [DOI: 10.1007/s13546-014-0904-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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23
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Nichols MD, Choudhary R, Kodali S, Reichert WM. Coagulation-induced resistance to fluid flow in small-diameter vascular grafts and graft mimics measured by purging pressure. J Biomed Mater Res B Appl Biomater 2014; 101:1367-76. [PMID: 24591220 DOI: 10.1002/jbm.b.32954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 01/09/2013] [Accepted: 02/11/2013] [Indexed: 11/07/2022]
Abstract
In this study, the coagulation-induced resistance to flow in small-diameter nonpermeable Tygon tubes and permeable expanded polytetrafluoroethylene (ePTFE) vascular grafts was characterized by measuring the upstream pressure needed to purge the coagulum from the tube lumen. This purging pressure was monitored using a closed system that compressed the contents of the tubes at a constant rate. The pressure system was validated using a glycerin series with well-defined viscosities and precisely controlled reductions in cross-sectional area available for flow. This system was then used to systematically probe the upstream pressure buildup as fibrin glue, platelet-rich plasma (PRP) or whole blood coagulated in small-diameter Tygon tubing and or ePTFE grafts. The maximum purging pressures rose with increased clot maturity for fibrin glue, PRP, and whole blood in both Tygon and ePTFE tubes. Although the rapidly coagulating fibrin glue in nonpermeable Tygon tubing yielded highly consistent purging curves, the significantly longer and more variable clotting times of PRP and whole blood, and the porosity of ePTFE grafts, significantly diminished the consistency of the purging curves.
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Affiliation(s)
- Michael D Nichols
- Department of Biomedical Engineering, Center for Biomolecular and Tissue Engineering, Duke University, Durham, North Carolina, 27708
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24
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Bouwmeester JC, Belenkie I, Shrive NG, Tyberg JV. Partitioning pulmonary vascular resistance using the reservoir-wave model. J Appl Physiol (1985) 2013; 115:1838-45. [DOI: 10.1152/japplphysiol.00750.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The conventional determination of pulmonary vascular resistance does not indicate which vascular segments contribute to the total resistance of the pulmonary circulation. Using measurements of pressure and flow, the reservoir-wave model can be used to partition total pulmonary vascular resistance into arterial, microcirculation, and venous components. Changes to these resistance components are investigated during hypoxia and inhaled nitric oxide, volume loading, and positive end-expiratory pressure. The reservoir-wave model defines the pressure of a volume-related reservoir and the asymptotic pressure. The mean values of arterial and venous reservoir pressures and arterial and venous asymptotic pressures define a series of resistances between the main pulmonary artery and the pulmonary veins: the resistance of large and small arteries, the microcirculation, and veins. In 11 anaesthetized, open-chest dogs, pressure and flow were measured in the main pulmonary artery and a single pulmonary vein. Volume loading reduced each vascular resistance component, whereas positive end-expiratory pressure only increased microcirculation resistance. Hypoxia increased the resistance of small arteries and veins, whereas nitric oxide only decreased small-artery resistance significantly. The reservoir-wave model provides a novel method to deconstruct total pulmonary vascular resistance. The results are consistent with the expected physiological responses of the pulmonary circulation and provide additional information regarding which segments of the pulmonary circulation react to hypoxia and nitric oxide.
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Affiliation(s)
| | - Israel Belenkie
- Libin Cardiovascular Institute of Alberta and
- Departments of 2Cardiac Sciences,
- Medicine,
| | | | - John V. Tyberg
- Libin Cardiovascular Institute of Alberta and
- Departments of 2Cardiac Sciences,
- Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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Evaluation of a model-based hemodynamic monitoring method in a porcine study of septic shock. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2013; 2013:505417. [PMID: 23585774 PMCID: PMC3621159 DOI: 10.1155/2013/505417] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/22/2013] [Accepted: 02/06/2013] [Indexed: 01/20/2023]
Abstract
INTRODUCTION The accuracy and clinical applicability of an improved model-based system for tracking hemodynamic changes is assessed in an animal study on septic shock. METHODS This study used cardiovascular measurements recorded during a porcine trial studying the efficacy of large-pore hemofiltration for treating septic shock. Four Pietrain pigs were instrumented and induced with septic shock. A subset of the measured data, representing clinically available measurements, was used to identify subject-specific cardiovascular models. These models were then validated against the remaining measurements. RESULTS The system accurately matched independent measures of left and right ventricle end diastolic volumes and maximum left and right ventricular pressures to percentage errors less than 20% (except for the 95th percentile error in maximum right ventricular pressure) and all R(2) > 0.76. An average decrease of 42% in systemic resistance, a main cardiovascular consequence of septic shock, was observed 120 minutes after the infusion of the endotoxin, consistent with experimentally measured trends. Moreover, modelled temporal trends in right ventricular end systolic elastance and afterload tracked changes in corresponding experimentally derived metrics. CONCLUSIONS These results demonstrate that this model-based method can monitor disease-dependent changes in preload, afterload, and contractility in porcine study of septic shock.
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Tossavainen E, Soderberg S, Gronlund C, Gonzalez M, Henein MY, Lindqvist P. Pulmonary artery acceleration time in identifying pulmonary hypertension patients with raised pulmonary vascular resistance. Eur Heart J Cardiovasc Imaging 2013; 14:890-7. [DOI: 10.1093/ehjci/jes309] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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27
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Opotowsky AR, Ojeda J, Rogers F, Prasanna V, Clair M, Moko L, Vaidya A, Afilalo J, Forfia PR. A simple echocardiographic prediction rule for hemodynamics in pulmonary hypertension. Circ Cardiovasc Imaging 2012; 5:765-75. [PMID: 22914595 DOI: 10.1161/circimaging.112.976654] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pulmonary hypertension (PH) has diverse causes with heterogeneous physiology compelling distinct management. Differentiating patients with primarily elevated pulmonary vascular resistance (PVR) from those with PH predominantly because of elevated left-sided filling pressure is critical. METHODS AND RESULTS We reviewed hemodynamics, echocardiography, and clinical data for 108 patients seen at a referral PH clinic with transthoracic echocardiogram and right heart catheterization within 1 year. We derived a simple echocardiographic prediction rule to allow hemodynamic differentiation of PH attributed to pulmonary vascular disease (PH(PVD), defined as pulmonary artery wedge pressure [PAWP]≤15 mm Hg and PVR>3 WU). Age averaged 61.3±14.8 years, μPAWP and PVR were 16.4±7.1 mm Hg and 6.3±4.0 WU, respectively, and 52 (48.1%) patients fulfilled PH(PVD) hemodynamic criteria. The derived prediction rule ranged from -2 to +2 with higher scores suggesting higher probability of PH(PVD): +1 point for left atrial anterior-posterior dimension <3.2 cm; +1 for presence of a mid systolic notch or acceleration time <80 ms; -1 for lateral mitral E:e'>10; -1 for left atrial anterior-posterior dimension >4.2 cm. PVR increased stepwise with score (for -2, 0, and +2, μPVR were 2.5, 4.5, and 8.1 WU, respectively), whereas the inverse was true for pulmonary artery wedge pressure (corresponding μPAWP were 21.5, 16.5, and 10.4 mm Hg). Among subjects with complete data, the score had an area under the curve (AUC) of 0.921 for PH(PVD). A score ≥0 had 100% sensitivity and 69.3% positive predictive value for PH(PVD), with 62.3% specificity. No patients with a negative score had PH(PVD). Patients with a negative score and acceleration time >100 ms had normal PVR (μPVR=1.8 WU, range=0.7-3.2 WU). CONCLUSIONS We present a simple echocardiographic prediction rule that accurately defines PH hemodynamics, facilitates improved screening and focused clinical investigation for PH diagnosis and management.
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Affiliation(s)
- Alexander R Opotowsky
- Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA
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Abstract
The pulmonary circulation is a high-flow and low-pressure circuit, with an average resistance of 1 mmHg/min/L in young adults, increasing to 2.5 mmHg/min/L over four to six decades of life. Pulmonary vascular mechanics at exercise are best described by distensible models. Exercise does not appear to affect the time constant of the pulmonary circulation or the longitudinal distribution of resistances. Very high flows are associated with high capillary pressures, up to a 20 to 25 mmHg threshold associated with interstitial lung edema and altered ventilation/perfusion relationships. Pulmonary artery pressures of 40 to 50 mmHg, which can be achieved at maximal exercise, may correspond to the extreme of tolerable right ventricular afterload. Distension of capillaries that decrease resistance may be of adaptative value during exercise, but this is limited by hypoxemia from altered diffusion/perfusion relationships. Exercise in hypoxia is associated with higher pulmonary vascular pressures and lower maximal cardiac output, with increased likelihood of right ventricular function limitation and altered gas exchange by interstitial lung edema. Pharmacological interventions aimed at the reduction of pulmonary vascular tone have little effect on pulmonary vascular pressure-flow relationships in normoxia, but may decrease resistance in hypoxia, unloading the right ventricle and thereby improving exercise capacity. Exercise in patients with pulmonary hypertension is associated with sharp increases in pulmonary artery pressure and a right ventricular limitation of aerobic capacity. Exercise stress testing to determine multipoint pulmonary vascular pressures-flow relationships may uncover early stage pulmonary vascular disease.
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Affiliation(s)
- R NAEIJE
- Department of Physiology, Erasme Campus of the Free University of Brussels, CP 604, 808, Lennik road, B-1070 Brussels, BELGIUM, Tel +32 2 5553322, Fax +32 2 5554124
| | - N CHESLER
- University of Wisconsin at Madison, 2146 Engineering Centers Building, 1550 Engineering drive, Madison, Wisconsin 53706-1609, USA, Tel +1 608 265 8920, Fax +1 608 265 9239
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Revie JA, Stevenson DJ, Chase JG, Hann CE, Lambermont BC, Ghuysen A, Kolh P, Morimont P, Shaw GM, Desaive T. Clinical detection and monitoring of acute pulmonary embolism: proof of concept of a computer-based method. Ann Intensive Care 2011; 1:33. [PMID: 21906388 PMCID: PMC3224493 DOI: 10.1186/2110-5820-1-33] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 08/11/2011] [Indexed: 11/17/2022] Open
Abstract
Background The diagnostic ability of computer-based methods for cardiovascular system (CVS) monitoring offers significant clinical potential. This research tests the clinical applicability of a newly improved computer-based method for the proof of concept case of tracking changes in important hemodynamic indices due to the influence acute pulmonary embolism (APE). Methods Hemodynamic measurements from a porcine model of APE were used to validate the method. Of these measurements, only those that are clinically available or inferable were used in to identify pig-specific computer models of the CVS, including the aortic and pulmonary artery pressure, stroke volume, heart rate, global end diastolic volume, and mitral and tricuspid valve closure times. Changes in the computer-derived parameters were analyzed and compared with experimental metrics and clinical indices to assess the clinical applicability of the technique and its ability to track the disease state. Results The subject-specific computer models accurately captured the increase in pulmonary resistance (Rpul), the main cardiovascular consequence of APE, in all five pigs trials, which related well (R2 = 0.81) with the experimentally derived pulmonary vascular resistance. An increase in right ventricular contractility was identified, as expected, consistent with known reflex responses to APE. Furthermore, the modeled right ventricular expansion index (the ratio of right to left ventricular end diastolic volumes) closely followed the trends seen in the measured data (R2 = 0.92) used for validation, with sharp increases seen in the metric for the two pigs in a near-death state. These results show that the pig-specific models are capable of tracking disease-dependent changes in pulmonary resistance (afterload), right ventricular contractility (inotropy), and ventricular loading (preload) during induced APE. Continuous, accurate estimation of these fundamental metrics of cardiovascular status can help to assist clinicians with diagnosis, monitoring, and therapy-based decisions in an intensive care environment. Furthermore, because the method only uses measurements already available in the ICU, it can be implemented with no added risk to the patient and little extra cost. Conclusions This computer-based monitoring method shows potential for real-time, continuous diagnosis and monitoring of acute CVS dysfunction in critically ill patients.
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Affiliation(s)
- James A Revie
- Cardiovascular Research Center, University of Liege, Belgium.
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Schmitt B, Steendijk P, Ovroutski S, Lunze K, Rahmanzadeh P, Maarouf N, Ewert P, Berger F, Kuehne T. Pulmonary vascular resistance, collateral flow, and ventricular function in patients with a Fontan circulation at rest and during dobutamine stress. Circ Cardiovasc Imaging 2010; 3:623-31. [PMID: 20631032 DOI: 10.1161/circimaging.109.931592] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The role, interplay, and relative importance of the multifactorial hemodynamic and myocardial mechanisms causing dysfunction of the Fontan circulation remain incompletely understood. METHODS AND RESULTS Using an MRI catheterization technique, we performed a differential analysis of pulmonary vascular resistance and aortopulmonary collateral blood flow in conjunction with global ventricular pump function, myocontractility (end-systolic pressure-volume relation), and diastolic compliance (end-diastolic pressure-volume relation) in 10 patients with a Fontan circulation at rest and during dobutamine stress. Pulmonary and ventricular pressures were measured invasively and synchronized with velocity-encoded MRI-derived pulmonary and aortic blood flows and cine MRI-derived ventricular volumes. Pulmonary vascular resistance and end-systolic and end-diastolic pressure-volume relations were then determined. Aortopulmonary collateral flow was calculated as the difference between aortic and pulmonary flow. Compared to rest, dobutamine caused a small increase in mean pulmonary pressures (P<0.05). Collateral flow was significantly augmented (P<0.001) and contributed importantly to an increase in pulmonary flow (P<0.01). Pulmonary vascular resistance decreased significantly (P<0.01). Dobutamine did not increase stroke volumes significantly despite slightly enhanced contractility (end-systolic pressure-volume relation). Active early relaxation (τ) was inconspicuous, but the end-diastolic pressure-volume relation shifted upward, indicating reduced compliance. CONCLUSIONS In patients with a Fontan circulation, aortopulmonary collateral flow contributes substantially to enhanced pulmonary flow during stress. Our data indicate that pulmonary vascular response to augmented cardiac output was adequate, but decreased diastolic compliance was identified as an important component of ventricular dysfunction.
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Affiliation(s)
- Boris Schmitt
- Department of Congenital Heart Disease and Pediatric Cardiology, Deutsches Herzzentrum Berlin and The Charité, Medical University Berlin, Berlin, Germany
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Bohm SH, Thamm OC, von Sandersleben A, Bangert K, Langwieler TE, Tusman G, Strate TG, Standl TG. Alveolar recruitment strategy and high positive end-expiratory pressure levels do not affect hemodynamics in morbidly obese intravascular volume-loaded patients. Anesth Analg 2009; 109:160-3. [PMID: 19535706 DOI: 10.1213/ane.0b013e3181a801a3] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We evaluated the effect of the alveolar recruitment strategy and high positive end-expiratory pressure (PEEP) on hemodynamics in 20 morbidly obese (body mass index 50 +/- 9 kg/m2), intravascular volume-loaded patients undergoing laparoscopic surgery. The alveolar recruitment strategy was sequentially performed with and without capnoperitoneum and consisted of an upward PEEP trial, recruitment with 50-60 cm H2O of plateau pressure for 10 breaths, and a downward PEEP trial. Recruitment and high PEEP did not cause significant disturbances in any hemodynamic variable measured by systemic and pulmonary artery catheters. Transesophageal echocardiography revealed no differences in end-diastolic areas or evidence of segmental abnormalities in wall motion.
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Affiliation(s)
- Stephan H Bohm
- Clinic of Anesthesiology, University Hospital Hamburg-Eppendorf, Germany.
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Morimont P, Lambermont B, Ghuysen A, Gerard P, Kolh P, Lancellotti P, Tchana-Sato V, Desaive T, D'Orio V. Effective arterial elastance as an index of pulmonary vascular load. Am J Physiol Heart Circ Physiol 2008; 294:H2736-42. [DOI: 10.1152/ajpheart.00796.2007] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to test whether the simple ratio of right ventricular (RV) end-systolic pressure (Pes) to stroke volume (SV), known as the effective arterial elastance ( Ea), provides a valid assessment of pulmonary arterial load in case of pulmonary embolism- or endotoxin-induced pulmonary hypertension. Ventricular pressure-volume (PV) data (obtained with conductance catheters) and invasive pulmonary arterial pressure and flow waveforms were simultaneously recorded in two groups of six pure Pietran pigs, submitted either to pulmonary embolism ( group A) or endotoxic shock ( group B). Measurements were obtained at baseline and each 30 min after injection of autologous blood clots (0.3 g/kg) in the superior vena cava in group A and after endotoxin infusion in group B. Two methods of calculation of pulmonary arterial load were compared. On one hand, Ea provided by using three-element windkessel model (WK) of the pulmonary arterial system [ Ea(WK)] was referred to as standard computation. On the other hand, similar to the systemic circulation, Ea was assessed as the ratio of RV Pes to SV [ Ea(PV) = Pes/SV]. In both groups, although the correlation between Ea(PV) and Ea(WK) was excellent over a broad range of altered conditions, Ea(PV) systematically overestimated Ea(WK). This offset disappeared when left atrial pressure (Pla) was incorporated into Ea [ Ea * (PV) = (Pes − Pla)/SV]. Thus Ea * (PV), defined as the ratio of RV Pes minus Pla to SV, provides a convenient, useful, and simple method to assess the pulmonary arterial load and its impact on the RV function.
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Huez S, Naeije R. Exercise stress tests for detection and evaluation of pulmonary hypertension. Eur Heart J Suppl 2007. [DOI: 10.1093/eurheartj/sum024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Faoro V, Huez S, Giltaire S, Pavelescu A, van Osta A, Moraine JJ, Guenard H, Martinot JB, Naeije R. Effects of acetazolamide on aerobic exercise capacity and pulmonary hemodynamics at high altitudes. J Appl Physiol (1985) 2007; 103:1161-5. [PMID: 17615281 DOI: 10.1152/japplphysiol.00180.2007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aerobic exercise capacity is decreased at altitude because of combined decreases in arterial oxygenation and in cardiac output. Hypoxic pulmonary vasoconstriction could limit cardiac output in hypoxia. We tested the hypothesis that acetazolamide could improve exercise capacity at altitude by an increased arterial oxygenation and an inhibition of hypoxic pulmonary vasoconstriction. Resting and exercise pulmonary artery pressure (Ppa) and flow (Q) (Doppler echocardiography) and exercise capacity (cardiopulmonary exercise test) were determined at sea level, 10 days after arrival on the Bolivian altiplano, at Huayna Potosi (4,700 m), and again after the intake of 250 mg acetazolamide vs. a placebo three times a day for 24 h. Acetazolamide and placebo were administered double-blind and in a random sequence. Altitude shifted Ppa/Q plots to higher pressures and decreased maximum O2 consumption (V̇o2max). Acetazolamide had no effect on Ppa/Q plots but increased arterial O2 saturation at rest from 84 ± 5 to 90 ± 3% ( P < 0.05) and at exercise from 79 ± 6 to 83 ± 4% ( P < 0.05), and O2 consumption at the anaerobic threshold (V-slope method) from 21 ± 5 to 25 ± 5 ml·min−1·kg−1 ( P < 0.01). However, acetazolamide did not affect V̇o2max (from 31 ± 6 to 29 ± 7 ml·kg−1·min−1), and the maximum respiratory exchange ratio decreased from 1.2 ± 0.06 to 1.05 ± 0.03 ( P < 0.001). We conclude that acetazolamide does not affect maximum exercise capacity or pulmonary hemodynamics at high altitudes. Associated changes in the respiratory exchange ratio may be due to altered CO2 production kinetics.
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Affiliation(s)
- Vitalie Faoro
- Laboratory of Physiology, Faculty of Medicine, Free University of Brussels, Brussels, Belgium
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Rex S, Missant C, Segers P, Rossaint R, Wouters PF. Epoprostenol treatment of acute pulmonary hypertension is associated with a paradoxical decrease in right ventricular contractility. Intensive Care Med 2007; 34:179-89. [PMID: 17710383 DOI: 10.1007/s00134-007-0831-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 07/19/2007] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Prostacyclins have been suggested to exert positive inotropic effects which would render them particularly suitable for the treatment of right ventricular (RV) dysfunction due to acute pulmonary hypertension (PHT). Data on this subject are controversial, however, and vary with the experimental conditions. We studied the inotropic effects of epoprostenol at clinically recommended doses in an experimental model of acute PHT. DESIGN AND SETTING Prospective laboratory investigation in a university hospital laboratory. SUBJECTS Six pigs (36 +/- 7kg). INTERVENTIONS Pigs were instrumented with biventricular conductance catheters, a pulmonary artery (PA) flow probe, and a high-fidelity pulmonary pressure catheter. Incremental doses of epoprostenol (10, 15, 20, 30, 40ng kg(-1) min(-1)) were administered in undiseased animals and after induction of acute hypoxia-induced PHT. MEASUREMENTS AND RESULTS In acute PHT epoprostenol markedly reduced RV afterload (slopes of pressure-flow relationship in the PA from 7.0 +/- 0.6 to 4.2 +/- 0.7mmHg minl(-1)). This was associated with a paradoxical and dose-dependent decrease in RV contractility (slope of preload-recruitable stroke-work relationship from 3.0 +/- 0.4 to 1.6 +/- 0.2 mW s ml(-1); slope of endsystolic pressure-volume relationship from 1.5 +/- 0.3 to 0.7 +/- 0.3mmHg ml(-1)). Left ventricular contractility was reduced only at the highest dose. In undiseased animals epoprostenol did not affect vascular tone and produced a mild biventricular decrease in contractility. CONCLUSIONS Epoprostenol has no positive inotropic effects in vivo. In contrast, epoprostenol-induced pulmonary vasodilation in animals with acute PHT was associated with a paradoxical decrease in RV contractility. This effect is probably caused indirectly by the close coupling of RV contractility to RV afterload. However, data from normal animals suggest that mechanisms unrelated to vasodilation are also involved in the observed negative inotropic response to epoprostenol.
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Affiliation(s)
- Steffen Rex
- Section Centre for Experimental Anesthesiology, Emergency and Intensive Care Medicine, Department of Acute Medical Sciences, Katholieke Universiteit Leuven, Minderbroederstraat 19 - bus 7003, 3000 Leuven, Belgium
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Ikonomidis JS, Hilton EJ, Payne K, Harrell A, Finklea L, Clark L, Reeves S, Stroud RE, Leonardi A, Crawford FA, Spinale FG. Selective Endothelin-A Receptor Inhibition After Cardiac Surgery: A Safety and Feasibility Study. Ann Thorac Surg 2007; 83:2153-60; discussion 2161. [PMID: 17532415 DOI: 10.1016/j.athoracsur.2007.02.087] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 02/26/2007] [Accepted: 02/26/2007] [Indexed: 11/29/2022]
Abstract
BACKGROUND Increased synthesis and release of the bioactive peptide endothelin has been shown to change hemodynamics and postoperative recovery after cardiac surgery. However, the clinical effects of selective interruption of endothelin signaling have not been studied. Because the endothelin-A (ET-A) receptor subtype is the primary cardiovascular effector for endothelin, this study used the ET-A receptor antagonist sitaxsentan sodium (TBC11251Na) to evaluate: (1) dose-dependent changes in pulmonary artery pressure (PAP) and pulmonary (PVRI) and systemic (SVRI) vascular resistance index in patients undergoing on-pump coronary revascularization; and (2) whether ET-RA administration was associated with increased adverse events. METHODS Patients (n = 44, age, 62 +/- 1 years) were randomized to receive vehicle (n = 9) or different bolus infusions of ET-A receptor antagonist: 0.1 (n = 9), 0.5 (n = 9) 1.0 (n = 9), and 2.0 mg/kg (n = 8) at separation from cardiopulmonary bypass (CPB). Adverse events were tabulated until hospital discharge. Results were expressed as changes from a composite baseline value, or from time 0 due to a high degree of intrapatient measurement variability in the postoperative period. RESULTS PAP increased by 27% +/- 13% from baseline (19 +/- 1 mm Hg) in the vehicle group at 6 hours post-CPB (p < 0.05). PAP fell from this post-CPB vehicle value in a dose-dependent manner with the ET-A receptor antagonist; with a significant reduction observed at 2 mg/kg (7% +/- 8% increase from baseline, p < 0.05). PVRI was reduced by 28.6% +/- 16% from baseline (249 +/- 22 dyn x s x cm(-5) x m(-2)) in the 2 mg/kg ET-A receptor antagonist group at 30 minutes post-CPB and remained reduced up to 6 hours post-CPB (p < 0.05). SVRI was reduced from baseline (2770 +/- 106 dyn x s x cm(-5) x m(-2)) by 51% +/- 6% in the 2.0 mg/kg ET-A receptor antagonist group at 30 minutes post-CPB (p < 0.05) and remained reduced up to 6 hours post-CPB. A total of 203 adverse events were tabulated in the postoperative period and were equally distributed across the five treatment groups, with no direct attributions to ET-A receptor antagonist treatment. CONCLUSIONS This unique study demonstrates that heightened endothelin-A receptor activation contributes to hemodynamic changes in patients after CPB. Selective inhibition of the endothelin receptor system can be successfully and safely performed in patients undergoing cardiac surgery and thereby reveals a potential, and clinically relevant therapeutic target.
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Affiliation(s)
- John S Ikonomidis
- Division of Cardiothoracic Surgery, Cardiothoracic Surgical Laboratory, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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Missant C, Rex S, Segers P, Wouters PF. Levosimendan improves right ventriculovascular coupling in a porcine model of right ventricular dysfunction*. Crit Care Med 2007; 35:707-15. [PMID: 17255859 DOI: 10.1097/01.ccm.0000257326.96342.57] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Experimental data suggest that levosimendan has pulmonary vasodilatory properties which, in combination with its positive inotropic effects, would render it particularly attractive for the treatment of right ventricular dysfunction. To test this hypothesis, we developed an experimental model of right ventricular failure and analyzed the effects of levosimendan on ventriculovascular coupling between the right ventricle and pulmonary artery (PA). DESIGN Prospective, randomized, placebo-controlled animal study. SETTING University hospital laboratory. SUBJECTS Fourteen pigs (mean weight 36 +/- 1 kg). INTERVENTIONS Pigs were instrumented with biventricular conductance catheters, a PA and right coronary artery flow probe, and a high-fidelity pulmonary pressure catheter. Right ventricular dysfunction was induced by repetitive episodes of ischemia/reperfusion in the presence of temporary PA constriction. Pigs were randomly assigned to receive levosimendan (120 mg/kg/hr [corrected] for 10 mins followed by continuous infusion of 60 mg/kg/hr [corrected] for 45 mins) or the placebo (control). MEASUREMENTS AND MAIN RESULTS Induction of right ventricular dysfunction resulted in a 42% decrease in contractility (reduction in slope of preload recruitable stroke work [Mw] from 2.5 +/- 0.4 to 1.8 +/- 0.5 mW x sec x mL(-1); p = .02) and a 60% increase in right ventricular afterload (effective pulmonary arterial elastance [PA-Ea] from 0.6 +/- 0.1 to 1.0 +/- 0.3 mm Hg x mL(-1); p < .01). Right ventriculovascular coupling, as assessed by the quotient of right ventricular end-systolic elastance (E(max)) over PA-Ea, decreased from 1.23 +/- 0.38 to 0.64 +/- 0.21 (p = .03). Treatment with levosimendan improved right ventricular contractility (Mw from 1.9 +/- 0.4 to 2.9 +/- 0.5 mW x sec x mL(-1); p < .01), lowered right ventricular afterload (PA-Ea from 1.1 +/- 0.3 to 0.8 +/- 0.3 mm Hg x mL(-1); p = .02), and restored right ventriculovascular coupling to normal values (E(max)/PA-Ea = 1.54 +/- 0.51). Levosimendan also significantly increased coronary blood flow and left ventricular contractility (Mw from 7.2 +/- 3.3 to 9.5 +/- 2.9 mW x sec x mL(-1); p = .01) but did not affect biventricular diastolic function. CONCLUSIONS In an experimental model of acute right ventricular dysfunction, levosimendan improved global hemodynamics and optimized right ventriculovascular coupling via a moderate increase in right ventricular contractility and a mild reduction of right ventricular afterload.
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Affiliation(s)
- Carlo Missant
- Center for Experimental Anesthesiology, Emergency and Intensive Care Medicine, Department of Acute Medical Sciences, Katholieke Universiteit Leuven, Belgium
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Rex S, Missant C, Segers P, Wouters PF. Thoracic epidural anesthesia impairs the hemodynamic response to acute pulmonary hypertension by deteriorating right ventricular-pulmonary arterial coupling. Crit Care Med 2007; 35:222-9. [PMID: 17095942 DOI: 10.1097/01.ccm.0000250357.35250.a2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Thoracic epidural anesthesia is increasingly used in critically ill patients. This analgesic technique was shown to decrease left ventricular contractility, but effects on right ventricular function have not been reported. A deterioration of right ventricular performance may be clinically relevant for patients with acute pulmonary hypertension, in which right ventricular function is an important determinant of outcome. In the present study, we tested the hypothesis that thoracic epidural anesthesia decreases right ventricular contractility and limits its capacity to tolerate pulmonary hypertension. DESIGN Prospective, placebo-controlled study using an established model of acute pulmonary hypertension. SETTING University hospital laboratory. SUBJECTS A total of 14 pigs (mean weight, 35 +/- 2 kg). INTERVENTIONS After instrumentation with an epidural catheter, biventricular conductance catheters, a pulmonary flow probe, and a high-fidelity pulmonary pressure catheter, seven pigs received thoracic epidural anesthesia and seven pigs served as control. Hemodynamic measurements were performed in baseline conditions and after induction of pulmonary hypertension via hypoxic pulmonary vasoconstriction (Fio2 of 0.15). MEASUREMENTS AND MAIN RESULTS Ventricular contractility was assessed using load- and heart rate-independent variables. Right ventricular afterload was characterized with instantaneous pressure-flow measurements. In baseline conditions, thoracic epidural anesthesia decreased left but not right ventricular contractility. In untreated animals, pulmonary hypertension was associated with an increase in right ventricular contractility and cardiac output. Pretreatment with thoracic epidural anesthesia completely abolished the positive inotropic response to acute pulmonary hypertension. As a result, ventriculo-vascular coupling between the right ventricle and pulmonary-arterial system deteriorated, and cardiac output was significantly lower in animals with thoracic epidural anesthesia than in untreated controls during hypoxia-induced pulmonary hypertension. CONCLUSIONS Thoracic epidural anesthesia inhibits the native positive inotropic response of the right ventricle to increased afterload and deteriorates the hemodynamic effects of acute pulmonary hypertension.
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Affiliation(s)
- Steffen Rex
- Laboratory for Experimental Anesthesiology, Department of Acute Medical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
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Lambermont B, D'Orio V. The role of right ventricular-pulmonary arterial coupling to differentiate between effects of inotropic agents in experimental right heart failure*. Crit Care Med 2006; 34:2864-5. [PMID: 17053580 DOI: 10.1097/01.ccm.0000242921.34042.0a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Miranda DR, Klompe L, Cademartiri F, Haitsma JJ, Palumbo A, Takkenberg JJM, Lachmann B, Bogers AJJC, Gommers D. The effect of open lung ventilation on right ventricular and left ventricular function in lung-lavaged pigs. Crit Care 2006; 10:R86. [PMID: 16764730 PMCID: PMC1550948 DOI: 10.1186/cc4944] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2006] [Revised: 04/18/2006] [Accepted: 05/11/2006] [Indexed: 12/02/2022] Open
Abstract
INTRODUCTION Ventilation according to the open lung concept (OLC) consists of recruitment maneuvers, followed by low tidal volume and high positive end-expiratory pressure, aiming at minimizing atelectasis. The minimization of atelectasis reduces the right ventricular (RV) afterload, but the increased intrathoracic pressures used by OLC ventilation could increase the RV afterload. We hypothesize that when atelectasis is minimized by OLC ventilation, cardiac function is not affected despite the higher mean airway pressure. METHODS After repeated lung lavage, each pig (n = 10) was conventionally ventilated and was ventilated according to OLC in a randomized cross-over setting. Conventional mechanical ventilation (CMV) consisted of volume-controlled ventilation with 5 cmH2O positive end-expiratory pressure and a tidal volume of 8-10 ml/kg. No recruitment maneuvers were performed. During OLC ventilation, recruitment maneuvers were applied until PaO2/FiO2 > 60 kPa. The peak inspiratory pressure was set to obtain a tidal volume of 6-8 ml/kg. The cardiac output (CO), the RV preload, the contractility and the afterload were measured with a volumetric pulmonary artery catheter. A high-resolution computed tomography scan measured the whole lung density and left ventricular (LV) volumes. RESULTS The RV end-systolic pressure-volume relationship, representing RV afterload, during steady-state OLC ventilation (2.7 +/- 1.2 mmHg/ml) was not significantly different compared with CMV (3.6 +/- 2.5 mmHg/ml). Pulmonary vascular resistance (OLC, 137 +/- 49 dynes/s/cm5 versus CMV, 130 +/- 34 dynes/s/cm5) was comparable between groups. OLC led to a significantly lower amount of atelectasis (13 +/- 2% of the lung area) compared with CMV (52 +/- 3% of the lung area). Atelectasis was not correlated with pulmonary vascular resistance or end-systolic pressure-volume relationship. The LV contractility and afterload during OLC was not significantly different compared with CMV. Compared with baseline, the LV end-diastolic volume (66 +/- 4 ml) decreased significantly during OLC (56 +/- 5 ml) ventilation and not during CMV (61 +/- 3 ml). Also, CO was significantly lower during OLC ventilation (OLC, 4.1 +/- 0.3 l/minute versus CMV, 4.9 +/- 0.3 l/minute). CONCLUSION In this experimental study, OLC resulted in significantly improved lung aeration. Despite the use of elevated airway pressures, no evidence was found for a negative effect of OLC on RV afterload or LV afterload, which might be associated with a loss of hypoxic pulmonary vasoconstriction due to alveolar recruitment. The reductions in the CO and in the mean pulmonary artery pressure were consequences of a reduced preload.
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Affiliation(s)
| | - Lennart Klompe
- Department of Cardio-Thoracic Surgery, Erasmus MC, Rotterdam, The Netherlands
| | | | - Jack J Haitsma
- Department of Anesthesiology, Erasmus MC, Rotterdam, The Netherlands
| | | | | | - Burkhard Lachmann
- Department of Anesthesiology, Erasmus MC, Rotterdam, The Netherlands
| | - Ad JJC Bogers
- Department of Cardio-Thoracic Surgery, Erasmus MC, Rotterdam, The Netherlands
| | - Diederik Gommers
- Department of Anesthesiology, Erasmus MC, Rotterdam, The Netherlands
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Tuchscherer HA, Webster EB, Chesler NC. Pulmonary Vascular Resistance and Impedance in Isolated Mouse Lungs: Effects of Pulmonary Emboli. Ann Biomed Eng 2006; 34:660-8. [PMID: 16568350 DOI: 10.1007/s10439-005-9050-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Accepted: 10/24/2005] [Indexed: 11/28/2022]
Abstract
To study pulsatile pressure-flow rate relationships in the intact pulmonary vascular network of mice, we developed a protocol for measuring pulmonary vascular resistance and impedance in isolated, ventilated, and perfused mouse lungs. We used pulmonary emboli to validate the effect of vascular obstruction on resistance and impedance. Main pulmonary artery and left atrial pressures and pulmonary vascular flow rate were measured under steady and pulsatile conditions in the lungs of C57BL/6J mice (n = 6) before and after two infusions with 25 microm-diameter microspheres (one million per infusion). After the first and second embolizations, pulmonary artery pressures increased approximately two-fold and three and a half-fold, respectively, compared to baseline, at a steady flow rate of 1 ml/min (P < 0.05). Pulmonary vascular resistance and 0 Hz impedance also increased after the first and second embolizations for all flow rates tested (P < 0.05). Frequency-dependent features of the pulmonary vascular impedance spectrum were suggestive of shifts in the major pulmonary vascular reflection sites with embolization. Our results demonstrate that pulmonary artery pressure, resistance, and impedance magnitude measured in this isolated lung setup changed in ways consistent with in vivo studies in larger animals and humans and demonstrate the usefulness of the isolated, ventilated, and perfused mouse lung for investigating steady and pulsatile pressure-flow rate relationships.
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Affiliation(s)
- Holly A Tuchscherer
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI 53706-1609, USA
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Nakhoul F, Yigla M, Gilman R, Reisner SA, Abassi Z. The pathogenesis of pulmonary hypertension in haemodialysis patients via arterio-venous access. Nephrol Dial Transplant 2005; 20:1686-92. [PMID: 15840664 DOI: 10.1093/ndt/gfh840] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND We recently have shown a high incidence of unexplained pulmonary hypertension (PHT) in end-stage renal disease (ESRD) patients on chronic haemodialysis (HD) therapy via arterio-venous (A-V) access. This study evaluated the possibility that PHT in these patients is triggered or aggravated by chronic HD via surgical A-V access, and the role of endothelin-1 (ET-1) and nitric oxide (NO) in this syndrome. METHODS Forty-two HD patients underwent clinical evaluation. Pulmonary artery pressure (PAP) was evaluated using Doppler echocardiography. Levels of ET-1 and NO metabolites in plasma were determined before and after the HD procedure and were compared between subgroups of patients with and without PHT. RESULTS Out of 42 HD patients studied, 20 patients (48%) had PHT (PAP = 46+/-2; range 36-82 mmHg) while the rest had a normal PAP (29+/-1 mmHg) (P<0.0001). HD patients with PHT had higher cardiac output compared with those with normal PAP (6.0+/-1.2 vs 5.2+/-0.9 l/min, P<0.034). HD patients, with or without PHT, had elevated plasma ET-1 levels compared with controls (1.6+/-0.7 and 2.4+/-0.8 fmol/ml vs 1.0+/-0.2, P<0.05) that remained unchanged after the HD procedure. HD patients without PHT and control subjects showed similar basal plasma levels of NO2 + NO3 (24.2+/-5.2 vs 19.7+/-3.1 microM, P>0.05) that was significantly higher compared with HD patients with PHT (14.3+/-2.3 microM, P<0.05). HD therapy caused a significant increase in plasma NO metabolites that was greater in patients without PHT (from 24.2+/-5.2 to 77.1+/-9.6 microM, P<0.0001, and from 14.3+/-2.3 to 39.9+/-11.4 microM, P<0.0074, respectively). Significant declines in PAP (from 49.8+/-2.8 to 38.6+/-2.2 mmHg, P<0.004) and cardiac output (CO) (from 7.6+/-0.6 to 6.1+/-0.3 l/min, P<0.03) were found in 11 HD patients with PHT that underwent successful transplantation. Similarly, temporary closure of the A-V access by a sphygmomanometer in eight patients with PHT resulted in a transient decrease in CO (from 6.4+/-0.6 to 5.3+/- 0.5 l/min, P = 0.18) and systolic PAP (from 47.2+/-3.8 to 34.6+/-2.8 mmHg, P<0.028). CONCLUSIONS This study demonstrates a high prevalence of PHT among patients with ESRD on chronic HD via a surgical A-V fistula. In view of the vasodilatory and antimitogenic properties of NO, it is possible that the attenuated basal and HD-induced NO production in patients with PHT contributes to the increased pulmonary vascular tone. Furthermore, the partial restoration of normal PAP and CO in HD patients that underwent either temporal A-V shunt closure or successful transplantation indicates that excessive pulmonary blood flow is involved in the pathogenesis of the disease.
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Affiliation(s)
- Farid Nakhoul
- Department of Nephrology, Rambam Medical Center, Haifa 31096, Israel.
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Reis Miranda D, Gommers D, Struijs A, Meeder H, Schepp R, Hop W, Bogers A, Klein J, Lachmann B. The open lung concept: effects on right ventricular afterload after cardiac surgery. Br J Anaesth 2004; 93:327-32. [PMID: 15247107 DOI: 10.1093/bja/aeh209] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The open lung concept (OLC) is a method of ventilation intended to maintain end-expiratory lung volume by increased airway pressure. Since this could increase right ventricular afterload, we studied the effect of this method on right ventricular afterload in patients after cardiac surgery. METHODS We studied 24 stable patients after coronary artery surgery and/or valve surgery with cardiopulmonary bypass. Patients were randomly assigned to OLC or conventional mechanical ventilation (CMV). In the OLC group, recruitment manoeuvres were applied until Pa(o(2))/FI(O(2)) was greater than 50 kPa (reflecting an open lung). This value was maintained by sufficient positive airway pressure. In the CMV group, volume-controlled ventilation was used with a PEEP of 5 cm H(2)O. Cardiac index, right ventricular preload, contractility and afterload were measured with a pulmonary artery thermodilution catheter during the 3-h observation period. Blood gases were monitored continuously. RESULTS To achieve Pa(O(2))/Fl(O(2)) > 50 kPa, 5.3 (3) (mean, SD) recruitment attempts were performed with a peak pressure of 45.5 (2) cm H(2)O. To keep the lung open, PEEP of 17.0 (3) cm H(2)O was required. Compared with baseline, pulmonary vascular resistance and right ventricular ejection fraction did not change significantly during the observation period in either group. CONCLUSION No evidence was found that ventilation according to the OLC affects right ventricular afterload.
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Affiliation(s)
- D Reis Miranda
- Department of Anesthesiology, Erasmus Medical Centre, Rotterdam, The Netherlands
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