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Karlsson LL, Van Muylem A, Linnarsson D. Lung diffusing capacity for nitric oxide in space: microgravity gas density interactions. Front Physiol 2023; 14:1161062. [PMID: 37228824 PMCID: PMC10203558 DOI: 10.3389/fphys.2023.1161062] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 04/19/2023] [Indexed: 05/27/2023] Open
Abstract
Introduction: During manned space exploration lung health is threatened by toxic planetary dust and radiation. Thus, tests such as lung diffusing capacity (DL) are likely be used in planetary habitats to monitor lung health. During a DL maneuver the rate of uptake of an inspired blood-soluble gas such as nitric oxide (NO) is determined (DLNO). The aim of this study was to investigate the influence of altered gravity and reduced atmospheric pressure on the test results, since the atmospheric pressure in a habitat on the moon or on Mars is planned to be lower than on Earth. Changes of gravity are known to alter the blood filling of the lungs which in turn may modify the rate of gas uptake into the blood, and changes of atmospheric pressure may alter the speed of gas transport in the gas phase. Methods: DLNO was determined in 11 subjects on the ground and in microgravity on the International Space Station. Experiments were performed at both normal (1.0 atm absolute, ata) and reduced (0.7 ata) atmospheric pressures. Results: On the ground, DLNO did not differ between pressures, but in microgravity DLNO was increased by 9.8% (9.5) (mean [SD]) and 18.3% (15.8) at 1.0 and 0.7 ata respectively, compared to normal gravity, 1.0 ata. There was a significant interaction between pressure and gravity (p = 0.0135). Discussion: Estimates of the membrane (DmNO) and gas phase (DgNO) components of DLNO suggested that at normal gravity a reduced pressure led to opposing effects in convective and diffusive transport in the gas phase, with no net effect of pressure. In contrast, a DLNO increase with reduced pressure at microgravity is compatible with a substantial increase of DmNO partially offset by reduced DgNO, the latter being compatible with interstitial edema. In microgravity therefore, DmNO would be proportionally underestimated from DLNO. We also conclude that normal values for DL in anticipation of planetary exploration should be determined not only on the ground but also at the gravity and pressure conditions of a future planetary habitat.
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Affiliation(s)
- Lars L. Karlsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | | | - Dag Linnarsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Zhang J, Liu W, Bi M, Xu J, Yang H, Zhang Y. Noble Gases Therapy in Cardiocerebrovascular Diseases: The Novel Stars? Front Cardiovasc Med 2022; 9:802783. [PMID: 35369316 PMCID: PMC8966230 DOI: 10.3389/fcvm.2022.802783] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 01/18/2022] [Indexed: 12/12/2022] Open
Abstract
Cardiocerebrovascular diseases (CCVDs) are the leading cause of death worldwide; therefore, to deeply explore the pathogenesis of CCVDs and to find the cheap and efficient strategies to prevent and treat CCVDs, these are of great clinical and social significance. The discovery of nitric oxide (NO), as one of the endothelium-derived relaxing factors and its successful utilization in clinical practice for CCVDs, provides new ideas for us to develop drugs for CCVDs: “gas medicine” or “medical gases.” The endogenous gas molecules such as carbon monoxide (CO), hydrogen sulfide (H2S), sulfur dioxide (SO2), methane (CH4), and hydrogen (H2) have essential biological effects on modulating cardiocerebrovascular homeostasis and CCVDs. Moreover, it has been shown that noble gas atoms such as helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) display strong cytoprotective effects and therefore, act as the exogenous pharmacologic preventive and therapeutic agents for CCVDs. Mechanistically, besides the competitive inhibition of N-methyl-D-aspartate (NMDA) receptor in nervous system by xenon, the key and common mechanisms of noble gases are involved in modulation of cell death and inflammatory or immune signals. Moreover, gases interaction and reduction in oxidative stress are emerging as the novel biological mechanisms of noble gases. Therefore, to investigate the precise actions of noble gases on redox signals, gases interaction, different cell death forms, and the emerging field of gasoimmunology, which focus on the effects of gas atoms/molecules on innate immune signaling or immune cells under both the homeostatic and perturbed conditions, these will help us to uncover the mystery of noble gases in modulating CCVDs.
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Affiliation(s)
- Jiongshan Zhang
- Department of Traditional Chinese Medicine, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Institute of Integrated Traditional Chinese and Western Medicine, Sun Yat-sen University, Guangzhou, China
| | - Wei Liu
- Department of Physiology, School of Basic Medical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China
- Research Centre for Integrative Medicine (Key Laboratory of Chinese Medicine Pathogenesis and Therapy Research), Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Mingmin Bi
- Department of Otorhinolaryngology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Jinwen Xu
- Department of Physiology, School of Basic Medical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China
- Research Centre for Integrative Medicine (Key Laboratory of Chinese Medicine Pathogenesis and Therapy Research), Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hongzhi Yang
- Department of Traditional Chinese Medicine, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Institute of Integrated Traditional Chinese and Western Medicine, Sun Yat-sen University, Guangzhou, China
| | - Yaxing Zhang
- Department of Physiology, School of Basic Medical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, China
- Research Centre for Integrative Medicine (Key Laboratory of Chinese Medicine Pathogenesis and Therapy Research), Guangzhou University of Chinese Medicine, Guangzhou, China
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Yoshida T, Uejima T, Komeda S, Matsuura K, Uemura A, Hayama H, Yamashita T, Yilmaz Z, Tanaka R. Estimation of Pulmonary Arterial Wave Reflection by Echo-Doppler: A Preliminary Study in Dogs With Experimentally-Induced Acute Pulmonary Embolism. Front Physiol 2021; 12:752550. [PMID: 34955877 PMCID: PMC8692872 DOI: 10.3389/fphys.2021.752550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/15/2021] [Indexed: 11/21/2022] Open
Abstract
Background: Pulmonary arterial (PA) wave reflection provides additional information for assessing right ventricular afterload, but its applications is hampered by the need for invasive pressure and flow measurements. We tested the hypothesis that PA pressure and flow waveforms estimated by Doppler echocardiography could be used to quantify PA wave reflection. Methods: Doppler echocardiographic images of tricuspid regurgitation and right ventricular outflow tract flow used to estimate PA pressure and flow waveforms were acquired simultaneously with direct measurements with a dual sensor-tipped catheter under various hemodynamic conditions in a canine model of pulmonary hypertension (n = 8). Wave separation analysis was performed on echo-Doppler derived as well as catheter derived waveforms to separate PA pressure into forward (Pf) and backward (Pb) pressures and derive wave reflection coefficient (RC) defined as the ratio of peak Pb to peak Pf. Results: Wave reflection indices by echo-Doppler agreed well with corresponding indices by catheter (Pb: mean difference = 0.4 mmHg, 95% limits of agreement = −4.3 to 5.0 mmHg; RC: bias = 0.13, 95% limits of agreement = −0.25 to 0.26). RC correlated negatively with PA compliance. Conclusion: This echo-Doppler method yields reasonable measurement of reflected wave in the pulmonary circulation, paving the way to a more integrative assessment of pulmonary hemodynamics in the clinical setting.
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Affiliation(s)
- Tomohiko Yoshida
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | | | - Syunta Komeda
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Katsuhiro Matsuura
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Akiko Uemura
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Hiromasa Hayama
- Department of Cardiology, National Center for Global Health and Medicine, Tokyo, Japan
| | | | - Zeki Yilmaz
- Department of Veterinary Internal Medicine, Bursa Uludag University, Bursa, Turkey
| | - Ryou Tanaka
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Fuchu, Japan
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Changes in the Pulmonary Artery Wave Reflection in Dogs with Experimentally-Induced Acute Pulmonary Embolism and the Effect of Vasodilator. Animals (Basel) 2021; 11:ani11071977. [PMID: 34359104 PMCID: PMC8300366 DOI: 10.3390/ani11071977] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Pulmonary hypertension (PH) remains a fatal disease, despite the advances in disease-specific therapies. This may be because the assessment of pulmonary hemodynamics in PH has not been established. Recently, several studies have reported that the pulmonary arterial wave reflection (PAWR) might influence the right ventricular afterload and could provide additional information regarding the severity and progression of PH. However, the pathophysiology of PAWR has some unclear points particularly in the case of acute pulmonary embolism (APE). The objective of this study was to investigate, for the first time, the characteristics of PAWR in a dog model of APE using dual-tipped sensor wire. From the result of the present study, after dogs developed PH by injections of dextran microsphere, PAWR was increased significantly along with the pulmonary vascular resistance (PVR) and reduced after vasodilator administration. In addition, PAWR was significantly correlated with PVR and right ventricular fractional area of change (FAC). These results indicating that PAWR may be useful as a new evaluation method in PH and may detect changes related to right ventricular afterload earlier than pulmonary artery pressure (PAP). Abstract Pulmonary hypertension (PH) is a complex syndrome that has been frequently diagnosed in dogs and humans and can be detected by Doppler echocardiography and invasive catheterization. Recently, PAWR attracts much attention as a noninvasive approach for the early detection of PH. The present study aims to investigate the PAWR changes in acute pulmonary embolism (APE) and highlight the response of PAWR variables to vasodilator therapy in dogs. For this purpose, anesthesia and catheterization were performed in 6 Beagle dogs. After that, APE was experimentally conducted by Dextran microsphere administration, followed by vasodilator (Nitroprusside; 1μg/kg/min/IV) administration. The hemodynamics, echocardiography, PVR and PAWR variables were evaluated at the baseline, after APE and after administration of nitroprusside. The result showed a significant increase in PVR, PAP, tricuspid regurgitation (TR) as well as PAWR variables following APE induction compared with the baseline (p < 0.05). Vasodilation caused by administration of nitroprusside reduced the mean atrial pressure, PVR and PAWR parameters. There were a significant correlation and linear regression between PAWR indices and PVR as well as right ventricular function parameters. In conclusion, PAWR is not only correlated with PVR but also the right ventricular function parameter, which indicates that PAWR may be useful as a new evaluation method in PH, considering that PAWR can assess both right ventricular afterload and right ventricular function.
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Schreier DA, Hacker TA, Tabima DM, Platt MO, Chesler NC. Effects of Red Blood Cell Sickling on Right Ventricular Afterload in vivo. EXPERIMENTAL MECHANICS 2021; 61:229-235. [PMID: 33776073 PMCID: PMC7992815 DOI: 10.1007/s11340-020-00669-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 09/28/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Hemolysis in sickle cell disease (SCD) releases cell free hemoglobin, which scavenges nitric oxide (NO), leading to pulmonary vascular vasoconstriction, increased pulmonary vascular resistance (PVR), and the development of PH. However, PVR is only one component of right ventricular (RV) afterload. Whether sickled red blood cells increase the total RV afterload, including compliance and wave reflections, is unclear. OBJECTIVE Patients with SCD and pulmonary hypertension (PH) have a significantly increased risk of sudden death compared to patients with SCD alone. Sickled red blood cells (RBCs) are fragile and lyse easily. Here, we sought to determine the acute effects of SCD RBCs and increased cell free hemoglobin on RV afterload. METHODS Main pulmonary artery pressures and flows were measured in C57BL6 mice before and after exchanges of whole blood (~200 uL, Hct=45%) with an equal volume of SCD RBCs in plasma (Hct=45%) or cell free hemoglobin (Hb+) in solution. After transfusions, animals were additionally stressed with acute hypoxia (AH; 10% O2). RESULTS SCD RBCs increased PVR only compared to control RBCs; cell free hemoglobin increased PVR and wave reflections. These increases in RV afterload increased further with AH. CONCLUSIONS The release of cell free hemoglobin from fragile SCD RBCs in vivo increases the total RV afterload and may impair RV function more than the SCD RBCs themselves.
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Affiliation(s)
- D A Schreier
- Department of Biomedical Engineering University of Wisconsin, 2146 ECB, 1550 Engineering Dr., Madison, WI 53706
| | - T A Hacker
- Department of Medicine 1685 Highland Avenue, 5158 Medical Foundation Centennial Building, Madison, WI 53705-2281
| | - D M Tabima
- Department of Biomedical Engineering University of Wisconsin, 2146 ECB, 1550 Engineering Dr., Madison, WI 53706
| | - M O Platt
- Department of Biomedical Engineering University of Georgia Tech, Engineered Biosystems Building, 950 Atlantic Drive, Suite 3015, Atlanta, GA 30332
| | - N C Chesler
- Department of Biomedical Engineering University of Wisconsin, 2146 ECB, 1550 Engineering Dr., Madison, WI 53706
- Department of Medicine 1685 Highland Avenue, 5158 Medical Foundation Centennial Building, Madison, WI 53705-2281
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Hertzog JH, Burr KL, Stump A, Brown JM, Penfil S, McMahon K. Impact of Helium-Oxygen Administered via High Velocity Nasal Insufflation on Delivery of Inhaled Nitric Oxide. J Pediatr Intensive Care 2020; 9:261-264. [PMID: 33133741 DOI: 10.1055/s-0040-1710057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 03/27/2020] [Indexed: 10/24/2022] Open
Abstract
Inhaled nitric oxide (iNO) may be continued during the transition from invasive to noninvasive respiratory support. Upper airway obstruction from laryngeal edema following extubation and lower airway obstruction from asthma and bronchiolitis may be managed with inhaled helium. The coadministration of helium with iNO and the impact on delivered amounts of iNO have not been extensively studied. A bench model simulating a spontaneously breathing infant received iNO at varying preset doses delivered with either helium-oxygen or nitrogen-oxygen via a Vapotherm unit. iNO levels were measured at the simulated trachea. Results from the two conditions were compared using t-tests. When nitrogen-oxygen was used, there was no difference between preset and measured iNO levels. A significant difference was present when helium-oxygen was used, with a 10-fold increase in measured iNO levels compared with preset values. The use of helium resulted in a significant increase in measured iNO at the level of the simulated trachea. Clinicians must be aware that iNO will not be delivered at prescribed doses when used with helium under the conditions used in this study.
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Affiliation(s)
- James H Hertzog
- Respiratory Care Services, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, United States.,Division of Critical Care Medicine, Department of Pediatrics, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, United States.,Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, United States
| | - Katlyn L Burr
- Respiratory Care Services, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, United States
| | - Angela Stump
- Respiratory Care Services, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, United States
| | - Joel M Brown
- Respiratory Care Services, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, United States
| | - Scott Penfil
- Department of Pediatrics, Samuelson Children's Hospital at Sinai, Baltimore, Maryland, United States
| | - Kimberly McMahon
- Division of Critical Care Medicine, Department of Pediatrics, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, United States.,Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, United States
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Wave Intensity Analysis of Right Ventricular Function during Pulsed Operation of Rotary Left Ventricular Assist Devices. ASAIO J 2018; 65:465-472. [PMID: 29863635 DOI: 10.1097/mat.0000000000000835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Changing the speed of left ventricular assist devices (LVADs) cyclically may be useful to restore aortic pulsatility; however, the effects of this pulsation on right ventricular (RV) function are unknown. This study investigates the effects of direct ventricular interaction by quantifying the amount of wave energy created by RV contraction when axial and centrifugal LVADs are used to assist the left ventricle. In 4 anesthetized pigs, pressure and flow were measured in the main pulmonary artery and wave intensity analysis was used to identify and quantify the energy of waves created by the RV. The axial pump depressed the intensity of waves created by RV contraction compared with the centrifugal pump. In both pump designs, there were only minor and variable differences between the continuous and pulsed operation on RV function. The axial pump causes the RV to contract with less energy compared with a centrifugal design. Diminishing the ability of the RV to produce less energy translates to less pressure and flow produced, which may lead to LVAD-induced RV failure. The effects of pulsed LVAD operation on the RV appear to be minimal during acute observation of healthy hearts. Further study is necessary to uncover the effects of other modes of speed modulation with healthy and unhealthy hearts to determine if pulsed operation will benefit patients by reducing LVAD complications.
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Su J, Logan CC, Hughes AD, Parker KH, Dhutia NM, Danielsen CC, Simonsen U. Impact of chronic hypoxia on proximal pulmonary artery wave propagation and mechanical properties in rats. Am J Physiol Heart Circ Physiol 2018; 314:H1264-H1278. [PMID: 29547024 PMCID: PMC6032080 DOI: 10.1152/ajpheart.00695.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 03/12/2018] [Accepted: 03/14/2018] [Indexed: 02/06/2023]
Abstract
Arterial stiffness and wave reflection are important components of the ventricular afterload. Therefore, we aimed to assess the arterial wave characteristics and mechanical properties of the proximal pulmonary arteries (PAs) in the hypoxic pulmonary hypertensive rat model. After 21 days in normoxic or hypoxic chambers (24 animals/group), animals underwent transthoracic echocardiography and PA catheterization with a dual-tipped pressure and Doppler flow sensor wire. Wave intensity analysis was performed. Artery rings obtained from the pulmonary trunk, right and left PAs, and aorta were subjected to a tensile test to rupture. Collagen and elastin content were determined. In hypoxic rats, proximal PA wall thickness, collagen content, tensile strength per unit collagen, maximal elastic modulus, and wall viscosity increased, whereas the elastin-to-collagen ratio and arterial distensibility decreased. Arterial pulse wave velocity was also increased, and the increase was more prominent in vivo than ex vivo. Wave intensity was similar in hypoxic and normoxic animals with negligible wave reflection. In contrast, the aortic maximal elastic modulus remained unchanged, whereas wall viscosity decreased. In conclusion, there was no evidence of altered arterial wave propagation in proximal PAs of hypoxic rats while the extracellular matrix protein composition was altered and collagen tensile strength increased. This was accompanied by altered mechanical properties in vivo and ex vivo. NEW & NOTEWORTHY In rats exposed to chronic hypoxia, we have shown that pulse wave velocity in the proximal pulmonary arteries increased and pressure dependence of the pulse wave velocity was steeper in vivo than ex vivo leading to a more prominent increase in vivo.
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Affiliation(s)
- Junjing Su
- Department of Biomedicine, Aarhus University , Aarhus , Denmark
| | | | - Alun D Hughes
- Institute of Cardiovascular Science, University College London , London , United Kingdom
| | - Kim H Parker
- Department of Bioengineering, Imperial College London , London , United Kingdom
| | - Niti M Dhutia
- Department of Bioengineering, Imperial College London , London , United Kingdom
| | | | - Ulf Simonsen
- Department of Biomedicine, Aarhus University , Aarhus , Denmark
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Carotid artery stiffness evaluated early by wave intensity in normal left ventricular function in post-radiotherapy patients with nasopharyngeal carcinoma. J Med Ultrason (2001) 2017; 45:301-306. [DOI: 10.1007/s10396-017-0817-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/27/2017] [Indexed: 10/18/2022]
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Su J, Hilberg O, Howard L, Simonsen U, Hughes AD. A review of wave mechanics in the pulmonary artery with an emphasis on wave intensity analysis. Acta Physiol (Oxf) 2016; 218:239-249. [PMID: 27636734 PMCID: PMC5120692 DOI: 10.1111/apha.12803] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/02/2016] [Accepted: 09/13/2016] [Indexed: 01/10/2023]
Abstract
Mean pulmonary arterial pressure and pulmonary vascular resistance (PVR) remain the most common haemodynamic measures to evaluate the severity and prognosis of pulmonary hypertension. However, PVR only captures the non-oscillatory component of the right ventricular hydraulic load and neglects the dynamic compliance of the pulmonary arteries and the contribution of wave transmission. Wave intensity analysis offers an alternative way to assess the pulmonary vasculature in health and disease. Wave speed is a measure of arterial stiffness, and the magnitude and timing of wave reflection provide information on the degree of impedance mismatch between the proximal and distal circulation. Studies in the pulmonary artery have demonstrated distinct differences in arterial wave propagation between individuals with and without pulmonary vascular disease. Notably, greater wave speed and greater wave reflection are observed in patients with pulmonary hypertension and in animal models exposed to hypoxia. Studying wave propagation makes a valuable contribution to the assessment of the arterial system in pulmonary hypertension, and here, we briefly review the current state of knowledge of the methods used to evaluate arterial waves in the pulmonary artery.
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Affiliation(s)
- Junjing Su
- Department of Biomedicine – Pharmacology, Aarhus University
- National Heart and Lung Institute, Imperial College London
| | - Ole Hilberg
- Department of Respiratory Medicine, Aarhus University Hospital
| | - Luke Howard
- National Heart and Lung Institute, Imperial College London
| | - Ulf Simonsen
- Department of Biomedicine – Pharmacology, Aarhus University
| | - Alun D Hughes
- National Heart and Lung Institute, Imperial College London
- Institute of Cardiovascular Science, University College London
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Bouwmeester JC, Belenkie I, Shrive NG, Tyberg JV. Wave reflections in the pulmonary arteries analysed with the reservoir-wave model. J Physiol 2014; 592:3053-62. [PMID: 24756638 DOI: 10.1113/jphysiol.2014.273094] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Conventional haemodynamic analysis of pressure and flow in the pulmonary circulation yields incident and reflected waves throughout the cardiac cycle, even during diastole. The reservoir-wave model provides an alternative haemodynamic analysis consistent with minimal wave activity during diastole. Pressure and flow in the main pulmonary artery were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading and positive end-expiratory pressure were observed. The reservoir-wave model was used to determine the reservoir contribution to pressure and flow and once subtracted, resulted in 'excess' quantities, which were treated as wave-related. Wave intensity analysis quantified the contributions of waves originating upstream (forward-going waves) and downstream (backward-going waves). In the pulmonary artery, negative reflections of incident waves created by the right ventricle were observed. Overall, the distance from the pulmonary artery valve to this reflection site was calculated to be 5.7 ± 0.2 cm. During 100% O2 ventilation, the strength of these reflections increased 10% with volume loading and decreased 4% with 10 cmH2O positive end-expiratory pressure. In the pulmonary arterial circulation, negative reflections arise from the junction of lobar arteries from the left and right pulmonary arteries. This mechanism serves to reduce peak systolic pressure, while increasing blood flow.
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Affiliation(s)
| | - Israel Belenkie
- Libin Cardiovascular Institute of Alberta Departments of Cardiac Sciences Medicine
| | | | - John V Tyberg
- Libin Cardiovascular Institute of Alberta Departments of Cardiac Sciences Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
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Berganza CJ, Zhang JH. The role of helium gas in medicine. Med Gas Res 2013; 3:18. [PMID: 23916029 PMCID: PMC3751721 DOI: 10.1186/2045-9912-3-18] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/25/2013] [Indexed: 01/04/2023] Open
Abstract
The noble gas helium has many applications owing to its distinct physical and chemical characteristics, namely: its low density, low solubility, and high thermal conductivity. Chiefly, the abundance of studies in medicine relating to helium are concentrated in its possibility of being used as an adjunct therapy in a number of respiratory ailments such as asthma exacerbation, COPD, ARDS, croup, and bronchiolitis. Helium gas, once believed to be biologically inert, has been recently shown to be beneficial in protecting the myocardium from ischemia by various mechanisms. Though neuroprotection of brain tissue has been documented, the mechanism by which it does so has yet to be made clear. Surgeons are exploring using helium instead of carbon dioxide to insufflate the abdomen of patients undergoing laparoscopic abdominal procedures due to its superiority in preventing respiratory acidosis in patients with comorbid conditions that cause carbon dioxide retention. Newly discovered applications in Pulmonary MRI radiology and imaging of organs in very fine detail using Helium Ion Microscopy has opened exciting new possibilities for the use of helium gas in technologically advanced fields of medicine.
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Affiliation(s)
- Carlos J Berganza
- Departments of Neurosurgery and Physiology, Loma Linda University, Loma Linda California, USA.
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Liu W, Khatibi N, Sridharan A, Zhang JH. Application of medical gases in the field of neurobiology. Med Gas Res 2011; 1:13. [PMID: 22146102 PMCID: PMC3231869 DOI: 10.1186/2045-9912-1-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 06/27/2011] [Indexed: 12/11/2022] Open
Abstract
Medical gases are pharmaceutical molecules which offer solutions to a wide array of medical needs. This can range from use in burn and stroke victims to hypoxia therapy in children. More specifically however, gases such as oxygen, helium, xenon, and hydrogen have recently come under increased exploration for their potential theraputic use with various brain disease states including hypoxia-ischemia, cerebral hemorrhages, and traumatic brain injuries. As a result, this article will review the various advances in medical gas research and discuss the potential therapeutic applications and mechanisms with regards to the field of neurobiology.
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Affiliation(s)
- Wenwu Liu
- Department of Anesthesiology, Loma Linda Medical Center, Loma Linda, California, USA.
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