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Jani VP, Jani VP, Munoz CJ, Govender K, Williams AT, Cabrales P. Application of negative tissue interstitial pressure improves functional capillary density after hemorrhagic shock in the absence of volume resuscitation. Physiol Rep 2021; 9:e14783. [PMID: 33661575 PMCID: PMC7931804 DOI: 10.14814/phy2.14783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 02/05/2021] [Indexed: 11/24/2022] Open
Abstract
Microvascular fluid exchange is primarily dependent on Starling forces and both the active and passive myogenic response of arterioles and post-capillary venules. Arterioles are classically considered resistance vessels, while venules are considered capacitance vessels with high distensibility and low tonic sympathetic stimulation at rest. However, few studies have investigated the effects of modulating interstitial hydrostatic pressure, particularly in the context of hemorrhagic shock. The objective of this study was to investigate the mechanics of arterioles and functional capillary density (FCD) during application of negative tissue interstitial pressure after 40% total blood volume hemorrhagic shock. In this study, we characterized systemic and microcirculatory hemodynamic parameters, including FCD, in hamsters instrumented with a dorsal window chamber and a custom-designed negative pressure application device via intravital microscopy. In large arterioles, application of negative pressure after hemorrhagic shock resulted in a 13 ± 11% decrease in flow compared with only a 7 ± 9% decrease in flow after hemorrhagic shock alone after 90 minutes. In post-capillary venules, however, application of negative pressure after hemorrhagic shock resulted in a 31 ± 4% decrease in flow compared with only an 8 ± 5% decrease in flow after hemorrhagic shock alone after 90 minutes. Normalized FCD was observed to significantly improve after application of negative pressure after hemorrhagic shock (0.66 ± 0.02) compared to hemorrhagic shock without application of negative pressure (0.50 ± 0.04). Our study demonstrates that application of negative pressure acutely improves FCD during hemorrhagic shock, though it does not normalize FCD. These results suggest that by increasing the hydrostatic pressure gradient between the microvasculature and interstitium, microvascular perfusion can be transiently restored in the absence of volume resuscitation. This study has significant clinical implications, particularly in negative pressure wound therapy, and offers an alternative mechanism to improve microvascular perfusion during hypovolemic shock.
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Affiliation(s)
- Vinay P. Jani
- Department of BioengineeringUniversity of CaliforniaSan DiegoLa JollaCAUSA
| | - Vivek P. Jani
- Division of CardiologyDepartment of MedicineThe Johns Hopkins UniversityThe Johns Hopkins School of Medicine BaltimoreMDUSA
| | - Carlos J. Munoz
- Department of BioengineeringUniversity of CaliforniaSan DiegoLa JollaCAUSA
| | - Krianthan Govender
- Department of BioengineeringUniversity of CaliforniaSan DiegoLa JollaCAUSA
| | | | - Pedro Cabrales
- Department of BioengineeringUniversity of CaliforniaSan DiegoLa JollaCAUSA
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Munoz C, Aletti F, Govender K, Cabrales P, Kistler EB. Resuscitation After Hemorrhagic Shock in the Microcirculation: Targeting Optimal Oxygen Delivery in the Design of Artificial Blood Substitutes. Front Med (Lausanne) 2020; 7:585638. [PMID: 33195342 PMCID: PMC7652927 DOI: 10.3389/fmed.2020.585638] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/18/2020] [Indexed: 11/25/2022] Open
Abstract
Microcirculatory preservation is essential for patient recovery from hemorrhagic shock. In hemorrhagic shock, microcirculatory flow and pressure are greatly reduced, creating an oxygen debt that may eventually become irreversible. During shock, tissues become hypoxic, cellular respiration turns to anaerobic metabolism, and the microcirculation rapidly begins to fail. This condition requires immediate fluid resuscitation to promote tissue reperfusion. The choice of fluid for resuscitation is whole blood; however, this may not be readily available and, on a larger scale, may be globally insufficient. Thus, extensive research on viable alternatives to blood has been undertaken in an effort to develop a clinically deployable blood substitute. This has not, as of yet, achieved fruition, in part due to an incomplete understanding of the complexities of the function of blood in the microcirculation. Hemodynamic resuscitation is acknowledged to be contingent on a number of factors other than volume expansion. The circulation of whole blood is carefully regulated to optimize oxygen delivery to the tissues via shear stress modulation through blood viscosity, inherent oxygen-carrying capacity, cell-free layer variation, and myogenic response, among other variables. Although plasma expanders can address a number of these issues, hemoglobin-based oxygen carriers (HBOCs) introduce a method of replenishing the intrinsic oxygen-carrying capacity of blood. There continue to be a number of issues related to HBOCs, but recent advances in the next-generation HBOCs show promise in the preservation of microcirculatory function and limiting toxicities. The development of HBOCs is now focused on viscosity and the degree of microvascular shear stress achieved in order to optimize vasoactive and oxygen delivery responses by leveraging the restoration and maintenance of physiological responses to blood flow in the microcirculation. Blood substitutes with higher viscous properties tend to improve oxygen delivery compared to those with lower viscosities. This review details current concepts in blood substitutes, particularly as they relate to trauma/hemorrhagic shock, with a specific focus on their complex interactions in the microcirculation.
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Affiliation(s)
- Carlos Munoz
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States
| | - Federico Aletti
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States
| | - Krianthan Govender
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States
| | - Pedro Cabrales
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States
| | - Erik B Kistler
- Department of Anesthesiology and Critical Care, University of California, San Diego, La Jolla, CA, United States.,Department of Anesthesiology and Critical Care, Veterans Affairs San Diego Healthcare System, San Diego, CA, United States
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Naumann DN, Hazeldine J, Bishop J, Midwinter MJ, Harrison P, Nash G, Hutchings SD. Impact of plasma viscosity on microcirculatory flow after traumatic haemorrhagic shock: A prospective observational study. Clin Hemorheol Microcirc 2019; 71:71-82. [PMID: 29843227 DOI: 10.3233/ch-180397] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Preclinical studies report that higher plasma viscosity improves microcirculatory flow after haemorrhagic shock and resuscitation, but no clinical study has tested this hypothesis. OBJECTIVE We investigated the relationship between plasma viscosity and sublingual microcirculatory flow in patients during resuscitation for traumatic haemorrhagic shock (THS). METHODS Sublingual video-microscopy was performed for 20 trauma patients with THS as soon as feasible in hospital, and then at 24 h and 48 h. Values were obtained for total vessel density, perfused vessel density, proportion of perfused vessels, microcirculatory flow index (MFI), microcirculatory heterogeneity index (MHI), and Point of Care Microcirculation (POEM) scores. Plasma viscosity was measured using a Wells-Brookfield cone and plate micro-viscometer. Logistic regression analyses examined relationships between microcirculatory parameters and plasma viscosity, adjusting for covariates (systolic blood pressure, heart rate, haematocrit, rate and volume of fluids, and rate of noradrenaline). RESULTS Higher plasma viscosity was not associated with improved microcirculatory parameters. Instead, there were weakly significant associations between higher plasma viscosity and lower (poorer) MFI (p = 0.040), higher (worse) MHI (p = 0.033), and lower (worse) POEM scores (p = 0.039). CONCLUSIONS The current study did not confirm the hypothesis that higher plasma viscosity improves microcirculatory flow dynamics in patients with THS. Further clinical investigations are warranted to determine whether viscosity is a physical parameter of importance during resuscitation of these patients.
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Affiliation(s)
- David N Naumann
- Academic Department of Military Surgery and Trauma, Royal Centre for Defence Medicine, Queen Elizabeth Hospital, Birmingham, UK.,Institute of Inflammation and Ageing, University of Birmingham Research Laboratories, Queen Elizabeth Hospital, Birmingham, UK.,National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, Birmingham, UK
| | - Jon Hazeldine
- Institute of Inflammation and Ageing, University of Birmingham Research Laboratories, Queen Elizabeth Hospital, Birmingham, UK.,National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, Birmingham, UK
| | - Jon Bishop
- National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital, Birmingham, UK
| | - Mark J Midwinter
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Paul Harrison
- Institute of Inflammation and Ageing, University of Birmingham Research Laboratories, Queen Elizabeth Hospital, Birmingham, UK
| | - Gerard Nash
- Institute of Cardiovascular Science, University of Birmingham, UK
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Abstract
The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.
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Affiliation(s)
- Ivo Torres Filho
- US Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas, USA
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Torres Filho IP, Torres LN, Salgado C, Dubick MA. Plasma syndecan-1 and heparan sulfate correlate with microvascular glycocalyx degradation in hemorrhaged rats after different resuscitation fluids. Am J Physiol Heart Circ Physiol 2016; 310:H1468-78. [DOI: 10.1152/ajpheart.00006.2016] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/31/2016] [Indexed: 01/24/2023]
Abstract
The endothelial glycocalyx plays an essential role in many physiological functions and is damaged after hemorrhage. Fluid resuscitation may further change the glycocalyx after an initial hemorrhage-induced degradation. Plasma levels of syndecan-1 and heparan sulfate have been used as indirect markers for glycocalyx degradation, but the extent to which these measures are representative of the events in the microcirculation is unknown. Using hemorrhage and a wide range of resuscitation fluids, we studied quantitatively the relationship between plasma biomarkers and changes in microvascular parameters, including glycocalyx thickness. Rats were bled 40% of total blood volume and resuscitated with seven different fluids (fresh whole blood, blood products, and crystalloids). Intravital microscopy was used to estimate glycocalyx thickness in >270 postcapillary venules from 58 cremaster preparations in 9 animal groups; other microvascular parameters were measured using noninvasive techniques. Systemic physiological parameters and blood chemistry were simultaneously collected. Changes in glycocalyx thickness were negatively correlated with changes in plasma levels of syndecan-1 ( r = −0.937) and heparan sulfate ( r = −0.864). Changes in microvascular permeability were positively correlated with changes in both plasma biomarkers ( r = 0.8, P < 0.05). Syndecan-1 and heparan sulfate were also positively correlated ( r = 0.7, P < 0.05). Except for diameter and permeability, changes in local microcirculatory parameters (red blood cell velocity, blood flow, and wall shear rate) did not correlate with plasma biomarkers or glycocalyx thickness changes. This work provides a quantitative framework supporting plasma syndecan-1 and heparan sulfate as valuable clinical biomarkers of glycocalyx shedding that may be useful in guiding resuscitation strategies following hemorrhage.
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Affiliation(s)
- Ivo P. Torres Filho
- Damage Control Resuscitation, US Army Institute of Surgical Research, Fort Sam Houston, Texas
| | - Luciana N. Torres
- Damage Control Resuscitation, US Army Institute of Surgical Research, Fort Sam Houston, Texas
| | - Christi Salgado
- Damage Control Resuscitation, US Army Institute of Surgical Research, Fort Sam Houston, Texas
| | - Michael A. Dubick
- Damage Control Resuscitation, US Army Institute of Surgical Research, Fort Sam Houston, Texas
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Ortiz D, Barros M, Yan S, Cabrales P. Resuscitation from hemorrhagic shock using polymerized hemoglobin compared to blood. Am J Emerg Med 2013; 32:248-55. [PMID: 24418449 DOI: 10.1016/j.ajem.2013.11.045] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 11/06/2013] [Accepted: 11/27/2013] [Indexed: 11/30/2022] Open
Abstract
The development of an alternative to blood transfusion to treat severe hemorrhage remains a challenge, especially in far forward scenarios when blood is not available. Hemoglobin level (Hb)-based oxygen (O2) carriers (HBOCs) were developed to address this need. Hemopure (HBOC-201, bovine Hb glutamer-250; OPK Biotech, Cambridge, MA), one such HBOC, has been approved for clinical use in South Africa and Russia. At the time of its approval, however, few studies aimed to understand Hemopure's function, administration, and adverse effects compared to blood. We used intravital microscopy to study the microcirculation hemodynamics (arteriolar and venular diameters and blood flow and functional capillary density [FCD]) and oxygenation implications of Hemopure administration at different Hb concentrations-4, 8, and 12 gHb/dL-compared to fresh blood transfusion during resuscitation from hemorrhagic shock. Experiments were performed in unanesthetized hamsters instrumented with a skinfold window chamber, subjected to hemorrhage (50% of the blood volume), followed by 1-hour hypovolemic shock and fluid resuscitation (50% of the shed volume). Our results show that fluid resuscitation with Hemopure or blood restored systemic and microvascular parameters. Microcirculation O2 delivery was directly correlated with Hemopure concentration, although increased vasoconstriction was as well. Functional capillary density reflected the balance between enhanced O2 transport and reduced blood flow: 12 gHb/dL of Hemopure and blood decreased FCD compared to the lower concentrations of Hemopure (P < .05). The balance between O2 transport and tissue perfusion can provide superior resuscitation from hemorrhagic shock compared to blood transfusion by using a low Hb concentration of HBOCs relative to blood.
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Affiliation(s)
- Daniel Ortiz
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA.
| | - Marcelo Barros
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA.
| | - Su Yan
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA.
| | - Pedro Cabrales
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA.
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Bonanno FG. Hemorrhagic shock: The "physiology approach". J Emerg Trauma Shock 2012; 5:285-95. [PMID: 23248495 PMCID: PMC3519039 DOI: 10.4103/0974-2700.102357] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 04/13/2011] [Indexed: 11/22/2022] Open
Abstract
A shift of approach from ‘clinics trying to fit physiology’ to the one of ‘physiology to clinics’, with interpretation of the clinical phenomena from their physiological bases to the tip of the clinical iceberg, and a management exclusively based on modulation of physiology, is finally surging as the safest and most efficacious philosophy in hemorrhagic shock. ATLS® classification and recommendations on hemorrhagic shock are not helpful because antiphysiological and potentially misleading. Hemorrhagic shock needs to be reclassified in the direction of usefulness and timing of intervention: in particular its assessment and management need to be tailored to physiology.
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