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Mistry N, Hare GM, Shehata N, Kramer RS, Fawzy HF, Baker RA, Carmona P, Saczkowski R, Filipescu D, Alphonsus CS, Rochon A, Gregory AJ, Khanykin B, Leff JD, Mateo E, Karangelis D, Tellez JC, Saha T, Ko DT, Wijeysundera DN, Verma S, Mazer CD. Methemoglobin as a marker of acute anemic stress in cardiac surgery. iScience 2023; 26:107429. [PMID: 37575193 PMCID: PMC10415918 DOI: 10.1016/j.isci.2023.107429] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/01/2023] [Accepted: 07/17/2023] [Indexed: 08/15/2023] Open
Abstract
Biological evidence supports plasma methemoglobin as a biomarker for anemia-induced tissue hypoxia. In this translational planned substudy of the multinational randomized controlled transfusion thresholds in cardiac surgery (TRICS-III) trial, which included adults undergoing cardiac surgery requiring cardiopulmonary bypass with a moderate-to-high risk of death, we investigated the relationship between perioperative hemoglobin concentration (Hb) and methemoglobin; and evaluated its association with postoperative outcomes. The primary endpoint was a composite of death, myocardial infarction, stroke, and severe acute kidney injury at 28 days. We observe weak non-linear associations between decreasing Hb and increasing methemoglobin, which were strongest in magnitude at the post-surgical time point. Increased levels of post-surgical methemoglobin were associated with a trend toward an elevated risk for stroke and exploratory neurological outcomes. Our generalizable study demonstrates post-surgical methemoglobin may be a marker of anemia-induced organ injury/dysfunction, and may have utility for guiding personalized approaches to anemia management. Clinicaltrials.gov registration NCT02042898.
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Affiliation(s)
- Nikhil Mistry
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Gregory M.T. Hare
- Department of Anesthesia, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Nadine Shehata
- Division of Hematology, Sinai Health System, Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Robert S. Kramer
- Maine Medical Center Cardiovascular Institute, Portland, ME, USA
| | - Hosam F. Fawzy
- Department of Cardiothoracic Surgery, Faculty of Medicine, University of Tanta, Tanta, Egypt
| | - Robert A. Baker
- Cardiac Surgery Research and Perfusion, Flinders University and Flinders Medical Centre, Adelaide, SA, Australia
| | - Paula Carmona
- Cardiovascular-Anesthesia and Intensive Care. University Hospital La Fe, Valencia, Spain
| | - Richard Saczkowski
- Department of Cardiac Sciences, Perfusion Services, Kelowna General Hospital, Kelowna, BC, Canada
| | - Daniela Filipescu
- University of Medicine and Pharmacy Carol Davila, Emergency Institute for Cardiovascular Diseases “Prof. Dr. C.C. Iliescu”, Bucharest, Romania
| | - Christella S. Alphonsus
- Department of Anaesthesia and Perioperative Medicine, Faculty of Health Sciences, University of Cape Town and Groote Schuur Hospital, Cape Town, South Africa
| | | | - Alexander J. Gregory
- Department of Anesthesiology, Perioperative and Pain Medicine and Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Boris Khanykin
- Cardiothoracic Anesthesiology Department, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Jonathan D. Leff
- Montefiore-Einstein Center for Heart and Vascular Care, New York City, NY, USA
| | - Eva Mateo
- Hospital General Universitario de València, València, Spain
| | - Dimos Karangelis
- Department of Cardiothoracic Surgery, Democritus University of Thrace, Alexandroupolis, Greece
| | | | - Tarit Saha
- Department of Anesthesiology and Perioperative Medicine, Kingston General Hospital, Kingston, ON, Canada
| | - Dennis T. Ko
- Schulich Heart Program, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
- Institute of Health Policy Management, and Evaluation, University of Toronto, Toronto, ON, Canada
- ICES, Toronto, ON, Canada
| | - Duminda N. Wijeysundera
- Department of Anesthesia, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON, Canada
- Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
- Institute of Health Policy Management, and Evaluation, University of Toronto, Toronto, ON, Canada
- ICES, Toronto, ON, Canada
| | - Subodh Verma
- Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
- Division of Cardiac Surgery, St. Michael’s Hospital, Department of Surgery, University of Toronto, Toronto, ON, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - C. David Mazer
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia, St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Li Ka Shing Knowledge Institute of St. Michael’s Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
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2
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Köhler D, Voshaar T, Stais P, Haidl P, Dellweg D. Hypoxische, anämische und kardial bedingte Hypoxämie: Wann beginnt die Hypoxie im Gewebe? Dtsch Med Wochenschr 2023; 148:475-482. [PMID: 36990120 DOI: 10.1055/a-2007-5450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
ZusammenfassungBei einer Hypoxämie ist oft der Sauerstoffgehalt noch im unteren Normbereich, sodass keine
Hypoxie im Gewebe vorliegt. Wird die Hypoxie-Schwelle im Gewebe bei einer hypoxisch, anämisch
und auch kardial bedingten Hypoxämie erreicht, kommt es im Zellstoffwechsel, unabhängig von
der Genese, zu identischen Gegenregulationen. Im klinischen Alltag wird diese
pathophysiologische Tatsache mitunter ignoriert, obwohl je nach Hypoxämie-Ursache die
Beurteilung und die Therapie stark unterschiedlich sind. Während für die anämische Hypoxämie
restriktive und allgemein akzeptierte Regeln in den Transfusionsrichtlinien festgelegt sind,
wird bei einer hypoxischen Hypoxie früh die Indikation zu einer meist invasiven Beatmung
gestellt. Die klinische Beurteilung und Indikationsstellung fokussiert dabei auf die Parameter
Sauerstoffsättigung, Sauerstoffpartialdruck und Oxygenierungsindex. Während der
Corona-Pandemie sind Fehlinterpretationen der Pathophysiologie sichtbar geworden und haben
vermutlich zu überflüssigen Intubationen geführt. Für die Behandlung einer hypoxischen Hypoxie
mittels invasiver Beatmung aber gibt es keine Evidenz. Im vorliegenden Review wird auf die
Pathophysiologie der verschiedenen Hypoxieursachen unter besonderer Berücksichtigung der
Intubation und Beatmung auf der Intensivstation eingegangen.
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Abstract
Pericytes, attached to the surface of capillaries, play an important role in regulating local blood flow. Using optogenetic tools and genetically encoded reporters in conjunction with confocal and multiphoton imaging techniques, the 3D structure, anatomical organization, and physiology of pericytes have recently been the subject of detailed examination. This work has revealed novel functions of pericytes and morphological features such as tunneling nanotubes in brain and tunneling microtubes in heart. Here, we discuss the state of our current understanding of the roles of pericytes in blood flow control in brain and heart, where functions may differ due to the distinct spatiotemporal metabolic requirements of these tissues. We also outline the novel concept of electro-metabolic signaling, a universal mechanistic framework that links tissue metabolic state with blood flow regulation by pericytes and vascular smooth muscle cells, with capillary KATP and Kir2.1 channels as primary sensors. Finally, we present major unresolved questions and outline how they can be addressed.
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Affiliation(s)
- Thomas A Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Guiling Zhao
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ashwini Hariharan
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - W Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA; ,
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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4
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Suppan E, Pichler G, Binder-Heschl C, Schwaberger B, Urlesberger B. Three Physiological Components That Influence Regional Cerebral Tissue Oxygen Saturation. Front Pediatr 2022; 10:913223. [PMID: 35769216 PMCID: PMC9234387 DOI: 10.3389/fped.2022.913223] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 05/09/2022] [Indexed: 11/17/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) measurement of regional cerebral tissue oxygen saturation (rcStO2) has become a topic of high interest in neonatology. Multiple studies have demonstrated that rcStO2 measurements are feasible in the delivery room during immediate transition and resuscitation as well as after admission to the neonatal intensive care unit. Reference ranges for different gestational ages, modes of delivery, and devices have already been published. RcStO2 reflects a mixed tissue saturation, composed of arterial (A), venous (V), and capillary signals, derived from small vessels within the measurement compartment. The A:V signal ratio fluctuates based on changes in oxygen delivery and oxygen consumption, which enables a reliable trend monitoring of the balance between these two parameters. While the increasing research evidence supports its use, the interpretation of the absolute values of and trends in rcStO2 is still challenging, which halts its routine use in the delivery room and at the bedside. To visualize the influencing factors and improve the understanding of rcStO2 values, we have created a flowchart, which focuses on the three major physiological components that affect rcStO2: oxygen content, circulation, and oxygen extraction. Each of these has its defining parameters, which are discussed in detail in each section.
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Affiliation(s)
- Ena Suppan
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Gerhard Pichler
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Corinna Binder-Heschl
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Bernhard Schwaberger
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Berndt Urlesberger
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
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5
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Hu Q, Nelson TJ, Seymour RS. Morphology of the nutrient artery and its foramen in relation to femoral bone perfusion rates of laying and non-laying hens. J Anat 2022; 240:94-106. [PMID: 34405399 PMCID: PMC8655192 DOI: 10.1111/joa.13535] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 01/19/2023] Open
Abstract
If arteries penetrate bones through foramina, regional artery blood flow rates can be estimated from the foramen sizes. Femoral bone blood flow rates estimated from nutrient foramen sizes were previously not absolute, but only a relative blood flow index (Qi ), because the size relationship between the foramen and the occupying artery was unknown. The current study used vascular contrast and micro-computerized tomographic scanning to investigate femoral nutrient foramen and nutrient artery sizes in three groups of sub-adult chickens (non-laying hens, laying hens, and roosters) of similar ages. The results indicate that the cross-sectional area of the nutrient artery lumen occupies approximately 20.2 ± 4.1% of the foramen for femora with only one foramen. Artery lumen size is significantly correlated with foramen size. Vascular contrast imaging is capable of estimating blood flow rates through nutrient arteries, as blood flow rates estimated from artery lumen casts are similar to blood flow rates measured by infusion of fluorescent-labeled microspheres. Laying hens tend to have higher nutrient artery perfusion rates than non-laying hens, probably due to extra oxygen and calcium requirements for eggshell production, although the calculated blood flow difference was not statistically significant. Histological embedding and sectioning along with vascular contrast imaging reveal variable nutrient foramen morphology and nutrient artery location among femora with more than one nutrient foramen.
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Affiliation(s)
- Qiaohui Hu
- School of Biological SciencesUniversity of AdelaideAdelaideSouth AustraliaAustralia
| | - Thomas J. Nelson
- School of Biological SciencesUniversity of AdelaideAdelaideSouth AustraliaAustralia
| | - Roger S. Seymour
- School of Biological SciencesUniversity of AdelaideAdelaideSouth AustraliaAustralia
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6
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Elsayed YN, Dakshinamurti S. Titration of inspired oxygen in preterm infants with hypoxemic respiratory failure using near-infrared spectroscopy and pulse oximetry: A new approach. Pediatr Pulmonol 2021; 56:3870-3878. [PMID: 34549553 DOI: 10.1002/ppul.25673] [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] [Received: 05/11/2021] [Revised: 07/13/2021] [Accepted: 08/25/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND Titration of inspired oxygen is a challenge in preterm infants with hypoxemic respiratory failure (HRF). Monitoring of brain oxygen by near-infrared spectroscopy (NIRS) has been proven to minimize the burden of hyperoxia and hypoxemia; with a better understanding of cerebral autoregulation, integrating NIRS and pulse oximetry for titrating inspired oxygen in preterm infants is a novel approach. METHODS We studied the impact of integrated monitoring of oxygen saturation by pulse oximetry (SpO2 ) and cerebral regional tissue oxygen (crRTO) by NIRS during a stepwise oxygen reduction test (ORT) on reducing oxygen requirement in preterm infants with HRF. The correlation between SpO2 with crRTO, and fractional oxygen extraction (FOE) was assessed, concordance levels (r > 0.5) were determined during the assessment period and were considered as a sign of impaired autoregulation. The primary outcome was the achievement of significantly lower FiO2 at 72 h after the start of the integrated monitoring. RESULTS A total of 38 preterm infants were included, 27 had normal cerebral autoregulation (CAR) (Group 1) in whom SpO2 was poorly correlating with crRTO with (r < 0.5) and had a significantly greater percentage of reduction below baseline in FiO2 (mean: 34%). Eleven infants had impaired CAR (Group 2) with SpO2 significantly correlating with crRTO (r > 0.5) and had a linear trend of FOE inverse to SpO2 and crRTO; this was considered as an arterial saturation dependent oxygen delivery (SadDO2 ). CONCLUSION Integrated monitoring of preterm infants by SpO2 and crRTO was associated with easier weaning of oxygen with less burden of both hyperoxia and hypoxemia.
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Affiliation(s)
- Yasser N Elsayed
- Section of Neonatology, University of Manitoba, Winnipeg, Canada
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7
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Hu Q, Nelson TJ, Seymour RS. Regional femoral bone blood flow rates in laying and non-laying chickens estimated with fluorescent microspheres. J Exp Biol 2021; 224:271048. [PMID: 34312667 PMCID: PMC8407662 DOI: 10.1242/jeb.242597] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 07/19/2021] [Indexed: 01/17/2023]
Abstract
The metabolic rate of vertebrate bone tissue is related to bone growth, repair and homeostasis, which are all dependent on life stage. Bone metabolic rate is difficult to measure directly, but absolute blood flow rate () should reflect local tissue oxygen requirements. A recent ‘foramen technique’ has derived an index of blood flow rate () by measuring nutrient foramen sizes of long bones. is assumed to be proportional to ; however, the assumption has never been tested. This study used fluorescent microsphere infusion to measure femoral bone in anaesthetized non-laying hens, laying hens and roosters. Mean mass-specific cardiac output was 338±38 ml min−1 kg−1, and the two femora received 0.63±0.10% of this. Laying hens had higher wet bone mass-specific to femora (0.23±0.09 ml min−1 g−1) than the non-laying hens (0.12±0.06 ml min−1 g−1) and roosters (0.14±0.04 ml min−1 g−1), presumably associated with higher bone calcium mobilization during eggshell production. Estimated metabolic rate of femoral bone was 0.019 ml O2 min−1 g−1. Femoral increased significantly with body mass, but was not correlated with nutrient foramen radius (r), probably because of a narrow range in foramen radius. Over all 18 chickens, femoral shaft was 1.07±0.30 ml min−1 mm−1. Mean in chickens was significantly higher than predicted by an allometric relationship for adult cursorial bird species, possibly because the birds were still growing. Summary: Femoral bone blood flow, measured using fluorescent microspheres, is approximately two times higher in laying hens than in non-laying hens and roosters. Blood flow values were related to foramen sizes.
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Affiliation(s)
- Qiaohui Hu
- School of Biological Sciences , University of Adelaide, Adelaide, SA 5005, Australia
| | - Thomas J Nelson
- School of Biological Sciences , University of Adelaide, Adelaide, SA 5005, Australia
| | - Roger S Seymour
- School of Biological Sciences , University of Adelaide, Adelaide, SA 5005, Australia
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8
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Henriksen OM, Gjedde A, Vang K, Law I, Aanerud J, Rostrup E. Regional and interindividual relationships between cerebral perfusion and oxygen metabolism. J Appl Physiol (1985) 2021; 130:1836-1847. [PMID: 33830816 DOI: 10.1152/japplphysiol.00939.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Quantitative measurements of resting cerebral blood flow (CBF) and metabolic rate of oxygen (CMRO2) show large between-subject and regional variability, but the relationships between CBF and CMRO2 measurements regionally and globally are not fully established. Here, we investigated the between-subject and regional associations between CBF and CMRO2 measures with independent and quantitative PET techniques. We included resting CBF and CMRO2 measurements from 50 healthy volunteers (aged 22-81 yr), and calculated the regional and global values of oxygen delivery (Do2) and oxygen extraction fraction (OEF). Linear mixed-model analysis showed that CBF and CMRO2 measurements were closely associated regionally, but no significant between-subject association could be demonstrated, even when adjusting for arterial Pco2 and hemoglobin concentration. The analysis also showed regional differences of OEF, reflecting variable relationship between Do2 and CMRO2, resulting in lower estimates of OEF in thalami, brainstem, and mesial temporal cortices and higher estimates of OEF in occipital cortex. In the present study, we demonstrated no between-subject association of quantitative measurements of CBF and CMRO2 in healthy subjects. Thus, quantitative measurements of CBF did not reflect the underlying between-subject variability of oxygen metabolism measures, mainly because of large interindividual OEF variability not accounted for by Pco2 and hemoglobin concentration.NEW & NOTEWORTHY Using quantitative PET-measurements in healthy human subjects, we confirmed a regional association of CBF and CMRO2, but did not find an association of these values across subjects. This suggests that subjects have an individual coupling between perfusion and metabolism and shows that absolute perfusion measurements does not serve as a surrogate measure of individual measures of oxygen metabolism. The analysis further showed smaller, but significant regional differences of oxygen extraction fraction at rest.
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Affiliation(s)
- Otto M Henriksen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Albert Gjedde
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Translational Neuropsychiatry Unit, Aarhus University and University Hospital, Aarhus, Denmark.,Department of Nuclear Medicine and PET Centre, Aarhus University and University Hospital, Aarhus, Denmark
| | - Kim Vang
- Department of Nuclear Medicine and PET Centre, Aarhus University and University Hospital, Aarhus, Denmark
| | - Ian Law
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Joel Aanerud
- Department of Nuclear Medicine and PET Centre, Aarhus University and University Hospital, Aarhus, Denmark
| | - Egill Rostrup
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark.,Mental Health Center Glostrup, University of Copenhagen, Copenhagen, Denmark
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9
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Abstract
Oxygen affinity to haemoglobin is indicated by the p50 value (pO2 at 50% O2Hb) and critically determines cellular oxygen availability. Although high Hb-O2 affinity can cause tissue hypoxia under conditions of well O2 saturated blood, individual differences in p50 are commonly not considered in clinical routine. Here, we investigated the diversity in Hb-O2 affinity in the context of physiological relevance. Oxyhaemoglobin dissociation curves (ODCs) of 60 volunteers (18–40 years, both sexes, either endurance trained or untrained) were measured at rest and after maximum exercise (VO2max) test. At rest, p50 values of all participants ranged over 7 mmHg. For comparison, right shift of ODC after VO2max test, representing the maximal physiological range to release oxygen to the tissue, indicated a p50 difference of up to 10 mmHg. P50 at rest differs significantly between women and men, with women showing lower Hb-O2 affinity that is determined by higher 2,3-BPG and BPGM levels. Regular endurance exercise did not alter baseline Hb-O2 affinity. Thus, p50 diversity is already high at baseline level and needs to be considered under conditions of impaired tissue oxygenation. For fast prediction of Hb-O2 affinity by blood gas analysis, only venous but not capillary blood samples can be recommended.
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10
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Beck JR, Holt DW, Chan C, Fung K, Patton-Rivera K, Mullin D, Takeda K, Takayama H. Discussion: can upper extremity (deltoid) near infrared spectroscopy be used to assess cerebral tissue bed saturation on femorally cannulated veno-arterial extracorporeal membrane oxygenation patients? Perfusion 2020; 36:190-199. [PMID: 32579084 DOI: 10.1177/0267659120906769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Continuous cerebral tissue saturation monitoring with near infrared spectroscopy may help clinicians identify cerebral desaturation early; however, patients have reported discomfort from near infrared spectroscopy monitoring pads on the forehead. This study aims to compare upper extremity near infrared spectroscopy monitoring to cerebral near infrared spectroscopy monitoring to assess its viability as a surrogate for cerebral saturation. A retrospective analysis of 10 femorally cannulated veno-arterial extracorporeal membrane oxygenation patients was performed comparing left (L) and right (R) upper extremity (deltoid) near infrared spectroscopy monitoring to cerebral near infrared spectroscopy monitoring (n = 20 data sets, 10 left and 10 right) and right radial blood gasses. Deltoid and cerebral near infrared spectroscopy values were recorded every 15 minutes for at least 24 hours when possible, were plotted on scatter grams, and were analyzed using Pearson product-moment coefficient (r). Based on the concept of covariance, a moderate-good relationship r = 0.50-0.75 was noted in 10% (n = 2) of the study group. A fair relationship r = 0.25-0.50 was noted in 50% (n = 10), and little or no relationship was noted in 40% (n = 8). None of the study group displayed a good to excellent relationship (r = 0.75 or above). In addition, coefficient of multiple determination for multiple regression R2 was calculated and strong fit of the regression line was not noted. Although cerebral near infrared spectroscopy monitoring has been extremely helpful in identifying low cerebral tissue saturation on veno-arterial extracorporeal membrane oxygenation patients, the use of upper extremity (peripheral deltoid) tissue monitoring does not provide adequate correlation and should not be used as a surrogate to cerebral monitoring.
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Affiliation(s)
- James R Beck
- Division of Cardiothoracic Surgery and Clinical Perfusion, Department of Surgery, New York Presbyterian Hospital, Columbia University Irving Medical Center, New York, NY, USA
| | - David W Holt
- Clinical Perfusion Education, University of Nebraska Medical Center, Omaha, NE, USA
| | - Christine Chan
- Division of Cardiothoracic Surgery and Clinical Perfusion, Department of Surgery, New York Presbyterian Hospital, Columbia University Irving Medical Center, New York, NY, USA
| | - Kenmond Fung
- Division of Cardiothoracic Surgery and Clinical Perfusion, Department of Surgery, New York Presbyterian Hospital, Columbia University Irving Medical Center, New York, NY, USA
| | - Killian Patton-Rivera
- Division of Cardiothoracic Surgery and Clinical Perfusion, Department of Surgery, New York Presbyterian Hospital, Columbia University Irving Medical Center, New York, NY, USA
| | - Dana Mullin
- Division of Cardiothoracic Surgery and Clinical Perfusion, Department of Surgery, New York Presbyterian Hospital, Columbia University Irving Medical Center, New York, NY, USA
| | - Koji Takeda
- Division of Cardiothoracic Surgery and Clinical Perfusion, Department of Surgery, New York Presbyterian Hospital, Columbia University Irving Medical Center, New York, NY, USA
| | - Hiroo Takayama
- Division of Cardiothoracic Surgery and Clinical Perfusion, Department of Surgery, New York Presbyterian Hospital, Columbia University Irving Medical Center, New York, NY, USA
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12
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ATP- and voltage-dependent electro-metabolic signaling regulates blood flow in heart. Proc Natl Acad Sci U S A 2020; 117:7461-7470. [PMID: 32170008 DOI: 10.1073/pnas.1922095117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Local control of blood flow in the heart is important yet poorly understood. Here we show that ATP-sensitive K+ channels (KATP), hugely abundant in cardiac ventricular myocytes, sense the local myocyte metabolic state and communicate a negative feedback signal-correction upstream electrically. This electro-metabolic voltage signal is transmitted instantaneously to cellular elements in the neighboring microvascular network through gap junctions, where it regulates contractile pericytes and smooth muscle cells and thus blood flow. As myocyte ATP is consumed in excess of production, [ATP]i decreases to increase the openings of KATP channels, which biases the electrically active myocytes in the hyperpolarization (negative) direction. This change leads to relative hyperpolarization of the electrically connected cells that include capillary endothelial cells, pericytes, and vascular smooth muscle cells. Such hyperpolarization decreases pericyte and vascular smooth muscle [Ca2+]i levels, thereby relaxing the contractile cells to increase local blood flow and delivery of nutrients to the local cardiac myocytes and to augment ATP production by their mitochondria. Our findings demonstrate the pivotal roles of local cardiac myocyte metabolism and KATP channels and the minor role of inward rectifier K+ (Kir2.1) channels in regulating blood flow in the heart. These findings establish a conceptually new framework for understanding the hugely reliable and incredibly robust local electro-metabolic microvascular regulation of blood flow in heart.
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13
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Hu Q, Nelson TJ, Seymour RS. Bone foramen dimensions and blood flow calculation: best practices. J Anat 2019; 236:357-369. [PMID: 31713844 DOI: 10.1111/joa.13106] [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] [Accepted: 09/18/2019] [Indexed: 02/06/2023] Open
Abstract
Some blood vessels enter bones through foramina, leaving the size of the foramen as a gauge for estimating the rate of blood flow and hence the metabolic rate of the supplied tissues. Foramen dimensions have been measured using varied methods in previous foramen studies, to relate regional blood flows with associated physiological processes. With the increasing interests in this 'foramen technique', standard methods with minimized measurement errors are therefore required. This study provides details of microphotographic and micro-computerized tomographic methods, and introduces a new alternative method, which uses impression material to measure foramen dimensions. The three methods are compared and the results indicate that all of them are capable of obtaining precise and accurate foramen dimension values, although they all have limitations. A microphotograph of the external opening is suggested to be the standard method because of its ease of use, but the alternative methods provide more detailed information on foramen shape. If the foramen is mainly occupied by one artery, blood flow rates can be calculated from foramen size and artery wall-lumen ratio, which is evaluated from the literature survey in this study. If veins or nerves also penetrate the foramen, a relative index of blood flow rate is nevertheless possible for comparative purposes.
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Affiliation(s)
- Qiaohui Hu
- School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Thomas J Nelson
- School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Roger S Seymour
- School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
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14
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Affiliation(s)
- Domenico Calcaterra
- Department of SurgeryUniversity of Minnesota Medical SchoolMinneapolis Minnesota
| | - Marco Ricci
- Department of SurgeryUniversity of IowaIowa City Iowa
| | - Aryeh Shander
- Department of AnesthesiologyEnglewood Hospital and Medical CenterEnglewood New Jersey
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15
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Dhir A, Tempe DK. Anemia and Patient Blood Management in Cardiac Surgery—Literature Review and Current Evidence. J Cardiothorac Vasc Anesth 2018; 32:2726-2742. [DOI: 10.1053/j.jvca.2017.11.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Indexed: 12/24/2022]
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16
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Brijs J, Gräns A, Hjelmstedt P, Sandblom E, van Nuland N, Berg C, Axelsson M. In vivo aerobic metabolism of the rainbow trout gut and the effects of an acute temperature increase and stress event. ACTA ACUST UNITED AC 2018; 221:jeb.180703. [PMID: 29798844 DOI: 10.1242/jeb.180703] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/21/2018] [Indexed: 12/31/2022]
Abstract
The fish gut is responsible for numerous potentially energetically costly processes, yet little is known about its metabolism. Here, we provide the first in vivo measurements of aerobic metabolism of the gut in a teleost fish by measuring gut blood flow, as well as arterial and portal venous oxygen content. At 10°C, gut oxygen uptake rate was 4.3±0.5 ml O2 h-1 kg-1 (∼11% of whole-animal oxygen uptake). Following acute warming to 15°C, gut blood flow increased ∼3.4-fold and gut oxygen uptake rate increased ∼3.7-fold (16.0±3.3 ml O2 h-1 kg-1), now representing ∼25% of whole-animal oxygen uptake. Although gut blood flow decreased following an acute stress event at 15°C, gut oxygen uptake remained unchanged as a result of a ∼2-fold increase in oxygen extraction. The high metabolic thermal sensitivity of the gut could have important implications for the overall aerobic capacity and performance of fish in a warming world and warrants further investigation.
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Affiliation(s)
- Jeroen Brijs
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara SE-532 23, Sweden.,Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara SE-532 23, Sweden
| | - Per Hjelmstedt
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara SE-532 23, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden
| | - Nicole van Nuland
- Institute for Life Sciences and Chemistry, University of Applied Sciences, 3584 CH Utrecht, The Netherlands
| | - Charlotte Berg
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara SE-532 23, Sweden
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg SE-405 30, Sweden
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17
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Haley AP, Oleson S, Pasha E, Birdsill A, Kaur S, Thompson J, Tanaka H. Phenotypic heterogeneity of obesity-related brain vulnerability: one-size interventions will not fit all. Ann N Y Acad Sci 2018; 1428:89-102. [PMID: 29741211 DOI: 10.1111/nyas.13673] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 02/10/2018] [Accepted: 02/17/2018] [Indexed: 01/07/2023]
Abstract
Intact memory and problem solving are key to functional independence and quality of life in older age. Considering the unprecedented demographic shift toward a greater number of older adults than children in the United States in the next few decades, it is critically important for older adults to maintain work productivity and functional independence for as long as possible. Implementing early interventions focused on modifiable risk factors for cognitive decline at midlife is a strategy with the highest chance of success at present, bearing in mind the current lack of dementia cures. We present a selective, narrative review of evidence linking nutrition, body composition, vascular health, and brain function in midlife to highlight the phenotypic heterogeneity of obesity-related brain vulnerability and to endorse the development of individually tailored lifestyle modification plans for primary prevention of cognitive decline.
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Affiliation(s)
- Andreana P Haley
- Department of Psychology, The University of Texas at Austin, Austin, Texas.,Imaging Research Center, The University of Texas at Austin, Austin, Texas
| | - Stephanie Oleson
- Department of Psychology, The University of Texas at Austin, Austin, Texas
| | - Evan Pasha
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, Texas
| | - Alex Birdsill
- Department of Psychology, The University of Texas at Austin, Austin, Texas
| | - Sonya Kaur
- Department of Psychology, The University of Texas at Austin, Austin, Texas
| | - Janelle Thompson
- Department of Psychology, The University of Texas at Austin, Austin, Texas
| | - Hirofumi Tanaka
- Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, Texas
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18
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Hu Q, Nelson TJ, Snelling EP, Seymour RS. Femoral bone perfusion through the nutrient foramen during growth and locomotor development of western grey kangaroos ( Macropus fuliginosus). ACTA ACUST UNITED AC 2018; 221:jeb.168625. [PMID: 29361586 DOI: 10.1242/jeb.168625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 12/14/2017] [Indexed: 11/20/2022]
Abstract
The nutrient artery passes through the nutrient foramen on the shaft of the femur and supplies more than half of the total blood flow to the bone. Assuming that the size of the nutrient foramen correlates with the size of the nutrient artery, an index of blood flow rate (Qi) can be calculated from nutrient foramen dimensions. Interspecific Qi is proportional to locomotor activity levels in adult mammals, birds and reptiles. However, no studies have yet estimated intraspecific Qi to test for the effects of growth and locomotor development on bone blood flow requirements. In this study, we used micro-CT and medical CT scanning to measure femoral dimensions and foramen radius to calculate femoral Qi during the in-pouch and post-pouch life stages of western grey kangaroos (Macropus fuliginosus) weighing 5.7 g to 70.5 kg and representing a 12,350-fold range in body mass. A biphasic scaling relationship between Qi and body mass was observed (breakpoint at ca. 1-5 kg body mass right before permanent pouch exit), with a steep exponent of 0.96±0.09 (95% CI) during the in-pouch life stage and a statistically independent exponent of -0.59±0.90 during the post-pouch life stage. In-pouch joeys showed Qi values that were 50-100 times higher than those of adult diprotodont marsupials of the same body mass, but gradually converged with them as post-pouch adults. Bone modelling during growth appears to be the main determinant of femoral bone blood flow during in-pouch development, whereas bone remodelling for micro-fracture repair due to locomotion gradually becomes the main determinant when kangaroos leave the pouch and become more active.
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Affiliation(s)
- Qiaohui Hu
- Department of Ecology and Environmental Science, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Thomas J Nelson
- Department of Ecology and Environmental Science, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Edward P Snelling
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, Gauteng 2193, South Africa
| | - Roger S Seymour
- Department of Ecology and Environmental Science, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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Watts JA, Kelly FR, Bauch TD, Murgo JP, Rubal BJ. Rest and exercise hemodynamic and metabolic findings in active duty soldiers referred for cardiac catheterization to exclude heart disease: Insights from past invasive cardiopulmonary exercise testing using multisensor high fidelity catheters. Catheter Cardiovasc Interv 2018; 91:35-46. [PMID: 28805343 DOI: 10.1002/ccd.27101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 02/09/2017] [Accepted: 03/25/2017] [Indexed: 11/10/2022]
Abstract
OBJECTIVE This study describes results of iCPET from the past, which used submaximal stress and multisensor high-fidelity catheters to exclude heart disease in a unique population of young adults. BACKGROUND There has been resurgence in comprehensive hemodynamic evaluation of complex cardiovascular patients. Although dynamic assessments during cardiac catheterization have become commonplace, there remains limited information regarding left and right heart hemodynamic changes during supine exercise in young adults. METHODS The study population was derived from a retrospective review of catheterization records at Brooke Army Medical Center for active duty patients (ages: 19-40 years) in whom hemodynamic waveforms were obtained with multisensor high-fidelity catheters and supine exercise testing (53.1 ± 12.6 watts) and angiography performed to exclude heart disease. We report findings from 41 males and 1 female (ages: 19-40 years) found free of heart disease. RESULTS Submaximal exercise was associated with ≈ fourfold (P < 0.001) increase in minute ventilation (VE), O2 consumption (VO2 ) and carbon dioxide production (VCO2 ). VE/VCO2 ratio decreased (-16.8 ± 13.9%, P < 0.001) and VE/VCO2 slope was 22.6 ± 0.6 (±SE). Cardiac index (CI) increased with VO2 (ΔCI/ΔVO2 slope = 7.6 ± 2.2). Heart rate increased nearly 10 bpm per 100 mL O2 /min/M2 , whereas, changes in stroke volume were more variable. Pulmonary artery (PA) saturations fell from 77 to 55% (P < 0.001). No change was noted in mean right atrial pressures; PA pressures increased ≈10 mm Hg (P < 0.001). Pulmonary capillary wedge and left ventricular end-diastolic pressures increased ≈2 mm Hg (P < 0.001) but variability noted between individuals. CONCLUSION This study provides insight into past practices of invasive cardiopulmonary testing and furthers the understanding of metabolic and hemodynamic changes in a young population during supine submaximal exercise. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- James A Watts
- Cardiology Service, Brooke Army Medical Center, Fort Sam Houston, Texas
| | - Faith R Kelly
- Cardiology Service, Brooke Army Medical Center, Fort Sam Houston, Texas
| | - Terry D Bauch
- Geisinger Heart and Vascular Institute, Danville, Pennsylvania
| | - Joseph P Murgo
- University of Texas Health Science Center at San Antonio and Audie Murphy V.A. Memorial Hospital, San Antonio, Texas
| | - Bernard J Rubal
- Cardiology Service, Brooke Army Medical Center, Fort Sam Houston, Texas
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20
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Goonasekera CDA, Carcillo JA, Deep A. Oxygen Delivery and Oxygen Consumption in Pediatric Fluid Refractory Septic Shock During the First 42 h of Therapy and Their Relationship to 28-Day Outcome. Front Pediatr 2018; 6:314. [PMID: 30406065 PMCID: PMC6206202 DOI: 10.3389/fped.2018.00314] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/03/2018] [Indexed: 12/16/2022] Open
Abstract
Background: In septic shock, both oxygen delivery (DO2) and oxygen consumption (VO2) are dysfunctional. The current therapeutic regimens are geared to normalize global oxygen delivery (DO2) to tissues via goal directed therapies but mortality remains high at 10-20%. Methods: We studied cardiac index (CI), systemic vascular resistance index (SVRI), central venous oxygen saturation (ScvO2), central venous pressure (CVP), peripheral oxygen saturation (SpO2), mean blood pressure (MBP), body temperature, blood lactate, base excess and hemoglobin concentration (Hb) in a cohort of children admitted in "fluid-refractory" severe septic shock to pediatric intensive care, over 4.5-years. We calculated their 6 h global oxygen delivery (DO2) and global oxygen consumption (VO2) over the first 42 h and looked at factors associated with VO2/DO2 ratio (i.e., global oxygen extraction, gO2ER) and 28-day mortality. Results: Sixty-two children mean age (SD) 7.19 (5.44) years were studied. Fifty-seven (93%) children were sedated and mechanically ventilated and all received adrenaline or noradrenaline or both and added milrinone in 6 (9.6%). At 28 days, 9 (14.5%) were dead. The global oxygen extraction ratio (gO2ER) was consistently lower amongst the survivors and independently predicted mortality (ROC AUC = 0.75). A lactate level of 4 mmol/l or above, when associated with a concurrent metabolic acidosis predicted mortality with a sensitivity of 100% (95% CI 90.5-100) and a specificity of 67.7% (95% CI 62.2-72.9). A gO2ER of 0.48 or above on admission to the PICU was associated with death with a 66.7% sensitivity (95%CI 29.9-92.5) and 90.5% specificity (95%CI 79.3-96.8). A global O2ER of >0.48 combined with a concurrent blood lactate >4.0 mmol/l at any time within the first 42 h of therapy predicted death with a sensitivity of 63.9% (95% CI, 46.2-79.1) and specificity of 97.8% (95% CI, 95.7-99.0). A radar plot identified MBP-CVP difference, and CI as additional goals of therapy that may offer a survival benefit. Conclusions: Global O2ER of >0.48 with a concurrent blood lactate >4.0 mmol/l in children with metabolic acidosis was an independent factor associated with death in fluid resistant septic shock. Trends of gO2ER seem useful to recognize survivors and non-survivors early in the illness.
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Affiliation(s)
| | - Joseph A Carcillo
- Divison of Pediatric Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Akash Deep
- Paediatric Intensive Care Unit, King's College Hospital, London, United Kingdom
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21
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Chen X, Lin W, Wang C, Chen S, Sheng J, Zeng B, Xu M. In vivo real-time imaging of cutaneous hemoglobin concentration, oxygen saturation, scattering properties, melanin content, and epidermal thickness with visible spatially modulated light. BIOMEDICAL OPTICS EXPRESS 2017; 8:5468-5482. [PMID: 29296481 PMCID: PMC5745096 DOI: 10.1364/boe.8.005468] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/20/2017] [Accepted: 10/24/2017] [Indexed: 05/04/2023]
Abstract
We present the real-time single snapshot multiple frequency demodulation - spatial frequency domain imaging (SSMD-SFDI) platform implemented with a visible digital mirror device that is capable of imaging and monitoring dynamic turbid medium and processes over a large field of view. One challenge in quantitative imaging of biological tissue such as the skin is the complex structure rendering techniques based on homogeneous medium models to fail. To address this difficulty we have also developed a novel method that maps the layered structure to a homogeneous medium for spatial frequency domain imaging. The varying penetration depth of spatially modulated light on its wavelength and modulation frequency is used to resolve the layered structure. The efficacy of the real-time SSMD-SFDI platform and this two-layer model is demonstrated by imaging forearms of 6 healthy subjects under the reactive hyperemia protocol. The results show that our approach not only successfully decouples light absorption by melanin from that by hemoglobin and yields accurate determination of cutaneous hemoglobin concentration and oxygen saturation, but also provides reliable estimation of the scattering properties, the melanin content and the epidermal thickness in real time. Potential applications of our system in imaging skin physiological and functional states, cancer screening, and microcirculation monitoring are discussed at the end.
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Affiliation(s)
- Xinlin Chen
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Weihao Lin
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Chenge Wang
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Shaoheng Chen
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Jing Sheng
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - Bixin Zeng
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
| | - M. Xu
- Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China
- Dept. of Physics, Fairfield University, 1073 North Road, Fairfield, CT 06824, USA
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22
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Maricelli JW, Kagel DR, Bishaw YM, Nelson OL, Lin DC, Rodgers BD. Sexually dimorphic skeletal muscle and cardiac dysfunction in a mouse model of limb girdle muscular dystrophy 2i. J Appl Physiol (1985) 2017; 123:1126-1138. [PMID: 28663375 DOI: 10.1152/japplphysiol.00287.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/22/2017] [Accepted: 06/23/2017] [Indexed: 01/06/2023] Open
Abstract
The fukutin-related protein P448L mutant mouse replicates many pathologies common to limb girdle muscular dystrophy 2i (LGMD2i) and is a potentially strong candidate for relevant drug screening studies. Because striated muscle function remains relatively uncharacterized in this mouse, we sought to identify metabolic, functional and histological metrics of exercise and cardiac performance. This was accomplished by quantifying voluntary exercise on running wheels, forced exercise on respiratory treadmills and cardiac output with echocardiography and isoproterenol stress tests. Voluntary exercise revealed few differences between wild-type and P448L mice. By contrast, peak oxygen consumption (VO2peak) was either lower in P448L mice or reduced with repeated low intensity treadmill exercise while it increased in wild-type mice. P448L mice fatigued quicker and ran shorter distances while expending 2-fold more calories/meter. They also received over 6-fold more motivational shocks with repeated exercise. Differences in VO2peak and resting metabolic rate were consistent with left ventricle dysfunction, which often develops in human LGMD2i patients and was more evident in female P448L mice, as indicated by lower fractional shortening and ejection fraction values and higher left ventricle systolic volumes. Several traditional markers of dystrophinopathies were expressed in P448L mice and were exacerbated by exercise, some in a muscle-dependent manner. These include elevated serum creatine kinase and muscle central nucleation, smaller muscle fiber cross-sectional area and more striated muscle fibrosis. These studies together identified several markers of disease pathology that are shared between P448L mice and human subjects with LGMD2i. They also identified novel metrics of exercise and cardiac performance that could prove invaluable in preclinical drug trials.NEW & NOTEWORTHY Limb-girdle muscular dystrophy 2i is a rare dystroglycanopathy that until recently lacked an appropriate animal model. Studies with the FKRP P448L mutant mouse began assessing muscle structure and function as well as running gait. Our studies further characterize systemic muscle function using exercise and cardiac performance. They identified many markers of respiratory, cardiac and skeletal muscle function that could prove invaluable to better understanding the disease and more importantly, to preclinical drug trials.
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Affiliation(s)
- Joseph W Maricelli
- School of Molecular Biosciences, Washington State University, Pullman, Washington
| | - Denali R Kagel
- School of Molecular Biosciences, Washington State University, Pullman, Washington
| | - Yemeserach M Bishaw
- School of Molecular Biosciences, Washington State University, Pullman, Washington
| | - O Lynne Nelson
- Veterinary Clinical Sciences, Washington State University, Pullman, Washington
| | - David C Lin
- Voiland School of Chemical Engineering and Bioengineering, Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington; and
| | - Buel D Rodgers
- School of Molecular Biosciences, Washington State University, Pullman, Washington; .,Department of Animal Sciences; Washington Center for Muscle Biology, Washington State University, Pullman, Washington
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Ohanyan V, Yin L, Bardakjian R, Kolz C, Enrick M, Hakobyan T, Luli J, Graham K, Khayata M, Logan S, Kmetz J, Chilian WM. Kv1.3 channels facilitate the connection between metabolism and blood flow in the heart. Microcirculation 2017; 24:10.1111/micc.12334. [PMID: 28504408 PMCID: PMC5433265 DOI: 10.1111/micc.12334] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 10/23/2016] [Accepted: 11/01/2016] [Indexed: 12/17/2022]
Abstract
The connection between metabolism and flow in the heart, metabolic dilation, is essential for cardiac function. We recently found redox-sensitive Kv1.5 channels play a role in coronary metabolic dilation; however, more than one ion channel likely plays a role in this process as animals null for these channels still showed limited coronary metabolic dilation. Accordingly, we examined the role of another Kv1 family channel, the energetically linked Kv1.3 channel, in coronary metabolic dilation. We measured myocardial blood flow (contrast echocardiography) during norepinephrine-induced increases in cardiac work (heart rate x mean arterial pressure) in WT, WT mice given correolide (preferential Kv1.3 antagonist), and Kv1.3-null mice (Kv1.3-/- ). We also measured relaxation of isolated small arteries mounted in a myograph. During increased cardiac work, myocardial blood flow was attenuated in Kv1.3-/- and in correolide-treated mice. In isolated vessels from Kv1.3-/- mice, relaxation to H2 O2 was impaired (vs WT), but responses to adenosine and acetylcholine were equivalent to WT. Correolide reduced dilation to adenosine and acetylcholine in WT and Kv1.3-/- , but had no effect on H2 O2 -dependent dilation in vessels from Kv1.3-/- mice. We conclude that Kv1.3 channels participate in the connection between myocardial blood flow and cardiac metabolism.
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Affiliation(s)
- Vahagn Ohanyan
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Liya Yin
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | | | - Christopher Kolz
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Molly Enrick
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Tatevik Hakobyan
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Jordan Luli
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - Kathleen Graham
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | | | - Suzanna Logan
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - John Kmetz
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
| | - William M Chilian
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
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Elsayed YN, Amer R, Seshia MM. The impact of integrated evaluation of hemodynamics using targeted neonatal echocardiography with indices of tissue oxygenation: a new approach. J Perinatol 2017; 37:527-535. [PMID: 28102856 DOI: 10.1038/jp.2016.257] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 12/19/2016] [Accepted: 12/22/2016] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To study the impact of integrated evaluation of hemodynamics (IEH) using targeted neonatal echocardiography, together with regional tissue oxygenation, fractional oxygen extraction using near-infrared spectroscopy on the management of infants with compromised hemodynamics. STUDY DESIGN Retrospective cohort comparison of two groups of infants with compromised hemodynamics. EPOCH 1: did not undergo IEH (January 2012 to March 2014); EPOCH 2: underwent IEH (April 2014 to December 2015). The primary outcome was the time to recovery. RESULTS In all, 340 infants were included; 158 underwent IEH with a median (IQR) of 2 (1 to 3) evaluations per infant. Reasons for assessment included PDA (60%), compromised systemic circulation (14%) and clinically suspected pulmonary hypertension (22%). The time to recovery was shorter in IEH group in patients with compromised systemic circulation median (IQR), 32 h (24 to 63) compared with none IEH group 71 h (36 to 96), pulmonary hypertension 63 h (14.2 to 102) in IEH group compared with 68 h (24 to 240) in none IEH group, there were fewer PDA-related complications in preterm infants with PDA in IEH group. CONCLUSION IEH was associated with shorter time to clinical recovery in infants with compromised hemodynamics.
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Affiliation(s)
- Y N Elsayed
- Section of Neonatology, Department of Paediatrics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - R Amer
- Section of Neonatology, Department of Paediatrics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - M M Seshia
- Section of Neonatology, Department of Paediatrics, University of Manitoba, Winnipeg, Manitoba, Canada
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25
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Chan TN, Venus J. The effect of 30 to 60 minutes of forced-air pre-warming on maintaining intraoperative core temperatures during the first hour post-anesthesia induction in adult patients undergoing general anesthesia: a systematic review protocol. ACTA ACUST UNITED AC 2016; 14:41-8. [PMID: 27532308 DOI: 10.11124/jbisrir-2016-2520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
REVIEW QUESTION/OBJECTIVE The objective of this review is to identify the effectiveness of 30 to 60 minutes of forced-air pre-warming on maintaining intraoperative core temperatures in adult patients undergoing general anesthesia. The review question will focus on the effects of forced-air pre-warming on preventing redistribution hypothermia in the first hour post induction of anesthesia, which is considered the most critical due to an internal core-to-peripheral redistribution of body heat and subsequent loss of heat to the operative room surroundings.
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Affiliation(s)
- Toi Nei Chan
- School of Nurse Anesthesia, Harris College of Nursing and Health Sciences, Texas Christian University, USA
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26
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The Role of Oxidative Stress in Myocardial Ischemia and Reperfusion Injury and Remodeling: Revisited. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:1656450. [PMID: 27313825 PMCID: PMC4897712 DOI: 10.1155/2016/1656450] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 04/11/2016] [Accepted: 05/03/2016] [Indexed: 01/11/2023]
Abstract
Oxidative and reductive stress are dual dynamic phases experienced by the cells undergoing adaptation towards endogenous or exogenous noxious stimulus. The former arises due to the imbalance between the reactive oxygen species production and antioxidant defenses, while the latter is due to the aberrant increase in the reducing equivalents. Mitochondrial malfunction is the common denominator arising from the aberrant functioning of the rheostat that maintains the homeostasis between oxidative and reductive stress. Recent experimental evidences suggest that the maladaptation during oxidative stress could play a pivotal role in the pathophysiology of major cardiovascular diseases such as myocardial infraction, atherosclerosis, and diabetic cardiovascular complications. In this review we have discussed the role of oxidative and reductive stress pathways in the pathogenesis of myocardial ischemia/reperfusion injury and diabetic cardiomyopathy (DCM). Furthermore, we have provided impetus for the development of subcellular organelle targeted antioxidant drug therapy for thwarting the deterioration of the failing myocardium in the aforementioned cardiovascular conditions.
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Wolff CB, Collier DJ, Shah M, Saxena M, Brier TJ, Kapil V, Green D, Lobo M. A Discussion on the Regulation of Blood Flow and Pressure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 876:129-135. [PMID: 26782204 DOI: 10.1007/978-1-4939-3023-4_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Affiliation(s)
- Christopher B Wolff
- Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK.
| | - David J Collier
- Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK
| | - Mussadiq Shah
- Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK
| | - Manish Saxena
- Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK
| | - Timothy J Brier
- Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK
| | - Vikas Kapil
- Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK
- Barts BP Clinic, St Bartholomew's Hospital, Barts Health NHS Trust, London, UK
| | - David Green
- Anaesthetics Department, King's College School of Medicine and Dentistry, London, UK
| | - Melvin Lobo
- Barts and the London School of Medicine and Dentistry, William Harvey Research Institute, Centre for Clinical Pharmacology, William Harvey Heart Centre, Queen Mary University of London, London, UK
- Barts BP Clinic, St Bartholomew's Hospital, Barts Health NHS Trust, London, UK
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Ohanyan V, Yin L, Bardakjian R, Kolz C, Enrick M, Hakobyan T, Kmetz J, Bratz I, Luli J, Nagane M, Khan N, Hou H, Kuppusamy P, Graham J, Fu FK, Janota D, Oyewumi MO, Logan S, Lindner JR, Chilian WM. Requisite Role of Kv1.5 Channels in Coronary Metabolic Dilation. Circ Res 2015. [PMID: 26224794 DOI: 10.1161/circresaha.115.306642] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
RATIONALE In the working heart, coronary blood flow is linked to the production of metabolites, which modulate tone of smooth muscle in a redox-dependent manner. Voltage-gated potassium channels (Kv), which play a role in controlling membrane potential in vascular smooth muscle, have certain members that are redox-sensitive. OBJECTIVE To determine the role of redox-sensitive Kv1.5 channels in coronary metabolic flow regulation. METHODS AND RESULTS In mice (wild-type [WT], Kv1.5 null [Kv1.5(-/-)], and Kv1.5(-/-) and WT with inducible, smooth muscle-specific expression of Kv1.5 channels), we measured mean arterial pressure, myocardial blood flow, myocardial tissue oxygen tension, and ejection fraction before and after inducing cardiac stress with norepinephrine. Cardiac work was estimated as the product of mean arterial pressure and heart rate. Isolated arteries were studied to establish whether genetic alterations modified vascular reactivity. Despite higher levels of cardiac work in the Kv1.5(-/-) mice (versus WT mice at baseline and all doses of norepinephrine), myocardial blood flow was lower in Kv1.5(-/-) mice than in WT mice. At high levels of cardiac work, tissue oxygen tension dropped significantly along with ejection fraction. Expression of Kv1.5 channels in smooth muscle in the null background rescued this phenotype of impaired metabolic dilation. In isolated vessels from Kv1.5(-/-) mice, relaxation to H2O2 was impaired, but responses to adenosine and acetylcholine were normal compared with those from WT mice. CONCLUSIONS Kv1.5 channels in vascular smooth muscle play a critical role in coupling myocardial blood flow to cardiac metabolism. Absence of these channels disassociates metabolism from flow, resulting in cardiac pump dysfunction and tissue hypoxia.
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Affiliation(s)
| | - Liya Yin
- Department of Integrative Medical Sciences
| | - Raffi Bardakjian
- Departement Internal Medicine, Canton Medical Education Foundation
| | | | | | | | - John Kmetz
- Department of Integrative Medical Sciences
| | - Ian Bratz
- Department of Integrative Medical Sciences
| | | | - Masaki Nagane
- Department of Radiology and Medicine, Geisel School of Medicine at Dartmouth College
| | - Nadeem Khan
- Department of Radiology and Medicine, Geisel School of Medicine at Dartmouth College
| | - Huagang Hou
- Department of Radiology and Medicine, Geisel School of Medicine at Dartmouth College
| | - Periannan Kuppusamy
- Department of Radiology and Medicine, Geisel School of Medicine at Dartmouth College
| | | | | | | | - Moses O Oyewumi
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University
| | | | - Jonathan R Lindner
- Division of Cardiovascular Medicine, UHN62, Oregon Health and Science University
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Najafi M, Faraoni D. Hemoglobin optimization and transfusion strategies in patients undergoing cardiac surgery. World J Cardiol 2015; 7:377-382. [PMID: 26225197 PMCID: PMC4513488 DOI: 10.4330/wjc.v7.i7.377] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Revised: 04/07/2015] [Accepted: 05/06/2015] [Indexed: 02/06/2023] Open
Abstract
Although red blood cells (RBCs) transfusion is sometimes associated with adverse reactions, anemia could also lead to increased morbidity and mortality in high-risk patients. For these reasons, the definition of perioperative strategies that aims to detect and treat preoperative anemia, prevent excessive blood loss, and define “optimal” transfusion algorithms is crucial. Although the treatment with preoperative iron and erythropoietin has been recommended in some specific conditions, several controversies exist regarding the benefit-to-risk balance associated with these treatments. Further studies are needed to better define the indications, dosage, and route of administration for preoperative iron with or without erythropoietin supplementation. Although restrictive transfusion strategies in patients undergoing cardiac surgery have been shown to effectively reduce the incidence and the amount of RBCs transfusion without increase in side effects, some high-risk patients (e.g., symptomatic acute coronary syndrome) could benefit from higher hemoglobin concentrations. Despite all efforts made last decade, a significant amount of work remains to be done to improve hemoglobin optimization and transfusion strategies in patients undergoing cardiac surgery.
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Leone M, Asfar P, Radermacher P, Vincent JL, Martin C. Optimizing mean arterial pressure in septic shock: a critical reappraisal of the literature. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:101. [PMID: 25888071 PMCID: PMC4355573 DOI: 10.1186/s13054-015-0794-z] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Guidelines recommend that a mean arterial pressure (MAP) value greater than 65 mm Hg should be the initial blood pressure target in septic shock, but what evidence is there to support this statement? We searched Pubmed and Google Scholar by using the key words 'arterial pressure', 'septic shock', and 'norepinephrine' and retrieved human studies published between 1 January 2000 and 31 July 2014. We identified seven comparative studies: two randomized clinical trials and five observational studies. The results of the literature review suggest that a MAP target of 65 mm Hg is usually sufficient in patients with septic shock. However, a MAP of around 75 to 85 mm Hg may reduce the development of acute kidney injury in patients with chronic arterial hypertension. Because of the high prevalence of chronic arterial hypertension in patients who develop septic shock, this finding is of considerable importance. Future studies should assess interactions between time, fluid volumes administered, and doses of vasopressors.
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Affiliation(s)
- Marc Leone
- Service d'Anesthésie et de Réanimation, Chemin des Bourrely, Hôpital Nord, Assistance Publique-Hôpitaux de Marseille, Aix Marseille Université, 13015, Marseille, France.
| | - Pierre Asfar
- Département de Réanimation Médicale et de Médecine Hyperbare Centre Hospitalier Universitaire Angers; and Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée, CNRS UMR 6214 - INSERM U1083, Université Angers, PRES L'UNAM, 4 Rue Larrey, 49100, Angers, France.
| | - Peter Radermacher
- Institut für Anästhesiologische Pathophysiologie und Verfahrensentwicklung, Universitätsklinikum, Albert-Einstein-Allee 23, 89081, Ulm, Germany.
| | - Jean-Louis Vincent
- Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles, route de Lennik 808, 1070, Brussels, Belgium.
| | - Claude Martin
- Service d'Anesthésie et de Réanimation, Chemin des Bourrely, Hôpital Nord, Assistance Publique-Hôpitaux de Marseille, Aix Marseille Université, 13015, Marseille, France.
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Bailey DP, Smith LR, Chrismas BC, Taylor L, Stensel DJ, Deighton K, Douglas JA, Kerr CJ. Appetite and gut hormone responses to moderate-intensity continuous exercise versus high-intensity interval exercise, in normoxic and hypoxic conditions. Appetite 2015; 89:237-45. [PMID: 25700630 DOI: 10.1016/j.appet.2015.02.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 02/04/2015] [Accepted: 02/13/2015] [Indexed: 02/04/2023]
Abstract
This study investigated the effects of continuous moderate-intensity exercise (MIE) and high-intensity interval exercise (HIIE) in combination with short exposure to hypoxia on appetite and plasma concentrations of acylated ghrelin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1). Twelve healthy males completed four, 2.6 h trials in a random order: (1) MIE-normoxia, (2) MIE-hypoxia, (3) HIIE-normoxia, and (4) HIIE-hypoxia. Exercise took place in an environmental chamber. During MIE, participants ran for 50 min at 70% of altitude-specific maximal oxygen uptake (V˙O2max) and during HIIE performed 6 × 3 min running at 90% V˙O2max interspersed with 6 × 3 min active recovery at 50% V˙O2max with a 7 min warm-up and cool-down at 70% V˙O2max (50 min total). In hypoxic trials, exercise was performed at a simulated altitude of 2980 m (14.5% O2). Exercise was completed after a standardised breakfast. A second meal standardised to 30% of participants' daily energy requirements was provided 45 min after exercise. Appetite was suppressed more in hypoxia than normoxia during exercise, post-exercise, and for the full 2.6 h trial period (linear mixed modelling, p <0.05). Plasma acylated ghrelin concentrations were lower in hypoxia than normoxia post-exercise and for the full 2.6 h trial period (p <0.05). PYY concentrations were higher in HIIE than MIE under hypoxic conditions during exercise (p = 0.042). No differences in GLP-1 were observed between conditions (p > 0.05). These findings demonstrate that short exposure to hypoxia causes suppressions in appetite and plasma acylated ghrelin concentrations. Furthermore, appetite responses to exercise do not appear to be influenced by exercise modality.
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Affiliation(s)
- Daniel P Bailey
- Institute for Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire, Polhill Avenue, Bedford, Bedfordshire MK41 9EA, UK.
| | - Lindsey R Smith
- Institute for Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire, Polhill Avenue, Bedford, Bedfordshire MK41 9EA, UK
| | - Bryna C Chrismas
- Institute for Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire, Polhill Avenue, Bedford, Bedfordshire MK41 9EA, UK
| | - Lee Taylor
- Institute for Sport and Physical Activity Research, Department of Sport Science and Physical Activity, University of Bedfordshire, Polhill Avenue, Bedford, Bedfordshire MK41 9EA, UK
| | - David J Stensel
- School of Sport, Exercise and Health Sciences, Loughborough University, Ashby Road, Loughborough, Leicestershire LE11 3TU, UK
| | - Kevin Deighton
- School of Sport, Exercise and Health Sciences, Loughborough University, Ashby Road, Loughborough, Leicestershire LE11 3TU, UK
| | - Jessica A Douglas
- School of Sport, Exercise and Health Sciences, Loughborough University, Ashby Road, Loughborough, Leicestershire LE11 3TU, UK
| | - Catherine J Kerr
- Department of Sport and Health Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Oxford OX3 OBP, UK
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Wolff CB, Green DW. Clarification of the circulatory patho-physiology of anaesthesia - implications for high-risk surgical patients. Int J Surg 2014; 12:1348-56. [PMID: 25448657 DOI: 10.1016/j.ijsu.2014.10.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 08/21/2014] [Accepted: 10/25/2014] [Indexed: 10/24/2022]
Abstract
The paper examines the effects of anaesthesia on circulatory physiology and their implications regarding improvement in perioperative anaesthetic management. Changes to current anaesthetic practice, recommended recently, such as the use of flow monitoring in high risk patients, are already beginning to have an impact in reducing complications but not mortality [1]. Better understanding of the patho-physiology should help improve management even further. Analysis of selected individual clinical trials has been used to illustrate particular areas of patho-physiology and how changes in practice have improved outcome. There is physiological support for the importance of achieving an appropriate rate of oxygen delivery (DO2), particularly following induction of anaesthesia. It is suggested that ensuring adequate DO2 during anaesthesia will avoid development of oxygen debt and hence obviate the need to induce a high, compensatory, DO2 in the post-operative period. In contrast to the usual assumptions underlying strategies requiring a global increase in blood flow [1] by a stroke volume near maximization strategy, blood flow control actually resides entirely at the tissues not at the heart. This is important as the starting point for understanding failed circulatory control as indicated by 'volume dependency'. Local adjustments in blood flow at each individual organ - auto-regulation - normally ensure the appropriate local rate of oxygen supply, i.e. local DO2. Inadequate blood volume leads to impairment of the regulation of blood flow, particularly in the individual tissues with least capable auto-regulatory capability. As demonstrated by many studies, inadequate blood flow first occurs in the gut, brain and kidney. The inadequate blood volume which occurs with induction of anaesthesia is not due to blood volume loss, but probably results from redistribution due to veno-dilation. The increase in venous capacity renders the existing blood volume inadequate to maintain venous return and pre-load. Blood volume shifted to the veins will, necessarily, also reduce the arterial volume. As a result stroke volume and cardiac output fall below normal with little or no change in peripheral resistance. The resulting pre-load dependency is often successfully treated with colloid infusion and, in some studies, 'inotropic' agents, particularly in the immediate post-operative phase. Treatment during the earliest stage of anaesthesia can avoid the build up of oxygen debt and may be supplemented by drugs which maintain or restore venous tone, such as phenylephrine; an alternative to volume expansion. Interpretation of circulatory patho-physiology during anaesthesia confirms the need to sustain appropriate oxygen delivery. It also supports reduction or even elimination of supplementary crystalloid maintenance infusion, supposedly to replace the "mythical" third space loss. As a rational evidence base for future research it should allow for further improvements in anaesthetic management.
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Affiliation(s)
- Christopher B Wolff
- Clinical Research Centre, William Harvey Research Institute, Barts and The London Hospital Medical and Dental School, Queen Mary College, Charterhouse Square, London EC1M 6BQ, UK.
| | - David W Green
- Anaesthetics Department, King's College Hospital NHS Foundation Trust and King's College School of Medicine and Dentistry, London SE5 9RS, UK
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Picano E, Bruno RM, Ferrari GF, Bonuccelli U. Cognitive impairment and cardiovascular disease: so near, so far. Int J Cardiol 2014; 175:21-9. [PMID: 24856805 DOI: 10.1016/j.ijcard.2014.05.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 04/30/2014] [Accepted: 05/05/2014] [Indexed: 01/08/2023]
Abstract
In the spectrum of cognitive impairment, ranging from "pure" vascular dementia to Alzheimer's disease (AD), clinical interest has recently expanded from the brain to also include the vessels, shifting the pathophysiological focus from the leaves of synaptic dysfunction to the sap of cerebral microcirculation and the roots of cardiovascular function. From a diagnostic viewpoint, a thorough clinical evaluation of individuals presenting cognitive impairment might systematically include the assessment of the major cardiovascular rings of the chain linking regional perfusion to brain function: 1) lung (with assessment of asthma, chronic obstructive pulmonary disease, obstructive sleep apnea syndrome); 2) heart function (with clinical examination and echocardiography) and cardiovascular risk factors; 3) orthostatic hypotension (with medical history and measurement of heart rate and blood pressure in supine and upright positions); 4) aorta and large artery stiffness (with assessment of pulse wave velocity); 5) large cerebro-vascular vessel status (with neuroimaging techniques); 6) assessment of microcirculation (with cerebrovascular reactivity testing with transcranial Doppler sonography or MRI perfusion imaging); and 7) assessment of venous cerebral circulation. The apparent difference in approaches to "brain" and "vascular" environmental enrichment with physical, cognitive and sensorial training is conceptually identical to that of a constant gardener caring for an unhealthy tree, watering the leaves ("train the brain") or simply the roots ("mind the vessel"). The therapeutic difference probably consists in the amount and quality of water added to the tree, rather than by where one pours it, with either a top-down (leaves to roots) or bottom-up (roots to leaves) approach.
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Affiliation(s)
| | | | | | - Ubaldo Bonuccelli
- Department of Clinical and Experimental Medicine, Neurology Unit, University of Pisa, Pisa, Italy
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Moderate hyperventilation during intravenous anesthesia increases net cerebral lactate efflux. Anesthesiology 2014; 120:335-42. [PMID: 24008921 DOI: 10.1097/aln.0b013e3182a8eb09] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Hyperventilation is known to decrease cerebral blood flow (CBF) and to impair cerebral metabolism, but the threshold in patients undergoing intravenous anesthesia is unknown. The authors hypothesized that reduced CBF associated with moderate hyperventilation might impair cerebral aerobic metabolism in patients undergoing intravenous anesthesia. METHODS Thirty male patients scheduled for coronary surgery were included in a prospective, controlled crossover trial. Measurements were performed under fentanyl-midazolam anesthesia in a randomized sequence aiming at partial pressures of carbon dioxide of 30 and 50 mmHg. Endpoints were CBF, blood flow velocity in the middle cerebral artery, and cerebral metabolic rates for oxygen, glucose, and lactate. Global CBF was measured using a modified Kety-Schmidt technique with argon as inert gas tracer. CBF velocity of the middle cerebral artery was recorded by transcranial Doppler sonography. Data were presented as mean (SD). Two-sided paired t tests and one-way ANOVA for repeated measures were used for statistical analysis. RESULTS Moderate hyperventilation significantly decreased CBF by 60%, blood flow velocity by 41%, cerebral oxygen delivery by 58%, and partial pressure of oxygen of the jugular venous bulb by 45%. Cerebral metabolic rates for oxygen and glucose remained unchanged; however, net cerebral lactate efflux significantly increased from -0.38 (2.18) to -2.41(2.43) µmol min 100 g. CONCLUSIONS Moderate hyperventilation, when compared with moderate hypoventilation, in patients with cardiovascular disease undergoing intravenous anesthesia increased net cerebral lactate efflux and markedly reduced CBF and partial pressure of oxygen of the jugular venous bulb, suggesting partial impairment of cerebral aerobic metabolism at clinically relevant levels of hypocapnia.
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Green D, Bidd H, Rashid H. Multimodal intraoperative monitoring: an observational case series in high risk patients undergoing major peripheral vascular surgery. Int J Surg 2014; 12:231-6. [PMID: 24412536 DOI: 10.1016/j.ijsu.2013.12.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 12/25/2013] [Indexed: 01/24/2023]
Abstract
Recent guidelines from the National Institute of Health and Care Excellence (NICE) and the UK National Health Service (NHS) have stipulated that intraoperative flow monitoring should be used in high-risk patients undergoing major surgery to improve outcomes and reduce costs. Depth of anaesthesia monitoring is also recommended for patients where excessive anaesthetic depth is poorly tolerated, along with cerebral oximetry in patients with proximal femoral fractures. The aims of this descriptive case series were to evaluate the impact of a multimodal intraoperative strategy and its effect on mortality and amputation rate for patients with critical leg ischaemia. In an observational case series, 120 elderly patients undergoing major infra-inguinal bypass between 2007 and 2012 were included in this retrospective analysis of prospectively collected data. Nominal cardiac output (nCO, LiDCOrapid, LiDCO Ltd, UK), bispectral index to monitor depth of anaesthesia (BIS, Covidien, USA) and cerebral oxygenation, rSO2 (Invos, Covidien, USA) readings were obtained before induction of general anaesthesia and throughout surgery. 30 day, 1-year mortality and amputation rates were analysed. Demographics and physiological parameters including correlation with V-POSSUM, age, gender and other co-morbidities were statistically analysed. Thirty-day mortality rate was 0.8% (n = 1). V-POSSUM scoring indicated a predicted mortality of 9%. Amputation rate was less than 2% at one year. Only 8% of patients (10 of 120) were admitted to a high dependency unit (HDU) postoperatively. 30-day mortality in our case series was lower than predicted by V-POSSUM scoring. Use of multimodal intraoperative monitoring with the specific aim of limiting build-up of oxygen debt should be subjected to a randomised controlled study to assess the reproducibility of these results.
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Affiliation(s)
- David Green
- King's College Hospital NHS Foundation Trust, Denmark Hill, London SE5 9RS, UK.
| | - Heena Bidd
- Guy's and St. Thomas' NHS Foundation Trust, Westminster Bridge Road, London SE1 7EH, UK.
| | - Hisham Rashid
- King's College Hospital NHS Foundation Trust, Denmark Hill, London SE5 9RS, UK.
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Alvarez A, Singh PM, Sinha AC. Tissue oxygenation in morbid obesity – The physiological and clinical perspective. TRENDS IN ANAESTHESIA AND CRITICAL CARE 2013. [DOI: 10.1016/j.tacc.2013.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Cutaneous respirometry by dynamic measurement of mitochondrial oxygen tension for monitoring mitochondrial function in vivo. Mitochondrion 2013; 13:507-14. [DOI: 10.1016/j.mito.2012.10.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 09/19/2012] [Accepted: 10/02/2012] [Indexed: 11/23/2022]
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Bidd H, Tan A, Green D. Using bispectral index and cerebral oximetry to guide hemodynamic therapy in high-risk surgical patients. Perioper Med (Lond) 2013; 2:11. [PMID: 24472198 PMCID: PMC3964341 DOI: 10.1186/2047-0525-2-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 04/26/2013] [Indexed: 12/13/2022] Open
Abstract
High-risk surgery represents 12.5% of cases but contributes 80% of deaths in the elderly population. Reduction in morbidity and mortality by the use of intervention strategies could result in thousands of lives being saved and savings of up to £400m per annum in the UK. This has resulted in the drive towards goal-directed therapy and intraoperative flow optimization of high-risk surgical patients being advocated by authorities such as the National Institute of Health and Care Excellence and the Association of Anaesthetists of Great Britain and Ireland.Conventional intraoperative monitoring gives little insight into the profound physiological changes occurring as a result of anesthesia and surgery. The build-up of an oxygen debt is associated with a poor outcome and strategies have been developed in the postoperative period to improve outcomes by repayment of this debt. New monitoring technologies such as minimally invasive cardiac output, depth of anesthesia and cerebral oximetry can minimize oxygen debt build-up. This has the potential to reduce complications and lessen the need for postoperative optimization in high-dependency areas.Flow monitoring has thus emerged as essential during intraoperative monitoring in high-risk surgery. However, evidence suggests that current optimization strategies of deliberately increasing flow to meet predefined targets may not reduce mortality.Could the addition of depth of anesthesia and cerebral and tissue oximetry monitoring produce a further improvement in outcomes?Retrospective studies indicate a combination of excessive depth of anesthesia hypotension and low anesthesia requirement results in increased mortality and length of hospital stay.Near infrared technology allows assessment and maintenance of cerebral and tissue oxygenation, a strategy, which has been associated with improved outcomes. The suggestion that the brain is an index organ for tissue oxygenation, especially in the elderly, indicates a role for this technology in the intraoperative period to assess the adequacy of oxygen delivery and reduce the build-up of an oxygen debt.The aim of this article is to make the case for depth of anesthesia and cerebral oximetry alongside flow monitoring as a strategy for reducing oxygen debt during high-risk surgery and further improve outcomes in high-risk surgical patients.
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Affiliation(s)
- Heena Bidd
- King’s College Hospital NHS Foundation Trust, Denmark Hill, London, SE5 9RS, UK
| | - Audrey Tan
- King’s College Hospital NHS Foundation Trust, Denmark Hill, London, SE5 9RS, UK
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Oxygen delivery: the principal role of the circulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 789:37-42. [PMID: 23852474 DOI: 10.1007/978-1-4614-7411-1_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Autoregulation of blood flow to most individual organs is well known. The balance of oxygen supply relative to the rate of oxygen consumption ensures normal function. There is less reserve as regards oxygen supply than for any other necessary metabolite or waste product so oxygen supply is flow dependent. Reduced rate of supply compromises tissue oxygenation long before any other substance. The present report reiterates evidence from earlier studies demonstrating that the rate of oxygen delivery (DO2), for most individual tissues, is well sustained at a value bearing a ratio to oxygen consumption (VO2) which is specific for the organ concerned. For the brain DO2 is sustained at approximately three times the rate of oxygen consumption and for exercising skeletal muscle (below the anaerobic threshold), a ratio close to 1.5. The tissue-specific ratios are sustained in the face of alterations in local VO2 and lowered arterial oxygen content (CaO2). Tolerance varies between different organs. Hence, the role of the circulation is predominantly one of ensuring an adequate supply of oxygen. The precise values of the individual tissue DO2:VO2 ratios apply within physiological ranges which require further investigation.
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Wasse LK, Sunderland C, King JA, Batterham RL, Stensel DJ. Influence of rest and exercise at a simulated altitude of 4,000 m on appetite, energy intake, and plasma concentrations of acylated ghrelin and peptide YY. J Appl Physiol (1985) 2012; 112:552-9. [DOI: 10.1152/japplphysiol.00090.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The reason for high altitude anorexia is unclear but could involve alterations in the appetite hormones ghrelin and peptide YY (PYY). This study examined the effect of resting and exercising in hypoxia (12.7% O2; ∼4,000 m) on appetite, energy intake, and plasma concentrations of acylated ghrelin and PYY. Ten healthy males completed four, 7-h trials in an environmental chamber in a random order. The four trials were control-normoxia, control-hypoxia, exercise-normoxia, and exercise-hypoxia. During exercise trials, participants ran for 60 min at 70% of altitude-specific maximal oxygen consumption (V̇o2max) and then rested. Participants rested throughout control trials. A standardized meal was consumed at 2 h and an ad libitum buffet meal at 5.5 h. Area under the curve values for hunger (assessed using visual analog scales) tended to be lower during hypoxic trials than normoxic trials (repeated-measures ANOVA, P = 0.07). Ad libitum energy intake was lower ( P = 0.001) in hypoxia (5,291 ± 2,189 kJ) than normoxia (7,718 ± 2,356 kJ; means ± SD). Mean plasma acylated ghrelin concentrations were lower in hypoxia than normoxia (82 ± 66 vs. 100 ± 69 pg/ml; P = 0.005) while PYY concentrations tended to be higher in normoxia (32 ± 4 vs. 30 ± 3 pmol/l; P = 0.059). Exercise suppressed hunger and acylated ghrelin and increased PYY but did not influence ad libitum energy intake. These findings confirm that hypoxia suppresses hunger and food intake. Further research is required to determine if decreased concentrations of acylated ghrelin orchestrate this suppression.
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Affiliation(s)
- Lucy K. Wasse
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough
| | - Caroline Sunderland
- School of Science and Technology, Nottingham Trent University, Nottingham; and
| | - James A. King
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough
| | | | - David J. Stensel
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough
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42
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Oscillations in cardiac output in hypoxia with periodic breathing and constant end-tidal PCO₂ at high altitude (5,000 m). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 737:197-206. [PMID: 22259102 DOI: 10.1007/978-1-4614-1566-4_29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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43
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Regulation of oxygen delivery by the reaction of nitrite with RBCs under hypoxic conditions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 737:183-9. [PMID: 22259100 DOI: 10.1007/978-1-4614-1566-4_27] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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44
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Shander A, Javidroozi M, Ozawa S, Hare G. What is really dangerous: anaemia or transfusion? Br J Anaesth 2011; 107 Suppl 1:i41-59. [DOI: 10.1093/bja/aer350] [Citation(s) in RCA: 350] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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45
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De Blasi RA, Tonelli E, Arcioni R, Mercieri M, Cigognetti L, Romano R, Pinto G. In vivo effects on human skeletal muscle oxygen delivery and metabolism of cardiopulmonary bypass and perioperative hemodilution. Intensive Care Med 2011; 38:413-21. [DOI: 10.1007/s00134-011-2404-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 10/14/2011] [Indexed: 11/28/2022]
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46
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The Relationship of Acute Mountain Sickness to Arterial Oxygen Saturation at Altitudes of 3,324 to 5,176 m. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011. [DOI: 10.1007/978-1-4614-1566-4_30] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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47
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Bell M, Thake CD, Wolff CB. Effect of inspiration of 12% O₂ (balance N₂) on cardiac output, respiration, oxygen saturation, and oxygen delivery. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 701:327-32. [PMID: 21445805 DOI: 10.1007/978-1-4419-7756-4_44] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Low arterial oxygen saturation (SaO(2)) will result in a reduced rate of arterial oxygen delivery to the tissues (DO(2)), unless there is a compensatory increase in cardiac output (CO) or haemoglobin concentration (Hb). An adequate DO(2) can therefore be maintained by increasing ventilation, CO, or both. Sustaining a tissue specific oxygen extraction is thought to play an important part in overall compensation. The present study has examined responses to acute hypoxic exposure in 8 volunteers (breathing 12% oxygen, balance nitrogen) and describes changes in CO, ventilation and the SaO(2). Aims included: examination of the extent of intersubject variations and seeing whether DO(2) was maintained. SaO(2), PCO(2), respiration (via stethograph) and Finapress (non-invasive) arterial blood pressure (BP) were recorded, firstly on air and then on 12% oxygen. CO was derived, off-line, from the BP record. CO was increased in 5 subjects (22%-45%) but was virtually unchanged in 3, and yet comparison for all 8 subjects showed that DO(2) on 12% oxygen was not significantly different from DO(2) on air (mean on air 1017 ml. min(-1); hypoxia 1080 ml. min(-1), p = 0.27). SaO(2) on 12% oxygen ranged between 85% and 93%. In conclusion, exposure to the same hypoxic gas mixture resulted in differing individual ventilatory and CO responses. However, DO(2) was well maintained.
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Affiliation(s)
- M Bell
- St. Catherine's Hospital, Doncaster, UK
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48
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Pestel GJ, Fukui K, Kimberger O, Hager H, Kurz A, Hiltebrand LB. Hemodynamic Parameters Change Earlier Than Tissue Oxygen Tension in Hemorrhage. J Surg Res 2010; 160:288-93. [DOI: 10.1016/j.jss.2008.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 10/30/2008] [Accepted: 11/03/2008] [Indexed: 11/17/2022]
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49
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Noninvasive quantitative measurement of myocardial and whole-body oxygen consumption using MRI: initial results. Magn Reson Imaging 2009; 27:147-54. [DOI: 10.1016/j.mri.2008.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 05/17/2008] [Accepted: 06/17/2008] [Indexed: 11/19/2022]
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50
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