Study of Methemoglobin as a Biomarker of Tissue Hypoxia During Acute Hemodilution in Heart Surgery Patients
16. april 2018 opdateret af: Unity Health Toronto
A Prospective Analysis of Methemoglobin as a Biomarker of Tissue Hypoxia During Acute Hemodilutional Anemia in Patients Undergoing Heart Surgery
Acute and chronic anemia continue to be associated with increased mortality in a number of clinical settings, including cardiac and non-cardiac surgery. However, "We have no clinical measures that let us know of impending insufficient oxygenation as anemia progresses" (R.B. Weiskopf). The current proposal is based on experimental and clinical data which suggest that plasma methemoglobin (MetHb) may be a sensitive biomarker of tissue hypoxia and "anemic stress" in surgical patients.
Hypothesis: Increased methemoglobin is a biomarker of tissue hypoxia during acute anemia.
Primary Objective: To demonstrate a direct relationship between decreased Hb and increased MetHb in patients undergoing acute hemodilution on cardiopulmonary bypass (CPB).
Studieoversigt
Status
Afsluttet
Intervention / Behandling
Detaljeret beskrivelse
Acute and chronic anemia continue to be associated with increased mortality in a number of clinical settings, including cardiac and non-cardiac surgery.
1-6 However, as recently stated by one of the pioneers of anemia research; Dr. R.B. Weiskopf: "We have no clinical measures that let us know of impending insufficient oxygenation as anemia progresses".7 Toward achieving this goal, we have developed experimental models to define the adaptive mechanisms which maintain oxygen homeostasis during acute anemia.
Our research has identified that increased nitric oxide (NO) production by nitric oxide syntheses (NOSs) may be an important survival mechanism in acute anemia.3;8;9
Experimental data suggests that nNOS may promote survival by maintaining oxygen (O2) homeostasis during acute anemia.10
Resultant increases in nitric oxide (NO) contributes to adaptive cell signaling mechanisms and also increase oxidation of hemoglobin (Hb) to methemoglobin (MetHb).3
In addition, oxygen extraction results in increased levels of deoxyhemoglobin which has been proposed to act as a nitrite (NO2-) reductase to generate additional bioactive NO, thereby promoting vasodilation in hypoxic vascular beds.11-15
Thus, by more than one mechanism, increased MetHb may be indicative of hemoglobin desaturation, tissue hypoxia and activation of adaptive tissue responses to anemia.
These responses may identify the threshold for local tissue hypoxia or "anemic stress".
In attempt to determine if such mechanisms are active in humans we performed a retrospective study in patients undergoing cardiopulmonary bypass (CPB) during heart surgery to determine if plasma MetHb increased as Hb decreased during CPB.
We observed an inverse relationship between Hb and MetHb that was independent of red blood cell transfusion and exogenous nitrate use
Undersøgelsestype
Observationel
Tilmelding (Faktiske)
68
Kontakter og lokationer
Dette afsnit indeholder kontaktoplysninger for dem, der udfører undersøgelsen, og oplysninger om, hvor denne undersøgelse udføres.
Studiesteder
-
-
Ontario
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Toronto, Ontario, Canada, M5B 1W8
- St. Michael's Hospital
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Deltagelseskriterier
Forskere leder efter personer, der passer til en bestemt beskrivelse, kaldet berettigelseskriterier. Nogle eksempler på disse kriterier er en persons generelle helbredstilstand eller tidligere behandlinger.
Berettigelseskriterier
Aldre berettiget til at studere
18 år til 65 år (Voksen, Ældre voksen)
Tager imod sunde frivillige
Ingen
Køn, der er berettiget til at studere
Alle
Prøveudtagningsmetode
Ikke-sandsynlighedsprøve
Studiebefolkning
heart surgery with cardiopulmonary bypass
Beskrivelse
Inclusion Criteria:
- patients undergoing heart surgery using cardiopulmonary bypass at St. Michael's Hospital who have a pre-operative Hb value greater than 90 g/L, no evidence of hypoxemia (SaO2 > 90%) and no history of congenital methemoglobinemia.
Exclusion Criteria:
- severe hypoxemia, acute or chronic renal failure requiring dialysis, emergency surgery or the lack of a PA catheter (current standard of care at St. Michael's Hospital is to insert a PA catheter in > 90% of patients).
Studieplan
Dette afsnit indeholder detaljer om studieplanen, herunder hvordan undersøgelsen er designet, og hvad undersøgelsen måler.
Hvordan er undersøgelsen tilrettelagt?
Design detaljer
Kohorter og interventioner
Gruppe / kohorte |
Intervention / Behandling |
|---|---|
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Heart surgery during CPB
All patients undergoing heart surgery using cardiopulmonary bypass who have a pre-operative Hb value greater than 90 g/L, no evidence of hypoxemia (SaO2 > 90%) and no history of congenital methemoglobinemia.
Exclusion criteria will include severe hypoxemia, acute or chronic renal failure requiring dialysis, emergency surgery or the lack of a PA catheter.
Non invasive brain oximetry will be used to assess the brain oxygen tension during surgical procedure.
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Non invasive brain oximeter will be applied on the patient's forehead to monitor the brain oxygen saturation throughout the surgery.
Andre navne:
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Hvad måler undersøgelsen?
Primære resultatmål
Resultatmål |
Foranstaltningsbeskrivelse |
Tidsramme |
|---|---|---|
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Arterial methemoglobin levels
Tidsramme: 18 months
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To determine if there is an association between increased methemoglobin and tissue hypoxia following heart surgery
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18 months
|
Sekundære resultatmål
Resultatmål |
Foranstaltningsbeskrivelse |
Tidsramme |
|---|---|---|
|
Cerebral tissue oxygen saturation
Tidsramme: 18 months
|
18 months
|
|
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Plasma erythropoietin levels
Tidsramme: 18 months
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18 months
|
|
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Plasma nitrate/nitrite levels
Tidsramme: 18 months
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18 months
|
|
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Plasma hepcidin levels
Tidsramme: 18 months
|
Relationship between plasma hepcidin levels and hemoglobin levels
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18 months
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Andre resultatmål
Resultatmål |
Tidsramme |
|---|---|
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Adverse outcomes including mortality, myocardial infarction, low output syndrome, stroke and renal dysfunction
Tidsramme: 18 months
|
18 months
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Samarbejdspartnere og efterforskere
Det er her, du vil finde personer og organisationer, der er involveret i denne undersøgelse.
Sponsor
Efterforskere
- Ledende efterforsker: Gregory Hare, MD, PhD, Unity Health Toronto
Publikationer og nyttige links
Den person, der er ansvarlig for at indtaste oplysninger om undersøgelsen, leverer frivilligt disse publikationer. Disse kan handle om alt relateret til undersøgelsen.
Datoer for undersøgelser
Disse datoer sporer fremskridtene for indsendelser af undersøgelsesrekord og resumeresultater til ClinicalTrials.gov. Studieregistreringer og rapporterede resultater gennemgås af National Library of Medicine (NLM) for at sikre, at de opfylder specifikke kvalitetskontrolstandarder, før de offentliggøres på den offentlige hjemmeside.
Studer store datoer
Studiestart
1. januar 2013
Primær færdiggørelse (Faktiske)
1. august 2016
Studieafslutning (Faktiske)
1. august 2016
Datoer for studieregistrering
Først indsendt
11. marts 2013
Først indsendt, der opfyldte QC-kriterier
19. juni 2013
Først opslået (Skøn)
21. juni 2013
Opdateringer af undersøgelsesjournaler
Sidste opdatering sendt (Faktiske)
17. april 2018
Sidste opdatering indsendt, der opfyldte kvalitetskontrolkriterier
16. april 2018
Sidst verificeret
1. april 2018
Mere information
Begreber relateret til denne undersøgelse
Nøgleord
Yderligere relevante MeSH-vilkår
Andre undersøgelses-id-numre
- REB# 12-015
Disse oplysninger blev hentet direkte fra webstedet clinicaltrials.gov uden ændringer. Hvis du har nogen anmodninger om at ændre, fjerne eller opdatere dine undersøgelsesoplysninger, bedes du kontakte register@clinicaltrials.gov. Så snart en ændring er implementeret på clinicaltrials.gov, vil denne også blive opdateret automatisk på vores hjemmeside .