Mild hypothermia alters the oxygen consumption/delivery relationship by decreasing the slope of the supply-dependent line

Oda, Jun; Kuwagata, Yasuyuki; Nakamori, Yasushi; Noborio, Mitsuhiro; Hayakata, Toshiaki; Fujimi, Satoshi; Sugimoto, Hisashi

doi:10.1097/00003246-200207000-00023

Cited by 13 publications

(6 citation statements)

References 20 publications

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“…Also, decrease in temperature markedly increases the affinity of hemoglobin for oxygen (Dexter et al, 1997). As temperature is reduced the corresponding increase in hemoglobin/oxygen affinity causes a progressive impairment of oxygen transfer from hemoglobin, with subsequent decreases in transfer to cerebral interstitium and cells (Oda et al, 2002) functional brain activation, a disproportional increase in blood flow compared to oxygen consumption (Fox and Raichle, 1986) can lead to changes in regional brain temperature that depend on the arterial/brain temperature differential (Yablonskiy et al, 2000). Third, numerous recent investigations initiated by Busto et al (1987) indicate that mild hypothermia (2-3 1C) can significantly influence the survival of cerebral tissue during ischemia.…”

Section: Introductionmentioning

confidence: 99%

On the role of anesthesia on the body/brain temperature differential in rats

Zhu

Nehra

Ackerman

et al. 2004

Journal of Thermal Biology

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Section: Introductionmentioning

confidence: 99%

On the role of anesthesia on the body/brain temperature differential in rats

Zhu

Nehra

Ackerman

et al. 2004

Journal of Thermal Biology

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“…Certainly, in mildly hypothermic mammals (T b ϳ 30°C), there is evidence for a reduction in (Ca O 2 Ϫ Cv O 2 ), but only under situations where V O 2 has become supply dependent (Ref. 32, and references within). Whether or not the leftward shift of the hemoglobin oxygen equilibrium curve associated with the decline in T b is causal to the reduction in (Ca O 2 Ϫ Cv O 2 ) remains contentious, though, as yet, this has only been studied by artificial manipulation of hemoglobin-oxygen affinity (19,38).…”

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confidence: 99%

Factorial scopes of cardio-metabolic variables remain constant with changes in body temperature in the varanid lizard,Varanus rosenbergi

Wang¹,

Butler²,

Frappell³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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The majority of information concerning the cardio-metabolic performance of varanids during exercise is limited to a few species at their preferred body temperature (T(b)) even though, being ectotherms, varanids naturally experience rather large changes in T(b). Although it is well established that absolute aerobic scope declines with decreasing T(b), it is not known whether changes in cardiac output (V(b)) and/or tissue oxygen extraction, (Ca(O2) - Cv(O2)), are in proportion to the rate of oxygen consumption (Vo(2)). To test this, we studied six Rosenberg's goannas (Varanus rosenbergi) while at rest and while maximally exercising on a treadmill both at 25 and 36 degrees C. During maximum exercise both at 25 and 36 degrees C, mass-specific rate of oxygen consumption (Vo(2kg)) increased with an absolute scope of 8.5 ml min(-1) kg(-1) and 15.7 ml min(-1) kg(-1), respectively. Interestingly, the factorial aerobic scope was temperature-independent and remained at 7.0 which, at each T(b), was primarily the result of an increase in V(bkg), governed by approximate twofold increases both in heart rate (f(H)) and cardiac stroke volume (V(Skg)). Both at 25 degrees C and 36 degrees C, the increase in V(bkg) alone was not sufficient to provide all of the additional oxygen required to attain maximal Vo(2kg), as indicated by a decrease in the blood convection requirement V(bkg)/Vo(2kg); hence, there was a compensatory twofold increase in (Ca(O2) - Cv(O2)). Although associated with an increase in hemoglobin-oxygen affinity, a decrease in T(b) did not impair unloading of oxygen at the tissues and act to reduce (Ca(O2) - Cv(O2)); both Ca(O2)) and Cv(O2)) were maintained across T(b). The change in Vo(2kg) with T(b), therefore, is solely reliant on the thermal dependence of V(bkg). Maintaining a high factorial aerobic scope across a range of T(b) confers an advantage in that cooler animals can achieve higher absolute aerobic scopes and presumably improved aerobic performance than would otherwise be achievable.

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“…Data obtained from intact rabbits during our previous studies showed that mean DO 2 crit values and mean oxygen extraction ratios range from 11.5 to 13.3 mL/min/kg and from 72 to 83%, respectively (22–24). Oxygen uptake was higher in both the NRC and RBC groups as indicated by a lower DO 2 crit value and a higher oxygen extraction ratio at the critical point compared with our historical data.…”

Section: Discussionmentioning

confidence: 42%

Effects of Exchange Transfusion With Liposome‐Encapsulated Hemoglobin on VO₂/DO₂

Ikegawa¹,

Kuwagata²,

Hayakawa³

et al. 2011

Artificial Organs

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We clarified the effect of exchange transfusion with liposome-encapsulated hemoglobin (neo red cells, NRCs) with low O₂ affinity (P₅₀O₂ = 50 mm Hg) on O₂ metabolism. Rabbits were randomly assigned to receive serial exchange transfusions with NRC (NRC group, n = 5), shed blood diluted 1:1 with saline (red blood cell (RBC) group, n = 5), or saline alone (plasma group, n = 4) under hemodynamic monitoring. Cardiac tamponade was then induced and successively reversed to determine relationships between O₂ consumption (VO₂) and O₂ delivery (DO₂) using the dual-line method. Mean values of Hb concentration after exchange transfusion were 5.7 (NRC), 6.0 (RBC), and 1.5 (plasma) g/dL. The plasma group could not even survive the initial exchange hemodilution due to a critical decrease in DO₂. The NRC, but not the RBC group, developed progressive metabolic acidosis and lactatemia, as well as increases in PaCO₂ and decreases in tissue PO₂ in skeletal muscle after exchange transfusion. Nonetheless, systemic O₂ uptake indices obtained from an analysis of the VO₂/DO₂ relationship in the NRC and RBC groups were comparable. These findings suggested that systemic O₂ uptake was maintained in rabbits after exchange transfusion with NRC, although progressive tissue hypoxia with systemic acidosis is indicative of inadequate peripheral circulation and insufficient aerobic metabolism during extended hemodilution in which 86% of the circulating blood is replaced.

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Mild hypothermia alters the oxygen consumption/delivery relationship by decreasing the slope of the supply-dependent line

Abstract: The potential for tissue hypoxia is likely to be increased during hypothermia when the circulation becomes unstable and oxygen delivery decreases.

Cited by 13 publications

References 20 publications

On the role of anesthesia on the body/brain temperature differential in rats

On the role of anesthesia on the body/brain temperature differential in rats

Factorial scopes of cardio-metabolic variables remain constant with changes in body temperature in the varanid lizard,Varanus rosenbergi

Effects of Exchange Transfusion With Liposome‐Encapsulated Hemoglobin on VO₂/DO₂

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Mild hypothermia alters the oxygen consumption/delivery relationship by decreasing the slope of the supply-dependent line

Abstract: The potential for tissue hypoxia is likely to be increased during hypothermia when the circulation becomes unstable and oxygen delivery decreases.

Cited by 13 publications

References 20 publications

On the role of anesthesia on the body/brain temperature differential in rats

On the role of anesthesia on the body/brain temperature differential in rats

Factorial scopes of cardio-metabolic variables remain constant with changes in body temperature in the varanid lizard,Varanus rosenbergi

Effects of Exchange Transfusion With Liposome‐Encapsulated Hemoglobin on VO2/DO2

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Effects of Exchange Transfusion With Liposome‐Encapsulated Hemoglobin on VO₂/DO₂