Influence of systemic hypothermia on the myocardial oxygen tension during extracorporeal circulation: Comparative study in German Landrace pigs

Matschke, Klaus; Knaut, Michael; Kanig, R.; Mrowietz, C.; Hiebl, Bernhard; Jung, F.

doi:10.3233/ch-2012-1589

Cited by 6 publications

(1 citation statement)

References 31 publications

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“…Determination of whole blood viscosity may be helpful for regulating perfusion in macro-and microcirculation especially during bypass surgery. When the patient's body is cooled from 37 to 22°C with the heart-lung machine, microcirculation is crucially influenced by the rise in blood viscosity, the change in whole blood viscosity due to the inflammatory reactions, and the reduction of temperature (Matschke et al 2012;Holsworth et al 2013). With the new LS300, one is able to determine the viscosity of whole blood according to Casson by cryoregulation, by creating a flow curve, calculating yield shear stress, and obtaining a viscosity curve derived from it.…”

Section: Discussionmentioning

confidence: 99%

Determination of whole blood and plasma viscosity by means of flow curve analysis

Ruef¹,

Gehm²,

Gehm³

et al. 2014

gpb

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The LS300 viscometer permits automated measurements of viscosity at several shear rates of non-Newtonian fluids. We determined whole blood and plasma viscosity, aggregation, red blood cell deformability, and hematocrit of 66 healthy adults. The effects of the anticoagulants EDTA, heparin and citrate, and of centrifugation on blood viscosity (n=12) and red blood cell geometry (n=5) were investigated. With regard to the whole blood viscosity of adults, the best agreement was obtained by Casson's calculation compared to the methods of Ostwald, Bingham and Newton. The approximated flow curve of plasma showed only marginal differences between the method of Newton and Ostwald, whereas the latter gave the best quality of approximation. Centrifugation and the anticoagulants had a significant impact on whole blood viscosity and yield shear stress, whereas erythrocyte geometry remained unaffected. By linear regression of hematocrit with viscosity and yield shear stress, its impact on blood viscosity could be calculated in a hematocrit range of 0.32-0.50. Determination of whole blood viscosity should be performed in a standardized manner at several shear rates and without centrifugation of the blood samples.

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Section: Discussionmentioning

confidence: 99%

Determination of whole blood and plasma viscosity by means of flow curve analysis

Ruef¹,

Gehm²,

Gehm³

et al. 2014

gpb

View full text Add to dashboard Cite

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Growth‐related micromorphological characteristics of the porcine common carotid artery

Nies

Proft

Nehring

et al. 2019

Anat Histol Embryol

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The purpose of this study was to gain knowledge about the micromorphology of the porcine common carotid artery (CCA) during the period of growth over the bodyweight range of 10–40 kg. CCA samples from German landrace pigs (DL) aged either 2 or 3 months (DL‐2 and DL‐3) were compared with samples from Göttingen minipigs (GM) aged either 18 or 40 months (GM‐18 and GM‐40) using transmitted light (phase‐contrast mode) and transmission electron microscopy. The GM‐18, GM‐40 and the DL‐3 groups had typical muscular artery histological characteristics. Contrasting to this, the 2‐month‐old DL pigs had a transitional artery type being characterized by a significantly higher proportion of elastic fibres and a significantly lower number of smooth muscle cells than did the 1 month older DL‐3. During the period of maturation, the tunica media of the CCA in GM animals thickened by 1.3× and in DL animals by 2.5× resulting in an overall increased vessel wall thickness. The cumulated thickness of the tunica interna (endothelium, stratum subendotheliale and internal elastic lamina) and the tunica media (including the external elastic lamina) of DL‐3 and GM‐40 pigs were similar to each other and comparable to that of humans. With an increasing vessel wall thickness, the luminal diameter decreased in GM by 19% and in DL by 11%. Additionally, in the older age groups, GM‐40 and DL‐3, the internal elastic lamina principally was continuous, but there were also interrupted large segments of elastic lamina separated by gaps. In addition, the principal internal elastic lamina was duplicated in several places.

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Moderate Hypothermia Modifies Coronary Hemodynamics and Endothelium‐Dependent Vasodilation in a Porcine Model of Temperature Management

Bobi

Solanes

Dantas

et al. 2020

JAHA

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Background Hypothermia has been associated with therapeutic benefits including reduced mortality and better neurologic outcomes in survivors of cardiac arrest. However, undesirable side effects have been reported in patients undergoing coronary interventions. Using a large animal model of temperature management, we aimed to describe how temperature interferes with the coronary vasculature. Methods and Results Coronary hemodynamics and endothelial function were studied in 12 pigs at various core temperatures. Left circumflex coronary artery was challenged with intracoronary nitroglycerin, bradykinin, and adenosine at normothermia (38°C) and mild hypothermia (34°C), followed by either rewarming (38°C; n=6) or moderate hypothermia (Mo HT ; 32°C, n=6). Invasive coronary hemodynamics by Doppler wire revealed a slower coronary blood velocity at 32°C in the Mo HT protocol (normothermia 20.2±11.2 cm/s versus mild hypothermia 18.7±4.3 cm/s versus Mo HT 11.3±5.3 cm/s, P =0.007). Mo HT time point was also associated with high values of hyperemic microvascular resistance (>3 mm Hg/cm per second) (normothermia 2.0±0.6 mm Hg/cm per second versus mild hypothermia 2.0±0.8 mm Hg/cm per second versus Mo HT 3.4±1.6 mm Hg/cm per second, P =0.273). Assessment of coronary vasodilation by quantitative coronary analysis showed increased endothelium‐dependent (bradykinin) vasodilation at 32°C when compared with normothermia (normothermia 6.96% change versus mild hypothermia 9.01% change versus Mo HT 25.42% change, P =0.044). Results from coronary reactivity in vitro were in agreement with angiography data and established that endothelium‐dependent relaxation in Mo HT completely relies on NO production. Conclusions In this porcine model of temperature management, 34°C hypothermia and rewarming (38°C) did not affect coronary hemodynamics or endothelial function. However, 32°C hypothermia altered coronary vasculature physiology by slowing coronary blood flow, increasing microvascular resistance, and exacerbating endothelium‐dependent vasodilatory response.

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Influence of systemic hypothermia on the myocardial oxygen tension during extracorporeal circulation: Comparative study in German Landrace pigs

Cited by 6 publications

References 31 publications

Determination of whole blood and plasma viscosity by means of flow curve analysis

Determination of whole blood and plasma viscosity by means of flow curve analysis

Growth‐related micromorphological characteristics of the porcine common carotid artery

Moderate Hypothermia Modifies Coronary Hemodynamics and Endothelium‐Dependent Vasodilation in a Porcine Model of Temperature Management

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