Hypothermia and advanced neuromonitoring

Helbok, Raimund; Schiefecker, Alois Josef; Fischer, Marlene; Dietmann, Anelia; Schmutzhard, Erich

doi:10.1186/cc11285

Cited by 2 publications

(4 citation statements)

References 49 publications

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“…While a decreased rate of glucose metabolism can be caused by decreased glucose availability, lamellar glucose concentration was similar between CDH and AMB limbs, which indicates that CDH decreased the rate of glucose metabolism by decreasing lamellar glucose uptake and utilisation. This is consistent with hypothermia studies of the central nervous system that have found hypothermia to reduce the cerebral metabolic rate of glucose ATP breakdown and synthesis and slow down lactate formation . Importantly, it is thought that these effects help maintain cerebral ATP supply, thereby preventing secondary cellular energy failure associated with trauma, ischaemia and sepsis .…”

Section: Discussionsupporting

confidence: 84%

“…Urea clearance decreased in CON CDH and EHC CDH relative to CON AMB (P = .002) and EHC AMB (P < .001) respectively but did not change significantly in OF CDH relative to OF AMB (P = .4). Urea clearance was lowest at 18 hours in CON CDH limbs (28% [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]) and at 36 hours in EHC CDH (24 % [23-26]) and OF CDH (33% [29-59]) (Figure 1B, D, F).…”

Section: Urea Clearancementioning

confidence: 99%

“…This is consistent with hypothermia studies of the central nervous system that have found hypothermia to reduce the cerebral metabolic rate of glucose ATP breakdown and synthesis and slow down lactate formation. 9,26 Importantly, it is thought that these effects help maintain cerebral ATP supply, thereby preventing secondary cellular energy failure associated with trauma, ischaemia and sepsis. 9,16,27 In the current study there was some evidence of nonischaemic oxidative energy failure in OF AMB and EHC AMB limbs, marked by an increase in L:P. 27 This was not noted in a previous OF model study over 24 hours; 20 however, the effect occurred mostly in the final 12 hours of the current 36 hours study in OF horses.…”

Section: F I G U R E 1 Median (Iqr) Lamellar Microdialysate Glucose Concentration and Urea Clearance In Ambient (Amb) And Continuously Comentioning

confidence: 99%

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The effect of continuous digital hypothermia on lamellar energy metabolism and perfusion during laminitis development in two experimental models

Stokes

Bertin

Stefanovski

et al. 2020

Equine Veterinary Journal

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Background Continuous digital hypothermia (CDH) prevents lamellar failure in the euglycaemic hyperinsulinaemic clamp (EHC) and oligofructose (OF) laminitis models, but the mechanisms remain unclear. Objectives To evaluate the effects of CDH on lamellar energy metabolism and perfusion in healthy horses and during EHC and OF laminitis models. Study design In vivo experiment. Methods Archived samples were used from Standardbred geldings that received no treatment (CON) (n = 8) or underwent EHC (n = 8) or OF (n = 6) laminitis models. Both forelimbs were instrumented with a lamellar microdialysis system, and one forelimb was cooled (CDH) with the other maintained at ambient temperature (AMB). Microdialysate was collected every 6 hours and analysed for glucose, lactate and pyruvate concentrations and lactate to pyruvate ratio (L:P). Microdialysis urea clearance was used to estimate lamellar tissue perfusion. Data were analysed using a mixed‐effects linear regression model. Results Glucose did not change in CDH limbs relative to AMB in CON (P = .3), EHC (P = .3) or OF (P = .6) groups. There was a decrease in lactate (P < .001) and pyruvate (P < .01) in CDH limbs relative to AMB in all groups. L:P decreased in CON CDH relative to CON AMB (P < .001) but was not different in EHC (P = .6) and OF (P = .07) groups. Urea clearance decreased in CDH limbs relative to AMB in CON (P = .002) and EHC (P < .001), but not in OF (P = .4). Main limitations The EHC model may not mimic natural endocrinopathic laminitis. Conclusions CDH caused a marked decrease in lamellar glucose metabolism (CON, EHC and OF) and perfusion (CON and EHC) without affecting lamellar glucose concentration. Although cellular energy failure is not a primary pathophysiological event in EHC and OF laminitis models, CDH may act by limiting energy supply to pathologic cellular processes whilst preserving those critical to lamellar homoeostasis.

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Section: Discussionsupporting

confidence: 84%

Section: Urea Clearancementioning

confidence: 99%

Section: F I G U R E 1 Median (Iqr) Lamellar Microdialysate Glucose Concentration and Urea Clearance In Ambient (Amb) And Continuously Comentioning

confidence: 99%

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The effect of continuous digital hypothermia on lamellar energy metabolism and perfusion during laminitis development in two experimental models

Stokes

Bertin

Stefanovski

et al. 2020

Equine Veterinary Journal

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“…2. Hypothermia can cause a leftward shift in oxygen distribution curve [5]. This enhances the affinity of oxygen to hemoglobin causing reduced oxygen release and reduced availability to brain cells [5].…”

Section: Discussionmentioning

confidence: 99%

Linear Decrease in Brain Tissue Oxygenation (PbtO2) with Decreasing Body Temperature during Induce Hypothermia

Katyal¹,

Cr²

2018

J Neurol Neurobiol

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Background: Induced mild hypothermia (MIH) is generally an effective intervention for reducing intracranial pressure (ICP) in patients with severe traumatic brain injury (TBI). Unfortunately, MIH also influences brain tissue oxygenation (PbtO2). The significance of the PbtO2 change is unknown. We report a patient with severe traumatic brain injury (TBI) with refractory intracranial hypertension requiring MIH which resulted in a decrease in his PbtO2 values. Case report:The patient presented in a coma following an altercation. He was found to have a large left subdural hemorrhage with significant mass effect requiring craniectomy. He subsequently developed refractory intracranial hypertension requiring medically induced coma and MIH. As temperature decreased, his PbtO2 values decreased from 23-35 mmHg to 6-10 mmHg. There was a significant reduction in PbtO2 values as temperature decreased (p<0.001). ICP did not change with a decrease in temperature and remained elevated (p=0.78). Conclusion:PbtO2 significantly decreased linearly with the decrease in body temperature. Future studies should evaluate the clinical significance of the reduction in PbtO2 in patients with severe TBI and refractory intracranial hypertension requiring MIH. Recognizing expected changes in PbtO2 monitoring with MIH is important for managing neurocritically ill patients.

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Hypothermia and advanced neuromonitoring

Cited by 2 publications

References 49 publications

The effect of continuous digital hypothermia on lamellar energy metabolism and perfusion during laminitis development in two experimental models

The effect of continuous digital hypothermia on lamellar energy metabolism and perfusion during laminitis development in two experimental models

Linear Decrease in Brain Tissue Oxygenation (PbtO2) with Decreasing Body Temperature during Induce Hypothermia

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