Local endovascular infusion and hypothermia in stroke therapy: A systematic review

Hemolysis performance analysis and a novel estimation model of roller pump system

OBJECTIVE

Hemolysis performance is a crucial criterion for roller pumps utilized in life supporting system. In this study, the factor of hemolysis for roller pumps was selected as the target, and an estimation formulation was built to evaluate its hemolysis.

METHODS

Several models were proposed and then simulated with the assistant of Computational fluid dynamics (CFD) framework. The hemolysis performance was calculated using the power law model based on CFD and the estimation model in accordance with geometry parameters proposed in this study. The results of the in vitro experiments were compared with the simulation results. Power law model with the lowest error was utilized in following analysis.

RESULTS

As indicated by the simulation result, the rotary speed most significantly affected the hemolysis performance of roller blood pumps, followed by roller number and diameter of tube. The index of hemolysis (IH) for roller blood pumps at a rotary speed of 20-100 rpm ranged from 8.73E-7 to 8.07E-5. The relative error of the estimation model (4.93%) was lower than of the power law model (6.78%).

CONCLUSION

The IH led by pumps shows a significant, nonlinear relationship with the rotary speed. The design of multiple rollers design is harmful for hemolysis performance and larger diameter of tube exhibits decreased hemolysis at constant flow rate. An estimation formula was proposed with lower relative error for roller pump with the same shell set, which exhibited reduced computation and elevated convenience. And it can be utilized in hemolysis estimation of roller pumps potentially.

Therapeutic hypothermia for stroke: Unique challenges at the bedside

Therapeutic hypothermia has shown promise as a means to improving neurological outcomes at several neurological conditions. At the clinical level, it has been shown to improve outcomes in comatose survivors of cardiac arrest and in neonatal hypoxic ischemic encephalopathy, but has yet to be convincingly demonstrated in stroke. While numerous preclinical studies have shown benefit in stroke models, translating this to the clinical level has proven challenging. Major obstacles include cooling patients with typical stroke who are awake and breathing spontaneously but often have significant comorbidities. Solutions around these problems include selective brain cooling and cooling to lesser depths or avoiding hyperthermia. This review will cover the mechanisms of protection by therapeutic hypothermia, as well as recent progress made in selective brain cooling and the neuroprotective effects of only slightly lowering brain temperature. Therapeutic hypothermia for stroke has been shown to be feasible, but has yet to be definitively proven effective. There is clearly much work to be undertaken in this area.

Physiological features of cells and microvasculature under the local hypothermia influence

Hypothermia or cold therapy is the local or systemic application of cold for therapeutic purposes. Local application of cold is used to control inflammation: pain and swelling, hematoma and trismus reduction. Despite the frequent use of cooling in prosthodontic rehabilitation and in physical therapy, as evidenced by many reports in the literature, there is scientific documentation that suggests disadvantages of using this treatment in maxillofacial surgery and oral surgery. Also the clinical studies that have been carried out in maxillofacial surgery and oral surgery have been conducted in an empirical manner, which casts doubt on the results. In view of this, it is relevant to study the mechanisms of microcirculatory preconditioning and hypothermia. This physiological process is so interesting for the development of medical devices of controlled hardware hypothermia to prevent inflammatory symptoms at the stage of rehabilitation by targeting the vascular and cellular component of the inflammatory process in different areas of the human body. To date, the use of local hardware controlled hypothermia in various pathological conditions in humans is a topical trend in medicine. Microcirculatory bloodstream is directly related to temperature factors. Although there are concepts of vascular spasm or dilatation in the microcirculatory bloodstream during systemic hypothermia, there are no reliable data on the cellular and vascular reactions during local hypothermia. In this paper, a search for fundamental and current scientific work on the topic of cellular and vascular changes under the influence of hypothermia was conducted. The search for data revealed that the mechanisms of intracellular hypothermia are of particular interest for the development of therapeutic treatments after surgical interventions in areas with extensive blood supply. With this in mind, it is relevant to investigate several areas: the role of endothelium, glycocalyx and blood cells in microcirculatory-mediated preconditioning and intracellular hypothermia, and in the molecular mechanism that regulates these processes, whether they occur in the same way in all tissues.

Physiological features of cells and microvasculature under the local hypothermia influence

Hypothermia or cold therapy is the local or systemic application of cold for therapeutic purposes. Local application of cold is used to control inflammation: pain and swelling, hematoma and trismus reduction. Despite the frequent use of cooling in prosthodontic rehabilitation and in physical therapy, as evidenced by many reports in the literature, there is scientific documentation that suggests disadvantages of using this treatment in maxillofacial surgery and oral surgery. Also the clinical studies that have been carried out in maxillofacial surgery and oral surgery have been conducted in an empirical manner, which casts doubt on the results. In view of this, it is relevant to study the mechanisms of microcirculatory preconditioning and hypothermia. This physiological process is so interesting for the development of medical devices of controlled hardware hypothermia to prevent inflammatory symptoms at the stage of rehabilitation by targeting the vascular and cellular component of the inflammatory process in different areas of the human body. To date, the use of local hardware controlled hypothermia in various pathological conditions in humans is a topical trend in medicine. Microcirculatory bloodstream is directly related to temperature factors. Although there are concepts of vascular spasm or dilatation in the microcirculatory bloodstream during systemic hypothermia, there are no reliable data on the cellular and vascular reactions during local hypothermia. In this paper, a search for fundamental and current scientific work on the topic of cellular and vascular changes under the influence of hypothermia was conducted. The search for data revealed that the mechanisms of intracellular hypothermia are of particular interest for the development of therapeutic treatments after surgical interventions in areas with extensive blood supply. With this in mind, it is relevant to investigate several areas: the role of endothelium, glycocalyx and blood cells in microcirculatory-mediated preconditioning and intracellular hypothermia, and in the molecular mechanism that regulates these processes, whether they occur in the same way in all tissues.

Oxygen and brain death; back from the brink

NEW FINDINGS

• What is the topic of this review? To explore the unique evolutionary origins of the human brain and critically appraise its energy budget, including limits of oxygen and glucose deprivation during anoxia and ischaemia. • What advances does it highlight? The brain appears to be more resilient to substrate depletion than traditionally thought, highlighting greater resilience and an underappreciated capacity for functional recovery.

ABSTRACT

The human brain has evolved into an unusually large, complex and metabolically expensive organ that relies entirely on a continuous supply of O₂ and glucose. It has traditionally been assumed that its exorbitant energy budget, combined with little to no energy reserves, renders it especially vulnerable to anoxia and ischaemia, with substrate depletion and progression towards cell death largely irreversible and rapid. However, new and exciting evidence suggests that neurons can survive for longer than previously thought, highlighting an unexpected resilience and underappreciated capacity for functional recovery that has changed the way we think about brain cell death. Nature has the potential to unlock some of the mysteries underlying ischaemic survival, with select vertebrates having solved the problem of anoxia-hypoxia tolerance over millions of years of evolution. Better understanding of their survival strategies, including remarkable adaptations in brain physiology and redox homeostasis, might help to identify new therapeutic targets for human diseases characterized by O₂ deprivation, ischaemia-reperfusion injury and ageing.

Selective retrograde cerebral cooling in complete cerebral circulatory arrest

BACKGROUND AND PURPOSE:

Cerebral hypothermia is a known neuroprotectant with promising applications in the treatment of ischemic events. Although systemic cooling is standard in post-cardiac arrest care, the deleterious effects of whole-body cooling have precluded it from translation into a viable treatment option for acute ischemic stroke (AIS). Selective cerebral cooling has been proposed as a method to minimize these risks while granting the neuroprotection of therapeutic hypothermia in AIS.

METHODS:

In a porcine model (n = 3), the efficacy of selective retrograde cerebral cooling through the internal jugular vein was evaluated in the setting of complete cerebral circulatory arrest. Furthermore, a novel endovascular device and cooling system enabling selective retrograde cerebral cooling were studied in a normothermic perfused cadaver.

RESULTS AND CONCLUSION:

Neurologic assessment of animals receiving this therapy reflected substantial neuroprotection in animals undergoing both 15 min and 30 min of otherwise catastrophic complete cerebral circulatory arrest. The novel endovascular device and cooling system were validated in human anatomy, demonstrating successful cerebral cooling, and feasibility of this mechanism of selective retrograde cerebral cooling.