Ultra-rapid cooling and rewarming rate is a critical technical approach to achieve ice-free cells during the freezing and melting process. A set of ultra-rapid solid surface freeze-thaw visualization system was developed based on a sapphire flim, and experiments on droplet freeze-thaw were carried out under different cryoprotectant components, volumes and laser energies. The results showed that the cooling rate of 1 μL mixed cryoprotectant [1.5 mol/L propylene glycol (PG) + 1.5 mol/L ethylene glycol (EG) + 0.5 mol/L trehalose (TRE)] could be 9.2×10 ³ °C/min. The volume range of 1-8 μL droplets could be vitrified. After comparing the proportions of multiple cryoprotectants, the combination of equal proportion mixed permeability protectant and trehalose had the best vitrification freezing effect and more uniform crystallization characteristics. During the rewarming operation, the heating curve of glassy droplets containing gold nanoparticles was measured for the first time under the action of 400-1 200 W laser power, and the rewarming rate was up to the order of 10 ⁶ °C/min. According to the droplet images of different power rewarming processes, the laser power range for ice-free rewarming with micron-level resolution was clarified to be 1 400-1 600 W. The work of this paper simultaneously realizes the ultra-high-speed temperature ramp-up, transient visual observation and temperature measurement of droplets, providing technical means for judging the ice free droplets during the freeze-thaw process. It is conducive to promoting the development of ultra-rapid freeze-thaw technology for biological cells and tissues.
Freezing ; Vitrification ; Cryopreservation/methods* ; Trehalose ; Gold ; Rewarming ; Metal Nanoparticles ; Cryoprotective Agents ; Lasers

Objective To investigate the effect of systematic graded rewarming pattern on all-cause mortality of hypothermic trauma patients in different time periods. Methods A prospective case-control study was carried out for 236 hypothermic trauma patients with modified trauma score<12 in the Emergency Department of the Second Affiliated Hospital of Wenzhou Medical University from January 2020 to December 2021.The patients were randomly assigned into a systematic graded rewarming group (n=118) and a traditional rewarming group (n=118).The main outcome event was all-cause death within 15 days after trauma,and the secondary outcome event was all-cause death within 3,7,and 30 days after trauma. Results Overall,13.98%(33/236) and 14.83%(35/236) of the patients died within 15 and 30 days after trauma,respectively,and the median survival time of all dead patients was 6 (4,10) days.The systematic graded rewarming group had higher temperature after rewarming for 2 h (P=0.001) and larger temperature change after rewarming intervention (P=0.047) than the traditional rewarming group.The all-cause mortality within 15 days (27.3%vs.72.7%,P=0.005) and 30 days (25.7%vs.74.3%,P=0.002) in the systematic graded rewarming group was lower than that in the traditional rewarming group.Kaplan-Meier analysis showed that the survival time of the patients in the systematic graded rewarming group was longer than that in the traditional rewarming group (P=0.003).Multivariate cox regression analysis indicated that systematic graded rewarming was a strong protective factor for survival time after trauma (HR=0.450, P=0.042).Further Logistic regression analysis for the occurrence of all-cause death in each time period showed that the OR of systematic graded rewarming pattern to all-cause death within 15 days and 30 days after trauma were 0.289 and 0.286,respectively,after adjusting the covariates(P=0.008,P=0.005).The temperature after rewarming for 2 h had a negative correlation with all-cause mortality within 30 days after trauma (OR=0.670, P=0.049). Conclusions Systematic graded rewarming is a protective factor for the survival time of patients with traumatic hypothermia and an independent factor affecting the risk of all-cause death within 15 days and 30 days after trauma.The temperature after rewarming for 2 h is expected to be an independent predictor of all-cause mortality of 30 days after trauma in the patients with hypothermia.The systematic graded rewarming pattern could reduce the mortality of hypothermic trauma patients.
Humans ; Hypothermia ; Rewarming ; Case-Control Studies

OBJECTIVES: To investigate the clinical efficacy of mild therapeutic hypothermia (MTH) with different rewarming time on neonatal hypoxic-ischemic encephalopathy (HIE). METHODS: A prospective study was performed on 101 neonates with HIE who were born and received MTH in Zhongshan Hospital, Xiamen University, from January 2018 to January 2022. These neonates were randomly divided into two groups: MTH1 group (n=50; rewarming for 10 hours at a rate of 0.25°C/h) and MTH2 group (n=51; rewarming for 25 hours at a rate of 0.10°C/h). The clinical features and the clinical efficacy were compared between the two groups. A binary logistic regression analysis was used to identify the factors influencing the occurrence of normal sleep-wake cycle (SWC) on amplitude-integrated electroencephalogram (aEEG) at 25 hours of rewarming. RESULTS: There were no significant differences between the MTH1 and MTH2 groups in gestational age, 5-minute Apgar score, and proportion of neonates with moderate/severe HIE (P>0.05). Compared with the MTH2 group, the MTH1 group tended to have a normal arterial blood pH value at the end of rewarming, a significantly shorter duration of oxygen dependence, a significantly higher proportion of neonates with normal SWC on aEEG at 10 and 25 hours of rewarming, and a significantly higher Neonatal Behavioral Neurological Assessment score on days 5, 12, and 28 after birth (P<0.05), while there was no significant difference in the incidence rate of rewarming-related seizures between the two groups (P>0.05). There were no significant differences between the two groups in the incidence rate of neurological disability at 6 months of age and the score of Bayley Scale of Infant Development at 3 and 6 months of age (P>0.05). The binary logistic regression analysis showed that prolonged rewarming time (25 hours) was not conducive to the occurrence of normal SWC (OR=3.423, 95%CI: 1.237-9.469, P=0.018). CONCLUSIONS Rewarming for 10 hours has a better short-term clinical efficacy than rewarming for 25 hours. Prolonging rewarming time has limited clinical benefits on neonates with moderate/severe HIE and is not conducive to the occurrence of normal SWC, and therefore, it is not recommended as a routine treatment method.
Infant, Newborn ; Infant ; Child ; Humans ; Child, Preschool ; Prospective Studies ; Rewarming ; Hypoxia-Ischemia, Brain/therapy* ; Hypothermia, Induced/methods* ; Treatment Outcome ; Electroencephalography/methods*

OBJECTIVE: Cerebral hemodynamic and metabolic changes may occur during the rewarming phase of targeted temperature management in post cardiac arrest patients. Yet, studies on different rewarming rates and patient outcomes are limited. This study aimed to investigate post cardiac arrest patients who were rewarmed with different rewarming rates after 24 hours of hypothermia and the association of these rates to the neurologic outcomes.METHODS: This study retrospectively investigated post cardiac arrest patients treated with targeted temperature management and rewarmed with rewarming rates of 0.15°C/hr and 0.25°C/hr. The association of the rewarming rate with poor neurologic outcomes (cerebral performance category score, 3 to 5) was investigated.RESULTS: A total of 71 patients were analyzed (0.15°C/hr, n=36; 0.25°C/hr, n=35). In the comparison between 0.15°C/hr and 0.25°C/hr, the poor neurologic outcome did not significantly differ (24 [66.7%] vs. 25 [71.4%], respectively; P=0.66). In the multivariate analysis, the rewarming rate of 0.15°C/hr was not associated with the 1-month neurologic outcome improvement (odds ratio, 0.54; 95% confidence interval, 0.16 to 1.69; P=0.28).CONCLUSION: The rewarming rates of 0.15°C/hr and 0.25°C/hr were not associated with the neurologic outcome difference in post cardiac arrest patients.
Critical Care Outcomes ; Heart Arrest ; Hemodynamics ; Humans ; Hypothermia ; Multivariate Analysis ; Pilot Projects ; Retrospective Studies ; Rewarming

Therapeutic hypothermia (TH) improves the neurological outcome in patients after cardiac arrest and neonatal hypoxic brain injury. We studied the safety and feasibility of mild TH in patients with poor-grade subarachnoid hemorrhage (SAH) after successful treatment. Patients were allocated randomly to either the TH group (34.5°C) or control group after successful clipping or coil embolization. Eleven patients received TH for 48 hours followed by 48 hours of slow rewarming. Vasospasm, delayed cerebral ischemia (DCI), functional outcome, mortality, and safety profiles were compared between groups. We enrolled 22 patients with poor-grade SAH (Hunt & Hess Scale 4, 5 and modified Fisher Scale 3, 4). In the TH group, 10 of 11 (90.9%) patients had a core body temperature of < 36°C for > 95% of the 48-hour treatment period. Fewer patients in the TH than control group (n = 11, each) had symptomatic vasospasms (18.1% vs. 36.4%, respectively) and DCI (36.3% vs. 45.6%, respectively), but these differences were not statistically significant. At 3 months, 54.5% of the TH group had a good-to-moderate functional outcome (0–3 on the modified Rankin Scale [mRS]) compared with 9.0% in the control group (P = 0.089). Mortality at 1 month was 36.3% in the control group compared with 0.0% in the TH group (P = 0.090). Mild TH is feasible and can be safely used in patients with poor-grade SAH. Additionally, it may reduce the risk of vasospasm and DCI, improving the functional outcomes and reducing mortality. A larger randomized controlled trial is warranted.
Aneurysm ; Body Temperature ; Brain Injuries ; Brain Ischemia ; Embolization, Therapeutic ; Heart Arrest ; Humans ; Hypothermia, Induced* ; Mortality ; Pilot Projects* ; Prospective Studies* ; Rewarming ; Subarachnoid Hemorrhage* ; Vasospasm, Intracranial

PURPOSE: Therapeutic hypothermia is an important treatment strategy for control of the overwhelming inflammatory reactions of cardiac arrest patients. Rapid rewarming is related to poor outcome, however the kinds of inflammatory processes that occur during the rewarming period are not well understood. Our aim in the current study was to evaluate the changes in inflammatory cytokine levels during cardiac arrest patients' rewarming period. METHODS: This study was conducted in an emergency intensive care unit of a tertiary referral hospital. Blood samples were collected on admission (0 h) and 24, 26, 28, and 32 h after return of spontaneous circulation. Eight inflammatory cytokines (E-selectin, soluble ICAM, interleukin-10, interleukin-1ra, interleukin-6, interleukin-8, monocyte chemotactic protein-1, and tumor necrosis factor-α) were measured. RESULTS: Twenty-eight patients were enrolled and completed a protocol of 24 h hypothermia and 8h rewarming. Eight patients were of the good cerebral performance category (CPC) and 20 of the bad. The IL-1Ra level in the good CPC group was statistically changed at 26 (p=0.039) and 28 (p=0.003) but not at 32 h (p=0.632) when compared with the 24 h level. The IL-10 levels of the bad CPC group were decreased at 26 (p=0.017) and 28h (p=0.013) but not at 32 h (p=0.074) when compared with 24 h. None of the other cytokines showed meaningful differences during the rewarming period. CONCLUSION: Change in inflammatory-cytokine-level change during the rewarming period is not significant.
Chemokine CCL2 ; Cytokines* ; Emergencies ; Heart Arrest ; Humans ; Hypothermia ; Hypothermia, Induced* ; Intensive Care Units ; Interleukin 1 Receptor Antagonist Protein ; Interleukin-10 ; Interleukin-6 ; Interleukin-8 ; Necrosis ; Prognosis ; Rewarming* ; Tertiary Care Centers

OBJECTIVE: We investigated whether patients with out-of-hospital cardiac arrest (OHCA) due to an acute myocardial infarction without cardiogenic shock required higher doses of vasopressors with low targeted temperature management (TTM) after return of spontaneous circulation. METHODS: We included consecutive comatose patients resuscitated from OHCA between January 2011 and December 2013. Patients with return of spontaneous circulation, regional wall motion abnormality on echocardiography, and coronary artery stenosis of ≥70% on percutaneous coronary artery angiography were enrolled. These patients received 36°C TTM or 33°C TTM following approval of TTM by patients’ next-of-kin (36°C and 33°C TTM groups, respectively). The cumulative vasopressor index was compared between groups. RESULTS: During induction phase, dose of vasopressors did not differ between groups. In the maintenance phase, the norepinephrine dose was 0.37±0.57 and 0.26±0.91 µg·kg⁻¹·min⁻¹ in the 33°C and 36°C TTM groups, respectively (P<0.01). During the rewarming phase, the norepinephrine and dopamine doses were 0.49±0.60 and 9.67±9.60 mcg·kg⁻¹·min⁻¹ in the 33°C TTM group and 0.14±0.46 and 3.13±7.19 mcg·kg⁻¹·min⁻¹ in the 36°C TTM group, respectively (P<0.01). The median cumulative vasopressor index was 8 (interquartile range, 3 to 8) and 4 (interquartile range, 0 to 8) in the 33°C and 36°C TTM groups, respectively (P=0.03). CONCLUSION: In this study, patients with OHCA due to acute myocardial infarction without cardiogenic shock had an elevated vasopressor requirement with 33°C TTM compared to 36°C TTM during the maintenance and rewarming phases.
Angiography ; Coma ; Coronary Stenosis ; Coronary Vessels ; Dopamine ; Echocardiography ; Humans ; Hypothermia ; Myocardial Infarction* ; Norepinephrine ; Out-of-Hospital Cardiac Arrest* ; Rewarming ; Shock, Cardiogenic* ; Vasoconstrictor Agents

STUDY DESIGN: A retrospective study. PURPOSE: The aim of this study was to evaluate the effects of delayed hypothermia on spinal cord injuries in rats. In addition, the effect of methylprednisolone on therapeutic window of hypothermia was evaluated. OVERVIEW OF LITERATURE: Several studies have demonstrated that early hypothermia is the most effective neuroprotective modality. However, delayed hypothermia seems to be more practical for patients with traumatic spinal cord injuries. A combination of hypothermia and other neuroprotective methods, such as using methylprednisolone, may help extend the therapeutic window of hypothermia. METHODS: One hundred and twenty male rats were categorized into six groups. The rats in five groups were subjected to spinal cord injury using the weight drop method, followed by treatment, consisting of early hypothermia, late hypothermia, late hypothermia plus methylprednisolone, or methylprednisolone only. Biochemical tests including catalase, malondialdehyde, and superoxide level were evaluated in the injured spinal cord. Behavioral functions of the hind limb were evaluated by Basso-Battle-Bresnaham locomotor rating scale and tail-flick tests. RESULTS: Functional and biochemical evaluation showed both early and late hypothermia had significant neuroprotective effects. The treated groups did not differ significantly from one another in the behavioral tests. Hypothermia had better biochemical results compared to methylprednisolone. Also, methylprednisolone was shown to extend the therapeutic window of delayed hypothermia. CONCLUSIONS: Hypothermia showed a significant neuroprotective effect, which can be improved with further studies optimizing the duration of hypothermia and the rewarming period. Moreover, the therapeutic effect of the delayed hypothermia can be extended by methylprednisolone.
Animals ; Catalase ; Extremities ; Humans ; Hypothermia* ; Male ; Malondialdehyde ; Methylprednisolone* ; Neuroprotective Agents* ; Rats* ; Retrospective Studies ; Rewarming ; Spinal Cord ; Spinal Cord Injuries* ; Superoxides

PURPOSE: Therapeutic hypothermia (TH) has become a standard strategy for reducing brain damage in the postresuscitation period. The aim of this study is to investigate the outcomes and current performance of TH with out-of-hospital cardiac arrest (OHCA) survivors through the Korean hypothermia network (KORHN) registry. METHODS: We used the KORHN registry, a web-based, multicenter registry that includes 24 participating hospitals throughout the Republic of Korea. Adult comatose OHCA survivors treated with TH from 2007 to 2012 were included. The primary outcomes were neurologic outcome at hospital discharge and in-hospital mortality. The secondary outcomes were TH performance and adverse events during TH. RESULTS: A total of 930 patients were included; of these, 556 (59.8%) patients survived to discharge and 249 (26.8%) were discharged with good neurologic outcomes. The median time from return of spontaneous circulation (ROSC) to the start of TH was 101 (interquartile range (IQR): 46-200) minutes. The induction, maintenance, and rewarming durations were 150 (IQR: 80-267) minutes, 1440 (IQR: 1290-1440) minutes, and 708 (IQR: 420-900) minutes, respectively. The time from the ROSC to coronary angiography was 1,045 (IQR: 121-12,051) hours. Hyperglycemia (46.3%) was the most frequent adverse event. CONCLUSION: Over one quarter of OHCA survivors (26.8%) were discharged with good neurologic outcome. TH performance was managed appropriately in terms of the factors related to the timing of TH, which were the start time for cooling and the rewarming duration.
Adult ; Brain ; Coma ; Coronary Angiography ; Hospital Mortality ; Humans ; Hyperglycemia ; Hypothermia* ; Hypothermia, Induced ; Korea ; Out-of-Hospital Cardiac Arrest* ; Registries ; Republic of Korea ; Rewarming ; Survivors

BACKGROUND: Rapid fluid warming has been a cardinal measure to maintain normothermia during fluid resuscitation of hypovolemic patients. A previous laboratory simulation study with different fluid infusion rates showed that a fluid warmer using magnetic induction is superior to a warmer using countercurrent heat exchange. We tested whether the simulation-based result is translated into the clinical liver transplantation. METHODS: Two hundred twenty recipients who underwent living donor liver transplantation between April 2009 and October 2011 were initially screened. Seventeen recipients given a magnetic induction warmer (FMS2000) were matched 1 : 1 with those given a countercurrent heat exchange warmer (Level-1 H-1000) based on propensity score. Matched variables included age, gender, body mass index, model for end-stage liver disease score, graft size and time under anesthesia. Core temperatures were taken at predetermined time points. RESULTS: Level-1 and FMS groups had comparable core temperature throughout the surgery from skin incision, the beginning/end of the anhepatic phase to skin closure. (P = 0.165, repeated measures ANOVA). The degree of core temperature changes within the dissection, anhepatic and postreperfusion phase were also comparable between the two groups. The minimum intraoperative core temperature was also comparable (Level 1, 35.6degrees C vs. FMS, 35.4degrees C, P = 0.122). CONCLUSIONS: A countercurrent heat exchange warmer and magnetic induction warmer displayed comparable function regarding the maintenance of core temperature and prevention of hypothermia during living donor liver transplantation. The applicability of the two devices in liver transplantation needs to be evaluated in various populations and clinical settings.
Anesthesia ; Body Mass Index ; Body Temperature Changes ; Hot Temperature ; Humans ; Hypothermia ; Hypovolemia ; Liver Diseases ; Liver Transplantation* ; Living Donors* ; Propensity Score ; Resuscitation ; Rewarming ; Skin ; Transplants