Arrest Temperature Research Articles

Optimal circulatory arrest temperature for total aortic arch replacement: outcomes of neurological complications

BackgroundThe optimal hypothermic circulatory arrest (HCA) temperature during total arch replacement (TAR) and the impact of HCA temperature on postoperative neurological complications are still uncertain. ObjectiveThe aim of this study is to explore the impact of HCA temperature on short-term postoperative outcomes, especially neurological complications, for patients who undergo TAR. MethodsWe retrospectively analyzed data of 2351 patients who underwent TAR at one of seven selected aortic centers from January 2016 to June 2023. Restricted cubic splines (RCS) and subgroup analyses were performed to determine the relation between temperature and outcomes under different cerebral perfusion methods, cannulation strategies, diagnoses, and surgical timings. ResultsThe overall in-hospital mortality was 6.2% (n = 146). The incidence of stroke, paraplegia and total-arch composite outcome (TCO) was 6.0% (n = 142), 2.8% (n = 65) and 21.0% (n = 494), respectively. The average HCA temperature was 25.9 ± 1.9 °C, and the median circulatory arrest time was 23 (Q1, Q3: 18, 30) min. Adjusted RCS showed the lowest incidence of stroke, paraplegia, and TCO at temperatures of 26.6 °C, 27.4 °C, and 26.8 °C, but without statistical significance. In subgroup analysis, the unilateral antegrade cerebral perfusion (uACP) group revealed a significant nonlinear relation between HCA temperature and the risk of stroke, and the lowest risk showed at 26.5 °C. Other subgroup analyses did not reveal a significant nonlinear relation between temperature and outcomes. ConclusionsFor patients undergoing TAR with uACP, cooling to a temperature of 26-27 °C was associated with the lowest incidence of stroke.

Abstract Su1202: The utility of post cardiac arrest temperature control protocol according to the severity of hypoxic encephalopathy based on amplitude-integrated electroencephalography findings

Introduction: The TTM2 trial showed that active fever prevention below 37.5°C and hypothermia at 33°C had similar outcomes in out-of-hospital post cardiac arrest patients. However, the patients in the trial had mild hypoxic encephalopathy, and the effects of hypothermia may vary with its severity. We previously reported that amplitude-integrated electroencephalography (aEEG) findings after the return of spontaneous circulation can be used to categorize the severity of hypoxic encephalopathy (Crit Care. 2018;22:226). In September 2022, we adopted a new temperature control protocol wherein the target temperature was set based on aEEG findings. This study examined changes in outcomes before and after implementing this new protocol. Methods: We assessed out-of-hospital cardiac arrest patients who received post cardiac arrest care in our emergency intensive care unit between March 2021 and February 2024. We divided the patients into two groups: before (B) and after (A) the introduction of the new protocol. We classified the patients into categories 1 (C1) to 4 (C4) based on the severity of hypoxic encephalopathy (Figure 1). All patients in group B were treated with hypothermia at 34°C. In group A, patients in C1 were treated with active fever prevention, and those in C2–C4 received hypothermia at 34°C (Figure 2). Primary outcome was favorable neurological outcomes (cerebral performance categories of 1 or 2) at hospital discharge. Secondary outcome was the duration of mechanical ventilation. Results: A total of 160 patients were included. The median age was 62 years and 105 (66%) patients had cardiac etiology. Fifty-five (34%) patients underwent extracorporeal cardiopulmonary resuscitation. The median cardiac arrest time was 29 min. Groups B and A comprised 57 and 103 patients, respectively. C1 category comprised 20 and 28 patients in groups B and A, respectively. The rate of favorable neurological outcomes was 35% in both B and A groups (p=1.00). Regarding C1 patients, the rates were 90% and 86% in B and A groups (p=1.00). Median duration of mechanical ventilation was 5 and 3 days in group B and A, respectively (p=0.11). Conclusion: Neurological outcomes before and after introducing the new protocol were similar. Management of patients with mild hypoxic encephalopathy can be simplified with active fever prevention. A temperature control protocol based on the severity of hypoxic encephalopathy using aEEG findings is feasible for emergency physicians.

Practice survey on recent changes in post cardiac arrest care and temperature management in French intensive care units

BackgroundRecent guidelines for post-cardiac arrest (CA) management have undergone significant changes regarding targeted therapeutic management (TTM), transitioning from hypothermia to temperature control. We aimed to assess changes in post-CA management in French intensive care units following the new recommendations. MethodsTwo declarative web surveys were conducted from March to August 2023. We compared the doctors' survey to that previously published in 2015. We contacted 389 departments from 276 French centers. ResultsThree hundred thirty-four physicians from 189 distinct ICUs departments participated in the survey. TTM was used by 95.5 % of respondents. TTM with temperature feedback device was used by 64 % of respondents. In multivariate analysis, use of TTM with temperature feedback was associated with university hospital responder [OR 1.99 (1.19–3.34, p = 0.009)], high CA admissions rate [OR 2.25 (1.13–4.78, p = 0.026)], use of a written CA procedure [OR 1.76 (1.07–2.92, p = 0.027)] and presence of a cath-lab performing coronary angiography [OR 2.42 (1.33–4.44, p = 0.004)]. The targeted temperature rose from 32 to 34 °C in 2015, to 35–36 °C in 2023 (p < 0.001). Proportions of TTM with temperature feedback devices switched from 45 % to 65 % (p < 0.001). 660 nurses responses from 150 ICUs were analyzed. According to TTM users, gel-coated water circulating pads and intravascular cooling were considered the most effective devices and were found to be easily adjustable. ConclusionsThese surveys provide insights into post-resuscitation care and TTM practice in France. One year after their publication, the latest recommendations concerning TTM have not been fully implemented, as the majority of ICUs continue to use moderate hypothermia. They widely reported employing specific TTM, with the use of TTM with temperature feedback devices increasing significantly. Heterogeneity exists regarding the TTM systems used, with a significant proportion lacking temperature feedback. This aspect requires specific attention, depending on local constraints and devices costs.

The optimal degree of core temperature for hypothermic circulatory arrest in complex aortic arch surgery: results from 1310 patients.

The optimal core temperature for hypothermic circulatory arrest during aortic arch surgery remains contentious. This study aims to evaluate patient outcomes under various temperatures within a large single-centre cohort. Between 2010 and 2018, patients diagnosed with type A aortic dissection underwent total arch replacement at Fuwai Hospital were enrolled. They were categorized into 4 groups: deep hypothermia group, low-moderate hypothermia group, high-moderate hypothermia group and mild hypothermia group. Clinical data were analysed to ascertain differences between the groups. A total of 1310 patients were included in this cohort. Operative mortality stood at 6.9% (90/1310), with a higher incidence observed in the deep hypothermia group [29 (12.9%); 35 (6.9%); 21 (4.8%); 5 (3.4%); all adjusted P < 0.05]. Overall 10-year survival was 80.3%. Long-term outcomes did not significantly differ among the groups. Multivariable logistic analysis revealed a protective effect of higher core temperature on operative mortality (odds ratio 0.848, 95% confidence interval 0.766-0.939; P = 0.001). High-moderate hypothermia emerged as an independent protective factor for operative mortality (odds ratio 0.303, 95% confidence interval 0.126-0.727; P = 0.007). Multivariable Cox analysis did not detect an effect of hypothermic circulatory arrest on long-term survival (all P > 0.05). High-moderate hypothermia (24.1-28°C) offers the most effective protection against surgical mortality and is therefore recommended. Different hypothermic circulatory arrest temperatures do not influence long-term survival or quality of life.

Brittle Crack Arrest Temperature Estimation Method Utilizing a Small-Scale Test with a Thick Steel Plate for Shipbuilding

As the shipbuilding industry has emerged from an extended recession, orders for high-value-added ships, such as LNG and ultra-large container ships, are increasing. For ultra-large container ships, high-strength, thick materials are applied. Because the possibility of brittle fracture increases owing to the application of thick steel plates, the related regulations of the International Association of Classification Societies have been strengthened to prevent brittle fracture. To secure brittle fracture stability, it is necessary to secure crack arrest toughness (Kca) through large ESSO experiments or to secure a crack arrest temperature (CAT) value. Because large-scale experiments require considerable costs and efforts, efforts have increased to examine brittle fracture stability through small-scale tests. In the present study, a technology was developed to predict CAT with small specimens. The CAT prediction formula developed with small specimens makes it possible to accurately predict CAT using data obtained through large-scale experiments.

Factors Associated with Favorable Outcomes in Cardiac Arrest and Target Temperature Management.

Current guidelines strongly recommend providing targeted temperature management (TTM) after cardiac arrest, but hypothalamic dysregulation may confound TTM's impact on a patient's ultimate outcome. Although time to reach target temperature has largely been viewed as a process measure for TTM protocols, the difference between initial presenting temperature and target temperature (Δ-temperature) may be a potential surrogate marker of hypothalamic dysregulation. We performed a retrospective observational study to explore whether Δ-temperature was associated with neurologic outcomes and mortality. We included 86 patients (53 with out-of-hospital cardiac arrest [OHCA] and 33 with in-hospital cardiac arrest [IHCA]) in our analysis; more than half of the patients were cooled to 33°C (56.9% in OHCA and 57.6% in IHCA). In univariate logistic regression analysis, Δ-temperature alone did not appear to be statistically associated with mortality or neurologic outcomes regardless of target temperature. In exploratory analysis, longer time from TTM initiation-to-target was associated with worse neurological outcomes in the 33°C target (odds ratio = 0.996, 95% confidence interval = 0.992-1.000). Further research investigating the impact of hypothalamic dysregulation and Δ-temperature as well as the rate of cooling may be warranted to elucidate additional factors contributing to outcomes after cardiac arrest. In addition, our study population was noted to have a higher proportion of Asians and Native Hawaiians/Pacific Islanders, with a potential disparity in outcomes. Future studies may be warranted to ensure generalizability of TTM protocols and findings across populations.

Precipitated wax content and yield stress of model wax-oil mixtures determined by arrest of flow during cooling at fixed stress

To estimate yield stress and other rheological properties relevant to modeling of wax deposition in pipelines where flow is continuous, but stress varies across the pipe radius, model wax-oil mixtures are cooled at multiple cooling rates under constant shear stress until a temperature is reached, at which flow is arrested by gelation due to wax crystal formation. From these data, combined with a measurement of temperature-dependence of precipitated wax concentration by differential scanning calorimetry, an apparent yield stress σy, below which flow is arrested at each temperature, is related to the concentration of precipitated wax Cp and the cooling rate. Results are reported for multiple concentrations in oil of two independent wax mixtures: a many-component commercial wax mimicking the composition of field oil, and a simpler six-alkane mixture. These transient rheological data are fit to a pseudo “Herschel–Bulkley” constitutive equation from which it is found that the yield stresses obtained during flow under cooling are generally an order of magnitude, or more, lower than the yield stresses obtained in the previous work in flow at a comparable constant temperature after cooling in the absence of flow. We also find a strong decrease in the arrest temperature with a decreasing cooling rate, with no convergence even at the lowest cooling rate of 0.0625 °C min−1, indicating that under slower cooling, flow continues even under low stresses. The cooling-rate-dependent yield stress obtained in our study under constant stress provides a challenge to the recent models of gelation under flow stress and is of relevance to wax deposition in pipelines.

Rewarming Young Children After Drowning-Associated Hypothermia and Out-of-Hospital Cardiac Arrest: Analysis Using the CAse REport Guideline.

Extracorporeal membrane oxygenation (ECMO) is recommended in adults with drowning-associated hypothermia and out-of-hospital cardiac arrest (OHCA). Our experience of managing a drowned 2-year-old girl with hypothermia (23°C) and cardiac arrest (58 min) prompted this summary using the CAse REport (CARE) guideline to address the question of optimal rewarming procedure in such patients. Following the CARE guideline, we identified 24 reports in the "PubMed database" describing children less than or equal to 6 years old with a temperature less than or equal to 28°C who had been rewarmed using conventional intensive care ± ECMO. Adding our patient, we were able to analyze a total of 57 cases. The two groups (ECMO vs non-ECMO) differed with respect to submersion time, pH and potassium but not age, temperature or duration of cardiac arrest. However, 44 of 44 in the ECMO group were pulseless on arrival versus eight of 13 in the non-ECMO group. Regarding survival, 12 of 13 children (92%) undergoing conventional rewarming survived compared with 18 of 44 children (41%) undergoing ECMO. Among survivors, 11 of 12 children (91%) in the conventional group and 14 of 18 (77%) in the ECMO group had favorable outcome. We failed to identify any correlation between "rewarming rate" and "outcome." In this summary analysis, we conclude that conventional therapy should be initiated for drowned children with OHCA. However, if this therapy does not result in return of spontaneous circulation, a discussion of withdrawal of intensive care might be prudent when core temperature has reached 34°C. We suggest further work is needed using an international registry.

Temperature control in adults after cardiac arrest: a survey of current clinical practice in Germany

BackgroundTemperature control is recommended after out of hospital cardiac arrest (OHCA) by international guidelines. This survey aimed to investigate current clinical practice and areas of uncertainty.MethodsOnline survey targeting members of three medical emergency and critical care societies in Germany (April 21–June 6, 2022) assessing post-cardiac arrest temperature control management.ResultsOf 341 completed questionnaires 28% (n = 97) used temperature control with normothermic target and 72% (n = 244) temperature control with hypothermic target. The definition of fever regarding patients with cardiac arrest ranged from ≥ 37.7 to 39.0 °C. Temperature control was mainly started in the ICU (80%, n = 273) and most commonly core cooling (74%, n = 254) and surface cooling (39%, n = 134) with feedback were used. Temperature control was maintained for 24 h in 18% (n = 61), 48 h in 28% (n = 94), 72 h in 42% (n = 143) and longer than 72 h in 13% (n = 43). 7% (n = 24) were using different protocols for OHCA with initial shockable and non-shockable rhythm. Additional 14% (n = 48) were using different temperature control protocols after in-hospital cardiac arrest (IHCA) compared with OHCA. Overall, 37% (n = 127) changed practice after the publication of the ERC-2021 guidelines and 33% (n = 114) after the recent publication of the revised ERC-ESICM guideline on temperature control.ConclusionsOne-third of the respondents changed clinical practice since recent guideline update. However, a majority of physicians further trusts in temperature control with a hypothermic target. Of interest, 14% used different temperature control strategies after IHCA compared with OHCA and 7% for shockable and non-shockable initial rhythm. A more individualized approach in post resuscitation care may be warranted.

Organ damage evaluation in a temperature-controlled circulatory arrest rat model

BackgroundDeep hypothermic circulatory arrest (DHCA) is commonly used in adult aortic surgery and pediatric complex congenital heart disease, and is associated with pathophysiological changes and postoperative complications. Here, a temperature-controlled circulatory arrest model in rats was established to study the suitable temperature of circulatory arrest by investigating the damage to body organs under different temperatures.MethodsThirty Sprague‒Dawley rats were randomly divided into 5 equal groups for DHCA experiments: I (15–20 °C), II (20–25 °C), III (25–30 °C), IV (normothermic cardiopulmonary bypass), and V (sham operation group). Blood gas analysis, homodynamic parameters, and intervals of cardiac recovery were measured at different time points in all groups. Morphological changes in intestinal tissue were observed under light and electron microscopes. Oxidative stress was measured by MPO activity, MDA, and SOD content. Tissue damage was confirmed by serum detection of ALT, AST, BUN, Cr, and LDH. To examine the inflammatory response, cytokines, including IL-1, IL-4, IL-10, IFN-γ, and TNF-α, were detected.ResultsThe extracorporeal circulation technique caused damage to the body; the degree of the damage caused by the circulatory arrest technique may be related to circulating temperature, with the least amount of damage occurring at 20–25 °C compared to 15–20 °C and 25–30 °C. Ischemia and hypoxia can cause intestinal tissue damage, which manifests primarily as a loss of the intestinal mucosal barrier. Ischemic intestinal damage caused by DHCA was not associated with inflammation.ConclusionThe study provides new insights into the pathophysiologic mechanisms of DHCA.

Thermal FEM Analysis of Surge Arresters During HVdc Current Interruption Validated by Experiments

This paper deals with the development of an accurate finite-element model of an arrester to investigate the electrothermal and mechanical stress during dc current interruption. The comprehensive analysis performed on a ZnO surge arrester is supported by experiments during high-voltage dc circuit breaker current interruption. The performed experimental analysis comprises three sequential 26 kV/10 kA direct current interruption tests carried out within a period of one hour. The dynamic temperature and current distribution of the surge arrester columns during current interruption are measured. The finite-element simulation results are in good agreement with the test results. The influence of the surge arrester temperature on the current distribution among the surge arrester columns is analyzed. The impact of the surge arrester temperature on ZnO electrical characteristics and mechanical stress inside the surge arrester are also investigated. The surge arrester finite-element model can be used with full success for parameter optimization of the surge arresters to prevent possible failures when dc circuit breakers performed multiple interruptions in short period of time.

Study on operation voltage monitoring and electrothermal coupling simulation of electric multiple unit (EMU) roof arrester

The roof arrester of electric multiple units (EMU) can efficiently limit the overvoltage, and ensure the safe operation of the EMU electrical equipment. In the process of high-speed operation, the traction power supply system is often affected by overvoltage. In addition, roof arrester explosion accidents occasionally occur. In this paper, the on-line voltage measurement system of the EMU arrester is developed. By analysing a large number of voltage waveforms, the abnormal voltage is divided into three categories: over-phase voltage, high harmonic voltage and steep impulse overvoltage. The characteristics of abnormal voltage waveforms are then summarised. The electrothermal coupling simulation model of the arrester is developed, and the current response and temperature distribution of the arrester under abnormal voltage are calculated. The impact of the impulse voltage energy on the arrester temperature is studied by applying a triangular wave voltage to the model. Finally, some suggestions are proposed for the operation and maintenance of the roof arrester.

Safety Time and Optimal Temperature of Unilateral Antegrade Cerebral Perfusion in Acute Type A Aortic Dissection: A Single-Center 15-Year Experience.

The optimal level of hypothermia and safe time of unilateral antegrade cerebral perfusion (uACP) in acute type A aortic dissection (ATAAD) repair remain controversial. To analyze the association of uACP time and circulatory arrest temperature with surgical outcomes of ATAAD. We retrospectively analyzed 263 patients who had undergone ATAAD repair between 2006 and 2020 using uACP. The patients were stratified by three chronologically equivalent periods (period 1, 2006 to 2010; period 2, 2011 to 2015; period 3, 2016 to 2020) to demonstrate the decade-long evolution of surgical strategy and outcomes. The mean age of the patients was 59.4 ± 12.5 years, and 68.8% were male. The hospital mortality rates were 15.1%, 12.9%, and 11.0% from period 1 to 3 (p = 0.740). The median circulatory arrest temperatures were 20, 23, and 25 °C (p < 0.001), respectively, and the median uACP times were 72, 59, and 41 minutes (p < 0.001). The incidence rates of postoperative permanent neurologic deficits were 13.2%, 10.9%, and 18.3% (p = 0.312), and those of transient neurologic deficits were 9.4%, 10.9%, and 11.9% (p = 0.936), respectively. Multivariate logistic regression analysis showed that uACP time ≥ 60 minutes was an independent predictor of hospital mortality rather than postoperative stroke. ROC curve analysis estimated an optimal cutoff value of 52 minutes of uACP time when the circulatory arrest temperature was ≥ 25 °C to predict hospital mortality (area under the curve: 0.72). Unilateral antegrade cerebral perfusion time was associated with hospital mortality after ATAAD surgery. A safe threshold of 50 to 60 minutes of uACP should be considered.

Accidental Hypothermia: 2021 Update.

Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousands die of primary hypothermia and an unknown number die of secondary hypothermia worldwide. Hypothermia can be expected in emergency patients in the prehospital phase. Injured and intoxicated patients cool quickly even in subtropical regions. Preventive measures are important to avoid hypothermia or cooling in ill or injured patients. Diagnosis and assessment of the risk of cardiac arrest are based on clinical signs and core temperature measurement when available. Hypothermic patients with risk factors for imminent cardiac arrest (temperature < 30 °C in young and healthy patients and <32 °C in elderly persons, or patients with multiple comorbidities), ventricular dysrhythmias, or systolic blood pressure < 90 mmHg) and hypothermic patients who are already in cardiac arrest, should be transferred directly to an extracorporeal life support (ECLS) centre. If a hypothermic patient arrests, continuous cardiopulmonary resuscitation (CPR) should be performed. In hypothermic patients, the chances of survival and good neurological outcome are higher than for normothermic patients for witnessed, unwitnessed and asystolic cardiac arrest. Mechanical CPR devices should be used for prolonged rescue, if available. In severely hypothermic patients in cardiac arrest, if continuous or mechanical CPR is not possible, intermittent CPR should be used. Rewarming can be accomplished by passive and active techniques. Most often, passive and active external techniques are used. Only in patients with refractory hypothermia or cardiac arrest are internal rewarming techniques required. ECLS rewarming should be performed with extracorporeal membrane oxygenation (ECMO). A post-resuscitation care bundle should complement treatment.

Effect of &lt;i&gt;β&lt;/i&gt; lath arrangement on activation of &lt;a&gt; slips in single-colony lamellar structures of Ti-6Al-4V alloy

Micro-tensile tests using single-colony specimens of Ti-6Al-4V alloy with a fine lamellar microstructure were employed in the temperature range between 298 and 423 K to understand the effects of geometrical orientation of β lath on <a> slip behaviour. The critical resolved shear stress (CRSS) for the basal slips was lower than that of the prismatic slips, in addition, the temperature dependence of the slip behaviour was greater in the basal slips than the prismatic slips. In the case of single α phase excluding β lath, the CRSS and temperature dependence are independent of the slip modes. In the lamellar microstructure, however, the basal slip propagates simultaneously through all the lamellar layers (divider type) and the prismatic slip propagates sequentially from one layer to another (arrester type). Therefore, considering that dislocation motion is restricted through the pinning and pile-up mechanisms in divider and arrester orientations, respectively, the CRSS and temperature dependence in the basal and prismatic slips can be explained by the geometrical orientation of β lath included in lamellae. This finding suggests that the geometric configuration of β lath dominates the <a> slip in single-colony lamellar structure of the Ti-6Al-4V alloy.

Total Aortic Arch Replacements With a 4 Branched Frozen Elephant Trunk (FET) Graft in Acute Aortic Dissection (DeBakey type I)

Total Aortic Arch Replacements With a 4 Branched Frozen Elephant Trunk (FET) Graft in Acute Aortic Dissection (DeBakey type I)

Optimal circulatory arrest temperature for aortic hemiarch replacement with antegrade brain perfusion

ObjectiveThis study sought to identify the optimal temperature for moderate hypothermic circulatory arrest in patients undergoing elective hemiarch replacement with antegrade brain perfusion. MethodsThe Society of Thoracic Surgeons adult cardiac surgery database was queried for elective hemiarch replacements using antegrade brain perfusion for aneurysmal disease (2014-2019). Generalized estimating equations and restricted cubic splines were used to determine the risk-adjusted relationships between temperature as a continuous variable and outcomes. ResultsElective hemiarch replacement with antegrade brain perfusion occurred in 3898 patients at 374 centers with a median nadir temperature of 24.9°C (first quartile, third quartile = 22.0°C, 27.5°C) and median circulatory arrest time of 19 minutes (first quartile, third quartile = 14.0 minutes, 27.0 minutes). After adjustment for comorbidities, circulatory arrest time, and individual surgeon, patients cooled between 25 and 28°C had an early survival advantage compared with 24°C, whereas those cooled between 21 and 23°C had higher risks of mortality compared with 24°C. A nadir temperature of 27°C was associated with the lowest risk-adjusted odds of mortality (odds ratio, 0.62; 95% confidence interval, 0.42-0.91). A nadir temperature of 21°C had the highest risk of mortality (odds ratio, 1.4; 95% confidence interval, 1.13-1.73). Risk of experiencing a major morbidity was elevated in patients cooled between 21 and 23°C, with the highest risk occurring in patients cooled to 21°C (odds ratio, 1.12; 95% confidence interval, 1.01-1.24). ConclusionsFor patients with aneurysmal disease undergoing elective hemiarch with antegrade brain perfusion, circulatory arrest with a nadir temperature of 27°C confers the greatest early survival benefit and smallest risk of postoperative morbidity.

Long-Term Out come Evaluation in Patient Undergoing Deep Hypo-thermic Circulatory Arrest in Aortic Arch Surgery

Background: Aortic dissection is usually associated with low survival rates due to high prehospital and perioperative mortality, in addition with increased risk of postoperative complication in survivals. Since 1985, deep hypothermic circulatory arrest (DHCA) is often used in aortic arch surgery with main advantage to provide bloodless surgical field while protecting brain tissue during hypothermia. Nevertheless, it still raises concern of increasing neurologic sequelae and a potential decrease of long-term quality of life. The aim of study: To evaluate the effect of DHCA used in aortic surgery on long-term quality of life. Methods: In this observational case series we included a total of 24 patients who had aortic arch surgery requiring DHCA in the Pauls Stradins Clinical University Hospital Cardiac Surgery center, from January 2019 to December 2020. Seven patients were excluded due to intrahospital death. For the rest of the patients Quality of life (QOL) was evaluated using RAND SF36 questionnaire and MMSE test. Data regarding demographics, clinical characteristics, surgery type, duration of circulatory arrest, rectal and bladder temperatures were collected and analyzed using the SPSS 23 Statistics software IBM SPSS Statistics 21 (IBM Corporation, NY, USA). Statistical significance was assumed as two- tailed p &lt;0.05. Results: A total of 17 patients were analyzed, we had 12 (71%) males and 5 (29%) females. A mean age was 60.71 (±13.8 SD) years, leading co-morbidity was hypertension – 11 (64.7%). There were 6 (35.3%) elective and 11 (64.7%) acute surgeries. Stan-ford A dissection (82.4%) constituted the main part of all cases. A 94.7% had aortic arch replacement. Most common postopera-tive complication was wound infection- 29.4%. The mean cardiopulmonary bypass time, aortic cross-clamping and reperfusion time was 212 (±38.3, SD), 124 (±33.8, SD) and 70.2 (±32.9, SD) minutes, respectively. Core temperature during DHCA was 23.2 Cº (±3.2, SD) and a rewarming rate was 0.12 (±0.07, SD) Cº/min. No significance correlation between RAND SF36 questionnaire score (QoL questionnaire) and lowest DHCA temperature, aortic cross - clamping, reperfusion time, CPB time was observed, respectively - p=0.367, p=0.544, p=0.619, p=0. We found statistically significant moderate strength correlation between QOL and rewarming rate (r=0.550; p=0.022). Mean RAND SF36 questionnaire score was 71.9±10. and mean MMSE score was 27.9±5,3. Conclusions: We found no correlation between quality of life and lowest temperature during surgery, aortic cross- clamping time, reperfusion time, however we found positive moderate strength correlation between rewarming rate and quality of life. Patient quality of life after surviving aortic arch surgery and deep hypothermic circulatory arrest compared to general healthy population quality of life is slightly reduced. Mini-mental state exam and RANDO short form health survey can be useful scoring system to evaluate patient quality of life.

Does deeper hypothermia reduce the risk of acute kidney injury after circulatory arrest for aortic arch surgery?

The impact of hypothermic circulatory arrest (HCA) temperature on postoperative acute kidney injury (AKI) has not been evaluated. This study examined the association between circulatory arrest temperatures and AKI in patients undergoing proximal aortic surgery with HCA. A total of 759 consecutive patients who underwent proximal aortic surgery (ascending ± valve ± root) including arch replacement requiring HCA between July 2005 and December 2016 were identified from a prospectively maintained institutional aortic surgery database. The primary outcome was AKI as defined by Risk, Injury, Failure, Loss, End Stage Renal Disease (ESRD) criteria. The association between minimum nasopharyngeal (NP) and bladder temperatures during HCA and postoperative AKI was assessed, adjusting for patient-level factors using multivariable logistic regression. A total of 85% (n = 645) of patients underwent deep hypothermia (14.1-20.0°C), 11% (n = 83) low-moderate hypothermia (20.1-24.0°C) and 4% (n = 31) high-moderate hypothermia (24.1-28.0°C) as classified by NP temperature. When analysed by bladder temperature, 59% (n = 447) underwent deep hypothermia, 22% (n = 170) low-moderate, 16% (n = 118) high-moderate and 3% mild (n = 24) (28.1-34.0°C) hypothermia. The median systemic circulatory arrest time was 17 min. The incidence of AKI did not differ between hypothermia groups, whether analysed using minimum NP or bladder temperature. In the multivariable analysis, the association between degree of hypothermia and AKI remained non-significant whether analysed as a categorical variable (hypothermia group) or as a continuous variable (minimum NP or bladder temperature) (all P > 0.05). In patients undergoing proximal aortic surgery including arch replacement requiring HCA, degree of systemic hypothermia was not associated with the risk of AKI. These data suggest that moderate hypothermia does not confer increased risk of AKI for patients requiring circulatory arrest, although additional prospective data are needed.

A Study of Brittle Crack Arrestability Test Method

This study evaluated the brittle crack arrest temperature (CAT) through an isothermal crack arrest test. The concept of evaluating CAT by an isothermal crack arrest test was proposed by C. Wiesner for application to low temperature steels for LPG tanks. The proposed test method consists of arresting a double-tension-type brittle crack with EB melt-run, which acts as a crack initiator and crack runway. There are some disadvantages when evaluating CAT with electron beam welding (EBW), which requires a local brittle zone to initiate a brittle crack. A local temperature gradient (LTG) system is developed to overcome the limitations of the EBW method. LTG systems do not require additional EBW to develop a brittle zone to initiate brittle crack. Recently, brittle crack arrest (BCA) steels are being used in large container ship such as in the upper deck or hatch side coaming of 22,000 twenty-foot equivalent units to prevent fatal brittle fracture accident of those ships. The International Association of Classification Societies (IACS) defined BCA steels using Kca requirement or CAT requirement in their unified rule (UR) S33. Therefore, when a shipyard uses BCA steel in the construction of large container ships, CAT or Kca should be evaluated. In this study, a new CAT test method is introduced to evaluate brittle crack arrest temperature more easily. Furthermore, both test methods were compared for the same specimens to verify the validity of the test method. Key words: Brittle fracture, Crack Arrest Temperature (CAT), Electron Beam Welding (EBW), Embrittled zone, Local Temperature Gradient (LTG)