Degree Of Hypothermia Research Articles

Risk factors and outcome of aortic surgery patients with hypothermic circulatory arrest: can urine NGAL predict acute kidney injury?

Hypothermic circulatory arrest (HCA) is useful to protect visceral organs during aortic operations. The degree of hypothermia and the influence of renal damage remain controversial. To evaluate the incidence of acute kidney injury (AKI) comparing moderate HCA (MHCA) and deep HCA (DHCA) and determine risk factors and ability of urine neutrophil gelatinase associated lipocalin (u-NGAL) to predict AKI. We prospectively enrolled 58 patients who underwent aortic replacement with HCA during May 2019-August 2021. Patients were divided into 2 groups: DHCA (15-20°C) and MHCA (20-25°C). The primary outcome was incidence of AKI. Secondary outcomes included risk factors of AKI. Baseline characteristics were not different between the 2 groups. There were 37 patients in the DHCA group and 21 patients in the MHCA group. Each group was mostly diagnosed with acute type A aortic dissection (60.3%). The operation was hemiarch replacement (51.7%). The overall incidence of AKI was 65.6% according to KDIGO criteria; there was no statistically significant difference between DHCA and MHCA groups. Urine NGAL level at cut-off point > 20 ng/ml at hour 0 and > 70 ng/ml at hour 6 could predict AKI. Operation time more than 360 minutes was found to be a risk factor for AKI. In hospital mortality rates and neurological outcomes were not statistically significantly different between DHCA and MHCA groups. AKI is common in patients undergoing HCA with an overall incidence of more than 60%. Risk factors of AKI after aortic surgery include long operative time. U-NGAL in the early post-operative period can predict AKI.

Abstract 316: Reperfusion With Mild versus Moderate Hypothermia in a Swine Model of Extracorporeal Cardiopulmonary Resuscitation

Background: Targeted temperature management (TTM) at lower temperatures has shown variable neuroprotective benefits in clinical trials of cardiac arrest. We hypothesized that moderate hypothermia at the time of VA-ECMO reperfusion followed by early rewarming would reduce brain injury in a swine model of refractory VF, compared to mild hypothermia. Methods: Fourteen female pigs had electrically induced VF and conventional CPR for 30 minutes. Animals were cannulated to VA-ECMO and randomized to TTM to 34°C for 4 hours (mild hypothermia, n=7) or 24°C for 1 hour followed by early rewarming to 34°C over 3 hours (moderate hypothermia, n=7). Cooling was initiated upon ECMO reperfusion by circulating ice water through the oxygenator. Brain temperature and cerebral and systemic hemodynamics were continuously monitored. After four hours of post-arrest and ECMO care, brain tissue was obtained for examination. Groups were compared using paired t- and Wilcoxon rank sum tests. Results: The mean time to target brain temperature was 5 and 35 minutes in the mild and moderate groups, respectively (Panel, A). CPR hemodynamics were similar. Carotid blood flow (CBF) was higher in moderate hypothermia animals (79.0±1.56 vs 60.7±1.86% pre-arrest baseline, P <0.001) throughout the post-arrest period. There were no differences in ECMO flow, mean arterial pressure, vasopressor/fluid requirement, bleeding, or thromboelastography. No significant difference in histologic damage score was observed between groups (10.5 [7, 11.8] vs 13 [9, 20], with 24°C vs 34°C respectively P =0.25; Panel, B). Immunohistochemistry markers for white matter and neuronal injury also did not significantly diverge. Conclusion: In a swine model of refractory cardiac arrest treated with ECPR, moderate hypothermia initiated upon reperfusion followed by early rewarming did not appear to be neuroprotective. Histological brain injury at 4 hours post-resuscitation was not affected by the degree of hypothermia.

Analysis of rebound intracranial pressure occurring during rewarming after therapeutic hypothermia in traumatic brain injury patients

ObjectiveTo investigate the risk factors associated with rebound intracranial pressure (ICP), a phenomenon that occurs when brain swelling reprogresses rapidly during rewarming in patients who have undergone therapeutic hypothermia for traumatic brain injury (TBI). MethodsThis study analyzed 42 patients who underwent therapeutic hypothermia among 172 patients with severe TBI admitted to a single regional trauma center between January 2017 and December 2020. Forty-two patients were classified into 34.5 °C (mild) and 33 °C (moderate) hypothermia groups according to the therapeutic hypothermia protocol for TBI. Rewarming was initiated post-hypothermia, wherein ICP was maintained at ≤ 20 mmHg and cerebral perfusion pressure was maintained at ≥ 50 mmHg for ≥ 24 h. In the rewarming protocol, the target core temperature was increased to 36.5 °C at 0.1 °C/h. ResultsOf the 42 patients who underwent therapeutic hypothermia, 27 did not survive: 9 in the mild and 18 in the moderate hypothermia groups. The moderate hypothermia group had a significantly higher mortality rate than the mild hypothermia group (p = 0.013). Rebound ICP occurred in 9 of 25 patients: 2 in the mild and 7 in the moderate hypothermia groups. In the risk factor analysis of rebound ICP, only the degree of hypothermia was statistically significant, and rebound ICP was observed more frequently in the moderate than in the mild hypothermia group (p = 0.025). ConclusionsIn patients who underwent rewarming after therapeutic hypothermia, rebound ICP presented a higher risk at 33 °C than at 34.5 °C. Therefore, more careful rewarming is needed in patients receiving therapeutic hypothermia at 33 °C.

Acute Kidney Injury With a Miniaturized Extracorporeal Circuit for Neonatal Cardiopulmonary Bypass

The objectives of this study were to evaluate the incidence and to identify risk factors for acute kidney injury (AKI) in neonates undergoing cardiopulmonary bypass (CPB) with a miniaturized bloodless primed extracorporeal circuit. A retrospective cohort study. A single-center, tertiary academic hospital. Data of 462 patients were analyzed. With a retrospective analysis of neonates undergoing CPB with bloodless priming between May 2007 and August 2019, the incidence of AKI was determined according to the neonatal Kidney Disease: Improving Global Outcomes classification. Multivariate logistic regression analyses were performed to determine risk factors for AKI. The incidence of AKI was 41.1% (190 of 462); 30.3% (n=140) had mild stage 1, 6.5% (n=30) reached stage 2, and 4.3% (n=20) reached stage 3. Multivariate logistic regression showed that degree of hypothermia (p=0.05), duration of CPB (p=0.03), and lower baseline serum creatinine (p < 0.001) were associated independently with AKI. In the authors' patient population, patients without transfusion of donor-derived erythrocytes had a lower incidence of AKI (p=0.003). AKI stages 2 and 3 were associated with longer duration of mechanical ventilation (p=0.008) and increased length of stay in the intensive care unit (p=0.03). With a miniaturized CPB circuit and bloodless priming, the AKI incidence was well within the range consistent with previously reported studies from other institutions.

Non-heparin-induced thrombocytopenia in patients after open-heart surgery.

Thrombocytopenia (platelet count below 150 x 103/μL) is a common finding after open-heart surgery and can lead to various complications, including patient death. This study aimed to determine the extent of non-heparin-induced thrombocytopenia in open-heart surgery and to highlight the associated factors. In this cohort study, 842 patients who underwent valve and/or coronary bypass surgery over a 5-year period were retrospectively analyzed. After open-heart surgery, patients whose platelet count was less than 150 x 103/μL on a complete blood count 12 and 24h after surgery were classified as thrombocytopenic. Three hundred twenty patients without thrombocytopenia and 21 patients with a high probability of heparin-induced thrombocytopenia were excluded from the study. Logistic regression analysis was used to assess the association of independent variables in moderate-severe thrombocytopenia: Age groups, sex, underlying disease, symptoms, type of surgery, pump time, pulsatile or non-pulsatile duration, degree of hypothermia, hemodilution, oxygenator type, use of an intra-aortic balloon, and erythrocyte transfusion counts were included in the analysis. A total of 501 patients were diagnosed as having non-heparin-induced thrombocytopenia, and 64.3% were male. Three hundred seventy-seven (75.2%) patients had mild thrombocytopenia and 124 (24.7%) had moderate-severe thrombocytopenia. The postoperative platelet count was significantly lower than the preoperative platelet count (213 x 103 vs.117 x 103/μL; p < 0.001). Moderate-severe thrombocytopenia was associated with age ≥80years odds (OR = 9.026, 95% CI: [1.757-46.363]; p = 0.008), isolated valve surgery (OR = 3.090, 95% CI: [1.867-5.114]; p < 0.001), and valve surgery with coronary bypass (OR = 4.938, 95% CI: [1.638-14.889]; p = 0.005) compared to isolated coronary bypass, type of oxygenator (Nipro vital compared with Affinity OR = 11.097, 95% CI: [1.923-64.023]; p = 0.007), erythrocyte transfusion count (OR = 1.219, 95%CI: [1.046-1.420]; p = 0.011). Age 80years or older, surgical procedures including heart-valve surgery, and the number of red blood cell transfusions are associated with the risk of moderate-to-severe thrombocytopenia. This study provides a guide in terms of risk factors that may lead to moderate-to-severe thrombocytopenia after open-heart surgery. However, future multicentre prospective randomized studies may provide more detailed information on this subject.

Effect of low dose phenylephrine infusion on shivering and hypothermia in patients undergoing cesarean section under spinal anesthesia: a randomized clinical trial

BackgroundShivering is a common complication of spinal anesthesia. Phenylephrine, due to its peripheral vasoconstrictive effect, may limit the core to periphery redistribution of body temperature following spinal anesthesia, and reduce hypothermia and shivering. We hypothesized that prophylactic phenylephrine infusion would reduce shivering and hypothermia in women undergoing cesarean section under spinal anesthesia. MethodsA two-arm randomized, double-blind, placebo-controlled trial in term pregnant patients undergoing cesarean section. In the phenylephrine group (n=75) prophylactic phenylephrine infusion was administered at 25 µg/min immediately after initiation of spinal anesthesia and continued until the end of the operative period. In the placebo group (n=75) a normal saline infusion was administered during the same period. The primary outcome was the incidence of shivering; secondary outcomes were severity of shivering, changes in nasopharyngeal (core) temperature, and incidence of hypotension and bradycardia. ResultsThe incidence of shivering in the phenylephrine and control groups was 24.0% (95% CI 14.3% to 33.7%) and 53.3% (95% CI 42.0% to 64.6%), respectively. The severity of shivering was greater in the control group (P=0.002) and the mean (±SD) end of surgery core temperature was significantly higher in the phenylephrine group (35.84°C ± 0.60) compared with controls (35.61°C ± 0.48) (P=0.009). The incidence of hypotension was higher in controls (53.4% vs. 2.7%; P <0.001) but bradycardia more frequent in group P (P=0.023). ConclusionThe incidence of shivering and degree of hypothermia were significantly reduced by a prophylactic phenylephrine infusion during cesarean section under spinal anesthesia.

Значение волны Осборна в выборе своевременной тактики лечения пациентов с гипотермией на примере клинического случая

Гипотермия ассоциируется с рядом электрокардиографических изменений, которые варьируют в зависимости от степени гипотермии. В данной статье мы рассматриваем факторы риска развития гипотермии, клиническое значение волны Осборна, механизмы ее возникновения, критерии выявления волны Осборна на электрокардиограмме, а также представляем клинический случай, когда даже незначительная гипотермия в сочетании с неврологической патологией индуцирует появление волны Осборна. Также рассматривается прогностическое значение волны Осборна в возникновении желудочковых аритмий.

Factors associated with acute kidney injury and mortality during cardiac surgery.

Cardiac surgery with cardiopulmonary bypass (CPB) is known to contribute towards the incidence of acute kidney injury (AKI) and peri-operative morbidity and mortality. There are several patient, anaesthetic and surgical factors that contribute to its occurrence. It is imperative to know the profile of a patient who is likely to develop this complication to mitigate for modifiable risks. This study aimed at describing a profile of AKI in an adult patient (over the age of 18 years) following cardiac surgery on CPB. Factors associated with the development of cardiac surgery-associated acute kidney injury (CSA-AKI) are described, as well as the relationship between CSA-AKI and in-hospital mortality. This was a contextual, descriptive and retrospective single-centre study with data of 476 adult patients admitted post cardiac surgery between January 2016 and December 2017. Data were collected from Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) in South Africa. All adult patients who presented for elective cardiac surgery (coronary artery bypass graft), valvular, aortic and other cardiac surgery on CPB were included. Peri-operative factors such as patient demographics, baseline renal function, co-morbid factors, length of CPB and aortic cross-clamp time, degree of hypothermia, use of assist devices, and post-operative serum creatinine (SCr) levels were collected. Incomplete essential peri-operative data and data for patients who presented on renal replacement therapy (RRT) already were excluded. AKI was defined by Kidney Disease Improving Global Outcomes (KDIGO) criteria. One hundred and thirty-five (28%) patients developed CSA-AKI and 20, 5 and 3% were in KDIGO 1, 2 and 3, respectively. Older age (p = 0.024), female gender (p = 0.015), higher serum creatinine level (p = 0.025), and lower estimated glomerular filtration rate (eGFR) (p = 0.025) were associated with the development of CSA-AKI, while a history of hypertension was predictive. Forty-six of the 476 patients died. Mortality rates were significantly higher in those with AKI compared to those without [28 (21%) vs 18 (5%), respectively (p = 0.001)]. The incidence was significantly worse in those with severe kidney injury, as evidenced by mortality rates of 44 versus 5% between KDIGO 3 and KDIGO 1 (p < 0.001). Pre-operative eGFR and CSA-AKI requiring RRT were significantly associated with mortality, while pre-operative eGFR was an independent predictor of mortality (hazard ratio 0.99, 95% confidence interval: 0.97-0.99, p = 0.019). A history of hypertension was predictive of the development of CSA-AKI, and pre-operative eGFR was an independent predictor of mortality in this cohort. Both factors are modifiable.

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.

Risk Factors Associated with Acute Kidney Injury in Neonates and Infants Following Open Heart Surgery

BACKGROUND: The complexity of surgical cardiac procedures is on the rise, resulting in prolonged cardiopulmonary bypass time and stay in the intensive care unit. One major complication of cardiac surgery is acute kidney injury. The aim of this study is to investigate the incidence and risk factors associated with acute kidney injury following open heart surgery. METHODOLOGY: This is a retrospective cohort study that involved chart review of patients &lt;1 year old who underwent open heart surgery from January 2012 to December 2017 in a tertiary cardiovascular referral center. Preoperative characteristics included age, gender, weight, cardiac diagnosis, baseline serum creatinine, history of mechanical ventilation and cardiac catheterization and pre operative medications given. Intra-operative characteristics included cardiopulmonary bypass and cross clamp time of cardiac surgery, and degree of hypothermia . Post operatively, urine output, systolic blood pressure, mean arterial pressure, highest serum creatinine and blood urea nitrogen were recorded. RESULTS: Sixty one (61) patients were included in the study. Nine patients (15%) developed post-operative acute kidney injury, two of which underwent peritoneal dialysis. Lowest systolic blood pressure and lowest mean arterial pressure were noted to be significant in the development of acute kidney injury with odds ratio of 0.95 (p=0.049) and 0.93 (p=0.025), respectively. The duration of mechanical ventilation was also significantly increased in patients who developed acute kidney injury (p=0.028). CONCLUSION: Lowest systolic blood pressure and lowest mean arterial pressure are significant risk factors for acute kidney injury in neonates and infants following open heart surgery. KEYWORDS: acute kidney injury, acute renal failure, cardiac surgery in infants, congenital heart disease, cardiopulmonary bypass time

Condition of microcirculatory and hemostasis systems in rats after moderate hypothermia

Hypothermia produces a generalized impact on an organism, with involvement of all organs and systems into the response. It was shown that hypothermia promotes multi-organ dysfunction syndrome, which makes it important to study the influence of hypothermia on condition of hemostasis and microcirculatory systems.&#x0D; Aim. To study the condition of the hemostasis system and the microcirculatory bed in different periods of moderate hypothermia in rats.&#x0D; Materials and Methods. The current study was performed on 50 male Wistar rats. Condition of microcirculatory blood stream in all animals was assessed with laser Doppler flowmetry. Condition of hemostasis system was studied according to routine protocols and an integrated method of examination – thromboelastography. Statistical analysis was performed using Statistica 6.0 software package (StatSoft, USA) with calculation of Mann-Whitney nonparametric test.&#x0D; Results. Analysis of the experimental data showed that moderate hypothermia produced a pronounced modulating influence on the microcirculatory system. Vasodilatation occurred immediately after reaching the stage of hypothermia, suggesting the beginning of decompensation in the experimental animals. The highest risk for hemodynamic pathologies was observed 5 days after cessation of cooling and was characterized by a massive reduction in the vascular tone, intensification of hemodynamics against the background appearance of thrombinemia markers in the blood stream and pronounced inhibition of fibrinolysis. Enhanced hemodynamics of the nutritional vascular bed with the underlying progressive prothrombotic condition is a potent risk factor for thrombosis and multiple organ dysfunction syndrome. Vasospasm that developed 2 weeks after recovery of the body temperature, indicated a profound modulation of vasculature and preservation of high-level sympathetic input, as well as increasing rigidity of blood vessel walls. Rising fibrinogen concentrations confirm a progressive inflammatory reaction.&#x0D; Conclusion. A moderate degree of hypothermia produces a pronounced modulating effect on the microcirculation. The established regularities make it possible to form a clear understanding of the course and development of the pathological reaction in the body of victims and to give recommendations on the use of pharmacological medicine for preventive therapy. Thus, a period has been established when thrombotic readiness is maximal, and use of anticoagulant and antiplatelet drugs is required, together with drugs that improve rheological properties of blood.

Factors associated with acute stroke after type A aortic dissection repair: An analysis of the Society of Thoracic Surgeons National Adult Cardiac Surgery Database

ObjectivesData from the Society of Thoracic Surgeons Adult Cardiac Surgery Database was used to examine the incidence and factors associated with acute stroke following type A repair. MethodsAcute type A aortic dissection repairs performed from 2014 to 2017 were identified from the Society of Thoracic Surgeons Adult Cardiac Surgery Database. The effect of cannulation strategy (eg, axillary, femoral, direct, or innominate), lowest temperature, cerebral protection techniques (antegrade cerebral profusion, retrograde cerebral perfusion, both, or none), repair technique, and institutional volume on postoperative stroke was investigated. ResultsAcute type A repair was performed on 8937 patients at 772 centers, of which 7353 met inclusion criteria. Operative mortality was 17% and incidence of postoperative stroke was 13%. Axillary cannulation was associated with lower risk of stroke versus femoral (odds ratio, 0.60; P < .001). Retrograde cerebral perfusion was associated with reduced risk for stroke compared with no cerebral perfusion (odds ratio, 0.75; P = .008) or antegrade cerebral perfusion (odds ratio, 0.75; P = .007). Total arch replacement was associated with greater risk for stroke versus hemiarch technique (odds ratio, 1.30; P = .013). Longer circulatory arrest time, cerebral perfusion time, and cardiopulmonary bypass time were all related to higher risk of postoperative stroke. ConclusionsStroke is a common complication after type A repair. Axillary cannulation was associated with lower incidence of stroke, whereas femoral cannulation significantly increased the risk of stroke regardless of the cerebral perfusion strategy or the degree of hypothermia. Retrograde cerebral profusion was found to have reduced risk for postoperative stroke. Degree of hypothermia and center volume were not related to stroke incidence.

Postoperative hypothermia in geriatric patients undergoing arthroscopic shoulder surgery

Background: Hypothermia below 36°C is a common problem during arthroscopic shoulder surgery. Geriatric patients are more vulnerable to perioperative hypothermia. The present study compared postoperative hypothermia between geriatric and young adult patients receiving arthroscopic shoulder surgery. Methods: Data were collected retrospectively from a geriatric group (aged 65 or more, n = 29), and a control group (aged 19-64, n = 33) using the anesthesia records of patients who had undergone arthroscopic shoulder surgery. The primary outcome measure was the incidence of hypothermia upon arrival in the postanesthesia care unit (PACU). The secondary outcome measure was the decrease in body temperature from admission into the operating room to admission into the PACU. Results: The incidence of hypothermia was 93.1% and 54.5% in the geriatric and control groups, respectively, demonstrating a significant difference between the groups (P < 0.001). Comparison between body temperature revealed a decrease of 1.5 ± 0.6°C and 1.0 ± 0.4°C in the geriatric and control groups, respectively, showing a significant difference between the groups (P < 0.001). The degree of hypothermia was significantly different between the groups (P = 0.027). No shivering was observed in either of the two groups, but the incidence of thermal discomfort was higher in the geriatric group than in the control group (P = 0.021). Conclusions: In geriatric patients undergoing arthroscopic shoulder surgery, both the incidence of postoperative hypothermia and the associated temperature drop are more prominent than those in young adult patients. Additional warming methods will be needed to prevent postoperative hypothermia in geriatric patients. Keywords: Aged; Arthroscopy; Hypothermia

Clinical characteristics of elderly drowning patients

PurposeDrowning is one of the major causes of traumatic death. The impact of drowning in the elderly and patients who were not elderly will be different because of physiological differences. We wanted to analyze the clinical differences such as mortality, incidence rate of complications, degree of hypothermia and rate of cardiac arrest between elderly and adult drowning patients. MethodsThis study included drowning patients over 18 years old who came to an emergency department (ED) located on a riverside from September 1997 to July 2016. Patients over the age of 65 years were classified as elderly, while those under the age of 65 years were classified as adults. Demographic data and clinical outcomes were surveyed. ResultsA total of 611 patients were included in this study. Sixty-one patients (9.9%) were elderly, and 550 patients (90.1%) were adults. There were 17 elderly patients (15.8%) and 87 adult patients (27.9%) who had cardiac arrest at the time of ED arrival (p = 0.017). The rate of body temperatures < 34 °C was higher in elderly patients than that in adult patients (27.9% vs 17.5%, respectively, p = 0.025). The rates of hospitalization in the intensive care unit (ICU) and mortality were higher in elderly group (23% vs. 15.1%, respectively, p = 0.01; 37.7% vs 21.8%, respectively, p = 0.01). There was no significant difference in suicidal intent between the elderly and adult patient groups (82.0% vs 78.9%, respectively, p = 0.421). ConclusionsElderly drowning patients accounted for approximately 1/10 of all drowning cases and were more likely to experience a cardiac arrest, hypothermia, mortality, and ICU admission.

Intraoperative care for aortic surgery using circulatory arrest.

The total circulatory arrest (CA) is necessary to achieve optimal surgical conditions in certain aortic pathologies, especially in those affecting the ascending aorta and aortic arch. During this procedure it is necessary to protect all the organs of ischemia, especially those of the central nervous system and for this purpose several strategies have been developed. The first and most important protective method is systemic hypothermia. The degree of hypothermia and the route of application have been evolving and currently tend to use moderate hypothermia (MH) (20.1-28 °C) associated with unilateral or bilateral selective cerebral perfusion methods. In this way the neurological results are better, the interval of security is greater and the times of extracorporeal circulation are smaller. Even so, it is necessary to take into account that there is the possibility of ischemia in the lower part of the body, especially of the abdominal viscera and the spinal cord, therefore the time of circulatory stop should be limited and not to exceed 80 minutes. Evidence of possible neurological drug protection is very weak and only mannitol, magnesium, and statins can produce some benefit. Inhalational anesthetics and some intravenous seem to have advantages, but more studies would be needed to test their long-term benefit. Other important parameters to be monitored during these procedures are blood glucose, anemia and coagulation disorders and acid-base balance. The recommended monitoring is common in complex cardiovascular procedures and it is of special importance the neurological monitoring that can be performed with several techniques, although currently the most used are Bispectral Index (BIS) and Near-Infrared Spectroscopy (NIRS). It is also essential to monitor the temperature routinely at the nasopharyngeal and bladder level and it is important to control coagulation with rotational thromboelastometry (ROTEM).

Corrigendum to: "Glial fibrillary acidic protein plasma levels are correlated with degree of hypothermia during cardiopulmonary bypass in congenital heart disease surgery" [Interact CardioVasc Thorac Surg 2017

Corrigendum to: "Glial fibrillary acidic protein plasma levels are correlated with degree of hypothermia during cardiopulmonary bypass in congenital heart disease surgery" [Interact CardioVasc Thorac Surg 2017

Optimal temperature management in aortic arch operations.

Hypothermic circulatory arrest is a critical component of aortic arch procedures, without which these operations could not be safely performed. Despite the use of hypothermia as a protective adjunct for organ preservation, aortic arch surgery remains complex and is associated with numerous complications despite years of surgical advancement. Deep hypothermic circulatory arrest affords the surgeon a safe period of time to perform the arch reconstruction, but this interruption of perfusion comes at a high clinical cost: stroke, paraplegia, and organ dysfunction are all potential-associated complications. Retrograde cerebral perfusion was subsequently developed as a technique to improve upon the rates of neurologic dysfunction, but was done with only modest success. Selective antegrade cerebral perfusion, on the other hand, has consistently been shown to be an effective form of cerebral protection over deep hypothermia alone, even during extended periods of circulatory arrest. A primary disadvantage of using deep hypothermic circulatory arrest is the prolonged bypass times required for cooling and rewarming which adds significantly to the morbidity associated with these procedures, especially coagulopathic bleeding and organ dysfunction. In an effort to mitigate this problem, the degree of hypothermia at the time of the initial circulatory arrest has more recently been reduced in multiple centers across the globe. This technique of moderate hypothermic circulatory arrest in combination with adjunctive brain perfusion techniques has been shown to be safe when performing aortic arch operations. In this review, we will discuss the evolution of these protection strategies as well as their relative strengths and weaknesses.

Thermal Blanket to Improve Thermoregulation in Preterm Infants: A Randomized Controlled Trial.

To determine the effectiveness of temperature-controlled thermal blanket as additional thermoprotection. Randomized controlled prospective study. Single-center tertiary neonatal unit. Inborn very low-birth-weight (< 1,500 g) infants. Infants were prospectively assigned to thermal blanket group or control at 1:1 ratio. Additional to radiant warmers, a prewarmed blanket of Blanketrol II (Cincinnati Sub-Zero Products, Cincinnati, OH) was applied as mattress for thermal blanket group. The outcomes included temperature and blood pressure changes. We defined hypothermia as temperature less than 36°C and hypotension as mean arterial pressure less than index infant's gestational age in weeks. Total 80 very low-birth-weight infants were allocated, and there was no between-group demographic dissimilarity. At 30th minute, fewer infants in thermal blanket group were hypothermic (43% vs 68%; p = 0.025). These infants had significantly lower prevalence of hypotension, which associated with less dopamine use in the first 6 hours of life (25% vs 50%; p = 0.016). There was no hyperthermia more than 37.5°C episode. By using thermal blanket to provide additional thermal protection for very low-birth-weight infants, the degree of hypothermia was improved, which related to fewer hypotensive cases and less dopamine usage.

Evaluation of Positive Inotropic Drug Effects on Thyroid Hormone Levels after Open Heart Surgery

The aim of this study was to examine the effects of positive inotropic drugs, including adrenaline, dopamine, and dobutamine on thyroid hormone levels following open heart surgery. We analyzed free thyroid hormones (FT3 and FT4) and thyroid-stimulating hormones (TSH) in 200 consecutive patients undergoing open heart surgery. Patients were divided into 5 groups according to the inotropic drug administration as follows: Group A (n = 46) received dopamine alone; Group B (n = 40), dopamine and dobutamine; Group C (n = 36), dopamine, dobutamine, and adrenaline; Group D (n = 32), adrenaline alone; and Group E (n = 46), placebo. Procedural factors affecting thyroid hormones were recorded and included cardiopulmonary bypass (CPB) time, cross-clamping time, degree of hypothermia, and the duration and doses of positive inotropic drugs. Blood samples for hormone assays were collected before initiation of inotropic drug therapy (baseline) and postoperatively at 24, 72, and 120 hours after drug therapy. FT3, FT4, and TSH levels at baseline were similar in all groups. Although there was a trend showing very slight increases in thyroid hormone levels from baseline to the 24th, 72nd, and 120th postoperative hours after drug therapy, these changes were not significant, and there were also no significant differences between the groups. There was also no significant statistical difference in CPB time, cross-clamping time, degree of hypothermia, and duration and doses of positive inotropic drugs between groups. Although thyroid hormone levels were affected by positive inotropic drug usage after open heart surgery, this effect was not significant and thyroid hormone levels remained within normal ranges.

Hypothermia--mechanism of action and pathophysiological changes in the human body

This review focuses on the physiological responses and pathophysiological changes induced by hypothermia. Normal body function depends on its ability to maintain thermal homeostasis. The human body can be divided arbitrarily into two thermal compartments: a core compartment (trunk and head), with precisely regulated temperature around 37°C, and a peripheral compartment (skin and extremities) with less strictly controlled temperature, and lower than the core temperature. Thermoregulatory processes occur in three phases: afferent thermal sensing, central regulation, mainly by the preoptic area of the anterior hypothalamus, and efferent response. Exposure to cold induces thermoregulatory responses including cutaneous vasoconstriction, shivering and non-shivering thermogenesis, and behavioral changes. Alterations of body temperature associated with impaired thermoregulation, decreased heat production or increased heat loss can lead to hypothermia. Hypothermia is defined as a core body temperature below 35ºC, and may be classified according to the origin as accidental (e.g. caused by exposure to a cold environment, drugs, or illness) or intentional (i.e. therapeutic), or by the degree of hypothermia as mild, moderate or severe. Classification by temperature is not universal. Lowering of body temperature disrupts the physiological processes at the molecular, cellular and system level, but hypothermia induced prior to cardiosurgical or neurosurgical procedures, by the decrease in tissue oxygen demand, can reduce the risk of cerebral or cardiac ischemic damage. Therapeutic hypothermia has been recommended as a clinical procedure in situations characterized by ischemia, such as cardiac arrest, stroke and brain injuries.