Pathophysiologic changes and effects of hypothermia on outcome in elective surgery and trauma patients

Enhancing Liver Transplant Outcomes through Liver Precooling to Mitigate Inflammatory Response and Protect Mitochondrial Function

Transplanted organs experience several episodes of ischemia and ischemia-reperfusion. The graft injury resulting from ischemia-reperfusion (IRI) remains a significant obstacle to the successful survival of transplanted grafts. Temperature significantly influences cellular metabolic rates because biochemical reactions are highly sensitive to temperature changes. Consequently, lowering the temperature could reduce the degradative reactions triggered by ischemia. In mitigating IRI in liver grafts, the potential protective effect of localized hypothermia on the liver prior to blood flow obstruction has yet to be explored. In this study, we applied local hypothermia to mouse donor livers for a specific duration before stopping blood flow to liver lobes, a procedure called "liver precooling". Mouse donor liver temperature in control groups was controlled at 37 °C. Subsequently, the liver donors were preserved in cold University of Wisconsin solution for various durations followed by orthotopic liver transplantation. Liver graft injury, function and inflammation were assessed at 1 and 2 days post-transplantation. Liver precooling exhibited a significant improvement in graft function, revealing more than a 47% decrease in plasma aspartate transaminase (AST) and alanine aminotransferase (ALT) levels, coupled with a remarkable reduction of approximately 50% in liver graft histological damage compared to the control group. The protective effects of liver precooling were associated with the preservation of mitochondrial function, a substantial reduction in hepatocyte cell death, and a significantly attenuated inflammatory response. Taken together, reducing the cellular metabolism and enzymatic activity to a minimum level before ischemia protects against IRI during transplantation.

Does Scheduled Low-Dose Short-Term NSAID (Ketorolac) Modulate Cytokine Levels After Orthopaedic Polytrauma? A Secondary Analysis of a Randomized Clinical Trial

OBJECTIVES

To determine whether scheduled low-dose, short-term ketorolac modulates cytokine concentrations in orthopaedic polytrauma patients.

METHODS

DESIGN

Secondary analysis of a double-blinded, randomized controlled trial.

SETTING

Single Level I trauma center from August 2018 to October 2022.

PATIENT SELECTION CRITERIA

Orthopaedic polytrauma patients between 18 and 75 years with a New Injury Severity Score greater than 9 were enrolled. Participants were randomized to receive 15 mg of intravenous ketorolac every 6 hours for up to 5 inpatient days or 2 mL of intravenous saline similarly.

OUTCOME MEASURES AND COMPARISONS

Daily concentrations of prostaglandin E2 and interleukin (IL)-1a, IL-1b, IL-6, and IL-10. Clinical outcomes included hospital and intensive care unit length of stay, pulmonary complications, and acute kidney injury.

RESULTS

Seventy orthopaedic polytrauma patients were enrolled, with 35 participants randomized to the ketorolac group and 35 to the placebo group. The overall IL-10 trend over time was significantly different in the ketorolac group ( P = 0.043). IL-6 was 65.8% higher at enrollment compared to day 3 ( P < 0.001) when aggregated over both groups. There was no significant treatment effect for prostaglandin E2, IL-1a, or IL-1b ( P > 0.05). There were no significant differences in clinical outcomes between groups ( P > 0.05).

CONCLUSIONS

Scheduled low-dose, short-term, intravenous ketorolac was associated with significantly different mean trends in IL-10 concentration in orthopaedic polytrauma patients with no significant differences in prostaglandin E2, IL-1a, IL-1b, or IL-6 levels between groups. The treatment did not have an impact on clinical outcomes of hospital or intensive care unit length of stay, pulmonary complications, or acute kidney injury.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Core temperature following pre-hospital induction of anaesthesia in trauma patients

INTRODUCTION

Hypothermia is a well-recognised finding in trauma patients, which can occur even in warmer climates. It is an independent predictor of increased morbidity and mortality. It is associated with pre-hospital intubation, although the reasons for this are likely to be multifactorial. Core temperature drop after induction of anaesthesia is a well-known phenomenon in the context of elective surgery, and the mechanisms of this are well established.

METHODS

We conducted a prospective observational study to examine the behaviour of core temperature in patients undergoing pre-hospital anaesthesia for traumatic injuries.

RESULTS

Between 2017 and 2021 data were collected on 48 patients. The data from 40 of these were included in the final analysis.

DISCUSSION

Our data do not show a decrease in the core temperatures of patients who receive pre-hospital anaesthesia, unlike patients who are anaesthetised without pre-warming, in operating theatres. The lack of a change could relate to patient, anaesthetic or environmental factors.

Temperature Monitoring and Thermal Support in Exotic Animal Critical Care

Body temperature measurement is one of the most important parameters to assess the health of a patient. In small exotic mammals, rectal temperature is obtained via a similar process as in dogs or cats, with a few specific differences. In reptiles and birds, measurement of body temperature can provide important information, albeit its accuracy may be limited. In most animals, temperature should be taken at the beginning of the examination to not artificially elevate the temperature during the physical exam. Heat support is typically indicated any time a patient's temperature is below the accepted core temperature range and cooling may be indicated whenever a patient's temperature exceeds a critical point.

Pathophysiology in patients with polytrauma

The pathophysiology after polytrauma represents a complex network of interactions. While it was thought for a long time that the direct and indirect effects of hypoperfusion are most relevant due to the endothelial permeability changes, it was discovered that the innate immune response to trauma is equally important in modifying the organ response. Recent multi center studies provided a "genetic storm" theory, according to which certain neutrophil changes are activated at the time of injury. However, a second hit phenomenon can be induced by activation of certain molecules by direct organ injury, or pathogens (damage associated molecular patterns, DAMPS - pathogen associated molecular patterns, PAMPS). The interactions between the four pathogenetic cycles (of shock, coagulopathy, temperature loss and soft tissue injuries) and cross-talk between coagulation and inflammation have also been identified as important modifiers of the clinical status. In a similar fashion, overzealous surgeries and their associated soft tissue injury and blood loss can induce secondary worsening of the patient condition. Therefore, staged surgeries in certain indications represent an important alternative, to allow for performing a "safe definitive surgery" strategy for major fractures. The current review summarizes all these situations in a detailed fashion.

The Effect of Extreme Cold on Complete Blood Count and Biochemical Indicators: A Case Study

Regular exposure to a cold factor-cold water swimming or ice swimming and cold air-results in an increased tolerance to cold due to numerous adaptive mechanisms in humans. Due to the lack of scientific reports on the effects of extremely low outdoor temperatures on the functioning of the human circulatory system, the aim of this study was to evaluate complete blood count and biochemical blood indices in multiple Guinness world record holder Valerjan Romanovski, who was exposed to extremely cold environment from -5 °C to -37 °C for 50 days in Rovaniemi (a city in northern Finland). Valerjan Romanovski proved that humans can function in extremely cold temperatures. Blood from the subject was collected before and after the expedition. The subject was found to have abnormalities for the following blood indices: testosterone increases by 60.14%, RBC decreases by 4.01%, HGB decreases by 3.47%, WBC decreases by 21.53%, neutrocytes decrease by 17.31%, PDW increases by 5.31%, AspAT increases by 52.81%, AlAT increase by 68.75%, CK increases by 8.61%, total cholesterol decreases by 5.88%, HDL increases by 28.18%. Percentage changes in other complete blood count and biochemical indices were within standard limits. Long-term exposure of the subject (50 days) to extreme cold stress had no noticeable negative effect on daily functioning.

Rectal temperature is a prognostic indicator in client-owned guinea pigs

OBJECTIVES

To determine whether rectal temperature was associated with patient mortality in client-owned guinea pigs upon presentation to a veterinary hospital.

MATERIALS AND METHODS

The medical record database at a veterinary teaching hospital was searched for records of guinea pigs from January 2016 through June 2019. Guinea pigs were included in the study if a rectal temperature was measured at presentation and there was data on survival status 7 days post-presentation. If survivor status was not documented in the medical record, follow-up information was obtained from the client via telephone or email. The data was ultimately collected from 201 client-owned guinea pigs who presented for 388 independent examinations. Univariable, multivariable and sensitivity analyses were performed.

RESULTS

Guinea pigs with hypothermia (<37.9°C) at presentation had a relative risk of mortality within 7 days of presentation almost 3 times greater than guinea pigs without hypothermia (relative risk: 2.88; 95% confidence interval: 1.86 to 4.48). For each 0.55°C decrease in rectal temperature, the odds of death increased 1.6 times (odds ratio: 1.64; 95% confidence interval: 1.42 to 2.89). Sensitivity analyses confirmed the robustness of the finding.

CLINICAL SIGNIFICANCE

Rectal temperature was a predictor of death for guinea pigs presenting for care at a veterinary hospital. Obtaining a rectal temperature recording should be considered for patient guinea pigs.

Association of hypothermia with increased mortality rate in SARS-CoV-2 infection

OBJECTIVE

Patients were observed to have variable temperatures. The objective of this study was to identify whether hypothermia in a patient infected with SARS-CoV-2 was associated with a higher than expected mortality.

METHODS

In total, 331 charts from patients hospitalized with SARS-CoV-2 between March 9 and April 20, 2020 were reviewed.

RESULTS

The probability of death was 2.06 times higher for those with hypothermia than for those without (95% CI 1.25-3.38)]. In ventilated patients, there were 32 deaths. Of these, 75% had been hypothermic. In a prior review of 10 000 non-SARS-CoV-2 patients with sepsis, the mortality rate in patients with hypothermia was 47%. A review of previous studies demonstrated a range of expected mortality rates in patients with ventilator-dependent respiratory failure and sepsis. In comparison, our study showed that within a group of critically ill patients with SARS-CoV-2 and hypothermia, the mortality rate exceeded those rates.

CONCLUSION

Our review showed a significant association between hypothermia and death (p = 0.0033). Predictors of mortality in SARS-CoV-2 disease can expedite earlier aggressive care. Additionally, in areas with limited resources or overburdened healthcare systems, where there may be a need for resource allocation management, information about mortality risk may be helpful.

Numerical investigations of temperature and hemodynamics in carotid arteries with and without atherosclerotic plaque during open surgery

Intraoperative monitoring is essential for providing safe and effective care during open surgery. In this paper, numerical simulation is performed to track the flow and heat transfer of carotid arteries with and without atherosclerotic plaque in a real physiological system during surgery, in which the heat transport is first considered to couple to the blood flow due to the temperature dependence of the blood viscosity. The impacts of the operating room temperature and hematocrit (H) on the viscosity, velocity, temperature, wall shear stress (WSS), pressure drop and oscillation are investigated. The results demonstrate that the presence of plaque in the carotid artery induces a greater blood flow velocity, pressure drop, WSS, and oscillation, as well as a smaller viscosity and temperature variations. A decreasing ambient temperature leads to a decrease in the temperature and an increase in the low-WSS area, which implies a greater risk of hypothermia and atherosclerosis. As H increases, the high-WSS areas substantially expand; when H varies from 65% to 80%, WSS_ave increases by 70.02% and 68.57% for the arteries with and without plaque, respectively, which indicates a higher risk of vascular injury. The results obtained can serve as a guideline regarding the selection of an operating room temperature for carotid disease patients with distinct hematocrits.

Pre-warming before general anesthesia with isoflurane delays the onset of hypothermia in rats

General anesthesia causes hypothermia by impairing normal thermoregulatory mechanisms. When using inhalational anesthetic agents, Redistribution of warm blood from the core to the periphery is the primary mechanism in the development of hypothermia and begins following induction of anesthesia. Raising skin temperature before anesthesia reduces the temperature gradient between core and periphery, decreasing the transfer of heat. This prospective, crossover study (n = 17 adult male and female SD rats) compared three treatment groups: PW1% (pre-warming to increase core temperature 1% over baseline), PW40 (pre-warming to increase core temperature to 40°C) and NW (no warming). The PW1% group was completed first to ensure tolerance of pre-warming. Treatment order was then randomized and alternated after a washout period. Once target temperature was achieved, anesthesia was induced and maintained with isoflurane in oxygen without further external temperature support. Pre-warming was effective at delaying the onset of hypothermia, with a significant difference between PW1% (12.4 minutes) and PW40 (19.3 minutes, p = 0.0044 (95%CI -12 to -2.2), PW40 and NW (7.1 minutes, p < 0.0001 (95%CI 8.1 to 16.0) and PW1% and NW (p = 0.003, 95%CI 1.8 to 8.7). The rate of heat loss in the pre-warmed groups exceed that of the NW group: PW1% versus NW (p = 0.005, 95%CI 0.004 to 0.027), PW40 versus NW (p < 0.0001, 95%CI 0.014 to 0.036) and PW1% versus PW40 (p = 0.07, 95%CI -0.021 to 0.00066). Pre-warming alone confers a protective effect against hypothermia during volatile anesthesia; however, longer duration procedures would require additional heating support.

Impact of Accidental Hypothermia on Pulmonary Complications in Multiply Injured Patients With Blunt Chest Trauma - A Matched-pair Analysis

BACKGROUND/AIM

Blunt chest trauma is one of the major injuries in multiply injured patients and is associated with an increased risk of acute respiratory distress syndrome (ARDS) and ventilator-associated pneumonia (VAP). Accidental hypothermia is a common accompaniment of multiply injured patients. The objective of this study was to analyze the influence of accidental hypothermia on pulmonary complications in multiply injured patients with blunt chest trauma.

PATIENTS AND METHODS

Multiply injured patients [injury severity score (ISS) ≥16] with severe blunt chest trauma [abbreviated injury scale of the chest (AISchest) ≥3] were analyzed. Hypothermia was defined as body core temperature <35°C. The primary endpoint was the development of ARDS and VAP. Propensity score matching was performed.

RESULTS

Data were analyzed for 238 patients, with a median ISS of 26 (interquartile range=12). A total of 67 patients (28%) were hypothermic on admission. Hypothermic patients were injured more severely (median ISS 34 vs. 24, p<0.001) and had a higher transfusion requirement (p<0.001). Their mortality rate was consequently increased (10% vs. 1%, p=0.002); After propensity score matching, the mortality rate was still higher (10% vs. 2%, p=0.046). However, hypothermia was not an independent predictor of mortality. Hypothermic patients had to be ventilated longer (p=0.02). However, there were no differences in occurrence of ARDS and VAP. Hypothermia was not identified as an independent predictor of ARDS and VAP.

CONCLUSION

Among multiply injured patients with severe blunt chest trauma, accidental hypothermia is not an independent predictor of ARDS and VAP and is more likely to be an accompaniment of injury severity and hemorrhage.

Impact of Donor Core Body Temperature on Graft Survival After Heart Transplantation

BACKGROUND

A previous donor intervention trial found that induction of mild therapeutic hypothermia in the brain-dead donor reduced the dialysis requirement after kidney transplantation. Consequences on the performance of cardiac allografts after transplantation were not explored to date.

METHODS

Cohort study investigating 3-year heart allograft survival according to spontaneous core body temperature (CBT) assessed on the day of organ procurement. The study is nested in the database of the randomized trial of donor pretreatment with low-dose dopamine (ClinicalTrials.gov identifier: NCT000115115).

RESULTS

Ninety-nine heart transplant recipients who had received a cardiac allograft from a multiorgan donor enrolled in the dopamine trial were grouped by tertiles of the donor's CBT assessed by a mere temperature reading 4 to 20 hours before procurement (lowest, 32.0-36.2°C; middle, 36.3-36.8°C; highest, 36.9-38.8°C). Baseline characteristics considering demographics of donors and recipients, concomitant donor treatments, donor hemodynamic, and respiratory parameters as well as underlying cardiac diseases in recipients, pretransplant hemodynamic assessments, including pretransplant inotropic/mechanical support, urgency, and waiting time were similar. A lower CBT was associated with inferior heart allograft survival (hazard ratio, 0.53; 95% confidence interval, 0.31-0.93, per tertile; P = 0.02, and hazard ratio, 0.68; 95% confidence interval, 0.50-0.93°C; P = 0.02) when CBT was included as continuous explanatory variable in the Cox regression analysis.

CONCLUSIONS

A lower CBT in the brain-dead donor before procurement may associate with an unfavorable clinical course after heart transplantation. More research is required, before therapeutic hypothermia can routinely be used in multiorgan donors when a cardiac transplantation is intended.

The influence of body mass index on temperature management during general anaesthesia-A prospective observational study

RATIONALE, AIMS, AND OBJECTIVES

During general anaesthesia, body core temperature is influenced by several factors that are either anaesthesia-related (type and duration of anaesthesia and fluid management), surgery-related (type of surgery and extent of the surgical procedure), or patient-related (age, gender, body weight, and preoperative body core temperature). Interestingly, data concerning body mass index (BMI) and its influence on patients' temperature are sparse. The aim of this study was to evaluate the impact of BMI on body core temperature under general anaesthesia.

METHODS

A single centre, prospective, observational study was conducted at a university hospital. Two cohorts (lower limb surgery and abdominal surgery) were evaluated. Patients were treated according to actual German guidelines for the prevention of hypothermia. Temperature was measured sublingually prior to anaesthesia and during the first 60 minutes of anaesthesia. Each cohort was divided in three subgroups (BMI < 24 kg m^-2 , BMI 25-34.9 kg m^-2 , and BMI > 35 kg m^-2 ) according to body weight.

RESULTS

A total of 206 patients were evaluated. One hundred four underwent lower limb surgery; 102 underwent abdominal surgery. After induction of anaesthesia, temperature dropped in all subgroups, but this decline was more pronounced in patients with lower BMI. Significant differences concerning temperature changes were observed in abdominal surgery between low and high BMI groups. After 60 minutes of anaesthesia, group-dependent temperature differences had levelled out, and relevant differences compared with preoperative temperatures could no longer be observed in any of the groups.

CONCLUSION

Current guidelines provide effective protection against perioperative hypothermia. In the current study, this was true for obese as well as normal weight patients.

Incidence and strategies for preventing sustained hypothermia of crash victims during prolonged vehicle extrication

BACKGROUND

Vehicle extrication of crash victims is a highly-demanding challenge, due to the frequently life-threatening injuries of entrapped occupants. In this phase, crash victims are often exposed to the outdoor-temperature, with the risk of sustained hypothermia. Hypothermia can significantly raise the morbidity and mortality rates of crash victims. Therefore, we have correlated the incidence of severe car accidents with entrapped patients, the outdoor conditions, and expenditure of time for extrication. Furthermore, different warming strategies have been evaluated regarding their integrability within the rescue procedure.

METHODS

To estimate the incidence of severe car accidents with entrapped patients, we performed retrospective data mining for the cold season of a three-year period in a rural district in Germany. We evaluated the integrability of a chemical heated blanket, its combined application with a forced-air warmer, or with an infrared radiator for patient warming. Therefore, we analysed the time tracking of extrication reference points during extrication exercises undertaken by the rescue services, simulating a severe vehicle accident and evaluated questionnaires administered to rescue personnel and subjects. Furthermore, we monitored subjects' physiologic parameters to estimate the warming effect.

RESULTS

Incidence analysis resulted in extrication times of up to 80 min, representing two severely-entrapped patients per month in the cold seasons, corresponding to about four entrapments per 100.000 inhabitants every year. Of the different warming strategies analysed, the chemical blanket and the combination infrared radiator/chemical blanket were favoured regarding the items 'operator convenience', 'weight/size/handling', 'stability in positioning', 'time needed for installation', 'manpower requirement', 'hindrance during extrication operation', 'versality during extrication process', and 'robustness' by the rescue personnel; the forced-air warmer and the infrared radiator were preferred with regard to 'warming effect', the forced-air warmer and the chemical blanket was advantageous with regard to 'physical protection'.

CONCLUSIONS

Vehicle extrication procedures are time consuming, a relevant finding that provides a rationale for discussing and optimising the rescue procedure to prevent sustained hypothermia. We determined that combined application of an infrared radiator and a chemical blanket is advantageous in terms of integration into the rescue process. However, a more detailed investigation, focussing on warming efficacy, must be performed.

Hypothermia in trauma patients arriving at an emergency department by ambulance in Johannesburg, South Africa: a prospective study

Introduction

Normal body temperature is considered to be between 36 and 38°C. Temperatures that are too low may negatively affect physiological functions. In trauma cases, factors that promote the development of hypothermia include concomitant hypoxia, hypotension, decreased levels of consciousness, contact with cold surfaces, exposure to low ambient temperatures and the administration of cold fluids. Studies on emergency department related hypothermia in Africa are sparse. This study investigated instances of hypothermia in a sample of trauma cases arriving by ambulance to an emergency department in Johannesburg, South Africa.

Methods

Core body temperatures of 140 trauma cases were measured upon arrival and 30 minutes later. Ambient temperatures outside the hospital, inside the ED and in the resuscitation areas were also recorded. Additional information was gathered describing the equipment available to the ambulance crews for temperature, control and rewarming.

Results

Seventy-two (51%) of the cases were found to have core body temperatures less than 36°C upon arrival. Twenty-nine (21%) the cases were considered clinically hypothermic (core temperatures of less than <35°C). After 30 minutes, 79 (56%) of the participants had core body temperatures of less than 36°C and 39 (28%) remained lower than 35°C. Patients were not warming up in the ED as expected. Rather, some had become colder. The study also found that the ambient temperature in the triage area fluctuated and was recorded as less than the recommended 21°C in 95 (68%) of the cases. In addition, the majority of ambulances that transported these cases lacked appropriate equipment on board to properly facilitate temperature control and rewarming.

Conclusion

Fifty-one percent of the trauma cases arriving by ambulance had core temperature <36°C. Many became even colder in the ED. Attention needs to be given to the early identification of hypothermia, the regulation of ambient temperatures inside the ED including the provision of appropriate heating and rewarming devices on ambulances.

Hypothermia does not influence liver damage and function in a porcine polytrauma model

BACKGROUND

Previous studies revealed evidence that induced hypothermia attenuates ischemic organ injuries after severe trauma. In the present study, the effect of hypothermia on liver damage was investigated in a porcine long term model of multi-system injury, consisting of blunt chest trauma, penetrating abdominal trauma, musculoskeletal injury, and hemorrhagic shockMETHODS: In 30 pigs, a standardized polytrauma including blunt chest trauma, penetrating abdominal trauma, musculoskeletal injury, and hemorrhagic shock of 45% of total blood volume was induced. Following trauma, hypothermia of 33∘C was induced for 12 h and intensive care treatment was evaluated for 48 h. As outcome parameters, we assessed liver function and serum transaminase levels as well as a histopathological analysis of tissue samples. A further 10 animals served as controls.

RESULTS

Serum transaminase levels were increased at the end of the observation period following hypothermia without reaching statistical significance compared to normothermic groups. Liver function was preserved (p⩽ 0.05) after the rewarming period in hypothermic animals but showed no difference at the end of the observation period. In H&E staining, cell death was slightly increased hypothermic animals and caspase-3 staining displayed tendency towards more apoptosis in hypothermic group as well.

CONCLUSIONS

Induction of hypothermia could not significantly improve hepatic damage during the first 48 h following major trauma. Further studies focusing on multi-organ failure including a longer observation period are required to illuminate the impact of hypothermia on hepatic function in multiple trauma patients.

Effect of hypothermia on apoptosis in traumatic brain injury and hemorrhagic shock model

INTRODUCTION

The neuroprotective mechanisms of therapeutic hypothermia against trauma-related injury have not been fully understood yet. In this study, we aimed to investigate the effects of therapeutic hypothermia on biochemical and histopathological markers of apoptosis using Traumatic brain injury (TBI) and hemorrhagic shock (HS) model.

METHODS

A total of 50 male albino-wistar rats were divided into five groups: Group isolated TBI, Group NT (HT+HS+normothermia), Group MH (HT+HS+mild hypothermia), Group MoH (HT+HS+moderate hypothermia) and Group C (control). Neurological deficit scores were assessed at baseline and at 24h. The rats were, then, sacrificed to collect serum and brain tissue samples. Levels of Caspase-3,6,8, proteoglycan-4 (PG-4), malondialdehyde (MDA), and nitric oxide (NO) were measured in serum and brain tissue samples. Histopathological examination was performed in brain tissue.

RESULTS

There were significant differences in the serum levels of Caspase-3 between Group NT and Group C (p=0.018). The serum levels of Caspase-6 in Group NT (0.70±0.58) were lower than Group MH (1.39±0.28), although the difference was not statistically significant (p=0.068). There were significant differences in the brain tissue samples for Caspase-3 levels between Group NT and Group C (p=0.049). A significant difference in the Caspase-8 brain tissue levels was also observed between Group NT and Group C (p=0.022). Group NT had significantly higher scores of all the pathological variables (for edema p<0.017; for gliosis p<0.001; for congestion p<0.003, for hemorrhage p<0.011) than Group C.

CONCLUSION

Our study results suggest that hypothermia may exert its neuroprotective effects by reducing markers of apoptotic pathway, particularly Caspase-3 on TBI and HS.

Therapeutic Whole-body Hypothermia Protects Remote Lung, Liver, and Kidney Injuries after Blast Limb Trauma in Rats

BACKGROUND

Severe blast limb trauma (BLT) induces distant multiple-organ injuries. In the current study, the authors determined whether whole-body hypothermia (WH) and its optimal duration (if any) afford protection to the local limb damage and distant lung, liver, and kidney injuries after BLT in rats.

METHODS

Rats with BLT, created by using chartaceous electricity detonators, were randomly treated with WH for 30 min, 60 min, 3 h, and 6 h (n = 12/group). Rectal temperature and arterial blood pressure were monitored throughout. Blood and lung, liver, and kidney tissue samples were harvested for measuring tumor necrosis factor-α, interleukin-6 and interleukin-10, myeloperoxidase activity, hydrogen sulfide, and biomarkers of oxidative stress at 6 h after BLT. The pathologic lung injury and the water content of the lungs, liver, and kidneys and blast limb tissue were assessed.

RESULTS

Unlike WH for 30 min, WH for 60 min reduced lung water content, lung myeloperoxidase activity, and kidney myeloperoxidase activity by 10, 39, and 28% (all P < 0.05), respectively. WH for 3 h attenuated distant vital organs and local traumatic limb damage and reduced myeloperoxidase activity, hydrogen peroxide and malondialdehyde concentration, and tumor necrosis factor-α and interleukin-6 levels by up to 49% (all P < 0.01). Likewise, WH for 6 h also provided protection to such injured organs but increased blood loss from traumatic limb.

CONCLUSIONS

Results of this study indicated that WH may provide protection for distant organs and local traumatic limb after blast trauma, which warrants further study.

The impact of mild induced hypothermia on the rate of transfusion and the mortality in severely injured patients: a retrospective multi-centre study

BACKGROUND

Although under discussion, induced hypothermia (IH) is an established therapy for patients with cardiac arrest or traumatic brain injuries. The influences on coagulopathy and bleeding tendency in severely injured patients (SIP) with concomitant traumatic brain injury are most widely unclear. Therefore, the aim of this study was to quantify the effect of mild IH in SIP with concomitant severe traumatic brain injuries on transfusion rate and mortality.

METHODS

In this retrospective multi-centre study, SIP from three European level-1 trauma centres with an ISS ≥16 between 2009 and 2011 were included. At hospital A, patients qualified for IH with age ≤70 years and a severe head injury with an abbreviated injury scale (AIS_Head) of ≥3. IH was defined as target core body temperature of 35 °C. Hypothermic patients were matched with two patients, one from hospital B and one from hospital C using age and AIS_Head. The effect of IH on the transfusion rate, complications and mortality was quantified with 95 % confidence intervals (CI). Patients not treated with IH in hospital A and those from hospital B and C, who were not matched, were used to adjust the CI for the effect of inter-hospital therapy protocol differences.

RESULTS

Mean age of patients in the IH-group (n = 43) was 35.7 years, mean ISS 30 points and sex distribution showed 83.7 % male. Mean age of matched patients in the normotherm-group (n = 86) was 36.7 years, mean ISS 33 points and there were 75.6 % males. For the hypothermic patients, we pointed out an estimate of mean difference for the number of transfused units of packed red blood cells as well as for mortality which does not indicate a decrease in the benefit gained by hypothermia. It is suggested that hypothermic patients tend to a higher rate of lung failure and thromboembolisms.

CONCLUSION

Though tending to an increased rate of complications, there is no evidence for a difference in both; rate of transfusion and mortality in SIP. Mild IH as an option for severe head injuries seems as well-being practicable in the presence of multiple severe injuries. Further, clinical studies regarding the side effects are necessary.

Hypothermia and near-drowning associated with life-threatening injuries: A remarkable recovery: A case report

A young male suffered multiple severe injuries after a fall and near-drowning. On presentation to the emergency department (ED), he was in a critical and unstable condition and his chances of survival were deemed very low. This case illustrates the management of the hypothermic multi-trauma patient and the remarkable recovery made possible by a high standard of care.

Hypothermia as a predictor for mortality in trauma patients at admittance to the Intensive Care Unit

Aims:

To study the impact of hypothermia upon admission to the Intensive Care Unit (ICU) on early and late mortality and to develop a prediction model for late mortality in severely injured trauma patients.

Materials and Methods:

A multicenter retrospective cohort study was performed in adult trauma patients admitted to the ICU of two Level-1 trauma centers between 2007 and 2012. Hypothermia was defined as a core body temperature of ≤35° Celsius. Logistic regression analyses were performed to quantify the effect of hypothermia on 24-hour and 28-day mortality and to develop a prediction model.

Results:

A total of 953 patients were included, of which 354 patients had hypothermia (37%) upon ICU admission. Patients were divided into a normothermic or hypothermic group. Hypothermia was associated with a significantly increased mortality at 24 hours and 28 days (OR 2.72 (1.18-6.29 and OR 2.82 (1.83-4.35) resp.). The variables included in the final prediction model were hypothermia, age, APACHE II score (corrected for temperature), INR, platelet count, traumatic brain injury and Injury Severity Score. The final prediction model discriminated between survivors and non-survivors with high accuracy (AUC = 0.871, 95% CI 0.844-0.898).

Conclusions:

Hypothermia, defined as a temperature ≤35° Celsius, is common in critically ill trauma patients and is one of the most important physiological predictors for early and late mortality in trauma patients. Trauma patients admitted to the ICU may be at high risk for late mortality if the patient is hypothermic, coagulopathic, severely injured and has traumatic brain injury or an advanced age.

Accidental hypothermia in severe trauma

Hypothermia, along with acidosis and coagulopathy, is part of the lethal triad that worsen the prognosis of severe trauma patients. While accidental hypothermia is easy to identify by a simple measurement, it is no less pernicious if it is not detected or treated in the initial phase of patient care. It is a multifactorial process and is a factor of mortality in severe trauma cases. The consequences of hypothermia are many: it modifies myocardial contractions and may induce arrhythmias; it contributes to trauma-induced coagulopathy; from an immunological point of view, it diminishes inflammatory response and increases the chance of pneumonia in the patient; it inhibits the elimination of anaesthetic drugs and can complicate the calculation of dosing requirements; and it leads to an over-estimation of coagulation factor activities. This review will detail the pathophysiological consequences of hypothermia, as well as the most recent principle recommendations in dealing with it.

Long-Term Effects of Induced Hypothermia on Local and Systemic Inflammation - Results from a Porcine Long-Term Trauma Model

Background

Hypothermia has been discussed as playing a role in improving the early phase of systemic inflammation. However, information on the impact of hypothermia on the local inflammatory response is sparse. We therefore investigated the kinetics of local and systemic inflammation in the late posttraumatic phase after induction of hypothermia in an established porcine long-term model of combined trauma.

Materials & Methods

Male pigs (35 ± 5kg) were mechanically ventilated and monitored over the study period of 48 h. Combined trauma included tibia fracture, lung contusion, liver laceration and pressure-controlled hemorrhagic shock (MAP < 30 ± 5 mmHg for 90 min). After resuscitation, hypothermia (33°C) was induced for a period of 12 h (HT-T group) with subsequent re-warming over a period of 10 h. The NT-T group was kept normothermic. Systemic and local (fracture hematoma) cytokine levels (IL-6, -8, -10) and alarmins (HMGB1, HSP70) were measured via ELISA.

Results

Severe signs of shock as well as systemic and local increases of pro-inflammatory mediators were observed in both trauma groups. In general the local increase of pro- and anti-inflammatory mediator levels was significantly higher and prolonged compared to systemic concentrations. Induction of hypothermia resulted in a significantly prolonged elevation of both systemic and local HMGB1 levels at 48 h compared to the NT-T group. Correspondingly, local IL-6 levels demonstrated a significantly prolonged increase in the HT-T group at 48 h.

Conclusion

A prolonged inflammatory response might reduce the well-described protective effects on organ and immune function observed in the early phase after hypothermia induction. Furthermore, local immune response also seems to be affected. Future studies should aim to investigate the use of therapeutic hypothermia at different degrees and duration of application.

Therapeutic hypothermia applicable to cardiac surgery

OBJECTIVE

To review the beneficial and adverse effects of therapeutic hypothermia (TH) applicable to cardiac surgery with cardiopulmonary bypass (CPB) in the contexts of various temperature levels and techniques for achieving TH.

DATABASES USED

Multiple electronic literature searches were performed using PubMed and Google for articles published from June 2012 to December 2014. Relevant terms (e.g. 'hypothermia', 'cardiopulmonary bypass', 'cardiac surgery', 'neuroprotection') were used to search for original articles, letters and reviews without species limitation. Reviews were included despite potential publication bias. References from the studies identified were also searched to find other potentially relevant citations. Abstracts, case reports, conference presentations, editorials and expert opinions were excluded.

CONCLUSIONS

Therapeutic hypothermia is an essential measure of neuroprotection during cardiac surgery that may be achieved most effectively by intravascular cooling using hypothermic CPB. For most cardiac surgical procedures, mild to modest (32-36 °C) TH will be sufficient to assure neuroprotection and will avoid most of the adverse effects of hypothermia that occur at lower body core temperatures.

Induced Hypothermia Does Not Harm Hemodynamics after Polytrauma: A Porcine Model

BACKGROUND

The deterioration of hemodynamics instantly endangers the patients' life after polytrauma. As accidental hypothermia frequently occurs in polytrauma, therapeutic hypothermia still displays an ambivalent role as the impact on the cardiopulmonary function is not yet fully understood.

METHODS

We have previously established a porcine polytrauma model including blunt chest trauma, penetrating abdominal trauma, and hemorrhagic shock. Therapeutic hypothermia (34°C) was induced for 3 hours. We documented cardiovascular parameters and basic respiratory parameters. Pigs were euthanized after 15.5 hours.

RESULTS

Our polytrauma porcine model displayed sufficient trauma impact. Resuscitation showed adequate restoration of hemodynamics. Induced hypothermia had neither harmful nor major positive effects on the animals' hemodynamics. Though heart rate significantly decreased and mixed venous oxygen saturation significantly increased during therapeutic hypothermia. Mean arterial blood pressure, central venous pressure, pulmonary arterial pressure, and wedge pressure showed no significant differences comparing normothermic trauma and hypothermic trauma pigs during hypothermia.

CONCLUSIONS

Induced hypothermia after polytrauma is feasible. No major harmful effects on hemodynamics were observed. Therapeutic hypothermia revealed hints for tissue protective impact. But the chosen length for therapeutic hypothermia was too short. Nevertheless, therapeutic hypothermia might be a useful tool for intensive care after polytrauma. Future studies should extend therapeutic hypothermia.

Trauma resuscitation and monitoring: military lessons learned

Over the past 13 years, the military health care system has made improvements that are associated with an unprecedented survival rate for severely injured casualties. Monitoring for indications of deterioration as the critically injured patient moves across the continuum of care is difficult given the limitations of routinely used vital signs. Research by both military and civilian researchers is revolutionizing monitoring, with an increased focus on noninvasive, continuous, dynamic measurements to provide earlier, more sensitive indications of the patient's perfusion status.

Perioperative prostate specific antigen levels among coronary artery bypass grafting patients: Does extracorporeal circulation and body temperature induce prostate specific antigen levels alterations?

Purpose:

The purpose of this study is to compare the perioperative total prostate specific antigen (tPSA) levels among coronary artery bypass grafting (CABG) patients with and without extracorporeal circulation (ECC), to investigate the changes overtime of tPSA in each group separately and to determine the effect of body core temperature on tPSA levels.

Materials and Methods:

A prospective study was conducted. Our sample was allocated to: (a) Seven patients who underwent off pump CABG (Group I) and (b) 16 CABG patients with ECC (Group II). The levels of tPSA were measured preoperatively (baseline), intra-operatively and at the 4^th postoperative day. We compared the two groups on their tPSA levels and we investigated the changes of tPSA overtime in each group separately.

Results:

Intra-operative serum samples were obtained in significantly lower body temperature in patients of Group II than in those of Group I (31°C vs. 36.9°C, P < 0.001). In each group separately, postoperative tPSA levels were increased significantly compared to the baseline values (2.55 ng/ml vs. 0.39 ng/ml for Group I, P = 0.005 and 4.36 ng/ml vs. 0.77 for Group II, P < 0.001). CABG patients with ECC had significantly lower intra-operative tPSA levels than the baseline values (0.67 ng/ml vs. 0.77 ng/ml, P = 0.008). We did not observe significant differences of tPSA levels between the two groups.

Conclusions:

CABG surgery affects similarly the perioperative tPSA independently the involvement of ECC. Although all patients had significantly higher early postoperative tPSA levels, only those who underwent CABG with ECC had exceeded normal values and significantly decreased intra-operative tPSA. Hypothermia seems to be the causal factor of tPSA reduction.

Effects of hypothermia on the liver in a swine model of cardiopulmonary resuscitation

BACKGROUND

The study aimed to explore the effects of hypothermia state induced by 4 ºC normal saline (NS) on liver biochemistry, enzymology and morphology after restoration of spontaneous circulation (ROSC) by cardiopulmonary resuscitation (CPR) in swine.

METHODS

After 4 minutes of ventricular fibrillation (VF), standard CPR was carried out. Then the survivors were divided into two groups: low temperature group and normal temperature group. The low temperature (LT) group (n=5) received continuously 4 ºC NS at the speed of 1.33 mL/kg per minute for 22 minutes, then at the speed lowering to 10 mL/kg per hour. The normal temperature (NT) group (n=5) received NS with normal room temperature at the same speed of the LT group. Hemodynamic status and oxygen metabolism were monitored and the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were measured in blood samples obtained at baseline and at 10 minutes, 2 hours and 4 hours after ROSC. At 24 hours after ROSC, the animals were killed and the liver was removed to determine the Na(+)-K(+)-ATPase and Ca(2+)-ATPase enzyme activities and histological changes under a light or electron microscope.

RESULTS

Core temperature was decreased in the LT group (P<0.05), while HR, MAP and CPP were not significantly decreased (P>0.05) compared with the NT group (P>0.05). The oxygen extraction ratio was lower in the LT group than in the NT group (P<0.05). The serum levels of ALT, AST and LDH increased in both groups but not significantly in the LT group. The enzyme activity of liver ATP was much higher in the LT group (Na(+)-K(+)-ATP enzyme: 8.64±3.32 U vs. 3.28±0.71 U; Ca(2+)-ATP enzyme: 10.92±2.12 U vs. 2.75±0.78 U, P<0.05). The LT group showed less cellular edema, inflammation and few damaged mitochondria as compared with the NT group.

CONCLUSION

These data suggested that infusing 4 ºC NS continuously after ROSC could quickly lower the core body temperature, while maintaining a stable hemodynamic state and balancing oxygen metabolism, which protect the liver in terms of biochemistry, enzymology and histology after CPR.

Induced hypothermia reduces the hepatic inflammatory response in a swine multiple trauma model

BACKGROUND

Mild therapeutic hypothermia following trauma has been introduced in several studies to reduce the posttraumatic inflammation and organ injury. In this study, we analyzed the effects of induced mild hypothermia (34°C) on the inflammation of the shock organs liver and kidney.

METHODS

In a porcine model of multiple trauma including blunt chest trauma, liver laceration, and hemorrhagic shock followed by fluid resuscitation, the influence of induced hypothermia on hepatic and renal damage and organ-specific inflammation were evaluated. A total of 40 pigs were randomly assigned to four groups, which were sham (anesthesia only) or trauma groups receiving either hypothermia or normothermia. The parameters analyzed were laboratory parameters (aspartate transaminase [AST], lactate dehydrogenase, urea, creatinine) as well as hepatic and renal cytokine expression determined by real-time polymerase chain reaction (interleukin 6 [IL-6], IL-8). Blinded analysis of histologic changes in the liver and kidney was performed.

RESULTS

Fifteen and a half hours following combined trauma, hepatic cytokine expression and liver damage were significantly increased in animals with normothermia compared with the respective sham group. Hypothermia, however, resulted in a fivefold reduced hepatic expression of IL-8 (mean ± SE, 2.4 ± 1.3; p = 0.01) when compared with the normothermic trauma group (IL-8, 12.8 ± 4.7). Accordingly, granulocyte infiltration and a histologic, semiquantitative score for liver injury were significantly higher in the normothermic trauma group. Serum AST levels raised significantly after trauma and normothermia compared with the respective sham group, while AST levels showed no difference from the sham groups in the hypothermic trauma group. In contrast, neither trauma nor hypothermia influenced the expression of IL-6 and IL-8 and tissue injury in the kidney.

CONCLUSION

Therapeutic hypothermia seems to attenuate the hepatic inflammatory response and the associated liver injury after severe trauma. Therefore, induced hypothermia might represent a potential therapeutic strategy to avoid posttraumatic organ dysfunction.

The effects of local and general hypothermia on temperature profiles of the central nervous system following spinal cord injury in rats

Local and general hypothermia are used to treat spinal cord injury (SCI), as well as other neurological traumas. While hypothermia is known to provide significant therapeutic benefits due to its neuroprotective nature, it is unclear how the treatment may affect healthy tissues or whether it may cause undesired temperature changes in areas of the body that are not the targets of treatment. We performed 2-hour moderate general hypothermia (32°C core) or local hypothermia (30°C spinal cord) on rats that had received either a moderate contusive SCI or laminectomy (control) while monitoring temperatures at three sites: the core, spinal cord, and cortex. First, we identified that injured rats that received general hypothermia exhibited larger temperature drops at the spinal cord (-3.65°C, 95% confidence intervals [CIs] -3.72, -3.58) and cortex (-3.64°C, CIs -3.73, -3.55) than uninjured rats (spinal cord: -3.17°C, CIs -3.24, -3.10; cortex: -3.26°C, CIs -3.34, -3.17). This was found due to elevated baseline temperatures in the injured group, which could be due to inflammation. Second, both general hypothermia and local hypothermia caused a significant reduction in the cortical temperature (-3.64°C and -1.18°C, respectively), although local hypothermia caused a significantly lower drop in cortical temperature than general hypothermia (p<0.001). Lastly, the rates of rewarming of the cord were not significantly different among the methods or injury groups that were tested; the mean rate of rewarming was 0.13±0.1°C/min. In conclusion, local hypothermia may be more suitable for longer durations of hypothermia treatment for SCI to reduce temperature changes in healthy tissues, including the cortex.

Relevance of induced and accidental hypothermia after trauma-haemorrhage-what do we know from experimental models in pigs?

Recent experimental research has either focused on the role of accidental hypothermia as part of the lethal triad after trauma or tried to elucidate the effects of therapeutically induced hypothermia on the posttraumatic course. Induced hypothermia seems to reduce the mortality in experimental models of trauma-haemorrhage. As potential mechanisms, a decrease of cellular metabolism, beneficial effects on haemodynamic function and an attenuation of the inflammatory response have been described. However, negative side effects of hypothermia have to be considered, such as impairment of the coagulatory function and immunosuppressive effects. Furthermore, the optimal strategy for the induction of hypothermia (magnitude, duration, timing, cooling rate, etc.) and subsequent rewarming remains unclear. Nevertheless, this piece of information is essential before considering hypothermia as a treatment strategy for severely injured patients. This review aims to elaborate the differences between accidental and induced hypothermia and to summarize the current knowledge of the potential therapeutic use of induced hypothermia suggested in porcine models of trauma-haemorrhage.

Clinical and translational aspects of hypothermia in major trauma patients: from pathophysiology to prevention, prognosis and potential preservation

The human body strives at maintaining homeostasis within fairly tight regulated mechanisms that control vital regulators such as core body temperature, mechanisms of metabolism and endocrine function. While a wide range of medical conditions can influence thermoregulation the most common source of temperature loss in trauma patients includes: exposure (environmental, as well as cavitary), the administration of i.v. fluids, and anaesthesia/loss of shivering mechanisms, and blood loss per se. Loss of temperature can be classified either according to the aetiology (i.e. accidental/spontaneous versus trauma/haemorrhage-induced temperature loss), or according to an unintended, accidental induction in contrast to a medically intended therapeutic hypothermia. Hypothermia occurs infrequently (prevalence<10% of all injured), but more often (30-50%) in the severely injured. Hypothermia usually come together with and may aggravate acidosis and coagulopathy (the "lethal triad of trauma"), which again may be associated with a high mortality. However, recent studies disagree in the independent predictive role of hypothermia and mortality. Prevention of hypothermia is imperative through all phases of trauma care and must be an interest among all team members. Hypothermia in the trauma setting has attracted focus in the past from a pathophysiological, preventive and prognostic perspective; yet recent focus has shifted towards the potential for using hypothermia for pre-emptive and cellular protective purposes. This paper gives a brief update on some of the clinically relevant aspects of hypothermia in the injured patient.

The influence of deep hypothermia on inflammatory status, tissue hypoxia and endocrine function of adipose tissue during cardiac surgery

Changes in endocrine function of adipose tissue during surgery, such as excessive production of proinflammatory cytokines, can significantly alter metabolic response to surgery and worsen its outcomes and prognosis of patients. Therapeutic hypothermia has been used to prevent damage connected with perioperative ischemia and hypoperfusion. The aim of our study was to explore the influence of deep hypothermia on systemic and local inflammation, adipose tissue hypoxia and adipocytokine production. We compared serum concentrations of proinflammatory markers (CRP, IL-6, IL-8, sIL-2R, sTNFRI, PCT) and mRNA expression of selected genes involved in inflammatory reactions (IL-6, TNF-α, MCP-1, MIF) and adaptation to hypoxia and oxidative stress (HIF1-α, MT3, GLUT1, IRS1, GPX1, BCL-2) in subcutaneous and visceral adipose tissue and in isolated adipocytes of patients undergoing cardiosurgical operation with hypothermic period. Deep hypothermia significantly delayed the onset of surgery-related systemic inflammatory response. The relative gene expression of the studied genes was not altered during the hypothermic period, but was significantly changed in six out of ten studied genes (IL-6, MCP-1, TNF-α, HIF1-α, GLUT1, GPX1) at the end of surgery. Our results show that deep hypothermia suppresses the development of systemic inflammatory response, delays the onset of local adipose tissue inflammation and thus may protect against excessive expression of proinflammatory and hypoxia-related factors in patients undergoing elective cardiac surgery procedure.

Induced hypothermia does not impair coagulation system in a swine multiple trauma model

BACKGROUND

Accidental hypothermia, acidosis, and coagulopathy represent the lethal triad in severely injured patients. Therapeutic hypothermia however is commonly used in transplantations, cardiac and neurosurgical surgery, or after cardiac arrest. However, the effects of therapeutic hypothermia on the coagulation system following multiple trauma need to be elucidated.

METHODS

In a porcine model of multiple trauma including blunt chest injury, liver laceration, and hemorrhagic shock followed by fluid resuscitation, the influence of therapeutic hypothermia on coagulation was evaluated. A total of 40 pigs were randomly assigned to sham (only anesthesia) or trauma groups receiving either hypothermia or normothermia. Each group consisted of 10 pigs. Analyzed parameters were cell count (red blood cells, platelets), pH, prothrombin time (PT), fibrinogen concentration, and analysis with ROTEM and Multiplate.

RESULTS

Trauma and consecutive fluid resuscitation resulted in impaired coagulation parameters (cell count, pH, PT, fibrinogen, ROTEM, and platelet function). During hypothermia, coagulation parameters measured at 37°C, such as PT, fibrinogen, thrombelastometry measurements, and platelet function, showed no significant differences between normothermic and hypothermic animals in both trauma groups. Additional analyses of thrombelastometry at 34°C during hypothermia showed significant differences for clotting time and clot formation time but not for maximum clot firmness. We were not able to detect macroscopic or petechial bleeding in both trauma groups.

CONCLUSION

Based on the results of the present study we suggest that mild hypothermia can be safely performed after stabilization following major trauma. Mild hypothermia has effects on the coagulation system but does not aggravate trauma-induced coagulopathy in our model. Before hypothermic treatment can be performed in the clinical setting, additional experiments with prolonged and deeper hypothermia to exclude detrimental effects are required.

Impact of prehospital hypothermia on transfusion requirements and outcomes

BACKGROUND

Prehospital hypothermia (PH) is known to increase mortality following traumatic injury. PH relationship with transfusion requirements has not been documented. The purpose of this investigation was to analyze the impact of PH on blood product requirements and subsequent outcomes.

METHODS

The Los Angeles County Trauma System Database was queried for all patients admitted between 2005 and 2009. Demographics, physiologic parameters, and transfusion requirements were obtained and dichotomized by admission temperatures with a core temperature of less than 36.5 °C considered hypothermic. Multivariate analysis was performed to determine factors contributing to transfusion requirements and to derive adjusted odds ratios (AORs) for mortality and rates of adult respiratory distress syndrome and pneumonia.

RESULTS

A total of 21,023 patients were analyzed in our study with 44.6% presenting with PH. Hypothermic patients required 26% more fluid resuscitation (p < 0.001) in the emergency department and 17% more total blood products (p < 0.001) than those who were admitted with a normal temperature. There was a trend toward an increase in emergency department transfusion (8%, p = 0.06). PH was independently associated with the need for a transfusion (AOR, 1.1; p = 0.047), increased mortality (AOR, 2.0; p < 0.01), as well as incidence of adult respiratory distress syndrome (AOR, 1.8; p < 0.05) and pneumonia (AOR, 2.6; p < 0.01).

CONCLUSION

PH is associated with increased transfusion and fluid requirements and subsequently worse outcomes. Interventions that correct hypothermia may decrease transfusion requirements and improve outcomes. Prospective studies investigating correction of hypothermia in trauma patients are warranted.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Hypothermia for acute spinal cord injury--a review

OBJECTIVE

Spinal cord injury (SCI) is a catastrophic neurological event with no proven treatments that protect against its consequences. Potential benefits of hypothermia in preventing/limiting central nervous system injury are now well known. There has been an interest in its potential use after SCI. This article reviews the current experimental and clinical evidence on the use of therapeutic hypothermia in patients with SCI.

METHODS

Review of literature.

RESULTS

There are various mechanisms by which hypothermia is known to protect the central nervous system. Modest hypothermia (32°C-34°C) can deliver the potential benefits of hypothermia without incurring the complications associated with deep hypothermia. Several recent experimental studies have repeatedly shown that the use of hypothermia provides the benefit of neuroprotection after SCI. Although older clinical studies were often focused on local cooling strategies and demonstrated mixed results, more recent data from systemic hypothermia use demonstrate its safety and its benefits. Endovascular cooling is a safe and reliable method of inducing hypothermia.

CONCLUSIONS

There is robust experimental and some clinical evidence that hypothermia is beneficial in acute SCI. Larger, multicenter trials should be initiated to further study the usefulness of systemic hypothermia in SCI.

Effect of hypothermia on coagulatory function and survival in Sprague-Dawley rats exposed to uncontrolled haemorrhagic shock

BACKGROUND

Acute coagulopathy, hypothermia, and acidosis are the lethal triad of conditions manifested by major trauma patients. Recent animal studies have reported that hypothermia improves survival in animals subjected to controlled haemorrhagic shock. The objective of this study was to investigate the effect of hypothermia on coagulation in rats subjected to uncontrolled haemorrhagic shock.

METHODS

Thirty-two male Sprague-Dawley rats were randomly divided into four groups: normothermia (control, group N), hypothermia (group H), hypothermic haemorrhagic shock (group HS), and normothermic haemorrhagic shock (group NS). Haemorrhagic shock was induced by splenic laceration. Capacity for coagulation was measured by rotation thromboelastometry (ROTEM(®)), and was measured at baseline as well as the end of the shock and resuscitation periods. Survival was observed for 48 h post-trauma.

RESULTS

Baseline parameters were not different amongst the groups. Rats exposed to hypothermia alone did not differ in coagulation capacity compared to the control group. Clot formation time (CFT) and maximal clot firmness (MCF) in group HS decreased as the experiment progressed. Maximal clot firmness time (MCFt) in groups H and HS was significantly prolonged during shock and resuscitation compared with that in group NS. In group NS, MCF did not change significantly, but MCFt was reduced compared with baseline. Group HS had poor survival when compared with normovolaemic groups.

CONCLUSION

Blood clotted less firmly in traumatic haemorrhagic shock, and hypothermia prolonged clotting. However, clot firmness maximised rapidly under normothermic haemorrhagic shock. Haemorrhage would continue for a longer time in hypothermic haemorrhagic shock. Survival of hypothermic shock was not significantly different compared to that of normothermic haemorrhagic shock.

Effects of accidental hypothermia on posttraumatic complications and outcome in multiple trauma patients

INTRODUCTION

Accidental hypothermia seems to predispose multiple trauma patients to the development of posttraumatic complications, such as Systemic Inflammatory Response Syndrome (SIRS), sepsis, Multiple Organ Dysfunction Syndrome (MODS), and increased mortality. However, the role of accidental hypothermia as an independent prognostic factor is controversially discussed. The aim of the present study was to evaluate the incidence of accidental hypothermia in multiple trauma patients and its effects on the development of posttraumatic complications and mortality.

PATIENTS AND METHODS

Inclusion criteria for patients in this retrospective study (2005-2009) were an Injury Severity Score (ISS) ≥16, age ≥16 years, admission to our Level I trauma centre within 6h after the accident. Accidental hypothermia was defined as body temperature less than 35°C measured within 2 h after admission, but always before first surgical procedure in the operation theatre. The association between accidental hypothermia and the development of posttraumatic complications as well as mortality was investigated. Statistical analysis was performed with χ(2)-test, Student's t-test, ANOVA and logistic regression. Statistical significance was considered at p<0.05.

RESULTS

310 multiple trauma patients were enrolled in the present study. Patients' mean age was 41.9 (SD 17.5) years, the mean injury severity score was 29.7 (SD 10.2). The overall incidence of accidental hypothermia was 36.8%. The overall incidence of posttraumatic complications was 77.4% (SIRS), 42.9% (sepsis) and 7.4% (MODS), respectively. No association was shown between accidental hypothermia and the development of posttraumatic complications. Overall, 8.7% died during the posttraumatic course. Despite an increased mortality rate in hypothermic patients, hypothermia failed to be an independent risk factor for mortality in multivariate analysis.

CONCLUSIONS

Accidental hypothermia is very common in multiply injured patients. However, it could be assumed that the increase of mortality in hypothermic patients is primarily caused by the injury severity and does not reflect an independent adverse effect of hypothermia. Furthermore, hypothermia was not shown to be an independent risk factor for posttraumatic complications.

The effects of surgery type and duration of tourniquet inflation on body temperature

OBJECTIVE

To identify factors related to the decrease in core body temperature after deflation of a pneumatic tourniquet during unilateral knee surgery under general anaesthesia.

METHODS

This observational study recruited 30 patients scheduled for arthroscopic surgery (group A) and 30 patients scheduled for open surgery (group O). Intraoperative oesophageal temperature was measured during tourniquet inflation and every minute for 10 min after deflation.

RESULTS

Core temperature decreased significantly after tourniquet deflation in both groups, the decrease being significantly greater in group A than in group O. Duration of tourniquet inflation and type of surgery were correlated with the temperature decrease.

CONCLUSIONS

In knee surgery using a tourniquet, the decrease in core body temperature after tourniquet deflation was closely related to the duration of tourniquet inflation and to arthroscopic rather than open surgery. Further studies are required to determine the effect of surgery type on temperature changes, independently of the duration of tourniquet inflation.

Hypothermia for prediction of death in severely injured blunt trauma patients

Hypothermia is considered an independent predictor of death after trauma. The aim of this study was to assess these premises based on data from the TraumaRegistry DGU® (TR-DGU) using its outcome predication tool, the Revised Injury Severity Classification (RISC) score, in comparison with three previously published regression models by Shafi, Martin, and Wang. We hypothesized that body temperature on admission would improve accuracy of the RISC score. Data of 5,197 patients with documented body temperature on admission (T) and complete data for RISC score prognosis were selected from TR-DGU. Hypothermia was defined as T of 35°C or less. Patients were divided into hypothermia and normothermia group. Differences were assessed using Mann-Whitney U and chi-squared tests. Statistical significance was accepted at P < 0.01(*). Moreover, we performed multivariate logistic regression analyses using TR-DGU data on the four models (including RISC) with hospital mortality as dependant variable. Results are given as mean or odds ratio (OR) with 95% confidence intervals (95% CIs). Hypothermic patients were more severely injured (Injury Severity Score, 35.0 vs. 29.2 points*) and had higher rates of shock (38.3 vs. 16.8%*), organ failure (71.8 vs. 46%*), and sepsis (17.5 vs. 10.6%*). Survival was worse (29.2 vs. 13.7%*). Comparison of the above models revealed hypothermia as an independent risk factor (Martin: OR, 1.43 [95% CI, 2.21-1.42*]; and Wang: OR, 1.77 [95% CI, 2.21-1.42*]) only, although it would drop out from the model (RISC: OR, 1.12 [95% CI, 1.41-0.89; P = 0.33] and Shafi: OR, 1,.21 [95% CI, 1.60-0.92; P = 0.17]) as long as parameters to indicate hemorrhage and/or coagulopathy were included in sufficient number, a finding confirmed by a subsequent sensitivity analysis. We conclude that hypothermia is a result of injury severity and therefore unlikely to be an independent predictor of mortality. Our data suggest that hypothermia belongs closely to the hemorrhage/coagulopathy group of predictors.

Perioperative Core Body Temperatures Effect on Outcome after Colorectal Resections

The World Health Organization has set a standard of maintaining a core body temperature above 36°C in the perioperative period. The purpose of this study was to examine the relationship between both intraoperative temperature (IOT) and immediate postop core body temperature as it relates to postop complications. A retrospective analysis of a prospective database of patients who underwent an elective segmental colectomy without a stoma, for 3 diagnoses was performed. Six postoperative outcomes were examined: length of stay (LOS), placement of a nasogastric tube, return to the operating room, placement of an interventional drain, diagnosed leak, and surgical site infection (SSI). Statistics were calculated using a two-sample Wilcoxon rank-sum (Mann-Whitney) test. Seventy-nine patients met the inclusion criteria and there were no preoperative differences between the groups (those with a postop complication vs without). LOS > 9 days (36.64°C vs 35.98°C; P = 0.011) and clinical leak (37.06°C vs 35.99°C; P = 0.005) both had a statistically higher average IOT than those who did not. Patients with SSI trended to a higher IOT (36.44°C vs 35.99°C; P = 0.062). When the last IOT recorded was compared with the six outcomes, again length of stay and leak both were statistically significant ( P = 0.018, P = 0.012) showing a higher temperature related to a higher complication rate. No other complications were related to IOT, nor did postop temperature relate to complication. In our data, relatively lower IOTs were protective for LOS and clinical leaks, with a trend of lower SSI rates. Further research is needed to fully endorse or refute the absolute recommendations for core body temperature.

Proteomic analysis of endothelial cold-adaptation

BACKGROUND

Understanding how human cells in tissue culture adapt to hypothermia may aid in developing new clinical procedures for improved ischemic and hypothermic protection. Human coronary artery endothelial cells grown to confluence at 37°C and then transferred to 25°C become resistant over time to oxidative stress and injury induced by 0°C storage and rewarming. This protection correlates with an increase in intracellular glutathione at 25°C. To help understand the molecular basis of endothelial cold-adaptation, isolated proteins from cold-adapted (25°C/72 h) and pre-adapted cells were analyzed by quantitative proteomic methods and differentially expressed proteins were categorized using the DAVID Bioinformatics Resource.

RESULTS

Cells adapted to 25°C expressed changes in the abundance of 219 unique proteins representing a broad range of categories such as translation, glycolysis, biosynthetic (anabolic) processes, NAD, cytoskeletal organization, RNA processing, oxidoreductase activity, response-to-stress and cell redox homeostasis. The number of proteins that decreased significantly with cold-adaptation exceeded the number that increased by 2:1. Almost half of the decreases were associated with protein metabolic processes and a third were related to anabolic processes including protein, DNA and fatty acid synthesis. Changes consistent with the suppression of cytoskeletal dynamics provided further evidence that cold-adapted cells are in an energy conserving state. Among the specific changes were increases in the abundance and activity of redox proteins glutathione S-transferase, thioredoxin and thioredoxin reductase, which correlated with a decrease in oxidative stress, an increase in protein glutathionylation, and a recovery of reduced protein thiols during rewarming from 0°C. Increases in S-adenosylhomocysteine hydrolase and nicotinamide phosphoribosyltransferase implicate a central role for the methionine-cysteine transulfuration pathway in increasing glutathione levels and the NAD salvage pathway in increasing the reducing capacity of cold-adapted cells.

CONCLUSIONS

Endothelial adaptation to mild-moderate hypothermia down-regulates anabolic processes and increases the reducing capacity of cells to enhance their resistance to oxidation and injury associated with 0°C storage and rewarming. Inducing these characteristics in a clinical setting could potentially limit the damaging effects of energy insufficiency due to ischemia and prevent the disruption of integrated metabolism at low temperatures.