Hypothermia in trauma patients

Efficacy of an Infrared Radiator for Hypothermia Prevention in a Simulated Setup of Entrapped Vehicle Accident Victims

BACKGROUND

Prolonged extrication of entrapped patients after road traffic accidents increases the risk of sustained hypothermia. Accident-related hypothermia increases mortality in severely injured patients, and prehospital efforts to prevent hypothermia are essential. We evaluated various warming measures regarding their preclinical suitability and efficacy for patient warming, tested in realistically-simulated road traffic accident scenarios under cold ambient conditions in a climate chamber.

METHODS

The effects of a chemical warming blanket (CWB), forced-air warming (FAW) device, or infrared radiator (IRR) on the core body and skin surface temperature of a subject previously exposed to a cold environment (5°C for 12 minutes) was recorded via temperature sensors and thermographically, respectively. Physiological parameters such as oxygen saturation, blood pressure, and heart rate were also monitored.

RESULTS

Under cold environmental conditions, all devices were able to compensate or overcompensate the cooling of body parts directly exposed to the heating measure. In the body areas that were not directly warmed (back, lower extremities), only the CWB limited further cooling. FAW and IR irradiation rapidly and effectively warmed the heat-exposed areas (head and arms). However, both methods - but especially the IRR - led to a noticeably accelerated cooling in body parts not directly exposed to heat (back, legs).

CONCLUSION

The increased mortality associated with hypothermia in severely injured crash victims during prolonged vehicle extrication has intensified efforts to prevent sustained hypothermia. The use of a CWB, FAW or IRR are in principle all suitable for reducing or compensating for heat loss. The ongoing cooling of those body parts not directly exposed to the heat source was interpreted as a steal phenomenon in regional blood flow. However, the practicality and effectiveness of these measures, combined with their logistical requirements, must be evaluated in real extrication scenarios.

Pre-hospital hypothermia is associated with transfusion risk after traumatic injury

OBJECTIVES

In traumatically injured patients, excessive blood loss necessitating the transfusion of red blood cell (RBC) units is common. Indicators of early RBC transfusion in the pre-hospital setting are needed. This study aims to evaluate the association between hypothermia (<36°C) and transfusion risk within the first 24 hours after arrival to hospital for a traumatic injury.

METHODS

We completed an audit of all traumatically injured patients who had emergent surgery at a single tertiary care center between 2010 and 2014. Using multivariable logistic regression analysis, we evaluated the association between pre-hospital hypothermia and transfusion of ≥1 unit of RBC within 24 hours of arrival to the trauma bay.

RESULTS

Of the 703 patients included to evaluate the association between hypothermia and RBC transfusion, 203 patients (29%) required a transfusion within 24 hours. After controlling for important confounding variables, including age, sex, coagulopathy (platelets and INR), hemoglobin, and vital signs (blood pressure and heart rate), hypothermia was associated with a 68% increased odds of transfusion in multivariable analysis (OR: 1.68; 95% CI: 1.11-2.56).

CONCLUSIONS

Hypothermia is strongly associated with RBC transfusion in a cohort of trauma patients requiring emergent surgery. This finding highlights the importance of early measures of temperature after traumatic injury and the need for intervention trials to determine if strategies to mitigate the risk of hypothermia will decrease the risk of transfusion and other morbidities.

A nomogram to predict arterial bleeding in patients with pelvic fractures after blunt trauma: a retrospective cohort study

Background

Pelvic bone fractures are one of the biggest challenges faced by trauma surgeons. Especially, the presence of bleeding and hemodynamic instability features is associated with high morbidity and mortality in patients with pelvic fractures. However, prediction of the occurrence of arterial bleeding causing massive hemorrhage in patients with pelvic fractures is difficult. Therefore, the aim of this study was to develop a nomogram to predict arterial bleeding in patients with pelvic bone fractures after blunt trauma.

Methods

The medical records of 1404 trauma patients treated between January 2013 and August 2017 were retrospectively reviewed. Patients older than 15 years with a pelvic fracture due to blunt trauma were enrolled (n = 148). The pelvic fracture pattern on anteroposterior radiography was classified according to the Orthopedic Trauma Association/Arbeitsgemeinschaft fur Osteosynthesefragen (OTA/AO) system. Multivariable logistic regression modeling was used to determine the independent risk factors for arterial bleeding. A nomogram was constructed based on the identified risk factors.

Results

The most common pelvic fracture pattern was type A (58.8%), followed by types B (34.5%) and C (6.7%). Of the 148 patients, 28 (18.9%) showed pelvic arterial bleeding on contrast-enhanced computed tomography or angiography, or in the operative findings. The independent risk factors for arterial bleeding were a type B or C pelvic fracture pattern, body temperature < 36 °C, and serum lactate level > 3.4 mmol/L. A nomogram was developed using these three parameters, along with a systolic blood pressure < 90 mmHg. The area under the receiver operating characteristic curve of the predictive model for discrimination was 0.8579. The maximal Youden index was 0.1527, corresponding to a cutoff value of 68.65 points, which was considered the optimal cutoff value for predicting the occurrence of arterial bleeding in patients with pelvic bone fractures.

Conclusions

The developed nomogram, which was based on the initial clinical findings identifying risk factors for arterial bleeding, is expected to be helpful in rapidly establishing a treatment plan and improving the prognosis for patients with pelvic bone fractures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02247-2.

Efficacy of warming systems in mountain rescue: an experimental manikin study

Mountain accident casualties are often exposed to cold and windy weather. This may induce post-traumatic hypothermia which increases mortality. The aim of this study was to assess the ability of warming systems to compensate for the victim's estimated heat loss in a simulated mountain rescue operation. We used thermal manikins and developed a thermodynamic model of a virtual patient. Manikins were placed on a mountain rescue stretcher and exposed to wind chill indices of 0 °C and - 20 °C in a climatic chamber. We calculated the heat balance for two simulated clinical scenarios with both a shivering and non-shivering victim and measured the heat gain from gel, electrical, and chemical warming systems for 3.5 h. The heat balance in the simulated shivering patient was positive. In the non-shivering patient, we found a negative heat balance for both simulated weather conditions (- 429.53 kJ at 0 °C and - 1469.78 kJ at - 20 °C). Each warming system delivered about 300 kJ. The efficacy of the gel and electrical systems was higher within the first hour than later (p < 0.001). We conclude that none of the tested warming systems is able to compensate for heat loss in a simulated model of a non-shivering patient whose physiological heat production is impaired during a prolonged mountain evacuation. Additional thermal insulation seems to be required in these settings.

Preoperative Warming Reduces Intraoperative Hypothermia in Total Joint Arthroplasty Patients

INTRODUCTION

Perioperative hypothermia (PH) is common in patients undergoing total joint arthroplasty (TJA). A previous study at our institution identified the largest drop in core body temperature between preoperative holding and induction of anesthesia. This study evaluates the effect of preoperative warming measures on PH in TJA patients.

METHODS

A retrospective review was conducted of 672 patients undergoing TJA at our institution between April 1 and October 31, 2017. Under the new normothermia protocol, patients received warmed intravenous fluids and forced-air warming gowns in the preoperative holding area. Time and temperature data for the perioperative period were collected from the electronic health record. Chi-square and paired t-tests were used to compare between total knee arthroplasty and total hip arthroplasty patients and between new and old protocols.

RESULTS

In the new protocol, 173 of 672 (26%) patients were hypothermic at incision compared with 140 of 383 (37%) patients in the previous protocol (P < 0.05). The largest drop in core body temperature occurred between preoperative holding and induction of anesthesia. The duration of time from operating room entry to incision was less for normothermic than for hypothermic patients. The duration of hypothermia was similar between new and old protocols overall, but markedly fewer total hip arthroplasty patients remained hypothermic for the entire surgery under the new protocol.

CONCLUSION

Adding forced-air warming preoperatively to our warming protocol reduced the rate of PH by approximately 30%. The time from entry into the operating room to the start of surgery should be minimized because patients are vulnerable to PH during this interval.

Effects of combined warmed preoperative forced-air and warmed perioperative intravenous fluids on maternal temperature during cesarean section: a prospective, randomized, controlled clinical trial

Background

Preventing the frequent perioperative hypothermia incidents that occur during elective caesarean deliveries would be beneficial. This trial aimed at evaluating the effect of preoperative forced-air warming alongside perioperative intravenous fluid warming in women undergoing cesarean sections under spinal anesthesia.

Methods

We randomly allocated 135 women undergoing elective cesarean deliveries to either the intervention group (preoperative forced-air and intravenous fluid warming, n = 69) or the control group (no active warming, n = 66). The primary outcome measure was the core temperature change between groups from baseline to the end of the surgical procedure. Secondary outcomes included thermal comfort scores, the incidences of shivering and hypothermia (< 36 °C), the core temperature on arrival at the post-anesthesia care unit, neonatal axillary temperature at birth, and Apgar scores.

Results

Two-way repeated measures ANOVA revealed significantly different core temperature changes (from the pre-spinal temperature to that at the end of the procedure) between groups (F = 13.022, P < 0.001). The thermal comfort scores were also higher in the intervention group than in the control group (F = 9.847, P = 0.002). The overall incidence of perioperative hypothermia was significantly lower in the intervention group than in the control group (20.6% vs. 51.6%, P < 0.0001).

Conclusions

Warming preoperative forced-air and perioperative intravenous fluids may prevent maternal hypothermia, reduce maternal shivering, and improve maternal thermal comfort for patients undergoing cesarean sections under spinal anesthesia.

Trial registration

The study was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR1800019117) on October26, 2018.

Effect of Thermal Insulation on Image Quality and Radiation Dose in Polytrauma Computed Tomography

PURPOSE

Unintentional drop in body temperature in trauma victims is an independent risk factor for mortality. We aimed to assess the impact of thermal insulation on image quality and radiation dose in polytrauma computed tomography (CT).

METHODS

Thirteen different insulating covers were used to wrap CT phantoms. Images were assessed subjectively at a radiological workstation and analyzed digitally with dedicated software evaluating the noise intensity, spatial resolution, and image homogeneity. The radiation dose was measured using a dosimeter.

RESULTS

Most materials did not cause significant artifacts apart from 2 heating pads. Although the radiation dose was increased by the majority of insulating covers (up to 64.66%), certain covers decreased the absorbed radiation (up to -7.35%).

CONCLUSIONS

The majority of insulating systems do not cause artifacts in CT scans. When using covers with self-heating warmers, removing the heating pad is suggested due to the risk of considerable artifacts appearing. Certain insulating covers may increase or decrease the radiation dose.

Factors predicting the need for hemorrhage control intervention in patients with blunt pelvic trauma: a retrospective study

Background

Blunt pelvic injuries are often associated with pelvic fractures and injuries to the rectum and genitourinary tract. Pelvic fractures can lead to life-threatening hemorrhage, which is a common cause of morbidity and mortality in trauma. Thus, early identification of patients with pelvic fractures at risk severe bleeding requiring urgent hemorrhage control is crucial. This study aimed to investigate early factors predicting the need for hemorrhage control in blunt pelvic trauma.

Methods

The medical records of 1760 trauma patients were reviewed retrospectively between January 2013 and June 2018. We enrolled 187 patients with pelvic fracture due to blunt trauma who were older than 15 years. The pelvic fracture pattern was classified according to the Orthopedic Trauma Association/Arbeitsgemeinschaft fur Osteosynthesefragen (OTA/AO) classification. A multivariate logistic regression model was used to determine independent predictors of the need for pelvic hemorrhage control intervention.

Results

The most common pelvic fracture pattern was type A (54.5%), followed by types B (36.9%) and C (8.6%). Of 187 patients, 48 (25.7%) required pelvic hemorrhage control intervention. Hemorrhage control interventions were most frequently performed in patients with type B fractures (54.2%). Multivariate logistic regression analysis revealed that type B (odds ratio [OR] = 4.024, 95% confidence interval [CI] = 1.666–9.720, p = 0.002) and C (OR = 7.077, 95% CI = 1.781–28.129, p = 0.005) fracture patterns, decreased body temperature (OR = 2.275, 95% CI = 0.134–0.567, p < 0.001), and elevated serum lactate level (OR = 1.234, 95% CI = 1.061–1.435, p = 0.006) were factors predicting the need for hemorrhage control intervention in patients with blunt pelvic trauma.

Conclusion

Patients with type B and C fracture patterns on the OTA/AO classification, hypothermia, or an elevated serum lactate level are at risk for bleeding and require pelvic hemorrhage control intervention.

Electronic supplementary material

The online version of this article (10.1186/s12893-018-0438-8) contains supplementary material, which is available to authorized users.

Perioperative management of the bleeding patient

Perioperative bleeding remains a major complication during and after surgery, resulting in increased morbidity and mortality. The principal causes of non-vascular sources of haemostatic perioperative bleeding are a preexisting undetected bleeding disorder, the nature of the operation itself, or acquired coagulation abnormalities secondary to haemorrhage, haemodilution, or haemostatic factor consumption. In the bleeding patient, standard therapeutic approaches include allogeneic blood product administration, concomitant pharmacologic agents, and increasing application of purified and recombinant haemostatic factors. Multiple haemostatic changes occur perioperatively after trauma and complex surgical procedures including cardiac surgery and liver transplantation. Novel strategies for both prophylaxis and therapy of perioperative bleeding include tranexamic acid, desmopressin, fibrinogen and prothrombin complex concentrates. Point-of-care patient testing using thromboelastography, rotational thromboelastometry, and platelet function assays has allowed for more detailed assessment of specific targeted therapy for haemostasis. Strategic multimodal management is needed to improve management, reduce allogeneic blood product administration, and minimize associated risks related to transfusion.

Hypothermia in Total Joint Arthroplasty: A Wake-Up Call

BACKGROUND

Total joint patients are particularly vulnerable to perioperative hypothermia (PH) (combined effects of anesthesia, radiation, and convective heat loss from exposed skin surfaces and cool temperatures in the operating room). There are limited studies on PH in these patients.

METHODS

In a retrospective review of 204 patients undergoing primary hip and 179 undergoing primary knee replacement surgeries, time and temperature parameters were collected from the electronic health records from preoperative and postoperative recovery room nursing assessments, intraoperative anesthesia records, and floor nursing notes. Basic patient demographic data was recorded. Chi-squared and paired t-tests were used to compare between hypothermic and normothermic groups.

RESULTS

At the time of incision, 60 of 179 (34%) total knee arthroplasty (TKA) patients and 80 of 204 (39%) total hip arthroplasty (THA) patients were hypothermic. In THA patients, 65% remained hypothermic for the duration of anesthesia compared to 33% of TKA patients. The largest drop in core body temperature in both THA and TKA patients occurred between preoperative holding and induction of anesthesia. In THA patients, spinal anesthesia had a significantly higher occurrence of PH. No significant patient factor was found to increase risk.

CONCLUSION

Emphasis on preoperative holding protocols, decreasing time from operating room entry to incision, and increasing ambient room temperature could reduce risk of hypothermia in total joint replacement patients.

Guiding Management in Severe Trauma: Reviewing Factors Predicting Outcome in Vastly Injured Patients

Trauma is one of the leading causes of death worldwide, with road traffic collisions, suicides, and homicides accounting for the majority of injury-related deaths. Since trauma mainly affects young age groups, it is recognized as a serious social and economic threat, as annually, almost 16,000 posttrauma individuals are expected to lose their lives and many more to end up disabled. The purpose of this research is to summarize current knowledge on factors predicting outcome - specifically mortality risk - in severely injured patients. Development of this review was mainly based on the systematic search of PubMed medical library, Cochrane database, and advanced trauma life support Guiding Manuals. The research was based on publications between 1994 and 2016. Although hypovolemic, obstructive, cardiogenic, and septic shock can all be seen in multi-trauma patients, hemorrhage-induced shock is by far the most common cause of shock. In this review, we summarize current knowledge on factors predicting outcome - more specifically mortality risk - in severely injured patients. The main mortality-predicting factors in trauma patients are those associated with basic human physiology and tissue perfusion status, coagulation adequacy, and resuscitation requirements. On the contrary, advanced age and the presence of comorbidities predispose patients to a poor outcome because of the loss of physiological reserves. Trauma resuscitation teams considering mortality prediction factors can not only guide resuscitation but also identify patients with high mortality risk who were previously considered less severely injured.

Preventative measures taken against hypothermia in selected Durban hospitals' emergency centres and operating theatres

Introduction

Hypothermia is common in emergency general surgical patients. It is known to be associated with major complications in multiple organ systems. It is also easily preventable with the use of safe and cost-effective equipment. However, by observation, it appears that this equipment is used too infrequently thus resulting in unnecessary harm to patients.

Methods

This descriptive, observational, cross-sectional study was conducted in two arms to evaluate both emergency centres and operating theatres in the major state hospitals in Durban. It was conducted as an audit as well as a questionnaire-based study, to ascertain the availability of equipment used to prevent hypothermia and also how appropriately the equipment was being used.

Results

There was good availability of equipment in both the operating theatres and the emergency centres. However it was being used very poorly, particularly in emergency centres (41% of responses deemed not beneficial to patients versus 29% from operating theatres; 39% of answers beneficial versus 54% from operating theatres). Institutions with hypothermia-prevention protocols scored significantly better than those without a protocol (59% versus 25% beneficial; p = 0.01).

Conclusion

In the field of hypothermia prevention, there was sufficient equipment to result in optimal patient care. However there appears to be a lack of knowledge amongst health care providers, resulting in suboptimal use of this equipment. Protocolised management may provide a solution to this problem and improve patient outcomes.

Assessment and Resuscitation in Trauma Management

The golden hour of trauma represents a crucial period in the management of acute injury. In an efficient trauma resuscitation, the primary survey is viewed as more than simple ABCs with multiple processes running in parallel. Resuscitation efforts should be goal oriented with defined endpoints for airway management, access, and hemodynamic parameters. In tandem with resuscitation, early identification of life-threatening injuries is critical for determining the disposition of patients when they leave the trauma bay. Salvage strategies for profoundly hypotensive or pulseless patients include retrograde balloon occlusion of the aorta and resuscitative thoracotomy, with differing populations benefiting from each.

Damage Control Resuscitation for Catastrophic Bleeding

The timely recognition of shock secondary to hemorrhage from severe facial trauma or as a complication of complex oral and maxillofacial surgery presents formidable challenges. Specific hemostatic disorders are induced by hemorrhage and several extreme homeostatic imbalances may appear during or after resuscitation. Damage control resuscitation has evolved from massive transfusion to a more complex therapeutic paradigm that includes hemodynamic resuscitation, hemostatic resuscitation, and homeostatic resuscitation. Definitive control of bleeding is the principal objective of any comprehensive resuscitation scheme for hemorrhagic shock.

Hemodynamic Stability to Surface Warming and Cooling During Sustained and Continuous Simulated Hemorrhage in Humans

One in 10 deaths worldwide is caused by traumatic injury, and 30% to 40% of those trauma-related deaths are due to hemorrhage. Currently, warming a bleeding victim is the standard of care due to the adverse effects of combined hemorrhage and hypothermia on survival. We tested the hypothesis that heating is detrimental to the maintenance of arterial pressure and cerebral perfusion during hemorrhage, while cooling is beneficial to victims who are otherwise normothermic. Twenty-one men (31 ± 9 y) were examined under two separate protocols designed to produce central hypovolemia similar to hemorrhage. Following 15 min of supine rest, 10 min of 30 mm Hg of lower body negative pressure (LBNP) was applied. On separate randomized days, subjects were then exposed to skin surface cooling (COOL), warming (WARM), or remained thermoneutral (NEUT), while LBNP continued. Subjects remained in these thermal conditions for either 40 min of 30 mm Hg LBNP (N = 9), or underwent a continuous LBNP ramp until hemodynamic decompensation (N = 12). Arterial blood pressure during LBNP was dependent on the thermal perturbation as blood pressure was greater during COOL (P >0.001) relative to NEUT and WARM for both protocols. Middle cerebral artery blood velocity decreased (P <0.001) from baseline throughout sustained and continuous LBNP, but the magnitude of reduction did not differ between thermal conditions. Contrary to our hypothesis, WARM did not reduce cerebral blood velocity or LBNP tolerance relative to COOL and NEUT in normothermic individuals. While COOL increased blood pressure, cerebral perfusion and time to presyncope were not different relative to NEUT or WARM during sustained or continuous LBNP. Warming an otherwise normothermic hemorrhaging victim is not detrimental to hemodynamic stability, nor is this stability improved with cooling.

A recommended early goal-directed management guideline for the prevention of hypothermia-related transfusion, morbidity, and mortality in severely injured trauma patients

Hypothermia is present in up to two-thirds of patients with severe injury, although it is often disregarded during the initial resuscitation. Studies have revealed that hypothermia is associated with mortality in a large percentage of trauma cases when the patient's temperature is below 32 °C. Risk factors include the severity of injury, wet clothing, low transport unit temperature, use of anesthesia, and prolonged surgery. Fortunately, associated coagulation disorders have been shown to completely resolve with aggressive warming. Selected passive and active warming techniques can be applied in damage control resuscitation. While treatment guidelines exist for acidosis and bleeding, there is no evidence-based approach to managing hypothermia in trauma patients. We synthesized a goal-directed algorithm for warming the severely injured patient that can be directly incorporated into current Advanced Trauma Life Support guidelines. This involves the early use of warming blankets and removal of wet clothing in the prehospital phase followed by aggressive rewarming on arrival at the hospital if the patient's injuries require damage control therapy. Future research in hypothermia management should concentrate on applying this treatment algorithm and should evaluate its influence on patient outcomes. This treatment strategy may help to reduce blood loss and improve morbidity and mortality in this population of patients.

A torso model comparison of temperature preservation devices for use in the prehospital environment

BACKGROUND

Hypothermia is an independent predictor of increased morbidity and mortality in patients with trauma. Several strategies and products have been developed to minimise patients' heat loss in the prehospital arena, but there is little evidence to inform the clinician concerning their effectiveness.

METHODS

We used a human torso model consisting of two 5.5-litre fluid bags to simultaneously compare four passive (space blanket, bubble wrap, Blizzard blanket, ambulance blanket) and one active (Ready-Heat II blanket) temperature preservation products. A torso model without any temperature preservation device provided a control. For each test, the torso models were warmed to 37°C and left outdoors. Core temperatures were recorded every 10 min for 1 h in total; tests were repeated 10 times.

RESULTS

A significant difference in temperature was detected among groups at 30 and 60 min (F (1.29, 10.30)=103.58, p<0.001 and F (1.64, 14.78)=163.28, p<0.001, respectively). Mean temperature reductions (95% CI) after 1 h of environmental exposure were the following: 11.6 (10.3 to 12.9) °C in control group, 4.5 (3.9 to 5.1) °C in space blanket group, 3.6 (3 to 4.3) °C in bubble-wrap group, 2.1 (1.7 to 2.5) °C in Blizzard blanket group, 6.1 (5.8 to 6.5) °C in ambulance blanket group and 1.1 (0.7 to 1.6) °C in Ready-Heat II blanket group.

CONCLUSIONS

In this study, using a torso model based on two 5 L dialysate bags we found the Ready-Heat II heating blanket and Blizzard blanket were associated with lower rates of heat loss after 60 min environmental exposure than the other devices tested.

Damage control resuscitation

The early recognition and management of hemorrhage shock are among the most difficult tasks challenging the clinician during primary assessment of the acutely bleeding patient. Often with little time, within a chaotic setting, and without sufficient clinical data, a decision must be reached to begin transfusion of blood components in massive amounts. The practice of massive transfusion has advanced considerably and is now a more complete and, arguably, more effective process. This new therapeutic paradigm, referred to as damage control resuscitation (DCR), differs considerably in many important respects from previous management strategies for catastrophic blood loss. We review several important elements of DCR including immediate correction of specific coagulopathies induced by hemorrhage and management of several extreme homeostatic imbalances that may appear in the aftermath of resuscitation. We also emphasize that the foremost objective in managing exsanguinating hemorrhage is always expedient and definitive control of the source of bleeding.

Does close temperature regulation affect surgical site infection rates?

The argument for close temperature control, to which regulatory bodies have held health systems in an effort to reduce the burden of hospital-acquired infections, is not fully supported by current evidence. The literature is complex on the topic, and overinterpretation of historical data supporting close temperature regulation does not preclude an important recognition of these early works' contribution to high-quality surgical care. Avoidance of hypothermia through the regular use of active rewarming should be a routine part of safe surgical care. The biochemical basis of emphasizing temperature regulation is sound, and ample evidence shows the frank physiologic derangements seen when biological processes occur at suboptimal temperature. It is also recognized that patients tend to do better when warmed during the perioperative period, suggesting that warming devices are an important and essential adjunct to good perioperative care. Clinicians, researchers, and policymakers must be careful in how they apply these well-supported findings to process metrics in an era of limited resources with increasingly stringent quality guidelines and outcomes measures. Discrete temperature targets in current measures are not supported by the existing literature. Not only do these targets artificially anchor clinicians to temperature values with an inadequate scientific basis but they demand intensive resources from health institutions that could potentially be better used on quality requirements with stronger evidence of their ultimate effect on patient care.

The effect of controlled mild hypothermia on large scald burns in a resuscitated rat model

OBJECTIVE

Early surface cooling of burns reduces pain, depth of injury and improves healing. We hypothesized that controlled mild hypothermia would also prolong survival in a fluid resuscitated rat model of large scald burns.

METHODS

Forty rats were anesthetized and a single full-thickness scald burn covering 40% of total body surface area was created on each of the rats. The rats were then randomized to hypothermia (n=20) or no hypothermia (n=20). Mild hypothermia (a reduction of 2°C) was induced with intraperitoneal 4°C normal saline and ice packs. After 2 hours of hypothermia, the rats were rewarmed back to their baseline temperature with a heating pad. The control rats received room temperature intraperitoneal saline. The difference in survival between the groups was determined using Kaplan-Meier analysis and the log-rank test.

RESULTS

Hypothermia was induced in all experimental rats within a mean of 22 minutes (95% confidence interval, 17 to 27). The number of normothermic and hypothermic rats that expired at each time interval were: at 1 hour, 4 vs. 0; at 10 hours, 2 from each group; at 24 hours, 0 vs. 1; at 48 hours, 2 vs. 2; at 72 hours, 1 vs. 1; and at 120 hours, 1 vs. 1 respectively. There were no differences in time to survival between the groups.

CONCLUSION

Induction of brief, mild hypothermia does not prolong survival in a resuscitated rat model of large scald burns.

Effects of different fluid regimes and desmopressin on uncontrolled hemorrhage during hypothermia in the rat

Resuscitation with large volumes of crystalloids during traumatic hemorrhagic shock might increase the mortality by inducing rebleeding. However, few studies have addressed this problem during hypothermic conditions. Sixty-eight Sprague-Dawley rats were exposed to a standardized femoral artery injury and resuscitated with low (LRe), medium (MRe), or high (HRe) intensity using lactated Ringer's solution after being cooled to 30°C. An additional MRe group was also given desmopressin since this drug might reverse hypothermic-induced impairment of the primary hemostasis. The rats were rewarmed after 90 minutes and observed for 3 hours. The incidence, on-set time, duration, and volume of bleedings and hemodynamic changes were recorded. Rebleedings occurred in 60% of all animals and were more voluminous in the HRe group than in the LRe group (p=0.01). The total rebleeding volume per animal increased with the rate of fluid administration (r=0.50, p=0.01) and the duration of each rebleeding episode was longer in the HRe group than in the LRe group (p<0.001). However, the mortality tended to be higher in the LRe group (LRe=6/15, MRe=1/15, HRe=2/15, p=0.07). Desmopressin did not change the bled volume or the mortality. Overall, the mortality increased if rebleeding occurred (10/35 rebleeders died vs. 1/25 nonrebleeders, p=0.015). Liberal fluid administration increased the rebleeding volume while a trend toward higher mortality was seen with the restrictive fluid program. Desmopressin had no effect on the studied parameters.

Minimising blood loss in early trauma resuscitation

Worldwide, trauma is responsible for more than 10,000 deaths each day with hundreds of thousands seriously injured. Current trauma resuscitation strategies are based on supporting haemostasis, maintaining circulating volume and rapidly identifying sites of blood loss. Approaches include hypotensive/hypovolaemic resuscitation, avoidance of colloids and crystalloids, early blood product based resuscitation, early imaging to identify sites of blood loss and damage control surgery. In this paper, we focus on ways to minimise blood loss and preserve the circulating volume. These include minimal movement of the patient, splinting fractures, use of tourniquets, application of local haemostatic dressings/agents, keeping the patient warm and giving tranexamic acid to improve clot strength. The recent CRASH-2 trial provided unequivocal evidence that tranexamic acid reduces mortality in bleeding trauma patients. This will be discussed in detail. When employed as part of a package of care in a well-rehearsed trauma system, these interventions to preserve the remaining circulating volume have the potential to save lives and allow patients to survive until timely definitive haemostasis can occur.

Patients' experiences of cold exposure during ambulance care

Background

Exposure to cold temperatures is often a neglected problem in prehospital care. Cold exposure increase thermal discomfort and, if untreated causes disturbances of vital body functions until ultimately reaching hypothermia. It may also impair cognitive function, increase pain and contribute to fear and an overall sense of dissatisfaction. The aim of this study was to investigate injured and ill patients’ experiences of cold exposure and to identify related factors.

Method

During January to March 2011, 62 consecutively selected patients were observed when they were cared for by ambulance nursing staff in prehospital care in the north of Sweden. The field study was based on observations, questions about thermal discomfort and temperature measurements (mattress air and patients’ finger temperature). Based on the observation protocol the participants were divided into two groups, one group that stated it was cold in the patient compartment in the ambulance and another group that did not. Continuous variables were analyzed with independent sample t-test, paired sample t-test and dichotomous variables with cross tabulation.

Results

In the ambulance 85% of the patients had a finger temperature below comfort zone and 44% experienced the ambient temperature in the patient compartment in the ambulance to be cold. There was a significant decrease in finger temperature from the first measurement indoor compared to measurement in the ambulance. The mattress temperature at the ambulance ranged from −22.3°C to 8.4°C.

Conclusion

Cold exposure in winter time is common in prehospital care. Sick and injured patients immediately react to cold exposure with decreasing finger temperature and experience of discomfort from cold. Keeping the patient in the comfort zone is of great importance. Further studies are needed to increase knowledge which can be a base for implications in prehospital care for patients who probably already suffer for other reasons.

Reactions to Cold Exposure Emphasize the Need for Weather Protection in Prehospital Care: An Experimental Study

Introduction:

Exposure to cold temperature is a serious but often neglected problem in prehospital care. It not only is an uncomfortable, subjective experience, but it also can cause severe disturbances in vital functions, gradually leading to hypothermia.

Objective:

The aim of this study was to examine healthy subjects'physiological and subjective reactions to cold exposure (30 minutes at -5°C in the a climatic chamber) while they were lying in a protective covering.

Methods:

Healthy volunteers (n = 20) participated in the experiment, which consisted of a 10-minute stabilization period of vital functions at room temperature (23°C), 30 minutes of cold exposure (-5°C), and a 30-minute recovery period at room temperature. Subjects lay supinely in protective covering during the entire experiment. Skin temperatures, oxygen saturation, pulse rates, pulse wave amplitude in the middle finger, and surface electromyography (EMG) activity of the major pectoral muscle were recorded continuously during the test. Before and immediately after the cold exposure, tympanic membrane temperatures were measured. In addition, subjects were asked to estimate cold using a standard scale.

Results:

During the cold exposure, the decrease in tympanic membrane temperature was not significant.The pulse wave amplitude in the finger decreased sharply upon entering the cold chamber. Skin temperatures, especially of the fingers and toes, decreased during the cold exposure.There were no clear signs of shivering in electromyographic recordings. Subjective cold feelings followed decreasing skin temperatures. Skin temperatures did not return quickly. Even 30 minutes after the exposure, all the skin temperatures still had not returnedto normal levels.However, subjective cold feeling was relieved immediately.

Conclusions:

Cold exposure provoked immediate protective vasoconstriction in the peripheral compartment, which caused linear decreases of local skin temperatures. This probably was triggered from the unprotected face and upper respiratory areas.

Hypothermia increases rebleeding during uncontrolled hemorrhage in the rat

Trauma registers show that hypothermia (HT) is an independent risk factor for death during hemorrhagic shock, although experimental animal studies indicate that HT may be beneficial during these conditions. However, the animal models were not designed to detect the expected increase in bleeding caused by HT. In a new model for uncontrolled bleeding, 40 Sprague-Dawley rats were exposed to a standardized femoral artery injury and randomized to either normothermia or HT. Ketamine/midazolam was used to minimize hemodynamic changes due to the anesthesia. The hypothermic rats were cooled to 30°C and rewarmed again at 90 min. The study period was 3 h. The incidence, onset time, duration, and volume of bleedings as well as hemodynamic and metabolic changes were recorded. There was no difference between groups with respect to the initial bleeding. Rebleedings occurred among 60% of the animals in both groups. Hypothermic rebleeders had more, larger, and longer rebleedings, resulting in a total rebleeding volume amounting to 41% of their estimated blood volume. The corresponding figure for the normothermic rebleeders was 3% (P < 0.001). Total rebleeding volume was significantly larger in the hypothermic group, even at body temperatures greater than 35°C. We conclude that the risk of rebleeding from a femoral injury is greater in the presence of cooling and HT. The larger rebleeding volumes seen even at body temperatures greater than 35°C indicate that factors other than temperature-induced coagulopathy also contributed to the increased hemorrhage.

Comparing ambient, air-convection, and fluid-convection heating techniques in treating hypothermic burn patients, a clinical RCT

Background

Hypothermia in burns is common and increases morbidity and mortality. Several methods are available to reach and maintain normal core body temperature, but have not yet been evaluated in critical care for burned patients. Our unit's ordinary technique for controlling body temperature (Bair Hugger^®+ radiator ceiling + bed warmer + Hotline^®) has many drawbacks e.g.; slow and the working environment is hampered.

The aim of this study was to compare our ordinary heating technique with newly-developed methods: the Allon™2001 Thermowrap (a temperature regulating water-mattress), and Warmcloud (a temperature regulating air-mattress).

Methods

Ten consecutive burned patients (> 20% total burned surface area and a core temperature < 36.0°C) were included in this prospective, randomised, comparative study. Patients were randomly exposed to 3 heating methods. Each treatment/measuring-cycle lasted for 6 hours. Each heating method was assessed for 2 hours according to a randomised timetable. Core temperature was measured using an indwelling (bladder) thermistor. Paired t-tests were used to assess the significance of differences between the treatments within the patients. ANOVA was used to assess the differences in temperature from the first to the last measurement among all treatments. Three-way ANOVA with the Tukey HSD post hoc test and a repeated measures ANOVA was used in the same manner, but included information about patients and treatment/measuring-cycles to control for potential confounding. Data are presented as mean (SD) and (range). Probabilities of less than 0.05 were accepted as significant.

Results

The mean increase, 1.4 (SD 0.6°C; range 0.6-2.6°C) in core temperature/treatment/measuring-cycle highly significantly favoured the Allon™2001 Thermowrap in contrast to the conventional method 0.2 (0.6)°C (range -1.2 to 1.5°C) and the Warmcloud 0.3 (0.4)°C (range -0.4 to 0.9°C). The procedures for using the Allon™2001 Thermowrap were experienced to be more comfortable and straightforward than the conventional method or the Warmcloud.

Conclusions

The Allon™2001 Thermowrap was more effective than the Warmcloud or the conventional method in controlling patients' temperatures.

Controlled mild hypothermia prolongs survival in a rat model of large scald burns

OBJECTIVES

Early surface cooling of burns reduces pain and depth of injury and improves healing. However, there are concerns that cooling of large burns may result in hypothermia and worsen outcomes. In contrast, controlled mild hypothermia improves outcomes after cardiac arrest and traumatic brain injury. The authors hypothesized that controlled mild hypothermia would prolong survival in a rat model of large scald burns.

METHODS

Thirty-six Sprague-Dawley rats (250-300 g) were anesthetized with 40 mg/kg intramuscular ketamine and 5 mg/kg xylazine, with supplemental inhalational isoflurane as needed. A single full-thickness scald burn covering 40% of total body surface area was created on each of the rats using a Mason-Walker template placed in boiling water (100 °C) for a period of 10 seconds. The rats were then randomized to hypothermia (n = 18) or no hypothermia (n = 18). Core body temperature was continuously monitored with a rectal temperature probe. In the experimental group, mild hypothermia was induced by applying ice packs over the prone rats until their rectal temperature was reduced by 2 °C for a period of 2 hours. After 2 hours of hypothermia, the rats were rewarmed back to their baseline temperature with a heating pad. The control rats were not cooled. The rats were monitored until death or for a period of 7 days, whichever was greater. The primary outcome was time to death. The difference in survival between the groups was determined using Kaplan-Meier analysis and the log-rank test.

RESULTS

  Hypothermia was induced in all experimental rats within a mean of 22 minutes (95% confidence interval [CI] = 17 to 27). The numbers of nonhypothermic and hypothermic rats that were dead at each time point were as follows: 2 hours, five versus none; 18 hours, 16 versus five; 24 hours, 18 versus eight; and 48 hours, 18 versus 13 (p = 0.05). There were no additional deaths after 48 hours. The mean time to survival of the hypothermic rats was significantly greater than that of the nonhypothermic rats (p < 0.001).

CONCLUSIONS

Induction of brief, mild hypothermia prolongs survival and increases the survival rate in nonresuscitated rats with large scald burns.

In vitro study of variables relevant to perioperative care of the surgical patient: glucose, osmolarity, and rewarming

BACKGROUND

We sought to determine the effects of altering osmolarity and the reversibility of the detrimental immunologic effects of hypothermia on human monocyte HLA-DR surface expression and reactive oxygen species (ROS) formation.

STUDY DESIGN

The effects of altering osmolarity on HLA-DR surface expression and ROS formation were assessed using lipopolysaccharide (LPS)-treated samples treated with either saline, glucose, or mannitol, incubated at 37°C for 2 hours. HLA-DR surface receptor expression and ROS formation were determined after incubation. The effects of the reversibility of hypothermia were measured by incubating LPS-treated samples at 34°C, 37°C, and 40°C for 1 hour. The samples were subsequently rewarmed at 40°C for 1 and 2 hours. The effects of rewarming on HLA-DR surface receptor expression and ROS formation were reassessed.

RESULTS

In the osmolarity experiments, there was a 49% decrease in ROS formation in samples treated with mannitol as compared with saline and glucose. Alterations of osmolarity had no significant effect on HLA-DR surface expression. In the rewarming experiments, rewarming for either 1 or 2 hours abolished any significant differences in HLA-DR surface expression and ROS formation between samples preincubated at the different temperatures.

CONCLUSIONS

The presumed inert mannitol was found to significantly decrease ROS formation, but had no effect on HLA-DR surface expression. In addition, the effects of hypothermia on HLA-DR surface expression or ROS formation may be better reversed within 2 hours than in 1 hour.

The incidence and significance of accidental hypothermia in major trauma--a prospective observational study

BACKGROUND

Serious sequelae have been associated with injured patients who are hypothermic (<35°C) including coagulopathy, acidosis, decreased myocardial contractility and risk of mortality.

AIM

Establish the incidence of accidental hypothermia in major trauma patients and identify causative factors.

METHOD

Prospective identification and subsequent review of 732 medical records of major trauma patients presenting to an Adult Major Trauma Centre was undertaken between January and December 2008. Multivariate analysis was performed using logistic regression. Significant and clinically relevant variables from univariate analysis were entered into multivariate models to evaluate determinants for hypothermia and for death. Goodness of fit was determined with the use of the Hosmer-Lemeshow statistic.

MAIN RESULTS

Overall mortality was 9.15%. The incidence of hypothermia was 13.25%. The mortality of patients with hypothermia was 29.9% with a threefold independent risk of death: OR (CI 95%) 3.44 (1.48-7.99), P = 0.04. Independent determinants for hypothermia were pre-hospital intubation: OR (CI 95%) 5.18 (2.77-9.71), P < 0.001, Injury Severity Score (ISS): 1.04 (1.01-1.06), P = 0.01, Arrival Systolic Blood Pressure (ASBP) < 100 mm Hg: 3.04 (1.24-7.44), P = 0.02, and winter time: 1.84 (1.06-3.21), P = 0.03. Of the 87 hypothermic patients who had repeat temperatures recorded in the Emergency Department, 77 (88.51%) patients had a temperature greater than the recorded arrival temperature. There was no change in recorded temperature for four (4.60%) patients, whereas six (6.90%) patients were colder at Emergency Department discharge.

CONCLUSION

Seriously injured patients with accidental hypothermia have a higher mortality independent of measured risk factors. For patients with multiple injuries a coordinated effort by paramedics, nurses and doctors is required to focus efforts toward early resolution of hypothermia aiming to achieve a temperature >35 °C.

Management of liver trauma

BACKGROUND

Blunt and penetrating liver trauma is common and often presents major diagnostic and management problems.

METHODS

A literature review was undertaken to determine the current consensus on investigation and management strategies.

RESULTS

The liver is the most frequently injured organ following abdominal trauma. Immediate assessment with ultrasound has replaced diagnostic peritoneal lavage in the resuscitation room, but computerised tomography remains the gold standard investigation. Nonoperative management is preferred in stable patients but laparotomy is indicated in unstable patients. Damage control techniques such as perihepatic packing, hepatotomy plus direct suture, and resectional debridement are recommended. Major complex surgical procedures such as anatomical resection or atriocaval shunting are now thought to be redundant in the emergency setting. Packing is also recommended for the inexperienced surgeon to allow control and stabilisation prior to transfer to a tertiary centre. Interventional radiological techniques are becoming more widely used, particularly in patients who are being managed nonoperatively or have been stabilised by perihepatic packing.

CONCLUSIONS

Management of liver injuries has evolved significantly throughout the last two decades. In the absence of other abdominal injuries, operative management can usually be avoided. Patients with more complex injuries or subsequent complications should be transferred to a specialist centre to optimise final outcome.

Management of liver trauma

BACKGROUND

Blunt and penetrating liver trauma is common and often presents major diagnostic and management problems.

METHODS

A literature review was undertaken to determine the current consensus on investigation and management strategies.

RESULTS

The liver is the most frequently injured organ following abdominal trauma. Immediate assessment with ultrasound has replaced diagnostic peritoneal lavage in the resuscitation room, but computerised tomography remains the gold standard investigation. Nonoperative management is preferred in stable patients but laparotomy is indicated in unstable patients. Damage control techniques such as perihepatic packing, hepatotomy plus direct suture, and resectional debridement are recommended. Major complex surgical procedures such as anatomical resection or atriocaval shunting are now thought to be redundant in the emergency setting. Packing is also recommended for the inexperienced surgeon to allow control and stabilisation prior to transfer to a tertiary centre. Interventional radiological techniques are becoming more widely used, particularly in patients who are being managed nonoperatively or have been stabilised by perihepatic packing.

CONCLUSIONS

Management of liver injuries has evolved significantly throughout the last two decades. In the absence of other abdominal injuries, operative management can usually be avoided. Patients with more complex injuries or subsequent complications should be transferred to a specialist centre to optimise final outcome.

Article Commentary: Optimizing Surgical Care: A Contemporary Assessment of Temperature, Oxygen, and Glucose

Factors such as temperature, oxygen, and glucose have recently been implicated in the development of surgical sepsis by either promoting or attenuating protective components of the innate immune response. Reducing infective sequelae and the improvement of the quality of care of surgical patients is a top practice priority today. These factors and their associated effects are discussed through the examination of recent clinical and scientific studies to provide an up-to-date evidence-based review.

The association between hypothermia, prehospital cooling, and mortality in burn victims

OBJECTIVES

Hypothermia is associated with increased morbidity and mortality in trauma victims. The prognostic value of hypothermia on emergency department (ED) presentation in burn victims is not well known. The objective of this study was to determine the incidence of hypothermia in burn victims and its association with mortality and hospital length of stay (LOS). The study also examined the potential causative role of prehospital cooling in hypothermic burn patients.

METHODS

This was a retrospective review of a county trauma registry. The county was both suburban and rural, with a population of 1.5 million and with one burn center. Burn patients between 1994 and 2007 who met trauma registry criteria were included. Demographic and clinical data including prehospital cooling, burn size and depth, and presence of inhalation injury were collected. Hypothermia was defined as a core body temperature of less than or equal to 35 degrees C. Data analysis consisted of univariate associations between patient characteristics and hypothermia.

RESULTS

There were 1,215 burn patients from 1994 to 2007. Mean age (+/-standard deviation [+/-SD]) was 29 (+/-24) years, 67% were male, 248 (26.7%) had full-thickness burns, and 24 (2.6%) had inhalation injury. Only 17 (1.8%) had a burn larger than 70% total body surface area (TBSA). A total of 929 (76%) patients had an initial ED temperature recorded. Only 15/929 (1.6%) burn patients had hypothermia on arrival, and all were mild (lowest temperature was 32.6 degrees C). There was no association between sex, year, and presence of inhalation injury with hypothermia. Hypothermic patients were older (44 years vs. 29 years, p = 0.01), and median Injury Severity Score (ISS) was higher (25 vs. 4, p = 0.002) than for nonhypothermic patients. Hypothermia was present in 6/17 (35%) patients with a TBSA of 70% or greater and in 8/869 (0.9%) patients with a TBSA of <70% (p < 0.001). Mortality was higher in hypothermic patients (60% vs. 3%, p < 0.001). None of the hypothermic patients received prehospital cooling.

CONCLUSIONS

Hypothermia on presentation to the ED was noted in 1.6% of all burn victims in this trauma registry. Hypothermia was more common in very large burns and was associated with high mortality. In this series, prehospital cooling did not appear to contribute to hypothermia.

[Liver injuries]

The liver is the most commonly injured abdominal organ. Severe hepatic trauma continue to be associated with high mortality. Management of liver injuries has changed significantly over the last two decades. Nonoperative management of hemodynamically stable patients has become the first treatment of choice. In unstable patients immediate control of bleeding is critical. In the management of severe injuries of the liver, particularly for patients who had developed a metabolic insult (hypothermia, coagulopathy, and acidosis), perihepatic packing has emerged as the key to effective damage control (DCS). The surgical aim is control of hemorrhage, preservation of sufficient hepatic function and prevention of secondary complications. Currently available surgical methods include hepatorrhaphy, resectional debridement, anatomical/nonanatomical resection, selective hepatic artery ligation, Pringle maneuver, total vascular exclusion, liver transplatation. This review discusses available diagnostic modalities and the best management options for liver injury, based on literature search and authors experience.