The effect of active warming in prehospital trauma care during road and air ambulance transportation - a clinical randomized trial

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.

Outcomes of Trauma "Walk-Ins" in the American College of Surgeons Trauma Quality Program Database

BACKGROUND

Outcomes of trauma "walk-in" patients (using private vehicles or on foot) are understudied. We compared outcomes of ground ambulance vs walk-ins, hypothesizing that delayed resuscitation and uncoordinated care may worsen walk-in outcomes.

METHODS

A retrospective analysis 2020 American College of Surgeons Trauma Quality Programs (ACS-TQP) databases compared outcomes between ambulance vs "walk-ins." The primary outcome was in-hospital mortality, excluding external facility transfers and air transports. Data was analyzed with descriptive statistics, bivariate, multivariable logistic regression, including an Inverse Probability Weighted Regression Adjustment with adjustments for injury severity and vital signs. The primary outcome for the 2019 (pre-COVID-19 pandemic) data was similarly analyzed.

RESULTS

In 2020, 707,899 patients were analyzed, 556,361 (78.59%) used ambulance, and 151,538 (21.41%) were walk-ins. We observed differences in demographics, hospital attributes, medical comorbidities, and injury mechanism. Ambulance patients had more chronic conditions and severe injuries. Walk-ins had lower in-hospital mortality (850 (.56%) vs 23,131 (4.16%)) and arrived with better vital signs. Multivariable logistic regression models (inverse probability weighting for regression adjustment), adjusting for injury severity, demographics, injury mechanism, and vital signs, confirmed that walk-in status had lower odds of mortality. For the 2019 (pre-COVID-19 pandemic) database, walk-ins also had lower in-hospital mortality.

DISCUSSION

Our results demonstrate better survival rates for walk-ins before and during COVID-19 pandemic. Despite limitations of patient selection bias, this study highlights the need for further research into transportation modes, geographic and socioeconomic factors affecting patient transport, and tailoring management strategies based on their mode of arrival.

What is the best way to keep the patient warm during technical rescue? Results from two prospective randomised controlled studies with healthy volunteers

BACKGROUND

Accidental hypothermia is a manifest problem during the rescue of entrapped victims and results in different subsequent problems as coagulopathy and wound infection. Different warming methods are available for the preclinicial use. However, their effectiveness has hardly been evaluated.

METHODS

In a first step a survey among German fire brigades was performed with questions about the most used warming methods. In a second step two crossover studies were conducted. In each study two different warming method were compared with forced air warming - which is the most frequently used and highly effective warming method in operation rooms (Study A: halogen floodlight vs. forced air warming; Study B: forced air warming vs. fleece blanket). In both studies healthy volunteers (Study A: 30 volunteers, Study B: 32 volunteers) were sitting 60 min in a cold store. In the first 21 min there was no subject warming. Afterwards the different warming methods were initiated. Every 3 min parameters like skin temperature, core body temperature and cold perception on a 10-point numeric rating scale were recorded. Linear mixed models were fitted for each parameter to check for differences in temperature trajectories and cold perception with regard to the different warming methods.

RESULTS

One hundred fifty-one German fire brigades responded to the survey. The most frequently used warming methods were different rescue blankets (gold/silver, wool) and work light (halogen floodlights). Both studies (A and B) showed significantly (p < 0.05) higher values in mean skin temperature, mean body temperature and total body heat for the forced air warming methods compared to halogen floodlight respectively fleece blanket shortly after warming initiation. In contrast, values for the cold perception were significantly lower (less unpleasant cold perception) during the phase the forced air warming methods were used, compared to the fleece blanket or the halogen floodlight was used.

CONCLUSION

Forced air warming methods used under the standardised experimental setting are an effective method to keep patients warm during technical rescue. Halogen floodlight has an insufficient effect on the patient's heat preservation. In healthy subjects, fleece blankets will stop heat loss but will not correct heat that has already been lost.

TRIAL REGISTRATION

The studies were registered retrospectively on 14/02/2022 on the German Clinical Trials registry (DRKS) with the number DRKS00028079.

Differences in the thermal properties and surface temperature of prehospital antihypothermia devices: an in vitro study

BACKGROUND

Preventing and treating hypothermia in prehospital settings is crucial. Several products have been developed to prevent heat loss and actively warm patients in prehospital settings. We compared the efficacy and the surface temperature of different antihypothermia products, using a fluid-based model at two ambient temperatures.

METHODS

We tested five active (Blizzard Heat with active pads, Ready-Heat, Ready-Heat-II, Hypothermia Prevention and Management Kit (HPMK), Bair Hugger) and five passive (Blizzard Heat, Heat Reflective Shell, sleeping bag, 'space blanket', wool blanket) antihypothermia products. A torso model consisting of four 8 L bags of fluid preheated to 36°C±0.5°C (97±0.5°F) was used to compare the devices' performances at 20°C (68°F) and 8°C (46°F). Inner and surface temperatures were recorded for up to 480 min.

RESULTS

We found significant differences in heat loss in fluid bags among the tested devices at both temperatures (p<0.001). At 20°C, only HPMK and Ready-Heat-II increased the inner temperature for 480 min while Blizzard Heat with active pads prevented heat loss. Ready-Heat prevented heat loss for 90 min. All the other devices did not prevent heat loss beyond 30 min. At 8°C, none of the products heated the model. Bair Hugger, HPMK, Ready-Heat II and sleeping bag prevented heat loss for 30 min. At 60, 90 and 120 min HPMK, Ready-Heat II and Bair Hugger were the most effective. Over 480 min, Bair Hugger was most effective, with a heat loss of 2.3°C±0.4°C. The surface temperature exceeded 44°C (111°F) for all the exothermic warming devices when used for a prolonged period of time.

CONCLUSION

At 20°C, HPMK and Ready-Heat-II increased fluid temperature in the model, while the other devices decreased heat loss. At 8°C, none of the tested devices increased the temperature. However, active heating devices prevented heat loss slightly better than passive methods. A protective insulation layer should be used with all active heating blankets.

Continued Relevance of Initial Temperature Measurement in Trauma Patients

OBJECTIVES

Hypothermia occurs in 30-50% of severely injured trauma patients and is associated with multiple metabolic derangements and worsened outcomes. However, hypothermia continues to be under-diagnosed which leads to inadequate triage and treatment in trauma patients. Our study set out to determine if hypothermia is an independent predictor of mortality in trauma patients.

METHODS

We retrospectively reviewed data of all trauma activation patients over a 5-year period. Data were collected on patient demographics, initial core temperature, Glasgow Coma Scale (GCS) on presentation, and injury severity score (ISS). Patients were then stratified into groups based on presenting temperature, ISS, and GCS. Outcomes compared were mortality, blood products received, and intensive care unit (ICU) length of stay. Correlations and logistic regression were used to test the hypotheses.

RESULTS

Survival and temperature data were reviewed on 15,567 patients. Initial temperature was not significantly associated with ICU length of stay or blood products transfused (P = .21 and P = .08, respectively). However, odds ratio of mortality in hypothermic patients (<35°C) compared to normothermic patients (35-39°C) was 3.95 (95% CI 2.90-5.41). When controlling for GCS and ISS, separately, temperature remained an independent predictor of mortality.

CONCLUSIONS

Hypothermia is an independent risk factor for mortality in trauma patients. It remains crucial to obtain accurate presenting temperatures in trauma patients in order to triage and treat hypothermia. Based on our data, obtaining core temperatures and rapidly treating hypothermia continues to be a vital part of the secondary survey of trauma patients.

Evaluating the Tactical Combat Casualty Care principles in civilian and military settings: systematic review, knowledge gap analysis and recommendations for future research

OBJECTIVES

The Tactical Combat Casualty Care (TCCC) guidelines detail resuscitation practices in prehospital and austere environments. We sought to review the content and quality of the current TCCC and civilian prehospital literature and characterize knowledge gaps to offer recommendations for future research.

METHODS

MEDLINE, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials were searched for studies assessing intervention techniques and devices used in civilian and military prehospital settings that could be applied to TCCC guidelines. Screening and data extraction were performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Quality appraisal was conducted using appropriate tools.

RESULTS

Ninety-two percent (n=57) of studies were observational. Most randomized trials had low risk of bias, whereas observational studies had higher risk of bias. Interventions of massive hemorrhage control (n=17) were wound dressings and tourniquets, suggesting effective hemodynamic control. Airway management interventions (n=7) had high success rates with improved outcomes. Interventions of respiratory management (n=12) reported low success with needle decompression. Studies assessing circulation (n=18) had higher quality of evidence and suggested improved outcomes with component hemostatic therapy. Hypothermia prevention interventions (n=2) were generally effective. Other studies identified assessed the use of extended focused assessment with sonography in trauma (n=3) and mixed interventions (n=2).

CONCLUSIONS

The evidence was largely non-randomized with heterogeneous populations, interventions, and outcomes, precluding robust conclusions in most subjects addressed in the review. Knowledge gaps identified included the use of blood products and concentrate of clotting factors in the prehospital setting.

LEVEL OF EVIDENCE

Systematic review, level III.

On-Site Medical Management of Avalanche Victims-A Narrative Review

Avalanche accidents are common in mountain regions and approximately 100 fatalities are counted in Europe each year. The average mortality rate is about 25% and survival chances are mainly determined by the degree and duration of avalanche burial, the patency of the airway, the presence of an air pocket, snow characteristics, and the severity of traumatic injuries. The most common cause of death in completely buried avalanche victims is asphyxia followed by trauma. Hypothermia accounts for a minority of deaths; however, hypothermic cardiac arrest has a favorable prognosis and prolonged resuscitation and extracorporeal rewarming are indicated. In this article, we give an overview on the pathophysiology and on-site management of avalanche victims.

Trauma Prehospital Hypothermia Prevention and Treatment: An Observational Study

BACKGROUND

Hypothermia in trauma patients causes increased morbidity and mortality. Swift recognition and treatment are important to prevent any further heat loss. In addition, patient discomfort from cold decreases satisfaction with care. The administration of active and passive rewarming measures is important in the prevention and treatment of hypothermia, but their use in prehospital trauma patients in Portugal has not been previously reported.

OBJECTIVE

To assess the prevalence of hypothermia, the impact of rewarming measures, and the management of the discomfort caused by cold.

METHODS

This is a prospective cohort study conducted in Immediate Life Support Ambulances in Portugal between March 1, 2019, and April 30, 2020.

RESULTS

This study included records of 586 trauma patients; of whom, 66.2% were men. Cranioencephalic trauma was the most common trauma observed, followed by lower limb and thoracic traumas. Mean body temperature increased 0.12 °C between the first and last assessments (p < .05). Most patients experiencing a level of discomfort of 5 or more on a 0-10 scale reported improvement (from 17.2% to 2.4% after nurses' intervention). Warmed intravenous fluids proved to be effective (p < .05) in increasing body temperature, and passive rewarming measures were effective in preventing hypothermia.

CONCLUSIONS

Hypothermia management has to consider the initial temperature, the season, the available rewarming measures, and the objectives to be achieved. The optimization of resources for the monitoring and treatment of hypothermia should be a priority in prehospital assistance. The implementation of rewarming measures improves patients' outcomes and decreases the discomfort caused by cold in prehospital care.

Water Temperature Variability Is Associated with Neurologic Outcomes in Out-of-Hospital Cardiac Arrest Survivors Who Underwent Targeted Temperature Management at 33°C

We examined the association between variability in body temperature (BT) and water temperature (WT) during the maintenance period of targeted temperature management (TTM) and neurologic outcomes in out-of-hospital cardiac arrest (OHCA) survivors. Adult (≥18 years), comatose OHCA survivors who underwent TTM at 33°C between October 2015 and December 2019 were included. We collected data on BT and WT recorded every minute during the TTM maintenance period. Temperature variability was measured as the standard deviation of BT and WT during the 33°C maintenance period. The primary outcome was a poor neurologic outcome, defined as a cerebral performance category scale 3-5 at 6 months. Of the 154 included patients, 96 (62.3%) had poor outcomes. The BT variability in the poor outcome group was lower than that in the good outcome group (0.16°C [0.13-0.27°C] vs. 0.13°C [0.11-0.18°C]). In addition, the WT variability during the maintenance period in the poor outcome group was lower than that in the good outcome group (2.24°C [1.80-3.96°C] vs. 1.77°C [1.26-2.32°C]). In the multivariate analysis, WT variability (odds ratio 0.508; 95% confidence interval, 0.295-0.874; p = 0.014) was independently associated with poor neurologic outcome. BT variability and cooling beyond 33.0°C ± 1.0°C were not associated with poor neurologic outcomes. WT variability during the maintenance period was independently associated with neurologic outcomes in OHCA survivors who underwent TTM at 33°C. In addition, overcooling or undercooling during the maintenance period was not associated with neurologic outcomes.

[Cardiac arrest under special circumstances]

These guidelines of the European Resuscitation Council (ERC) Cardiac Arrest under Special Circumstances are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required for basic and advanced life support for the prevention and treatment of cardiac arrest under special circumstances; in particular, specific causes (hypoxia, trauma, anaphylaxis, sepsis, hypo-/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), specific settings (operating room, cardiac surgery, cardiac catheterization laboratory, dialysis unit, dental clinics, transportation [in-flight, cruise ships], sport, drowning, mass casualty incidents), and specific patient groups (asthma and chronic obstructive pulmonary disease, neurological disease, morbid obesity, pregnancy).

Randomised controlled trials in pre-hospital trauma: a systematic mapping review

BACKGROUND

Trauma is a leading cause of morbidity and mortality worldwide with about 5.8 million deaths globally and the leading cause of death in those aged 45 and younger. The pre-hospital phase of traumatic injury is particularly important as care received during this phase has effects on survival. The need for high quality clinical trials in this area has been recognised for several years as a key priority to improve the evidence base and, ultimately, clinical care in prehospital trauma. We aimed to systematically map the existing evidence base for pre-hospital trauma trials, to identify knowledge gaps and inform decisions about the future research agenda.

METHODS

A systematic mapping review was conducted first employing a search of key databases (MEDLINE, CINAHL, EMBASE, and Cochrane Library from inception to March 23rd 2020) to identify randomised controlled trials within the pre-hospital trauma and injury setting. The evidence 'map' identified and described the characteristics of included studies and compared these studies against existing priorities for research. Narrative description of studies informed by analysis of relevant data using descriptive statistics was completed.

RESULTS

Twenty-three eligible studies, including 10,405 participants across 14 countries, were identified and included in the systematic map. No clear temporal or geographical trends in publications were identified. Studies were categorised into six broad categories based on intervention type with evaluations of fluid therapy and analgesia making up 60% of the included trials. Overall, studies were heterogenous with regard to individual interventions within categories and outcomes reported. There was poor reporting across several studies. No studies reported patient involvement in the design or conduct of the trials.

CONCLUSION

This mapping review has highlighted that evidence from trials in prehospital trauma is sparse and where trials have been completed, the reporting is generally poor and study designs sub-optimal. There is a continued need, and significant scope, for improvement in a setting where high quality evidence has great potential to make a demonstrable impact on care and outcomes.

European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances

These European Resuscitation Council (ERC) Cardiac Arrest in Special Circumstances guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required to basic and advanced life support for the prevention and treatment of cardiac arrest in special circumstances; specifically special causes (hypoxia, trauma, anaphylaxis, sepsis, hypo/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), special settings (operating room, cardiac surgery, catheter laboratory, dialysis unit, dental clinics, transportation (in-flight, cruise ships), sport, drowning, mass casualty incidents), and special patient groups (asthma and COPD, neurological disease, obesity, pregnancy).

Prevention of hypothermia in trauma victims - the HYPOTRAUM 2 study

INTRODUCTION

Hypothermia is common in trauma patients. It contributes to increasing mortality rate. Hypothermia is multifactorial, favoured by exposure to cold, severity of the patient's state and interventions such as infusion of fluids at room temperature.

AIM

To demonstrate that specific management of hypothermia (or of the risk of hypothermia) increases the number of trauma patients arriving at the hospital with a temperature >35°C.

DESIGN

This is a prospective, multicentre, open-label, pragmatic, cluster randomized clinical trial of an expected 1,200 trauma patients included by 12 out-of-hospital mobile intensive care units (MICU). Trauma patients are included in a prehospital setting if they present at least one of the following criteria known to be associated with an increased incidence of hypothermia: ambient temperature <18°C, Glasgow coma scale <15, systolic arterial blood pressure <100 mm Hg or body temperature <35°C. Patients are randomized, by cluster, to receive a conventional management or 'interventional' nursing management associating: continuous epitympanic temperature monitoring, early installation in the heated ambulance (temperature target >30°C controlled by infrared thermometer), protection by a survival blanket, and use of heated solutes (temperature objective >35°C controlled by infrared thermometer). The primary end point is the prevalence of hypothermia on arrival at the hospital. The hypothesis tested is a reduction from 20% to 13% in the prevalence of hypothermia. Secondary end points are to evaluate the interaction between the effectiveness of the measures taken and: (1) the severity of the patients assessed by the Revised Trauma Score; (2) the meteorological conditions when they are managed; (3) the time of care; and (4) therapeutic interventions.

DISCUSSION

This trial will assess the effectiveness of an invasive, out-of-hospital, temperature management on the onset of hypothermia in moderate to severe trauma patients.

IMPACT

Specific management of hypothermia is expected to decrease hypothermia in trauma patients.

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.

Cold weather is independently associated with hypothermia in severely injured trauma patients

Introduction

Hypothermia at admission in trauma patients has been significantly associated with worse outcomes and increased blood usage. Previous studies have found variably significant associations between ambient temperatures and incidence of hypothermia in trauma patients.

Methods

The trauma quality improvement registry was queried for data on trauma patients admitted direct from the scene over a 5-year period. This database was matched to daily weather data taken from the nearest National Oceanic and Atmospheric Administration land-based climate monitoring center, and further combined with blood usage data from the laboratory information system.

Results

Multivariate logistic regression models predicted significant associations between ambient temperature and patient admission temperature for severely injured patients. No significant direct associations were predicted between ambient temperature and in-hospital mortality or blood usage. Models predicted a significant association between decreased admission temperature and increased likelihood of both blood transfusion and mortality for a severely injured subgroup.

Conclusions

Ambient temperature is a significant contributor to the rate of admission hypothermia in trauma patients. Most of the variability in admission temperatures for severely injured trauma patients remains unaccounted for by models using standard markers of anatomic and physiologic severity. Decreasing admission temperature is significantly associated with increased mortality and likelihood of blood transfusion for severely injured patients.

Cardiac Arrest Secondary to Accidental Hypothermia: Rewarming Strategies in the Field

Hypothermic cardiac arrest is rare and poses a challenge to prehospital responders. Standard cardiac arrest protocols advise treating reversible causes of arrest; however, rewarming the cold casualty is not easily achieved in the field. This article aimed to review the literature on hypothermia in order to produce evidence-based recommendations on rewarming that could realistically be applied to hypothermic cardiac arrest patients.

Wilderness Medical Society Clinical Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2019 Update

To provide guidance to clinicians, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and a balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations. This is the 2019 update of the Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2014 Update.

A regional massive hemorrhage protocol developed through a modified Delphi technique

BACKGROUND

A massive hemorrhage protocol (MHP) enables rapid delivery of blood components in a patient who is exsanguinating pending definitive hemorrhage control, but there is variability in MHP implementation rates, content and compliance owing to challenges presented by infrequent activation, variable team performance and patient acuity. The goal of this project was to identify the key evidence-based principles and quality indicators required to develop a standardized regional MHP.

METHODS

A modified Delphi consensus technique was performed in the spring and summer of 2018. Panellists used survey links to independently review and rate (on a 7-point Likert scale) 43 statements and 8 quality indicators drafted by a steering committee composed of transfusion medicine specialists and technologists, and trauma physicians. External stakeholder input from all hospitals in Ontario was sought.

RESULTS

Three rounds were held with 36 experts from diverse clinical backgrounds. Consensus was reached for 42 statements and 8 quality indicators. Additional modifications from external stakeholders were incorporated to form the foundation for the proposed MHP.

INTERPRETATION

This MHP template will provide the basis for the design of an MHP toolkit, including specific recommendations for pediatric and obstetrical patients, and for hospitals with limited availability of blood components or means to achieve definitive hemorrhage control. We believe that harmonization of MHPs in our region will simplify training, increase uptake of evidence-based interventions, enhance communication, improve patient comfort and safety, and, ultimately, improve patient outcomes.

Successful Field Rewarming of a Patient with Apparent Moderate Hypothermia Using a Hypothermia Wrap and a Chemical Heat Blanket

Hypothermia is a common problem encountered by search and rescue teams. Although mildly hypothermic patients can be rewarmed in the field and can then self-evacuate, the Wilderness Medical Society hypothermia guidelines suggest that a moderately hypothermic patient in the wilderness requires warming in a medical facility. The hypothermia prevention and management kit, developed by the US military, consists of a chemical heat blanket (CHB) and a heat-reflective shell. We present a case in which a hypothermia wrap and the CHB from a hypothermia prevention and management kit were used successfully to rewarm a patient with apparent moderate hypothermia in the field. We are unaware of previous reports of successful field rewarming of a patient with moderate hypothermia. We believe the use of the CHB in conjunction with a hypothermia wrap made field rewarming possible. We recommend that a CHB, along with the components of a hypothermia wrap, be carried by search and rescue teams when a hypothermic patient might be encountered. Although there were no documented core temperatures, we believe this case is consistent with the hypothesis that if a hypothermic patient who is found lying down and shivering is allowed to stand or walk before insulation is applied and before there has been an additional period of 30 min during which the patient continues to shiver, there may be increased afterdrop with deleterious results.

Human Responses to 5 Heated Hypothermia Wrap Systems in a Cold Environment

INTRODUCTION

We compared the effectiveness of 5 heated hypothermia wrap systems.

METHODS

Physiologic and subjective responses were determined in 5 normothermic subjects (1 female) for 5 heated hypothermia wraps (with vapor barrier and chemical heat sources) during 60 min of exposure to a temperature of -22°C. The 5 systems were 1) user-assembled; 2) Doctor Down Rescue Wrap; 3) hypothermia prevention and management kit (HPMK); 4) MARSARS Hypothermia Stabilizer Bag; and 5) Wiggy's Victims Casualty Hypothermia Bag. Core and skin temperature, metabolic heat production, skin heat loss, and body net heat gain were determined. Subjective responses were also evaluated for whole body cold discomfort, overall shivering rating, overall temperature rating, and preferential ranking.

RESULTS

The Doctor Down and user-assembled systems were generally more effective, with higher skin temperatures and lower metabolic heat production; they allowed less heat loss, resulting in higher net heat gain (P<0.05). HPMK had the lowest skin temperature and highest shivering heat production and scored worse than the other 4 systems for the "whole body cold discomfort" and "overall temperature" ratings (P<0.05).

CONCLUSIONS

The user-assembled and Doctor Down systems were most effective, and subjects were coldest with the HPMK system. However, it is likely that any of the tested systems would be viable options for wilderness responders, and the choice would depend on considerations of cost; volume, as it relates to available space; and weight, as it relates to ability to carry or transport the system to the patient.

Predictors of Hypothermia upon Trauma Center Arrival in Severe Trauma Patients Transported to Hospital via EMS

Introduction: Hypothermia in severe trauma patients can increase mortality by 25%. Active warming practices decrease mortality and are recommended in the Advanced Trauma Life Support (ATLS) guidelines. Despite this, many emergency medical services (EMS) vehicles do not carry equipment necessary to perform active warming. The intent of this study was to determine the rate of hypothermia in severe trauma patients upon major trauma center (MTC) arrival, as well as to characterize factors associated with hypothermia in trauma in order to devote potential resources to those at highest risk. Methods: This single-center retrospective chart review included adults (age ≥ 18) in the local trauma registry (trauma team activation or injury severity score ≥12) from January 2009 to June 2016. Logistic regression was used to identify predictors of hypothermia on MTC arrival. Results: A total of 3,070 patient charts were reviewed, of which 159 (5.2%) were hypothermic. Multivariate logistic regression identified 7 factors that were significantly associated with hypothermia on MTC arrival in severe trauma. Risk factors for hypothermia on MTC arrival after severe trauma included: intubation pre-MTC, increased number of co-morbidities, and increased injury severity. Conversely, protective factors against hypothermia were: higher initial systolic blood pressure (SBP), penetrating injury, referral to MTC, and higher ambient outdoor temperatures. Median length of stay in hospital was 7 days for hypothermic patients compared to 4 days for normothermic patients (Δ 3 days; p < 0.001). Only 69.2% of hypothermic patients survived to discharge compared to 93.9% of normothermic patients (Δ 24.7%; χ² = 133.4, p < 0.001). Conclusions: This retrospective study of hypothermia in major trauma patients found a rate of hypothermia of 5%. Factors associated with higher risk of hypothermia include pre-MTC intubation, high ISS, multiple comorbidities, low SBP, non-penetrating mechanism of injury, and being transferred directly to MTC, and colder outdoor temperature. Avoidance of hypothermia is imperative to the management of major trauma patients. Prospective studies are required to determine if prehospital warming in these high-risk patients decreases the rate of hypothermia in major trauma and improves patient outcomes.

Management of accidental hypothermia: A narrative review

A narrative review is presented on the diagnosis, treatment and management of accidental hypothermia. Although all these processes form a continuum, for descriptive purposes in this manuscript the recommendations are organized into the prehospital and in-hospital settings. At prehospital level, it is advised to: a) perform high-quality cardiopulmonary resuscitation for cardiac arrest patients, regardless of body temperature; b) establish measures to minimize further cooling; c) initiate rewarming; d) prevent rescue collapse and continued cooling (afterdrop); and (e) select the appropriate hospital based on the clinical and hemodynamic situation of the patient. Extracorporeal life support has revolutionized rewarming of the hemodynamically unstable victim or patients suffering cardiac arrest, with survival rates of up to 100%. The new evidences indicate that the management of accidental hypothermia has evolved favorably, with substantial improvement of the final outcomes.

Use of an intravascular temperature control catheter for rewarming of hypothermic trauma patients with ongoing hemorrhagic shock after combined damage control thoracotomy and laparotomy: A case series

BACKGROUND

Correction of hypothermia is a key component of the resuscitation of critically injured patients with hemorrhagic shock who require damage control surgery. External rewarming methods may not be sufficient in this population, while extracorporeal techniques lack widespread feasibility. Intravascular catheter-based temperature modulation is increasingly being employed in different critically ill patient populations but has not been described as part of a damage control resuscitation strategy in trauma patients.

METHODS

We retrospectively reviewed the medical records of all patients admitted to our multi-trauma intensive care unit from July 1, 2015 - December 31, 2017 in whom an intravascular temperature control catheter (IVTCC) was employed for rewarming from hypothermia during the immediate postoperative resuscitation of continued hemorrhage after undergoing combined damage control thoracotomy and laparotomy for trauma. All patients received baseline treatment with active external rewarming modalities and inline fluid/blood warmers. Core temperature values over the first 24 h of hospital admission were analyzed. Efficacy (rewarming rate) and safety (associated adverse events) of the IVTCC system were determined.

RESULTS

Three patients (age 22 ± 4.6, 100% male, 100% torso gunshot wounds with prehospital cardiac arrest) meeting the inclusion criteria were treated with the IVTCC system during the study period. Temperature at the start of rewarming using the IVTCC ranged from 30.1 to 35.5 °C. Despite ongoing severe hemorrhagic shock (24-hour ICU blood product requirement: 104 ± 44 units), a mean rewarming rate of 1.04 ± 0.63°C/hour was achieved. One patient suffered an uncomplicated catheter-associated deep vein thrombosis. Two of the 3 patients survived to hospital discharge with intact cognitive function.

CONCLUSIONS

Use of an IVTCC may be a minimally-invasive, practical, and effective method for rewarming critically ill trauma patients with ongoing hemorrhagic shock after multi-cavitary damage control surgery. Further studies are needed to compare this technology with currently available rewarming methods.

Managing accidental hypothermia: a UK-wide survey of prehospital and search and rescue providers

AIM

The management of hypothermic casualties is a challenge faced by all prehospital and search and rescue (SAR) teams. It is not known how the practice of these diverse teams compare. The aim of this study was to review prehospital hypothermia management across a wide range of SAR providers in the UK.

METHODS

A survey of ground ambulances (GAs), air ambulances (AAs), mountain rescue teams (MRTs, including Ministry of Defence), lowland rescue teams (LRTs), cave rescue teams (CRTs), and lifeboats and lifeguard organisations (LLOs) across the UK was conducted between May and November 2017. In total, 189 teams were contacted. Questions investigated packaging methods, temperature measurement and protocols for managing hypothermic casualties.

RESULTS

Response rate was 59%, comprising 112 teams from a wide range of organisations. Heavyweight (>3 kg) casualty bags were used by all CRTs, 81% of MRTs, 29% of LRTs, 18% of AAs and 8% of LLOs. Specially designed lightweight (<0.5 kg) blankets or wraps were used by 93% of LRTs, 85% of LLOs, 82% of GAs, 71% of AAs and 50% of MRTs. Bubble wrap was used mainly by AAs, with 35% of AAs reporting its use. Overall, 94% of packaging methods incorporated both insulating and vapour-tight layers. Active warming by heated pads or blankets was used by 65% of AAs, 60% of CRTs, 54% of MRTs, 29% of LRTs and 9% of GAs, with no LLO use. Temperature measurement was reported by all AAs and GAs, 93% of LRTs, 80% of CRTs, 75% of MRTs and 31% of LLOs. The favoured anatomical site for temperature measurement was tympanic. Protocols for packaging hypothermic casualties were reported by 73% of services.

CONCLUSIONS

This survey describes current practice in prehospital hypothermia management, comparing the various methods used by different teams, and provides a basis to direct further education and research.

A cool response-The influence of ambient temperature on capillary refill time

OBJECTIVE

To describe the effect of low ambient temperature on skin temperature and capillary refill (CR) time in forehead, sternum and finger pulp.

METHODS

An observational, nonrandomized experimental study on 15 healthy subjects (6 females) in a cold room (8°C). Outcome measures were skin temperature and quantified CR test after application of a standardized blanching pressure (9 N/cm² ) using digital photographic polarization spectroscopy to generate CR times.

RESULTS

The finger pulp showed marked temperature fall and prolonged CR times (>10 seconds). The CR registrations of the forehead and sternum were more comparable to curves observed in a control material at room temperature, and skin temperature falls were less marked. CR times were not prolonged in forehead measurements. At the sternum, some individuals showed CR times beyond guideline recommendations despite only a marginal reduction in skin temperature.

CONCLUSIONS

Low ambient temperature is a strong independent factor for CR time at peripheral sites. Reservation about sternum as a site of measurement is warranted since cold provocation produced prolonged CR times in some individuals. We found that the forehead is the most thermostable of the 3 sites and thus the preferred site to avoid ambient temperature artifact in measuring CR time.

International Commission for Mountain Emergency Medicine Consensus Guidelines for On-Site Management and Transport of Patients in Canyoning Incidents

Canyoning is a recreational activity that has increased in popularity in the last decade in Europe and North America, resulting in up to 40% of the total search and rescue costs in some geographic locations. The International Commission for Mountain Emergency Medicine convened an expert panel to develop recommendations for on-site management and transport of patients in canyoning incidents. The goal of the current review is to provide guidance to healthcare providers and canyoning rescue professionals about best practices for rescue and medical treatment through the evaluation of the existing best evidence, focusing on the unique combination of remoteness, water exposure, limited on-site patient management options, and technically challenging terrain. Recommendations are graded on the basis of quality of supporting evidence according to the classification scheme of the American College of Chest Physicians.

Protection against cold - a survey of available equipment in Swedish pre-hospital services

BACKGROUND

The aim of this study was to survey the current equipment used for prevention, treatment and monitoring of accidental hypothermia in Swedish pre-hospital services.

METHODS

A questionnaire was sent to all road ambulance services (AS), the helicopter emergency medical services (HEMS), the national helicopter search and rescue service (SAR) and the municipal rescue services (RS) in Sweden to determine the availability of insulation, active warming, fluid heating, and low-reading thermometers.

RESULTS

The response rate was 77% (n = 255). All units carried woollen or polyester blankets for basic insulation. Specific windproof insulation materials were common in the HEMS, SAR and RS units but only present in about half of the AS units. Active warming equipment was present in all the SAR units, but only in about two-thirds of the HEMS units and about one-third of the AS units. About half of the RS units had the ability to provide a heated tent or container. Low-reading thermometers were present in less than half of the AS and HEMS units and were non-existent in the SAR units. Pre-warmed intravenous fluids were carried by almost all of the AS units and half of the HEMS units but infusion heaters were absent in most units.

CONCLUSION

Basic insulation capabilities are well established in the Swedish pre-hospital services. Specific wind and waterproof insulation materials, active warming devices, low-reading thermometers and IV fluid heating systems are less common. We suggest the development and implementation of national guidelines on accidental hypothermia that include basic recommendations on equipment requirements.

The opinions of ambulance personnel regarding using a heated mattress for patients being cared for in a cold climate - An intervention study in ambulance care

The purpose of the study was to describe the opinions of ambulance personnel regarding differences between using a heated mattress and a standard ambulance mattress. This study was an intervention study with pre- and post-evaluation. Evaluations of the opinions of personnel regarding the standard unheated mattress were conducted initially. After the intervention with new heated mattresses, follow-up evaluations were conducted. Ambulance personnel (n=64) from an ambulance station in northern Sweden took part in the study, which ran from October 2014 until February 2016. There were differences in opinions regarding the standard unheated mattress and the new heated mattress. The evaluation of the proxy ratings by the personnel showed that the heated mattress was warmer than the standard mattress, more pleasant to lie on and that patients were happier and more relaxed than when the standard mattress was used. The ambulance personnel in this study rated the experience of working with the heated mattress as very positive and proxy rated that it had a good effect on patient comfort. A heated mattress can be recommended for patients in ambulance care, even if more research is needed to receive sufficient evidence.

Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

BACKGROUND

This paper provides an up-to-date review of the management and outcome of accidental hypothermia patients with and without cardiac arrest.

METHODS

The authors reviewed the relevant literature in their specialist field. Summaries were merged, discussed and approved to produce this narrative review.

RESULTS

The hospital use of minimally-invasive rewarming for non-arrested, otherwise healthy, patients with primary hypothermia and stable vital signs has the potential to substantially decrease morbidity and mortality for these patients. Extracorporeal life support (ECLS) has revolutionised the management of hypothermic cardiac arrest, with survival rates approaching 100 % in some cases. Hypothermic patients with risk factors for imminent cardiac arrest (temperature <28 °C, ventricular arrhythmia, systolic blood pressure <90 mmHg), and those who have already arrested, should be transferred directly to an ECLS-centre. Cardiac arrest patients should receive continuous cardiopulmonary resuscitation (CPR) during transfer. If prolonged transport is required or terrain is difficult, mechanical CPR can be helpful. Delayed or intermittent CPR may be appropriate in hypothermic arrest when continuous CPR is impossible. Modern post-resuscitation care should be implemented following hypothermic arrest. Structured protocols should be in place to optimise pre-hospital triage, transport and treatment as well as in-hospital management, including detailed criteria and protocols for the use of ECLS and post-resuscitation care.

CONCLUSIONS

Based on new evidence, additional clinical experience and clearer management guidelines and documentation, the treatment of accidental hypothermia has been refined. ECLS has substantially improved survival and is the treatment of choice in the patient with unstable circulation or cardiac arrest.

A prospective observational study of the association between cabin and outside air temperature, and patient temperature gradient during helicopter transport in New South Wales

The prevalence of hypothermia in patients following helicopter transport varies widely. Low outside air temperature has been identified as a risk factor. Modern helicopters are insulated and have heating; therefore outside temperature may be unimportant if cabin heat is maintained. We sought to describe the association between outside air, cabin and patient temperature, and having the cabin temperature in the thermoneutral zone (18-36°C) in our helicopter-transported patients. We conducted a prospective observational study over one year. Patient temperature was measured on loading and engines off. Cabin and outside air temperature were recorded for the same time periods for each patient, as well as in-flight. Previously identified risk factors were recorded. Complete data was obtained for 133 patients. Patients' temperature increased by a median of 0.15°C (P=0.013). There was no association between outside air temperature or cabin temperature and patient temperature gradient. The best predictor of patient temperature on landing was patient temperature on loading (R2=0.86) and was not improved significantly when other risk factors were added (P=0.63). Thirty-five percent of patients were hypothermic on loading, including those transferred from district hospitals. No patient loaded normothermic became hypothermic when the cabin temperature was in the thermoneutral zone (P=0.04). A large proportion of patients in our sample were hypothermic at the referring hospital. The best predictor of patient temperature on landing is patient temperature on loading. This has implications for studies that fail to account for pre-flight temperature.

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.

Effect evaluation of a heated ambulance mattress-prototype on thermal comfort and patients' temperatures in prehospital emergency care--an intervention study

Background

The ambulance milieu does not offer good thermal comfort to patients during the cold Swedish winters. Patients’ exposure to cold temperatures combined with a cold ambulance mattress seems to be the major factor leading to an overall sensation of discomfort. There is little research on the effect of active heat delivered from underneath in ambulance care. Therefore, the aim of this study was to evaluate the effect of an electrically heated ambulance mattress-prototype on thermal comfort and patients’ temperatures in the prehospital emergency care.

Methods

A quantitative intervention study on ambulance care was conducted in the north of Sweden. The ambulance used for the intervention group (n=30) was equipped with an electrically heated mattress on the regular ambulance stretcher whereas for the control group (n=30) no active heat was provided on the stretcher. Outcome variables were measured as thermal comfort on the Cold Discomfort Scale (CDS), subjective comments on cold experiences, and finger, ear and air temperatures.

Results

Thermal comfort, measured by CDS, improved during the ambulance transport to the emergency department in the intervention group (p=0.001) but decreased in the control group (p=0.014). A significant higher proportion (57%) of the control group rated the stretcher as cold to lie down compared to the intervention group (3%, p<0.001). At arrival, finger, ear and compartment air temperature showed no statistical significant difference between groups. Mean transport time was approximately 15 minutes.

Conclusions

The use of active heat from underneath increases the patients’ thermal comfort and may prevent the negative consequences of cold stress.

Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia: 2014 update

To provide guidance to clinicians, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations. This is an updated version of the original Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia published in Wilderness & Environmental Medicine 2014;25(4):425-445.

Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia

To provide guidance to clinicians, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations.

Effect evaluation of a heated ambulance mattress-prototype on body temperatures and thermal comfort--an experimental study

Background

Exposure to cold temperatures is, often, a neglected problem in prehospital care. One of the leading influences of the overall sensation of cold discomfort is the cooling of the back. The aim of this study was to evaluate the effect of a heated ambulance mattress-prototype on body temperatures and thermal comfort in an experimental study.

Method

Data were collected during four days in November, 2011 inside and outside of a cold chamber. All participants (n = 23) participated in two trials each. In one trial, they were lying on a stretcher with a supplied heated mattress and in the other trial without a heated mattress. Outcomes were back temperature, finger temperature, core body temperature, Cold Discomfort Scale (CDS), four statements from the state-trait anxiety – inventory (STAI), and short notes of their experiences of the two mattresses. Data were analysed both quantitatively and qualitatively. A repeated measure design was used to evaluate the effect of the two mattresses.

Results

A statistical difference between the regular mattress and the heated mattress was found in the back temperature. In the heated mattress trial, the statement “I am tense” was fewer whereas the statements “I feel comfortable”, “I am relaxed” and “I feel content” were higher in the heated mattress trial. The qualitative analyses of the short notes showed that the heated mattress, when compared to the unheated mattress, was experienced as warm, comfortable, providing security and was easier to relax on.

Conclusions

Heat supply from underneath the body results in increased comfort and may prevent hypothermia which is important for injured and sick patients in ambulance care.

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.

Prehospital risk factors of mortality and impaired consciousness after severe traumatic brain injury: an epidemiological study

Background

Severe traumatic brain injury (TBI) is a significant health concern and a major burden for society. The period between trauma event and hospital admission in an emergency department (ED) could be a determinant for secondary brain injury and early survival. The aim was to investigate the relationship between prehospital factors associated with secondary brain injury (arterial hypotension, hypoxemia, hypothermia) and the outcomes of mortality and impaired consciousness of survivors at 14 days.

Methods

A multicenter, prospective cohort study was performed in dedicated trauma centres of Switzerland. Adults with severe TBI (Abbreviated Injury Scale score of head region (HAIS) >3) were included. Main outcome measures were death and impaired consciousness (Glasgow Coma Scale (GCS) ≤13) at 14 days. The associations between risk factors and outcome were assessed with univariate and multivariate regression models.

Results

589 patients were included, median age was 55 years (IQR 33, 70). The median GCS in ED was 4 (IQR 3-14), with abnormal pupil reaction in 167 patients (29.2%). Median ISS was 25 (IQR 21, 34). Three hundred seven patients sustained their TBI from falls (52.1%) and 190 from a road traffic accidents (32.3%). Median time from Out-of-hospital Emergency Medical Service (OHEMS) departure on scene to arrival in ED was 50 minutes (IQR 37-72); 451 patients had a direct admission (76.6%). Prehospital hypotension was observed in 24 (4.1%) patients, hypoxemia in 73 (12.6%) patients and hypothermia in 146 (24.8%). Prehospital hypotension and hypothermia (apart of age and trauma severity) was associated with mortality. Prehospital hypoxemia (apart of trauma severity) was associated with impaired consciousness; indirect admission was a protective factor.

Conclusion

Mortality and impaired consciousness at 14 days do not have the same prehospital risk factors; prehospital hypotension and hypothermia is associated with mortality, and prehospital hypoxemia with impaired consciousness.

Validity and reliability of the Cold Discomfort Scale: a subjective judgement scale for the assessment of patient thermal state in a cold environment

Complementary measures for the assessment of patient thermoregulatory state, such as subjective judgement scales, might be of considerable importance in field rescue scenarios where objective measures such as body core temperature, skin temperature, and oxygen consumption are difficult to obtain. The objective of this study was to evaluate, in healthy subjects, the reliability of the Cold Discomfort Scale (CDS), a subjective judgement scale for the assessment of patient thermal state in cold environments, defined as test–retest stability, and criterion validity, defined as the ability to detect a difference in cumulative cold stress over time. Twenty-two healthy subjects performed two consecutive trials (test–retest). Dressed in light clothing, the subjects remained in a climatic chamber set to −20 °C for 60 min. CDS ratings were obtained every 5 min. Reliability was analysed by test–retest stability using weighted kappa coefficient that was 0.84 including all the 5-min interval measurements. When analysed separately at each 5-min interval the weighted kappa coefficients were was 0.48–0.86. Criterion validity was analysed by comparing median CDS ratings of a moving time interval. The comparison revealed that CDS ratings were significantly increased for every interval of 10, 15, and 30 min (p < 0.001) but not for every interval of 5 min. In conclusion, in a prehospital scenario, subjective judgement scales might be a valuable measure for the assessment of patient thermal state. The results of this study indicated that, in concious patients, the CDS may be both reliable and valid for such purpose.

Equipment to prevent, diagnose, and treat hypothermia: a survey of Norwegian pre-hospital services

Introduction

Hypothermia is associated with increased morbidity and mortality in trauma patients and poses a challenge in pre-hospital treatment. The aim of this study was to identify equipment to prevent, diagnose, and treat hypothermia in Norwegian pre-hospital services.

Method

In the period of April-August 2011, we conducted a survey of 42 respondents representing a total of 543 pre-hospital units, which included all the national ground ambulance services, the fixed wing and helicopter air ambulance service, and the national search and rescue service. The survey explored available insulation materials, active warming devices, and the presence of protocols describing wrapping methods, temperature monitoring, and the use of warm i.v. fluids.

Results

Throughout the services, hospital duvets, cotton blankets and plastic “bubble-wrap” were the most common insulation materials. Active warming devices were to a small degree available in vehicle ambulances (14%) and the fixed wing ambulance service (44%) but were more common in the helicopter services (58-70%). Suitable thermometers for diagnosing hypothermia were lacking in the vehicle ambulance services (12%). Protocols describing how to insulate patients were present for 73% of vehicle ambulances and 70% of Search and Rescue helicopters. The minority of Helicopter Emergency Medical Services (42%) and Fixed Wing (22%) units was reported to have such protocols.

Conclusion

The most common equipment types to treat and prevent hypothermia in Norwegian pre-hospital services are duvets, plastic “bubble wrap”, and cotton blankets. Active external heating devices and suitable thermometers are not available in most vehicle ambulance units.