Predictors of cardiac arrest in severe accidental hypothermia

STUDY OBJECTIVE

To indicate predictors of witnessed hypothermic cardiac arrest.

METHODS

We conducted a retrospective analysis of 182 patients with severe accidental hypothermia (i.e., with core body temperature of ≤28 °C) who presented with preserved spontaneous circulation at first contact with medical services. We divided the study population into two groups: patients who suffered hypothermic cardiac arrest (HCA) at any time between encounter with medical service and restoration of normothermia, and those who did not sustain HCA. The analyzed outcome was the occurrence of cardiac arrest prior to achieving normothermia. Hemodynamic and biochemical parameters were analyzed with regard to their association with the outcome.

RESULTS

Fifty-two (29%) patients suffered HCA. In a univariable analysis, four variables were significantly associated with the outcome, namely heart rate (p < 0.001), systolic blood pressure (p = 0.03), ventricular arrhythmia (p = 0.001), and arterial oxygen partial pressure (p = 0.002). In the multivariable logistic regression the best model predicting HCA included heart rate, PaO2, and Base Excess (AUROC = 0.78). In prehospital settings, when blood gas analysis is not available, other multivariable model including heart rate and occurrence of ventricular arrhythmia (AUROC = 0.74) can be used. In this study population, threshold values of heart rate of 43/min, temperature-corrected PaO2 of 72 mmHg, and uncorrected PaO2 of 109 mmHg, presented satisfactory sensitivity and specificity for HCA prediction.

CONCLUSIONS

In patients with severe accidental hypothermia, the occurrence of HCA is associated with a lower heart rate, hypoxemia, ventricular arrhythmia, lower BE, and lower blood pressure. These parameters can be helpful in the early selection of high-risk patients and their allocation to extracorporeal rewarming facilities.

Establishing vitreous glucose and beta-hydroxybutyrate thresholds to assist in the diagnosis of hypothermia

The post-mortem diagnosis of hypothermia is challenging to establish due to the lack of pathognomonic findings and the confounding problem that any comorbidity may account for death. A 4-year retrospective case-control study was performed to compare the vitreous glucose and beta-hydroxybutyrate (BHB) concentrations between hypothermia deaths and controls. Over the study period 34 cases of hypothermia and 39 controls were analyzed. Hypothermia deaths versus controls had higher mean vitreous glucose (2.93 mmol/L vs. 1.14 mmol/L; p < 0.0001), BHB (1.89 mmol/L vs. 1.35 mmol/L; p = 0.01), and combined glucose+BHB (4.83 mmol/L vs. 2.46 mmol/L; p < 0.0001). Receiver operating characteristic (ROC) curves showed that the best model for predicting hypothermia in all cases was a combined vitreous glucose+BHB threshold of 2.03 mmol/L (sensitivity 88.2 %; specificity 56.4 %). A sub-group analysis broken down by detectable levels of blood ethanol showed that cases of hypothermia with and without ethanol maintained higher median vitreous glucose relative to the controls (2.05 vs. 0.35 mmol/L and 2.70 vs. 0.65 mmol/L; p = 0.02), however median BHB was only significantly elevated when ethanol was absent (1.88 vs. 1.42 mmol/L; p < 0.0001). Subsequent ROC curve analysis demonstrated that a better model for predicting hypothermia was in cases when blood ethanol was absent. In those deaths vitreous BHB alone had the best area under the curve, with an optimum threshold of 1.83 mmol/L (sensitivity 83.3 %; specificity 96.3 %). This study shows that post-mortem vitreous glucose and BHB are useful ancillary studies to assist in the diagnosis of hypothermia. Ethanol however is a confounder and can alter the utility of vitreous BHB when diagnosing hypothermia in those who have consumed alcohol prior to death.

Predicting Serious Bacterial Infections Among Hypothermic Infants in the Emergency Department

BACKGROUND

There is insufficient evidence to guide the initial evaluation of hypothermic infants. We aimed to evaluate risk factors for serious bacterial infections (SBI) among hypothermic infants presenting to the emergency department (ED).

METHODS

We conducted a multicenter case-control study among hypothermic (rectal temperature <36.5°C) infants ≤90 days presenting to the ED who had a blood culture collected. Our outcome was SBI (bacteremia, bacterial meningitis, and/or urinary tract infection). We performed 1:2 matching. Historical, physical examination and laboratory covariables were determined based on the literature review from febrile and hypothermic infants and used logistic regression to identify candidate risk factors.

RESULTS

Among 934 included infants, 57 (6.1%) had an SBI. In univariable analyses, the following were associated with SBI: age > 21 days, fever at home or in the ED, leukocytosis, elevated absolute neutrophil count, thrombocytosis, and abnormal urinalysis. Prematurity, respiratory distress, and hypothermia at home were negatively associated with SBI. The full multivariable model exhibited a c-index of 0.91 (95% confidence interval: 0.88-0.94). One variable (abnormal urinalysis) was selected for a reduced model, which had a c-index of 0.82 (95% confidence interval: 0.75-0.89). In a sensitivity analysis among hypothermic infants without fever (n = 22 with SBI among 116 infants), leukocytosis, absolute neutrophil count, and abnormal urinalysis were associated with SBI.

CONCLUSIONS

Historical, examination, and laboratory data show potential as variables for risk stratification of hypothermic infants with concern for SBI. Larger studies are needed to definitively risk stratify this cohort, particularly for invasive bacterial infections.

Accuracy of a zero-heat-flux thermometer in cardiac surgery, a prospective, multicentre, method comparison study

Accurate measurement of core temperature is of utmost importance during on-pump cardiac surgery, for detection of hypothermia before cardiopulmonary bypass (CPB), guidance of temperature management on CPB, active rewarming on CPB and guidance of warming therapy after CPB. Most temperature measurement methods are known to become inaccurate during rapid changes in core temperature and suffer from delayed detection of temperature changes. Zero-heat-flux temperature (ZHF) measurement from the lateral forehead may be an alternative, non-invasive method quantifying the core temperature. A prospective, observational, multicentre study was conducted in one hundred patients scheduled for on-pump coronary artery bypass grafting. Core temperatures were measured every minute by two zero-heat-flux thermometer (SpotOn™) and a bladder thermometer and a pulmonary artery catheter (PAC) in the period after induction of anesthesia until CPB. Accuracy and precision of both methods were compared against core temperature measured in the pulmonary artery using the method of Bland and Altman. A high accuracy (around 0.1 °C) and a very good precision (Limits of agreement (LoA) - 0.6; 0.4 °C) were found between zero-heat-flux thermometer and core temperature measured by PAC. Among the two ZHF thermometers the bias was negligible (- 0.003 °C) with narrow LoA of - 0.42 °C and 0.41 °C. In contrast, bias between bladder temperature and PAC temperature was large (0.51 °C) with corresponding LoA of - 0.06 °C and 1.1 °C. ZHF thermometers are in contrast to bladder temperature a reliable core temperature monitor in cardiac surgery during the period after induction of anestesia until CPB. The zero-heat-flux method can provide clinicians reliably with continuous and non-invasive measurements of core temperature in normothermic and mild hypothermic temperature ranges and therefore can be helpful to guide temperature management.

Candidate biomarkers in brown adipose tissue for post-mortem diagnosis of fatal hypothermia

Post-mortem diagnosis of fatal hypothermia (FHT) is challenging in forensic practice because traditional morphological and biochemical methods lack specificity. Recent studies have reported that brown adipose tissue (BAT) is activated during cold-induced non-shivering thermogenesis in mammals, but BAT has not been used to diagnose FHT. The aim of this study was to identify novel biomarkers in BAT for FHT based on morphological changes and differential protein expression. Two FHT animal models were created by exposing mice to 4 or -20 °C at 50% humidity. Morphologically, the unilocular lipid droplet content was significantly increased in BAT of FHT model mice compared with that of control mice. Proteomics analysis revealed a total of 283 and 266 differentially expressed proteins (DEPs) between the 4 or -20 °C FHT subgroups and control group, respectively. In addition, 140 proteins were shared between the FHT subgroups. GO and KEGG analyses revealed that the shared DEPs were mainly enriched in pathways associated with metabolism, oxidative phosphorylation, and thermogenesis. Further screening (|log2FC| > 1.6, q-value (FDR) < 0.05) identified GMFB, KDM1A, DDX6, RAB1B, SHMT-1, CLPTM1, and LMF1 as candidate biomarkers of FHT. Subsequent validation experiments were performed in FHT model mice using classic immunohistochemistry and western blotting. RAB1B and GMFB expression was further verified in BAT specimens from human cases of FHT. The results demonstrate that BAT can be used as a target organ for FHT diagnosis employing RAB1B and GMFB as biological markers, thus providing a new strategy for the post-mortem diagnosis of FHT in forensic practice.

Time to Positive Blood and Cerebrospinal Fluid Cultures in Hypothermic Young Infants

BACKGROUND AND OBJECTIVE

Hypothermia in young infants may be secondary to an invasive bacterial infection. No studies have explored culture time-to-positivity (TTP) in hypothermic infants. Our objective was to compare TTP of blood and cerebrospinal fluid (CSF) cultures between pathogenic and contaminant bacteria in hypothermic infants ≤90 days of age.

METHODS

Secondary analysis of a retrospective cohort of 9 children's hospitals. Infants ≤90 days of age presenting to the emergency department or inpatient setting with hypothermia from September 1, 2017, to May 5, 2021, with positive blood or CSF cultures were included. Differences in continuous variables between pathogenic and contaminant organism groups were tested using a 2-sample t test and 95% confidence intervals for the mean differences reported.

RESULTS

Seventy-seven infants met inclusion criteria. Seventy-one blood cultures were positive, with 20 (28.2%) treated as pathogenic organisms. Five (50%) of 10 positive CSF cultures were treated as pathogenic. The median (interquartile range [IQR]) TTP for pathogenic blood cultures was 16.8 (IQR 12.7-19.2) hours compared with 26.11 (IQR 20.5-48.1) hours for contaminant organisms (P < .001). The median TTP for pathogenic organisms on CSF cultures was 34.3 (IQR 2.0-53.7) hours, compared with 58.1 (IQR 52-72) hours for contaminant CSF organisms (P < .186).

CONCLUSIONS

Our study is the first to compare the TTP of blood and CSF cultures between pathogenic and contaminant bacteria in hypothermic infants. All pathogenic bacteria in the blood grew within 36 hours. No difference in TTP of CSF cultures between pathogenic and contaminant bacteria was detected.

[Hypothermia in elderly patients]

Hypothermia in older patients is a serious symptom, with high morbidity and mortality, and often an atypical presentation of an underlying problem. The most common causes are an infection and exposure to extreme cold ('accidental hypothermia'), but there are other, less common causes. These two cases show hypothermia as one of the symptoms in atypical presentations of underlying conditions. It is important to run diagnostics for infectious diseases and other underlying causes, and start antibiotics promptly. If there is no response to antibiotics and diagnostics do not reveal evidence of an infection, clinicians need to consider other causes of hypothermia.

Clinician Management Practices for Infants With Hypothermia in the Emergency Department

BACKGROUND

Young infants with serious bacterial infections (SBI) or herpes simplex virus (HSV) infections may present to the emergency department (ED) with hypothermia. We sought to evaluate clinician testing and treatment preferences for infants with hypothermia.

METHODS

We developed, piloted, and distributed a survey of ED clinicians from 32 US pediatric hospitals between December 2022 to March 2023. Survey questions were related to the management of infants (≤60 days of age) with hypothermia in the ED. Questions pertaining to testing and treatment preferences were stratified by age. We characterized clinician comfort with the management of infants with hypothermia.

RESULTS

Of 1935 surveys distributed, 1231 (63.6%) were completed. The most common definition of hypothermia was a temperature of ≤36.0°C. Most respondents (67.7%) could recall caring for at least 1 infant with hypothermia in the previous 6 months. Clinicians had lower confidence in caring for infants with hypothermia compared with infants with fever (P < .01). The proportion of clinicians who would obtain testing was high in infants 0 to 7 days of age (97.3% blood testing for SBI, 79.7% for any HSV testing), but declined for older infants (79.3% for blood testing for SBI and 9.5% for any HSV testing for infants 22-60 days old). A similar pattern was noted for respiratory viral testing, hospitalization, and antimicrobial administration.

CONCLUSIONS

Testing and treatment preferences for infants with hypothermia varied by age and frequently reflected observed practices for febrile infants. We identified patterns in management that may benefit from greater research and implementation efforts.

Accuracy of non-invasive sensors measuring core body temperature in cardiac surgery ICU patients - results from a monocentric prospective observational study

PURPOSE

Temperature monitoring in the perioperative setting often represents a compromise between accuracy, invasiveness of probe placement, and patient comfort. Transcutaneous sensors using the Zero-Heat-Flux (ZHF) and Double-Sensor (DS) technology have been developed and evaluated in a variety of clinical settings. The present study is the first to compare the performance of both sensors simultaneously with temperature measured by a Swan-Ganz catheter (PAC) in patients admitted to the intensive care unit (ICU) after cardiac surgery.

METHODS

In this monocentric prospective observational study patients were postoperatively transferred to the ICU and both sensors were placed on the patients' foreheads. Core body temperature measured by intraoperatively placed PAC served as gold standard. Measurements were recorded at 5-minute intervals and up to 40 data sets per patient were recorded. Bland and Altman's method for repeated measurements was used to analyse agreement. Subgroup analyses for gender, body-mass-index, core temperature, airway status and different time intervals were performed. Lin's concordance correlation coefficient (LCCC) was calculated, as well as sensitivity and specificity for detecting hyperthermia (≥ 38 °C) and hypothermia (< 36 °C).

RESULTS

Over a period of six month, we collected 1600 sets of DS, ZHF, and PAC measurements, from a total of 40 patients. Bland-Altman analysis revealed a mean bias of -0.82 ± 1.27 °C (average ± 95% Limits-of-Agreement (LoA)) and - 0.54 ± 1.14 °C for DS and ZHF, respectively. The LCCC was 0.5 (DS) and 0.63 (ZHF). Mean bias was significantly higher in hyperthermic and hypothermic patients. Sensitivity and specificity were 0.12 / 0.99 (DS) and 0.35 / 1.0 (ZHF) for hyperthermia and 0.95 / 0.72 (DS) and 1.0 / 0.85 (ZHF) for hypothermia.

CONCLUSION

Core temperature was generally underestimated by the non-invasive approaches. In our study, ZHF outperformed DS. In terms of agreement, results for both sensors were outside the range that is considered clinically acceptable. Nevertheless, both sensors might be adequate to detect postoperative hypothermia reliably when more invasive methods are not available or appropriate.

TRIAL REGISTRATION

German Register of Clinical Trials (DRKS-ID: DRKS00027003), retrospectively registered 10/28/2021.

Troponin-T value as a prognostic marker in neonates diagnosed with neonatal encephalopathy and receiving hypothermia treatment

OBJECTIVE

The aim of this study was to investigate the effect of Troponin-T levels on the prognosis of neonatal encephalopathy (NE).

PATIENTS AND METHODS

The study included one hundred and eleven newborns diagnosed with NE and receiving hypothermia treatment. The cases were separated into 2 groups according to the SARNAT classification as Stage 2 or Stage 3. The groups were compared in respect of anthropometric characteristics, APGAR scores, and biochemical parameters. The cases were also separated into 3 groups according to the Troponin-T levels and were compared with respect to the clinical course.

RESULTS

The serum Troponin-T (p=0.012), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) (p<0.0001), and lactate levels (p=0.04) in the Sarnat Stage 3 group were statistically significantly higher than in the Sarnat stage 2 group. A significant positive correlation was determined between the Troponin-T level and the total duration of respiratory support (r=0.20, p=0.03). A significant positive correlation was determined between the ALT/AST ratio and the length of stay in hospital (r=0.29, p=0.001), duration of intubation (r=0.32, p=0.01), and total duration of respiratory support (r=0.36, p<0.001). A statistically significant difference was determined in mortality rates between the 3 subgroups of Troponin-T levels; Group 1: 2.8%, Group 2:5.4%, and Group 3: 15.8%. (p=0.04, χ²=4.74). A cut-off value of 164 ng/L for Troponin-T was determined to predict mortality with 77% sensitivity and 67% specificity (AUC=0.73, p=0.023). When the groups were compared according to Troponin-T level, a statistically significant difference was determined in respect of length of stay in hospital (p=0.03, χ²=6.95) and total duration of oxygen support (p=0.01, χ²=9.12).

CONCLUSIONS

The serum Troponin-T level can be evaluated as a prognostic marker in cases followed up with a diagnosis of NE and receiving hypothermia treatment. There is a need for further prospective studies with larger samples on this subject.

Cold Weather Injury in a Special Operations Aviation Crew Member: A Case Report

As arctic warfare becomes a center focus within Special Operations, cold weather injury looms as both a medical and operational threat. While cold weather injury can range from pernio to hemodynamically unstable systemic hypothermia, the more minor injuries are far more common. However, these present a challenge in austere medical care and can drastically impact mission capability. We present a case of a Special Operations crew chief with cold weather digital injury while at the Arctic Isolation Course in Alaska and his subsequent clinical course. Prevention remains the key for mitigating these injuries, while the decision to rewarm must be made with both medical and tactical factors in mind as refreezing incurs significant morbidity. Other components of prehospital treatment include active rewarming, ibuprofen, aloe vera, and pain control.

Agreement of infrared ear temperature with nasopharyngeal temperature and diagnostic performance on hypothermia in general anesthetized patients

BACKGROUND

Infrared ear thermometry is widely used in clinical practice due to its noninvasive, convenient, and quick sampling. However, its accuracy and feasibility in anesthetized patients have not yet been established.

METHODS

We conducted this cross-sectional study to evaluate the agreement between infrared ear temperature and nasopharyngeal temperature in general anesthetized patients and its performance in intraoperative hypothermia, defined as nasopharyngeal temperature <36°C. Adult female patients who underwent gynecological surgery under general anesthesia were enrolled in this study. Infrared ear temperature by Braun ThermoScan PRO 4000 (Braun GmbH, Kronberg, Germany) and nasopharyngeal temperature were measured simultaneously before, during, and after surgery. The agreement between the two temperatures was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. The diagnostic performance of the infrared ear thermometer for hypothermia was evaluated using receiver operating characteristic (ROC) curve analysis.

RESULTS

Fifty-six patients with 168 pairs of simultaneous infrared ear and nasopharyngeal temperatures were included in this analysis. The mean infrared ear temperature was consistently higher than the nasopharyngeal temperature throughout surgery, but the differences were small (0.22, 0.13, and 0.06°C before, during, and after surgery, respectively). The ICC between the two temperatures before, during, and after surgery was 0.70, 0.75, and 0.80, respectively, and 93.5% of the differences fell within the 95% limits of agreement of ±0.5°C. An infrared ear thermometer had high diagnostic accuracy for hypothermia, with an area under the ROC curve of 0.95 (95% confidence interval [CI], 0.92-0.98). The cutoff of infrared ear temperature for hypothermia was 36.2°C with a sensitivity of 0.89 (95% CI, 0.71-0.98) and a specificity of 0.87 (95% CI, 0.81-0.92).

CONCLUSION

The infrared ear temperature is in good agreement with the nasopharyngeal temperature in general anesthetized patients without hyperthermia and has high performance for detecting hypothermia. An infrared ear thermometer can be a diagnostic tool for intraoperative hypothermia.

Cold Weather Injuries: Initial Evaluation and Management

ABSTRACT

As more people take to extreme sporting activities and hobbies, the sports medicine physician should be proficient in early identification and initial sideline or field management of cold weather injuries. There is significant mortality and morbidity associated with these conditions. The most severe of these are hypothermia and frostbite, which have limited evidence for their field management. Nonfreezing cold injuries and chilblains are much rarer, although appropriate prevention and treatment strategies can be used to minimize harm to athletes. This article will provide the most updated recommendations for field or sideline evaluation and initial management of hypothermia, frostbite, nonfreezing cold injury, and chilblains.

[Antidepressant overdose resulting in coma and hypothermia]

BACKGROUND

Cognitive disorders lead to an increased risk of misuse of medication, resulting in possible auto-intoxication.

CASE DESCRIPTION

We describe the case of a 68-year-old patient, with hypothermia and a coma, with accidental tricyclic antidepressant (TCA) intoxication. What is remarkable about this case is that there were no cardiac or hemodynamic abnormalities, which is to be expected with both hypothermia and TCA-intoxication.

CONCLUSION

Intoxication should be considered in patients with hypothermia and a decreased level of consciousness, in addition to primarily neurological or metabolic causes. A good (hetero)anamnesis with attention to pre-existent cognitive functioning is important. Early screening for intoxication in patients with cognitive disorders with a coma and hypothermia is advisable, even in the absence of a typical toxidrome.

Validation of a Prediction Model for Intraoperative Hypothermia in Patients Receiving General Anesthesia

OBJECTIVES

There have been no fully validated tools for the rapid identification of surgical patients at risk of intraoperative hypothermia. The objective of this study was to validate the performance of a previously established prediction model in estimating the risk of intraoperative hypothermia in a prospective cohort.

METHODS

In this observational study, consecutive adults scheduled for elective surgery under general anesthesia were enrolled prospectively at a tertiary hospital between September 4, 2020, and December 28, 2020. An intraoperative hypothermia risk score was calculated by a mobile application of the prediction model. A wireless axillary thermometer was used to continuously measure perioperative core temperature as the reference standard. The discrimination and calibration of the model were assessed, using the area under the receiver operating characteristic curve (AUC), Hosmer-Lemeshow goodness-of-fit test, and Brier score.

RESULTS

Among 227 participants, 99 (43.6%) developed intraoperative hypothermia, and 10 (4.6%) received intraoperative active warming with forced-air warming. The model had an AUC of 0.700 (95% confidence interval [CI], 0.632-0.768) in the overall cohort with adequate calibration (Hosmer-Lemeshow χ ² = 13.8, P=0.087; Brier score = 0.33 [95% CI, 0.29-0.37]). We categorized the risk scores into low-risk, moderate-risk, and high-risk groups, in which the incidence of intraoperative hypothermia was 23.0% (95% CI, 12.4-33.5), 43.4% (95% CI, 33.7-53.2), and 62.7% (95% CI, 51.5-74.3), respectively (P for trend <0.001).

CONCLUSIONS

The intraoperative hypothermia prediction model demonstrated possibly helpful discrimination and adequate calibration in our prospective validation. These findings suggest that the risk screening model could facilitate future perioperative temperature management.

The Importance of BHB Testing on the Post-Mortem Diagnosis of Ketoacidosis

Although beta-hydroxybutyrate (BHB) analysis has proved its importance in forensic pathology, its effects on cause-of-death diagnostics are unaddressed. Therefore, this study aims at evaluating the effects of BHB analysis on the number of deaths by DKA (diabetes ketoacidosis), AKA (alcoholic ketoacidosis), HHS (hyperosmolar hyperglycaemic state), hypothermia, diabetes, alcoholism, and acidosis NOS (not otherwise specified). All 2900 deaths from 2013 through 2019 in which BHB was analysed at the National Board of Forensic Medicine, and 1069 DKA, AKA, HHS, hypothermia, diabetes, alcoholism, and acidosis cases without BHB analysis were included. The prevalence of BHB-positive cases for each cause of death, and trends and proportions of different BHB concentrations, were investigated. The number of BHB analyses/year increased from 13 to 1417. AKA increased from three to 66 and acidosis from one to 20. The deaths from alcoholism, DKA, and hypothermia remained stable. It is unclear why death from alcoholism remained stable while AKA increased. The increase in unspecific acidosis deaths raises the question why a more specific diagnosis had not been used. In conclusion, BHB analysis is instrumental in detecting AKA and acidosis. The scientific basis for the diagnosis of DKA and hypothermia improved, but the number of cases did not change.

Hypothermia in Young Infants: Frequency and Yield of Sepsis Workup

OBJECTIVES

Serious bacterial infections (SBIs) in young infants can present with fever or hypothermia. There are substantial data on fever as a presentation for SBI that help to inform the clinical approach. In contrast, data on hypothermia are lacking, thus leaving clinicians without guidance. We aimed to describe the workup and findings, specifically the occurrence, of SBIs in infants younger than 60 days of life with hypothermia.

METHODS

We reviewed the medical records of infants younger than 60 days of life with rectal temperature of less than 36.5°C upon arrival to a children's hospital emergency department between January 2013 and December 2014. Comparisons were made between those who were found to have an SBI and those without. Serious bacterial infection was defined as bacteremia, bacterial meningitis, pneumonia, or urinary tract infection (UTI).

RESULTS

From the 414 patients identified, 104 (25%) underwent a sepsis evaluation of blood, urine, and/or cerebrospinal fluid culture. Serious bacterial infections were identified in 9 patients: 4 with UTI, 1 with pneumonia, 2 with bacteremia, 1 with pneumonia and UTI, and 1 with meningitis and bacteremia. Compared with patients with negative cultures, patients with SBI were older and had elevated absolute band counts and elevated immature-to-total neutrophil ratio.

CONCLUSIONS

Approximately a quarter of infants younger than 60 days with hypothermia were evaluated for SBI. Serious bacterial infection was identified in 9% of evaluated infants (2% of all hypothermic infants). Hypothermia can be a presenting sign of SBI.

The accuracy of tactile assessment of canine nose temperature to identify rectal hyperthermia and hypothermia in dogs presenting on an emergency basis

The goals of this study were to evaluate whether touch can identify a warm nose as opposed to a cold nose, to examine the correlation between thermographically measured nose temperatures and rectal temperatures, and to calculate the accuracy of tactile assessment of nose temperature in detecting rectal hyperthermia and hypothermia in dogs. A total of 100 dogs presenting to an emergency room was prospectively enrolled. Tactile nose assessment was carried out on triage. Noses were subjectively categorized as warm, cold, or intermediate (neither warm nor cold). Thermographic nose temperatures were recorded using a thermal imaging camera. Tactile assessment categorized noses as warm, intermediate, or cold (P < 0.01). There was no correlation between thermographically measured nose temperature and rectal temperature (r = 0.02). Tactile assessment of noses as warm had a sensitivity of 29.4% and a specificity of 79.5% for detecting rectal hyperthermia; calculated test accuracy was 71%. Tactile assessment of noses as cold had a sensitivity of 54.5% and a specificity of 62.9%; calculated test accuracy was 62%. It was concluded that nose temperatures do not correlate with rectal temperatures. Tactile assessment of nose temperature is inaccurate for identifying rectal hyperthermia or hypothermia.

New-onset intra-operative hyperthermia in a large surgical patient population: A retrospective observational study

BACKGROUND

Intra-operative hypothermia has been extensively investigated. However, the incidence of intra-operative hyperthermia has not been investigated in detail.

OBJECTIVE

The main objective of this study was to assess the incidence and risk factors of new-onset intra-operative hyperthermia in a large surgical patient population.

DESIGN

Retrospective database review.

SETTING

Tertiary-care teaching hospital.

PATIENTS

Patients undergoing surgery with general anaesthesia between 1 January 2002 and 31 December 2017 were included.

MAIN OUTCOME MEASURES

The primary outcome measurement was new-onset intra-operative hyperthermia (>37.5 °C). A logistic regression model was fitted to identify risk factors for intra-operative hyperthermia.

RESULTS

A total of 103 648 patients were included in the final analyses. The incidence of new-onset hyperthermia in the overall patient cohort was 6.45%, reaching 20 to 30% after prolonged (>8 h) surgery, and was up to 26.5% in paediatric patients. The use of forced air active patient warming, larger amounts of fluid administration, longer surgery, younger age and smaller body size were all independently associated with intra-operative hyperthermia. The adoption of the Surgical Care Improvement Project (SCIP) temperature measures was associated with an increased incidence of intra-operative hyperthermia.

CONCLUSION

Mild intra-operative hyperthermia is not uncommon particularly in longer procedures and small children.

Death following extreme temperature exposure: Histological, biochemical and immunohistochemical markers

INTRODUCTION

Defining extreme temperatures as the cause of death remains challenging. It is mostly based on circumstantial, macroscopic and microscopic features.

METHODS

We retrospectively compared groups of cases of fatal hypothermia, fatal hyperthermia and non-extreme temperature-related deaths. We analysed specific histological findings, focusing on samples from the liver, pancreas and kidney.

RESULTS

Between 1 January 2013 and 31 December 2016, 15 autopsies were performed for deaths related to extreme temperatures. They included 11 cases of fatal hypothermia (group A), four cases of fatal hyperthermia (group B) and eight controls (group C). Perinuclear hepatocyte vacuolisation was observed in seven cases of hypothermia, one case of hyperthermia and four controls. Pancreatic cytoarchitecture was well preserved in two cases of hypothermia, one case of hyperthermia and two controls. No particular microscopic feature was found in pancreatic samples. Renal epithelial tubular cell vacuolisation was observed in seven cases of hypothermia and one case of hyperthermia, while it was absent in all controls. Chromogranin A (CgA) was markedly positive in the pancreatic tissue of five cases of fatal hypothermia and one control, and mildly positive in one case of fatal hyperthermia. No significant p-values were observed for any comparisons (p > 0.05), except when hypothermia cases group were compared to the control group for the Armanni-Ebstein phenomenon test (p = 0.0078).

CONCLUSIONS

Although our study did not find a specific microscopic marker, hepatocyte vacuolisation, the Armanni-Ebstein phenomenon and pancreatic CgA positivity, taken together, may be useful tools to confirm hypo- and hyperthermia-related deaths, in addition to circumstantial and macroscopic findings.

Prevalence of hypothermia on admission to recovery room remains high despite a large use of forced-air warming devices: Findings of a non-randomized observational multicenter and pragmatic study on perioperative hypothermia prevalence in France

BACKGROUND

Despite the availability of effective warming systems, the prevalence of hypothermia remains high in patients undergoing surgery. Occurrence of perioperative hypothermia may influence the rate of postoperative complications. Recommendations for the prevention of inadvertent perioperative hypothermia have been developed and are effective to reduce the frequency of perioperative hypothermia when professionals comply with. French Society of Anesthesiology (SFAR) decided to promote guidelines for the prevention of inadvertent hypothermia, and to conduct beforehand a pragmatic assessment of the prevalence of hypothermia in France. The hypothesis was that the rate of hypothermic patients (Tc<36°C) admitted to the RR remains high (around 50%), and that was the consequence of a warming device underutilization and/or was related to the type of health facilities.

METHODS

An observational, prospective and multi-centric study was conducted in France between October 2014 and May 2016 among patients over 45 years undergoing non-cardiac, non-outpatient surgery with anesthesia lasting >30 minutes in 52 centers. Patients undergoing pulmonary or proctologic surgery and those having non-invasive procedures performed under general anesthesia (for example, digestive endoscopy) were excluded from our study. Patients being operated under plexus anesthesia alone, surgeries involving hemorrhaging or infection, and patients presenting at least one organ failure were also excluded. The primary endpoint was the percentage of patients with a core temperature (Tc) <36°C on admission to the recovery room (RR).

RESULTS

Among 893 subjects (median age 66.9 years), prevalence of hypothermia on admission to the RR was 53.5%. At least one warming system was used for 90.4% of the patients. Identified risk factors for Tc<36°C included age≥70 years (OR = 1.41 [CI95%: 1.02-1.94]), duration of anesthesia from 1 to 2 hours (OR = 1.94 [CI95%: 1.04-3.64]) and a decrease in Tc of >0.5°C between anesthesia induction and surgical incision (OR = 1.82 [CI95%: 1.15-2.89]). Only a combination of pre-warming and intraoperative warming prevented a Tc<36°C (OR = 0.48 [CI95%: 0.24-0.96]).

CONCLUSIONS

The prevalence of hypothermia among patients admitted to the RR remains high. Our results suggest that only the combination of pre-warming and intraoperative warming significantly decreases it.

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.

Hypothermia detection in low birth weight neonates using a novel bracelet device

OBJECTIVE

The objective of this study is to assess the diagnostic accuracy of a novel hypothermia monitoring and alert bracelet device (BEMPU Bracelet) in low birth weight (LBW) neonates weighing less than 2000 g.

DESIGN

This was a controlled prospective study.

SETTING

This study was done in the step-down nursery of a tertiary level newborn unit of a major teaching hospital in India.

METHODS

Eligible cases fulfilling inclusion criteria were given BEMPU Bracelets for a period of 24 h. A comparison was made between skin temperatures taken at the axilla by a mercury thermometer and skin temperatures taken at the wrist by the BEMPU Bracelet. Temperatures were taken every 6 h and every time the BEMPU Bracelet alarmed. Trained nurses obtained temperature measurements on newborns during their 24-h stay in the hospital step-down nursery.

RESULTS

A total of 461 neonates were screened for hypothermia, giving 2428 temperature readings. Three hundred and eleven of 461 babies experienced hypothermia at some point. The 461 babies studied experienced 495 episodes of hypothermia in total. The sensitivity and the specificity of the bracelet in diagnosing hypothermia were 98.6% and 95% respectively. The positive and negative predictive values of the bracelet were 83.6% and 99.6%, respectively. The accuracy of the bracelet in diagnosing hypothermia was 95.8%.

CONCLUSION

The BEMPU Bracelet is an accurate screening tool to detect and alert for neonatal hypothermia, thereby facilitating prompt management, which could prevent complications.

Updated review of postmortem biochemical exploration of hypothermia with a presentation of standard strategy of sampling and analyses

Hypothermia is defined as a core body temperature below 35°C and can be caused by environmental exposure, drug intoxication, metabolic or nervous system dysfunction. This lethal pathology with medico-legal implications is complex to diagnose because macroscopic and microscopic lesions observed at the autopsy and the histological analysis are suggestive but not pathognomonic. Postmortem biochemical explorations have been progressively developed through the study of several biomarkers to improve the diagnosis decision cluster. Here, we present an updated review with novel biomarkers (such as catecholamines O-methylated metabolites, thrombomodulin and the cardiac oxyhemoglobin ratio) as well as some propositional interpretative postmortem thresholds and, to the best of our knowledge, for the first time, we present the most adapted strategy of sampling and analyses to identify biomarkers of hypothermia. For our consideration, the most relevant identified biomarkers are urinary catecholamines and their O-methylated metabolites, urinary free cortisol, blood cortisol, as well as blood, vitreous humor and pericardial fluid for ketone bodies and blood free fatty acids. These biomarkers are increased in response either to cold-mediated stress or to bioenergetics ketogenesis crisis and significantly contribute to the diagnosis by exclusion of death by hypothermia.

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.

Management of pediatric hypothermia and peripheral cold injuries in the emergency department

Hypothermia occurs when the core body temperature falls below 35ºC (95ºF) due to primary exposure (eg, environmental exposure) or secondary to other pathologies. Infants, children, and adolescents are at higher risk for primary cold injuries due to a combination of physiologic and cognitive factors, but quick rewarming and appropriate disposition can result in survival and improved neurological outcomes. Treatment for cold injuries is guided by severity and can include passive or active measures. This issue reviews the stages of hypothermia and offers recommendations for emergent management of pediatric patients with hypothermia; guidance is also provided for the identification and management of frostnip and frostbite.

Back to Basics: Unplanned Patient Hypothermia: 1.3 www.aornjournal.org/content/cme

Unplanned perioperative hypothermia is a common occurrence and can negatively affect a patient's postoperative course. Perioperative nurses are responsible for identifying patients at risk for hypothermia and working with the entire surgical team to prevent this complication from occurring. Multiple interventions can be implemented to address hypothermia, including active or passive warming and warm IV and irrigation fluids. This Back to Basics article addresses patient assessment concerns, identifies a variety of evidence-based interventions that can prevent or mitigate perioperative patient temperature changes, and provides basic steps for perioperative RNs to follow to help prevent perioperative hypothermia in their patients.

Continuous Temperature Monitoring Using Bluetooth- enabled Thermometer in Neonates

We aimed to compare continuous temperature-monitoring using Bluetooth-enabled thermometer (BET) and intermittent monitoring by digital thermometer (DT) in neonates. Continuous monitoring using BET identified 377 episodes of hypo/hyperthermias in 90 baby-days; 316 (83.8%) episodes were confirmed by DT and 61 (16.2%) were false alarms. Five episodes were missed by BET. The agreement between digital thermometer and BET was good. Continuous temperature monitoring helps in early identification of hypo/hyperthermia in neonates.

GUIDELINES FOR MANAGEMENT OF ACCIDENTAL HYPOTHERMIA IN A UNIVERSITY HOSPITAL IN NORTHERN NORWAY

Accidental hypothermia is defined as a trauma. Collaboration on the treatment of victims of accidental hypothermia shouldfollow a communication protocol for the seriously injured. Aim is to establish earliest possible contact with the doctor on duty at the regional University hospital to enable participation in the further communication and decision making process with relevance to technical and logistical issues. Victims of accidental hypothermia with adequate circulation and core temperature < 35⁰C can be treated with active remote heating (hot air blanket) at all hospitals providing emergency surgical care; active external warming should be started during transport to the nearest hospital. Hypothermic patients showing no signs of life, patients with inadequate circulation or hypothermia-induced circulatory arrest with core temperature < 32⁰C and serum K⁺ < 12 mmol-l⁻' should be transported directly to University hospital. Advanced life support in all these cases should be started immediately and continued without interruption during transportation until the patient is connected to a heart-lung machine for rewarming. If core temperature is < 28⁰C and/or the patient has inadequate circulation contact should be taken with the regional University hospital to discuss extracorporeal rewarming.

Hypothermia in adults: A strategy for detection and Tx

Whether hypothermia is a result of environmental exposure or illness, it's important to identify predictable patterns of physiologic response and focus on proper Tx.

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Zusammenfassung. Ein 70-jähriger Patient wurde nach einem Bootsunfall mit verminderter Körpertemperatur (Hypothermie Stadium II) in die Notaufnahme eingeliefert. Aufgrund des vorliegenden Verwirrtheitszustandes war keine klare Anamnese zu erheben, weswegen eine sekundäre Hypothermie zu Beginn nicht ausgeschlossen werden konnte. Die arterielle BGA wies eine schwere metabolische Laktatazidose auf. Ausserdem zeigte das EKG J-Wellen, positive Ausschläge am Ende des QRS-Komplexes, welche typisch für eine Hypothermie sind. Nach Erwärmung mittels warmer Infusionslösungen und konvektiver Wärmeleitsysteme normalisierten sich sowohl der EKG-Befund als auch der Säure-Basen-Haushalt.

Measuring core temperature using the proprietary application and thermo-smartphone adapter

Fast and accurate measurement of core body temperature is crucial for accidental hypothermia treatment. We have developed a novel light and small adapter to the headset jack of a mobile phone based on Android. It has been applied to measure temperature and set up automatic notifications (e.g. Global Positioning System coordinates to emergency services dispatcher, ECMO coordinator). Its validity was confirmed in comparison with Vital Signs Monitor Spacelabs Healthcare Elance 93300 as a reference method, in a series of 260 measurements in the temperature range of 10-42 °C. Measurement repeatability was verified in a battery of 600 measurements (i.e. 100 readings at three points of 10, 25, 42 °C for both esophageal and tympanic catheters). Inter-method difference of ≤0.5 °C was found for 98.5% for esophageal catheter and 100% for tympanic catheter measurements, with concordance correlation coefficient of 0.99 for both. The readings were almost completely repeatable with water bath measurements (difference of ≤0.5 °C in 10 °C: 100% for both catheters; in 25 °C: 99% for esophageal catheter and 100% tympanic catheter; in 42 °C: 100% for both catheters). This lightweight adapter attached to smartphone and standard disposable probes is a promising tool to be applied on-site for temperature measurement in patients at risk of hypothermia.

[Nontraumatic medical emergencies in mountain rescues]

OBJECTIVES

To describe the clinical and epidemiologic characteristics of patients with nontraumatic medical problems rescued by a Spanish mountain emergency response service (061 Aragon).

MATERIAL AND METHODS

Retrospective observational analysis of records of mountain rescues completed between July 2010 and December 2016.

RESULTS

A total of 164 patients with nontraumatic medical emergencies were rescued; 82.3% were males. Most patients were between the ages of 50 and 59 years. Environmentally related problems, most often hypothermia, accounted for 36.6% of the emergencies. Cardiac problems led to 20.7% and digestive problems to 12.8%. Eighty-two percent of the patients were hiking or engaged in general mountain activities (other than rock climbing, canyoning, hunting, or skiing).

CONCLUSION

Recent years have seen a rise in the number of patients requiring rescue from mountains for nontraumatic medical emergencies, particularly heart problems. The typical patient to expect would be a man between the ages of 50 and 59 years who is hiking in the summer.

Altered Level Of Consciousness: Evidence-Based Management In The Emergency Department

A child who presents to the emergency department with an altered level of consciousness can be clinically unstable and can pose a great diagnostic challenge. The emergency clinician must quickly develop a wide differential of possible etiologies in order to administer potentially life-saving medications or interventions. The history, physical examination, and appropriate diagnostic tests can aid greatly in rapidly narrowing the differential diagnosis. Once initial stabilization, workup, and first-line interventions are completed, most patients who present with unresolved or unidentified altered level of consciousness should be admitted for further evaluation and close monitoring. This issue provides a review of the etiologies of altered level of consciousness as well as guidance for the management and disposition of patients with this condition.

Research: Testing of a Novel Portable Body Temperature Conditioner Using a Thermal Manikin

A battery-operated active cooling/heating device was developed to maintain thermoregulation of trauma victims in austere environments while awaiting evacuation to a hospital for further treatment. The use of a thermal manikin was adopted for this study in order to simulate load testing and evaluate the performance of this novel portable active cooling/heating device for both continuous (external power source) and battery power. The performance of the portable body temperature conditioner (PBTC) was evaluated through cooling/heating fraction tests to analyze the heat transfer between a thermal manikin and circulating water blanket to show consistent performance while operating under battery power. For the cooling/heating fraction tests, the ambient temperature was set to 15°C ± 1°C (heating) and 30°C ± 1°C (cooling). The PBTC water temperature was set to 37°C for the heating mode tests and 15°C for the cooling mode tests. The results showed consistent performance of the PBTC in terms of cooling/heating capacity while operating under both continuous and battery power. The PBTC functioned as intended and shows promise as a portable warming/cooling device for operation in the field.

The Significance of Hypothermia in Abdominal Aortic Aneurysm Repair

BACKGROUND

The aim of this study was to review the literature on the association between hypothermia and outcomes in open and endovascular abdominal aortic aneurysm (AAA) repair. The secondary aim was to determine whether there is a difference in body temperature in patients undergoing either transperitoneal (TP), retroperitoneal (RP), or endovascular surgical repair of the abdominal aorta (EVAR).

METHODS

MEDLINE, Web of Science, and Trip searched for all studies on temperature in the context of aortic surgery or endovascular aortic interventions. To be included in the review, the papers had to be related to intraoperative or postoperative hypothermia and/or normothermia, with regards to either open or endovascular repair of the abdominal aorta. Thoracic or thoracoabdominal aortic repairs were not included for review.

RESULTS

Eight studies involving 765 patients were eligible. Of these, 6 studies looked at open elective AAA repair involving 605 patients. Only 2 studies investigated emergency AAA repair and consisted of 160 patients where only 35 of those patients underwent emergency EVAR. Normothermic patients had a shorter length of stay in the intensive care unit (P = 0.0008), while hypothermia was independently associated with higher rates of organ dysfunction, in-hospital mortality, and prolonged hospital length of stay. In ruptured AAAs, the lowest average intraoperative temperature was recorded in open repair compared with EVAR (P = 0.02). There was no statistically significant difference in postoperative temperature between patients undergoing elective RP repair and those having TP surgery.

CONCLUSIONS

The studies identified in this review have shown that hypothermia has numerous deleterious effects on outcomes in AAA repair - whether or not these adverse outcomes are those such as higher rates of organ dysfunction, mortality or prolonged hospital length of stay, can only be done at the single paper level and not at a literature review level, due to multiple confounding variables. Despite these limitations, the benefits of this review are numerous. This article highlights the importance of core body temperature and outcomes of AAA repair. Furthermore, it brings forth the need to standardize the method of core body temperature measurement and method of rewarming. Given the body of evidence so far, these standardized data collection points will be important for national vascular quality improvement initiatives. Only through rigorous analysis of standardized dataset can firm recommendation regarding peri- and postoperative temperature management be made.