Severe accidental hypothermia treated in an ICU: prognosis and outcome

Accidental hypothermia in Poland – estimation of prevalence, diagnostic methods and treatment

BACKGROUND

The incidence of hypothermia is difficult to evaluate, and the data concerning the morbidity and mortality rates do not seem to fully represent the problem. The aim of the study was to estimate the actual prevalence of accidental hypothermia in Poland, as well as the methods of diagnosis and management procedures used in emergency rooms (ERs).

METHODS

A specially designed questionnaire, consisting of 14 questions, was mailed to all the 223 emergency rooms (ER) in Poland. The questions concerned the incidence, methods of diagnosis and risk factors, as well as the rewarming methods used and available measurement instruments.

RESULTS

The analysis involved data from 42 ERs providing emergency healthcare for the population of 5,305,000. The prevalence of accidental hypothermia may have been 5.05 cases per 100.000 residents per year. Among the 268 cases listed 25% were diagnosed with codes T68, T69 or X31, and in 75% hypothermia was neither included nor assigned a code in the final diagnosis. The most frequent cause of hypothermia was exposure to cold air alongside ethanol abuse (68%). Peripheral temperature was measured in 57%, core temperature measurement was taken in 29% of the patients. Peripheral temperature was measured most often at the axilla, while core temperature measurement was predominantly taken rectally. Mild hypothermia was diagnosed in 75.5% of the patients, moderate (32-28°C) in 16.5%, while severe hypothermia (less than 28°C) in 8% of the cases. Cardiopulmonary resuscitation was carried out in 7.5% of the patients. The treatment involved mainly warmed intravenous fluids (83.5%) and active external rewarming measures (70%). In no case was extracorporeal rewarming put to use.

CONCLUSIONS

The actual incidence of accidental hypothermia in Polish emergency departments may exceed up to four times the official data. Core temperature is taken only in one third of the patients, the treatment of hypothermic patients is rarely conducted in intensive care wards and extracorporeal rewarming techniques are not used. It may be expected that personnel education and the development of management procedures will brighten the prognosis and increase the survival rate in accidental hypothermia.

Milrinone ameliorates cardiac mechanical dysfunction after hypothermia in an intact rat model

BACKGROUND

Rewarming from hypothermia is often complicated by cardiac dysfunction, characterized by substantial reduction in stroke volume. Previously we have reported that inotropic agents, working via cardiac β-receptor agonism may exert serious side effects when applied to treat cardiac contractile dysfunction during rewarming. In this study we tested whether Milrinone, a phosphodiesterase III inhibitor, is able to ameliorate such dysfunction when given during rewarming.

METHODS

A rat model designed for circulatory studies during experimental hypothermia with cooling to a core temperature of 15°C, stable hypothermia at this temperature for 3h and subsequent rewarming was used, with a total of 3 groups: (1) a normothermic group receiving Milrinone, (2) a hypothermic group receiving Milrinone the last hour of hypothermia and during rewarming, and (3) a hypothermic saline control group. Hemodynamic function was monitored using a conductance catheter introduced to the left ventricle.

RESULTS

After rewarming from 15°C, stroke volume and cardiac output returned to within baseline values in Milrinone treated animals, while these variables were significantly reduced in saline controls.

CONCLUSIONS

Milrinone ameliorated cardiac dysfunction during rewarming from 15°C. The present results suggest that at low core temperatures and during rewarming from such temperatures, pharmacologic efforts to support cardiovascular function is better achieved by substances preventing cyclic AMP breakdown rather than increasing its formation via β-receptor stimulation.

Hypothermia in victims of the great East Japan earthquake: a survey in Miyagi prefecture

OBJECTIVE

A survey was conducted to describe the characteristics of patients treated for hypothermia after the Great East Japan Earthquake.

METHODS

Written questionnaires were distributed to 72 emergency medical hospitals in Miyagi Prefecture. Data were requested regarding inpatients with a temperature less than 36ºC admitted within 72 hours after the earthquake. The availability of functional heating systems and the time required to restore heating after the earthquake were also documented.

RESULTS

A total of 91 inpatients from 13 hospitals were identified. Tsunami victims comprised 73% of the patients with hypothermia. Within 24 hours of the earthquake, 66 patients were admitted. Most patients with a temperature of 32ºC or higher were treated with passive external rewarming with blankets. Discharge without sequelae was reported for 83.3% of patients admitted within 24 hours of the earthquake and 44.0% of those admitted from 24 to 72 hours after the earthquake. Heating systems were restored within 3 days of the earthquake at 43% of the hospitals.

CONCLUSIONS

Hypothermia in patients hospitalized within 72 hours of the earthquake was primarily due to cold-water exposure during the tsunami. Many patients were successfully treated in spite of the post-earthquake disruption of regional social infrastructure.

Vital signs, QT prolongation, and newly diagnosed cardiovascular disease during severe hypoglycemia in type 1 and type 2 diabetic patients

OBJECTIVE To assess vital signs, QT intervals, and newly diagnosed cardiovascular disease during severe hypoglycemia in diabetic patients. RESEARCH DESIGN AND METHODS From January 2006 to March 2012, we conducted a retrospective cohort study to assess type 1 and type 2 diabetic patients with severe hypoglycemia at a national center in Japan. Severe hypoglycemia was defined as the presence of any hypoglycemic symptoms that could not be resolved by the patients themselves in prehospital settings. RESULTS A total of 59,602 cases that visited the emergency room by ambulance were screened, and 414 cases of severe hypoglycemia were analyzed. The median (interquartile range) blood glucose levels were not significantly different between the type 1 diabetes mellitus (T1DM) (n = 88) and type 2 diabetes mellitus (T2DM) (n = 326) groups (32 [24-42] vs. 31 [24-39] mg/dL, P = 0.59). During severe hypoglycemia, the incidences of severe hypertension (≥180/120 mmHg), hypokalemia (<3.5 mEq/L), and QT prolongation were 19.8 and 38.8% (P = 0.001), 42.4 and 36.3% (P = 0.30), and 50.0 and 59.9% (P = 0.29) in the T1DM and T2DM groups, respectively. Newly diagnosed cardiovascular disease during severe hypoglycemia and death were only observed in the T2DM group (1.5 and 1.8%, respectively). Blood glucose levels between the deceased and surviving patients in the T2DM group were significantly different (18 [14-33] vs. 31 [24-39] mg/dL, P = 0.02). CONCLUSIONS T1DM and T2DM patients with severe hypoglycemia experienced many critical problems that could lead to cardiovascular disease, fatal arrhythmia, and death.

Role of calcium desensitization in the treatment of myocardial dysfunction after deep hypothermic circulatory arrest

Introduction

Rewarming from deep hypothermic circulatory arrest (DHCA) produces calcium desensitization by troponin I (cTnI) phosphorylation which results in myocardial dysfunction. This study investigated the acute overall hemodynamic and metabolic effects of epinephrine and levosimendan, a calcium sensitizer, on myocardial function after rewarming from DHCA.

Methods

Forty male Wistar rats (400 to 500 g) underwent cardiopulmonary bypass (CPB) through central cannulation and were cooled to a core temperature of 13°C to 15°C within 30 minutes. After DHCA (20 minutes) and CPB-assisted rewarming (60 minutes) rats were randomly assigned to 60 minute intravenous infusion with levosimendan (0.2 μg/kg/min; n = 15), epinephrine (0.1 μg/kg/min; n = 15) or saline (control; n = 10). Systolic and diastolic functions were evaluated at different preloads with a conductance catheter.

Results

The slope of left ventricular end-systolic pressure volume relationship (Ees) and preload recruitable stroke work (PRSW) recovered significantly better with levosimendan compared to epinephrine (Ees: 85 ± 9% vs 51 ± 11%, P<0.003 and PRSW: 78 ± 5% vs 48 ± 8%, P<0.005; baseline: 100%). Levosimendan but not epinephrine reduced left ventricular stiffness shown by the end-diastolic pressure-volume relationship and improved ventricular relaxation (Tau). Levosimendan preserved ATP myocardial content as well as energy charge and reduced plasma lactate concentrations. In normothermia experiments epinephrine in contrast to Levosimendan increased cTnI phosphorylation 3.5-fold. After rewarming from DHCA, cTnI phosphorylation increased 4.5-fold in the saline and epinephrine group compared to normothermia but remained unchanged with levosimendan.

Conclusions

Levosimendan due to prevention of calcium desensitization by cTnI phosphorylation is more effective than epinephrine for treatment of myocardial dysfunction after rewarming from DHCA.

Mild hypothermia decreases arrhythmia susceptibility in a canine model of global myocardial ischemia*

OBJECTIVES

Although the majority of sudden cardiac arrests occur in patients with ischemic heart disease, the effect of therapeutic hypothermia on arrhythmia susceptibility during acute global ischemia is not well understood. While both ischemia and severe hypothermia are arrhythmogenic, patients undergoing therapeutic hypothermia do not have an increase in arrhythmias, despite the fact that most sudden cardiac arrest occur in the setting of ischemia. We hypothesized that mild hypothermia induced prior to myocardial ischemia and reperfusion will have a beneficial effect on ischemia-related arrhythmia substrates.

DESIGN

We developed a model of global ischemia and reperfusion in the canine wedge preparation to study the transmural electrophysiologic effects of ischemia at different temperatures.

SETTING

Animal study.

SUBJECTS

Male mongrel dogs.

INTERVENTIONS

Canine left ventricle wedge preparations at 1) control (36°C) or 2) mild hypothermia, to simulate temperatures used in therapeutic hypothermia (32°C), were subjected to 15 mins of no-flow ischemia and subsequently reperfused.

MEASUREMENTS AND MAIN RESULTS

Optical action potentials were recorded spanning the transmural wall of left ventricle. Action potential duration for epicardial, mid-myocardial, and epicardial cells was measured. Transmural dispersion of repolarization and conduction velocity were measured at baseline, during ischemia, and during reperfusion. No difference was seen at baseline for conduction velocity or dispersion of repolarization between groups. Conduction velocity decreased from 0.46 ± 0.02 m/sec to 0.23 ± 0.07 m/sec, and dispersion of repolarization increased from 30 ± 5 msecs to 57 ± 4 msecs in the control group at 15 mins of ischemia. Mild hypothermia attenuated both the ischemia-induced conduction velocity slowing (decreasing from 0.44 ± 0.02 m/sec to 0.35 ± 0.03 m/sec; p = .019) and the ischemia-induced increase in dispersion of repolarization (25 ± 3 msecs to 37 ± 7 msecs; p = .037). Epicardial conduction block was observed in six of seven preparations of the control group, but no preparations in the mild hypothermia group developed conduction block (0/6).

CONCLUSIONS

Mild hypothermia attenuated ischemia-induced increase in dispersion of repolarization, conduction slowing, and block, which are known mechanisms of arrhythmogenesis in ischemia. These data suggest that therapeutic hypothermia may decrease arrhythmogenesis during myocardial ischemia.

Peripheral neuropathy caused by severe hypothermia

OBJECTIVE

To report follow-up data in the evaluation of peripheral neuropathy in a 29-year old female after accidental deep hypothermia (13.7°C) in 1999.

METHODS

Nerve conduction studies (NCS) and electromyography (EMG) were performed 20 days after the accident and again after 5 months and 1, 3, 5 and 11 years. Macro EMG was performed after 3, 5 and 11 years. To evaluate small fiber function, RR-interval, sympathetic skin response, quantitative sensory testing and skin biopsy for quantification of intra-epidermal nerve fiber density were performed in 2009.

RESULTS

In the intensive care unit sensory and motor responses were absent except for the tibial nerves, and EMG showed profuse denervation. Improvement of amplitudes and conduction velocities was seen during the first 5 years. Muscular atrophy of hand muscles persisted. Large fibers were involved more extensively than small fibers.

CONCLUSIONS

A severe axonal sensorimotor polyneuropathy developed in the intensive care unit following severe hypothermia. The mechanism was most likely cold injury to peripheral nerves.

SIGNIFICANCE

The clinical picture and the laboratory findings indicate that even multi-organ dysfunction and, of specific interest in this study, a severe axonal degeneration may come to a good restitution after long time.

Early use of hemodialysis for active rewarming in severe hypothermia: a case report and review of literature

Deep accidental hypothermia (body temperature below 28°C) is rare. Even with modern supportive care of active external and internal rewarming techniques it is associated with a high mortality rate. We report the early and successful use of hemodialysis (HD) for active rewarming of a middle-aged alcoholic man with severe deep accidental hypothermia after failure of initial efforts of rewarming using conventional strategies. This case report and review of the literature highlights the advantages and the challenges of using HD in this setting and suggests a potential role for HD in the routine management of severe hypothermia in the absence of circulatory arrest.

Efficacy of portable and percutaneous cardiopulmonary bypass rewarming versus that of conventional internal rewarming for patients with accidental deep hypothermia

OBJECTIVE

Since 2001, at our institution, a portable and percutaneous cardiopulmonary bypass system has been used for rewarming of patients with accidental deep hypothermia. Before 2001, a conventional internal rewarming technique was used. The aim of this research is to examine the efficacy of portable and percutaneous cardiopulmonary bypass for rewarming of patients with accidental severe hypothermia and compare it with that of conventional rewarming methods.

DESIGN

Historical study.

SETTING

The exclusive emergency medical center and trauma center level 1 in Western Kanagawa, Japan.

PATIENTS

From April 1992 to March 2009, 70 patients with accidental deep hypothermia (core temperature <28°C) were transferred to our hospital. Two patients presented with intracranial hemorrhage on initial head computed tomography scans. These two patients were excluded because each required an emergency operation. Therefore, 68 patients were included in this study. We compared patients' clinical characteristics and outcomes. The parameters included the following: sex, age, vital signs on arrival to our hospital (Glasgow coma Scale scores, systolic blood pressure, heart rate, respiratory rate, core temperature), electrocardiogram on arrival to our hospital, rewarming speed, time of rewarming until 34°C was reached, ventricular fibrillation occurrence rate during rewarming, cause of cold environmental exposure, Glasgow Outcome Scale scores, and mortality. In addition, we divided the conventional and portable and percutaneous cardiopulmonary bypass rewarming groups into two categories depending on whether cardiopulmonary arrest occurred on arrival to our hospital. We also compared the survival rate and average Glasgow Outcome Scale scores for each group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients' clinical backgrounds did not differ significantly between the conventional and portable and percutaneous cardiopulmonary bypass rewarming groups. Glasgow Outcome Scale scores and survival rates of the portable and percutaneous cardiopulmonary bypass rewarming group patients, irrespective of whether cardiopulmonary arrest was experienced on arrival to our hospital, were significantly higher than those of the conventional rewarming group.

CONCLUSIONS

Portable and percutaneous cardiopulmonary bypass rewarming can improve the mortality rates and Glasgow Outcome Scale scores of accidental deep hypothermia patients.

Active intravascular rewarming for hypothermia associated with traumatic injury: early experience with a new technique

Hypothermia is a significant contributor to mortality in severely injured patients. Rewarming is an enormous challenge, especially in those who require operative or angiographic intervention. In this patient population, external warming methods are only capable of reducing further heat loss, whereas active rewarming adds heat to the body's core but is invasive. This article analyzes our initial experience with a minimally invasive, continuous, automated, and easily portable intravascular rewarming technique using the Alsius Corporation's CoolGard system. The records of 11 hypothermic critically injured patients presenting to our level 1 trauma center over a 6-month period were reviewed. The patients' mean age was 39 +/- 22 years, 7 (64%) were male, and 7 (64%) had blunt mechanisms of injury. The mean injury severity score was 40 +/- 16, and the mean initial systolic blood pressure was 91 +/- 60 mm Hg. The mean core temperature at the initiation of rewarming was 33.6 +/- 1.0 degrees C, and the mean rewarming rate was 1.5 +/- 1.0 degrees C/h. Six patients died (55%), two of acute exsanguination and four of unsurvivable traumatic brain injuries. One patient developed a deep vein thrombosis at the femoral catheter site and experienced a nonfatal pulmonary embolus. Our experience demonstrates that active intravascular balloon-catheter rewarming represents a practical, automated technique for the immediate and continuous treatment of hypothermia in all phases of the acute care of trauma patients.

Hypothermia with pneumonia: a rare presentation of brucellosis

OBJECTIVE

To report a very rare form of brucellosis presenting with hypothermia and pneumonia.

CLINICAL PRESENTATION AND INTERVENTION

A 41-year-old male shepherd presented with a depressed level of consciousness. Clinically, his rectal temperature was 29.5°C, and he was cold, apathetic, hyporeflexic, and hypotensive, with atrial fibrillation. He had clinical and radiological evidence of bilateral bronchopneumonia. Blood culture and serologic testing were positive for Brucella melitensis. The patient recovered completely after proper management of the hypothermia and treatment of the brucellosis with antibiotics (doxycycline 100 mg orally twice daily for 6 weeks and streptomycin 1 g i.m. daily for 21 days).

CONCLUSION

This case shows that brucellosis should be considered in the differential diagnosis of septicemic patients presenting with hypothermia.

Enhanced dispersion of repolarization explains increased arrhythmogenesis in severe versus therapeutic hypothermia

BACKGROUND

Hypothermia is proarrhythmic, and, as the use of therapeutic hypothermia (TH) increases, it is critically important to understand the electrophysiological effects of hypothermia on cardiac myocytes and arrhythmia substrates. We tested the hypothesis that hypothermia-enhanced transmural dispersion of repolarization (DOR) is a mechanism of arrhythmogenesis in hypothermia. In addition, we investigated whether the degree of hypothermia, the rate of temperature change, and cooling versus rewarming would alter hypothermia-induced arrhythmia substrates.

METHODS AND RESULTS

Optical action potentials were recorded from cells spanning the transmural wall of canine left ventricular wedge preparations at baseline (36°C), during cooling and during rewarming. Electrophysiological parameters were examined while varying the depth of hypothermia. On cooling to 26°C, DOR increased from 26±4 ms to 93±18 ms (P=0.021); conduction velocity decreased from 35±5 cm/s to 22±5 cm/s (P=0.010). On rewarming to 36°C, DOR remained prolonged, whereas conduction velocity returned to baseline. Conduction block and reentry was observed in all severe hypothermia preparations. Ventricular fibrillation/ventricular tachycardia was seen more during rewarming (4/5) versus cooling (2/6). In TH (n=7), cooling to 32°C mildly increased DOR (31±6 to 50±9, P=0.012), with return to baseline on rewarming and was associated with decreased arrhythmia susceptibility. Increased rate of cooling did not further enhance DOR or arrhythmogenesis.

CONCLUSIONS

Hypothermia amplifies DOR and is a mechanism for arrhythmogenesis. DOR is directly dependent on the depth of cooling and rewarming. This provides insight into the clinical observation of a low incidence of arrhythmias in TH and has implications for protocols for the clinical application of TH.

Post-hypothermic cardiac left ventricular systolic dysfunction after rewarming in an intact pig model

INTRODUCTION

We developed a minimally invasive, closed chest pig model with the main aim to describe hemodynamic function during surface cooling, steady state severe hypothermia (one hour at 25°C) and surface rewarming.

METHODS

Twelve anesthetized juvenile pigs were acutely catheterized for measurement of left ventricular (LV) pressure-volume loops (conductance catheter), cardiac output (Swan-Ganz), and for vena cava inferior occlusion. Eight animals were surface cooled to 25°C, while four animals were kept as normothermic time-matched controls.

RESULTS

During progressive cooling and steady state severe hypothermia (25°C) cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), maximal deceleration of pressure in the cardiac cycle (dP/dt(min)), indexes of LV contractility (preload recruitable stroke work, PRSW, and maximal acceleration of pressure in the cardiac cycle, dP/dt(max)) and LV end diastolic and systolic volumes (EDV and ESV) were significantly reduced. Systemic vascular resistance (SVR), isovolumetric relaxation time (Tau), and oxygen content in arterial and mixed venous blood increased significantly. LV end diastolic pressure (EDP) remained constant. After rewarming all the above mentioned hemodynamic variables that were depressed during 25°C remained reduced, except for CO that returned to pre-hypothermic values due to an increase in heart rate. Likewise, SVR and EDP were significantly reduced after rewarming, while Tau, EDV, ESV and blood oxygen content normalized. Serum levels of cardiac troponin T (TnT) and tumor necrosis factor-alpha (TNF-α) were significantly increased.

CONCLUSIONS

Progressive cooling to 25°C followed by rewarming resulted in a reduced systolic, but not diastolic left ventricular function. The post-hypothermic increase in heart rate and the reduced systemic vascular resistance are interpreted as adaptive measures by the organism to compensate for a hypothermia-induced mild left ventricular cardiac failure. A post-hypothermic increase in TnT indicates that hypothermia/rewarming may cause degradation of cardiac tissue. There were no signs of inadequate global oxygenation throughout the experiments.

Hemodialysis as a treatment of severe accidental hypothermia

We describe a case of severe accidental hypothermia (core body temperature 23.2 degrees C) successfully treated with hemodialysis in a diabetic patient with preexisting renal insufficiency. Consensus exists about cardiopulmonary bypass as the treatment of choice in cases of severe accidental hypothermia with cardiac arrest. Prospective randomized controlled trials comparing the different rewarming modalities for hemodynamically stable patients with hypothermia, however, are lacking. In our opinion, the choice of a rewarming technique should be patient tailored, knowing that hemodialysis is an efficient, minimally invasive, and readily available technique with the advantage of providing electrolyte support.

[Effects of induced hypothermia in critically ill children]

OBJECTIVE

To study the efficacy of induced hypothermia (IH) in children, its effect on hemodynamic, hematological, and biochemical parameters and its side effects.

DESIGN

Retrospective, observational study.

SETTING

Pediatric intensive care unit.

PATIENTS

Pediatric patients requiring induced hypothermia.

INTERVENTIONS

None.

DATA COLLECTED

The following variables were recorded prior to the initiation of IH and after 4, 24, 48, 72, and 120 hours: heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), diuresis, dose of inotropic, sedative, and muscle relaxant drugs, fluid balance, hematocrit, white cell count, white cell differential percentages, platelet count, blood levels of glucose, sodium, and potassium, C reactive protein, lactate, coagulation times, pressure ulcers, shivering, infections and death.

RESULTS

Thirty-one patients with a mean age of 20 months (SD: 39.8) were included in the study. The mean duration of IH was 3.97 days (range: 1 to 11 days). Among the IH effects, there was a significant fall in heart rate, with no changes in SBP, DBP, or diuresis. The blood tests revealed a progressive and significant fall in platelet count and an increase in C reactive protein levels. The fall in hematocrit and glucose and lactate levels was not significant. Positive cultures were detected in 25.8% of the patients during IH, most commonly from the bronchial aspirate (65%).

CONCLUSIONS

Induced hypothermia can be useful in some critically ill children. Tolerance is generally good and there are usually few side effects, which can be controlled through appropriate monitoring.

The role of bystanders during rescue and resuscitation of drowning victims

BACKGROUND

Bystanders make a critical difference in the survival of drowning victims. Little information on their role before arrival of the Emergency Medical Services (EMS) is available in the scientific literature. In a descriptive study, this role is investigated.

METHODS AND RESULTS

We studied 289 rescue reports (1999-2004) available from the Dutch Maatschappij tot Redding van Drenkelingen (Society to Rescue People from Drowning), an organisation that, since 1767, acknowledges awards to bystanders who have contributed to the survival of a drowning victim. There were 138 variables retrieved from these reports. The Utstein Style for Drowning (USFD) was used as a guideline. Of the 26 USFD parameters on victim and scene information, 21 were available for analysis. Eight non-USFD parameters, defined by the authors of this research, were available in >60% of the cases. There were 343 victims, rescued by 503 rescuers. 109 victims were resuscitated by bystanders. Of the 18 victims who first received resuscitation from bystanders and then consequently from pre-hospital professionals, 14 survived. Rescues often occurred in dangerous circumstances: multiple victims (n=90/343), cold or ice-cold water (n=295/341), deep water (n=316/334), swimming to the victims (n=262/376), young age of rescuers (the youngest rescuer was 5 years of age).

CONCLUSIONS

Bystander rescue and resuscitation of drowning victims seems to contribute to a positive outcome. Bystanders are prepared to take responsibility to rescue a drowning victim in spite of significant dangers. The USFD is helpful in understanding the role of bystanders in drowning situations, but may need modification to become more instrumental.

Treatment of severe accidental hypothermia with intermittent hemodialysis

The optimal management of moderate-to-severe hypothermia with hemodynamic instability remains unclear. Although cardiopulmonary bypass offers the most rapid rate of rewarming and has been suggested as the method of choice in the presence of circulatory arrest, there is no evidence to support the use of this highly invasive technique over other rewarming modalities in the absence of circulatory collapse. We report the successful treatment of hemodynamically unstable hypothermia with conventional hemodialysis in a patient with normal renal function, after initial efforts of rewarming using conventional strategies had failed. This case report and review of the literature highlights the advantages and the challenges of using hemodialysis in this setting, and suggests a potential role for hemodialysis in the routine management of moderate-to-severe hypothermia in the absence of circulatory arrest.

The efficacy of rewarming with a portable and percutaneous cardiopulmonary bypass system in accidental deep hypothermia patients with hemodynamic instability

OBJECTIVE

Accidental deep hypothermia (ADH)--a condition in which the core body temperature is less than 28 degrees C--is a medical emergency; the mortality rates for ADH remain high. The efficacy of cardiopulmonary bypass (CPB) rewarming has been proved in ADH patients with cardiopulmonary arrest; however, its efficacy in the ADH patients without cardiopulmonary arrest remains controversial. In our study, we evaluated the efficacy of portable percutaneous cardiopulmonary bypass (PPCPB) for rewarming and providing cardiovascular support in the hemodynamically unstable ADH patients without cardiopulmonary arrest.

METHODS

Between April 2001 and March 2006, we performed a retrospective study at Tokai University, Kanagawa, Japan. We studied 24 ADH patients without cardiopulmonary arrest (male:female ratio, 15:9; mean age, 68.5 +/- 12.9 years) with hemodynamic instability who had not developed intracranial hemorrhage. We evaluated the efficacy of PPCPB rewarming by estimating the mean time of initiation of PPCPB after admission, rewarming speed, the success rate of rewarming, the rate of weaning from PPCPB, the incidence of ventricular fibrillation (Vf) during rewarming, complications associated with PPCPB, mortality rate, and the Glasgow Outcome Scale (GOS) scores of the patients who survived.

RESULTS

The mean time of initiation of PPCPB after admission was 41.9 +/- 7.9 minutes. The rewarming speed was 4.0 +/- 1.5 degrees C/h. A 100% success rate was achieved after the rewarming procedure, whereas the rate of weaning from PPCPB was 91.7%. Vf during rewarming developed in one case; however, electrical defibrillation was possible. No direct complications of PPCPB were observed. The mortality rate was 12.5% (3/24). The GOS scores of the patients who survived were as follows: 5 points, 17 cases; 4 points, 3 cases; and 3 points, 1 case.

CONCLUSION

PPCPB rewarming is a clinically efficacious procedure for rewarming and providing cardiovascular support in hemodynamically unstable ADH patients without cardiopulmonary arrest who have not developed intracranial hemorrhage.

[Management of accidental hypothermia]

Patients with hypothermia are frequently encountered in emergency medicine. Particularly trauma patients, but also other predisposed persons, can be expected to suffer from hypothermia at any time of the year. Therapy focuses not only on symptom-oriented intensive care to stabilize and secure vital functions, but also on rewarming. Even in cases of severe hypothermia with circulatory arrest, therapy can produce excellent results. This paper first gives a brief overview of the typical clinical symptoms of hypothermia, before giving a detailed description of the preclinical and in-hospital management of the hypothermia patient. The various rewarming strategies are the subject of special attention and critical evaluation.

The Osborn wave in accidental hypothermia

Hypothermia is generally defined as a core body temperature less than 35 degrees C (95 degrees F), and is one of the most common environmental emergencies encountered by emergency physicians. A 32-year-old male hunter was admitted to the hospital with altered mental status. He remained unconscious, Glasgow Coma Scale (GCS) score was recorded as 5/15, and pupils were dilated and unreactive. His vital signs showed a heart rate of 48 beats/min, respiratory rate of 10 breaths/min, blood pressure of 95/50 mm Hg, and rectal temperature of 31 degrees C. An electrocardiogram (ECG) was obtained and showed marked sinus bradycardia and J waves. His finger-stick glucose was 85. He was intubated. After 3 h of active rewarming, his temperature was 34 degrees C, and the repeat ECG showed near-complete resolution of the J waves and acceleration of the sinus rate to 68 beats/min. At the same time, emergency head computed tomography (CT) scan showed subarachnoid hemorrhage (SAH) and subdural hemorrhage. The patient died on the third day of admission. In this case we want to indicate that J waves and obtunded state could be due to either SAH or hypothermia, and SAH could have been missed if initial obvious hypothermia had been believed to cause all symptoms.

Kardiopulmonale Reanimation nach Heroinintoxikation und Hypothermie

We present the case of a 21-year-old female drug addict with severe accidental hypothermia (core body temperature 27.5 degrees C) and cardiorespiratory arrest. After successful cardiopulmonary resuscitation the patient was actively internally rewarmed without the use of extracorporal circulation. Although at the first clinical presentation the patient appeared to be dead, an excellent neurological outcome was achieved. This case report reviews the epidemiology, pathophysiology, prognostic markers and the therapeutic approaches of severe hypothermia.

Effects of sympathetic stimulation during cooling on hypothermic as well as posthypothermic hemodynamic function

This experimental study was performed to explore hemodynamic effects of a moderate dose epinephrine (Epi) during hypothermia and to test the hypothesis whether sympathetic stimulation during cooling affects myocardial function following rewarming. Two groups of male Wistar rats (each, n = 7) were cooled to 15 °C, maintained at this temperature for 1 h, and then rewarmed. Group 1 received 1 μg/min Epi, i.v., for 1 h during cooling to 28 °C, a dose known to elevate cardiac output (CO) by approximately 25% at 37 °C. Group 2 served a saline solution control. At 37 °C, Epi infusion elevated CO, left ventricular systolic pressure, maximum rate of left ventricle pressure rise, and mean arterial pressure. During cooling to 28 °C, these variables, with the exception of mean arterial pressure, decreased in parallel to those in the saline solution group. In contrast, in the Epi group, mean arterial pressure remained increased and total peripheral resistance was significantly elevated at 28 °C. Compared with corresponding prehypothermic values, most hemodynamic variables were lowered after 1 h at 15 °C in both groups (except for stroke volume). After rewarming, alterations in hemodynamic variables in the Epi-treated group were more prominent than in saline solution controls. Thus, before cooling, continuous Epi infusion predominantly stimulates myocardial mechanical function, materialized as elevation of CO, left ventricular systolic pressure, and maximum rate of left ventricle pressure rise. Cooling, on the other hand, apparently eradicates central hemodynamic effects of Epi and during stable hypothermia, elevation of peripheral vascular vasopressor effects seem to take over. In contrast to temperature-matched, non-Epi stimulated control rats, a significant depression of myocardial mechanical function occurs during rewarming following a moderate sympathetic stimulus during initial cooling.

Hypothermia: evaluation, electrocardiographic manifestations, and management

Hypothermia-related cases typically occur after exposure to low ambient temperatures; however, numerous cases occur in individuals with no history of exposure to cold environment. Hypothermia is associated with such complications as acidosis, impaired myocardial function, bleeding diathesis, and decreased kidney and liver function. The well-known electrocardiographic manifestations of hypothermia are the presence of J (Osborn) waves, prolonged PR, QRS, and QT intervals, and atrial arrhythmias. The choice of rewarming therapy is based on the degree of hypothermia. The evaluation, electrocardiographic manifestations, and management of hypothermia are reviewed.

Akzidentelle urbane Unterkühlung

In emergency medicine accidental hypothermia (<35 degrees C) is a common epiphenomenon of many medical conditions. In contrast, severe hypothermia (<28 degrees C) occurs very seldom and presents a difficult medical situation. Here we present a female patient with severe urban hypothermia (core temperature of 20.7 degrees C) and circulatory arrest. An overview of the emergency treatment, rewarming strategy with extracorporeal circulation and the clinical course will be given. The survival of the patient and the favorable neurological outcome will be discussed considering the current literature. Due to the paucity of treatment guidelines or clear prognostic criteria of withholding or withdrawing treatment in severe hypothermia, the decision of prolonged resuscitation and rewarming strategy is solely dependent on the individual judgement and medical experience of the physician. The positive clinical outcome which can be gleaned from case reports or single retrospective studies should encourage the emergency physician to selectively rewarm a severe hypothermic patient with extracorporeal circulation under prolonged CPR.

Hypothermia in a surgical intensive care unit

BACKGROUND

Inadvertent hypothermia is not uncommon in the immediate postoperative period and it is associated with impairment and abnormalities in various organs and systems that can lead to adverse outcomes. The aim of this study was to estimate the prevalence, the predictive factors and outcome of core hypothermia on admission to a surgical ICU.

METHODS

All consecutive 185 adult patients who underwent scheduled or emergency noncardiac surgery admitted to a surgical ICU between April and July 2004 were admitted to the study. Tympanic membrane core temperature (Tc) was measured before surgery, on arrival at ICU and every two hours until 6 hours after admission. The following variables were also recorded: age, sex, body weight and height, ASA physical status, type of surgery, magnitude of surgical procedure, anesthesia technique, amount of intravenous fluids administered during anesthesia, use of temperature monitoring and warming techniques, duration of the anesthesia, ICU length of stay, hospital length of stay and SAPS II score. Patients were classified as either hypothermic (Tc < or = 35 degrees C) or normothermic (Tc> 35 degrees C). Univariate analysis and multiple regression binary logistic with an odds ratio (OR) and its 95% Confidence Interval (95%CI) were used to compare the two groups of patients and assess the relationship between each clinical predictor and hypothermia. Outcome measured as ICU length of stay and mortality was also assessed.

RESULTS

Prevalence of hypothermia on ICU admission was 57.8%. In univariate analysis temperature monitoring, use of warming techniques and higher previous body temperature were significant protective factors against core hypothermia. In this analysis independent predictors of hypothermia on admission to ICU were: magnitude of surgery, use of general anesthesia or combined epidural and general anesthesia, total intravenous crystalloids administrated and total packed erythrocytes administrated, anesthesia longer than 3 hours and SAPS II scores. In multiple logistic regression analysis significant predictors of hypothermia on admission to the ICU were magnitude of surgery (OR 3.9, 95% CI, 1.4-10.6, p = 0.008 for major surgery; OR 3.6, 95% CI, 1.5-9.0, p = 0.005 for medium surgery), intravenous administration of crystalloids (in litres) (OR 1.4, 95% CI, 1.1-1.7, p = 0.012) and SAPS score (OR 1.0, 95% CI 1.0-1.7, p = 0.014); higher previous temperature in ward was a significant protective factor (OR 0.3, 95% CI 0.1-0.7, p = 0.003). Hypothermia was neither a risk factor for hospital mortality nor a predictive factor for staying longer in ICU.

CONCLUSION

The prevalence of patient hypothermia on ICU arrival was high. Hypothermia at time of admission to the ICU was not an independent factor for mortality or for staying longer in ICU.