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- Seventy-two hours of mild hypothermia after cardiac arrest is associated with a lowered inflammatory response during rewarming in a prospective observational study. [JOURNAL ARTICLE]
- Crit Care 2014 Oct 11; 18(5):546.
IntroductionWhole-body ischemia and reperfusion trigger a systemic inflammatory response. This study analyzed the effect of temperature on the inflammatory response in patients treated with prolonged mild hypothermia after cardiac arrest.MethodsTen comatose patients with return of spontaneous circulation (ROSC) after pulseless electrical activity (PEA)/asystole or prolonged ventricular fibrillation were treated with mild therapeutic hypothermia for 72 hours after admission to a tertiary care university hospital. On admission and at 12, 24, 36, 48, 72, 96 and 114 h temperature was measured and blood samples were taken from the arterial catheter. Proinflammatory interleukin (IL)-6 and anti-inflammatory (IL-10) cytokines and chemokines (IL-8 and monocyte chemotactic protein1 (MCP-1)), the intercellular adhesion molecule 1 (ICAM-1), and complement activation products (C1rs-C1-INH, C4bc, C3bPBb, C3bc and TCC) were measured. Changes over time were analyzed with the repeated measures test for non-parametric data. The Dunn's Multiple Comparison Test was used for comparison of individual time points.ResultsMedian temperature at the start of the study was 34.3°C (33.4 to 35.2) and was maintained between 32 to 34°C for 72 h. All patients were passively rewarmed after 72 h from 33.7°C (33.1 to 33.9) at 72 h to 38.0°C (37.5 to 38.1) at 114 h after admission (P <0.001). In general, the cytokines and chemokines remained stable during hypothermia and decreased during rewarming, whereas complement activation was suppressed during the whole hypothermia period and increased modestly during rewarming.ConclusionsProlonged hypothermia possibly blunts the inflammatory response after rewarming in patients after cardiac arrest. Complement activation was low during the whole hypothermia period, indicating that complement activation is highly temperature sensitive also in vivo. Since inflammation is a strong mediator of secondary brain injury, a blunted pro-inflammatory response after rewarming may be beneficial.
- Severe Accidental Hypothermia Center. [JOURNAL ARTICLE]
- Eur J Emerg Med 2014 Oct 9.
Hypothermic patients may be rewarmed using passive or active techniques. In case of severe accidental hypothermia (temperature<28°C) and stage III/IV according to the Swiss Staging System, standard methods might not be effective and aggressive treatment is needed. Extracorporeal membrane oxygenation (ECMO) has proved to be both effective and safe in such cases. The Department of Anesthesiology and Intensive Care, John Paul II Hospital, Cracow, Poland, established the Severe Accidental Hypothermia Center, which provides 24 h on-call to consult and accept patients who need ECMO implantation for profound hypothermia rewarming. Our center is so far the only one in Poland and can accept patients from south-east Poland. Most importantly, it collaborates with all prehospital medical services, namely, with 115 Ambulances, Polish Medical Air Rescue, Mountain Rescue Services, and all 28 Emergency Departments in the area. Severe Accidental Hypothermia Center is a solution for advanced treatment of patients with accidental hypothermia requiring ECMO implantation.
- Does close temperature regulation affect surgical site infection rates? [Journal Article, Review]
- Adv Surg 2014.:65-76.
The argument for close temperature control, to which regulatory bodies have held health systems in an effort to reduce the burden of hospital-acquired infections, is not fully supported by current evidence. The literature is complex on the topic, and overinterpretation of historical data supporting close temperature regulation does not preclude an important recognition of these early works' contribution to high-quality surgical care. Avoidance of hypothermia through the regular use of active rewarming should be a routine part of safe surgical care. The biochemical basis of emphasizing temperature regulation is sound, and ample evidence shows the frank physiologic derangements seen when biological processes occur at suboptimal temperature. It is also recognized that patients tend to do better when warmed during the perioperative period, suggesting that warming devices are an important and essential adjunct to good perioperative care. Clinicians, researchers, and policymakers must be careful in how they apply these well-supported findings to process metrics in an era of limited resources with increasingly stringent quality guidelines and outcomes measures. Discrete temperature targets in current measures are not supported by the existing literature. Not only do these targets artificially anchor clinicians to temperature values with an inadequate scientific basis but they demand intensive resources from health institutions that could potentially be better used on quality requirements with stronger evidence of their ultimate effect on patient care.
- Effect of Head and Face Insulation on Cooling Rate During Snow Burial. [JOURNAL ARTICLE]
- Wilderness Environ Med 2014 Sep 30.
Avalanche victims are subjected to a number of physiological stressors during burial. We simulated avalanche burial to monitor physiological data and determine whether wearing head and face insulation slows cooling rate during snow burial. In addition, we sought to compare 3 different types of temperature measurement methods.Nine subjects underwent 2 burials each, 1 with head and face insulation and 1 without. Burials consisted of a 60-minute burial phase followed by a 60-minute rewarming phase. Temperature was measured via 3 methods: esophageal probe, ingestible capsule, and rectal probe.Cooling and rewarming rates were not statistically different between the 2 testing conditions when measured by the 3 measurement methods. All temperature measurement methods correlated significantly.Head and face insulation did not protect the simulated avalanche victim from faster cooling or rewarming. Because the 3 temperature measurement methods correlated, the ingestible capsule may provide an advantageous noninvasive method for snow burial and future hypothermia studies if interruptions in data transmission can be minimized.
- Cardiovascular effects of levosimendan during rewarming from hypothermia in rat. [JOURNAL ARTICLE]
- Cryobiology 2014 Sep 30.
Previous research aimed at ameliorating hypothermia-induced cardiac dysfunction has shown that inotropic drugs, that stimulate the cAMP, - PKA pathway via the sarcolemmal β-receptor, have a decreased inotropic effect during hypothermia. We therefore wanted to test whether levosimendan, a calcium sensitizer and dose-dependent phosphodiesterase 3 (PDE3) inhibitor, is able to elevate stroke volume during rewarming from experimental hypothermia.A rat model designed for circulatory studies during experimental hypothermia (4 h at 15°C) and rewarming was used. The following three groups were included: 1) A normothermic group receiving levosimendan, 2) a hypothermic group receiving levosimendan the last hour of stable hypothermia and during rewarming, and 3) a hypothermic placebo control group. Hemodynamic variables were monitored using a Millar conductance catheter in the left ventricle (LV), and a pressure transducer connected to the left femoral artery. In order to investigate the level of PKA stimulation by PDE3 inhibition, myocardial Ser23/24-cTnI phosphorylation was measured using western-blot.After rewarming, stroke volume (SV), cardiac output (CO) and preload recruitable stroke work (PRSW) were restored to within pre-hypothermic values in the levosimendan-treated animals. Compared to the placebo group after rewarming, SV, CO, PRSW, as well as levels of Ser23/24-cTnI phosphorylation, were significantly higher in the levosimendan-treated animals.The present data shows that levosimendan ameliorates hypothermia-induced systolic dysfunction by elevating SV during rewarming from 15°C. Inotropic treatment during rewarming from hypothermia in the present rat model is therefore better achieved through calcium sensitizing and PDE3 inhibition, than β-receptor stimulation.
- Electroencephalography (EEG) for neurological prognostication after cardiac arrest and targeted temperature management; rationale and study design. [JOURNAL ARTICLE]
- BMC Neurol 2014 Aug 16; 14(1):159.
Electroencephalography (EEG) is widely used to assess neurological prognosis in patients who are comatose after cardiac arrest, but its value is limited by varying definitions of pathological patterns and by inter-rater variability. The American Clinical Neurophysiology Society (ACNS) has recently proposed a standardized EEG-terminology for critical care to address these limitations.In the TTM-trial, 399 post cardiac arrest patients who remained comatose after rewarming underwent a routine EEG. The presence of clinical seizures, use of sedatives and antiepileptic drugs during the EEG-registration were prospectively documented.A well-defined terminology for interpreting post cardiac arrest EEGs is critical for the use of EEG as a prognostic tool.The TTM-trial is registered at ClinicalTrials.gov (NCT01020916).
- Cardiac condition during cooling and rewarming periods of therapeutic hypothermia after cardiopulmonary resuscitation. [Journal Article]
- BMC Anesthesiol 2014.:78.
Hypothermia has been used in cardiac surgery for many years for neuroprotection. Mild hypothermia (MH) [body temperature (BT) kept at 32-35°C] has been shown to reduce both mortality and poor neurological outcome in patients after cardiopulmonary resuscitation (CPR). This study investigated whether patients who were expected to benefit neurologically from therapeutic hypothermia (TH) also had improved cardiac function.The study included 30 patients who developed in-hospital cardiac arrest between September 17, 2012, and September 20, 2013, and had return of spontaneous circulation (ROSC) following successful CPR. Patient BTs were cooled to 33°C using intravascular heat change. Basal BT, systolic artery pressure (SAP), diastolic artery pressure (DAP), mean arterial pressure (MAP), heart rate, central venous pressure, cardiac output (CO), cardiac index (CI), global end-diastolic volume index (GEDI), extravascular lung water index (ELWI), and systemic vascular resistance index (SVRI) were measured at 36°C, 35°C, 34°C and 33°C during cooling. BT was held at 33°C for 24 hours prior to rewarming. Rewarming was conducted 0.25°C/h. During rewarming, measurements were repeated at 33°C, 34°C, 35°C and 36°C. A final measurement was performed once patients spontaneously returned to basal BT. We compared cooling and rewarming cardiac measurements at the same BTs.SAP values during rewarming (34°C, 35°C and 36°C) were lower than during cooling (P < 0.05). DAP values during rewarming (basal temperature, 34°C, 35°C and 36°C) were lower than during cooling. MAP values during rewarming (34°C, 35°C and 36°C) were lower than during cooling (P < 0.05). CO and CI values were higher during rewarming than during cooling. GEDI and ELWI did not differ during cooling and rewarming. SVRI values during rewarming (34°C, 35°C, 36°C and basal temperature) were lower than during cooling (P < 0.05).To our knowledge, this is the first study comparing cardiac function at the same BTs during cooling and rewarming. In patients experiencing ROSC following CPR, TH may improve cardiac function and promote favorable neurological outcomes.
- Torpor and hypothermia: reversed hysteresis of metabolic rate and body temperature. [JOURNAL ARTICLE]
- Am J Physiol Regul Integr Comp Physiol 2014 Sep 24.:ajpregu.00214.2014.
Regulated torpor and unregulated hypothermia are both characterized by substantially reduced body temperature (Tb¬) and metabolic rate (MR), but they differ physiologically. Although the remarkable, medically interesting adaptations accompanying torpor (e.g., tolerance for cold and ischemia, absence of reperfusion injury and disuse atrophy) often do not apply to hypothermia in homeothermic species such as humans, the terms "torpor" and "hypothermia" are often used interchangeably in the literature. To determine how these states differ functionally and to provide a reliable diagnostic tool for differentiating between these two physiologically distinct states, we examined the interrelations between Tb and MR in a mammal (Sminthopsis macroura) undergoing a bout of torpor with those of the hypothermic response of a similar-sized juvenile rat (Rattus norvegicus). Our data show that under similar thermal conditions, 1) cooling rates differ substantially (~5-fold) between the two states; 2) minimum MR is ~7-fold higher during hypothermia than during torpor despite a similar Tb; 3) rapid, endogenously fuelled rewarming occurs in torpor but not hypothermia; and 4) the hysteresis between Tb/MR during warming and cooling proceeds in opposite directions in torpor and hypothermia. We thus demonstrate clear diagnostic physiological differences between these two states that can be used experimentally to confirm whether torpor or hypothermia has occurred. Furthermore, the data can clarify the results of studies investigating the ability of physiological or pharmacological agents to induce torpor. Consequently, we recommend using the terms "torpor" and "hypothermia" in ways that are consistent with the underlying regulatory differences between these two physiological states.
- Therapeutic Hypothermia (Different Depths, Durations, and Rewarming Speeds) for Acute Ischemic Stroke: A Meta-analysis. [JOURNAL ARTICLE]
- J Stroke Cerebrovasc Dis 2014 Sep 16.
Whether therapeutic hypothermia benefits patients with acute ischemic stroke (AIS) remains controversial. The aim of this study was to evaluate the efficacy and safety of the different depths, durations, and rewarming speeds of therapeutic hypothermia for AIS.The MEDLINE (OVID), EMBASE, and Cochrane Central Register of Controlled Trials were systematically searched for randomized controlled trials (RCTs) of therapeutic hypothermia for AIS from the inception of the databases to October 2013. After data extraction and quality assessment, a meta-analysis was performed using RevMan 5.1.A total of 6 RCTs involving 252 AIS patients were eligible for the meta-analysis. Subanalyses stratified by depth, duration, and rewarming speed of therapeutic hypothermia were also performed. Our results showed that therapeutic hypothermia was associated with an increased risk of pneumonia (risk ratio = 3.30, 95% CI 1.48-7.34; P = .003, P for heterogeneity = .91, I(2) = 0%). No significant difference was observed between the 2 groups in terms of neurologic outcomes, mortality, and other complications including symptomatic or fatal intracranial hemorrhage, deep vein thrombosis, and atrial fibrillation.These limited data suggest that therapeutic hypothermia does not significantly improve stroke outcomes and may lead to higher rates of pneumonia. Multicenter RCTs with larger samples are needed to confirm the current findings.
- [Case report - Hemodynamic variables of a deep hypothermic patient over the period of external rewarming]. [English Abstract, Journal Article]
- Anasthesiol Intensivmed Notfallmed Schmerzther 2014 Sep; 49(9):514-9.
Deep accidental hypothermia is a very rare emergency, most of these patients die despite of immediate and adaequate therapy. We report on a hypothermic patient who was in a stable hemodynamic condition and breathing spontaneously at a temperature of 25.5°C. He was rewarmed with non-invasive methods. We describe and discuss the hemodynamic variables of an advanced monitoring during the time of external rewarming.