Drop In Core Body Temperature Research Articles

Interventions for treating inadvertent postoperative hypothermia.

Inadvertent postoperative hypothermia (a drop in core body temperature to below 36°C) occurs as an effect of surgery when anaesthetic drugs and exposure of the skin for long periods of time during surgery result in interference with normal temperature regulation. Once hypothermia has occurred, it is important that patients are rewarmed promptly to minimise potential complications. Several different interventions are available for rewarming patients. To estimate the effectiveness of treating inadvertent perioperative hypothermia through postoperative interventions to decrease heat loss and apply passive and active warming systems in adult patients who have undergone surgery. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 2), MEDLINE (Ovid SP) (1956 to 21 February 2014), EMBASE (Ovid SP) (1982 to 21 February 2014), the Institute for Scientific Information (ISI) Web of Science (1950 to 21 February 2014) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL), EBSCO host (1980 to 21 February 2014), as well as reference lists of articles. We also searched www.controlled-trials.com and www.clincialtrials.gov. Randomized controlled trials of postoperative warming interventions aiming to reverse hypothermia compared with control or with each other. Three review authors identified studies for inclusion in this review. One review author extracted data and completed risk of bias assessments; two review authors checked the details. Meta-analysis was conducted when appropriate by using standard methodological procedures as expected by The Cochrane Collaboration. We included 11 trials with 699 participants. Ten trials provided data for analysis. Trials varied in the numbers and types of participants included and in the types of surgery performed. Most trials were at high or unclear risk of bias because of inappropriate or unclear randomization procedures, and because blinding of assessors and participants generally was not possible. This may have influenced results, but it is unclear how the results may have been influenced. Active warming was found to reduce the mean time taken to achieve normothermia by about 30 minutes in comparison with use of warmed cotton blankets (mean difference (MD) -32.13 minutes, 95% confidence interval (CI) -42.55 to -21.71; moderate-quality evidence), but no significant difference in shivering was noted. Active warming was found to reduce mean time taken to achieve normothermia by almost an hour and a half in comparison with use of unwarmed cotton blankets (MD -88.86 minutes, 95% CI -123.49 to -54.23; moderate-quality evidence), and people in the active warming group were less likely to shiver than those in the unwarmed cotton blanket group (Relative Risk=0.61 95% CI= 0.42 to 0.86; low quality evidence). There was no effect on mean temperature difference in degrees celsius at 60 minutes (MD=0.18°C, 95% CI=-0.10 to 0.46; moderate quality evidence), and no data were available in relation to major cardiovascular complications. Forced air warming was found to reduce time taken to achieve normothermia by about one hour in comparison to circulating hot water devices (MD=-54.21 minutes 95% CI= -94.95, -13.47). There was no statistically significant difference between thermal insulation and cotton blankets on mean time to achieve normothermia (MD =-0.29 minutes, 95% CI=-25.47 to 24.89; moderate quality evidence) or shivering (Relative Risk=1.36 95% CI= 0.69 to 2.67; moderate quality evidence), and no data were available for mean temperature difference or major cardiovascular complications. Insufficient evidence was available about other comparisons, adverse effects or any other secondary outcomes. Active warming, particularly forced air warming, appears to offer a clinically important reduction in mean time taken to achieve normothermia (normal body temperature between 36°C and 37.5°C) in patients with postoperative hypothermia. However, high-quality evidence on other important clinical outcomes is lacking; therefore it is unclear whether active warming offers other benefits and harms. High-quality evidence on other warming methods is also lacking; therefore it is unclear whether other rewarming methods are effective in reversing postoperative hypothermia.

Effects of Alcohol on Athletic Performance

Background: Alcohol is a substance that is consumed widely around the world. There are different interpretations regarding the effects of alcohol on athletic performance. Today, alcohol is introduced as a contributing factor for increasing athletic performance by some sport clubs. Methods: The purpose of this article is to investigate the effects of alcohol on athletic performance. PubMed, Scopus, Medline, and textbooks were reviewed. Results: The effect of alcohol is different according to the dose, individual habits and duration of exercise. The main mechanisms of the effect of alcohol on athletic performance are: Inadequate synthesis of hepatic glucose and impaired hepatic gluconeogenesis, even at low dose; alcohol can cause hypoglycemia and impair performance in prolonged exercise. Impaired regulation of body temperature during exercise is also an effect of alcohol. The vasodilator effect of alcohol cause a drop in core body temperature and impair athletic performance. Alcohol causes dehydration due to its diuretic effect. So, alcohol is not a good choice for rehydration after an exercise. Impairment of glycogen re-synthesis after exercise is due to alcohol interaction with glycogen synthesis in the liver. Psychological effects of alcohol impair reaction time, fine motor control, decision making, judgment and balance. Conclusion: The result of this review does not show a positive effect of alcohol on athletic performance.

Web-based hypothermia information: a critical assessment of Internet resources and a comparison to peer-reviewed literature

Hypothermia is a medical condition characterized by a drop in core body temperature, and it is a considerable source of winter weather-related vulnerability in mid-/high-latitude areas. Heat vulnerability research, including assessments of internet-based resources, is more thoroughly represented in the peer-reviewed literature than cold-related vulnerability research. This study was undertaken to summarize available web-based hypothermia information, and then determine its scientific validity compared to the peer-reviewed literature. This research takes a similar approach used by Hajat et al. for web-based heat vulnerability research, and utilizes this framework to assess hypothermia information found on the internet. Hypothermia-related search terms were used to obtain websites containing hypothermia information, and PubMed (medical literature search engine) and Google Scholar were used to identify peer-reviewed hypothermia literature. The internet information was aggregated into categories (vulnerable populations, symptoms, prevention), which were then compared to the hypothermia literature to determine the scientific validity of the web-based guidance. The internet information was assigned a Strength of Recommendation Taxonomy (SORT) grade (developed by the American Academy of Family Practitioners) of A, B, or C based on the peer-reviewed evidence. Overall, 25 different pieces of guidance within the three categories were identified on 49 websites. Guidance concerning hypothermia symptoms most frequently appeared on websites, with six symptoms appearing on 50% or greater of websites. No piece of guidance within the vulnerable population categories appeared on greater than 60% of the websites, and prevention-related guidance was characterized by varied SORT grades. Hypothermia information on the internet was not entirely congruent with the information within the peer-reviewed medical literature. Several suggestions for improving web-based hypothermia resources include clearly listing sources for users to see and eliminating guidance with lower SORT grades and replacing with evidence-based information.

De Novo delayed onset hypothermia secondary to therapeutic doses of risperidone in bipolar affective disorder

The commonly reported side effects related to risperidone include dizziness, nausea, weight gain, sleep disturbances, and sexual dysfunction. A rather rare and very much less documented side effect of risperidone is hypothermia: traditionally defined as a drop in core body temperature below 35°C (95°F). We report a case of a 75-year-old woman who had been treated for bipolar affective disorder for nearly 3 years with risperidone went on to develop hypothermia which was reversed with the withdrawal of the offending drug. This case is unique as it reported a rare but potentially serious side effect occurring after a prolonged administration of risperidone contrary to the previous reports in which hypothermia occurred only a few hours or days after the administration of risperidone and occurred in a patient who was diagnosed as having bipolar affective disorder as opposed to schizophrenia, the most common psychiatric disorder associated with previously reported hypothermia. The authors would like to emphasize the importance of this idiosyncratic potentially life-threatening adverse effect of risperidone-induced hypothermia to all clinicians, which occurs regardless of the duration of drug intake, in order to help them identify the condition early and treat it effectively.

Drugs that prevent mouse sleep also block light-induced locomotor suppression, circadian rhythm phase shifts and the drop in core temperature

Exposure of mice to a brief light stimulus during their nocturnal active phase induces several simultaneous behavioral or physiological responses, including circadian rhythm phase shifts, a drop in core body temperature (Tc), suppression of locomotor activity and sleep. Each response is triggered by light, endures for a relatively fixed interval and does not require additional light for expression. The present studies address the ability of the psychostimulant drugs, methamphetamine (MA), modafinil (MOD) or caffeine (CAF), to modify the light-induced responses. Drug or vehicle (VEH) was injected at CT11 into constant dark-housed mice then exposed to 5-min 100μW/cm2 light or no light at CT13. Controls (VEH/Light) showed approximately 60-min phase delays. In contrast, response was substantially attenuated by each drug (only 12–15min delays). Under a 12-h light:12-h dark (LD12:12) photoperiod, VEH/light-treated mice experienced a Tc drop of about 1.3°C coincident with locomotor suppression and both effects were abolished by drug pre-treatment. Each drug elevated activity during the post-injection interval, but there was also evidence for CAF-induced hypoactivity in the dark prior to the photic test stimulus. CAF acutely elevated Tc; MA acutely lowered it, but both drugs reduced Tc during the early dark (ZT12.5–ZT13). The ability of the psychostimulant drugs to block the several effects of light exposure is not the result of drug-induced hyperactivity. The results raise questions concerning the manner in which drugs, activity, sleep and Tc influence behavioral and physiological responses to light.

Robotic Partial Nephrectomy with Cold Ischemia and On-clamp Tumor Extraction: Recapitulating the Open Approach

We describe a reproducible technique for achieving cold ischemia with intraoperative tumor assessment during robotic partial nephrectomy (RPN) that recapitulates the open approach: intracorporeal cooling and extraction (ICE).A total of seven patients underwent the ICE modification of RPN by transperitoneal (n=5) and retroperitoneal (n=2) approaches. A Gelpoint access port was used for the camera and assistant ports. Following hilar clamping, ice slush was introduced through the Gelpoint via syringes and applied over the kidney surface. The excised tumor was immediately extracted through the Gelpoint, allowing gross margin assessment by pathology during the renorrhaphy.RPN was achieved in all cases with successful introduction of ice slush and tumor extraction while on clamp. Median RENAL nephrometry score was 8 (range: 6–10), and there was one solitary kidney. Mean cold ischemia time was 19.6min (range: 8–37) and mean estimated blood loss was 296.4ml (range: 50–1000). Renal parenchymal temperatures <16°C were achieved within 7min of cold ischemia and there was no drop in core body temperature >0.5°C during any procedures. Intraoperative assessment of the excised tumor showed adequate gross margins in all cases and final pathology confirmed negative surgical margins.

Lysostaphin Reduces the Production of Inflammatory Cytokines in Staphylococcus aureus Challenged Mice, and Prevents Systemic Shock

Lysostaphin is being developed as a treatment for serious staphylococcal infections. Mice challenged with S. aureus produce inflammatory cytokines including, TNF-� and IL-6, and over-production of these cytokines can lead to shock and contribute to the lethality of staphylococcal infections. Two major components of the staphylococcal cell wall, peptidoglycan and lipoteichoic acid, are known to synergize to induce shock and organ failure in animal models, and we wished to determine whether the rapid lysostaphin-mediated degradation of peptidoglycan during treatment of systemic S. aureus infection could affect shock-associated parameters. We found that lysostaphin treatment of S. aureus-infected mice, which reduces bacteremia and organ infection, also reduced the serum levels of inflammatory cytokines and reversed the symptoms of S. aureus-induced shock. We compared the cytokine response of mice challenged with S. aureus to that of mice challenged with S. aureus and then treated with lysostaphin or nafcillin. Lysostaphin-treated mice, as compared with untreated mice or nafcillin-treated mice, had a blunted cytokine responses to S. aureus challenge. Core body temperature was used as a real time indicator for systemic shock in mice. Mice infected with S. aureus demonstrated a rapid drop in core body temperature, which was reversed by lysostaphin treatment. These studies demonstrated that lysostaphin treatment did not contribute to the induction of shock by rapidly releasing staphylococcal cell wall components, but rather it blunted the inflammatory cytokine response and ameliorated shock related symptoms. Keyword: S. aureus, lysostaphin, shock, cytokine release.

Possible long-acting risperidone-induced hypothermia precipitating phenytoin toxicity in an elderly patient

Thermodysregulation, including hypothermia, is recognized as a potential adverse effect secondary to atypical antipsychotics. We report the first known case of hypothermia possibly associated with long-acting risperidone depot injection, precipitating further adverse events secondary to supratherapeutic phenytoin concentrations. A 75-year-old African-American female presented as a transfer from an outpatient psychiatric center with hypothermia (35·1 °C), bradycardia, altered mental status and a series of witnessed tonic-clonic seizures. The patient was discovered to be profoundly neutropenic (absolute neutrophil count = 266 × 10(9) /L) and a corrected phenytoin concentration was 147·708 μm. During the 3 months preceding admission, phenytoin dosing was stable and consecutive therapeutic concentrations were documented. The only recent change in medication regimen was a switch from oral risperidone to the long-acting injectable formulation. Upon discontinuation of the risperidone and phenytoin, the patient's mental status and laboratory abnormalities returned to baseline. The patient did not experience additional seizure activity. This unintentional significant drop in core body temperature may have resulted in altered metabolism of phenytoin leading to supratherapeutic concentrations and subsequent tonic-clonic seizures, bradycardia and neutropenia. Low core body temperatures can alter the pharmacokinetic profiles of hepatically metabolized medications, prompting careful patient assessment especially in those receiving medications with a narrow-therapeutic index. Hypothermia should be recognized as a potential adverse event with the long-acting injectable formulation of risperidone.

Redefining tissue engineering for nanomedicine in ophthalmology

Working at the nanoscale means to completely rethink how to approach engineering in the body in general and in the eye in particular. In nanomedicine, tissue engineering is the ability to influence an environment either by adding, subtracting or manipulating that environment to allow it to be more conducive for its purpose. The goal is to function at the optimum state, or to return to that optimum state. Additive tissue engineering replaces cells or tissue, or tries to get something to grow that is no longer there. Arrestive tissue engineering tries to stop aberrant growth which, if left uncontrolled, would result in a decrease in function. Nano delivery of therapeutics can perform both additive and arrestive functions influencing the environment either way, depending on the targeting. By manipulating the environment at the nanoscale, the rate and distribution of healing can be controlled. It infers that potential applications of nanomedicine in ophthalmology include procedures, such as corneal endothelial cell transplantation, single retinal ganglion cell repair, check of retinal ganglion cell viability, building of nanofibre scaffolds, such as self-assembling peptides, to create a scaffold-like tissue-bridging structure to provide a framework for axonal regeneration in the case of optic nerve reconnection or eye transplantation, and ocular drug delivery. Examples of potential arrestive therapies include gene-related treatment modalities to inhibit intraocular neovascularization and to block retinal cell apoptosis. Looking towards the future, this review focuses on how nanoscale tissue engineering can be and is being used to influence that local environment.

Concurrent Blockade of Platelet Activating Factor and Histamine Prevents Life-threatening Peanut-induced Anaphylactic Reactions

RATIONALE: Food anaphylaxis is a life-threatening systemic allergic reaction. Fatality registries place peanut as the most common culprit of fatal reactions in North America. Since prophylaxis and treatment have advanced little in recent years, it is imperative to evaluate novel therapies. Here, we have investigated the impact of blocking mediators of anaphylaxis in a mouse model of peanut-induced anaphylaxis (PIA).METHODS: Mice were sensitized with peanut protein and cholera toxin orally for four weeks. One week following the last sensitization, separate groups of mice were treated with either a 5-lypoxygenase inhibitor, a platelet activating factor receptor (PAF-R) antagonist, histamine receptor antagonists, or a PAF-R antagonist along with histamine receptor antagonists (combination therapy) prior to peanut challenge.RESULTS: Peanut challenge resulted in severe (clinical score ∼3.5/5 and ∼7 °C-drop in core body temperature) and prolonged (up to 24 h) anaphylaxis which is largely mediated by mast cells via both IgE and IgG1. Interestingly, treatment targeting either leukotrienes or histamine alone had no beneficial effects. Conversely, PAF antagonism prevented life-threatening reactions (clinical score ∼2 and ∼4°C-drop in body temperature) and allowed faster recovery (83% PAF-treated vs. 43% untreated mice recovered within 120 min after challenge) from PIA; even greater benefit was achieved with combination therapy which, in addition, led to a substantial decrease in vascular leakage and release of vasoactive mediators.CONCLUSIONS: Concomitant blockade of PAF and histamine markedly lessens the severity and duration of peanut-induced anaphylactic reactions and, thus, may represent a life-saving therapy for peanut and, likely, other food-induced anaphylaxis. RATIONALE: Food anaphylaxis is a life-threatening systemic allergic reaction. Fatality registries place peanut as the most common culprit of fatal reactions in North America. Since prophylaxis and treatment have advanced little in recent years, it is imperative to evaluate novel therapies. Here, we have investigated the impact of blocking mediators of anaphylaxis in a mouse model of peanut-induced anaphylaxis (PIA). METHODS: Mice were sensitized with peanut protein and cholera toxin orally for four weeks. One week following the last sensitization, separate groups of mice were treated with either a 5-lypoxygenase inhibitor, a platelet activating factor receptor (PAF-R) antagonist, histamine receptor antagonists, or a PAF-R antagonist along with histamine receptor antagonists (combination therapy) prior to peanut challenge. RESULTS: Peanut challenge resulted in severe (clinical score ∼3.5/5 and ∼7 °C-drop in core body temperature) and prolonged (up to 24 h) anaphylaxis which is largely mediated by mast cells via both IgE and IgG1. Interestingly, treatment targeting either leukotrienes or histamine alone had no beneficial effects. Conversely, PAF antagonism prevented life-threatening reactions (clinical score ∼2 and ∼4°C-drop in body temperature) and allowed faster recovery (83% PAF-treated vs. 43% untreated mice recovered within 120 min after challenge) from PIA; even greater benefit was achieved with combination therapy which, in addition, led to a substantial decrease in vascular leakage and release of vasoactive mediators. CONCLUSIONS: Concomitant blockade of PAF and histamine markedly lessens the severity and duration of peanut-induced anaphylactic reactions and, thus, may represent a life-saving therapy for peanut and, likely, other food-induced anaphylaxis.

Cold nebulization used to prevent heat loss during laparoscopic surgery: an experimental study in pigs

Prolonged abdominal laparoscopy is responsible for a significant drop in core body temperature. Various modifications of the conditioning for the insufflating carbon dioxide (CO(2)) to prevent the specific hypothermia related to the insufflated gas have been tested. This study aimed to investigate the effects on core temperature of insufflation with unheated humidified CO(2) using the Aeroneb system compared with the use of standard gas and gas made hot and wet using a warming and humidifying system (Pall system). A prospective four-session study was conducted to investigate a homogeneous group of four pigs. After inducation of general anesthesia, all the animals were treated successively with the following protocols in a randomized order at 8-day intervals: control (no pneumoperitoneum), standard (unheated, unhumidified CO(2)), Aeroneb (unheated, humidified CO(2) by cold nebulization), and Pall (heated, humidified CO(2)). The core temperature of the animals was recorded every 10 min. Analysis of variance (ANOVA) confirmed a difference between the insufflation conditions in the evolution of temperature over time (p = 0.004). The method of contrast showed the following results. After 30 min, the core temperature of the Aeroneb group fell significantly less than that of the standard group (p = 0.036). After 100 min, the core temperature of the Pall group fell significantly less than that of the standard group (p = 0.024). After 80 min, the core temperature of the standard group fell significantly more than that of the control group (p = 0.035). In the Aeroneb group, the core temperature dropped less than in the Pall and control groups, but the difference did not reach statistical significance. Cold humidification of insufflating CO(2) prevents heat loss associated with pneumoperitoneal insufflation at least as efficaciously as warmed humidification of the gas.

Impact of CD40 Ligand, B Cells, and Mast Cells in Peanut-Induced Anaphylactic Responses

The effector immune mechanisms underlying peanut-induced anaphylaxis remain to be fully elucidated. We investigated the relative contribution of Igs, mast cells (MCs), and FcepsilonRI in the elicitation of anaphylaxis in a murine model. Assessment of peanut hypersensitivity reactions was performed clinically and biologically. Our data show that wild-type (WT; C57BL/6 strain) mice consistently developed severe anaphylaxis (median clinical score: 3.5/5), an approximately 8 degrees C drop in core body temperature, and significantly increased plasma levels of histamine and leukotrienes. CD40 ligand- and B cell-deficient mice presented evidence of allergic sensitization as demonstrated by production of Th2-associated cytokines by splenocytes and a late-phase inflammatory response that were both indistinguishable to those detected in WT mice. However, CD40 ligand- and B cell-deficient mice did not exhibit any evidence of anaphylaxis. Our data also show that MC-deficient (Kit(W)/Kit(W-v)) mice did not suffer, unlike their littermate controls, anaphylactic reactions despite the fact that serum levels of peanut-specific Igs were similarly elevated. Finally, FcepsilonRI-deficient mice experienced anaphylactic responses although to a significantly lesser degree than those observed in WT mice. Thus, these data demonstrate that the presence of peanut-specific Abs along with functional MCs comprise a necessary and sufficient condition for the elicitation of peanut-induced anaphylaxis. That the absence of FcepsilonRI prevented the development of anaphylaxis only partially insinuates the contribution of an IgE-independent pathway, and suggests that strategies to impair MC degranulation may be necessary to improve the efficacy of anti-IgE therapy.

The effects of galanin-like peptide on energy balance, body temperature and brain activity in the mouse and rat are independent of the GALR2/3 receptor.

Galanin-like peptide (GALP) is a neuropeptide that is thought to act on the galanin receptors GALR1, GALR2 and GALR3. In rats, i.c.v. injection of GALP has dichotomous actions on energy balance, stimulating feeding over the first hour, but reducing food intake and body weight at 24 h, as well as causing an increase in core body temperature. In mice, GALP only induces an anorexic action, and its effects on core body temperature are unknown. One aim of the present study was to determine the effects of GALP on core body temperature in mice. Intracerebroventricular injection of GALP into conscious mice had no effect on feeding over 1 h, but caused a significant reduction in food intake and body weight at 24 h. It also caused an immediate drop in core body temperature, which was followed by an increase in body temperature. To understand these different effects of GALP on energy balance in mice compared to rats, and to determine the involvement of GALR2 and GALR3, immunohistochemistry was performed to localise c-Fos, a marker of cell activation. Intracerebroventricular injection of GALP induced c-Fos expression in the parenchyma surrounding the ventricles, the ventricular ependymal cells and the meninges in mice and rats. GALP also induced c-Fos expression in the supraoptic nucleus, dorsomedial hypothalamic nucleus, lateral hypothalamus and nucleus tractus solitarius in rats but not in mice. Central administration of a GALR2/3 agonist in rats did not induce c-Fos in any of the brain regions that expressed this protein after GALP injection, and had no effect on food intake, body weight and body temperature in rats or mice. These data suggest that GALP induces differential effects on energy balance and brain activity in mice compared to rats, which are unlikely to be due to activation of the GALR2 or GALR3 receptor.

Fullerene Nanomaterials Inhibit the Allergic Response

Fullerenes are a class of novel carbon allotropes that may have practical applications in biotechnology and medicine. Human mast cells (MC) and peripheral blood basophils are critical cells involved in the initiation and propagation of several inflammatory conditions, mainly type I hypersensitivity. We report an unanticipated role of fullerenes as a negative regulator of allergic mediator release that suppresses Ag-driven type I hypersensitivity. Human MC and peripheral blood basophils exhibited a significant inhibition of IgE dependent mediator release when preincubated with C(60) fullerenes. Protein microarray demonstrated that inhibition of mediator release involves profound reductions in the activation of signaling molecules involved in mediator release and oxidative stress. Follow-up studies demonstrated that the tyrosine phosphorylation of Syk was dramatically inhibited in Ag-challenged cells first incubated with fullerenes. In addition, fullerene preincubation significantly inhibited IgE-induced elevation in cytoplasmic reactive oxygen species levels. Furthermore, fullerenes prevented the in vivo release of histamine and drop in core body temperature in vivo using a MC-dependent model of anaphylaxis. These findings identify a new biological function for fullerenes and may represent a novel way to control MC-dependent diseases including asthma, inflammatory arthritis, heart disease, and multiple sclerosis.

Kidney transplantation procedures in rats: Assessments, complications, and management

Kidney transplantation in rats is an experimental model often used for the development of general microsurgical or transplantation techniques, for immunologic studies, and for analyzing transplant-associated long-term arterial blood-pressure changes. The aim of the present study was to analyze different surgical techniques of kidney transplantation in rats, with emphasis on minimizing surgical complications and establishing guidelines for their prevention and management. Complications were categorized into general (e.g., core body temperature drop, ischemic time) and surgically related vascular and urinary tract complications. In conclusion, a significant reduction of the complication rate in renal transplantation in rats can be achieved by placing the animal on a heating pad at an appropriate temperature. To reduce the risk of vascular thrombosis, ice-cold saline with heparin and careful flushing of the donor kidneys are recommended. Vascular complications can be avoided by performing "end-to-end" anastomosis techniques. The use of stents and cannulas in the urinary tract is associated with a high risk of urinary tract obstruction, and therefore is not recommended.

A New Method of Selective, Rapid Cooling of the Brain: An Experimental Study

To determine whether retrograde perfusion of cooled blood into one internal jugular vein (IJV) in the pig can selectively reduce the brain temperature without affecting the core body temperature (CBT). In 7 domestic pigs, the left IJV was catheterized on one side and a catheter placed with the tip immediately below the rete mirabile. Thermistors were placed in both brain hemispheres and the brain temperature continuously registered. Thermistors placed in the rectum registered the CBT. From a catheter in the right femoral vein blood was aspirated with the aid of a roller pump, passed through a cooling device, and infused into the catheter in the left IJV at an initial rate of 200 ml/min. Immediately after the start of the infusion of cooled blood (13.8 degrees C) into the IJV, the right brain temperature started to drop from its initial 37.9 degrees C and reached 32 degrees C within 5 min. By increasing the temperature of the perfusate a further drop in the brain temperature was avoided and the brain temperature could be kept around 32 degrees C during the experiment. In 4 of the animals a heating blanket was sufficient to compensate for the slight drop in CBT during the cooling period. We conclude that brain temperature can be reduced in the pig by retrograde perfusion of the internal jugular vein with cooled blood and that the core body temperature can be maintained with the aid of a heating blanket.

Gelures

Frostbite is a localised lesion caused by a direct freezing action on tissues. It is characterised by a gradual onset and a local numbness that may delay its medical management. The pathophysiology of frostbite is peripheral vasoconstriction secondary to a drop in core body temperature. The mainstay of primary medical treatment is a rapid re-warming, and the use of peripheral vasodilators. New management guidelines aim to reduce progression of frostbite to progressive secondary necrosis. A recent classification based on initial lesion involvement and bone scanning data defines four stages which correlate with long-term prognosis and have useful prognostic implications. At the stages III and IV, a risk of bony amputation is associated. Late surgical treatment aims to be maximally conservative and is discussed with plastic surgeons. But in case of uncontrolled sepsis emergency surgical treatment may be needed.

Guidelines for Prevention and Management of Complications Following Kidney Transplantation in Rats

Kidney transplantation in rats is a useful model for microsurgery, transplantation, and immunology studies. Our aim was to analyze various techniques of kidney transplantation in rats with emphasis on guidelines for the prevention and management of complications. Complications were categorized into general, vascular, and urological types and respectively attributed to long transplantation time, core body temperature drop, nonreplaced intraoperative blood loss, anastomosis failure, and ureteral anastomoses with stents or cannulas, which increase the risk of calculus formation. In conclusion, to decrease the complication rates the animal should be placed on a heating pad. For hemodynamic stability NaCl should be administered subcutaneously. To reduce the risk of thrombosis, ice-cold saline containing heparin should be administered. Vascular complications, which mainly depend on the microsurgeon’s expertise, can be prevented by meticulous surgical technique (preferably an end-in-end anastomosis). The main urinary complications can be minimized by avoiding stents and cannulas and focusing on using techniques like the bladder-patch technique.

Acute and phase-shifting effects of ocular and extraocular light in human circadian physiology.

Light can influence physiology and performance of humans in two distinct ways. It can acutely change the level of physiological and behavioral parameters, and it can induce a phase shift in the circadian oscillators underlying variations in these levels. Until recently, both effects were thought to require retinal light perception. This view was challenged by Campbell and Murphy, who showed significant phase shifts in core body temperature and melatonin using an extraocular stimulus. Their study employed popliteal skin illumination and exclusively considered phase-shifting effects. In this paper, the authors explore both acute effects and phase-shifting effects of ocular as well as extraocular light. Twelve healthy males participated in a within-subject design and received all of three light conditions--(1) dim ocular light/no light to the knee, (2) dim ocular light/bright extraocular light to the knee, and (3) bright ocular light/no light to the knee--on separate nights in random order. The protocol consisted of an adaptation night followed by a 26-h period of sustained wakefulness, during which a 4-h light pulse was presented at a time when maximal phase delays were expected. The authors found neither immediate nor phase-shifting effects of extraocular light exposure on melatonin, core body temperature (CBT), or sleepiness. Ocular bright-light exposure reduced the nocturnal circadian drop in CBT, suppressed melatonin, and reduced sleepiness significantly. In addition, the 4-h ocular light pulse delayed the CBT rhythm by -55 min compared to the drift of the CBT rhythm in dim light. The melatonin rhythm shifted by -113 min, which differed significantly from the drift in the melatonin rhythm in the dim-light condition (-26 min). The failure to find immediate or phase-shifting effects in response to extraocular light in a within-subjects design in which effects of ocular bright light are confirmed strengthens the doubts raised by other labs of the impact of extraocular light on the human circadian system.

Comparison of Traditional Thermal Support Devices With the Forced-Air Warmer System in Anesthetized Hispaniolan Amazon Parrots (Amazona ventralis)

Active warming of birds under general anesthesia is required to prevent hypothermia and its life-threatening consequences. The ability of a forced-air warming system to provide thermal homeostasis during isoflurane anesthesia of 10 Hispaniolan Amazon parrots (Amazona ventralis) was compared to a circulating-water blanket and an infrared heat emitter. Each bird was anesthetized once weekly for a 60-minute trial of each of 5 methods: no thermal support (control), surgical drape only, towel-covered circulating-water blanket and drape, infrared heat emitter and drape, and forced-air warmer and drape. An esophageal thermometer was used to measure the bird's core body temperature during each trial, and the temperature of the surgical area immediately adjacent to the bird as well as the ambient room temperature were also recorded. Time zero was 5 minutes after intubation. None of the warming methods prevented a significant decrease in core body temperature measured during the 60-minute trial period. A significant decrease in core body temperature was observed within 15 minutes with all warming methods except the forced-air warmer, which prevented a significant decrease in temperature before 30 minutes. Even though the forced-air warmer did not prevent a drop in core body temperature during the last 30 minutes of the trial, the temperature remained within the clinically acceptable range of 38.3–40.6°C. A significant increase occurred in the temperature of the surgical area immediately adjacent to each bird from 15 to 60 minutes for all warming methods, but the magnitude of the increase was not different among modalities. The forced-air warming system proved superior to traditional heating methods in restricting heat loss and is an effective modality for the prevention of hypothermia during isoflurane anesthesia of Hispaniolan Amazon parrots in clinical practice or a research setting.