Bench-to-bedside review: mechanisms and management of hyperthermia due to toxicity

Management of serotonin syndrome (toxicity)

Serotonin syndrome (toxicity), resulting from an excessive accumulation of serotonin in the central nervous system, it can occur due to various factors such as the initiation of medication, overdose or drug interactions. Diagnosing serotonin toxicity presents challenges as there are no definitive criteria. This review delves into the pathophysiology, incidence, clinical assessment and management of serotonin toxicity, stressing the significance of promptly recognizing and managing severe cases. Diagnosis relies primarily relies on clinical assessment due to the absence of specific laboratory tests. The Hunter Serotonin Toxicity criteria are commonly utilized but have only been validated in the overdose setting. Assessing the severity of toxicity is crucial for guiding management decisions. Supportive care, discontinuation of causative agents and symptomatic treatment are prioritized in management. Mild toxicity often requires withdrawal or reduction of the serotonergic agent, while more severe toxicity requires more aggressive resuscitative and supportive care. Severe serotonin toxicity characterized by hyperthermia and rigidity requires aggressive supportive measures, including benzodiazepines, intubation, paralysis and active cooling. Animal studies suggest potential benefits of 5-HT2A receptor antagonists in preventing hyperthermia and fatalities, but only at high doses. Their clinical effectiveness remains uncertain, and evidence is predominately from case series and case reports. Although commonly used, serotonin antagonists like cyproheptadine lack conclusive evidence of efficacy. Other serotonin antagonists such as chlorpromazine and olanzapine have been explored but evidence is limited to case reports. Hence, the cornerstone of treating severe cases does not lie in 'antidote' administration or even diagnosis but in effective early resuscitative and supportive care.

Perioperative Considerations for Patients Exposed to Psychostimulants

Concerns regarding the perioperative management of acute psychostimulant intoxication have been recognized for decades, but novel and diverse substances in this class continue to be developed. Despite the similarities in mechanisms of action among psychostimulants, each subclass within this broad category has unique receptor specificity and different mechanisms that play a role in patient clinical presentation. These issues present challenges to anesthesia providers when caring for patients with either acute or chronic exposure to psychostimulants during the perioperative period. Challenges result from both physiological and psychological effects that influence the action of the primary anesthetic agent, adjuvant anesthetics, and analgesics used for perioperative management of pain. The epidemiology, pharmacology, and perioperative implications of psychostimulant use are presented for amphetamines and similar acting nonamphetamines, cocaine, and, finally, the mixed-action drugs known as entactogens that share stimulant and psychedelic properties. This information is then used as the foundation for safe and effective perioperative management of patients exposed to psychostimulants.

Interstitial Photothermal Therapy Generates Durable Treatment Responses in Neuroblastoma

Photothermal therapy (PTT) represents a promising modality for tumor control typically using infrared light-responsive nanoparticles illuminated by a wavelength-matched external laser. However, due to the constraints of light penetration, PTT is generally restricted to superficially accessible tumors. With the goal of extending the benefits of PTT to all tumor settings, interstitial PTT (I-PTT) is evaluated by the photothermal activation of intratumorally administered Prussian blue nanoparticles with a laser fiber positioned interstitially within the tumor. This interstitial fiber, which is fitted with a terminal diffuser, distributes light within the tumor microenvironment from the "inside-out" as compared to from the "outside-in" traditionally observed during superficially administered PTT (S-PTT). I-PTT improves the heating efficiency and heat distribution within a target treatment area compared to S-PTT. Additionally, I-PTT generates increased cytotoxicity and thermal damage at equivalent thermal doses, and elicits immunogenic cell death at lower thermal doses in targeted neuroblastoma tumor cells compared to S-PTT. In vivo, I-PTT induces significantly higher long-term tumor regression, lower rates of tumor recurrence, and improved long-term survival in multiple syngeneic murine models of neuroblastoma. This study highlights the significantly enhanced therapeutic benefit of I-PTT compared to traditional S-PTT as a promising treatment modality for solid tumors.

R, Patel PH, Bazan DZ, Mora A, Samuel N, Mingle AC, Leon LR, Varon J, Surani S. Drug-Induced Hyperthermia Review

Humans maintain core body temperature via a complicated system of physiologic mechanisms that counteract heat/cold fluctuations from metabolism, exertion, and the environment. Overextension of these mechanisms or disruption of body temperature homeostasis leads to bodily dysfunction, culminating in a syndrome analogous to exertional heat stroke (EHS). The inability of this thermoregulatory process to maintain the body temperature is caused by either thermal stress or certain drugs. EHS is a syndrome characterized by hyperthermia and the activation of systemic inflammation. Several drug-induced hyperthermic syndromes may resemble EHS and share common mechanisms. The purpose of this article is to review the current literature and compare exertional heat stroke (EHS) to three of the most widely studied drug-induced hyperthermic syndromes: malignant hyperthermia (MH), neuroleptic malignant syndrome (NMS), and serotonin syndrome (SS). Drugs and drug classes that have been implicated in these conditions include amphetamines, diuretics, cocaine, antipsychotics, metoclopramide, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), and many more. Observations suggest that severe or fulminant cases of drug-induced hyperthermia may evolve into an inflammatory syndrome best described as heat stroke. Their underlying mechanisms, symptoms, and treatment approaches will be reviewed to assist in accurate diagnosis, which will impact the management of potentially life-threatening complications.

Allopurinol Lowers Serum Urate but Does Not Reduce Oxidative Stress in CKD

Xanthine oxidase (XO) contributes to oxidative stress and vascular disease. Hyperuricemia and gout are common in patients with chronic kidney disease (CKD), a population at increased risk of vascular disease. We evaluated effects of allopurinol on serum XO activity and metabolome of CKD patients who had participated in a randomized double-blind clinical trial of allopurinol vs. placebo. XO activity was measured in participants' serum. XO expression in venous endothelial cells was evaluated via immunofluorescence. Gas chromatography mass spectrometry (GC/MS) was utilized for metabolomics analysis. We found that in patients with stage 3 CKD and hyperuricemia, allopurinol lowered serum urate while increasing serum xanthine levels. Allopurinol, however, did not significantly suppress measured serum XO activity. Of note, baseline serum XO activity was low. Additionally, neither baseline serum XO activity nor XO protein expression were associated with measures of vascular dysfunction or with systemic or endothelial biomarkers of oxidative stress. Allopurinol affected several pathways, including pentose phosphate, pyrimidine, and tyrosine metabolism. Our findings suggest that circulating XO does not contribute to vascular disease in CKD patients. In addition to inhibition of XO activity, allopurinol was observed to impact other pathways; the implications of which require further study.

Differentiating probable nitrofurantoin-induced drug fever from antipsychotic-induced hyperthermia in a patient receiving clozapine

Nitrofurantoin (NIT) is a commonly utilized antibiotic for the treatment of UTIs. Although well tolerated, NIT is not without potential adverse reactions. This case report details the observation of probable NIT-induced drug fever in a patient receiving clozapine. A 61-year-old female with treatment-refractory schizoaffective disorder was admitted to a psychiatric unit with paranoia and auditory hallucinations, prompting clozapine initiation during day 1 of hospitalization. Due to worsening hallucinations and anxiety, antibiotic therapy with NIT for a presumed UTI was initiated 8 days after admission. Febrile episodes were observed beginning on hospital day (HD) 9, leading to concern for possible neuroleptic malignant syndrome (NMS), which led to clozapine discontinuation. The patient received a total of 3 doses of NIT with continued fever until discontinuation on HD 10. No further complications were encountered, and clozapine was safely resumed on HD 13. Although sparsely described in the medical literature, occurrences of drug fever attributable to NIT are previously reported. A review of the medical literature identified only 5 previously published articles specific to NIT-induced drug fever, none of which specified interruptions of psychotropic therapy for a patient with acute psychiatric decompensation. This case highlights the differential diagnosis of fever related to NIT in a patient receiving clozapine when NMS was initially suspected.

Potential Contribution of the Intestinal Microbiome to Phenethylamine-Induced Hyperthermia

Phenethylamines (e.g., methamphetamine) are a common source of drug toxicity. Phenethylamine-induced hyperthermia (PIH) can activate a cascade of events that may result in rhabdomyolysis, coagulopathy, and even death. Here, we review recent evidence that suggests a potential link between the gut-brain axis and PIH. Within the preoptic area of the hypothalamus, phenethylamines lead to changes in catecholamine levels, that activate the sympathetic nervous system (SNS) and increase the peripheral levels of norepinephrine (NE), resulting in: (1) the loss of heat dissipation through α1 adrenergic receptor (α1-AR)-mediated vasoconstriction, (2) heat generation through β-AR activation and subsequent free fatty acid (FFA) activation of uncoupling proteins (UCPs) in brown and white adipose tissue, and (3) alteration of the gut microbiome and its link to the gut-brain axis. Recent studies have shown that phenethylamine derivatives can influence the composition of the gut microbiome and thus its metabolic potential. Phenethylamines increase the relative level of Proteuswhich has been linked to enhanced NE turnover. Bidirectional fecal microbial transplants (FMT) between PIH-tolerant and PIH-naïve rats demonstrated that the transplantation of gut microbiome can confer phenotypic hyperthermic and tolerant responses to phenethylamines. These phenethylamine-mediated changes in the gut microbiome were also associated with epigenetic changes in the mediators of thermogenesis. Given the significant role that the microbiome has been shown to play in the maintenance of body temperature, we outline current studies demonstrating the effects of phenethylamines on the gut microbiome and how these microbiome changes may mechanistically contribute to alterations in body temperature.

Drugs of Abuse: Sympathomimetics

Sympathomimetic drugs comprise a broad category of substances including both illicit and prescribed drugs that have deleterious effects when ingested or abused. The clinical syndromes that result from overstimulation of the sympathetic nervous system by reuptake inhibition of biogenic amines, such as norepinephrine and dopamine, carry significant morbidity. Recognition and awareness of the appropriate supportive measures are required to mitigate life-threatening complications of multiple organ systems. The sympathomimetic toxidrome is recognized by a constellation of symptoms including agitation, hyperthermia, tachycardia, and hypertension, and the primary treatment involves supportive care, including the liberal use of benzodiazepines.

Toxicology of Psychoactive Substances

A trend in the increasing use of prescription psychoactive drugs (PADs), including antidepressants, antipsychotics, and mood stabilizers, has been reported in the United States and globally. In addition, there has been an increase in the production and usage of illicit PADs and emergence of new psychoactive substances (NPSs) all over the world. PADs pose unique challenges for critical care providers who may encounter toxicology issues due to drug interactions, side effects, or drug overdoses. This article provides a summary of the toxicologic features of commonly used and abused PADs: antidepressants, antipsychotics, mood stabilizers, hallucinogens, NPSs, caffeine, nicotine, and cannabis.

Combining ecstasy and ethanol: higher risk for toxicity? A review

Ecstasy use is commonly combined with ethanol consumption. While combination drug use in general is correlated with a higher risk for toxicity, the risk of the specific combination of ecstasy (3,4-methylenedioxymethamphetamine (MDMA)) and ethanol is largely unknown. Therefore, we have reviewed the literature on changes in MDMA pharmacokinetics and pharmacodynamics due to concurrent ethanol exposure in human, animal and in vitro studies. MDMA pharmacokinetics appear unaffected: the MDMA blood concentration after concurrent exposure to MDMA and ethanol was comparable to lone MDMA exposure in multiple human placebo-controlled studies. In contrast, MDMA pharmacodynamics were affected: locomotor activity increased and body temperature decreased after concurrent exposure to MDMA and ethanol compared to lone MDMA exposure. Importantly, these additional ethanol effects were consistently observed in multiple animal studies. Additional ethanol effects have also been reported on other pharmacodynamic aspects, but are inconclusive due to a low number of studies or due to inconsistent findings. These investigated pharmacodynamic aspects include monoamine brain concentrations, neurological (psychomotor function, memory, anxiety, reinforcing properties), cardiovascular, liver and endocrine effects. Although only a single or a few studies were available investigating these aspects, most studies indicated an aggravation of MDMA-induced effects upon concurrent ethanol exposure. In summary, concurrent ethanol exposure appears to increase the risk for MDMA toxicity. Increased toxicity is due to an aggravation of MDMA pharmacodynamics, while MDMA pharmacokinetics is largely unaffected. Although a significant attenuation of the MDMA-induced increase of body temperature was observed in animal studies, its relevance for human exposure remains unclear.

Drug-associated hyperthermia: A longitudinal analysis of hospital presentations

WHAT IS KNOWN AND OBJECTIVE

Hyperthermia occurs when heat accumulation surpasses the body's ability for heat dissipation. Many drugs can affect thermoregulation through mechanisms including altering the neurotransmitters that cause increased heat production or decreased heat loss and may, therefore, be associated with hyperthermia. This study aimed to examine hospitalizations and emergency department (ED) presentations due to hyperthermia and to investigate the potential association with drug therapy.

METHODS

A retrospective analysis of ED presentations and hospitalizations due to hyperthermia in all four major hospitals in Tasmania, Australia, between July 2010 and December 2018 was performed. Data of patients aged ≥18 years were extracted from the hospital digital medical records and analysed for the prevalence, trends and various potential risk factors for hyperthermia, such as age, environmental temperature and drug therapy.

RESULTS

This study included 224 patients. The data illustrated a trend with time, albeit not statistically significant, towards increasing hospital presentations due to hyperthermia. Antiepileptics (P = .03) and furosemide (P = .04) were the most frequently used drugs in patients with primary hyperthermia. The high use of levothyroxine in the study population (6.7%) stood out compared with the estimated national average (2.1%). Various drug classes associated with hyperthermia were used significantly more in the age group ≥60 years, suggesting polypharmacy in the elderly as a contributing factor for hyperthermia.

WHAT IS NEW AND CONCLUSION

This study reports a possible association of some drugs, particularly diuretics (furosemide), antiepileptics and levothyroxine, with hyperthermia. Healthcare professionals should be aware of the increasing prevalence of hyperthermia and the possible involvement of drugs.

The hot patient: acute drug-induced hyperthermia

Drugs can cause dysregulation of the hypothalamic–pituitary–adrenal axis which can result in a rise in core temperature This type of hyperthermia is unresponsive to antipyretics and can be complicated by rhabdomyolysis multi-organ failure and disseminated intravascular coagulation

Organic causes of fever such as infection must be ruled out Syndromes associated with drug-induced fever include neuroleptic malignant syndrome and anticholinergic sympathomimetic and serotonin toxicity

The class of offending drugs as well as the temporal relationship to starting or stopping them assists in differentiating between neuroleptic malignant syndrome and serotonin toxicity

Immediate inpatient management is needed The mainstay of management is stopping the drug and supportive care often in the intensive care unit

[Fever in the critically ill : To treat or not to treat]

Fever, arbitrarily defined as a core body temperature >38.3 °C, is present in 20-70 % of intensive care unit patients. Fever caused by infections is a physiologic reset of the thermostatic set-point and is associated with beneficial consequences, but may have negative sequelae with temperatures >39.5 °C. Fever of non-infectious and neurologic origin affects about 50 % of patients with elevated body temperature, presents as a pathologic loss of thermoregulation, and may be associated with untoward side effects at temperatures above 38.5-39.0 °C. Cooling can be achieved by physical and pharmacologic means. Evidence-based recommendations are not available. The indication for a cooling therapy can only be based on the physiologic reserve and the neurologic, hemodynamic, and respiratory state. The temperature should be lowered to the normothermic range. Hyperthermia syndromes require immediate physical cooling (and dantrolen when indicated).

Neuroleptic Malignant Syndrome Secondary to Metoclopramide Use in an Elderly Gastroenterologic Surgery Patient

An 84-year-old African American woman was admitted to the hospital secondary to severe abdominal pain accompanied by septic shock. She underwent exploratory laparotomy, which revealed extensive small bowel necrosis likely due to small bowel torsion. A small bowel resection was performed with primary anastomoses and the patient was subsequently transferred to the intensive care unit (ICU). She recovered from shock but had a persistent gastroparesis interfering with enteral feeding, for which metoclopramide was prescribed. She was then transferred to a general medical-surgical unit in a stable condition where she received a total of four 10-mg oral doses of metoclopramide administered every 8 hours. Approximately 32 hours after receiving the first dose of metoclopramide, the patient was subsequently transferred back to the ICU because of fever and inability to maintain respirations. Neuroleptic malignant syndrome was suspected, and the patient was intubated and received supportive care. After a week in the ICU, she was discharged back to the medical-surgical unit in a stable condition and recovered completely. The patient was later discharged home.

Dexmedetomidine-Associated Hyperthermia: A Retrospective Cohort Study of Intensive Care Unit Admissions between 2009 and 2016

Dexmedetomidine-associated hyperthermia has not been previously studied. Analysis is warranted to determine whether this potentially dangerous complication is more prevalent than previously realised. We aimed to examine the association between dexmedetomidine and temperature ≥39.5°C, including patient characteristics, temporality and potential risk factors. We conducted a retrospective cohort study of all intensive care unit (ICU) admissions between 1 July 2009 and 31 May 2016 in a tertiary ICU in Australia. Temperature data was available for 9,782 ICU admissions. Dexmedetomidine was given intravenously to 611 (6.3%) patients at a dose of 0 to 1.5 g/kg/hour. Temperatures ≥39.5°C were recorded in 341 (3.5%) patients. Overall hospital mortality was 10.8% for all admissions and 29.3% for patients with temperatures ≥39.5°C. Dexmedetomidine exposure was more frequent in patients with temperature recordings ≥39.5°C compared to those with temperatures <39.5°C, 11.94% versus 2.94% (odds ratio [OR] 4.49; 95% confidence intervals [CI] 3.37, 5.92; P <0.001). The association was stronger for patients post-open heart surgery (OHS) with temperatures ≥39.5°C (OR 12.9; 95% CI 5.01, 31.62; P <0.001). Multivariate analysis showed an independent association between dexmedetomidine and a temperature ≥39.5°C in two particular patient groups: OHS (OR 2.72; 95% CI 1.1, 6.9; P <0.001), and obesity (OR 3.44; 95% CI 1.5, 7.9; P <0.001). Dexmedetomidine exposure is associated with an increased risk of hyperthermia. Possible risk factors are open heart surgery and obesity.

Survey on Hypothermia and Hyperthermia in Poisoned Patients in a Unique Referral Hospital, Tehran, Iran

Background

Body temperature is a critical criterion of health. Drugs and a variety of poisons can affect body temperature in poisoned patients, causing hyperthermia and hyperpyrexia.

Objectives

Our previous study’s findings in patients poisoned with organophosphate led us to the goal of this study: obtaining the initial tympanic temperature in patients poisoned by a variety of toxins.

Materials and Methods

A cross-sectional study reviewed the records of poisoned patients who were admitted to the toxicological intensive care unit (TICU) at Loghman Hakim hospital poison center (LHHPC) from February 2014 to February 2015. The data collected included gender, age, type of poisoning, the season during which poisoning occurred, vital signs, initial tympanic temperature (first four hours), presence of seizures, white blood cell (WBC) count, creatinine phosphokinase (CPK), length of stay and patient outcome. We determined the mean (SD) for normally distributed continuous variables, the median and interquartile range for non-normally distributed continuous variables, and the absolute and relative frequency (%) for categorical variables. All were determined using SPSS version 16.

Results

Data were collected from 310 eligible patients. The mean patient age was 32.65 (with a standard deviation of 14.40). Of the patients in the study, 183 (59%) were male. Intentional poisoning in an attempted suicide was documented in 253 (81.6%) patients. The most prevalent poisoning agent was aluminum phosphate (18.70%), followed by methadone (10%) and opium (10%). Seventy percent of the patients (n = 217) were diagnosed and classified with fever or hyperthermia. A temperature ≥ 40°C was detected in just three cases. The highest mean temperature was found in patients poisoned with amphetamine, organophosphate and tramadol. Patients with alcohol and phenobarbital poisoning were included in the sample, but these patients were not diagnosed with hypothermia. WBC ≥ 10,000 cells/mL and CPK ≥ 975 IU/L were recorded in 57.7% and 13.2% of subjects, respectively.

Conclusions

Body temperature changes in human poisonings are a matter in need of special attention. A literature review did not reveal any controversy over hypothermia, but poisoning cases exhibit a variety of patterns of fever and hyperthermia. If there are no limits to the diagnosis of fever and hyperthermia, all cases with a poor prognosis which fail to respond to treatment could be categorized as drug-induced hyperthermia. Therefore, a different approach is needed for poisoning cases.

Climate change: challenges and opportunities for global health

IMPORTANCE

Health is inextricably linked to climate change. It is important for clinicians to understand this relationship in order to discuss associated health risks with their patients and to inform public policy.

OBJECTIVES

To provide new US-based temperature projections from downscaled climate modeling and to review recent studies on health risks related to climate change and the cobenefits of efforts to mitigate greenhouse gas emissions.

DATA SOURCES, STUDY SELECTION, AND DATA SYNTHESIS

We searched PubMed and Google Scholar from 2009 to 2014 for articles related to climate change and health, focused on governmental reports, predictive models, and empirical epidemiological studies. Of the more than 250 abstracts reviewed, 56 articles were selected. In addition, we analyzed climate data averaged over 13 climate models and based future projections on downscaled probability distributions of the daily maximum temperature for 2046-2065. We also compared maximum daily 8-hour average ozone with air temperature data taken from the National Oceanic and Atmospheric Administration, National Climate Data Center.

RESULTS

By 2050, many US cities may experience more frequent extreme heat days. For example, New York and Milwaukee may have 3 times their current average number of days hotter than 32°C (90°F). High temperatures are also strongly associated with ozone exceedance days, for example, in Chicago, Illinois. The adverse health aspects related to climate change may include heat-related disorders, such as heat stress and economic consequences of reduced work capacity; respiratory disorders, including those exacerbated by air pollution and aeroallergens, such as asthma; infectious diseases, including vectorborne diseases and waterborne diseases, such as childhood gastrointestinal diseases; food insecurity, including reduced crop yields and an increase in plant diseases; and mental health disorders, such as posttraumatic stress disorder and depression, that are associated with natural disasters. Substantial health and economic cobenefits could be associated with reductions in fossil fuel combustion. For example, greenhouse gas emission policies may yield net economic benefit, with health benefits from air quality improvements potentially offsetting the cost of US and international carbon policies.

CONCLUSIONS AND RELEVANCE

Evidence over the past 20 years indicates that climate change can be associated with adverse health outcomes. Health care professionals have an important role in understanding and communicating the related potential health concerns and the cobenefits from policies to reduce greenhouse gas emissions.

Methamphetamine-induced toxicity: an updated review on issues related to hyperthermia

Reports of methamphetamine-related emergency room visits suggest that elevated body temperature is a universal presenting symptom, with lethal overdoses generally associated with extreme hyperthermia. This review summarizes the available information on methamphetamine toxicity as it pertains to elevations in body temperature. First, a brief overview of thermoregulatory mechanisms is presented. Next, central and peripheral targets that have been considered for potential involvement in methamphetamine hyperthermia are discussed. Finally, future areas of investigation are proposed, as further studies are needed to provide greater insight into the mechanisms that mediate the alterations in body temperature elicited by methamphetamine.

Diagnosis and treatment of drug-induced hyperthermia

PURPOSE

The etiology, pathophysiology, clinical presentation, and management of drug-induced hyperthermia (DIH) syndromes are reviewed.

SUMMARY

DIH syndromes are a rare and often overlooked cause of body temperature elevation and can be fatal if not recognized promptly and managed appropriately. There are five major DIH syndromes: (1) neuroleptic malignant syndrome, (2) serotonin syndrome, (3) anticholinergic poisoning, (4) sympathomimetic poisoning, and (5) malignant hyperthermia. The differential diagnosis of DIH syndromes can be challenging because symptoms are generally nonspecific, ranging from blood pressure changes and excessive sweating to altered mental status, muscle rigidity, convulsions, and metabolic acidosis. Evidence from the professional literature (per a MEDLINE search for articles published through November 2011) indicates that few currently available treatment options can reduce the duration of hyperthermia; therefore, prompt identification of the provoking agent based on the patient's medication history, the clinical presentation, and the timing of symptom onset is essential to determine the appropriate treatment and mitigate potentially life-threatening sequelae. For all DIH syndromes, appropriate management includes the immediate discontinuation of the suspected offending agent(s) and supportive care (external cooling, volume resuscitation as needed); in some cases, pharmacologic therapy (e.g., a benzodiazepine, bromocriptine, dantrolene) may be appropriate, with the selection of a specific agent primarily determined by the medication history and suspected DIH syndrome.

CONCLUSION

DIH is a hypermetabolic state caused by medications and other agents that alter neurotransmitter levels. The treatment of DIH syndromes includes supportive care and pharmacotherapy as appropriate.

Bath salts: a newly recognized cause of acute kidney injury

Bath salts are substance of abuse that are becoming more common and are difficult to recognize due to negative toxicology screening. Acute kidney injury due to bath salt use has not previously been described. We present the case of a previously healthy male who developed acute kidney injury and dialysis dependence after bath salt ingestion and insufflation. This was self-reported with negative toxicology screening. Clinical course was marked by severe hyperthermia, hyperkalemia, rhabdomyolysis, disseminated intravascular coagulation, oliguria, and sepsis. We discuss signs and symptoms, differential diagnoses, potential mechanisms of injury, management, and review of the literature related to bath salt toxicity.

Hyperthermia-induced micronucleus formation in a human keratinocyte cell line

Elevated temperature can cause biological effects in vitro and in vivo. Many studies on effects of hypo- and hyperthermia have been conducted, but only few studies systematically investigated the formation of genomic damage in the micronucleus test in human cells in vitro as a consequence of different temperatures. In the present study, HaCaT human keratinocytes were exposed to different temperatures from 37°C to 42°C for 24h in a regular cell culture incubator. Micronucleus frequency as a marker of genomic damage was elevated in a temperature-dependent and statistically significant manner. Apoptosis occurred at temperatures of 39°C or higher. Cell proliferation was unaffected up to 40°C and decreased at 41°C and 42°C. Expression of the heat shock protein Hsp70 was elevated, particularly at temperatures of 40°C and higher. These findings are in agreement with several in vivo studies and some in vitro studies looking at single, specific temperatures, but a systematically investigated temperature-dependent increase of genomic damage in human keratinocytes in vitro is demonstrated for the first time here.

[Vulnerability to environmental heat among persons with mental health problems]

This review is intended to alert health professionals to the particular vulnerability of persons with mental health problems or taking certain medications to heat-related illness, a threat that is increasing due to climate change. It reviews epidemiology, physiology and clinical features of heat-related illness. For acute medical management, it refers readers to existing guidelines and recommendations. It reviews risk and protective factors. Finally, it presents preventive strategies that may help reduce the impact of heat-related illness in this population.

Management of the hyperthermic patient

Undifferentiated body temperature of greater than 38°C can herald a number of important clinical syndromes essential to diagnose besides just infectious aetiologies. This review examines the pathophysiology, clinical features and approach to the management of hyperthermia that will lead to appropriate diagnosis and treatment.

Heatwaves and their impact on people with alcohol, drug and mental health conditions: a discussion paper on clinical practice considerations

AIM

This article discusses the clinical implications of adverse health outcomes derived during heatwaves for people with mental health disorders, substance misuse and those taking prescribed medications such as lithium, various neuroleptic and anticholinergic drugs.

BACKGROUND

With climate change it is predicted that the incidence of prolonged periods of extreme heat will increase. Specific adverse health outcomes associated with high environmental temperatures include heat stroke and heat exhaustion. Those at increased risk for heat-related mortality are those with chronic health conditions, including those with mental health disorders and substance misuse.

DATA SOURCES

Sources of evidence included and 'grey' literature published between 1985 and 2010, such as key texts, empirical research, public policies, training manuals and community information sheets on heat waves.

DISCUSSION

Current clinical practice and clinical impact of heatwaves on those people with comorbidity is explored. This includes the physiological components of heat stress, heat regulation, and the impact of alcohol and other drugs; and, ramifications and professional practice issues for those with mental health conditions and those requiring mental health medications.

IMPLICATIONS FOR NURSING

Client education covering modification of the environment and the use of client heat safety action plans. Secure, accessible stores of prescribed medication are recommended and emergency substance withdrawal kits could be made available.

CONCLUSION

All nurses have a responsibility to increase the capability and resilience of their clients to manage their chronic health needs during a heatwave. At these times nurses need to give extra monitoring and assistance when clients lack the capacity or resources to protect themselves.

Differential effect of hyperthermia on nerves and smooth muscle of the mouse ileum

BACKGROUND AND OBJECTIVES

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) gained wide acceptance as the treatment of choice for selected patients with peritoneal surface malignancies. Patients tend to suffer from prolonged ileus following CRS + HIPEC, complicating their recovery. We studied the effects of hyperthermia on the intestine to gain insight into mechanisms of ileus post-HIPEC.

METHODS

Segments of mouse ileum were incubated at 36°C. Electrical field stimulation (EFS) was applied, stimulating nerves, and the resultant muscle contraction was measured. The response was measured at varying temperatures (38-43°C) at exposure times of up to 120 min. We also stimulated the tissues with 10(-6) M carbachol, a muscarinic receptor agonist, which acts directly on smooth muscle.

RESULTS

Response to EFS decreased at high temperatures, especially above 41°C. This effect was irreversible for 120 min after decreasing temperature. When stimulating with carbachol, both transient and plateau responses decreased at 43°C (plateau more than transient) but the effect reversed on returning to 36°C.

CONCLUSION

The irreversible decline in responses to nerve stimulation when exposed to high temperatures was not seen with direct muscle stimulation. This indicates that smooth muscle is resilient and that the main effect of hyperthermia is on nerves. These results have significance for HIPEC.

Adverse drug reactions resulting in hyperthermia in the intensive care unit

Hyperthermia is frequently seen in the intensive care setting and is associated with significant morbidity and mortality. It is often initially misdiagnosed as fever associated with infection. Atypical presentations of classic syndromes are common. Clinical suspicion is the key to diagnosis. Adverse drug reactions are a frequent culprit. Syndromes include adrenergic "fever," anticholinergic "fever," antidopaminergic "fever," serotonin syndrome, malignant hyperthermia, uncoupling of oxidative phosphorylation, and withdrawal from baclofen. This review describes the pathophysiology of hyperthermia, as distinct from fever, and the physiology, diagnosis, and treatment of serotonin syndrome, neuroleptic malignant syndrome, malignant hyperthermia, and baclofen withdrawal. Much of the available evidence regarding the treatment of these disorders is based on single case reports, case series, or animal models. Therapeutic modalities consist of identification/withdrawal of possible offending agent(s), support directed at lowering temperature and preventing/treating complications, as well as targeted pharmacologic therapy directed at the specific cause. Early recognition and treatment using a multidisciplinary approach are essential to achieve the best possible outcome.