Perioperative temperature elevation: not all hyperthermia is malignant hyperthermia

Intraoperative tourniquet-induced hyperthermia in a pediatric patient: a forgotten association -a case report

BACKGROUND

The intraoperative use of tourniquets is associated with several complications, including hyperthermia. We present the first documented case of tourniquet-induced hyperthermia in a pediatric patient at our institution.

CASE

A 5-year-old female with no past medical history underwent tendon release surgery for congenital talipes equinovarus under general anesthesia. Following inflation of a pneumatic tourniquet to a pressure of 250 mmHg on her left thigh, the patient experienced a gradual increase in body temperature. Despite the implementation of cooling measures, the temperature continued to increase until it plateaued. The hyperthermia gradually resolved upon deflation of the tourniquet.

CONCLUSIONS

Tourniquet-induced hyperthermia should be considered as a potential cause of intraoperative hyperthermia, particularly in the absence of typical signs of malignant hyperthermia. Early recognition and appropriate management, including deflation of the tourniquet and implementation of cooling measures, are crucial for preventing potential complications associated with hyperthermia.

Accuracy of a Dual-Sensor Heat-Flux (DHF) Non-Invasive Core Temperature Sensor in Pediatric Patients Undergoing Surgery

Accurate temperature measurement is crucial for the perioperative management of pediatric patients, and non-invasive thermometry is necessary when invasive methods are infeasible. A prospective observational study was conducted on 57 patients undergoing elective surgery. Temperatures were measured using a dual-sensor heat-flux (DHF) thermometer (Tcore™) and a rectal temperature probe (TRec), and the agreement between the two measurements was assessed. The DHF measurements showed a bias of +0.413 °C compared with those of the TRec. The limits of agreement were broader than the pre-defined ±0.5 °C range (-0.741 °C and +1.567 °C). Although the DHF sensors tended to overestimate the core temperature compared to the rectal measurements, an error grid analysis demonstrated that 95.81% of the DHF measurements would not have led to a wrong clinical decision, e.g., warming or cooling when not necessary. In conclusion, the low number of measurements that would have led to incorrect decisions suggests that the DHF sensor can be considered an option for continuous temperature measurement when more invasive methods are infeasible.

Temperature Monitoring and Thermal Support in Exotic Animal Critical Care

Body temperature measurement is one of the most important parameters to assess the health of a patient. In small exotic mammals, rectal temperature is obtained via a similar process as in dogs or cats, with a few specific differences. In reptiles and birds, measurement of body temperature can provide important information, albeit its accuracy may be limited. In most animals, temperature should be taken at the beginning of the examination to not artificially elevate the temperature during the physical exam. Heat support is typically indicated any time a patient's temperature is below the accepted core temperature range and cooling may be indicated whenever a patient's temperature exceeds a critical point.

Modeling iatrogenic intraoperative hyperthermia from external warming in children: A pooled analysis from two prospective observational studies

BACKGROUND

Maintenance of normothermia is an important quality metric in pediatric anesthesia. While inadvertent hypothermia is effectively prevented by forced-air warming, this therapeutic approach can lead to iatrogenic hyperthermia in young children.

AIMS

To estimate the influence of external warming by forced air on the development of intraoperative hyperthermia in anesthetized children aged 6 years or younger.

METHODS

We pooled data from two previous clinical studies. Primary outcome was the course of core temperature over time analyzed by a quadratic regression model. Secondary outcomes were the incidence of hyperthermia (body core temperature >38°C), the probability of hyperthermia over the duration of warming in relation to age and surface-area-to-weight ratio, respectively, analyzed by multiple logistic regression models. The influence of baseline temperature on hyperthermia was estimated using a Cox proportional hazards model.

RESULTS

Two hundred children (55 female) with a median age of 2.1 [1^st -3^rd quartile 1-4.2] years were analyzed. Mean temperature increased by 0.43°C after 1 h, 0.64°C after 2 h, and reached a peak of 0.66°C at 147 min. Overall, 33 children were hyperthermic at at least one measurement point. The odds ratios of hyperthermia were 1.14 (95%-CI: 1.07-1.22) or 1.13 (95%-CI: 1.06-1.21) for every 10 min of warming therapy in a model with age or surface-area-to weight ratio (ceteris paribus), respectively. Odds ratio was 1.33 (95%-CI: 1.07-1.71) for a decrease of 1 year in age and 1.63 (95%-CI: 0.93-2.83) for an increase of 0.01 in the surface-to-weight-area ratio (ceteris paribus). An increase of 0.1°C in baseline temperature increased the hazard of becoming hyperthermic by a factor of 1.33 (95%-CI: 1.23-1.43).

CONCLUSIONS

In children, external warming by forced-air needs to be closely monitored and adjusted in a timely manner to avoid iatrogenic hyperthermia especially during long procedures, in young age, higher surface-area-to-weight ratio, and higher baseline temperature.

Complications From Operator Modification of the Esophageal Temperature Probe

Intraoperative temperature monitoring of surgical patients is an important aspect of perioperative care. Central core temperature monitoring is often accomplished using an 18 French esophageal device inserted through the mouth into the esophagus, while patients are undergoing general anesthesia. Placement of a modified esophageal temperature probe (i.e. with the protective plastic covering removed) into the nasopharynx of a patient may cause significant patient harm by injuring the nasal mucosa and/or turbinates. An internal survey of current practice at our academic institution reveals that 78% of anesthesia providers modify the esophageal temperature probes, leading to an 11% injury incidence. A practical solution to avoid complications is to place a pediatric size 9 French esophageal temperature probe into the nasopharynx to monitor the central core temperature.

A Rare Case of Drug Interaction Presenting as Perioperative Hyperthermia in a Patient Presenting for Neurosurgery

Perioperative hyperthermia has many differential diagnoses. This case report describes the rare causation of perioperative hyperthermia in a patient presenting for epilepsy surgery. The patient had two episodes of hyperthermia, initially post-anesthetic induction and later in the immediate post-operative period. The quest for the etiology sheds light on a rare drug interaction between topiramate, an antiepileptic drug, and glycopyrrolate causing intraoperative hyperthermia. However, the literature has not reported drug interaction between topiramate and glycopyrrolate resulting in perioperative hyperthermia. The combination of a glycopyrrolate-induced rise in temperature and oligohidrosis could have resulted in hyperthermia in our patient. Thus, it is prudent to avoid glycopyrrolate in the perioperative period when patients are on topiramate.

The Accuracy of a Wireless Axillary Thermometer for Core Temperature Monitoring in Pediatric Patients Having Noncardiac Surgery: An Observational Study

PURPOSE

A wireless and wearable axillary thermometer (iThermonitor) has been validated for perioperative core temperature monitoring in adults. The purpose of this study was to evaluate its accuracy in pediatrics having non-cardiac surgery.

DESIGN

Prospective observational study.

METHODS

From January 2019 to December 2019, 70 children aged younger than 14 years undergoing surgery in a tertiary hospital were selected. Pairs of esophageal temperatures (T_Eso), rectal temperatures (T_Rec), and axillary temperatures monitored by the iThermonitor (T_iTh) were collected every 5 min during surgery. Taking T_Eso as reference, the bias between T_Eso and T_iTh and the proportion of bias within ±0.5°C were calculated. Bland-Altman method was used to analyze the 95% of limits of agreement (LOA) between T_iTh and T_Eso. The same analyses were done for T_Rec. FINDINGS: A total of 2232 pairs of temperatures were collected. The bias (mean ± SD) between T_iTh and T_Eso was -0.07 °C ± 0.25°C, and 95% LOA was -0.07°C ± 0.50°C. The proportion of bias within ±0.5°C accounted for 96% (95% Confidence Interval [CI], 92-98%). Higher bias and 95% LOA, and lower proportion of bias within ± 0.5°C were found between T_Rec and T_Eso than those between T_iTh and T_Eso.

CONCLUSION

During pediatric non-cardiac surgery, axillary temperature derived from iThermonitor is in good agreement with esophageal temperature and can be used as an alternative to core temperature.

Protective effect of dihydromyricetin on hyperthermia-induced apoptosis in human myelomonocytic lymphoma cells

Dihydromyricetin (DMY) is a traditional herbal medicine, with a wide range of biological activities. Extreme hyperthermia (HT) can suppress the immune system; thus, protection of the immune system is beneficial in heat-related diseases, including heatstroke. In our study, we revealed the protective effect of DMY against HT-induced apoptosis and analysed the underlying molecular mechanisms. We incubated human myelomonocytic lymphoma U937 cells at 44 °C for 30 min with or without DMY and followed by further incubation for 6 h at 37 °C. Cell viability was determined by the CCK-8 assay. DMY did not cause any cytotoxic effects in U937 cells even at high doses. HT treatment alone induced significant apoptosis, which was detected by DNA fragmentation and Annexin V/PI double staining. Mitochondrial dysfunction was identified by loss of mitochondrial membrane potential (MMP) during heat stimulation. Apoptotic related proteins were involved, truncated Bid and caspase-3 were upregulated, and Mcl-1 and XIAP were downregulated. We also identified the related signalling pathways, such as the MAPK and PI3K/AKT pathways. However, changes in HT were dramatically reversed when the cells were pretreated with DMY before exposure to HT. Overall, MAPKs and PI3K/AKT signalling, mitochondrial dysfunction, and caspase-mediated pathways were involved in the protective effect of DMY against HT-induced apoptosis in U937 cells, which was totally reversed by DMY pretreatment. These findings indicate a new clinical therapeutic strategy for the protection of immune cells during heatstroke.

A comprehensive review of malignant hyperthermia: Preventing further fatalities in orthopedic surgery

Most frequently associated with orthopedic surgery, malignant hyperthermia is a rare genetic condition linked to volatile anesthetics and succinylcholine. If not treated quickly with appropriate measures, death may result. To aid in the prevention of further fatalities, this review seeks to educate clinicians and staff on the presentation and treatment of this disease, as well as to provide a comprehensive overview by further addressing prevalence, similar conditions, pathogenesis and other aspects. Although the number of deaths due to malignant hyperthermia has greatly declined in the last several years, increased knowledge may eliminate associated mortalities, particularly in the orthopedic setting.

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.

Using a Vulnerability Theoretical Model to Assess the Malignant Hyperthermia Susceptible Population: Implications for Advanced Practice Emergency Nurses

Malignant hyperthermia (MH) is a high-risk, low-occurrence medical emergency with symptoms that include a severe increased rate of metabolic activity and rigid skeletal muscles. Clinicians should be knowledgeable and prepared for an MH event because it can occur in areas outside the operating room and without anesthetic triggers. Patients who have this rare genetic condition may come to the emergency department (ED) presenting with symptoms of heat stroke. However, the incidence of suspected MH in the ED or other critical care areas is not easily quantifiable because clinicians may not report cases to a centralized registry. The purpose of this article is to describe the MH-susceptible vulnerable population, to apply a vulnerability theoretical model to assess patients and families, to identify strategies for health promotion to reduce vulnerability, and to discuss how advanced practice nurses who specialize in emergency care can help decrease the vulnerability of MH-susceptible patients and families. By using a vulnerability model to assess the MH-susceptible population, nurses can effectively sort out strategies to prevent poor patient outcomes related to MH and promote health for this high-risk population. Measuring accurate core temperatures, applying effective cooling methods, and administering dantrolene are key concepts in caring for a patient who is experiencing an MH event. Advanced practice emergency nurses can participate in reducing vulnerability for this population by applying the Emergency Nurses Association Clinical Nurse Specialist competencies to MH-related vulnerabilities. Enhancing preparedness, evaluating and coordinating education programs, advocating for report submissions to the North American Malignant Hyperthermia Registry, and assessing opportunities for community collaboration are among the strategies discussed for reducing vulnerability for the MH-susceptible population.