Therapeutic Hypothermia and Temperature Management

Although evidence-based recommendations for preventing perioperative unintentional hypothermia have long been available, observational studies evaluating their implementation in hospital practice and the effectiveness of preventive interventions in at-risk patients are limited. This study aimed to determine the scope of nursing interventions for preventing perioperative unintentional hypothermia and examine the relationship between patient characteristics and these practices. This study employed a descriptive observational design. Patients undergoing elective surgery in the surgical units (orthopedics, gynecology, urology, neurosurgery, general surgery, and cardiovascular surgery) of a tertiary hospital in Turkey were observed preoperatively, intraoperatively, and on the first postoperative day. The mean age of the participants was 51.30 ± 19.32 years; 77% were overweight or obese, 55.2% had chronic diseases, and 39.6% underwent surgeries lasting more than 2 hours. The findings indicated that the duration of surgery was a significant determinant of nurses’ perioperative hypothermia prevention practices. In longer procedures, nurses’ awareness of hypothermia risk increased, which was reflected in patient education, environmental temperature management, and the use of active and passive warming methods (p < 0.05). This study highlights the importance of educational programs, strengthening standard care protocols, and policy development to enhance nurses’ awareness and practice in preventing perioperative unintentional hypothermia. In conclusion, effective strategies are needed to improve nursing practice and promote evidence-based interventions in this area.

Hypoxic–ischemic encephalopathy (HIE) is a critical neonatal condition for which therapeutic hypothermia (TH) remains the cornerstone of neuroprotective intervention. Clinical observations and prior studies note that electrolyte imbalances—particularly hyponatremia and hypokalemia—frequently emerge during TH. Therefore, this study explores how activation of the renin–angiotensin–aldosterone system (RAAS) may contribute to sodium (Na) and potassium (K) disturbances in asphyxiated neonates receiving TH. In this prospective study, 38 newborns with HIE treated with TH and 21 healthy term newborns were enrolled. Serum renin, aldosterone, Na, K, and urinary electrolyte levels were measured at 24, 48, and 72 hours postnatally. Receiver operating characteristic analyses assessed the diagnostic performance of renin and aldosterone. Renin and aldosterone levels were significantly elevated in the TH group compared with controls (p < 0.05). Serum sodium levels were consistently lower at all time points (p = 0.001), while potassium levels were significantly reduced at 24 and 72 hours (p < 0.05). Fractional excretion of sodium was increased at 24 hours, and potassium excretion remained elevated throughout the TH period (p < 0.05). Among the biomarkers, aldosterone demonstrated excellent diagnostic performance at 24 hours (AUC = 0.919). Activation of the RAAS is evident in asphyxiated neonates undergoing TH, with aldosterone playing a pivotal role in electrolyte disturbances. These results highlight the clinical importance of vigilant monitoring and timely correction of serum sodium and potassium levels during the hypothermia protocol.

Therapeutic hypothermia is widely used as a neuroprotective intervention in infants with hypoxic-ischemic encephalopathy (HIE); however, limited data exist regarding the long-term neurodevelopmental outcomes of different cooling strategies. The aim of this study is to compare the long-term neurodevelopmental and cognitive outcomes of combined hypothermia (CH) and whole-body cooling (WBC) treatments in children diagnosed with HIE with each other and with a healthy control group without an HIE diagnosis. This retrospective study included a total of 50 children diagnosed with HIE and treated with cooling therapy, who were followed in the Neonatal Intensive Care Unit of Mersin University between 2015 and 2021. Additionally, a control group was formed from healthy children of a similar age group who attended outpatient clinic checkups between these dates and whose archive records were accessible. We used the Wechsler Intelligence Scale for Children-IV (WISC-IV), the Stroop Test, and the Denver II Developmental Screening Test for neurodevelopmental assessments. Neurodevelopmental outcomes were generally found to be similar between the two groups. However, the Full Scale IQ of the CH group was found to be significantly lower compared to the control group. The groups that underwent cooling treatment showed more abnormalities in the Stroop and Denver tests compared to the control group. Although no significant difference was found between the CH and WBC methods in terms of overall results, weak outcomes in some cognitive subdomains in the CH group were noteworthy. Larger sample sizes and prospective studies are needed.

Target temperature management (TTM) is a neuroprotective strategy widely used in acute brain injury. However, its real-world implementation remains highly heterogenous and the clinical implications of different temperature targets and treatment durations are not well defined. This study aimed to describe real-world TTM practices and to explore associations between TTM characteristics, coagulopathy, and in-hospital mortality in patients with acute brain injury. We retrospectively analyzed 180 patients who underwent TTM between January 2011 and December 2024 at a single tertiary medical center. Patients diagnosed with acute brain injury, including aneurysmal subarachnoid hemorrhage, traumatic brain injury (TBI), intracerebral hemorrhage, or acute infarction, were included. Clinical variables, TTM parameters, complications, comorbidities, and in-hospital outcomes were analyzed. Univariable and multivariable analyses were conducted to identify factors associated with in-hospital mortality and TTM-related coagulopathy. In-hospital mortality occurred in 78 patients (43.3%). In multivariable analysis, post-cardiac arrest state (odds ratio [OR] = 3.99, p = 0.003) and coagulopathy during TTM (OR = 5.31, p = 0.005) were significantly associated with increased in-hospital mortality. Coagulopathy occurred in 21 (11.7%) patients and was significantly associated with type of injury, which showed it was most prevalent in TBI. Prolonged duration of TTM was not associated with an increased risk of coagulopathy and was associated with lower in-hospital mortality (OR = 0.30, p < 0.001). Injury subtype demonstrated significant heterogeneity in mortality risk and was retained as a covariate in the final multivariable model. In this real-world cohort, TTM practices varied substantially across acute brain injury subtypes. Coagulopathy was associated with increased in-hospital mortality and occurred more frequently in patients with TBI. Prolonged TTM was associated with lower in-hospital mortality. However, this finding should be interpreted cautiously given the potential for survivorship bias. Mortality risk differed across injury subtypes. These findings suggest that the clinical context and underlying injury type should be considered when applying TTM in patients with acute brain injury.

Shivering is a common complication of targeted temperature management (TTM), which could undermine its neuroprotective benefits by increasing cerebral oxygen consumption and metabolic demand. Buspirone, a 5-HT1A receptor partial agonist, is incorporated into many antishivering protocols for TTM following cardiac arrest, despite limited evidence supporting its efficacy in critically ill patients. We conducted a targeted literature review using PubMed to assess the evidence in favor of the use of buspirone in antishivering protocols during TTM. Experimental, physiological, and clinical studies were reviewed with emphasis placed on study design, patient population, and relevance to critically ill individuals undergoing TTM. Experimental studies in animals and healthy human volunteers show that buspirone can modestly lower core temperature or shivering thresholds. Two small studies (n = 8 each) in healthy male volunteers demonstrated that buspirone reduced the shivering threshold by approximately 0.7°C. A retrospective cohort study (n = 131) in post-cardiac arrest patients showed a reduction in shivering with a multidrug protocol including buspirone, but the independent contribution of buspirone could not be isolated. No randomized controlled trials have evaluated buspirone’s efficacy as a standalone antishivering agent in critically ill patients. Current evidence to support the buspirone’s use in antishivering protocols is limited and largely extrapolated from noncritical care settings. Given that most patients undergoing TTM already receive sedatives and analgesics with more potent antishivering effects, the incremental benefit of buspirone remains unproven. Furthermore, it adds to the already high burden of polypharmacy in ICU patients and could, in theory, increase the risk of serotonin syndrome. Randomized trials comparing protocols with and without buspirone are needed to determine its clinical utility.

Core body temperature reflects core heat content, which is determined by the balance of heat production and heat loss. Studies and interventions focusing on temperature rarely measure metabolic heat production and heat loss. This study tests whether net heat balance (NHB) in humans can predict core temperature changes and secondarily whether NHB combined with skin surface temperatures (ST) can estimate core temperature. We conducted a laboratory study of healthy volunteers cooled with gel-adhesive circulating water pads with or without treatment with a drug (dexmedetomidine) to prevent shivering. We measured heat flux on the forehead, deltoid, anterior abdominal wall, and above the knee. We measured energy expenditure (W) using indirect calorimetry and core temperature (T) using deep gastrointestinal temperature. Thirteen participants (age 20–51 years; height 160–188 cm; mass 61–101 kg) participated in 21 protocol days. Mean (standard deviation [SD]) NHB ranged from +14 (26) W at baseline to −56 (25) W with drug and cooling pads. NHB predicted change in core temperature 60 minutes later (lagged regression slope: 0.33°C/100W; 95% confidence interval [CI] [0.2, 0.5]) (pseudo r² = 12.81%). Forehead ST had the narrowest limits of agreement [−2.6°C, −2.4°C] for predicting core temperature with a mean bias of −2.5°C. In conclusion, NHB of −100W predicts a 0.33°C/60 minutes decrease in core temperature. Forehead temperature is the most consistent peripheral site to predict core temperature. While a cooling device increases heat loss, energy expenditure (EE) also rises with surface cooling, minimizing NHB, and core temperature change unless a drug is utilized to suppress the increase in EE.

To perform a systematic review and meta-analysis to examine the association between persistent pulmonary hypertension (PPHN) and receipt of therapeutic hypothermia (TH), compared to those who did not receive TH, among infants with moderate or severe hypoxic-ischemic encephalopathy (HIE). Systematic review and meta-analysis based on Ovid, Medline, Embase and Cochrane central searches from 01/01/2000 to 31/03/2025. We included only randomized control trials for meta-analysis and followed international guidelines for conducting systematic reviews. The primary outcome of the study was PPHN in infants undergoing TH for moderate to severe HIE. Among 185 articles identified using search strategy, 19 articles were assessed for eligibility. Eight randomized control trials (RCTs) met the inclusion criteria, and seven were included in meta-analysis. A random effects model used for the outcome of PPHN, comparing TH with NT or usual care, involving a pooled population of 1006 infants across seven studies. The relative risk of PPHN for TH versus NT was 1.13 (95% confidence interval 0.81 to 1.57). We noted risk of bias in the blinding of participants across included RCTs. We assessed nine observational studies and performed a narrative review. We noted that a considerable number of infants developed PPHN across TH and NT groups. We did not find evidence of an association between TH and PPHN in infants with moderate to severe HIE, although a considerable number of infants developed PPHN across both groups. We suggest that clinicians should be aware of the risk of PPHN to allow prompt investigation and management.