Safety and Efficacy of Bladder Temperature Monitoring-Guided Targeted Temperature Management in Patients With Severe : A Multicenter Randomized Controlled Trial

Neurogenic fever, a non-infectious febrile condition, is relatively common following severe brain injuries such as intracerebral hemorrhage, aneurysmal subarachnoid hemorrhage, and acute ischemic stroke. Early-onset fever may represent a systemic response to the brain injury itself, whereas late-onset fever is often attributable to severe stroke complications, including infection and deep vein thrombosis (DVT). Fever is positively correlated with illness severity. Substantial evidence confirms that hyperthermia significantly increases the risk of complications-such as rebleeding, exacerbated cerebral edema, seizures-and mortality in patients with intracerebral hemorrhage, and is associated with poor prognosis. Studies have found that mortality and voluntary discharge rates in stroke patients with extreme hyperthermia are six times higher than those in patients with normal body temperature. This underscores the critical importance of timely and effective temperature control and management in stroke patients, which has been shown to reduce mortality and improve neurological outcomes.

Body temperature is a vital sign and a key indicator of health status. Under the regulation of the hypothalamic thermoregulatory center, it fluctuates within a narrow range; deviations beyond this range suggest potential abnormalities [8]. In severe ICH patients, temperature fluctuations not only reflect systemic stress but also serve as a sensitive indicator of intracranial pathological changes, such as hematoma expansion, progressing cerebral edema, and secondary brain injury. However, a critical issue in current clinical practice is the frequent failure to detect temperature changes in severe ICH patients promptly. Typically, significant temperature elevations or reductions are only recognized when they reach extreme levels. This makes it exceptionally difficult to identify the onset of temperature changes, the timing of peaks/troughs, and the effective time of interventions, severely hindering the early recognition of clinical deterioration and timely intervention, potentially missing critical windows for improving outcomes. Therefore, continuous temperature monitoring is crucial for severe ICH patients, particularly given their high fever incidence and elevated risk of secondary brain injury; fever must be identified and managed aggressively upon onset.

Intracranial temperature (ICT) can be measured via direct (e.g., intraparenchymal, intraventricular, subdural catheters) or indirect methods. However, direct measurement is invasive, its application is limited in ICH patients with coagulopathies or high rebleeding risks, and it carries additional risks of hemorrhage or infection. When direct ICT monitoring probes or devices are unavailable, it is recommended to use core temperature measurements from sites that closely approximate and are relatively stable compared to brain temperature. Core temperature measurement sites include the tympanic membrane, temporal artery, rectum, bladder, esophagus, and pulmonary artery. The temperature monitored via a pulmonary artery catheter is considered closest to the true core temperature. Expert consensus on targeted temperature management (TTM) in neurocritical care recommends a preference for brain temperature measurement, followed by esophageal and bladder temperatures. However, esophageal temperature measurement is mildly invasive. Although bladder temperature is recommended by consensus and is known to reliably reflect core temperature trends, in-depth research and direct evidence regarding its application specifically in the high-risk ICH population, particularly rigorous comparative data against the gold standard of intracranial temperature, remain notably scarce.

Given the high fever rate in severe ICH patients, the decisive impact of temperature management on prognosis, the limitations of existing core temperature monitoring methods (especially esophageal) in this population, and the lack of high-quality evidence for bladder temperature monitoring, exploring an accurate, reliable, and practical method for continuous core temperature monitoring suitable for severe ICH patients is of urgent clinical significance. Bladder temperature monitoring offers significant advantages: its readings closely approximate intracranial core temperature trends, enabling real-time reflection of patient temperature fluctuations; it boasts high measurement accuracy and relatively simple operation; it can be implemented via the indwelling urinary catheter routinely placed in severe ICH patients (for monitoring urine output and managing retention), without adding significant nursing workload, avoiding additional invasive procedures, and minimizing patient disturbance, sleep disruption, and treatment interference, while allowing for stable, prolonged placement. More importantly, the continuous monitoring capability of bladder temperature can empower clinicians to grasp the dynamic temperature changes in severe ICH patients in real-time, providing crucial information for the early detection of fever and potential clinical deterioration (e.g., infection, hematoma expansion, worsening cerebral edema), thereby securing a valuable early intervention time window for implementing neuroprotective strategies and complication prevention.

In recent years, bladder temperature monitoring has gained attention in temperature management due to its relative operational simplicity, close approximation to core temperature, and suitability for continuous monitoring. However, current research on using bladder temperature monitoring to guide TTM in neurocritical care patients, specifically those with spontaneous intracerebral hemorrhage, is relatively limited. Existing studies often focus on investigating the impact of TTM itself on patient outcomes or validating the correlation between bladder temperature and traditional monitoring techniques. The updated consensus guidelines from the Neuroprotective Therapy Consensus Review Group emphasize that core temperature is the most important surrogate for intracranial temperature and note that implementing TTM requires reliance on technology capable of real-time, continuous temperature monitoring to precisely regulate body temperature and adjust treatment strategies promptly.