Cooling Activity is Associated with Neurological Outcome in Patients with Severe Cerebrovascular Disease Undergoing Endovascular Temperature Control

Fever Prevention in Patients With Acute Vascular Brain Injury: The INTREPID Randomized Clinical Trial

Importance

Fever is associated with worse outcomes in patients with stroke, but whether preventing fever improves outcomes is unclear.

Objective

To determine whether fever prevention after acute vascular brain injury is achievable and impacts functional outcome.

Design, Setting, and Participants

Open-label randomized clinical trial with blinded outcome assessment that enrolled 686 of 1176 planned critically ill patients with stroke at 43 intensive care units in 7 countries from March 2017 to April 2021 (last date of follow-up was May 12, 2022).

Intervention

Patients randomized to fever prevention (n = 339) were targeted to 37.0 °C for 14 days or intensive care unit discharge using an automated surface temperature management device. Standard care patients (n = 338) received standardized tiered fever treatment on occurrence of temperature of 38 °C or greater.

Main Outcomes and Measures

Primary outcome was daily mean fever burden: the area under the temperature curve above 37.9 °C (total fever burden) divided by the total number of hours in the acute phase, multiplied by 24 hours (°C-hour). The principal secondary outcome was 3-month functional recovery by shift analysis of the 6-category modified Rankin Scale, which is scored from 0 (no symptoms) to 6 (death). Major adverse events included death, pneumonia, sepsis, and malignant cerebral edema.

Results

Enrollment was stopped after a planned interim analysis demonstrated futility of the principal secondary end point. In total, 686 patients were enrolled, and 9 were consented but not randomized, leaving a primary analysis population of 677 patients (254 ischemic stroke, 223 intracerebral hemorrhage, 200 subarachnoid hemorrhage; 345 were female [51%]; median age, 62 years) with 433 (64%) completing the study through 12 months. Daily mean (SD) fever burden was significantly lower in the fever prevention group (0.37 [1.0] °C-hour; range, 0.0-8.0 °C-hour) compared with the standard care group (0.73 [1.1] °C-hour; range, 0.0-10.3 °C-hour) (difference, -0.35 [95% CI, -0.51 to -0.20]; P < .001). Between-group differences for the primary outcome by stroke subtype were -0.10 (95% CI, -0.35 to 0.15) for ischemic stroke, -0.50 (95% CI, -0.78 to -0.22) for intracerebral hemorrhage, and -0.52 (95% CI, -0.81 to -0.23) for subarachnoid hemorrhage (all P < .001 by Wilcoxon rank-sum test). There was no significant difference in functional recovery at 3 months (median modified Rankin Scale score, 4.0 vs 4.0, respectively; odds ratio for a favorable shift in functional outcome, 1.09 [95% CI, 0.81 to 1.46]; P = .54). Major adverse events occurred in 82.2% of participants in the fever prevention group vs 75.9% in the standard care group, including 33.8% vs 34.5% for infections, 14.5% vs 14.0% for cardiac disorders, and 24.5% vs 20.5% for respiratory disorders.

Conclusions and Relevance

In patients with acute vascular brain injury, preventive normothermia using an automated surface temperature management device effectively reduced fever burden but did not improve functional outcomes.

Trial Registration

ClinicalTrials.gov Identifier: NCT02996266.

Impact of Fever Prevention in Brain-Injured Patients (INTREPID): Study Protocol for a Randomized Controlled Trial

BACKGROUND

Multiple studies demonstrate that fever/elevated temperature is associated with poor outcomes in patients with vascular brain injury; however, there are no conclusive studies that demonstrate that fever prevention/controlled normothermia is associated with better outcomes. The primary objective of the INTREPID (Impact of Fever Prevention in Brain-Injured Patients) trial is to test the hypothesis that fever prevention is superior to standard temperature management in patients with acute vascular brain injury.

METHODS

INTREPID is a prospective randomized open blinded endpoint study of fever prevention versus usual care in patients with ischemic or hemorrhagic stroke. The fever prevention intervention utilizes the Arctic Sun System and will be compared to standard care patients in whom fever may spontaneously develop. Ischemic stroke, intracerebral hemorrhage or subarachnoid hemorrhage patients will be included within disease-specific time-windows. Both awake and sedated patients will be included, and treatment is initiated immediately upon enrollment. Eligible patients are expected to require intensive care for at least 72 h post-injury, will not be deemed unlikely to survive without severe disability, and will be treated for up to 14 days, or until deemed ready for discharge from the ICU, whichever comes first. Fifty sites in the USA and worldwide will participate, with a target enrollment of 1176 patients (1000 evaluable). The target temperature is 37.0 °C. The primary efficacy outcome is the total fever burden by °C-h, defined as the area under the temperature curve above 37.9 °C. The primary secondary outcome, on which the sample size is based, is the modified Rankin Scale Score at 3 months. All efficacy analyses including the primary and key secondary endpoints will be primarily based on an intention-to-treat population. Analysis of the as-treated and per protocol populations will also be performed on the primary and key secondary endpoints as sensitivity analyses.

DISCUSSION

The INTREPID trial will provide the first results of the impact of a pivotal fever prevention intervention in patients with acute stroke ( www.clinicaltrials.gov ; NCT02996266; registered prospectively 05DEC2016).

Evidence-Based Review of Clinical Trials in Neurocritical Care

Neurocritical care is a rapidly growing specialty of complex care for the critically ill patient with neurological injury. This rapid growth has led to an increase in the number of important clinical trials to guide clinical practice and evidence-based care of the critically ill patient with neurological injury. Specialty-trained critical care nurses and advanced practice providers are integral members of neurocritical care teams and must remain informed about pivotal trials shaping practice recommendations. This article presents a summary of recent trials that have affected current practice and influenced care recommendations in the neurocritical care setting.

Targeted temperature management in neurological intensive care unit

Targeted temperature management (TTM) shows the most promising neuroprotective therapy against hypoxic/ischemic encephalopathy (HIE). In addition, TTM is also useful for treatment of elevated intracranial pressure (ICP). HIE and elevated ICP are common catastrophic conditions in patients admitted in Neurologic intensive care unit (ICU). The most common cause of HIE is cardiac arrest. Randomized control trials demonstrate clinical benefits of TTM in patients with post-cardiac arrest. Although clinical benefit of ICP control by TTM in some specific critical condition, for an example in traumatic brain injury, is still controversial, efficacy of ICP control by TTM is confirmed by both in vivo and in vitro studies. Several methods of TTM have been reported in the literature. TTM can apply to various clinical conditions associated with hypoxic/ischemic brain injury and elevated ICP in Neurologic ICU.

Normothermia and Stroke

OPINION STATEMENT

In the past two decades, there has been much focus on the adverse effect of fever on neurologic outcome, the benefits of hypothermia on functional outcomes, and the interplay of associated complications. Despite decades of experience regarding randomized, safety and feasibility, case-controlled, retrospective studies, there has yet to be a large, randomized, multicenter, clinical trial with the appropriate power to address the potential benefits of targeted temperature modulation compared to hypothermia alone. What remains unanswered is the appropriate timing of initiation, duration, rewarming speed, and depth of targeted temperature management. We learn from the cardiac arrest literature that there is a neuroprotective value to hypothermia and, most recently, near normothermia (36 °C) as well. We have also established that increased depths of cooling are associated with increases in shivering, which warrant more aggressive pharmacologic management. Normothermia also has the advantage of allowing for more rapid clearance of sedating medications and less confounding of neuroprognostication. More difficult to quantify is the increased nursing and patient care complexity associated with moderate hypothermia compared to normothermia. It remains crucial, for those patients who are being considered for hypothermia/normothermia, to be cared for in an experienced ICU, driven under protocol, with aggressive shivering management and an expectation and acceptance of the complications associated with targeted temperature management. If targeted temperature management is not of consideration, then aggressive fever control should be undertaken pharmacologically and non-invasively, as they have been shown to be safe.