Therapeutic hypothermia reduces middle cerebral artery flow velocity in patients with severe aneurysmal subarachnoid hemorrhage

Hypothermia on the first day of ICU admission leads to increased in-hospital mortality in patients with subarachnoid hemorrhage

The relationship between early spontaneous hypothermia and adverse clinical outcomes in patients with subarachnoid hemorrhage (SAH) has not been paid much attention. We designed this retrospective cohort study to determine this relationship by analyzing the association between the lowest body temperature (T-lowest) on the first day of ICU admission and in-hospital mortality. In this study, 550 participants with non-traumatic SAH were chosen from the Medical Information Mart for Intensive Care (MIMIC)-IV database. Multivariate Cox regression analysis showed that T-lowest was nonlinearity correlated with in-hospital mortality (HR = 0.72, 95% CI: 0.59-0.86, p < 0.001). We divided the T-lowest into quartile groups. In comparison to reference group Q1 (31.30-36.06 ℃), group Q3 (36.56-36.72 ℃) had a 50% lower risk of death in the hospital (HR: 0.5, 95% CI: 0.28-0.87, p = 0.014). We further confirmed the curve-like relationship between T-lowest and in-hospital mortality using restricted cubic splines. The mortality is lowest when the T-lowest is close to 36.5 °C, and the risk of death is increased when the temperature is lower or higher than that. Our study demonstrates that in-hospital mortality is associated with T-lowest. Patients with non-traumatic SAH are at increased risk of death if their body temperature on the first day of ICU admission is too low.

Targeted Temperature Management for Poor Grade Aneurysmal Subarachnoid Hemorrhage: A Pilot Study

OBJECTIVE

We assessed the effectiveness and safety of target temperature management (TTM) in treating patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH). The primary objective was to evaluate the neurological outcome at 3 months. Secondary objectives were to assess mortality, delayed cerebral ischemia, cerebral edema, hydrocephalus, midline shift, and laboratory indicators related to TTM.

METHODS

A single-blind, nonrandomized controlled trial was conducted. After admission, patients with poor-grade aSAH (Hunt-Hess scores IV ∼ V) were assigned to a TTM group or a control group in a 1:1 ratio. TTM with core temperatures ranging from 36°C to 37°C was performed immediately and maintained until microclipping or endovascular embolization. Subsequently, rapid induction to 33°C ∼ 35°C was carried out and maintained for 3 to 5 days. Then, the patients underwent slow rewarming to 36°C ∼ 37°C and maintained at that temperature for a minimum of 48 hours.

RESULTS

Sixty patients (30 treated with TTM and 30 with standard treatment) were included in the study. At 3 months, a favorable prognosis (modified Rankin scale score 0 to 3) was significantly higher in the TTM group than in the control group (n = 14, 46.7% vs. n = 6, 20.0%, P = 0.028). Adjusted multivariate logistics regression analysis indicated that TTM (odds ratio = 0.20, 95% confidence interval: 0.05-0.77, P = 0.019) reduced the number of unfavorable prognoses 3 months after admission.

CONCLUSIONS

This study demonstrated the effectiveness and safety of TTM in patients with poor-grade aSAH, and its implementation improved neurological outcomes. Multicenter randomized controlled studies with a large number of patients are needed to confirm these observations.

Targeted Temperature Management for Severe Subarachnoid Hemorrhage Using Endovascular and Surface Cooling Systems: A Nonrandomized Interventional Study Using Historical Control

BACKGROUND

Although targeted temperature management (TTM) may mitigate brain injury for severe subarachnoid hemorrhage (SAH), rebound fever correlates with poor outcomes.

OBJECTIVE

To study the effect of endovascular TTM after rewarming from initial surface cooling during a high-risk period for delayed cerebral ischemia.

METHODS

We studied patients with World Federation of Neurological Surgeons grade V SAH before and after the introduction of endovascular TTM. Both groups (36 patients each) were treated with TTM at 34 °C with conventional surface cooling immediately after SAH diagnosis, together with emergency aneurysm repair. When rewarmed to 36 °C, around 7 days later, the study group underwent TTM at 36 to 38 °C for 7 days with an endovascular cooling system. The control group was treated with antipyretics.

RESULTS

Sex, age, Glasgow Coma Scale score, modified Fisher computed tomography classification, aneurysm location, and treatment methods were not different between the study and control groups. Differences were detected in the incidence of fever >38 °C (13 vs 26 patients, P = .0021), duration of fever >38 °C (4.1 vs 18.8 hours, P = .0021), incidence of vasospasm-related cerebral infarction (17% vs 42%, P = .037), and the likelihood of excellent outcomes (0 and 1 on a modified Rankin Scale) at 6 months (42% vs 17%, P = .037). In endovascular TTM, shivering occurred more frequently in patients with better outcomes, requiring aggressive treatment to avoid fever.

CONCLUSION

Endovascular TTM at 36 to 38 °C after surface cooling was feasible and safely performed in patients with severe SAH. Combined TTM for 2 weeks was associated with a lower incidence of vasospasm-related infarction and may improve outcomes.

Depolarization time and extracellular glutamate levels aggravate ultraearly brain injury after subarachnoid hemorrhage

Early brain injury after aneurysmal subarachnoid hemorrhage (SAH) worsens the neurological outcome. We hypothesize that a longer duration of depolarization and excessive release of glutamate aggravate neurological outcomes after SAH, and that brain hypothermia can accelerate repolarization and inhibit the excessive release of extracellular glutamate and subsequent neuronal damage. So, we investigated the influence of depolarization time and extracellular glutamate levels on the neurological outcome in the ultra-early phase of SAH using a rat injection model as Experiment 1 and then evaluated the efficacy of brain hypothermia targeting ultra-early brain injury as Experiment 2. Dynamic changes in membrane potentials, intracranial pressure, cerebral perfusion pressure, cerebral blood flow, and extracellular glutamate levels were observed within 30 min after SAH. A prolonged duration of depolarization correlated with peak extracellular glutamate levels, and these two factors worsened the neuronal injury. Under brain hypothermia using pharyngeal cooling after SAH, cerebral perfusion pressure in the hypothermia group recovered earlier than that in the normothermia group. Extracellular glutamate levels in the hypothermia group were significantly lower than those in the normothermia group. The early induction of brain hypothermia could facilitate faster recovery of cerebral perfusion pressure, repolarization, and the inhibition of excessive glutamate release, which would prevent ultra-early brain injury following SAH.

Lower Body Temperature Independently Predicts Delayed Cerebral Infarction in the Elderly With Ruptured Intracranial Aneurysm

Purpose: To assess the correlation between admission body temperature and delayed cerebral infarction in elderly patients with ruptured intracranial aneurysm (IA).

Methods: Patients with ruptured IA diagnosed between 2012 and 2020 were retrospectively analyzed. Patients were divided into a non-infarction and an infarction group based on the presence of cerebral infarction after treatment. The demographic and clinical information of the patients was gathered. Outcomes at the 3-month follow-up were assessed using the modified Rankin Scale. Correlation between admission body temperature and cerebral infarction was assessed using Spearman's rank correlation coefficient. A receiver operating characteristic (ROC) curve was used to assess the specificity and sensitivity of admission body temperature to predict cerebral infarction.

Results: A total of 426 patients (142 men and 284 women) with ruptured IA were enrolled. Elderly patients with cerebral infarction (12.4%) had a lower body temperature at admission (p < 0.001), higher prevalence of hypertension and diabetes (p = 0.051 and p = 0.092, respectively), and higher rate of poor outcomes (p < 0.001). Admission body temperature was independently associated with cerebral infarction (odds ratio [OR] = 5.469, p < 0.001); however, hypertension (OR = 0.542, p = 0.056), diabetes (OR = 0.750, p = 0.465), and aneurysm size (OR = 0.959, p = 0.060) showed no association. An inverse correlation between admission body temperature and the incidence of cerebral infarction was observed (Spearman's r =−0.195, p < 0.001). An admission body temperature of 36.6°C was able to distinguish infarction and non-infarction patients. The area under the ROC curve was 0.669 (specificity, 64.15%; sensitivity, 81.50%; p < 0.001).

Conclusions: Lower body temperature at admission (≤36.6°C) is an independent predictor of delayed cerebral infarction in elderly patients who have undergone treatment for ruptured IA. Therefore, it could be a risk factor for adverse outcomes of IA.

Neuroprotective Strategies in Aneurysmal Subarachnoid Hemorrhage (aSAH)

Aneurysmal subarachnoid hemorrhage (aSAH) remains a disease with high mortality and morbidity. Since treating vasospasm has not inevitably led to an improvement in outcome, the actual emphasis is on finding neuroprotective therapies in the early phase following aSAH to prevent secondary brain injury in the later phase of disease. Within the early phase, neuroinflammation, thromboinflammation, disturbances in brain metabolism and early neuroprotective therapies directed against delayed cerebral ischemia (DCI) came into focus. Herein, the role of neuroinflammation, thromboinflammation and metabolism in aSAH is depicted. Potential neuroprotective strategies regarding neuroinflammation target microglia activation, metalloproteases, autophagy and the pathway via Toll-like receptor 4 (TLR4), high mobility group box 1 (HMGB1), NF-κB and finally the release of cytokines like TNFα or IL-1. Following the link to thromboinflammation, potential neuroprotective therapies try to target microthrombus formation, platelets and platelet receptors as well as clot clearance and immune cell infiltration. Potential neuroprotective strategies regarding metabolism try to re-balance the mismatch of energy need and supply following aSAH, for example, in restoring fuel to the TCA cycle or bypassing distinct energy pathways. Overall, this review addresses current neuroprotective strategies in aSAH, hopefully leading to future translational therapy options to prevent secondary brain injury.

Targeted temperature management at 33 degrees Celsius in patients with high-grade aneurysmal subarachnoid hemorrhage: a protocol for a multicenter randomized controlled study

Background

Studies on the use of therapeutic hypothermia (TH) to improve the outcome of high-grade aneurysmal subarachnoid hemorrhage (aSAH), show promising, though conflicting results because of the lack of high-quality trials. The aim of this study is to evaluate the safety and efficacy of TH (maintaining bladder temperature at 33 °C for ≥72 h) to treat patients with high-grade aSAH (Hunt-Hess grade IV-V).

Methods

A multicenter, randomized, controlled clinical trial will be conducted for October 2020 to September 2024 involving 10 clinics. Patients who meet the inclusion criteria will be randomized 1:1 to a TH group and a normothermia group. The trial will enroll 96 participants in TH group and normothermia one, respectively. The trial was registered with ClinicalTrials.gov (NCT03442608) on February 22, 2018. Following conventional treatment for aSAH, patients will undergo either TH for at least 72 h or normothermia. The primary endpoint is the Glasgow outcome scale at 6 months after bleeding. The secondary endpoints are: (I) mortality at 6 months after bleeding; (II) intracranial pressure; (III) intensive care unit stay; and (IV) hospital stay. The safety endpoints include neurological, infectious, intestinal, circulatory, coagulation, and bleeding complications, electrolyte disorders, and other complications.

Discussion

If the study hypothesis is confirmed, TH at 33 °C in patients with high-grade aSAH may become a promising treatment strategy for improving 6-month outcome.

Trial registration

The trial has been registered at ClinicalTrials.gov (ID: NCT03442608).

[Treatment options for acute respiratory distress syndrome in neurointensive care. Individual management due to enhanced neuromonitoring? : A case report series]

Severe pulmonary impairment can occur after traumatic brain injury or stroke. The resulting brain-lung interactions represent key points for the treatment and the subsequent outcome of the patient. Established treatment approaches, such as permissive hypercapnia and prone positioning, present the intensive care physician with divergent treatment goals in these patients with partially increased intracranial pressure. This case report series shows the instrument-based and noninstrument-based options for the treatment of acute respiratory distress syndrome (ARDS) in the simultaneous presence of intracranial pathologies. This includes equipment based therapies using extracorporeal CO₂ elimination, special positioning maneuvers in specially designed hospital beds and positional maneuvers, such as prone positioning. With enhanced neuromonitoring it is possible to optimally adapt treatment measures focused on the lungs early and before secondary damage to the brain.

Changes of Endothelin-1 and Nitric Oxide Systems in Brain Tissue During Mild Hypothermia in a Porcine Model of Cardiac Arrest

BACKGROUND

Our previous study found that mild hypothermia (MH) after resuscitation reduced cerebral microcirculation, but the mechanism was not elucidated. The aim of this study was to clarify changes of endothelin-1 (ET-1) and nitric oxide (NO) systems in brain tissue during hypothermia after resuscitation.

METHODS

Twenty-six domestic male Beijing Landrace pigs were used in this study. MH was intravascularly induced 1 h after resuscitation from 8-min ventricular fibrillation. Core temperature was reduced to 33 °C and maintained until 8 h after resuscitation, and then animals were euthanized. ET-1 and NO levels in brain tissue and peripheral plasma were measured. Expression of endothelin-converting enzyme-1 (ECE-1), endothelin A receptor (ET-AR), endothelin-B receptor, and nitric oxide synthase (NOS) in brain tissue was determined by Western blot analysis.

RESULTS

Compared with non-hypothermia (NH) treatment, MH after resuscitation significantly increased the level of endothelin-1 and reduced the level of NO in peripheral blood and brain tissue. Cerebral expression of ECE-1 and ET-AR was significantly increased during MH after resuscitation. Moreover, MH significantly decreased inducible NOS expression compared with the NH group.

CONCLUSIONS

The ET-1 system is activated, while inducible NOS is inhibited in brain tissue during MH after resuscitation.

Targeted Temperature Management for Subarachnoid Hemorrhage: Excellent Outcome After Severe Vasospasm-A Case Series

Targeted temperature management (TTM) might improve outcome of patients with severe subarachnoid hemorrhage (SAH) in which vasospasm, delayed cerebral ischemia (DCI), and increased intracranial pressure (ICP) are frequent and severe complications. A series of patients (n = 3) with severe aneurysmatic SAH were treated by TTM if they developed ICP crisis and/or severe vasospasm diagnosed by angiography. Once these complications were detected, body core temperature (BCT) was rapidly decreased to 35°C or 33°C, if necessary. BCT induced and maintained by surface cooling remained at the desired level for at least 72 hours. Rewarming was performed by 1°C, only if the target parameters ICP and velocities in the serial Doppler sonography indicating macrovascular vasospasm improved to regular levels. In case of increase of ICP or middle cerebral arteries velocities BCT was decreased again to the last effective level. The patients developed vasospasm between days 6 and 12 after SAH. All aneurysms were treated by coiling. BCT was reduced between days 6 and 12 after SAH. Total duration of BCT <36.5°C was between 5.5 and 8 days. It remained <35°C for 4-6 days, and at 33°C for 3 days on average. ICP could be sufficiently controlled in all patients, because no ICP crisis was observed during TTM and after rewarming. Two patients developed minor DCI. Side effects of prolonged ventilation of 7-18 days included pneumonia for two patients that could be treated sufficiently. Other complications were one case of ventriculitis and two temporary deliriums. Outcome of the patients was good because no focal neurological symptoms could be detected after rehabilitation. TTM represents a promising treatment approach for severe SAH in which standard treatment is often limited and experimental. It deserves further clinical investigation in a larger cohort.

Nutritional and Bioenergetic Considerations in Critically Ill Patients with Acute Neurological Injury

The brain, due to intensive cellular processes and maintenance of electrochemical gradients, is heavily dependent on a constant supply of energy. Brain injury, and critical illness in general, induces a state of increased metabolism and catabolism, which has been proven to lead to poor outcomes. Of all the biochemical interventions undertaken in the ICU, providing nutritional support is perhaps one of the most undervalued, but potentially among the safest, and most effective interventions. Adequate provisions of calories and protein have been shown to improve patient outcomes, and guidelines for the nutritional support of the critically ill patient are reviewed. However, there are no such specific guidelines for the critically ill patient with neurological injury. Patients with primary or secondary neurological disorders are frequently undernourished, while data suggest this population would benefit from early and adequate nutritional support, although comprehensive clinical evidence is lacking. We review the joint recommendations from the Society for Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition, as they pertain to neurocritical care, and assess the recommendations for addressing nutrition in this patient population.

Feasibility and Safety of Mild Therapeutic Hypothermia in Poor-Grade Subarachnoid Hemorrhage: Prospective Pilot Study

Therapeutic hypothermia (TH) improves the neurological outcome in patients after cardiac arrest and neonatal hypoxic brain injury. We studied the safety and feasibility of mild TH in patients with poor-grade subarachnoid hemorrhage (SAH) after successful treatment. Patients were allocated randomly to either the TH group (34.5°C) or control group after successful clipping or coil embolization. Eleven patients received TH for 48 hours followed by 48 hours of slow rewarming. Vasospasm, delayed cerebral ischemia (DCI), functional outcome, mortality, and safety profiles were compared between groups. We enrolled 22 patients with poor-grade SAH (Hunt & Hess Scale 4, 5 and modified Fisher Scale 3, 4). In the TH group, 10 of 11 (90.9%) patients had a core body temperature of < 36°C for > 95% of the 48-hour treatment period. Fewer patients in the TH than control group (n = 11, each) had symptomatic vasospasms (18.1% vs. 36.4%, respectively) and DCI (36.3% vs. 45.6%, respectively), but these differences were not statistically significant. At 3 months, 54.5% of the TH group had a good-to-moderate functional outcome (0-3 on the modified Rankin Scale [mRS]) compared with 9.0% in the control group (P = 0.089). Mortality at 1 month was 36.3% in the control group compared with 0.0% in the TH group (P = 0.090). Mild TH is feasible and can be safely used in patients with poor-grade SAH. Additionally, it may reduce the risk of vasospasm and DCI, improving the functional outcomes and reducing mortality. A larger randomized controlled trial is warranted.

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.

Endovascular Cooling Catheter for Selective Brain Hypothermia: An Animal Feasibility Study of Cooling Performance

BACKGROUND AND PURPOSE

Therapeutic hypothermia represents a promising neuroprotective treatment in acute ischemic stroke. Selective cerebral hypothermia applied early, prior to and during endovascular mechanical recanalization therapy, may be beneficial in the critical phase of reperfusion. We aimed to assess the feasibility of a new intracarotid cooling catheter in an animal model.

MATERIALS AND METHODS

Nine adult sheep were included. Temperature probes were introduced into the frontal and temporal brain cortices bilaterally. The cooling catheter system was introduced into a common carotid artery. Selective blood cooling was applied for 180 minutes. Systemic and local brain temperatures were measured during cooling and rewarming. Common carotid artery diameters and flow were measured angiographically and by Doppler sonography.

RESULTS

The common carotid artery diameter was between 6.7 and 7.3 mm. Common carotid artery blood flow velocities increased moderately during cooling and after catheter removal. Maximum cerebral cooling in the ipsilateral temporal cortex was -4.7°C (95% CI, -5.1 to -4.0°C). Ipsilateral brain temperatures dropped significantly faster and became lower compared with the contralateral cortex with maximum temperature difference of -1.3°C (95% CI, -1.5 to -1.0°C; P < .0001) and compared with systemic temperature (-1.4°C; 95% CI, -1.7 to -1.0°C; P < .0001).

CONCLUSIONS

Sheep proved a feasible animal model for the intracarotid cooling catheter. Fast induction of selective mild hypothermia was achieved within the cooled cerebral hemisphere, with stable temperature gradients in the contralateral brain and systemic blood. Further studies are required to demonstrate any therapeutic benefit of selective cerebral cooling in a stroke model.

Rescue therapy for refractory vasospasm after subarachnoid hemorrhage

Vasospasm and delayed cerebral ischemia remain to be the common causes of increased morbidity and mortality after aneurysmal subarachnoid hemorrhage. The majority of clinical vasospasm responds to hemodynamic augmentation and direct vascular intervention; however, a percentage of patients continue to have symptoms and neurological decline. Despite suboptimal evidence, clinicians have several options in treating refractory vasospasm in aneurysmal subarachnoid hemorrhage (aSAH), including cerebral blood flow enhancement, intra-arterial manipulations, and intra-arterial and intrathecal infusions. This review addresses standard treatments as well as emerging novel therapies aimed at improving cerebral perfusion and ameliorating the neurologic deterioration associated with vasospasm and delayed cerebral ischemia.

Postoperative ICU management of patients after subarachnoid hemorrhage

PURPOSE OF REVIEW

This article reviews recent advances in the postoperative ICU management of patients after subarachnoid hemorrhage (SAH), especially with regards to hemodynamic management, methods of improving neurological outcomes, and management of cardiac and pulmonary complications.

RECENT FINDINGS

Several hemodynamic monitors and parameters may be useful for guiding volume therapy, including cardiac output, stroke volume variation monitoring, and global end-diastolic volume index. Early goal-directed hemodynamic therapy after SAH has recently been shown to improve clinical outcomes in patients with a poor clinical grade or coexisting cardiopulmonary complications. Recent laboratory and imaging modalities are being developed to identify patients at risk for developing vasospasm after SAH. Evidence for the use of various prophylactic adjuvant therapies to prevent vasospasm, including magnesium, phosphodiesterase 3 inhibitors, and therapeutic hypothermia, is emerging. Intrathecal administration of vasodilators or fibrinolytics may have offered advantages over systemic drug administration in the treatment of vasospasm. Pulmonary and cardiac complications are common after SAH, and are associated with an increased risk of mortality.

SUMMARY

The postoperative ICU period after SAH is associated with a significant morbidity and mortality risk, and recent studies have greatly contributed to our understanding of how to optimally manage these patients.