Intracranial Pressure Increases During Rewarming Period After Mild Therapeutic Hypothermia in Postcardiac Arrest Patients

The compliance with TTM protocol may benefit outcomes in cardiac arrest survivors: A retrospective cohort study

BACKGROUND

Established protocols for implementing high-quality targeted temperature management (TTM) provide guidance concerning the cooling rate, duration of maintenance, and rewarming speed. However, whether compliant to TTM protocols results in improved survival and better neurological recovery has not been examined.

METHODS

A retrospective cohort study enrolled 1141 survivors of non-traumatic adult cardiac arrest with a pre-arrest cerebral performance category (CPC) score of 1-2 from 2015 to 2020 at a tertiary medical center. Of the survivors, 330 patients who underwent TTM were further included. Patients with spontaneous hypothermia (<35 °C) (n = 107) and expired during the TTM (n = 21) were excluded. A total of 202 patients were thus enrolled. One hundred and ten patients underwent TTM that completely complied with the protocol (protocol-complaint group), but 92 patients deviated in some manner from the protocol (protocol non-compliant group).

RESULTS

Fifty patients (50%) and 46 patients (50%) in the protocol-compliant and non-compliant groups, respectively, did not survive to hospital discharge. In the protocol-compliant group, 42 patients (38.2%) had favorable neurological recovery, compared with 32 patients (34.8%) in the protocol non-compliant group. After adjusting for age, initial shockable rhythm, witnessed collapse, and cardiopulmonary resuscitation duration, protocol non-compliant was associated with the poor neurological outcomes (aOR 2.44, 95% CI = 1.13-5.25), but not with in-hospital mortality (aOR 1.31, 95% CI = 0.70-2.47). The most common reason for noncompliance was a prolonged duration reaching the target temperature (n = 33, 58.7%). The number of phases of non-compliant was not significantly associated with in-hospital mortality or poor neurological recovery.

CONCLUSION

Among cardiac arrest survivors undergoing TTM, those who did not receive TTM that in compliance with the protocol were more likely to experience poor neurological recovery than those whose TTM fully complied with the protocols. The most frequently identified deviation was a prolonged duration to reaching the target temperature.

Emergent Management of Hypoxic-Ischemic Brain Injury

OBJECTIVE

This article outlines interventions used to improve outcomes for patients with hypoxic-ischemic brain injury after cardiac arrest.

LATEST DEVELOPMENTS

Emergent management of patients after cardiac arrest requires prevention and treatment of primary and secondary brain injury. Primary brain injury is minimized by excellent initial resuscitative efforts. Secondary brain injury prevention requires the detection and correction of many pathophysiologic processes that may develop in the hours to days after the initial arrest. Key physiologic parameters important to secondary brain injury prevention include optimization of mean arterial pressure, cerebral perfusion, oxygenation and ventilation, intracranial pressure, temperature, and cortical hyperexcitability. This article outlines recent data regarding the treatment and prevention of secondary brain injury. Different patients likely benefit from different treatment strategies, so an individualized approach to treatment and prevention of secondary brain injury is advisable. Clinicians must use multimodal sources of data to prognosticate outcomes after cardiac arrest while recognizing that all prognostic tools have shortcomings.

ESSENTIAL POINTS

Neurologists should be involved in the postarrest care of patients with hypoxic-ischemic brain injury to improve their outcomes. Postarrest care requires nuanced and patient-centered approaches to the prevention and treatment of primary and secondary brain injury and neuroprognostication.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement from the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

Critical Care Management of Patients After Cardiac Arrest: A Scientific Statement From the American Heart Association and Neurocritical Care Society

The critical care management of patients after cardiac arrest is burdened by a lack of high-quality clinical studies and the resultant lack of high-certainty evidence. This results in limited practice guideline recommendations, which may lead to uncertainty and variability in management. Critical care management is crucial in patients after cardiac arrest and affects outcome. Although guidelines address some relevant topics (including temperature control and neurological prognostication of comatose survivors, 2 topics for which there are more robust clinical studies), many important subject areas have limited or nonexistent clinical studies, leading to the absence of guidelines or low-certainty evidence. The American Heart Association Emergency Cardiovascular Care Committee and the Neurocritical Care Society collaborated to address this gap by organizing an expert consensus panel and conference. Twenty-four experienced practitioners (including physicians, nurses, pharmacists, and a respiratory therapist) from multiple medical specialties, levels, institutions, and countries made up the panel. Topics were identified and prioritized by the panel and arranged by organ system to facilitate discussion, debate, and consensus building. Statements related to postarrest management were generated, and 80% agreement was required to approve a statement. Voting was anonymous and web based. Topics addressed include neurological, cardiac, pulmonary, hematological, infectious, gastrointestinal, endocrine, and general critical care management. Areas of uncertainty, areas for which no consensus was reached, and future research directions are also included. Until high-quality studies that inform practice guidelines in these areas are available, the expert panel consensus statements that are provided can advise clinicians on the critical care management of patients after cardiac arrest.

Temperature control after cardiac arrest

Managing temperature is an important part of post-cardiac arrest care. Fever or hyperthermia during the first few days after cardiac arrest is associated with worse outcomes in many studies. Clinical data have not determined any target temperature or duration of temperature management that clearly improves patient outcomes. Current guidelines and recent reviews recommend controlling temperature to prevent hyperthermia. Higher temperatures can lead to secondary brain injury by increasing seizures, brain edema and metabolic demand. Some data suggest that targeting temperature below normal could benefit select patients where this pathology is common. Clinical temperature management should address the physiology of heat balance. Core temperature reflects the heat content of the head and torso, and changes in core temperature result from changes in the balance of heat production and heat loss. Clinical management of patients after cardiac arrest should include measurement of core temperature at accurate sites and monitoring signs of heat production including shivering. Multiple methods can increase or decrease heat loss, including external and internal devices. Heat loss can trigger compensatory reflexes that increase stress and metabolic demand. Therefore, any active temperature management should include specific pharmacotherapy or other interventions to control thermogenesis, especially shivering. More research is required to determine whether individualized temperature management can improve outcomes.

Cerebral monitoring in a pig model of cardiac arrest with 48 h of intensive care

Background

Neurological injury is the primary cause of death after out-of-hospital cardiac arrest. There is a lack of studies investigating cerebral injury beyond the immediate post-resuscitation phase in a controlled cardiac arrest experimental setting.

Methods

The aim of this study was to investigate temporal changes in measures of cerebral injury and metabolism in a cardiac arrest pig model with clinically relevant post-cardiac arrest intensive care. A cardiac arrest group (n = 11) underwent 7 min of no-flow and was compared with a sham group (n = 6). Pigs underwent intensive care with 24 h of hypothermia at 33 °C. Blood markers of cerebral injury, cerebral microdialysis, and intracranial pressure (ICP) were measured. After 48 h, pigs underwent a cerebral MRI scan. Data are presented as median [25th; 75th percentiles].

Results

Return of spontaneous circulation was achieved in 7/11 pigs. Time to ROSC was 4.4 min [4.2; 10.9]. Both NSE and NfL increased over time (p < 0.001), and were higher in the cardiac arrest group at 48 h (NSE 4.2 µg/L [2.4; 6.1] vs 0.9 [0.7; 0.9], p < 0.001; NfL 63 ng/L [35; 232] vs 29 [21; 34], p = 0.02). There was no difference in ICP at 48 h (17 mmHg [14; 24] vs 18 [13; 20], p = 0.44). The cerebral lactate/pyruvate ratio had secondary surges in 3/7 cardiac arrest pigs after successful resuscitation. Apparent diffusion coefficient was lower in the cardiac arrest group in white matter cortex (689 × 10^–6 mm²/s [524; 765] vs 800 [799; 815], p = 0.04) and hippocampus (854 [834; 910] vs 1049 [964; 1180], p = 0.03). N-Acetylaspartate was lower on MR spectroscopy in the cardiac arrest group (− 17.2 log [− 17.4; − 17.0] vs − 16.9 [− 16.9; − 16.9], p = 0.03).

Conclusions

We have developed a clinically relevant cardiac arrest pig model that displays cerebral injury as marked by NSE and NfL elevations, signs of cerebral oedema, and reduced neuron viability. Overall, the burden of elevated ICP was low in the cardiac arrest group. A subset of pigs undergoing cardiac arrest had persisting metabolic disturbances after successful resuscitation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-022-00475-2.

Therapeutic hypothermia for stroke: Unique challenges at the bedside

Therapeutic hypothermia has shown promise as a means to improving neurological outcomes at several neurological conditions. At the clinical level, it has been shown to improve outcomes in comatose survivors of cardiac arrest and in neonatal hypoxic ischemic encephalopathy, but has yet to be convincingly demonstrated in stroke. While numerous preclinical studies have shown benefit in stroke models, translating this to the clinical level has proven challenging. Major obstacles include cooling patients with typical stroke who are awake and breathing spontaneously but often have significant comorbidities. Solutions around these problems include selective brain cooling and cooling to lesser depths or avoiding hyperthermia. This review will cover the mechanisms of protection by therapeutic hypothermia, as well as recent progress made in selective brain cooling and the neuroprotective effects of only slightly lowering brain temperature. Therapeutic hypothermia for stroke has been shown to be feasible, but has yet to be definitively proven effective. There is clearly much work to be undertaken in this area.

Flufenamic acid improves survival and neurologic outcome after successful cardiopulmonary resuscitation in mice

Background

Brain injury is the main cause of high mortality and disability after successful cardiopulmonary resuscitation (CPR) from sudden cardiac arrest (CA). The transient receptor potential M4 (TRPM4) channel is a novel target for ameliorating blood–brain barrier (BBB) disruption and neuroinflammation. Herein, we tested whether flufenamic acid (FFA), which is reported to block TRPM4 with high potency, could confer neuroprotection against brain injury secondary to CA/CPR and whether its action was exerted by blocking the TRPM4 channel.

Methods

Wild-type (WT) and Trpm4 knockout (Trpm4^−/−) mice subjected to 10-min CA/CPR were randomized to receive FFA or vehicle once daily. Post-CA/CPR brain injuries including neurologic deficits, survival rate, histological damage, edema formation, BBB destabilization and neuroinflammation were assessed.

Results

In WT mice subjected to CA/CPR, FFA was effective in improving survival and neurologic outcome, reducing neuropathological injuries, attenuating brain edema, lessening the leakage of IgG and Evans blue dye, restoring tight junction protein expression and promoting microglia/macrophages from the pro-inflammatory subtype toward the anti-inflammatory subtype. In comparison to WT mice, Trpm4^−/− mice exhibited less neurologic deficiency, milder histological impairment, more BBB integrity and more anti-inflammatory microglia/macrophage polarization. As expected, FFA did not provide a benefit of superposition compared with vehicle in the Trpm4^−/− mice after CA/CPR.

Conclusions

FFA mitigates BBB breach and modifies the functional status of microglia/macrophages, thereby improving survival and neurologic deficits following CA/CPR. The neuroprotective effects occur at least partially by interfering with the TRPM4 channel in the neurovascular unit. These results indicate the significant clinical potential of FFA to improve the prognosis for CA victims who are successfully resuscitated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02571-2.

Intracranial Pressure Patterns and Neurological Outcomes in Out-of-Hospital Cardiac Arrest Survivors after Targeted Temperature Management: A Retrospective Observational Study

We aimed to investigate intracranial pressure (ICP) changes over time and the neurologic prognosis for out-of-hospital cardiac arrest (OHCA) survivors who received targeted temperature management (TTM). ICP was measured immediately after return of spontaneous circulation (ROSC) (day 1), then at 24 h (day 2), 48 h (day 3), and 72 h (day 4), through connecting a lumbar drain catheter to a manometer or a LiquoGuard machine. Neurological outcomes were determined at 3 months after ROSC, and a poor neurological outcome was defined as Cerebral Performance Category 3–5. Of the 91 patients in this study (males, n = 67, 74%), 51 (56%) had poor neurological outcomes. ICP was significantly higher in the poor outcome group at each time point except day 4. ICP elevation was highest between days 2 and 3 in the good outcome group, and between days 1 and 2 in the poor outcome group. However, there was no difference in total ICP elevation between the poor and good outcome groups (3.0 vs. 3.1; p = 0.476). All OHCA survivors who had received TTM had elevated ICP, regardless of neurologic prognosis. However, the changing pattern of ICP levels differed depending on the neurological outcome.

Hypertonic versus isotonic crystalloid infusion for cerebral perfusion pressure in a porcine experimental cardiac arrest model

BACKGROUND

The effect of intravenous (IV) fluid administration type on cerebral perfusion pressure (CePP) during cardiopulmonary resuscitation (CPR) is controversial. The purpose of this study was to evaluate the association between IV fluid type and CePP in a porcine cardiac arrest model.

METHODS

We randomly assigned 12 pigs to the hypertonic crystalloid, isotonic crystalloid and no-fluid groups. After 4 min of untreated ventricular fibrillation (VF), chest compression was conducted for 2 cycles (CC only). Chest compression with IV fluid infusion (CC + IV) was followed for 2 cycles. Advanced life support, including defibrillation and epinephrine, was added for 8 cycles (ALS phase). Mean arterial pressure (MAP), intracranial pressure (ICP) and CePP were measured. A paired t-test was used to measure the mean difference in CePP.

RESULTS

Twelve pigs underwent the experiment. The hypertonic crystalloid group showed higher CePP values than those demonstrated by the isotonic crystalloid group from ALS cycles 2 to 8. The MAP values in the hypertonic group were higher than those in the isotonic group starting at ALS cycle 2. The ICP values in the hypertonic group were lower than those in the isotonic group starting at ALS cycle 4. From ALS cycles 2 to 8, the reduction in the mean difference in the isotonic group was larger than that in the other groups.

CONCLUSION

In a VF cardiac arrest porcine study, the hypertonic crystalloid group showed higher CePP values by maintaining higher MAP values and lower ICP values than those of the isotonic crystalloid group.

Different Stratification of Physiological Factors Affecting Cerebral Perfusion Pressure in Hypoxic-Ischemic Brain Injury after Cardiac Arrest According to Visible or Non-Visible Primary Brain Injury: A Retrospective Observational Study

We aimed to explore the stratification of physiological factors affecting cerebral perfusion pressure, including arterial oxygen tension, arterial carbon dioxide tension, mean arterial pressure, intracranial pressure (ICP), and blood-brain barrier (BBB) status, with respect to primary or secondary brain injury (PBI or SBI) after out-of-hospital cardiac arrest (OHCA). Among the retrospectively enrolled 97 comatose OHCA survivors undergoing post-cardiac arrest (PCA) care, 46 (47.4%) with already established PBI (high signal intensity (HSI) on diffusion-weighted imaging (DWI) had higher ICP (p = 0.02) and poorer BBB status (p < 0.01) than the non-HSI group. On subgroup analysis within the non-HSI group to exclude the confounding effect of already established PBI, 40 (78.4%) patients with good neurological outcomes had lower ICP at 24 h (11.0 vs. 16.0 mmHg, p < 0.01) and more stable BBB status (p = 0.17 in pairwise comparison) compared to those with poor neurological outcomes, despite the non-significant differences in other physiological factors. OHCA survivors with HSI on DWI showed significantly higher ICP and poorer BBB status at baseline before PCA care than those without HSI. Despite the negative DWI findings before PCA care, OHCA survivors have a cerebral penumbra at risk for potentially leading the poor neurological outcome from unsuppressed SBI, which may be associated with increased ICP and BBB permeability.

Elevated jugular venous oxygen saturation after cardiac arrest

BACKGROUND

We performed a retrospective analysis of our earlier study on cerebral oxygenation monitoring by jugular venous oximetry (SjvO₂) in patients of out-of-hospital cardiac arrest (OHCA). The study was focused on high SjvO₂ values (≥75%) and their association with neurological outcomes and serum neuron-specific enolase (NSE) concentration.

METHOD

Forty OHCA patients were divided into (i) high (Group I), (ii) normal (Group II), and (iii) low (Group III) SjvO₂, with the mean SjvO₂ ≥ 75%, 55-74% and <55% respectively. The neurological outcome was evaluated using the Cerebral Performance Category scale (CPC) on the 90th day after cardiac arrest (post-CA). NSE concentration was determined after ICU admission and then at 24, 48, and 72 hours (h) post-CA.

RESULTS

High mean SjvO₂ occurred in 67% of patients, while no patients had low mean SjvO₂. The unfavourable outcome was significantly more common in Group I than Group II (74% versus 23%, p < 0.01). Group I patients had significantly higher median NSE than Group II at 48 and 72 h post-CA. A positive correlation was found between SjvO₂ and PaCO₂. Each 1 kPa increase in CO₂ led to an increase of SjvO₂ by 2.2 %+/-0.66 (p < 0.01) in group I and by 5.7%+/-1.36 (p < 0.0001) in group II. There was no correlation between SjvO₂ and MAP or SjvO₂ and PaO₂.

CONCLUSION

High mean SjvO₂ are often associated with unfavourable outcomes and high NSE at 48 and 72 hours post-CA. Not only low but also high SjvO₂ values may require therapeutic intervention.

Goal-Directed Care Using Invasive Neuromonitoring Versus Standard of Care After Cardiac Arrest: A Matched Cohort Study

PURPOSE

Following return of spontaneous circulation after cardiac arrest, hypoxic ischemic brain injury is the primary cause of mortality and disability. Goal-directed care using invasive multimodal neuromonitoring has emerged as a possible resuscitation strategy. We evaluated whether goal-directed care was associated with improved neurologic outcome in hypoxic ischemic brain injury patients after cardiac arrest.

DESIGN

Retrospective, single-center, matched observational cohort study.

SETTING

Quaternary academic medical center.

PATIENTS

Adult patients admitted to the ICU following return of spontaneous circulation postcardiac arrest with clinical evidence of hypoxic ischemic brain injury defined as greater than or equal to 10 minutes of cardiac arrest with an unconfounded postresuscitation Glasgow Coma Scale of less than or equal to 8.

INTERVENTIONS

We compared patients who underwent goal-directed care using invasive neuromonitoring with those treated with standard of care (using both total and matched groups).

MEASUREMENTS AND MAIN RESULTS

Goal-directed care patients were matched 1:1 to standard of care patients using propensity scores and exact matching. The primary outcome was a 6-month favorable neurologic outcome (Cerebral Performance Category of 1 or 2). We included 65 patients, of whom 21 received goal-directed care and 44 patients received standard of care. The median age was 50 (interquartile range, 35-61), 48 (74%) were male, and seven (11%) had shockable rhythms. Favorable neurologic outcome at 6 months was significantly greater in the goal-directed care group (n = 9/21 [43%]) compared with the matched (n = 2/21 [10%], p = 0.016) and total (n = 8/44 [18%], p = 0.034) standard of care groups. Goal-directed care group patients had higher mean arterial pressure (p < 0.001 vs total; p = 0.0060 vs matched) and lower temperature (p = 0.007 vs total; p = 0.041 vs matched).

CONCLUSIONS

In this preliminary study of patients with hypoxic ischemic brain injury postcardiac arrest, goal-directed care guided by invasive neuromonitoring was associated with a 6-month favorable neurologic outcome (Cerebral Performance Category 1 or 2) versus standard of care. Significant work is required to confirm this finding in a prospectively designed study.

Post-cardiac arrest care and targeted temperature management: A consensus of scientific statement from the Taiwan Society of Emergency & Critical Care Medicine, Taiwan Society of Critical Care Medicine and Taiwan Society of Emergency Medicine

BACKGROUND

Post-cardiac arrest care is critically important in bringing cardiac arrest patients to functional recovery after the detrimental event. More high quality studies are published and evidence is accumulated for the post-cardiac arrest care in the recent years. It is still a challenge for the clinicians to integrate these scientific data into the real clinical practice for such a complicated intensive care involving many different disciplines.

METHODS

With the cooperation of the experienced experts from all disciplines relevant to post-cardiac arrest care, the consensus of the scientific statement was generated and supported by three major scientific groups for emergency and critical care in post-cardiac arrest care.

RESULTS

High quality post-cardiac arrest care, including targeted temperature management, early evaluation of possible acute coronary event and intensive care for hemodynamic and respiratory care are inevitably needed to get full recovery for cardiac arrest. Management of these critical issues were reviewed and proposed in the consensus CONCLUSION: The goal of the statement is to provide help for the clinical physician to achieve better quality and evidence-based care in post-cardiac arrest period.

Cerebral Edema After Cardiopulmonary Resuscitation: A Therapeutic Target Following Cardiac Arrest?

We sought to review the role that cerebral edema plays in neurologic outcome following cardiac arrest, to understand whether cerebral edema might be an appropriate therapeutic target for neuroprotection in patients who survive cardiopulmonary resuscitation. Articles indexed in PubMed and written in English. Following cardiac arrest, cerebral edema is a cardinal feature of brain injury and is a powerful prognosticator of neurologic outcome. Like other conditions characterized by cerebral ischemia/reperfusion, neuroprotection after cardiac arrest has proven to be difficult to achieve. Neuroprotection after cardiac arrest generally has focused on protecting neurons, not the microvascular endothelium or blood-brain barrier. Limited preclinical data suggest that strategies to reduce cerebral edema may improve neurologic outcome. Ongoing research will be necessary to determine whether targeting cerebral edema will improve patient outcomes after cardiac arrest.

Systemic Inflammatory Response Syndrome (SIRS) Score Independently Predicts Poor Outcome in Isolated Traumatic Brain Injury

INTRODUCTION

Systemic inflammatory response syndrome (SIRS) is frequently observed after various types of acute cerebral injury and has been linked to clinical deterioration in non-traumatic brain injury (TBI). SIRS scores have also been shown to be predictive of length of stay and mortality in trauma patients. We aimed to determine the prognostic utility of SIRS present at admission in trauma patients with isolated TBI.

METHODS

This was a 5-year retrospective cohort study of adults (≥18 years) with isolated TBI admitted to a Level II trauma center. The prognostic value of SIRS, total SIRS scores, and each SIRS criterion was examined by Χ ² and logistic regression analyses.

RESULTS

Of the 330 patients identified, 50 (15.2%) met SIRS criteria. SIRS was significantly associated with poor outcome (P < 0.001). Relative risk of poor outcome was 2.7 times higher in patients with a SIRS score of 2 on admission (P = 0.007) and increased significantly to 6.5 times in patients with a SIRS score of 3 (P = 0.002). Logistic regression demonstrated SIRS and each criterion to be significant independent prognostic factors (SIRS, P = 0.030; body temperature, P = 0.006; tachypnea, P = 0.022, tachycardia P = 0.023).

CONCLUSION

SIRS at admission is an independent predictor of poor outcome in isolated TBI patients. These data demonstrate SIRS to be an important clinical tool that may be used in facilitating prognostication, particularly in elderly trauma patients. Future prospective studies aimed at therapeutic interventions to mitigate SIRS in TBI patients are warranted.

LEVEL OF EVIDENCE

Prognostic, Level III.

Usefulness of Intracranial Pressure and Mean Arterial Pressure for Predicting Neurological Prognosis in Cardiac Arrest Survivors Who Undergo Target Temperature Management

We aimed to compare the relationship of mean arterial pressure (MAP) and intracranial pressure (ICP) to predict the neurological prognosis in cardiac arrest (CA) survivors. We retrospectively examined out-of-hospital CA patients treated with targeted temperature management. ICP was measured using cerebrospinal fluid (CSF) pressure, whereas MAP was measured as blood pressure monitored through the radial or femoral artery during CSF pressure measurement. Primary outcome was 6-month neurological outcome. Of 92 enrolled patients, the favorable outcome group comprised 31 (34%) patients. The median and interquartile range of MAP were significantly higher and ICP was significantly lower in patients with favorable neurological outcomes than in those with unfavorable neurological outcomes (94.3 mmHg [80.0-105.3] vs. 82.0 mmHg [65.3-96.3], p = 0.021 and 9.4 mmHg [10.8-8.7] vs. 18.8 mmHg [20.0-15.7], p < 0.001, respectively). ICP showed the higher area under the receiver operating characteristic curve (area under curve [AUC] = 0.953, 95% confidence interval [CI] = 0.888-0.986) for neurological outcome prediction. MAP showed the lower AUC (0.648, 95% CI = 0.541-0.744). Higher accurate prognosis was predicted by ICP than MAP, and the prognostic performance was good. Prospective multicenter studies are required to confirm these results.

Intracranial pressure and compliance in hypoxic ischemic brain injury patients after cardiac arrest

INTRODUCTION

In hypoxic ischemic brain injury (HIBI), increased intracranial pressure (ICP) can ensue from cerebral edema stemming from cytotoxic and vasogenic mechanisms. Downstream sequelae of restricted cerebral blood flow lead to neurologic braindeath. There is limited data characterizing the temporal trends and patterns of ICP and compliance in human HIBI patients.

METHODS

Patients underwent invasive ICP monitoring with a parenchymal probe (Camino) and were managed with a tier-based management algorithm for elevated ICP. Data pertaining to mean arterial pressure (MAP), ICP, brain tissue oxygenation (PbtO₂), end tidal carbon dioxide (ETCO₂), core body temperature and RAP (moving correlation coefficient between mean ICP and its mean pulse amplitude) as a measure of intracranial compliance were recorded in the ICM + software. Data pertaining to ICP lowering interventions was also collected.

RESULTS

Ten patients were included with a median age of 47 (range 20-71) and seven were male (7/10). The mean ICP was 14 mmHg (SD 11) and time of ICP> 20 mmHg was 22% (range 0-100). The mean MAP, ETCO₂ and temperature were 89 mmHg (SD 13), 31 mmHg (SD 7), 35.7 °C (SD 0.9), respectively. The mean RAP was 0.58 (SD 0.34) and time of RAP > 0.4 was 78% (range 57-97). There were no significant relationships between ETCO₂ and temperature with ICP.

CONCLUSIONS

In our cohort, HIBI was characterized by normal ICP but with limited intracranial compliance. However, significant in between patient heterogeneity exists with respect to temporal patterns of intracranial pressure - volume relationships in HIBI.

TRIAL REGISTRATION

clinicaltrials.gov (NCT03609333).

Pilot study on a rewarming rate of 0.15°C/hr versus 0.25°C/hr and outcomes in post cardiac arrest patients

Objective

Cerebral hemodynamic and metabolic changes may occur during the rewarming phase of targeted temperature management in post cardiac arrest patients. Yet, studies on different rewarming rates and patient outcomes are limited. This study aimed to investigate post cardiac arrest patients who were rewarmed with different rewarming rates after 24 hours of hypothermia and the association of these rates to the neurologic outcomes.

Methods

This study retrospectively investigated post cardiac arrest patients treated with targeted temperature management and rewarmed with rewarming rates of 0.15°C/hr and 0.25°C/hr. The association of the rewarming rate with poor neurologic outcomes (cerebral performance category score, 3 to 5) was investigated.

Results

A total of 71 patients were analyzed (0.15°C/hr, n=36; 0.25°C/hr, n=35). In the comparison between 0.15°C/hr and 0.25°C/hr, the poor neurologic outcome did not significantly differ (24 [66.7%] vs. 25 [71.4%], respectively; P=0.66). In the multivariate analysis, the rewarming rate of 0.15°C/hr was not associated with the 1-month neurologic outcome improvement (odds ratio, 0.54; 95% confidence interval, 0.16 to 1.69; P=0.28).

Conclusion

The rewarming rates of 0.15°C/hr and 0.25°C/hr were not associated with the neurologic outcome difference in post cardiac arrest patients.

A comparison of non-invasive versus invasive measures of intracranial pressure in hypoxic ischaemic brain injury after cardiac arrest

AIM

Increased intracranial pressure (ICP) in hypoxic ischaemic brain injury (HIBI) can cause secondary ischaemic brain injury and culminate in brain death. Invasive ICP monitoring is limited by associated risks in HIBI patients. We sought to evaluate the agreement between invasive ICP measurements and non-invasive estimators of ICP (nICP) in HIBI patients.

METHODS

Eligible consecutive adult (age>18) cardiac arrest patients with HIBI were included as part of a single centre prospective interventional study. Invasive ICP monitoring and nICP measurements were undertaken using: a) transcranial Doppler ultrasonography (TCD), b) optic nerve sheet diameter ultrasound (ONSD) and c) jugular venous bulb pressure (JVP). Multiple measurements applied in linear mixed-effects models were considered to obtain the correlation coefficient between ICP and nICP as well as their predictive abilities to detect intracranial hypertension (ICP≥20mm Hg).

RESULTS

Eleven patients were included (median age of 47 [range 20-71], 8 males and 3 females). There was a linear relationship between ICP and nICP with ONSD (R=0.53 [p<0.0001]), JVP (R=0.38 [p<0.001]) and TCD (R=0.30 [p<0.01]). The ability to predict intracranial hypertension was highest for ONSD and TCD (area under the receiver operating curve (AUC)=0.96 [95% CI: 0.90-1.00] and AUC=0.91 [95% CI: 0.83-1.00], respectively). JVP presented the weakest prediction ability (AUC=0.75 [95% CI: 0.56-0.94]).

CONCLUSIONS

ONSD and TCD methods demonstrated agreement with invasively-monitored ICP, suggesting their potential roles in the detection of intracranial hypertension in HIBI after cardiac arrest.

Targeted Temperature Management and Multimodality Monitoring of Comatose Patients After Cardiac Arrest

Out-of-hospital cardiac arrest (CA) remains a leading cause of sudden morbidity and mortality; however, outcomes have continued to improve in the era of targeted temperature management (TTM). In this review, we highlight the clinical use of TTM, and provide an updated summary of multimodality monitoring possible in a modern ICU. TTM is neuroprotective for survivors of CA by inhibiting multiple pathophysiologic processes caused by anoxic brain injury, with a final common pathway of neuronal death. Current guidelines recommend the use of TTM for out-of-hospital CA survivors who present with a shockable rhythm. Further studies are being completed to determine the optimal timing, depth and duration of hypothermia to optimize patient outcomes. Although a multidisciplinary approach is necessary in the CA population, neurologists and neurointensivists are central in selecting TTM candidates and guiding patient care and prognostic evaluation. Established prognostic tools include clinal exam, SSEP, EEG and MR imaging, while functional MRI and invasive monitoring is not validated to improve outcomes in CA or aid in prognosis. We recommend that an evidence-based TTM and prognostication algorithm be locally implemented, based on each institution's resources and limitations. Given the high incidence of CA and difficulty in predicting outcomes, further study is urgently needed to determine the utility of more recent multimodality devices and studies.

Middle cerebral artery flow, the critical closing pressure, and the optimal mean arterial pressure in comatose cardiac arrest survivors-An observational study

AIM

This study estimated the critical closing pressure (CrCP) of the cerebrovascular circulation during the post-cardiac arrest syndrome and determined if CrCP differs between survivors and non-survivors. We also compared patients after cardiac arrest to normal controls.

METHODS

A prospective observational study was performed at the ICU of a tertiary university hospital in Nijmegen, the Netherlands. We studied 11 comatose patients successfully resuscitated from a cardiac arrest and treated with mild therapeutic hypothermia and 10 normal control subjects. Mean flow velocity (MFV) in the middle cerebral artery was measured by transcranial Doppler at several time points after admission to the ICU. CrCP was determined by a cerebrovascular impedance model.

RESULTS

MFV was similar in survivors and non-survivors upon admission to the ICU, but increased stronger in non-survivors compared to survivors throughout the observation period (P<0.001). MFV was significantly lower in survivors immediately after cardiac arrest compared to normal controls (P<0.001), with a gradual restoration toward normal values. CrCP decreased significantly from 61.4[51.0-77.1]mmHg to 41.7[39.9-51.0]mmHg in the first 48h, after which it remained stable (P<0.001). CrCP was significantly higher in survivors compared to non-survivors (P=0.002). CrCP immediately after cardiac arrest was significantly higher compared to the control group (P=0.02).

CONCLUSIONS

CrCP is high after cardiac arrest with high cerebrovascular resistance and low MFV. This suggests that cerebral perfusion pressure should be maintained at a sufficient high level to avoid secondary brain injury. Failure to normalize the cerebrovascular profile may be a parameter of poor outcome.