Cerebral perfusion and metabolism with mean arterial pressure 90 vs. 60 mmHg in a porcine post cardiac arrest model with and without targeted temperature management

The association between initial post-resuscitation diastolic blood pressure and survival after pediatric cardiac arrest: a retrospective study

BACKGROUND

Limited research has analyzed the association between diastolic blood pressure (DBP) and survival after pediatric cardiopulmonary resuscitation (CPR). This study aimed to explore the association between post-resuscitation diastolic blood pressure and survival in pediatric patients who underwent CPR.

METHOD

This retrospective single-center study included pediatric patients admitted to the pediatric intensive care unit of Asan Medical Center between January 2016 to November 2022. Patients undergoing extracorporeal CPR and those with unavailable data were excluded. The primary endpoint was survival to ICU discharge.

RESULTS

A total of 106 patients were included, with 67 (63.2%) achieving survival to ICU discharge. Multivariate logistic regression analysis identified DBP within 1 h after ROSC as the sole significant variable (p = 0.002, aOR, 1.043; 95% CI, 1.016-1.070). Additionally, DBP within 1 h demonstrated an area under the ROC curve of 0.7 (0.592-0.809) for survival to ICU discharge, along with mean blood pressure within the same timeframe.

CONCLUSION

Our study highlights the importance of DBP within 1-hour post-ROSC as a significant prognostic factor for survival to ICU discharge. However, further validation through further prospective large-scale studies is warranted to confirm the appropriate post-resuscitation DBP of pediatric patients.

Cerebral perfusion and metabolism with mild hypercapnia vs. normocapnia in a porcine post cardiac arrest model with and without targeted temperature management

Aim

To determine whether targeting mild hypercapnia (PaCO2 7 kPa) would yield improved cerebral blood flow and metabolism compared to normocapnia (PaCO2 5 kPa) with and without targeted temperature management to 33 °C (TTM33) in a porcine post-cardiac arrest model.

Methods

39 pigs were resuscitated after 10 minutes of cardiac arrest using cardiopulmonary bypass and randomised to TTM33 or no-TTM, and hypercapnia or normocapnia. TTM33 was managed with intravasal cooling. Animals were stabilized for 30 minutes followed by a two-hour intervention period. Hemodynamic parameters were measured continuously, and neuromonitoring included intracranial pressure (ICP), pressure reactivity index, cerebral blood flow, brain-tissue pCO2 and microdialysis. Measurements are reported as proportion of baseline, and areas under the curve during the 120 min intervention period were compared.

Results

Hypercapnia increased cerebral flow in both TTM33 and no-TTM groups, but also increased ICP (199% vs. 183% of baseline, p = 0.018) and reduced cerebral perfusion pressure (70% vs. 84% of baseline, p < 0.001) in no-TTM animals. Cerebral lactate (196% vs. 297% of baseline, p < 0.001), pyruvate (118% vs. 152% of baseline, p < 0.001), glycerol and lactate/pyruvate ratios were lower with hypercapnia in the TTM33 group, but only pyruvate (133% vs. 150% of baseline, p = 0.002) was lower with hypercapnia among no-TTM animals.

Conclusion

In this porcine post-arrest model, hypercapnia led to increased cerebral flow both with and without hypothermia, but also increased ICP and reduced cerebral perfusion pressure in no-TTM animals. The effects of hypercapnia were different with and without TTM.(Institutional protocol number: FOTS, id 14931).

Feasibility of Magnetic Resonance-Based Conductivity Imaging as a Tool to Estimate the Severity of Hypoxic-Ischemic Brain Injury in the First Hours After Cardiac Arrest

BACKGROUND

Early identification of the severity of hypoxic-ischemic brain injury (HIBI) after cardiac arrest can be used to help plan appropriate subsequent therapy. We evaluated whether conductivity of cerebral tissue measured using magnetic resonance-based conductivity imaging (MRCI), which provides contrast derived from the concentration and mobility of ions within the imaged tissue, can reflect the severity of HIBI in the early hours after cardiac arrest.

METHODS

Fourteen minipigs were resuscitated after 5 min or 12 min of untreated cardiac arrest. MRCI was performed at baseline and at 1 h and 3.5 h after return of spontaneous circulation (ROSC).

RESULTS

In both groups, the conductivity of cerebral tissue significantly increased at 1 h after ROSC compared with that at baseline (P = 0.031 and 0.016 in the 5-min and 12-min groups, respectively). The increase was greater in the 12-min group, resulting in significantly higher conductivity values in the 12-min group (P = 0.030). At 3.5 h after ROSC, the conductivity of cerebral tissue in the 12-min group remained increased (P = 0.022), whereas that in the 5-min group returned to its baseline level.

CONCLUSIONS

The conductivity of cerebral tissue was increased in the first hours after ROSC, and the increase was more prominent and lasted longer in the 12-min group than in the 5-min group. Our findings suggest the promising potential of MRCI as a tool to estimate the severity of HIBI in the early hours after cardiac arrest.

A nomogram for predicting sepsis-associated delirium: a retrospective study in MIMIC III

OBJECTIVE

To develop a nomogram for predicting the occurrence of sepsis-associated delirium (SAD).

MATERIALS AND METHODS

Data from a total of 642 patients were retrieved from the Medical Information Mart for Intensive Care (MIMIC III) database to build a prediction model. Multivariate logistic regression was performed to identify independent predictors and establish a nomogram to predict the occurrence of SAD. The performance of the nomogram was assessed in terms of discrimination and calibration by bootstrapping with 1000 resamples.

RESULTS

Multivariate logistic regression identified 4 independent predictors for patients with SAD, including Sepsis-related Organ Failure Assessment(SOFA) (p = 0.004; OR: 1.131; 95% CI 1.040 to 1.231), mechanical ventilation (P < 0.001; OR: 3.710; 95% CI 2.452 to 5.676), phosphate (P = 0.047; OR: 1.165; 95% CI 1.003 to 1.358), and lactate (P = 0.023; OR: 1.135; 95% CI 1.021 to 1.270) within 24 h of intensive care unit (ICU) admission. The area under the curve (AUC) of the predictive model was 0.742 in the training set and 0.713 in the validation set. The Hosmer - Lemeshow test showed that the model was a good fit (p = 0.471). The calibration curve of the predictive model was close to the ideal curve in both the training and validation sets. The DCA curve also showed that the predictive nomogram was clinically useful.

CONCLUSION

We constructed a nomogram for the personalized prediction of delirium in sepsis patients, which had satisfactory performance and clinical utility and thus could help clinicians identify patients with SAD in a timely manner, perform early intervention, and improve their neurological outcomes.

A randomized, double-blind trial comparing the effect of two blood pressure targets on global brain metabolism after out-of-hospital cardiac arrest

PURPOSE

This study aimed to assess the effect of different blood pressure levels on global cerebral metabolism in comatose patients resuscitated from out-of-hospital cardiac arrest (OHCA).

METHODS

In a double-blinded trial, we randomly assigned 60 comatose patients following OHCA to low (63 mmHg) or high (77 mmHg) mean arterial blood pressure (MAP). The trial was a sub-study in the Blood Pressure and Oxygenation Targets after Out-of-Hospital Cardiac Arrest-trial (BOX). Global cerebral metabolism utilizing jugular bulb microdialysis (JBM) and cerebral oxygenation (rSO₂) was monitored continuously for 96 h. The lactate-to-pyruvate (LP) ratio is a marker of cellular redox status and increases during deficient oxygen delivery (ischemia, hypoxia) and mitochondrial dysfunction. The primary outcome was to compare time-averaged means of cerebral energy metabolites between MAP groups during post-resuscitation care. Secondary outcomes included metabolic patterns of cerebral ischemia, rSO₂, plasma neuron-specific enolase level at 48 h and neurological outcome at hospital discharge (cerebral performance category).

RESULTS

We found a clear separation in MAP between the groups (15 mmHg, p < 0.001). Cerebral biochemical variables were not significantly different between MAP groups (LPR low MAP 19 (16-31) vs. high MAP 23 (16-33), p = 0.64). However, the LP ratio remained high (> 16) in both groups during the first 30 h. During the first 24 h, cerebral lactate > 2.5 mM, pyruvate levels > 110 µM, LP ratio > 30, and glycerol > 260 µM were highly predictive for poor neurological outcome and death with AUC 0.80. The median (IQR) rSO₂ during the first 48 h was 69.5% (62.0-75.0%) in the low MAP group and 69.0% (61.3-75.5%) in the high MAP group, p = 0.16.

CONCLUSIONS

Among comatose patients resuscitated from OHCA, targeting a higher MAP 180 min after ROSC did not significantly improve cerebral energy metabolism within 96 h of post-resuscitation care. Patients with a poor clinical outcome exhibited significantly worse biochemical patterns, probably illustrating that insufficient tissue oxygenation and recirculation during the initial hours after ROSC were essential factors determining neurological outcome.

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.

Association between blood pressure variability and clinical outcomes after successful recanalization in patients with large vessel occlusion stroke after mechanical thrombectomy

Objective

Nearly half of patients who undergo mechanical thrombectomy (MT) do not experience a favorable outcome. The association between blood pressure fluctuation and clinical outcomes after successful MT is controversial. We evaluated the influence of blood pressure variability (BPV) on the clinical outcomes of stroke patients with large vessel occlusion (LVO) who underwent successful recanalization after MT.

Methods

Patients with anterior circulation LVO stroke who underwent successful emergency MT (modified Thrombolysis in Cerebral Infarction, mTICI ≥ 2b) at the Shanghai Tenth People's Hospital of Tongji University from 2017 to 2021 were enrolled. Multivariate logistic models were used to investigate the association between BPV (mean arterial pressure [MAP] assessed using the standard deviation [SD]) and clinical outcomes. The primary outcome was 90-day modified Rankin Scale scores (mRS), and the secondary outcomes were 30-day mortality and symptomatic intracranial hemorrhage (sICH).

Results

A total of 458 patients (56.8% men), with a mean age of 72 ± 1 years, were enrolled. Among them, 207 (45.2%) patients had unfavorable functional outcomes (mRS score 3–6) at 90 days, 61 (13.3%) patients died within 30 days, and 20 (4.4%) patients had sICH. In a fully adjusted model, BPV was associated with a higher risk of a 90-day mRS score of 3–6 (P = 0.04), 30-day mortality (P < 0.01), and sICH (P < 0.01). A significant interaction between MAP SD and rescue futile recanalization treatment was observed (P < 0.01).

Conclusions

Among patients with LVO stroke who underwent successful recanalization, higher BPV was associated with worse functional outcomes, especially in those who underwent rescue treatment.

Bedside interpretation of cerebral energy metabolism utilizing microdialysis in neurosurgical and general intensive care

The microdialysis technique was initially developed for monitoring neurotransmitters in animals. In 1995 the technique was adopted to clinical use and bedside enzymatic analysis of glucose, pyruvate, lactate, glutamate and glycerol. Under clinical conditions microdialysis has also been used for studying cytokines, protein biomarkers, multiplex proteomic and metabolomic analyses as well as for pharmacokinetic studies and evaluation of blood-brain barrier function. This review focuses on the variables directly related to cerebral energy metabolism and the possibilities and limitations of microdialysis during routine neurosurgical and general intensive care. Our knowledge of cerebral energy metabolism is to a large extent based on animal experiments performed more than 40 years ago. However, the different biochemical information obtained from various techniques should be recognized. The basic animal studies analyzed brain tissue homogenates while the microdialysis technique reflects the variables in a narrow zone of interstitial fluid surrounding the probe. Besides the difference of the volume investigated, the levels of the biochemical variables differ in different compartments. During bedside microdialysis cerebral energy metabolism is primarily reflected in measured levels of glucose, lactate and pyruvate and the lactate to pyruvate (LP) ratio. The LP ratio reflects cytoplasmatic redox-state which increases instantaneously during insufficient aerobic energy metabolism. Cerebral ischemia is characterized by a marked increase in intracerebral LP ratio at simultaneous decreases in intracerebral levels of pyruvate and glucose. Mitochondrial dysfunction is characterized by a moderate increase in LP ratio at a very marked increase in cerebral lactate and normal or elevated levels of pyruvate and glucose. The patterns are of importance in particular for interpretations in transient cerebral ischemia. A new technique for evaluating global cerebral energy metabolism by microdialysis of the draining cerebral venous blood is discussed. In experimental studies it has been shown that pronounced global cerebral ischemia is reflected in venous cerebral blood. Jugular bulb microdialysis has been investigated in patients suffering from subarachnoid hemorrhage, during cardiopulmonary bypass and resuscitation after out of hospital cardiac arrest. Preliminary results indicate that the new technique may give valuable information of cerebral energy metabolism in clinical conditions when insertion of an intracerebral catheter is contraindicated.

Post-resuscitation diastolic blood pressure is a prognostic factor for outcomes of cardiac arrest patients: a multicenter retrospective registry-based analysis

Background

Post-resuscitation hemodynamic level is associated with outcomes. This study was conducted to investigate if post-resuscitation diastolic blood pressure (DBP) is a favorable prognostic factor.

Methods

Using TaIwan Network of Targeted Temperature ManagEment for CARDiac Arrest (TIMECARD) registry, we recruited adult patients who received targeted temperature management in nine medical centers between January 2014 and September 2019. After excluding patients with extracorporeal circulation support, 448 patients were analyzed. The first measured, single-point blood pressure after resuscitation was used for analysis. Study endpoints were survival to discharge and discharge with favorable neurologic outcomes (CPC 1–2). Multivariate analysis, area under the receiver operating characteristic curve (AUC), and generalized additive model (GAM) were used for analysis.

Results

Among the 448 patients, 182 (40.7%) patients survived, and 89 (19.9%) patients had CPC 1–2. In the multivariate analysis, DBP > 70 mmHg was an independent factor for survival (adjusted odds ratio [aOR] 2.16, 95% confidence interval [CI, 1.41–3.31]) and > 80 mmHg was an independent factor for CPC 1–2 (aOR 2.04, 95% CI [1.14–3.66]). GAM confirmed that DBP > 80 mmHg was associated with a higher likelihood of CPC 1–2. In the exploratory analysis, patients with DBP > 80 mmHg had a significantly higher prevalence of cardiogenic cardiac arrest (p = 0.015) and initial shockable rhythm (p = 0.045).

Conclusion

We found that DBP after resuscitation can predict outcomes, as a higher DBP level correlated with cardiogenic cardiac arrest.

Hemodynamic evaluation by serial right heart catheterizations after cardiac arrest; protocol of a sub-study from the Blood Pressure and Oxygenation Targets after Out-of-Hospital Cardiac Arrest-trial (BOX)

BACKGROUND

Neurological injury and mortality remain high in comatose patients resuscitated from out-of-hospital cardiac arrest (OHCA). Hypotension and hypoxia during post-resuscitation care have been associated with poor outcome, but the optimal oxygenation- and blood pressure-targets are unknown. The impact of different doses of norepinephrine on advanced hemodynamic after OHCA and the impact of different oxygenation-targets on pulmonary circulation and resistance (PVR), are unknown. The aims of this substudy of the "Blood pressure and oxygenations targets after out-of-hospital cardiac arrest (BOX)"-trial are to investigate the effect of two different MAP- and oxygenation-targets on advanced systemic and pulmonary hemodynamics measured by pulmonary artery catheters (PAC).

METHODS

The BOX-trial is an investigator-initiated, randomized, controlled study comparing targeted MAP of 63 mmHg vs 77 mmHg (double-blinded intervention) and 9-10 kPa versus PaO2 of 13-14 kPa oxygenation-targets (open-label). Per protocol, all patients will be monitored systematically with PACs. The primary endpoint of the hemodynamic-substudy is cardiac output for the MAP-intervention, and PVR for the oxygenation-intervention. For both endpoints, the difference within 48 h between groups are assessed. Secondary endpoints are pulmonary capillary wedge pressure and pulmonary arterial pressure and association between advanced hemodynamic variables and mortality and biomarkers of inflammation and brain injury.

DISCUSSION

In the BOX-trial, patients will be randomly allocated to two levels of MAP and oxygenation, which are central parts of post-resuscitation care and where evidence is sparse. The advanced-hemodynamic substudy will give valuable knowledge of the hemodynamic consequences of changing blood pressure and oxygen-levels of the critical cardiac patient. It will be one of the largest clinical, prospective trials of advanced hemodynamics measured by serial PACs in consecutive comatose patients, resuscitated after OHCA. The randomized and placebo-controlled trialdesign of the MAP-intervention minimizes risk of selection bias and confounders. Furthermore, hemodynamic characteristics and associations with outcome will be investigated.

TRIAL REGISTRATION

ClinicalTrials.gov (ClinicalTrials.gov Identifier: NCT03141099). Registered March 30, 2017.

Increasing mean arterial pressure or cardiac output in comatose out-of-hospital cardiac arrest patients undergoing targeted temperature management: Effects on cerebral tissue oxygenation and systemic hemodynamics

INTRODUCTION

Few data exist on the effects of increasing norepinephrine doses or increasing arterial CO2 (PaCO2) on hemodynamics and cerebral oxygenation in comatose out-of-hospital cardiac arrest (OHCA) patients.

METHODS

We prospectively studied 10 resuscitated OHCA-patients undergoing targeted temperature management (36C°). The trial consisted of 5 phases with 20 minutes steady state in-between: Phase 1-4 were increasing doses of norepinephrine to reach targets of mean arterial pressure (MAP). First 65, second 75, third 85, fourth 65 mmHg again. In the fifth phase, MAP was constant while PaCO2 was increased to 6.5-7.3 kPa to increase cardiac output. Primary outcome was cerebral near-infrared spectroscopy (NIRS). Secondary outcomes were hemodynamic variables from Swan-Ganz catheters and blood samples from the radial artery and jugular bulb.

RESULTS

To reach a MAP at 85 mmHg, norepinephrine was increased from 0.11 ± 0.02 to 0.18 ± 0.02 µg/kg/min (P < 0.001). Norepinephrine uptitration significantly increased systemic vascular resistance (SVR) and pulmonary vascular resistance, without affecting cardiac output, heart rate or cerebral oxygenation. Increasing PaCO2, resulted in a significant increase in cardiac output and cerebral NIRS, but arterial-venous cerebral oxygen-uptake decreased. Norepinephrine demand to keep MAP at 65 mmHg was unaffected by increasing PaCO2.

CONCLUSIONS

A short-term increase in MAP with norepinephrine in resuscitated comatose cardiac arrest-patients is associated with increased SVR and pulmonary vascular resistance without affecting cardiac output or cerebral NIRS. Increased cardiac output caused by an increase in PaCO2 increased cerebral NIRS, but not cerebral oxygen uptake.