Correlation of Cerebral and Subcutaneous Glycerol in Severe Traumatic Brain Injury and Association with Tissue Damage

Normoxic Management during Cardiopulmonary Bypass Does Not Reduce Cerebral Mitochondrial Dysfunction in Neonatal Swine

Optimal oxygen management during pediatric cardiopulmonary bypass (CPB) is unknown. We previously demonstrated an increase in cortical mitochondrial reactive oxygen species and decreased mitochondrial function after CPB using hyperoxic oxygen management. This study investigates whether controlled oxygenation (normoxia) during CPB reduces cortical mitochondrial dysfunction and oxidative injury. Ten neonatal swine underwent three hours of continuous CPB at 34 °C (flow > 100 mL/kg/min) via cervical cannulation targeting a partial pressure of arterial oxygen (PaO2) goal < 150 mmHg (normoxia, n = 5) or >300 mmHg (hyperoxia, n = 5). The animals underwent continuous hemodynamic monitoring and serial arterial blood sampling. Cortical microdialysate was serially sampled to quantify the glycerol concentration (represents neuronal injury) and lactate-to-pyruvate ratio (represents bioenergetic dysfunction). The cortical tissue was analyzed via high-resolution respirometry to quantify mitochondrial oxygen consumption and reactive oxygen species generation, and cortical oxidized protein carbonyl concentrations were quantified to assess for oxidative damage. Serum PaO2 was higher in hyperoxia animals throughout CPB (p < 0.001). There were no differences in cortical glycerol concentration between groups (p > 0.2). The cortical lactate-to-pyruvate ratio was modestly elevated in hyperoxia animals (p < 0.03) but the values were not clinically significant (<30). There were no differences in cortical mitochondrial respiration (p = 0.48), protein carbonyls (p = 0.74), or reactive oxygen species generation (p = 0.93) between groups. Controlled oxygenation during CPB does not significantly affect cortical mitochondrial function or oxidative injury in the acute setting. Further evaluation of the short and long-term effects of oxygen level titration during pediatric CPB on cortical tissue and other at-risk brain regions are needed, especially in the presence of cyanosis.

Early Impairment of Cerebral Bioenergetics After Cardiopulmonary Bypass in Neonatal Swine

Objectives: We previously demonstrated cerebral mitochondrial dysfunction in neonatal swine immediately following a period of full-flow cardiopulmonary bypass (CPB). The extent to which this dysfunction persists in the postoperative period and its correlation with other markers of cerebral bioenergetic failure and injury is unknown. We utilized a neonatal swine model to investigate the early evolution of mitochondrial function and cerebral bioenergetic failure after CPB. Methods: Twenty piglets (mean weight 4.4 ± 0.5 kg) underwent 3 h of CPB at 34 °C via cervical cannulation and were followed for 8, 12, 18, or 24 h (n = 5 per group). Markers of brain tissue damage (glycerol) and bioenergetic dysfunction (lactate to pyruvate ratio) were continuously measured in cerebral microdialysate samples. Control animals (n = 3, mean weight 4.1 ± 1.2 kg) did not undergo cannulation or CPB. Brain tissue was extracted immediately after euthanasia to obtain ex-vivo cortical mitochondrial respiration and frequency of cortical microglial nodules (indicative of cerebral microinfarctions) via neuropathology. Results: Both the lactate to pyruvate ratio (P < .0001) and glycerol levels (P = .01) increased in cerebral microdialysate within 8 h after CPB. At 24 h post-CPB, cortical mitochondrial respiration was significantly decreased compared with controls (P = .046). The presence of microglial nodules increased throughout the study period (24 h) (P = .01, R2 = 0.9). Conclusion: CPB results in impaired cerebral bioenergetics that persist for at least 24 h. During this period of bioenergetic impairment, there may be increased susceptibility to secondary injury related to alterations in metabolic delivery or demand, such as hypoglycemia, seizures, and decreased cerebral blood flow.

Retrospective study on the correlation between serum MIF level and the condition and prognosis of patients with traumatic head injury

Objective

This study aimed to investigate the correlation between serum levels of macrophage migration inhibitory factor (MIF) and the condition and prognosis of patients with traumatic brain injury (TBI).

Methods

A retrospective study design was used, and the clinical data of 131 TBI patients from February 2019 to January 2022 were analyzed. Patients were divided into mild (13-15 points), moderate (9-12 points), or severe (3-8 points) groups according to their Glasgow Coma Scale (GCS) score after admission. The serum levels of BDNF, MIF, and MBP in the three groups were compared, and their correlation with the severity of TBI was analyzed. Patients were then separated into a good prognosis group (4-5 points) and a poor prognosis group (≤3 points) based on their Glasgow Prognostic Score (GOS) after 6 months of follow-up. The predictive power of serum indexes and combined detection on prognosis was analyzed.

Results

Patients were classified into a mild group (n = 63), moderate group (n = 47), and severe group (n = 21) based on their GCS, with a significant difference noted in serum levels of MIF, MBP, and BDNF among patients with different degrees of severity (all P < 0.001). The MIF, MBP, and BDNF levels were lower in the mild group compared to the moderate (all P < 0.001) and severe group (all P < 0.001). Additionally, the MIF and BDNF levels in the moderate group were lower compared to the severe group (P = 0.011, P = 0.002). Patients with mild severity had lower serum MIF, MBP, and BDNF levels than those with other degrees, and these indexes were positively correlated with the severity of TBI (all P < 0.001, r = 0.62, r = 0.48, r = 0.58). Based on the GOS, patients were divided into a good prognosis group (n = 107) and a poor prognosis group (n = 24), with the levels of MIF, MBP, and BDNF in the good prognosis group being significantly lower than those in the poor prognosis group (P < 0.001, P = 0.007, P = 0.003). The area under the curve (AUC) of MIF was higher than that of MBP and BDNF in predicting the prognosis of TBI patients; however, the statistical differences were not significant (MIF vs. MBP, P = 0.239; MIF vs. BDNF, P = 0.211; BDNF vs. MBP, P = 0.899). The center line has a large displacement, CT annular cisterna compression, increased white blood cell count, MBP and BDNF were risk factors for prognosis in TBI patients (P = 0.005, P = 0.001, P = 0.005, P = 0.033, P = 0.044).

Conclusion

The serum levels of MIF, MBP, and BDNF in TBI patients were positively correlated with the severity of the disease, and MBP, BDNF levels had predictive value in determining patient prognosis.

Correlation of Cerebral Microdialysis with Non-Invasive Diffuse Optical Cerebral Hemodynamic Monitoring during Deep Hypothermic Cardiopulmonary Bypass

Neonates undergoing cardiac surgery involving aortic arch reconstruction are at an increased risk for hypoxic-ischemic brain injury. Deep hypothermia is utilized to help mitigate this risk when periods of circulatory arrest are needed for surgical repair. Here, we investigate correlations between non-invasive optical neuromonitoring of cerebral hemodynamics, which has recently shown promise for the prediction of postoperative white matter injury in this patient population, and invasive cerebral microdialysis biomarkers. We compared cerebral tissue oxygen saturation (StO₂), relative total hemoglobin concentration (rTHC), and relative cerebral blood flow (rCBF) measured by optics against the microdialysis biomarkers of metabolic stress and injury (lactate–pyruvate ratio (LPR) and glycerol) in neonatal swine models of deep hypothermic cardiopulmonary bypass (DHCPB), selective antegrade cerebral perfusion (SACP), and deep hypothermic circulatory arrest (DHCA). All three optical parameters were negatively correlated with LPR and glycerol in DHCA animals. Elevation of LPR was found to precede the elevation of glycerol by 30–60 min. From these data, thresholds for the detection of hypoxic-ischemia-associated cerebral metabolic distress and neurological injury are suggested. In total, this work provides insight into the timing and mechanisms of neurological injury following hypoxic-ischemia and reports a quantitative relationship between hypoxic-ischemia severity and neurological injury that may inform DHCA management.