Fetal factors disrupt placental and maternal iron homeostasis in murine ß-thalassemia.

Pregnancy rates in ß-thalassemia are increasing but the risk of complications is higher; thus, better understanding of maternal and fetal iron homeostasis in this disorder is needed. HbbTh3/+ (Th3/+) mice model human ß-thalassemia. Both the murine and human diseases are characterized by low hepcidin, high iron absorption, and tissue iron overload, with concurrent anemia. We hypothesized that disordered iron metabolism in pregnant Th3/+ mice would negatively affect their unborn offspring. The experimental design included these groups: wild-type (WT) dams carrying WT fetuses (WT1); WT dams carrying WT and Th3/+ fetuses (WT2); Th3/+ dams carrying WT and Th3/+ fetuses (Th3/+); and age-matched, nonpregnant adult females. Serum hepcidin was low, and mobilization of splenic and hepatic storage iron was enhanced in all 3 groups of experimental dams. Intestinal 59Fe absorption was lower in Th3/+ dams (as compared with WT1/2 dams) but splenic 59Fe uptake was higher. Th3/+ dams had hyperferremia, which led to fetal and placenta iron loading, fetal growth restriction, and placentomegaly. Notably, Th3/+ dams loaded Th3/+ and WT fetuses, with the latter situation more closely mirroring human circumstances when mothers with thalassemia have relatively unaffected (thalassemia trait) offspring. Iron-related oxidative stress likely contributed to fetal growth impairment; enhanced placental erythropoiesis is a probable cause of placental enlargement. Moreover, high fetal liver iron transactivated Hamp; fetal hepcidin downregulated placental ferroportin expression, limiting placental iron flux and thus mitigating fetal iron loading. Whether gestational iron loading occurs in human thalassemic pregnancy, when blood transfusion can further elevate serum iron, is worth consideration.

Neuroprotection provided by hypothermia initiated with high transnasal flow with ambient air in a model of pediatric cardiac arrest.

Clinical trials of hypothermia after pediatric cardiac arrest (CA) have not seen robust improvement in functional outcome, possibly because of the long delay in achieving target temperature. Previous work in infant piglets showed that high nasal airflow, which induces evaporative cooling in the nasal mucosa, reduced regional brain temperature uniformly in half the time needed to reduce body temperature. Here, we evaluated whether initiation of hypothermia with high transnasal airflow provides neuroprotection without adverse effects in the setting of asphyxic CA. Anesthetized piglets underwent sham-operated procedures (n = 7) or asphyxic CA with normothermic recovery (38.5°C; n = 9) or hypothermia initiated by surface cooling at 10 (n = 8) or 120 (n = 7) min or transnasal cooling initiated at 10 (n = 7) or 120 (n = 7) min after resuscitation. Hypothermia was sustained at 34°C with surface cooling until 20 h followed by 6 h of rewarming. At 4 days of recovery, significant neuronal loss occurred in putamen and sensorimotor cortex. Transnasal cooling initiated at 10 min significantly rescued the number of viable neurons in putamen, whereas levels in putamen in other hypothermic groups remained less than sham levels. In sensorimotor cortex, neuronal viability in the four hypothermic groups was not significantly different from the sham group. These results demonstrate that early initiation of high transnasal airflow in a pediatric CA model is effective in protecting vulnerable brain regions. Because of its simplicity, portability, and low cost, transnasal cooling potentially could be deployed in the field or emergency room for early initiation of brain cooling after pediatric CA.NEW & NOTEWORTHY The onset of therapeutic hypothermia after cardiac resuscitation is often delayed, leading to incomplete neuroprotection. In an infant swine model of asphyxic cardiac arrest, initiation of high transnasal airflow to maximize nasal evaporative cooling produced hypothermia sufficient to provide neuroprotection that was not inferior to body surface cooling. Because of its simplicity and portability, this technique may be of use in the field or emergency room for rapid brain cooling in pediatric cardiac arrest victims.

Association of diastolic blood pressure with coronary perfusion pressure during resuscitation in pediatric swine.

BACKGROUND: Diastolic blood pressure (DBP) is suggested as a surrogate for coronary perfusion pressure (CPP) during cardiopulmonary resuscitation. We examined the correlation between DBP and CPP and hypothesized that both would be associated with survival in a pediatric swine model of asphyxial cardiac arrest. METHODS: We performed a retrospective, secondary analysis of 102 pediatric swine resuscitations. DBP and CPP were recorded every 30 s during resuscitation. Values were compared between survivors and non-survivors. RESULTS: DBP mirrored CPP in survivors and non-survivors throughout resuscitation and both were associated with survival. Improvements in DBP and CPP after the first epinephrine administration were greater in survivors (DBP: 25.1 ± 3.0 vs. 5.4 ± 0.8 mmHg, p < 0.01; CPP: 24.9 ± 3.2 vs. 4.8 ± 0.9 mmHg, p < 0.01). DBP and CPP after epinephrine administration were highly predictive of survival, with an area under the curve of 0.95 (0.89-1.00) for DBP and 0.90 (0.81-0.99) for CPP. The optimal threshold for DBP was 22.5 mmHg, whereas that for CPP was 14.5 mmHg. CONCLUSIONS: DBP and CPP were associated with survival throughout resuscitation, and the response of both to the first epinephrine administration was highly predictive of survival in this model. Clinically, the availability of DBP makes it useful as a target for physiologic feedback during resuscitation. IMPACT: Diastolic blood pressure (DBP) mirrored coronary perfusion pressure (CPP) throughout prolonged resuscitation in a pediatric model of asphyxial cardiac arrest. Mean DBP and CPP were significantly greater in survivors than in non-survivors both before and after administration of epinephrine. The response of both DBP and CPP to the first dose of epinephrine was highly predictive of return of spontaneous circulation. Given the clinical availability of DBP, these findings support its use as a surrogate for CPP to guide high-quality cardiopulmonary resuscitation in this pediatric swine model.

Staying Virtual: A Survey Study of the Virtual Lecture Experience in Academic Medicine.

BACKGROUND: Increasing clinical demands can adversely impact academic advancement, including the ability to deliver lectures and disseminate scholarly work. The virtual lecture platform became mainstream during the height of the coronavirus-19 pandemic. Lessons learned from this period may offer insight into supporting academic productivity among physicians who must balance multiple demands, including high clinical workloads and family care responsibilities. We evaluated perceptions on delivering virtual lectures to determine whether virtual venues merit continuation beyond the pandemic's initial phase and whether these perceptions differ by gender and rank. METHODS: In a survey study, faculty who spoke in 1 of 3 virtual lecture programs in the Departments of Anesthesiology and Critical Care Medicine, Otolaryngology, and Radiology at a university hospital in 2020 to 2022 were queried about their experience. Speakers' motivations to lecture virtually and the perceived advantages and disadvantages of virtual and in-person lectures were analyzed using descriptive statistics and qualitative analyses. RESULTS: Seventy-two of 95 (76%) faculty members responded (40% women, 38% men, and 22% gender undisclosed). Virtual lectures supported the speakers "a lot" to "extremely" with the following goals: enhancing one's reputation and credibility (76%), networking (70%), receiving feedback (63%), and advancing prospects for promotion (59%). Virtual programs also increased the speakers' sense of accomplishment (70%) and professional optimism (61%) by at least "a lot," including instructors and assistant professors who previously had difficulty obtaining invitations to speak outside their institution. Many respondents had declined prior invitations to speak in-person due to clinical workload (66%) and family care responsibilities (58%). Previous opportunities to lecture in-person were also refused due to finances (39%), teaching (26%), and research (19%) requirements, personal medical conditions or disabilities (9%), and religious obligations (5%). Promotion was a stronger motivating factor to lecture virtually for instructors and assistant professors than for associate and full professors. By contrast, disseminating work and ideas was a stronger motivator for associate and full professors. Associate and full professors also reported greater improvement in work-related well-being than earlier career faculty from the virtual lecture experience. Very few differences were found by gender. CONCLUSIONS: Virtual lecture programs support faculty who might not otherwise have the opportunity to lecture in-person due to multiple constraints. To increase the dissemination of scholarly work and expand opportunities to all faculty, virtual lectures should continue even as in-person venues are reestablished.

Diverging roles for Lrp4 and Wnt signaling in neuromuscular synapse development during evolution.

Motor axons approach muscles that are prepatterned in the prospective synaptic region. In mice, prepatterning of acetylcholine receptors requires Lrp4, a LDLR family member, and MuSK, a receptor tyrosine kinase. Lrp4 can bind and stimulate MuSK, strongly suggesting that association between Lrp4 and MuSK, independent of additional ligands, initiates prepatterning in mice. In zebrafish, Wnts, which bind the Frizzled (Fz)-like domain in MuSK, are required for prepatterning, suggesting that Wnts may contribute to prepatterning and neuromuscular development in mammals. We show that prepatterning in mice requires Lrp4 but not the MuSK Fz-like domain. In contrast, prepatterning in zebrafish requires the MuSK Fz-like domain but not Lrp4. Despite these differences, neuromuscular synapse formation in zebrafish and mice share similar mechanisms, requiring Lrp4, MuSK, and neuronal Agrin but not the MuSK Fz-like domain or Wnt production from muscle. Our findings demonstrate that evolutionary divergent mechanisms establish muscle prepatterning in zebrafish and mice.

Plasma Biomarkers of Evolving Encephalopathy and Brain Injury in Neonates with Hypoxic-Ischemic Encephalopathy.

OBJECTIVE: The objective of the study was to evaluate the relationship between a panel of candidate plasma biomarkers and (1) death or severe brain injury on magnetic resonance imaging (MRI) and (2) dysfunctional cerebral pressure autoregulation as a measure of evolving encephalopathy. STUDY DESIGN: Neonates with moderate-to-severe hypoxic-ischemic encephalopathy (HIE) at 2 level IV neonatal intensive care units were enrolled into this observational study. Patients were treated with therapeutic hypothermia (TH) and monitored with continuous blood pressure monitoring and near-infrared spectroscopy. Cerebral pressure autoregulation was measured by the hemoglobin volume phase (HVP) index; a higher HVP index indicates poorer autoregulation. Serial blood samples were collected during TH and assayed for Tau, glial fibrillary acidic protein, and neurogranin. MRIs were assessed using National Institutes of Child Health and Human Development scores. The relationships between the candidate biomarkers and (1) death or severe brain injury on MRI (defined as a National Institutes of Child Health and Human Development score of ≥ 2B) and (2) autoregulation were evaluated using bivariate and adjusted logistic regression models. RESULTS: Sixty-two patients were included. Elevated Tau levels on days 2-3 of TH were associated with death or severe injury on MRI (aOR: 1.06, 95% CI: 1.03-1.09; aOR: 1.04, 95% CI: 1.01-1.06, respectively). Higher Tau was also associated with poorer autoregulation (higher HVP index) on the same day (P = .022). CONCLUSIONS: Elevated plasma levels of Tau are associated with death or severe brain injury by MRI and dysfunctional cerebral autoregulation in neonates with HIE. Larger-scale validation of Tau as a biomarker of brain injury in neonates with HIE is warranted.

Evaluating the Women's Empowerment and Leadership Initiative: Supporting mentorship, career satisfaction, and well-being among pediatric anesthesiologists.

The Society for Pediatric Anesthesia launched the Women's Empowerment and Leadership Initiative (WELI) in 2018 to empower highly productive women pediatric anesthesiologists to achieve equity, promotion, and leadership. WELI is focused on six career development domains: promotion and leadership, networking, conceptualization and completion of projects, mentoring, career satisfaction, and sense of well-being. We sought feedback about whether WELI supported members' career development by surveys emailed in November 2020 (baseline), May 2021 (6 months), and January 2022 (14 months). Program feedback was quantitatively evaluated by the Likert scale questions and qualitatively evaluated by extracting themes from free-text question responses. The response rates were 60.5% (92 of 152) for the baseline, 51% (82 of 161) for the 6-month, and 52% (96 of 185) for the 14-month surveys. Five main themes were identified from the free-text responses in the 6- and 14-month surveys. Members reported that WELI helped them create meaningful connections through networking, obtain new career opportunities, find tools and projects that supported their career advancement and promotion, build the confidence to try new things beyond their comfort zone, and achieve better work-life integration. Frustration with the inability to connect in-person during the coronavirus-19 pandemic was highlighted. Advisors further stated that WELI helped them improve their mentorship skills and gave them insight into early career faculty issues. Relative to the baseline survey, protégés reported greater contributions from WELI at 6 months in helping them clarify their priorities, increase their sense of achievement, and get promoted. These benefits persisted through 14 months. Advisors reported a steady increase in forming new meaningful relationships and finding new collaborators through WELI over time. All the members reported that their self-rated mentoring abilities improved at 6 months with sustained improvement at 14 months. Thus, programs such as WELI can assist women anesthesiologists and foster gender equity in career development, promotion, and leadership.

The Utility of Cerebral Autoregulation Indices in Detecting Severe Brain Injury Varies by Cooling Treatment Phase in Neonates with Hypoxic-Ischemic Encephalopathy.

Identifying the hemodynamic range that best supports cerebral perfusion using near infrared spectroscopy (NIRS) autoregulation monitoring is a potential physiologic marker for neonatal hypoxic-ischemic encephalopathy (HIE) during therapeutic hypothermia. However, an optimal autoregulation monitoring algorithm has not been identified for neonatal clinical medicine. We tested whether the hemoglobin volume phase (HVP), hemoglobin volume (HVx), and pressure passivity index (PPI) identify changes in autoregulation that are associated with brain injury on MRI or death. The HVP measures the phase difference between a NIRS metric of cerebral blood volume, the total hemoglobin (THb), and mean arterial blood pressure (MAP) at the frequency of maximum coherence. The HVx is the correlation coefficient between MAP and THb. The PPI is the percentage of coherent MAP-DHb (difference between oxygenated and deoxygenated hemoglobin, a marker of cerebral blood flow) epochs in a chosen time period. Neonates cooled for HIE were prospectively enrolled in an observational study in two neonatal intensive care units. In analyses adjusted for study site and encephalopathy level, all indices detected relationships between poor autoregulation in the first 6 h after rewarming with a higher injury score on MRI. Only HVx and PPI during hypothermia and the PPI during rewarming identified autoregulatory dysfunction associated with a poor outcome independent of study site and encephalopathy level. Our findings suggest that the accuracy of mathematical autoregulation algorithms in detecting the risk of brain injury or death may depend on temperature and postnatal age. Extending autoregulation monitoring beyond the standard 72 h of therapeutic hypothermia may serve as a method to provide personalized care by assessing the need for and efficacy of future therapies after the hypothermia treatment phase.

Comparison of different metrics of cerebral autoregulation in association with major morbidity and mortality after cardiac surgery.

BACKGROUND: Cardiac surgery studies have established the clinical relevance of personalised arterial blood pressure management based on cerebral autoregulation. However, variabilities exist in autoregulation evaluation. We compared the association of several cerebral autoregulation metrics, calculated using different methods, with outcomes after cardiac surgery. METHODS: Autoregulation was measured during cardiac surgery in 240 patients. Mean flow index and cerebral oximetry index were calculated as Pearson's correlations between mean arterial pressure (MAP) and transcranial Doppler blood flow velocity or near-infrared spectroscopy signals. The lower limit of autoregulation and optimal mean arterial pressure were identified using mean flow index and cerebral oximetry index. Regression models were used to examine associations of area under curve and duration of mean arterial pressure below thresholds with stroke, acute kidney injury (AKI), and major morbidity and mortality. RESULTS: Both mean flow index and cerebral oximetry index identified the cerebral lower limit of autoregulation below which MAP was associated with a higher incidence of AKI and major morbidity and mortality. Based on magnitude and significance of the estimates in adjusted models, the area under curve of MAP < lower limit of autoregulation had the strongest association with AKI and major morbidity and mortality. The odds ratio for area under the curve of MAP < lower limit of autoregulation was 1.05 (95% confidence interval, 1.01-1.09), meaning every 1 mm Hg h increase of area under the curve was associated with an average increase in the odds of AKI by 5%. CONCLUSIONS: For cardiac surgery patients, area under curve of MAP < lower limit of autoregulation using mean flow index or cerebral oximetry index had the strongest association with AKI and major morbidity and mortality. Trials are necessary to evaluate this target for MAP management.

The neurosurgical management of Severe Hemophilia A and Moyamoya (SHAM): challenges, strategies, and literature review.

INTRODUCTION: Severe Hemophilia A and Moyamoya arteriopathy (SHAM syndrome) is a rare genetic disorder caused by deletion of portions of the cytogenic band Xq28. A case of SHAM syndrome requiring bilateral cerebral revascularization is described with an emphasis on perioperative management. CASE REPORT: A 5-year-old boy with severe hemophilia A complicated by factor VIII inhibition presented with right-sided weakness. Imaging revealed multiple strokes and vascular changes consistent with Moyamoya disease. The patient underwent two-staged indirect cerebral bypass revascularizations, first on the left side and several months later on the right. Perioperative management required balancing the administration of agents to prevent coagulopathy and perioperative hemorrhage while mitigating the risk of thromboembolic events associated with bypass surgery. Despite a multidisciplinary effort by the neurosurgery, hematology, critical care, and anesthesiology teams, the post-operative course after both surgeries was complicated by stroke. Fortunately, the patient recovered rapidly to his preoperative functional baseline. CONCLUSION: We describe a rare case of SHAM syndrome in a pediatric patient who required bilateral revascularizations and discuss strategies for managing the perioperative risk of hemorrhage and stroke. We also review existing literature on SHAM syndrome.

Lowering n-6/n-3 Ratio as an Important Dietary Intervention to Prevent LPS-Inducible Dyslipidemia and Hepatic Abnormalities in ob/ob Mice.

Obesity is closely associated with low-grade chronic and systemic inflammation and dyslipidemia, and the consumption of omega-3 polyunsaturated fatty acids (n-3 PUFAs) may modulate obesity-related disorders, such as inflammation and dyslipidemia. An emerging research question is to understand the dietary intervention strategy that is more important regarding n-3 PUFA consumption: (1) a lower ratio of n-6/n-3 PUFAs or (2) a higher amount of n-3 PUFAs consumption. To understand the desirable dietary intervention method of n-3 PUFAs consumption, we replaced lard from the experimental diets with either perilla oil (PO) or corn oil (CO) to have identical n-3 amounts in the experimental diets. PO had a lower n-6/n-3 ratio, whereas CO contained higher amounts of PUFAs; it inherently contained relatively lower n-3 but higher n-6 PUFAs than PO. After the 12-week dietary intervention in ob/ob mice, dyslipidemia was observed in the normal chow and CO-fed ob/ob mice; however, PO feeding increased the high density lipoprotein-cholesterol (HDL-C) level; further, not only did the HDL-C level increase, the low density lipoprotein-cholesterol (LDL-C) and triglyceride (TG) levels also decreased significantly after lipopolysaccharide (LPS) injection. Consequently, extra TG accumulated in the liver and white adipose tissue (WAT) of normal chow- or CO-fed ob/ob mice after LPS injection; however, PO consumption decreased serum TG accumulation in the liver and WAT. PUFAs replacement attenuated systemic inflammation induced by LPS injection by increasing anti-inflammatory cytokines but inhibiting pro-inflammatory cytokine production in the serum and WAT. PO further decreased hepatic inflammation and fibrosis in comparison with the ND and CO. Hepatic functional biomarkers (aspartate aminotransferase (AST) and alanine transaminase (ALT) levels) were also remarkably decreased in the PO group. In LPS-challenged ob/ob mice, PO and CO decreased adipocyte size and adipokine secretion, with a reduction in phosphorylation of MAPKs compared to the ND group. In addition, LPS-inducible endoplasmic reticulum (ER) and oxidative stress decreased with consumption of PUFAs. Taken together, PUFAs from PO and CO play a role in regulating obesity-related disorders. Moreover, PO, which possesses a lower ratio of n-6/n-3 PUFAs, remarkably alleviated metabolic dysfunction in LPS-induced ob/ob mice. Therefore, an interventional trial considering the ratio of n-6/n-3 PUFAs may be desirable for modulating metabolic complications, such as inflammatory responses and ER stress in the circulation, liver, and/or WAT.

Targeting the mitochondrial permeability transition pore for neuroprotection in a piglet model of neonatal hypoxic-ischemic encephalopathy.

Neonatal hypoxic-ischemic encephalopathy (HIE) causes significant morbidity despite treatment with therapeutic hypothermia. Mitochondrial dysfunction may drive the mechanisms underlying neuronal cell death, thereby making mitochondria prime targets for neuroprotection. The mitochondrial permeability transition pore (mPTP) is one such target within mitochondria. In adult animal models, mPTP inhibition is neuroprotective. However, evidence for mPTP inhibition in neonatal models of neurologic disease is less certain. We tested the therapeutic efficacy of the mPTP small molecule inhibitor GNX-4728 and examined the developmental presence of brain mPTP proteins for drug targeting in a neonatal piglet model of hypoxic-ischemic brain injury. Male neonatal piglets were randomized to hypoxia-ischemia (HI) or sham procedure with GNX-4728 (15 mg/kg, IV) or vehicle (saline/cyclodextrin/DMSO, IV). GNX-4728 was administered as a single dose within 5 min after resuscitation from bradycardic arrest. Normal, ischemic, and injured neurons were counted in putamen and somatosensory cortex using hematoxylin and eosin staining. In separate neonatal and juvenile pigs, western blots of putamen mitochondrial-enriched fractions were used to evaluate mitochondrial integrity and the presence of mPTP proteins. We found that a single dose of GNX-4728 did not protect putamen and cortical neurons from cell death after HI. However, loss of mitochondrial matrix integrity occurred within 6h after HI, and while mPTP components are present in the neonatal brain their levels were significantly different compared to that of a mature juvenile brain. Thus, the neonatal brain mPTP may not be a good target for current neurotherapeutic drugs that are developed based on adult mitochondria.

Determining Thresholds for Three Indices of Autoregulation to Identify the Lower Limit of Autoregulation During Cardiac Surgery.

OBJECTIVES: Monitoring cerebral autoregulation may help identify the lower limit of autoregulation in individual patients. Mean arterial blood pressure below lower limit of autoregulation appears to be a risk factor for postoperative acute kidney injury. Cerebral autoregulation can be monitored in real time using correlation approaches. However, the precise thresholds for different cerebral autoregulation indexes that identify the lower limit of autoregulation are unknown. We identified thresholds for intact autoregulation in patients during cardiopulmonary bypass surgery and examined the relevance of these thresholds to postoperative acute kidney injury. DESIGN: A single-center retrospective analysis. SETTING: Tertiary academic medical center. PATIENTS: Data from 59 patients was used to determine precise cerebral autoregulation thresholds for identification of the lower limit of autoregulation. These thresholds were validated in a larger cohort of 226 patients. METHODS AND MAIN RESULTS: Invasive mean arterial blood pressure, cerebral blood flow velocities, regional cortical oxygen saturation, and total hemoglobin were recorded simultaneously. Three cerebral autoregulation indices were calculated, including mean flow index, cerebral oximetry index, and hemoglobin volume index. Cerebral autoregulation curves for the three indices were plotted, and thresholds for each index were used to generate threshold- and index-specific lower limit of autoregulations. A reference lower limit of autoregulation could be identified in 59 patients by plotting cerebral blood flow velocity against mean arterial blood pressure to generate gold-standard Lassen curves. The lower limit of autoregulations defined at each threshold were compared with the gold-standard lower limit of autoregulation determined from Lassen curves. The results identified the following thresholds: mean flow index (0.45), cerebral oximetry index (0.35), and hemoglobin volume index (0.3). We then calculated the product of magnitude and duration of mean arterial blood pressure less than lower limit of autoregulation in a larger cohort of 226 patients. When using the lower limit of autoregulations identified by the optimal thresholds above, mean arterial blood pressure less than lower limit of autoregulation was greater in patients with acute kidney injury than in those without acute kidney injury. CONCLUSIONS: This study identified thresholds of intact and impaired cerebral autoregulation for three indices and showed that mean arterial blood pressure below lower limit of autoregulation is a risk factor for acute kidney injury after cardiac surgery.

Quantitative validation of MRI mapping of cerebral venous oxygenation with direct blood sampling: A graded-O2 study in piglets.

PURPOSE: To validate two neonatal cerebral venous oxygenation (Yv ) MRI techniques, T2 relaxation under phase contrast (TRUPC) and accelerated TRUPC (aTRUPC) MRI, with oxygenation measured with direct blood sampling. METHODS: In vivo experiments were performed on seven healthy newborn piglets. For each piglet, a catheter was placed in the superior sagittal sinus to obtain venous blood samples for blood gas oximetry measurement as a gold standard. During the MRI experiment, three to five venous oxygenation levels were achieved in each piglet by varying inhaled O2 content and breathing rate. Under each condition, Yv values of the superior sagittal sinus measured by TRUPC, aTRUPC, and blood gas oximetry were obtained. The Yv quantification in TRUPC and aTRUPC used a standard bovine blood calibration model. The aTRUPC scan was repeated twice to assess its reproducibility. Agreements among TRUPC Yv , aTRUPC Yv , and blood gas oximetry were evaluated by intraclass correlation coefficient (ICC) and paired Student's t-test. RESULTS: The mean hematocrit was 23.6 ± 6.5% among the piglets. Across all measurements, Yv values were 51.9 ± 21.3%, 54.1 ± 18.8%, and 53.7 ± 19.2% for blood gas oximetry, TRUPC and aTRUPC, respectively, showing no significant difference between any two methods (P > .3). There were good correlations between TRUPC and blood gas Yv (ICC = 0.801; P < .0001), between aTRUPC and blood gas Yv (ICC = 0.809; P < .0001), and between aTRUPC and TRUPC Yv (ICC = 0.887; P < .0001). The coefficient of variation of aTRUPC Yv was 8.1 ± 9.9%. CONCLUSION: The values of Yv measured by TRUPC and aTRUPC were in good agreement with blood gas oximetry. These findings suggest that TRUPC and aTRUPC can provide accurate quantifications of Yv in major cerebral veins.

Multi-Parametric Evaluation of Cerebral Hemodynamics in Neonatal Piglets Using Non-Contrast-Enhanced Magnetic Resonance Imaging Methods.

BACKGROUND: Disruption of brain oxygen delivery and consumption after hypoxic-ischemic injury contributes to neonatal mortality and neurological impairment. Measuring cerebral hemodynamic parameters, including cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2 ), is clinically important. PURPOSE: Phase-contrast (PC), velocity-selective arterial spin labeling (VSASL), and T2 -relaxation-under-phase-contrast (TRUPC) are magnetic resonance imaging (MRI) techniques that have shown promising results in assessing cerebral hemodynamics in humans. We aimed to test their feasibility in quantifying CBF, OEF, and CMRO2 in piglets. STUDY TYPE: Prospective. ANIMAL MODEL: Ten neonatal piglets subacutely recovered from global hypoxia-ischemia (N = 2), excitotoxic brain injury (N = 6), or sham procedure (N = 2). FIELD STRENGTH/SEQUENCE: VSASL, TRUPC, and PC MRI acquired at 3.0 T. ASSESSMENT: Regional CBF was measured by VSASL. Global CBF was quantified by both PC and VSASL. TRUPC assessed OEF at the superior sagittal sinus (SSS) and internal cerebral veins (ICVs). CMRO2 was calculated from global CBF and SSS-derived OEF. End-tidal carbon dioxide (EtCO2 ) levels of the piglets were also measured. Brain damage was assessed in tissue sections postmortem by counting damaged neurons. STATISTICAL TESTS: Spearman correlations were performed to evaluate associations among CBF (by PC or VSASL), OEF, CMRO2 , EtCO2 , and the pathological neuron counts. Paired t-test was used to compare OEF at SSS with OEF at ICV. RESULTS: Global CBF was 32.1 ± 14.9 mL/100 g/minute and 30.9 ± 8.3 mL/100 g/minute for PC and VSASL, respectively, showing a significant correlation (r = 0.82, P < 0.05). OEF was 54.9 ± 8.8% at SSS and 46.1 ± 5.6% at ICV, showing a significant difference (P < 0.05). Global CMRO2 was 79.1 ± 26.2 µmol/100 g/minute and 77.2 ± 12.2 µmol/100 g/minute using PC and VSASL-derived CBF, respectively. EtCO2 correlated positively with PC-based CBF (r = 0.81, P < 0.05) but negatively with OEF at SSS (r = -0.84, P < 0.05). Relative CBF of subcortical brain regions and OEF at ICV did not significantly correlate, respectively, with the ratios of degenerating-to-total neurons (P = 0.30, P = 0.10). DATA CONCLUSION: Non-contrast MRI can quantify cerebral hemodynamic parameters in normal and brain-injured neonatal piglets. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 2.

Later cooling within 6 h and temperatures outside 33-34 °C are not associated with dysfunctional autoregulation during hypothermia for neonatal encephalopathy.

BACKGROUND: Cooling delays, temperature outside 33-34 °C, and blood pressure below the mean arterial blood pressure with optimal cerebral autoregulation (MAPOPT) might diminish neuroprotection from therapeutic hypothermia in neonates with hypoxic-ischemic encephalopathy (HIE). We hypothesized that longer time to reach temperature <34 °C and having temperature outside 33-34 °C would be associated with worse autoregulation and greater brain injury. METHODS: Neonates with HIE had rectal temperature and near-infrared spectroscopy autoregulation monitoring during hypothermia (n = 63) and rewarming (n = 58). All underwent brain MRI, and a subset received diffusion tensor imaging MRI before day 10 (n = 41). RESULTS: Most neonates reached <34 °C at 3-6 h of life. MAPOPT was identified in 54/63 (86%) during hypothermia and in 53/58 (91%) during rewarming. Cooling time was not related to blood pressure deviation from MAPOPT. Later cooling was associated with lower ADC scalar in unilateral posterior centrum semiovale but not in other regions. Temperatures >34 °C were associated with blood pressure above MAPOPT but not with brain injury. CONCLUSIONS: In neonates who were predominantly cooled after 3 h, cooling time was not associated with autoregulation or overall brain injury. Blood pressure deviation above MAPOPT was associated with temperature >34 °C. Additional studies are needed in a more heterogeneous population. IMPACT: Cooling time to reach target hypothermia temperature within 6 h of birth did not affect cerebral autoregulation measured by NIRS in neonates with hypoxic-ischemic encephalopathy (HIE). Temperature fluctuations >33-34 °C were associated with blood pressures that exceeded the range of optimal autoregulatory vasoreactivity. Cooling time within 6 h of birth and temperatures >33-34 °C were not associated with qualitative brain injury on MRI. Regional apparent diffusion coefficient scalars on diffusion tensor imaging MRI were not appreciably affected by cooling time or temperature >33-34 °C. Additional research in a larger and more heterogeneous population is needed to determine how delayed cooling and temperatures beyond the target hypothermia range affect autoregulation and brain injury.

Empowering Women as Leaders in Pediatric Anesthesiology: Methodology, Lessons, and Early Outcomes of a National Initiative.

Research has shown that women have leadership ability equal to or better than that of their male counterparts, yet proportionally fewer women than men achieve leadership positions and promotion in medicine. The Women's Empowerment and Leadership Initiative (WELI) was founded within the Society for Pediatric Anesthesia (SPA) in 2018 as a multidimensional program to help address the significant career development, leadership, and promotion gender gap between men and women in anesthesiology. Herein, we describe WELI's development and implementation with an early assessment of effectiveness at 2 years. Members received an anonymous, voluntary survey by e-mail to assess whether they believed WELI was beneficial in several broad domains: career development, networking, project implementation and completion, goal setting, mentorship, well-being, and promotion and leadership. The response rate was 60.5% (92 of 152). The majority ranked several aspects of WELI to be very or extremely valuable, including the protégé-advisor dyads, workshops, nomination to join WELI, and virtual facilitated networking. For most members, WELI helped to improve optimism about their professional future. Most also reported that WELI somewhat or absolutely contributed to project improvement or completion, finding new collaborators, and obtaining invitations to be visiting speakers. Among those who applied for promotion or leadership positions, 51% found WELI to be somewhat or absolutely valuable to their application process, and 42% found the same in applying for leadership positions. Qualitative analysis of free-text survey responses identified 5 main themes: (1) feelings of empowerment and confidence, (2) acquisition of new skills in mentoring, coaching, career development, and project implementation, (3) clarification and focus on goal setting, (4) creating meaningful connections through networking, and (5) challenges from coronavirus disease 2019 (COVID-19) and the inability to sustain the advisor-protégé connection. We conclude that after 2 years, the WELI program has successfully supported career development for the majority of protégés and advisors. Continued assessment of whether WELI can meaningfully contribute to attainment of promotion and leadership positions will require study across a longer period. WELI could serve as a programmatic example to support women's career development in other subspecialties.

Coaching for the pediatric anesthesiologist: Becoming our best selves.

Anesthesiologists must balance demanding clinical workloads with career development goals. Leadership, conflict management, and other skills can improve medical outcomes, reduce stress at work, and increase career satisfaction. However, Medicine in general and Anesthesiology in particular have not traditionally emphasized physician growth in these areas. Coaching utilizes concepts from psychology, adult learning, and adult development theory to support an individual in personal and professional growth through inquiry, reflection, and shared discovery. This manuscript reviews the history and evidence basis for coaching, differentiates coaching from traditional mentorship, and presents some constructs of coaching and working with a coach. An example of a successful pilot program to disseminate coaching skills and support leadership growth among anesthesiologists, the Women's Empowerment and Leadership Initiative within the Society for Pediatric Anesthesia, is described.

Grow and Advance through Intentional Networking: A pilot program to foster connections within the Women's Empowerment and Leadership Initiative in the Society for Pediatric Anesthesia.

BACKGROUND: The Women's Empowerment and Leadership Initiative in the Society for Pediatric Anesthesia was established to support women's efforts to achieve promotion, leadership positions, and equity in pediatric anesthesiology through coaching, mentoring, sponsorship, and networking. Career advancement relies on the establishment of mentoring relationships within institutions and at regional and national levels. Prior to the SARS-CoV-2 (COVID-19) pandemic, networking was primarily conducted at large national meetings. AIMS: When national meetings were canceled by the COVID-19 pandemic, the Women's Empowerment and Leadership Initiative sought to reduce networking barriers by creating a pilot program called "Grow and Advance through Intentional Networking" (GAIN). MATERIALS & METHODS: Monthly 1-h virtual GAIN sessions were developed based on topics requested by the Women's Empowerment and Leadership Initiative members. Faculty facilitated psychologically safe small-group discussions to maximize engagement. RESULTS: We present an overview of our pilot GAIN program, which has been well received by the Women's Empowerment and Leadership Initiative members and met with continuous demand for more sessions. DISCUSSION: Professional networking is critical for career advancement and for developing and maintaining a sense of community and well-being. Early- and mid-career physicians depend on these relationships to facilitate academic productivity and promotion. CONCLUSION: Programs like the Women's Empowerment and Leadership Initiative GAIN are critical for advancing our specialty and supporting the well-being of pediatric anesthesiologists. GAIN addresses barriers to professional networking, including during the COVID-19 pandemic.

Lower Limit of Reactivity Assessed with PRx in an Experimental Setting.

In traumatic brain injury, longer time spent with a cerebral perfusion pressure (CPP) below the pressure reactivity index (PRx)-derived lower limit of reactivity (LLR) has been shown to be statistically associated with higher mortality. We set out to scrutinise the behaviour of LLR and the methods of its estimation in individual cases by performing retrospective analysis of intracranial pressure (ICP), arterial blood pressure (ABP) and laser Doppler flow (LDF) signals recorded in nine piglets undergoing controlled, terminal hypotension. We focused on the sections of the recordings with stable experimental conditions where a clear breakpoint of LDF/CPP characteristic (LLA) could be identified.In eight of the nine experiments, when CPP underwent a monotonous decrease, the relationship PRx/CPP showed two breakpoints (1 - when PRx starts to rise; 2 - when PRx saturates at PRx > 0.3), with LDF-based LLA sitting between them. LLR (CPP at PRx reaching 0.3 in the error bar chart) was close to the lower LLR breakpoint.In conclusion, when CPP has a monotonous decrease, PRx starts worsening before CPP crosses the LLA. A further decrease in CPP below LLA would cause a decrease in CBF, even if the pressure reactivity is not completely lost. This pattern should be taken into account when PRx is used to detect LLA continuously.