Cerebral blood flow (CBF) is rigorously regulated by various powerful mechanisms to safeguard the match between cerebral metabolic demand and supply. The question of how a change in cardiac output ...(CO) affects CBF is fundamental, because CBF is dependent on constantly receiving a significant proportion of CO. The authors reviewed the studies that investigated the association between CO and CBF in healthy volunteers and patients with chronic heart failure. The overall evidence shows that an alteration in CO, either acutely or chronically, leads to a change in CBF that is independent of other CBF-regulating parameters including blood pressure and carbon dioxide. However, studies on the association between CO and CBF in patients with varying neurologic, medical, and surgical conditions were confounded by methodologic limitations. Given that CBF regulation is multifactorial but the various processes must exert their effects on the cerebral circulation simultaneously, the authors propose a conceptual framework that integrates the various CBF-regulating processes at the level of cerebral arteries/arterioles while still maintaining autoregulation. The clinical implications pertinent to the effect of CO on CBF are discussed. Outcome research relating to the management of CO and CBF in high-risk patients or during high-risk surgeries is needed.
Certain CD4+CD25+ T cells can induce and maintain T-cell non-responsiveness to donor alloantigens and have therapeutic potential in solid organ transplantation. Peripheral CD4+CD25− cells ...alloactivated with IL-2 and transforming growth factor β (TGF-β) ex vivo express the transcription factor FoxP3, and become potent antigen-specific CD4+CD25− suppressor cells. Here we report that the transfer of TGF-β-induced regulatory CD4+ and CD8+ T cells (Tregs) co-incident with transplantation of a histoincompatible heart resulted in extended allograft survival. To account for this result, we injected non-transplanted mice with a single dose of CD4+ and CD8+ Tregs and transferred donor cells every 2 weeks to mimic the continuous stimulation of a transplant. We observed increased splenic CD4+CD25+ cells that were of recipient origin. These cells rendered the animals non-responsive to donor alloantigens by an antigen-specific and cytokine-dependent mechanism of action. Both the increased number of CD4+CD25+ cells and their tolerogenic effect were dependent on continued donor antigen boosting. Thus, Tregs generated ex vivo can act like a vaccine that generates host suppressor cells with the potential to protect MHC-mismatched organ grafts from rejection.
Various techniques have been employed for the early detection of perioperative cerebral ischaemia and hypoxia. Cerebral near-infrared spectroscopy (NIRS) is increasingly used in this clinical ...scenario to monitor brain oxygenation. However, it is unknown whether perioperative cerebral NIRS monitoring and the subsequent treatment strategies are of benefit to patients.
To assess the effects of perioperative cerebral NIRS monitoring and corresponding treatment strategies in adults and children, compared with blinded or no cerebral oxygenation monitoring, or cerebral oxygenation monitoring based on non-NIRS technologies, on the detection of cerebral oxygen desaturation events (CDEs), neurological outcomes, non-neurological outcomes and socioeconomic impact (including cost of hospitalization and length of hospital stay).
We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 12), Embase (1974 to 20 December 2016) and MEDLINE (PubMed) (1975 to 20 December 2016). We also searched the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing studies on 20 December 2016. We updated this search in November 2017, but these results have not yet been incorporated in the review. We imposed no language restriction.
We included all relevant randomized controlled trials (RCTs) dealing with the use of cerebral NIRS in the perioperative setting (during the operation and within 72 hours after the operation), including the operating room, the postanaesthesia care unit and the intensive care unit.
Two authors independently selected studies, assessed risk of bias and extracted data. For binary outcomes, we calculated the risk ratio (RR) and its 95% confidence interval (CI). For continuous data, we estimated the mean difference (MD) between groups and its 95% CI. As we expected clinical and methodological heterogeneity between studies, we employed a random-effects model for analyses and we examined the data for heterogeneity (I
statistic). We created a 'Summary of findings' table using GRADEpro.
We included 15 studies in the review, comprising a total of 1822 adult participants. There are 12 studies awaiting classification, and eight ongoing studies.None of the 15 included studies considered the paediatric population. Four studies were conducted in the abdominal and orthopaedic surgery setting (lumbar spine, or knee and hip replacement), one study in the carotid endarterectomy setting, and the remaining 10 studies in the aortic or cardiac surgery setting. The main sources of bias in the included studies related to potential conflict of interest from industry sponsorship, unclear blinding status or missing participant data.Two studies with 312 participants considered postoperative neurological injury, however no pooled effect estimate could be calculated due to discordant direction of effect between studies (low-quality evidence). One study (N = 126) in participants undergoing major abdominal surgery reported that 4/66 participants experienced neurological injury with blinded monitoring versus 0/56 in the active monitoring group. A second study (N = 195) in participants having coronary artery bypass surgery reported that 1/96 participants experienced neurological injury in the blinded monitoring group compared with 4/94 participants in the active monitoring group.We are uncertain whether active cerebral NIRS monitoring has an important effect on the risk of postoperative stroke because of the low number of events and wide confidence interval (RR 0.25, 95% CI 0.03 to 2.20; 2 studies, 240 participants; low-quality evidence).We are uncertain whether active cerebral NIRS monitoring has an important effect on postoperative delirium because of the wide confidence interval (RR 0.63, 95% CI 0.27 to 1.45; 1 study, 190 participants; low-quality evidence).Two studies with 126 participants showed that active cerebral NIRS monitoring may reduce the incidence of mild postoperative cognitive dysfunction (POCD) as defined by the original studies at one week after surgery (RR 0.53, 95% CI 0.30 to 0.95, I
= 49%, low-quality evidence).Based on six studies with 962 participants, there was moderate-quality evidence that active cerebral oxygenation monitoring probably does not decrease the occurrence of POCD (decline in cognitive function) at one week after surgery (RR 0.62, 95% CI 0.37 to 1.04, I
= 80%). The different type of monitoring equipment in one study could potentially be the cause of the heterogeneity.We are uncertain whether active cerebral NIRS monitoring has an important effect on intraoperative mortality or postoperative mortality because of the low number of events and wide confidence interval (RR 0.63, 95% CI 0.08 to 5.03, I
= 0%; 3 studies, 390 participants; low-quality evidence). There was no evidence to determine whether routine use of NIRS-based cerebral oxygenation monitoring causes adverse effects.
The effects of perioperative active cerebral NIRS monitoring of brain oxygenation in adults for reducing the occurrence of short-term, mild POCD are uncertain due to the low quality of the evidence. There is uncertainty as to whether active cerebral NIRS monitoring has an important effect on postoperative stroke, delirium or death because of the low number of events and wide confidence intervals. The conclusions of this review may change when the eight ongoing studies are published and the 12 studies awaiting assessment are classified. More RCTs performed in the paediatric population and high-risk patients undergoing non-cardiac surgery (e.g. neurosurgery, carotid endarterectomy and other surgery) are needed.
Abstract A 37-year-old man with nonischemic 4-chamber dilated cardiomyopathy and low-output cardiac failure (estimated ejection fraction of 10%) underwent awake craniotomy for a low-grade ...oligodendroglioma resection under monitored anesthesia care. The cerebrovascular and cardiovascular physiologic challenges and our management of this patient are discussed.
With the rise of big data, the quality of datasets has become a crucial factor affecting the performance of machine learning models. High-quality datasets are essential for the realization of data ...value. This survey article summarizes the research direction of dataset quality in machine learning, including the definition of related concepts, analysis of quality issues and risks, and a review of dataset quality dimensions and metrics throughout the dataset lifecycle and a review of dataset quality metrics analyzed from a dataset lifecycle perspective and summarized in literatures. Furthermore, this article introduces a comprehensive quality evaluation process, which includes a framework for dataset quality evaluation with dimensions and metrics, computation methods for quality metrics, and assessment models. These studies provide valuable guidance for evaluating dataset quality in the field of machine learning, which can help improve the accuracy, efficiency, and generalization ability of machine learning models, and promote the development and application of artificial intelligence technology.
The optimal oxygenation in mechanically ventilated critically ill patients remains unclear.
We performed a systematic review of randomised controlled trials (RCTs) with the aim to classify ...oxygenation goals and investigate their relative effectiveness. RCTs investigating different oxygenation goal-directed mechanical ventilation in critically ill adult patients were eligible for the analysis. The trinary classification classified oxygenation goals into conservative (partial pressure of arterial oxygen (
) 55-90 mmHg), moderate (
90-150 mmHg) and liberal (
>150 mmHg). The quadruple classification further divided the conservative goal from the trinary classification into far-conservative (
55-70 mmHg) and conservative (
70-90 mmHg) goals. The primary outcome was 30-day mortality. The secondary outcomes included intensive care unit, hospital and 90-day mortalities. The effectiveness was estimated by the relative risk and 95% credible interval (CrI) using network meta-analysis and visualised using surface under the cumulative ranking curve (SUCRA) scores and survival curves.
We identified eight eligible studies involving 2532 patients. There were no differences between conservative and moderate goals (relative risk 1.08, 95% CrI 0.85-1.36; moderate quality), between moderate and liberal goals (relative risk 0.83, 95% CrI 0.61-1.10; low quality) or between conservative and liberal goals (relative risk 0.89, 95% CrI 0.61-1.30; low quality) based on the trinary classification. There were no differences in secondary outcomes among the different goals. The results were consistent between the trinary and quadruple classifications. The SUCRA scores and survival curves suggested that the moderate goal in the trinary and quadruple classifications and the conservative goal in the quadruple classification may be superior to the liberal and far-conservative goals.
Different oxygenation goals do not lead to different mortalities in mechanically ventilated critically ill patients. The potential superiority of maintaining
in the range 70-150 mmHg remains to be validated.
Purpose
During anesthesia, maneuvers which cause the least disturbance of cerebral oxygenation with the greatest decrease in intracranial pressure would be most beneficial to patients with ...intracranial hypertension. Both head-up tilt (HUT) and hyperventilation are used to decrease brain bulk, and both may be associated with decreases in cerebral oxygenation. In this observational study, our null hypothesis was that the impact of HUT and hyperventilation on cerebral tissue oxygen saturation (SctO
2
) and cerebral blood volume (CBV) are comparable.
Methods
Surgical patients without neurological disease were anesthetized with propofol-remifentanil. Before the start of surgery, frequency-domain near-infrared spectroscopy was used to measure SctO
2
and CBV at the supine position, at the 30° head-up and head-down positions, as well as during hypoventilation and hyperventilation.
Results
Thirty-three patients were studied. Both HUT and hyperventilation induced small decreases in SctO
2
3.5 (2.6)%;
P
< 0.001 and 3.0 (1.8)%;
P
< 0.001, respectively and in CBV 0.05 (0.07) mL·100 g
−1
;
P
< 0.001 and 0.06 (0.05) mL·100 g
−1
;
P
< 0.001, respectively. There were no differences between HUT to 30° and hyperventilation to an end-tidal carbon dioxide (ETCO
2
) of 25 mmHg (from 45 mmHg) in both SctO
2
(
P
= 0.3) and CBV (
P
= 0.4).
Discussion
The small but statistically significant decreases in both SctO
2
and CBV caused by HUT and hyperventilation are comparable. There was no correlation between the decreases in SctO
2
and CBV and the decreases in blood pressure and cardiac output during head-up and head-down tilts. However, the decreases in both SctO
2
and CBV correlate with the decreases in ETCO
2
during ventilation adjustment.
Abstract The quality and standardized training and certification of young physicians is key to the quality of health care in the future. In contrast to the American system, there is no nationwide and ...standardized oral examination in the training and certification process for anesthesiologists in China. The adoptability of the American anesthesia oral examination in China, as well as potential roadblocks, has not been specifically discussed. In this commentary, we share our experience of introducing the American oral examination to an audience of Chinese anesthesiologists and propose a pragmatic approach for adopting the anesthesia oral examination in China. This initiative has the potential to reform the current anesthesia training and certification process and improve the quality of anesthetic care in China.
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