Infectious complications following regional anesthesia: a narrative review and contemporary estimates of risk.

INTRODUCTION: Infectious complications following regional anesthesia (RA) while rare, can be devastating. The objective of this review was to estimate the risk of infectious complications following central neuraxial blocks (CNB) such as epidural anesthesia (EA), spinal anesthesia (SA) and combined spinal epidural (CSE), and peripheral nerve blocks (PNB). MATERIALS AND METHODS: A literature search was conducted in PubMed, Embase and Cochrane databases to identify reference studies reporting infectious complications in the context of RA subtypes. Both prospective and retrospective studies providing incidence of infectious complications were included for review to provide pooled estimates (with 95% CI). Additionally, we explored incidences specifically associated with spinal anesthesia, incidences of central nervous system (CNS) infections and, the incidences of overall and CNS infections following CNB in obstetric population. RESULTS: The pooled estimate of overall infectious complications following all CNB was 9/100 000 (95% CI: 5, 13/100 000). CNS infections following all CNB was estimated to be 2/100 000 (95% CI: 1, 3/100 000) and even rarer following SA (1/100 000 (95% CI: 1, 2/100 000)). Obstetric population had a lower rate of overall (1/100 000 (95% CI: 1, 3/100 000)) and CNS infections (4 per million (95% CI: 0.3, 1/100 000)) following all CNB. For PNB catheters, the reported rate of infectious complications was 1.8% (95% CI: 1.2, 2.5/100). DISCUSSION: Our review suggests that the risk of overall infectious complications following neuraxial anesthesia is very rare and the rate of CNS infections is even rarer. The infectious complications following PNB catheters seems significantly higher compared with CNB. Standardizing nomenclature and better reporting methodologies are needed for the better estimation of the infectious complications.

Preoperative Cognitive Abnormality, Intraoperative Electroencephalogram Suppression, and Postoperative Delirium: A Mediation Analysis.

BACKGROUND: Postoperative delirium is a common complication that hinders recovery after surgery. Intraoperative electroencephalogram suppression has been linked to postoperative delirium, but it is unknown if this relationship is causal or if electroencephalogram suppression is merely a marker of underlying cognitive abnormalities. The hypothesis of this study was that intraoperative electroencephalogram suppression mediates a nonzero portion of the effect between preoperative abnormal cognition and postoperative delirium. METHODS: This is a prespecified secondary analysis of the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) randomized trial, which enrolled patients age 60 yr or older undergoing surgery with general anesthesia at a single academic medical center between January 2015 and May 2018. Patients were randomized to electroencephalogram-guided anesthesia or usual care. Preoperative abnormal cognition was defined as a composite of previous delirium, Short Blessed Test cognitive score greater than 4 points, or Eight Item Interview to Differentiate Aging and Dementia score greater than 1 point. Duration of intraoperative electroencephalogram suppression was defined as number of minutes with suppression ratio greater than 1%. Postoperative delirium was detected via Confusion Assessment Method or chart review on postoperative days 1 to 5. RESULTS: Among 1,113 patients, 430 patients showed evidence of preoperative abnormal cognition. These patients had an increased incidence of postoperative delirium (151 of 430 [35%] vs.123 of 683 [18%], P < 0.001). Of this 17.2% total effect size (99.5% CI, 9.3 to 25.1%), an absolute 2.4% (99.5% CI, 0.6 to 4.8%) was an indirect effect mediated by electroencephalogram suppression, while an absolute 14.8% (99.5% CI, 7.2 to 22.5%) was a direct effect of preoperative abnormal cognition. Randomization to electroencephalogram-guided anesthesia did not change the mediated effect size (P = 0.078 for moderation). CONCLUSIONS: A small portion of the total effect of preoperative abnormal cognition on postoperative delirium was mediated by electroencephalogram suppression. Study precision was too low to determine if the intervention changed the mediated effect.

Omega-3 fatty acid is a potential preventive agent for recurrent colon cancer.

Increasing evidence supports the contention that many malignancies, including sporadic colorectal cancer, are driven by the self-renewing, chemotherapy-resistant cancer stem/stem-like cells (CSC/CSLC), underscoring the need for improved preventive and therapeutic strategies targeting CSCs/CSLCs. Omega-3 polyunsaturated fatty acids (ω-3 PUFA), have been reported to inhibit the growth of primary tumors, but their potential as a preventive agent for recurring cancers is unexplored. The primary objectives of this investigation are (i) to examine whether eicosapentaenoic acid (EPA; one of the ω-3 PUFA) synergizes with FuOx (5-FU+Oxaliplatin), the backbone of colon cancer chemotherapy, and (ii) whether EPA by itself or in combination with conventional chemotherapy prevents the recurrence of colon cancer via eliminating/suppressing CSCs/CSLCs. FuOx-resistant (chemoresistant; CR) colon cancer cells, highly enriched in CSCs, were used for this study. Although EPA alone was effective, combination of EPA and FuOx was more potent in (i) inhibiting cell growth, colonosphere formation, and sphere-forming frequency, (ii) increasing sphere disintegration, (iii) suppressing the growth of SCID mice xenografts of CR colon cancer cells, and (iv) decreasing proinflammatory metabolites in mice. In addition, EPA + FuOx caused a reduction in CSC/CSLC population. The growth reduction by this regimen is the result of increased apoptosis as evidenced by PARP cleavage. Furthermore, increased pPTEN, decreased pAkt, normalization of ß-catenin expression, localization, and transcriptional activity by EPA suggests a role for the PTEN-Akt axis and Wnt signaling in regulating this process. Our data suggest that EPA by itself or in combination with FuOx could be an effective preventive strategy for recurring colorectal cancer.