Patterns and Persistence of Perioperative Plasma and Cerebrospinal Fluid Neuroinflammatory Protein Biomarkers After Elective Orthopedic Surgery Using SOMAscan

BACKGROUND

The neuroinflammatory response to surgery can be characterized by peripheral acute plasma protein changes in blood, but corresponding, persisting alterations in cerebrospinal fluid (CSF) proteins remain mostly unknown. Using the SOMAscan assay, we define acute and longer-term proteome changes associated with surgery in plasma and CSF. We hypothesized that biological pathways identified by these proteins would be in the categories of neuroinflammation and neuronal function and define neuroinflammatory proteome changes associated with surgery in older patients.

METHODS

SOMAscan analyzed 1305 proteins in blood plasma (n = 14) and CSF (n = 15) samples from older patients enrolled in the Role of Inflammation after Surgery for Elders (RISE) study undergoing elective hip and knee replacement surgery with spinal anesthesia. Systems biology analysis identified biological pathways enriched among the surgery-associated differentially expressed proteins in plasma and CSF.

RESULTS

Comparison of postoperative day 1 (POD1) to preoperative (PREOP) plasma protein levels identified 343 proteins with postsurgical changes ( P < .05; absolute value of the fold change [|FC|] > 1.2). Comparing postoperative 1-month (PO1MO) plasma and CSF with PREOP identified 67 proteins in plasma and 79 proteins in CSF with altered levels ( P < .05; |FC| > 1.2). In plasma, 21 proteins, primarily linked to immune response and inflammation, were similarly changed at POD1 and PO1MO. Comparison of plasma to CSF at PO1MO identified 8 shared proteins. Comparison of plasma at POD1 to CSF at PO1MO identified a larger number, 15 proteins in common, most of which are regulated by interleukin-6 (IL-6) or transforming growth factor beta-1 (TGFB1) and linked to the inflammatory response. Of the 79 CSF PO1MO-specific proteins, many are involved in neuronal function and neuroinflammation.

CONCLUSIONS

SOMAscan can characterize both short- and long-term surgery-induced protein alterations in plasma and CSF. Acute plasma protein changes at POD1 parallel changes in PO1MO CSF and suggest 15 potential biomarkers for longer-term neuroinflammation that warrant further investigation.

Comprehensive Ultrasound Course for Special Operations Combat and Tactical Medics

BACKGROUND

Advances in ultrasound technology with enhanced portability and high-quality imaging has led to a surge in its use on the battlefield by nonphysician providers. However, there is a consistent need for comprehensive and standardized ultrasound training to improve ultrasound knowledge, manual skills, and workflow understanding of nonphysician providers.

MATERIALS AND METHODS

Our team designed a multimodal ultrasound course to improve ultrasound knowledge, manual skills, and workflow understanding of nine Special Operations combat medics and Special Operations tactical medics. The course was based on a flipped classroom model with a total time of 43 hours, consisting of an online component followed by live lectures and hands-on workshops. The effectiveness of the course was determined using a knowledge exam, expert ratings of manual skills using a global rating scale, and an objective structured clinical skills examination (OSCE).

RESULTS

The average knowledge exam score of the medics increased from pre-course (56% ± 6.8%) to post-course (80% ± 5.0%, p < .001). Based on expert ratings, their manual skills improved from baseline to day 4 of the course for image finding (p = .007), image optimization (p = .008), image acquisition speed (p = .008), final image quality (p = .008), and global assessment (p = .008). Their average score at every OSCE station was > 91%.

CONCLUSION

A comprehensive multimodal training program can be used to improve military medics' ultrasound knowledge, manual skills, and workflow understanding for various applications of ultrasound. Further research is required to develop a reliable, sustainable course.

Plasma and cerebrospinal fluid inflammation and the blood-brain barrier in older surgical patients: the Role of Inflammation after Surgery for Elders (RISE) study

Background

Our understanding of the relationship between plasma and cerebrospinal fluid (CSF) remains limited, which poses an obstacle to the identification of blood-based markers of neuroinflammatory disorders. To better understand the relationship between peripheral and central nervous system (CNS) markers of inflammation before and after surgery, we aimed to examine whether surgery compromises the blood-brain barrier (BBB), evaluate postoperative changes in inflammatory markers, and assess the correlations between plasma and CSF levels of inflammation.

Methods

We examined the Role of Inflammation after Surgery for Elders (RISE) study of adults aged ≥ 65 who underwent elective hip or knee surgery under spinal anesthesia who had plasma and CSF samples collected at baseline and postoperative 1 month (PO1MO) (n = 29). Plasma and CSF levels of three inflammatory markers previously identified as increasing after surgery were measured using enzyme-linked immunosorbent assay: interleukin-6 (IL-6), C-reactive protein (CRP), and chitinase 3-like protein (also known as YKL-40). The integrity of the BBB was computed as the ratio of CSF/plasma albumin levels (Qalb). Mean Qalb and levels of inflammation were compared between baseline and PO1MO. Spearman correlation coefficients were used to determine the correlation between biofluids.

Results

Mean Qalb did not change between baseline and PO1MO. Mean plasma and CSF levels of CRP and plasma levels of YKL-40 and IL-6 were higher on PO1MO relative to baseline, with a disproportionally higher increase in CRP CSF levels relative to plasma levels (CRP tripled in CSF vs. increased 10% in plasma). Significant plasma-CSF correlations for CRP (baseline r = 0.70 and PO1MO r = 0.89, p < .01 for both) and IL-6 (PO1MO r = 0.48, p < .01) were observed, with higher correlations on PO1MO compared with baseline.

Conclusions

In this elective surgical sample of older adults, BBB integrity was similar between baseline and PO1MO, plasma-CSF correlations were observed for CRP and IL-6, plasma levels of all three markers (CRP, IL-6, and YKL-40) increased from PREOP to PO1MO, and CSF levels of only CRP increased between the two time points. Our identification of potential promising plasma markers of inflammation in the CNS may facilitate the early identification of patients at greatest risk for neuroinflammation and its associated adverse cognitive outcomes.

The Role of Inflammation after Surgery for Elders (RISE) study: Study design, procedures, and cohort profile

Introduction

The Role of Inflammation after Surgery for Elders study correlates novel inflammatory markers measured in blood, cerebrospinal fluid (CSF) assays, and [¹¹C]-PBR28 positron-emission tomography imaging.

Methods

This study involved a prospective cohort design with patients who underwent elective hip and knee arthroplasty under spinal anesthesia. Sixty-five adults participated with their family members. Inflammatory biomarker assays were measured preoperatively on day 1 and postoperatively at one month.

Results

On average, participants were 75 years old, and 72% were female. 54% underwent total knee arthroplasty, and 46% underwent total hip arthroplasty. The mean Modified Mini-Mental State (3MS) Examination score was 89.3; four patients (6%) scored ≤77 points. Plasma assays were completed in 63 (97%) participants, cerebrospinal fluid assays in 61 (94%), and PET imaging in 44 (68%).

Discussion

This complex study presents an innovative effort to correlate peripheral and central inflammatory biomarkers before and after major surgery in older adults. Strengths include collecting concurrent blood, cerebrospinal fluid, and positron-emission tomography with detailed clinical characterization of delirium, cognition, and functional status.

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We describe the methodology of the Role of Inflammation after Surgery for Elders Study.

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This is a prospective cohort of elective hip/knee arthroplasty patients 70 years or older.

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We examine inflammation in blood, cerebrospinal fluid and positron emission tomography.

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We collect novel biomarkers preoperatively and one-month postoperatively.

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There is clinical characterization of delirium, cognition and functional status.

Postoperative Delirium and Postoperative Cognitive Dysfunction: Overlap and Divergence

BACKGROUND

Postoperative delirium and postoperative cognitive dysfunction share risk factors and may co-occur, but their relationship is not well established. The primary goals of this study were to describe the prevalence of postoperative cognitive dysfunction and to investigate its association with in-hospital delirium. The authors hypothesized that delirium would be a significant risk factor for postoperative cognitive dysfunction during follow-up.

METHODS

This study used data from an observational study of cognitive outcomes after major noncardiac surgery, the Successful Aging after Elective Surgery study. Postoperative delirium was evaluated each hospital day with confusion assessment method-based interviews supplemented by chart reviews. Postoperative cognitive dysfunction was determined using methods adapted from the International Study of Postoperative Cognitive Dysfunction. Associations between delirium and postoperative cognitive dysfunction were examined at 1, 2, and 6 months.

RESULTS

One hundred thirty-four of 560 participants (24%) developed delirium during hospitalization. Slightly fewer than half (47%, 256 of 548) met the International Study of Postoperative Cognitive Dysfunction-defined threshold for postoperative cognitive dysfunction at 1 month, but this proportion decreased at 2 months (23%, 123 of 536) and 6 months (16%, 85 of 528). At each follow-up, the level of agreement between delirium and postoperative cognitive dysfunction was poor (kappa less than .08) and correlations were small (r less than .16). The relative risk of postoperative cognitive dysfunction was significantly elevated for patients with a history of postoperative delirium at 1 month (relative risk = 1.34; 95% CI, 1.07-1.67), but not 2 months (relative risk = 1.08; 95% CI, 0.72-1.64), or 6 months (relative risk = 1.21; 95% CI, 0.71-2.09).

CONCLUSIONS

Delirium significantly increased the risk of postoperative cognitive dysfunction in the first postoperative month; this relationship did not hold in longer-term follow-up. At each evaluation, postoperative cognitive dysfunction was more common among patients without delirium. Postoperative delirium and postoperative cognitive dysfunction may be distinct manifestations of perioperative neurocognitive deficits.

Chloroprocaine may not affect epidural morphine for postcesarean delivery analgesia

STUDY OBJECTIVE

The purpose of this study is to assess the independent effect of epidural chloroprocaine on morphine used for pain relief after cesarean delivery.

DESIGN

We used a randomized, double blind, placebo-controlled trial.

SETTING

The study took place at the labor and delivery ward of an academic medical center.

PATIENTS

Forty pregnant women undergoing elective cesarean delivery under spinal-epidural anesthesia.

INTERVENTIONS

Patients were randomized to receive either 150 mg of 3% chloroprocaine or placebo, followed by 3 mg of epidural morphine.

MEASUREMENTS

The primary outcome for this investigation was the duration of pain relief after morphine administration, defined as the time at first use of supplemental opioids for analgesia. Secondary outcomes included pain scores, blood pressure, heart rate, respiratory rate, anesthetic sensory level, nausea and vomiting, pruritus, supplemental use of nonsteroidal anti-inflammatory medications, and satisfaction.

MAIN RESULTS

The groups were similar in demographics and duration of spinal anesthesia. Using Kaplan-Meier survival analysis of the duration of morphine analgesia, we found no difference between the groups (chloroprocaine, 1191 minutes, vs placebo, 1267 minutes, P = 0.52). There was no difference in pain scores or the need for supplemental analgesics. Side effects of epidural morphine were similar between the groups.

CONCLUSIONS

We found that epidural chloroprocaine did not reduce the duration or effectiveness of postoperative analgesia from epidural morphine.

An ion-selective microelectrode for bile salts

The development of a prototype ion-selective microelectrode for bile salts is described. The microelectrodes demonstrated Nernstian response (59 +/- 10 mV dec-1) with sodium deoxycholate in Tris (0.2 M, pH 9.0, 15-30 degrees C), HEPES (0.13 M, pH 7.5), and bicarbonate buffers (0.1 M, pH 7.5) (25 +/- 0.1 degrees C) were stable for several days, and the responses were highly reproducible. The microelectrodes were selective for bile salts over the physiologically important inorganic anions, bicarbonate and chloride. The response to sodium cholate (42 mV dec-1) was consistently lower than the ideal response (59 mV dec-1). This ion-selective microelectrode may show promise as a useful tool for the determination of intracellular bile salt activity.