Height restoration and sustainability using bilateral vertebral augmentation systems for vertebral compression fractures: a cadaveric study.

BACKGROUND CONTEXT: The treatment of vertebral compression fractures using percutaneous augmentation is an effective method to reduce pain and decrease mortality rates. Surgical methods include vertebroplasty, kyphoplasty, and vertebral augmentation with implants. A previous study suggested that a titanium implantable vertebral augmentation device (TIVAD) produced superior height restoration compared to balloon kyphoplasty (BKP) but was based on a less clinically relevant biomechanical model. Moreover, the introduction of high pressure balloons and directional instruments may further aid in restoring height. PURPOSE: The objective was to evaluate three procedures (BKP, BKP w/ Kyphon Assist (KA; directional instruments), and TIVAD) used for percutaneous augmentation of vertebral fractures with respect to height restoration and sustainability post-operatively. STUDY DESIGN/SETTING: This is an in vitro cadaver study performed in a laboratory setting. METHODS: Five osteoporotic female human cadaver thoracolumbar spines (age: 63-77 years, T-score: -2.5 to -3.5, levels: T7-S1) were scanned using computed tomography and dissected into 30 two-functional spine units (2FSUs). Vertebral wedge compression fractures were created by reducing the anterior height of the vertebrae by 25% and holding the maximum displacement for 15 minutes. Post-fracture, surgery was performed on each 2FSU with a constant 100 N load. Surgeries included BKP, BKP w/ KA, or TIVAD (n=10 per treatment group). Post-surgery, cyclic loading was performed on each 2FSU for 10,000 cycles at 600 N (walking), followed by 5,000 cycles at 850 N (standing up/sitting down), and 5,000 cycles at 1250 N (lifting a 5-10kg weight from the floor). Fluoroscopic images were taken and analyzed at the initial, post-fracture, post-surgery, and post-loading timepoints. Anterior, central, and posterior heights, Beck Index, and angle between endplates were assessed. RESULTS: No difference in height restoration was observed among treatment groups (p=.72). Compared to the initial height, post-surgery anterior height was 96.3±8.7% for BKP, 94.0±10.0% for BKP w/ KA, and 95.3±5.8% for TIVAD. No difference in height sustainability in response to 600 N (p=.76) and 850 N (p=.20) load levels was observed among treatment groups. However, after 1250 N loading, anterior height decreased to 93.8±6.8% of the post-surgery height for BKP, 95.9±6.4% for BKP w/ KA, and 86.0±6.6% for TIVAD (p=.02). Specifically, the mean anterior height reduction between post-surgery and post-1250 N loading timepoints was lower for BKP w/ KA compared to TIVAD (p=.02), but not when comparing BKP to TIVAD (p=.07). No difference in Beck Index or angle between endplates was observed at any timepoint among the treatment groups. CONCLUSIONS: The present study, utilizing a clinically relevant biomechanical model, demonstrated equivalent height restoration post-surgery and at relatively lower-level cyclic loading using BKP, BKP w/ KA, and TIVAD, contrary to results from a previous study. Less anterior height reduction in response to high-level cyclic loading was observed in the BKP w/ KA group compared to TIVAD. CLINICAL SIGNIFICANCE: All three treatments can restore height similarly after a vertebral compression fracture, which may lead to pain reduction and decreased mortality. BKP w/ KA may exhibit less height loss in higher-demand patients who engage in physical activities that involve increased weight resistance.

Treatment of chronic axial back pain with 60-day percutaneous medial branch PNS: Primary end point results from a prospective, multicenter study.

BACKGROUND: The objective of this prospective, multicenter study is to characterize responses to percutaneous medial branch peripheral nerve stimulation (PNS) to determine if results from earlier, smaller single-center studies and reports were generalizable when performed at a larger number and wider variety of centers in patients recalcitrant to nonsurgical treatments. MATERIALS & METHODS: Participants with chronic axial low back pain (LBP) were implanted with percutaneous PNS leads targeting the lumbar medial branch nerves for up to 60 days, after which the leads were removed. Participants were followed long-term for 12 months after the 2-month PNS treatment. Data collection is complete for visits through end of treatment with PNS (primary end point) and 6 months after lead removal (8 months after start of treatment), with some participant follow-up visits thereafter in progress. RESULTS: Clinically and statistically significant reductions in pain intensity, disability, and pain interference were reported by a majority of participants. Seventy-three percent of participants were successes for the primary end point, reporting clinically significant (≥30%) reductions in back pain intensity after the 2-month percutaneous PNS treatment (n = 54/74). Whereas prospective follow-up is ongoing, among those who had already completed the long-term follow-up visits (n = 51), reductions in pain intensity, disability, and pain interference were sustained in a majority of participants through 14 months after the start of treatment. CONCLUSION: Given the minimally invasive, nondestructive nature of percutaneous PNS and the significant benefits experienced by participants who were recalcitrant to nonsurgical treatments, percutaneous PNS may provide a promising first-line neurostimulation treatment option for patients with chronic axial back pain.

Percutaneous Peripheral Nerve Stimulation of the Medial Branch Nerves for the Treatment of Chronic Axial Back Pain in Patients After Radiofrequency Ablation.

OBJECTIVE: Lumbar radiofrequency ablation is a commonly used intervention for chronic back pain. However, the pain typically returns, and though retreatment may be successful, the procedure involves destruction of the medial branch nerves, which denervates the multifidus. Repeated procedures typically have diminishing returns, which can lead to opioid use, surgery, or implantation of permanent neuromodulation systems. The objective of this report is to demonstrate the potential use of percutaneous peripheral nerve stimulation (PNS) as a minimally invasive, nondestructive, motor-sparing alternative to repeat radiofrequency ablation and more invasive surgical procedures. DESIGN: Prospective, multicenter trial. METHODS: Individuals with a return of chronic axial pain after radiofrequency ablation underwent implantation of percutaneous PNS leads targeting the medial branch nerves. Stimulation was delivered for up to 60 days, after which the leads were removed. Participants were followed up to 5 months after the start of PNS. Outcomes included pain intensity, disability, and pain interference. RESULTS: Highly clinically significant (≥50%) reductions in average pain intensity were reported by a majority of participants (67%, n = 10/15) after 2 months with PNS, and a majority experienced clinically significant improvements in functional outcomes, as measured by disability (87%, n = 13/15) and pain interference (80%, n = 12/15). Five months after PNS, 93% (n = 14/15) reported clinically meaningful improvement in one or more outcome measures, and a majority experienced clinically meaningful improvements in all three outcomes (i.e., pain intensity, disability, and pain interference). CONCLUSIONS: Percutaneous PNS has the potential to shift the pain management paradigm by providing an effective, nondestructive, motor-sparing neuromodulation treatment.

Duloxetine for the reduction of opioid use in elective orthopedic surgery: a systematic review and meta-analysis.

Background Duloxetine is currently approved for chronic pain management; however, despite some evidence, its utility in acute, postoperative pain remains unclear Aim of the review This systematic review and meta-analysis is to determine if duloxetine 60 mg given perioperatively, is safe and effective at reducing postoperative opioid consumption and reported pain following elective orthopedic surgery. Method CINAHL, Medline, Cochrane Central Registry for Clinical Trials, Google Scholar, and Clinicaltrials.gov were searched using a predetermined search strategy from inception to January 15, 2019. Covidence.org was used to screen, select, and extract data by two independent reviewers. Individual study bias was assessed using the Cochrane Risk of Bias tool. Opioid consumption data were converted to oral morphine milligram equivalents (MME) and exported to RevMan where meta-analysis was conducted using a DerSimonian and Laird random effects model. Results Six randomized-controlled trials were included in the literature review of postoperative pain and adverse effects. Five studies were utilized for the meta-analysis of postoperative opioid consumption; totaling 314 patients. Postoperative pain analysis showed variable statistical significance with overall lower pain scores with duloxetine. Adverse effects included an increase in insomnia with duloxetine but lower rates of nausea and vomiting. Meta-analysis revealed statistically significant [mean difference (95% CI)] lower total opioid use with duloxetine postoperatively at 24 h [- 31.9 MME (- 54.22 to - 9.6), p = 0.005], 48 h [- 30.90 MME (- 59.66 to - 2.15), p = 0.04] and overall [- 31.68 MME (- 46.62 to - 16.74), p < 0.0001]. Conclusion These results suggest that adding perioperative administration duloxetine 60 mg to a multimodal analgesia regimen within the orthopedic surgery setting significantly lowers total postoperative opioid consumption and reduces pain without significant adverse effects.

Top Ten Tips Palliative Care Clinicians Should Know About Interventional Pain and Procedures.

Pain is a common symptom for patients with advanced illness. Palliative care (PC) clinicians are experts in pharmacologic and nonpharmacologic treatment of pain and other symptoms for these patients. True multimodal pain control should include consideration of interventional procedures and pumps to improve difficult-to-manage pain. This article, written by clinicians with expertise in interventional pain and PC, outlines and explains many of the adjunctive and interventional therapies that can be considered for patients with pain in the setting of serious illness. Only by understanding and considering all available options can we ensure that our patients are receiving optimal care.

Perioperative Anesthetic Techniques to Reduce Surgical Morbidity After Amputation.

Anesthetic modalities to mitigate the development of phantom limb pain have not been standardized into an evidence-based, multimodal anesthesia protocol to promote improved patient outcomes. This quality improvement project involved the implementation of a lower extremity, amputation-specific anesthesia protocol. In the postimplementation group, 94 patients were anesthetized for their amputation using an Amputation Improved Recovery Enhanced Recovery After Surgery (ERAS) protocol. Patient outcomes before and after protocol implementation were compared. The rate of continuous peripheral nerve block placement was higher in the postimplementation group (37.2%) than the preimplementation group (29.6%, P = .337). The 2 groups did not differ on average pain scores and morphine equivalent consumption rates per patient during hospitalization. The postimplementation group had significantly lower mean pain scores during the first 24 hours after amputation (P = .046); fewer postoperative complications (P = .001), amputation revisions (P = .003), 30-day hospital readmissions (P = .049), and readmissions related to amputation surgery (P = .019); and higher rates of early phantom limb pain that resolved during hospitalization (P = .012). Use of a standardized anesthetic protocol designed for patients undergoing amputation improved patient outcomes. Trials of this protocol elsewhere may contribute to improved recovery for patients undergoing amputations.

Occurrence of Symptomatic Hypotension in Patients Undergoing Breast Free Flaps: Is Enhanced Recovery after Surgery to Blame?

BACKGROUND: Enhanced recovery after surgery (ERAS) initiatives improve postoperative function and expedite recovery, leading to a decrease in length of stay. The authors noted a high rate of postoperative symptomatic hypotension in patients undergoing abdominal free flap breast reconstruction and wished to explore this observation. METHODS: Subjects undergoing abdominal free flap breast reconstruction at the authors' institution from 2013 to 2017 were identified. The ERAS protocol was initiated in 2015 at the authors' hospital; thus, 99 patients underwent traditional management and 138 patients underwent ERAS management. Demographics and perioperative data were collected and analyzed. Postoperative symptomatic hypotension was defined as mean arterial pressure below 80 percent of baseline with symptoms requiring evaluation. RESULTS: A significantly higher rate of postoperative symptomatic hypotension was observed in the ERAS cohort compared with the traditional management cohort (4 percent versus 22 percent; p < 0.0001). Patients in the ERAS cohort received significantly less intraoperative intravenous fluid (4467 ml versus 3505 ml; p < 0.0001) and had a significantly increased amount of intraoperative time spent with low blood pressure (22 percent versus 32 percent; p =0.002). Postoperatively, the ERAS cohort had significantly lower heart rate (77 beats per minute versus 88 beats per minute; p < 0.0001) and mean arterial pressure (71 mmHg versus 78 mmHg; p < 0.0001), with no difference in urine output or adverse events. CONCLUSIONS: The authors report that ERAS implementation in abdominal free flap breast reconstruction may result in a unique physiologic state with low mean arterial pressure, low heart rate, and normal urine output, resulting in postoperative symptomatic hypotension. Awareness of this early postoperative finding can help better direct fluid resuscitation and prevent episodes of symptomatic hypotension. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Undersedation During Total Hip Arthroplasty Reduction Results in Worse Patient Outcomes.

BACKGROUND: Total hip arthroplasty (THA) dislocation is a common reason for presentation to the emergency department (ED) postoperatively. Prior literature has shown that propofol conscious sedation provides the fewest complications and the shortest time to reduction. However, we are aware of no prior reports exploring sedative dosing regimens. We hypothesized that "undersedated" patients would have worse outcomes compared to appropriately sedated patients based on dose. METHODS: This is a retrospective review of isolated propofol conscious sedation performed in the ED for closed reduction of THA dislocations from 2013 to 2019. Prior authors have used at least 0.5 mg/kg/dose for sedation with propofol. Therefore, to allow a 10% rounding error, a dose of less than 0.45 mg/kg/dose was considered undersedated. Demographic information was collected and outcomes including sedation time, number of doses, complications, and successful reductions were analyzed in univariable and multivariable analyses. RESULTS: A total of 79 THAs were included for analysis with mean age 65.5 (16.2) years and weight 84.1 (21.3) kg. Thirty-seven (46.8%) patients had undergone revision surgery and 44 (55.7%) previously had a dislocation. A total of 39 patients were undersedated. There was no significant difference in demographics or arthroplasty-specific variables between undersedated and "protocol" sedation patients. In multivariable analysis, undersedated patients had significantly longer sedation time (P = .020), more re-doses (by mean 3 doses; P < .001), and greater total dose (P = .002). These patients were also more likely to have failed ED closed reduction (10.3% vs 0.0%; P = .038). One complication of a skin tear from countertraction was observed in an undersedated patient. CONCLUSION: Historically, conscious sedation for THA dislocations has been the responsibility of the emergency room clinician. In consideration of our outcomes, we advocate for a multidisciplinary team to create a sedation protocol, emphasizing the need to maintain a dosing regimen of 0.5 mg/kg/dose to improve the care of THA patients.

Paradox of age: older patients receive higher age-adjusted minimum alveolar concentration fractions of volatile anaesthetics yet display higher bispectral index values.

BACKGROUND: Minimum alveolar concentration (MAC) and MAC-awake decrease with age. We hypothesised that, in clinical practice, (i) end-tidal MAC fraction in older patients would decline by less than the predicted age-dependent MAC decrease (i.e. older patients would receive relatively excessive anaesthetic concentrations), and (ii) bispectral index (BIS) values would therefore be lower in older patients. METHODS: We examined the relationship between end-tidal MAC fraction, BIS values, and age in 4699 patients > 30 yr in age at a single centre using unadjusted local regression (locally estimated scatterplot smoothing), Spearman's correlation, stratification, and robust univariable and multivariable linear regression. RESULTS: The end-tidal MAC fraction in older patients declined by 3.01% per decade (95% confidence interval [CI]: 2.56-3.45; P<0.001), less than the 6.47% MAC decrease per decade that we found in a meta-regression analysis of published studies of age-dependent changes in MAC (P<0.001), and less than the age-dependent decrease in MAC-awake. The BIS values correlated positively with age (ρ=0.15; 95% CI: 0.12-0.17; P<0.001), and inversely with the age-adjusted end-tidal MAC (aaMAC) fraction (ρ= -0.13; 95% CI: -0.16, -0.11; P<0.001). CONCLUSIONS: The age-dependent decline in end-tidal MAC fraction delivered in clinical practice at our institution was less than the age-dependent percentage decrease in MAC and MAC-awake determined from published studies. Despite receiving higher aaMAC fractions, older patients paradoxically showed higher BIS values. This most likely suggests that the BIS algorithm is inaccurate in older adults.

Preoperative Blood Management Strategy for Elective Hip and Knee Arthroplasty.

To improve quality and outcomes, a preoperative anemia clinic (PAC) was established to screen, evaluate, and manage preoperative anemia. A retrospective review of primary and revision hip and knee arthroplasty patients from August 2013 to September 2017 was conducted. Patients at "high risk" for transfusion were referred to PAC for treatment with iron, erythropoietin, or both based on anemia type. Preoperative anemia clinic referred patients were compared with a 1:3 historic propensity-matched control set of patients to help determine impact of PAC. Forty PAC patients were compared with 120 control patients. Among PAC patients, 26 (63.41%) received iron only, 3 (7.32%) received erythropoietin (EPO) only, and 12 (29.27%) received both. Preoperative hemoglobin significantly increased in the treatment group (median [interquartile range] 10.9 g/dl [10.3-11.2] vs. 12.0 g/dl [11.2-12.7]; p < .001). Four PAC patients (10.00%) received red blood cell transfusions compared with 29 (24.17%) from matched controls (p = .055). In addition, the PAC cohort had higher postoperative nadir hemoglobin levels (mean [SD] 9.7 g/dl [1.31] vs. 8.7 g/dl [1.25]; p < .001). High-risk patients appropriately treated with iron and/or EPO before surgery demonstrate a significant increase in preoperative hemoglobin, trend toward decrease perioperative transfusion, and increased hemoglobin levels postoperatively compared with matched controls.

Human B-1 Cells and B-1 Cell Antibodies Change With Advancing Age.

Age-related deficits in the immune system have been associated with an increased incidence of infections, autoimmune diseases, and cancer. Human B cell populations change quantitatively and qualitatively in the elderly. However, the function of human B-1 cells, which play critical anti-microbial and housekeeping roles, have not been studied in the older age population. In the present work, we analyzed how the frequency, function and repertoire of human peripheral blood B-1 cells (CD19+CD20+CD27+CD38low/intCD43+) change with age. Our results show that not only the percentage of B-1 cells but also their ability to spontaneously secrete IgM decreased with age. Further, expression levels of the transcription factors XBP-1 and Blimp-1 were significantly lower, while PAX-5, characteristic of non-secreting B cells, was significantly higher, in healthy donors over 65 years (old) as compared to healthy donors between 20 and 45 years (young). To further characterize the B-1 cell population in older individuals, we performed single cell sequencing analysis of IgM heavy chains from healthy young and old donors. We found reduced repertoire diversity of IgM antibodies in B-1 cells from older donors as well as differences in usage of certain VH and DH specific genes, as compared to younger. Overall, our results show impairment of the human B-1 cell population with advancing age, which might impact the quality of life and onset of disease within the elderly population.

A Novel Risk Calculator Predicts 90-Day Readmission Following Total Joint Arthroplasty.

BACKGROUND: A reliable prediction tool for 90-day adverse events not only would provide patients with valuable estimates of their individual risk perioperatively, but would also give health-care systems a method to enable them to anticipate and potentially mitigate postoperative complications. Predictive accuracy, however, has been challenging to achieve. We hypothesized that a broad range of patient and procedure characteristics could adequately predict 90-day readmission after total joint arthroplasty (TJA). METHODS: The electronic medical records on 10,155 primary unilateral total hip (4,585, 45%) and knee (5,570, 55%) arthroplasties performed at a single institution from June 2013 to January 2018 were retrospectively reviewed. In addition to 90-day readmission status, >50 candidate predictor variables were extracted from these records with use of structured query language (SQL). These variables included a wide variety of preoperative demographic/social factors, intraoperative metrics, postoperative laboratory results, and the 30 standardized Elixhauser comorbidity variables. The patient cohort was randomly divided into derivation (80%) and validation (20%) cohorts, and backward stepwise elimination identified important factors for subsequent inclusion in a multivariable logistic regression model. RESULTS: Overall, subsequent 90-day readmission was recorded for 503 cases (5.0%), and parameter selection identified 17 variables for inclusion in a multivariable logistic regression model on the basis of their predictive ability. These included 5 preoperative parameters (American Society of Anesthesiologists [ASA] score, age, operatively treated joint, insurance type, and smoking status), duration of surgery, 2 postoperative laboratory results (hemoglobin and blood-urea-nitrogen [BUN] level), and 9 Elixhauser comorbidities. The regression model demonstrated adequate predictive discrimination for 90-day readmission after TJA (area under the curve [AUC]: 0.7047) and was incorporated into static and dynamic nomograms for interactive visualization of patient risk in a clinical or administrative setting. CONCLUSIONS: A novel risk calculator incorporating a broad range of patient factors adequately predicts the likelihood of 90-day readmission following TJA. Identifying at-risk patients will allow providers to anticipate adverse outcomes and modulate postoperative care accordingly prior to discharge. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

American Society for Enhanced Recovery (ASER) and Perioperative Quality Initiative (POQI) joint consensus statement on measurement to maintain and improve quality of enhanced recovery pathways for elective colorectal surgery.

BACKGROUND: This article sets out a framework for measurement of quality of care relevant to enhanced recovery pathways (ERPs) in elective colorectal surgery. The proposed framework is based on established measurement systems and/or theories, and provides an overview of the different approaches for improving clinical monitoring, and enhancing quality improvement or research in varied settings with different levels of available resources. METHODS: Using a structure-process-outcome framework, we make recommendations for three hierarchical tiers of data collection. DISCUSSION: Core, Quality Improvement, and Best Practice datasets are proposed. The suggested datasets incorporate patient data to describe case-mix, process measures to describe delivery of enhanced recovery and clinical outcomes. The fundamental importance of routine collection of data for the initiation, maintenance, and enhancement of enhanced recovery pathways is emphasized.

Human B-1 and B-2 B Cells Develop from Lin-CD34+CD38lo Stem Cells.

The B-1 B cell population is an important bridge between innate and adaptive immunity primarily because B-1 cells produce natural Ab. Murine B-1 and B-2 cells arise from distinct progenitors; however, in humans, in part because it has been difficult to discriminate between them phenotypically, efforts to pinpoint the developmental origins of human B-1 and B-2 cells have lagged. To characterize progenitors of human B-1 and B-2 cells, we separated cord blood and bone marrow Lin-CD34+ hematopoietic stem cells into Lin-CD34+CD38lo and Lin-CD34+CD38hi populations. We found that transplanted Lin-CD34+CD38lo cells, but not Lin-CD34+CD38hi cells, generated a CD19+ B cell population after transfer into immunodeficient NOD.Cg-Prkdcscid Il2rgtm1wjl/SxJ neonates. The emergent CD19+ B cell population was found in spleen, bone marrow, and peritoneal cavity of humanized mice and included distinct populations displaying the B-1 or the B-2 cell phenotype. Engrafted splenic B-1 cells exhibited a mature phenotype, as evidenced by low-to-intermediate expression levels of CD24 and CD38. The engrafted B-1 cell population expressed a VH-DH-JH composition similar to cord blood B-1 cells, including frequent use of VH4-34 (8 versus 10%, respectively). Among patients with hematologic malignancies who underwent hematopoietic stem cell transplantation, B-1 cells were found in the circulation as early as 8 wk posttransplantation. Altogether, our data demonstrate that human B-1 and B-2 cells develop from a Lin-CD34+CD38lo stem cell population, and engrafted B-1 cells in humanized mice exhibit an Ig-usage pattern comparable to B-1 cells in cord blood.

Associations between ASA Physical Status and postoperative mortality at 48 h: a contemporary dataset analysis compared to a historical cohort.

BACKGROUND: In this study, we examined the association between American Society of Anesthesiologists Physical Status (ASA PS) designation and 48-h mortality for both elective and emergent procedures in a large contemporary dataset (patient encounters between 2009 and 2014) and compared this association with data from a landmark study published by Vacanti et al. in 1970. METHODS: Patient history, hospital characteristics, anesthetic approach, surgical procedure, efficiency and quality indicators, and patient outcomes were prospectively collected for 732,704 consecutive patient encounters between January 1, 2009, and December 31, 2014, at 233 anesthetizing locations across 19 facilities in two US states and stored in the Quantum™ Clinical Navigation System (QCNS) database. The outcome (death within 48 h of procedure) was tabulated against ASA PS designations separately for patients with and without "E" status labels. To maintain consistency with the historical cohort from the landmark study performed by Vacanti et al. on adult men at US naval hospitals in 1970, we then created a comparison cohort in the contemporary dataset that consisted of 242,103 adult male patients (with/without E designations) undergoing elective and emergent procedures. Differences in the relationship between ASA PS and 48-h mortality in the historical and contemporary cohorts were assessed for patients undergoing elective and emergent procedures. RESULTS: As reported nearly five decades ago, we found a significant trend toward increased mortality with increasing ASA PS for patients undergoing both elective and emergent procedures in a large contemporary cohort (p < 0.0001). Additionally, the overall mortality rate at 48 h was significantly higher among patients undergoing emergent compared to elective procedures in the large contemporary cohort (1.27 versus 0.03 %, p < 0.0001). In the comparative analysis with the historical cohort that focused on adult males, we found the overall 48-h mortality rate was significantly lower among patients undergoing elective procedures in the contemporary cohort (0.05 % now versus 0.24 % in 1970, p < 0.0001) but not significantly lower among those undergoing emergent procedures (1.88 % now versus 1.22 % in 1970, p < 0.0001). CONCLUSIONS: The association between increasing ASA PS designation (1-5) and mortality within 48 h of surgery is significant for patients undergoing both elective and emergent procedures in a contemporary dataset consisting of over 700,000 patient encounters. Emergency surgery was associated with a higher risk of patient death within 48 h of surgery in this contemporary dataset. These data trends are similar to those observed nearly five decades ago in a landmark study evaluating the association between ASA PS and 48-h surgical mortality on adult men at US naval hospitals. When a comparison cohort was created from the contemporary dataset and compared to this landmark historical cohort, the absolute 48-h mortality rate was significantly lower in the contemporary cohort for elective procedures but not significantly lower for emergency procedures. The underlying implications of these findings remain to be determined.

Age-Related Decline in Natural IgM Function: Diversification and Selection of the B-1a Cell Pool with Age.

Streptococcus pneumoniae is the most common cause of pneumonia, which claims the lives of people over the age of 65 y seven times more frequently than those aged 5-49 y. B-1a cells provide immediate and essential protection from S. pneumoniae through production of natural Ig, which has minimal insertion of N-region additions added by the enzyme TdT. In experiments with SCID mice infected with S. pneumoniae, we found passive transfer of IgG-depleted serum from aged (18-24 mo old) mice had no effect whereas IgG-depleted serum from young (3 mo old) mice was protective. This suggests protective natural IgM changes with age. Using single cell PCR we found N-region addition, which is initially low in fetal-derived B-1a cell IgM developing in the absence of TdT, increased in 7- to 24-mo-old mice as compared with 3-mo-old mice. To determine the mechanism responsible for the age related change in B-1a cell IgM, we established a mixed chimera system in which mice were reconstituted with allotype-marked mature peritoneal B-1a cells and adult bone marrow cells. We demonstrated even in the presence of mature peritoneal B-1a cells, adult bone marrow contributed to the mature B-1a cell pool. More importantly, using this system we found over a 10-mo-period peritoneal B-1a cell IgM changed, showing the number of cells lacking N-region additions at both junctions fell from 49 to 29% of sequences. These results strongly suggest selection-induced skewing alters B-1a cell-derived natural Ab, which may in turn be responsible for the loss of natural IgM-mediated protection against pneumococcal infection.

Thoracic Nerve Root Entrapment by Intrathecal Catheter Coiling: Case Report and Review of the Literature.

BACKGROUND: Intrathecal catheter placement has long-term therapeutic benefits in the management of chronic, intractable pain. Despite the diverse clinical applicability and rising prevalence of implantable drug delivery systems in pain medicine, the spectrum of complications associated with intrathecal catheterization remains largely understudied and underreported in the literature. OBJECTIVE: To report a case of thoracic nerve root entrapment resulting from intrathecal catheter migration. STUDY DESIGN: Case report. SETTING: Inpatient hospital service. RESULTS/ CASE REPORT: A 60-year-old man status post implanted intrathecal (IT) catheter for intractable low back pain secondary to failed back surgery syndrome returned to the operating room for removal of IT pump trial catheter after experiencing relapse of preoperative pain and pump occlusion. Initial attempt at ambulatory removal of the catheter was aborted after the patient reported acute onset of lower extremity radiculopathic pain during the extraction. Noncontrast computed tomography (CT) subsequently revealed that the catheter had ascended and coiled around the T10 nerve root. The patient was taken back to the operating room for removal of the catheter under fluoroscopic guidance, with possible laminectomy for direct visualization. Removal was ultimately achieved with slow continuous tension, with complete resolution of the patient's new radicular symptoms. LIMITATIONS: This report describes a single case report. CONCLUSION: This case demonstrates that any existing loops in the intrathecal catheter during initial implantation should be immediately re-addressed, as they can precipitate nerve root entrapment and irritation. Reduction of the loop or extrication of the catheter should be attempted under continuous fluoroscopic guidance to prevent further neurosurgical morbidity.