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OBJECTIVE: The objective of this study was to investigate variations across hospitals in infection rates and associated costs, the latter reflected in 90-day Medicare payments. Despite high rates and expenditures of healthcare-associated infections associated with durable ventricular assist device implant, few studies have examined inter-hospital variation and associated costs. METHODS: Clinical data on 8688 patients who received primary durable ventricular assist devices from July 2008 to July 2017 from The Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) hospitals (n=120) were merged with post-implant 90-day Medicare claims. Terciles of hospital-specific, risk-adjusted infection rates per 100 patient-months were estimated using Intermacs and associated with Medicare payments (among 5440 Medicare beneficiaries). Primary outcomes included infections within 90 days of implant and Medicare payments. RESULTS: There were 3982 infections identified among 27.8% (2,417/8,688) of patients developing an infection. The median (25(th), 75(th) percentile) adjusted incidence of infections (per 100 patient-months) across hospitals was 14.3 (9.3, 19.5) and varied by hospital (range 0.0 – 35.6). Total Medicare payments from implant to 90-days were 9.0% (absolute difference: $13,652) greater in high versus low infection tercile hospitals, p

Objective Infections are among the most common complications in recipients of durable left ventricular assist devices (LVAD). However, existing studies examining infections in LVAD recipients are limited is size and design. Comprehensive, systematic reviews of all types of infections occurring among recipients of contemporary LVADs have not been conducted. The goal of this scoping review was to synthesize all available evidence related to rates of infections (including location and types) in LVAD recipients. Methods In February 2019, 4,581 published studies were identified through searching five bibliographic databases: PubMed, Scopus, EMBASE, CINAHL and Web of Science Core Collection. Inclusion criteria required reporting of infectious complications among LVAD recipients receiving contemporary (HeartMate II, HeartMate 3 and HeartWare HVAD) LVADs. Study key characteristics were extracted by 2 independent reviewers and current literature described narratively. All analyses took place between Feb 2019 and Jan 2021. Results A total of 132 studies met inclusion criteria. Most studies were observational (n=118; 89.4%), single-center (n=93, 70.4%) and from the U.S. (n=88; 66.7%). Only 48 (36.3%) studies used the standardized International Society for Heart and Lung Transplantation (ISHLT) definition for reporting infections. Only 35 (26.5%) studies reported age, gender and racial distribution of their study population. Driveline infections were the most commonly reported infection type. Conclusions Most studies did not utilize standardized infection definitions or provide complete information on infection locations and types. In order to further advance the scientific rigor, published studies should (i) use standardized definitions for reporting infections and (ii) stratify rates by infection location and type.

Background Familiarity among cardiac surgery team members may be an important contributor to better outcomes and thus serve as a target for enhancing outcomes. Methods Adult cardiac surgical procedures (n = 4,445) involving intraoperative providers were evaluated at a tertiary hospital between 2016 and 2020. Team familiarity (mean of prior cardiac surgeries performed by participating surgeon/nonsurgeon pairs within 2 years before the operation) were regressed on cardiopulmonary bypass duration (primary—an intraoperative measure of care efficiency) and postoperative complication outcomes (major morbidity, mortality), adjusting for provider experience, surgeon 2-year case volume before the surgery, case start time, weekday, and perioperative risk factors. The relationship between team familiarity and outcomes was assessed across predicted risk strata. Results Median (interquartile range) cardiopulmonary bypass duration was 132 (91–192) minutes, and 698 (15.7%) patients developed major postoperative morbidity. The relationship between team familiarity and cardiopulmonary bypass duration significantly differed across predicted risk strata (P = .0001). High (relative to low) team familiarity was associated with reduced cardiopulmonary bypass duration for medium-risk (–24 minutes) and high-risk (–27 minutes) patients. Increasing team familiarity was not significantly associated with the odds of major morbidity and mortality. Conclusion Team familiarity, which was predictive of improved intraoperative efficiency without compromising major postoperative outcomes, may serve as a novel quality improvement target in the setting of cardiac surgery.

OBJECTIVE: Despite advances in echocardiography and hemodynamic monitoring, limited progress has been made to effectively quantify left ventricular function during cardiac surgery. Traditional measures including left ventricular ejection fraction (LVEF) and cardiac index remain dependent on loading conditions; more complex measures remain impractical in a dynamic surgical setting. However, the Smith-Madigan Inotropy Index (SMII) and potential-to-kinetic energy ratio (PKR) offer promise as measures calculable during cardiac surgery and potentially predictive of outcomes. Using echocardiographic and hemodynamic monitoring data, we aimed to calculate SMII and PKR values after cardiopulmonary bypass, and understand associations with postoperative outcomes, adjusting for previously identified risk factors. DESIGN: Observational cohort study. SETTING: Tertiary care academic hospital. PATIENTS: 189 elective adult cardiac surgical procedures from 2015 to 2016. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was postoperative mortality or organ system complication (stroke, prolonged ventilation, reintubation, cardiac arrest, acute kidney injury, new-onset atrial fibrillation). After adjustment, SMII

Failure to rescue (FTR), defined as death after a complication, is recognized as a principal driver of variation in mortality among hospitals. We evaluated FTR as a quality metric in patients who received durable left ventricular assist devices (LVADs) using the Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support.Data on 13,617 patients who received primary durable LVADs from April 2012 to October 2017 at 131 hospitals that performed at least 20 implants were analyzed from the Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support. Rates of major complications and FTR were compared across risk-adjusted in-hospital mortality terciles (low, medium, high) and hospital volume. Logistic regression was used to estimate expected FTR rates on the basis of patient factors for each major complication.The overall unadjusted in-hospital mortality rate was 6.96%. Risk-adjusted in-hospital mortality rates varied 3.1-fold across terciles (low, 3.3%; high, 10.3%; P trend.001). Rates of major complications varied 1.1-fold (low, 34.0%; high, 38.8%; P .0001). Among patients with a major complication, 854 died in-hospital for an FTR rate of 17.7%, with 2.8-fold variation across mortality terciles (low, 8.5%; high, 23.9%; P .0001). FTR rates were highest for renal dysfunction requiring dialysis (45.3%) and stroke (36.5%). Higher average annual LVAD volume was associated with higher rates of major complications (10 per year, 26.7%; 10-20 per year, 34.0%; 20-30 per year, 34.0%;30 per year, 40.1%; P trend.0001) whereas hospitals implanting10 per year had the highest FTR rate (10 per year, 23.5%; 10-20 per year, 16.5%; 20-30 per year, 17.0%;30 per year, 17.9%; P = .03).FTR might serve as an important quality metric for durable LVAD implant procedures, and identifying strategies for successful rescue after complications might reduce hospital variations in mortality.

Background Heart failure with reduced ejection fraction (HFrEF) is a condition imposing significant health care burden. Given its syndromic nature and often insidious onset, the diagnosis may not be made until clinical manifestations prompt further evaluation. Detecting HFrEF in precursor stages could allow for early initiation of treatments to modify disease progression. Granular data collected during the perioperative period may represent an underutilized method for improving the diagnosis of HFrEF. We hypothesized that patients ultimately diagnosed with HFrEF following surgery can be identified via machine-learning approaches using pre- and intraoperative data. Methods Perioperative data were reviewed from adult patients undergoing general anesthesia for major surgical procedures at an academic quaternary care center between 2010 and 2016. Patients with known HFrEF, heart failure with preserved ejection fraction, preoperative critical illness, or undergoing cardiac, cardiology, or electrophysiologic procedures were excluded. Patients were classified as healthy controls or undiagnosed HFrEF. Undiagnosed HFrEF was defined as lacking a HFrEF diagnosis preoperatively but establishing a diagnosis within 730 days postoperatively. Undiagnosed HFrEF patients were adjudicated by expert clinician review, excluding cases for which HFrEF was secondary to a perioperative triggering event, or any event not associated with HFrEF natural disease progression. Machine-learning models, including L1 regularized logistic regression, random forest, and extreme gradient boosting were developed to detect undiagnosed HFrEF, using perioperative data including 628 preoperative and 1195 intraoperative features. Training/validation and test datasets were used with parameter tuning. Test set model performance was evaluated using area under the receiver operating characteristic curve (AUROC), positive predictive value, and other standard metrics. Results Among 67,697 cases analyzed, 279 (0.41%) patients had undiagnosed HFrEF. The AUROC for the logistic regression model was 0.869 (95% confidence interval, 0.829-0.911), 0.872 (0.836-0.909) for the random forest model, and 0.873 (0.833-0.913) for the extreme gradient boosting model. The corresponding positive predictive values were 1.69% (1.06%-2.32%), 1.42% (0.85%-1.98%), and 1.78% (1.15%-2.40%), respectively. Conclusions Machine-learning models leveraging perioperative data can detect undiagnosed HFrEF with good performance. However, the low prevalence of the disease results in a low positive predictive value, and for clinically meaningful sensitivity thresholds to be actionable, confirmatory testing with high specificity (eg, echocardiography or cardiac biomarkers) would be required following model detection. Future studies are necessary to externally validate algorithm performance at additional centers and explore the feasibility of embedding algorithms into the perioperative electronic health record for clinician use in real time.

BackgroundDespite the significant healthcare impact of acute kidney injury, little is known regarding prevention. Single-center data have implicated hypotension in developing postoperative acute kidney injury. The generalizability of this finding and the interaction between hypotension and baseline patient disease burden remain unknown. The authors sought to determine whether the association between intraoperative hypotension and acute kidney injury varies by preoperative risk.MethodsMajor noncardiac surgical procedures performed on adult patients across eight hospitals between 2008 and 2015 were reviewed. Derivation and validation cohorts were used, and cases were stratified into preoperative risk quartiles based upon comorbidities and surgical procedure. After preoperative risk stratification, associations between intraoperative hypotension and acute kidney injury were analyzed. Hypotension was defined as the lowest mean arterial pressure range achieved for more than 10 min; ranges were defined as absolute (mmHg) or relative (percentage of decrease from baseline).ResultsAmong 138,021 cases reviewed, 12,431 (9.0%) developed postoperative acute kidney injury. Major risk factors included anemia, estimated glomerular filtration rate, surgery type, American Society of Anesthesiologists Physical Status, and expected anesthesia duration. Using such factors and others for risk stratification, patients with low baseline risk demonstrated no associations between intraoperative hypotension and acute kidney injury. Patients with medium risk demonstrated associations between severe-range intraoperative hypotension (mean arterial pressure less than 50 mmHg) and acute kidney injury (adjusted odds ratio, 2.62; 95% CI, 1.65 to 4.16 in validation cohort). In patients with the highest risk, mild hypotension ranges (mean arterial pressure 55 to 59 mmHg) were associated with acute kidney injury (adjusted odds ratio, 1.34; 95% CI, 1.16 to 1.56). Compared with absolute hypotension, relative hypotension demonstrated weak associations with acute kidney injury not replicable in the validation cohort.ConclusionsAdult patients undergoing noncardiac surgery demonstrate varying associations with distinct levels of hypotension when stratified by preoperative risk factors. Specific levels of absolute hypotension, but not relative hypotension, are an important independent risk factor for acute kidney injury.Editor’s PerspectiveWhat We Already Know about This TopicWhat This Article Tells Us That Is New

Objectives We examined for differences in pre–left ventricular assist device (LVAD) implantation myocardial transcriptome signatures among patients with different degrees of mitral regurgitation (MR). Methods Between January 2018 and October 2019, we collected left ventricular (LV) cores during durable LVAD implantation (n = 72). A retrospective chart review was performed. Total RNA was isolated from LV cores and used to construct cDNA sequence libraries. The libraries were sequenced with the NovaSeq system, and data were quantified using Kallisto. Gene Set Enrichment Analysis (GSEA) and Gene Ontology analyses were performed, with a false discovery rate Results Comparing patients with preoperative mild or less MR (n = 30) and those with moderate-severe MR (n = 42), the moderate-severe MR group weighted less (P = .004) and had more tricuspid valve repairs (P = .043), without differences in demographics or comorbidities. We then compared both groups with a group of human donor hearts without heart failure (n = 8). Compared with the donor hearts, there were 3985 differentially expressed genes (DEGs) for mild or less MR and 4587 DEGs for moderate-severe MR. Specifically altered genes included 448 DEGs for specific for mild or less MR and 1050 DEGs for moderate-severe MR. On GSEA, common regulated genes showed increased immune gene expression and reduced expression of contraction and energetic genes. Of the 1050 genes specific for moderate-severe MR, there were additional up-regulated genes related to inflammation and reduced expression of genes related to cellular proliferation. Conclusions Patients undergoing durable LVAD implantation with moderate-severe MR had increased activation of genes related to inflammation and reduction of cellular proliferation genes. This may have important implications for myocardial recovery.

BackgroundOf the 150,000 patients annually undergoing coronary artery bypass grafting, 35% develop complications that increase mortality 5 fold and expenditure by 50%. Differences in patient risk and operative approach explain only 2% of hospital variations in some complications. The intraoperative phase remains understudied as a source of variation, despite its complexity and amenability to improvement.ObjectiveThe objectives of this study are to (1) investigate the relationship between peer assessments of intraoperative technical skills and nontechnical practices with risk-adjusted complication rates and (2) evaluate the feasibility of using computer-based metrics to automate the assessment of important intraoperative technical skills and nontechnical practices.MethodsThis multicenter study will use video recording, established peer assessment tools, electronic health record data, registry data, and a high-dimensional computer vision approach to (1) investigate the relationship between peer assessments of surgeon technical skills and variability in risk-adjusted patient adverse events; (2) investigate the relationship between peer assessments of intraoperative team-based nontechnical practices and variability in risk-adjusted patient adverse events; and (3) use quantitative and qualitative methods to explore the feasibility of using objective, data-driven, computer-based assessments to automate the measurement of important intraoperative determinants of risk-adjusted patient adverse events.ResultsThe project has been funded by the National Heart, Lung and Blood Institute in 2019 (R01HL146619). Preliminary Institutional Review Board review has been completed at the University of Michigan by the Institutional Review Boards of the University of Michigan Medical School.ConclusionsWe anticipate that this project will substantially increase our ability to assess determinants of variation in complication rates by specifically studying a surgeon’s technical skills and operating room team member nontechnical practices. These findings may provide effective targets for future trials or quality improvement initiatives to enhance the quality and safety of cardiac surgical patient care.International Registered Report Identifier (IRRID)PRR1-10.2196/22536

Objectives: To determine the association between access to health care among pregnant women in Malawi and occurrence of obstetric vesicovaginal fistula (VVF). Methods: This was a case-control study using data obtained from patients’ records documented by the ‘Fistula Care Center-Bwaila Hospital’ in Malawi. Socio-demo graph ic characteristics of women with VVF (study arm, n=1046) and perineal tear (control arm, n=37) were examined. A composite variable called “Malawi Healthcare Access Index” (MHAI) was created through summation of scores related to three factors of access to care: (1) walking distance to closest health center; (2) presence of trained provider at delivery; and (3) receipt of antenatal care. Binomial logistic regression models were built to determine the association between the MHAI and presence of VVF. Results: Obstetric VVF was more common in women from rural areas, mothers delivering at extremes of age, those with less education, and patients with long labor (>12 hours). In adjusted models, women with “insufficient” health access based on the MHAI were at greater risk (OR = 2.64, 95%CI = 1.07 – 6.03) of obstetric VVF than women with “sufficient” score on the MHAI. Conclusion and Global Health Implications: Inadequate access to essential obstetric care increases the risk of VVF. Key words: • Health care index • Obstetric complications • Vesicovaginal fistula • Poverty • Malawi • Malawi Healthcare Access Index Copyright © 2020 Rupley et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Compared with historic ventilation strategies, modern lung-protective ventilation includes lower tidal volumes (VT), lower driving pressures, and application of positive end-expiratory pressure (PEEP). The contributions of each component to an overall intraoperative protective ventilation strategy aimed at reducing postoperative pulmonary complications have neither been adequately resolved, nor comprehensively evaluated within an adult cardiac surgical population. The authors hypothesized that a bundled intraoperative protective ventilation strategy was independently associated with decreased odds of pulmonary complications after cardiac surgery. Methods In this observational cohort study, the authors reviewed nonemergent cardiac surgical procedures using cardiopulmonary bypass at a tertiary care academic medical center from 2006 to 2017. The authors tested associations between bundled or component intraoperative protective ventilation strategies (VT below 8 ml/kg ideal body weight, modified driving pressure [peak inspiratory pressure − PEEP] below 16 cm H2O, and PEEP greater than or equal to 5 cm H2O) and postoperative outcomes, adjusting for previously identified risk factors. The primary outcome was a composite pulmonary complication; secondary outcomes included individual pulmonary complications, postoperative mortality, as well as durations of mechanical ventilation, intensive care unit stay, and hospital stay. Results Among 4,694 cases reviewed, 513 (10.9%) experienced pulmonary complications. After adjustment, an intraoperative lung-protective ventilation bundle was associated with decreased pulmonary complications (adjusted odds ratio, 0.56; 95% CI, 0.42–0.75). Via a sensitivity analysis, modified driving pressure below 16 cm H2O was independently associated with decreased pulmonary complications (adjusted odds ratio, 0.51; 95% CI, 0.39–0.66), but VT below 8 ml/kg and PEEP greater than or equal to 5 cm H2O were not. Conclusions The authors identified an intraoperative lung-protective ventilation bundle as independently associated with reduced pulmonary complications after cardiac surgery. The findings offer insight into components of protective ventilation associated with adverse outcomes and may serve as targets for future prospective interventional studies investigating the impact of specific protective ventilation strategies on postoperative outcomes after cardiac surgery.

A 53-year-old woman with migraines presented with Hunt-Hess grade 5 and Fisher grade 4 subarachnoid hemorrhage with intraventricular hemorrhage. She experienced severe vasospasm requiring intra-arterial medications. Continued vasospasm and edema resulted in Cushing's triad with profound tachypnea. Three percentage saline was administered twice without improvement. Despite the general practice to wait until complete neurologic deterioration before administering 23.4% saline, it was administered on 2 separate occasions, once after the failure of the 2 boluses of 3% saline and once on the reappearance of Cushing's triad 24 hours later, and on each occasion produced overall clinical improvement. The patient was subsequently discharged to a rehabilitation facility and then home. A paradigm shift to earlier intervention with 23.4% saline may improve overall outcomes in patients with severe intracranial hypertension refractory to 3% saline and impending herniation.

Background: The current study was designed to test the hypothesis that the fibromyalgia survey criteria would be directly associated with increased opioid consumption after hysterectomy even when accounting for other factors previously described as being predictive for acute postoperative pain. Methods: Two hundred eight adult patients undergoing hysterectomy between October 2011 and December 2013 were phenotyped preoperatively with the use of validated self-reported questionnaires including the 2011 fibromyalgia survey criteria, measures of pain severity and descriptors, psychological measures, preoperative opioid use, and health information. The primary outcome was the total postoperative opioid consumption converted to oral morphine equivalents. Results: Higher fibromyalgia survey scores were significantly associated with worse preoperative pain characteristics, including higher pain severity, more neuropathic pain, greater psychological distress, and more preoperative opioid use. In a multivariate linear regression model, the fibromyalgia survey score was independently associated with increased postoperative opioid consumption, with an increase of 7-mg oral morphine equivalents for every 1-point increase on the 31-point measure (Estimate, 7.0; Standard Error, 1.7; P < 0.0001). In addition to the fibromyalgia survey score, multivariate analysis showed that more severe medical comorbidity, catastrophizing, laparotomy surgical approach, and preoperative opioid use were also predictive of increased postoperative opioid consumption. Conclusions: As was previously demonstrated in a total knee and hip arthroplasty cohort, this study demonstrated that increased fibromyalgia survey scores were predictive of postoperative opioid consumption in the posthysterectomy surgical population during their hospital stay. By demonstrating the generalizability in a second surgical cohort, these data suggest that patients with fibromyalgia-like characteristics may require a tailored perioperative analgesic regimen.

Background: Variance in pain after total knee and hip arthroplasty may be due to a number of procedural and peripheral factors but also, in some individuals, to aberrant central pain processing as is described in conditions like fibromyalgia. To test this hypothesis, the authors conducted a prospective, observational cohort study of patients undergoing lower-extremity joint arthroplasty. Methods: Five hundred nineteen patients were preoperatively phenotyped using validated self-reported pain questionnaires, psychological measures, and health information. In addition to being assessed for factors previously found to be associated with poor outcomes in arthroplasty, participants also completed the American College of Rheumatology survey criteria for fibromyalgia. Previous studies have suggested that rather than being “present” or “absent,” features of fibromyalgia as measured by this instrument, occur over a wide continuum. Postoperative pain control was assessed by total postoperative opioid consumption. Results: Preoperatively, patients with higher fibromyalgia survey scores were younger, more likely to be female, taking more opioids, reported higher pain severity, and had a more negative psychological profile. In the multivariate analysis, the fibromyalgia survey score, younger age, preoperative opioid use, knee (vs. hip), pain severity at baseline, and the anesthetic technique were all predictive of increased postoperative opioid consumption. Conclusions: The use of the survey criteria for fibromyalgia led to the finding of distinct phenotypic differences, and the measure was independently predictive of opioid consumption. This self-report measure may provide an additional simple means of predicting postoperative pain outcomes and analgesic requirements. Future studies are needed to determine whether tailored therapies can improve postoperative pain control in this population.

Background Pregnancy after solid organ transplant is a significant priority for transplant recipients but how patients report being counseled is unknown. Methods We performed a single-center retrospective cohort study and telephone survey of female patients ages 18–49 at the time of kidney, pancreas, or liver transplant from 2000 to 2012 (n = 532). Data on pregnancy counseling, fertility, and maternal, fetal- and transplant-specific outcomes were collected. Multivariate Cox models assessed the impact of pregnancy on graft-specific outcomes. Results The survey response rate was 29% (n = 152). One-third (n = 51) of women were actively counseled against pregnancy by one or more providers. A total of 17 pregnancies occurred among nine patients (5.9%), with 47% live births, 47% early embryonic demises, 5.9% stillbirths. Of live births, 50% were premature. Gestational complications, including diabetes, hypertension, and preeclampsia were present in 88% of mothers. Pregnancy after transplant was associated with higher rates of acute rejection than nulliparous transplant recipients (33% vs. 5.6%, p = 0.07) but did not significantly affect graft survival (HR = 1.00, 95% CI 0.99–1.01), after stratifying by organ and adjusting for clinical factors. Conclusion This study suggests that transplant patients are being counseled against pregnancy despite acceptable risks of complications and no specific effects on long-term graft function.

Ropivacaine has been associated with transient heat hyperalgesia in sciatic nerve blocks in rat. The goal of the present study was to evaluate the hypothesized presence of transient heat hyperalgesia after perineural injection of ropivacaine with a secondary subanalysis of 2 published studies. Paw withdrawal latency was used to assess the duration of sensory blockade and presence of heat hyperalgesia at 210, 240, 270, and 300 minutes and 24 hours after injection. The analysis revealed hyperalgesia at a single time point (240 minutes after injection; mean difference, −0.60 seconds; P = 0.012) that resolved within 30 minutes, and there was no other significant hyperalgesia at other time points. Although statistically significant, the single time point measurement represented only an 11% change from baseline and was no longer present 30 minutes later. These data support the need for a reevaluation of the interpretation that pain can be worsened by perineural ropivacaine injection.

Background The current study was designed to test the hypothesis that the increased duration of analgesia caused by adding dexmedetomidine to local anesthetic results from blockade of the hyperpolarization-activated cation (I(h)) current. Methods In this randomized, blinded, controlled study, the analgesic effects of peripheral nerve blocks using 0.5% ropivacaine alone or 0.5% ropivacaine plus dexmedetomidine (34 μM or 6 μg/kg) were assessed with or without the pretreatment of α(1)- and α(2)-adrenoceptor antagonists (prazosin and idazoxan, respectively) and antagonists and agonists of the I(h) current (ZD 7288 and forskolin, respectively). Sciatic nerve blocks were performed, and analgesia was measured by paw withdrawal latency to a thermal stimulus every 30 min for 300 min postblock. Results The analgesic effect of dexmedetomidine added to ropivacaine was not reversed by either prazosin or idazoxan. There were no additive or attenuated effects from the pretreatment with ZD 7288 (I(h) current blocker) compared with dexmedetomidine added to ropivacaine. When forskolin was administered as a pretreatment to ropivacaine plus dexmedetomidine, there were statistically significant reductions in duration of analgesia at time points 90-180 min (P < 0.0001 for each individual comparison). The duration of blockade for the forskolin (768 μM) followed by ropivacaine plus dexmedetomidine group mirrored the pattern of the ropivacaine alone group, thereby implying a reversal effect. Conclusion Dexmedetomidine added to ropivacaine caused approximately a 75% increase in the duration of analgesia, which was reversed by pretreatment with an I(h) current enhancer. The analgesic effect of dexmedetomidine was not reversed by an α(2)-adrenoceptor antagonist.

The present study was designed to test the hypothesis that perineural dexmedetomidine provides a longer duration of analgesia than the same dose given subcutaneously in a peripheral nerve block in rats.Fifty-four rats received unilateral sciatic nerve blocks along with a subcutaneous injection at the base of the neck by a blinded investigator assigned at random. Combinations were as follows: perineural ropivacaine alone and subcutaneous (SQ) saline, perineural ropivacaine plus dexmedetomidine and SQ saline, perineural ropivacaine and SQ dexmedetomidine, perineural dexmedetomidine alone and SQ saline, and perineural saline and SQ dexmedetomidine. The ropivacaine concentration was fixed at 0.5%, and the dose of dexmedetomidine was 20.0 microg/kg (119.3 micromol/L). Sensory analgesia was assessed by paw withdrawal latency (PWL) to a thermal stimulus every 30 mins after the block for a minimum of 240 mins or until the return of normal sensory function. The unblocked paw served as the control for assessment of systemic, centrally mediated analgesia. Between-group and within-group comparisons of PWL were obtained for measures from operative and control paws.The analgesic effect of perineural dexmedetomidine was superior to that of subcutaneous dexmedetomidine in ropivacaine sciatic nerve blocks from time points 120 to 210 mins (P0.017). Perineural dexmedetomidine also showed less systemic effect as measured by the unblocked control paw at multiple time points (P0.05). Perineural dexmedetomidine alone provided a brief, partial sensory block.Sensory analgesia provided by dexmedetomidine added to ropivacaine for peripheral nerve blocks in rat is a peripherally mediated effect.