Candidate Kidney Protective Strategies for Patients Undergoing Major Abdominal Surgery: A Secondary Analysis of the RELIEF Trial Cohort.

BACKGROUND: Acute kidney injury (AKI) is common after major abdominal surgery. Selection of candidate kidney protective strategies for testing in large trials should be based on robust preliminary evidence. METHODS: A secondary analysis of the Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery (RELIEF) trial was conducted in adult patients undergoing major abdominal surgery and randomly assigned to a restrictive or liberal perioperative fluid regimen. The primary outcome was maximum AKI stage before hospital discharge. Two multivariable ordinal regression models were developed to test the primary hypothesis that modifiable risk factors associated with increased maximum stage of postoperative AKI could be identified. Each model used a separate approach to variable selection to assess the sensitivity of the findings to modeling approach. For model 1, variable selection was informed by investigator opinion; for model 2, the Least Absolute Shrinkage and Selection Operator (LASSO) technique was used to develop a data-driven model from available variables. RESULTS: Of 2,444 patients analyzed, stage 1, 2, and 3 AKI occurred in 223 (9.1%), 59 (2.4%), and 36 (1.5%) patients, respectively. In multivariable modeling by model 1, administration of a nonsteroidal anti-inflammatory drug or cyclooxygenase-2 inhibitor, intraoperatively only (odds ratio, 1.77 [99% CI, 1.11 to 2.82]), and preoperative day-of-surgery administration of an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker compared to no regular use (odds ratio, 1.84 [99% CI, 1.15 to 2.94]) were associated with increased odds for greater maximum stage AKI. These results were unchanged in model 2, with the additional finding of an inverse association between nadir hemoglobin concentration on postoperative day 1 and greater maximum stage AKI. CONCLUSIONS: Avoiding intraoperative nonsteroidal anti-inflammatory drugs or cyclooxygenase-2 inhibitors is a potential strategy to mitigate the risk for postoperative AKI. The findings strengthen the rationale for a clinical trial comprehensively testing the risk-benefit ratio of these drugs in the perioperative period.

Determinants and practice variability of oxygen administration during surgery in the U.S., a retrospective cohort study.

BACKGROUND: The best approaches to supplemental oxygen administration during surgery remain unclear, which may contribute to variation in practice. We aimed to assess determinants of oxygen administration and its variability during surgery. METHODS: Using multivariable linear mixed-effects regression, we measured the associations between intraoperative fraction of inspired oxygen and patient, procedure, medical center, anesthesiologist, and in-room anesthesia provider factors in surgical cases of 120 minutes or longer in adult patients who received general anesthesia with tracheal intubation and were admitted to the hospital after surgery between January 2016 and January 2019 at 42 medical centers across the U.S. participating in the Multicenter Perioperative Outcomes Group data registry. RESULTS: The sample included 367,841 cases (median [25 th, 75 th] age, 59 [47, 69] years; 51.1% women; 26.1% treated with nitrous oxide) managed by 3,836 anesthesiologists and 15,381 in-room anesthesia providers. Median (25 th, 75 th) fraction of inspired oxygen was 0.55 (0.48, 0.61), with 6.9% of cases <0.40 and 8.7% >0.90. Numerous patient and procedure factors were statistically associated with increased inspired oxygen, notably advanced ASA classification, heart disease, emergency surgery, and cardiac surgery, but most factors had little clinical significance (<1% inspired oxygen change). Overall, patient factors only explained 3.5% (95% CI, 3.5 to 3.5) of the variability in oxygen administration and procedure factors 4.4% (4.2 to 4.6). Anesthesiologist explained 7.7% (7.2 to 8.2) of the variability in oxygen administration, in-room anesthesia provider 8.1% (7.8 to 8.4), medical center 23.3% (22.4 to 24.2), and 53.0% (95% CI, 52.4 to 53.6) was unexplained. CONCLUSIONS: Among adults undergoing surgery with anesthesia and tracheal intubation, supplemental oxygen administration was variable and appeared arbitrary. Most patient and procedure factors had statistical but minor clinical associations with oxygen administration. Medical center and anesthesia provider explained significantly more variability in oxygen administration than patient or procedure factors.

Predictive modelling for postoperative acute kidney injury: big data enhancing quality or the Emperor's new clothes?

The increased availability of large clinical datasets together with increasingly sophisticated computing power has facilitated development of numerous risk prediction models for various adverse perioperative outcomes, including acute kidney injury (AKI). The rationale for developing such models is straightforward. However, despite numerous purported benefits, the uptake of preoperative prediction models into clinical practice has been limited. Barriers to implementation of predictive models, including limitations in their discrimination and accuracy, as well as their ability to meaningfully impact clinical practice and patient outcomes, are increasingly recognised. Some of the purported benefits of predictive modelling, particularly when applied to postoperative AKI, might not fare well under detailed scrutiny. Future research should address existing limitations and seek to demonstrate both benefit to patients and value to healthcare systems from implementation of these models in clinical practice.

Poor Agreement Between Preoperative Transthoracic Echocardiography and Intraoperative Transesophageal Echocardiography for Grading Diastolic Dysfunction.

BACKGROUND: Guidelines for the evaluation and grading of diastolic dysfunction are available for transthoracic echocardiography (TTE). Transesophageal echocardiography (TEE) is used for this purpose intraoperatively but the level of agreement between these 2 imaging modalities for grading diastolic dysfunction is unknown. We assessed agreement between awake preoperative TTE and intraoperative TEE for grading diastolic dysfunction. METHODS: In 98 patients undergoing cardiac surgery, key Doppler measurements were obtained using TTE and TEE at the following time points: TTE before anesthesia induction (TTEawake), TTE following anesthesia induction (TTEanesth), and TEE following anesthesia induction (TEEanesth). The primary endpoint was grade of diastolic dysfunction categorized by a simplified algorithm, and measured by TTEawake and TEEanesth, for which the weighted κ statistic assessed observed agreement beyond chance. Secondary endpoints were peak early diastolic lateral mitral annular tissue velocity (e'lat) and the ratio of peak early diastolic mitral inflow velocity (E) to e'lat (E/e'lat), measured by TTEawake and TEEanesth, were compared using Bland-Altman limits of agreement. RESULTS: Disagreement in grading diastolic dysfunction by ≥1 grade occurred in 43 (54%) of 79 patients and by ≥2 grades in 8 (10%) patients with paired measurements for analysis, yielding a weighted κ of 0.35 (95% confidence interval [CI], 0.19-0.51) for the observed level of agreement beyond chance. Bland-Altman analysis of paired data for e'lat and E/e'lat demonstrated a mean difference (95% CI) of 0.51 (-0.06 to 1.09) and 0.70 (0.07-1.34), respectively, for measurements made by TTEawake compared to TEEanesth. The percentage (95% CI) of paired measurements for e'lat and E/e'lat that lay outside the [-2, +2] study-specified boundary of acceptable agreement was 36% (27%-48%) and 39% (29%-51%), respectively. Results were generally robust to sensitivity analyses, including comparing measurements between TTEawake and TTEanesth, between TTEanesth and TEEanesth, and after regrading diastolic dysfunction by the American Society of Echocardiography (ASE)/European Association of CardioVascular Imaging (EACVI) algorithm. CONCLUSIONS: There was poor agreement between TTEawake and TEEanesth for grading diastolic dysfunction by a simplified algorithm, with disagreement by ≥1 grade in 54% and by ≥2 grades in 10% of the evaluable cohort. Future studies, including comparing the prognostic utility of TTEawake and TEEanesth for clinically important adverse outcomes that may be a consequence of diastolic dysfunction, are needed to understand whether this disagreement reflects random variability in Doppler variables, misclassification by the changed technique and physiological conditions of intraoperative TEE, or the accurate detection of a clinically relevant change in diastolic dysfunction.

Correction: Voltammetric pH sensor based on electrochemically modified pseudo-graphite.

Correction for 'Voltammetric pH sensor based on electrochemically modified pseudo-graphite' by Haoyu Zhu et al., Analyst, 2020, 145, 7252-7259, https://doi.org/10.1039/D0AN01405B.

Evaluating the role and effectiveness of co-produced community-based mental health interventions that aim to reduce suicide among adults: A systematic review.

BACKGROUND: Suicide is a major public health risk requiring targeted suicide prevention interventions. The principles of co-production are compatible with tailoring suicide prevention interventions to meet an individual's needs. AIMS: This review aimed to evaluate the role and effectiveness of co-produced community-based suicide prevention interventions among adults. METHODS: Four electronic databases (PsycInfo, CINAHL, MEDLINE and web of science) were systematically searched. A narrative synthesis was conducted. RESULTS: From 590 papers identified through searches, 14 fulfilled the inclusion criteria. Most included studies elicited the views and perspectives of stakeholders in a process of co-design/co-creation of community-based suicide prevention interventions. CONCLUSION: Stakeholder involvement in the creation of community-based suicide prevention interventions may improve engagement and give voice to those experiencing suicidal crisis. However, there is limited evaluation extending beyond the design of these interventions. Further research is needed to evaluate the long-term outcomes of co-produced community-based suicide prevention interventions. PATIENT AND PUBLIC INVOLVEMENT: This paper is a systematic review and did not directly involve patients and/or the public. However, the findings incorporate the views and perspectives of stakeholders as reported within the studies included in this review, and the findings may inform the future involvement of stakeholders in the design, development and delivery of community-based suicide prevention interventions for adults.

Effects of Postoperative Blood Pressure Management on Delirium Among Patients in the Intensive Care Unit After Cardiac Surgery: An Observational Cohort Study.

OBJECTIVES: This study aimed to determine whether blood pressure control in the early postoperative period was associated with postoperative delirium in the cardiovascular intensive care unit (ICU). DESIGN: Observational cohort study. SETTING: Single large academic institution with a high volume of cardiac surgery. PARTICIPANTS: Cardiac surgery patients admitted to the cardiovascular ICU after surgery. INTERVENTIONS: Observational study. MEASUREMENTS AND MAIN RESULTS: A total of 517 cardiac surgery patients had mean arterial pressure (MAP) data recorded minute-by-minute for 12 postoperative hours. The time spent in each of the 7 prespecified blood pressure bands was calculated, and the development of delirium was recorded in the ICU. A multivariate Cox regression model was developed using the least absolute shrinkage and selection operator approach to identify associations between time spent in each MAP range band and delirium. Compared with the reference band of 60-to-69 mmHg, longer durations spent in 3 bands were independently associated with a lower risk of delirium: 50-to-59 mmHg band (adjusted hazard ratio [HR] 0.907 [per 10 minutes]; 95% CI 0.861-0.955); 70-to-79 mmHg band (adjusted HR 0.923 [per 10 minutes]; 95% CI 0.902-0.944); 90-to-99 mmHg band (adjusted HR 0.898 [per 10 minutes]; 95% CI 0.853-0.945). CONCLUSIONS: The MAP range bands above and below the authors' reference band of 60-to- 69 mmHg were associated with decreased risk of ICU delirium development; however, this was difficult to reconcile with a plausible biologic mechanism. Therefore, the authors did not find a correlation between early postoperative MAP control and increased risk of the development of ICU delirium after cardiac surgery.

Translating evidence into practice: still a way to go.

Chiu and colleagues report a retrospective analysis describing the 5-yr trend in both intraoperative fluid and vasopressor administration in 32 250 patients undergoing elective abdominal surgery within the Multicenter Perioperative Outcomes Group (MPOG) database from 2015 to 2019, and exploring the association between these two factors and acute kidney injury. Modelling predicted the lowest risk for acute kidney injury when the administered crystalloid volume was 15-20 ml kg-1 h-1, and an 80% increase in risk for acute kidney injury as intraoperative vasopressor use increased from 0 to 0.04 µg kg-1 min-1 of norepinephrine equivalents. Although these results are consistent with those of a large, randomised trial (REstrictive Versus LIbEral Fluid Therapy in Major Abdominal Surgery [RELIEF]) published in 2018, the mean intraoperative volume of crystalloid administered in the current study declined monotonically through every year included, from 6.4 ml kg-1 h-1 in 2015 to 5.5 ml kg-1 h-1 in 2019. These new findings support the broad generalisability of the RELIEF trial; highlight the complexity of the relationship between intravenous crystalloid volume infused, arterial pressure, and acute kidney injury; and demonstrate the ongoing challenge of translating high-quality evidence into clinical practice.

Society of Cardiovascular Anesthesiologists Clinical Practice Update for Management of Acute Kidney Injury Associated With Cardiac Surgery.

Cardiac surgery-associated acute kidney injury (CS-AKI) is common and is associated with increased risk for postoperative morbidity and mortality. Our recent survey of the Society of Cardiovascular Anesthesiologists (SCA) membership showed 6 potentially renoprotective strategies for which clinicians would most value an evidence-based review (ie, intraoperative target blood pressure, choice of specific vasopressor agent, erythrocyte transfusion threshold, use of alpha-2 agonists, goal-directed oxygen delivery on cardiopulmonary bypass [CPB], and the "Kidney Disease Improving Global Outcomes [KDIGO] bundle of care"). Thus, the SCA's Continuing Practice Improvement Acute Kidney Injury Working Group aimed to provide a practice update for each of these strategies in cardiac surgical patients based on the evidence from randomized controlled trials (RCTs). PubMed, EMBASE, and Cochrane library databases were comprehensively searched for eligible studies from inception through February 2021, with search results updated in August 2021. A total of 15 RCTs investigating the effects of the above-mentioned strategies on CS-AKI were included for meta-analysis. For each strategy, the level of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology. Across the 6 potentially renoprotective strategies evaluated, current evidence for their use was rated as "moderate," "low," or "very low." Based on eligible RCTs, our analysis suggested using goal-directed oxygen delivery on CPB and the "KDIGO bundle of care" in high-risk patients to prevent CS-AKI (moderate level of GRADE evidence). Our results suggested considering the use of vasopressin in vasoplegic shock patients to reduce CS-AKI (low level of GRADE evidence). The decision to use a restrictive versus liberal strategy for perioperative red cell transfusion should not be based on concerns for renal protection (a moderate level of GRADE evidence). In addition, targeting a higher mean arterial pressure during CPB, perioperative use of dopamine, and use of dexmedetomidine did not reduce CS-AKI (a low or very low level of GRADE evidence). This review will help clinicians provide evidence-based care, targeting improved renal outcomes in adult patients undergoing cardiac surgery.

Is an Acute Perioperative Increase in Creatinine Production Rate a Potential Mechanism for an Early Creatinine-Based Signal of Renal Injury After Cardiac Surgery?

OBJECTIVES: Previous studies report a creatinine-based signal of injury within hours after cardiac surgery, which is sooner than expected based on creatinine kinetic modelling. A plausible mechanism for such an early signal has not been established, but might be explained by an acute perioperative increase in creatinine production rate (Crprod-rate). The authors sought to test the hypothesis that perioperative Crprod-rate increases from baseline in patients undergoing cardiac surgery. DESIGN: Prospective cohort study. SETTING: Academic medical center. PARTICIPANTS: Fifty adult male patients undergoing cardiac surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Based on the principle of conservation of mass, precisely timed serial measurements of patient weight, plasma and urine creatinine concentration, and urine volume were used to calculate Crprod-rate over 3 consecutive periods: a baseline period immediately before surgery (period 0), the 24-hour period starting from induction of anesthesia (period 1), and again from 24 to 48 hours after induction of anesthesia (period 2). The primary outcome was change in Crprod-rate from period 0 to period 1 (∆Crprod-rate0-1). Median Crprod-rate0 was 5.4 (interquartile range [IQR], 4.7-5.7) µmol/kg/h at baseline and increased to 6.1 (IQR, 5.6-6.5) µmol/kg/h during period 1, a median increase of 14% (95% CI, 8%-27%; p = 0.002). ∆Crprod-rate0-1 ranged from -58% to +129%, with an increase above baseline in 25 patients (76%) and an increase by ≥30% above baseline in 10 patients (30%). CONCLUSIONS: Perioperative Crprod-rate increased from baseline in patients undergoing cardiac surgery. This may represent a mechanism for an earlier creatinine-based signal of renal injury than previously thought possible.

The associations of use of social network sites with perceived social support and loneliness.

Research shows that use of social network sites is associated with loneliness and this may be amplified in tertiary students by their transition from home life, especially if they struggle to integrate with peers. The buffering effects of social support may offer a solution and the online dimension may offer a suitable outlet for lonely and isolated students. In this study, N = 111 university students, aged 18-40, completed a frequency assessment of Instagram and WhatsApp, the Spanish version of the UCLA loneliness scale and the Multidimensional Scale of Social Support in an online survey. The statistical analysis was completed by Structural Equation Modeling using AMOS 25.0. The construct validity of social network sites was established by good factor loadings for WhatsApp and Instagram, but Facebook was excluded as it did not load adequately on to the latent measurement model, in keeping with the diminishing trend for Facebook use in young students. Loneliness emerged as pivotal in a mediation model, and online social support from friends/significant others, emerged as salient in the predictive model in contrast to family. However, these associations may not have the same advantageous weight for mature students given the observed negative associations with age. Results may have implications for policy and planning through highlighting the psychological variables that are operative in the dynamics of integration, retention, and adjustment to tertiary level experience.

The effects of sub-bandgap transitions and the defect density of states on the photocurrent response of a single ZnO-coated silica nanospring.

The electrical and optoelectronic properties of nanometer-sized ZnO structures are highly influenced by its native point defects. Understanding and controlling these defects are essential for the development of high-performance ZnO-based devices. Here, an electrical device consisting of a polycrystalline ZnO-coated silica nanospring was fabricated and used to characterize the electrical and photoconductive properties of the ZnO layer using near-UV (405 nm) and sub-bandgap (532 and 633 nm) excitation sources. We observe a photocurrent response with all three wavelengths and notably with 532 nm green illumination, which is the energy associated with deep oxygen vacancies. The polycrystalline ZnO-coated silica nanospring exhibits a high responsivity of 1740 A W-1 with the 405 nm excitation source. Physical models are presented to describe the photocurrent rise and decay behavior of each excitation source where we suggest that the rise and decay characteristics are highly dependent on the energy of the excitation source and the trapping of electrons and holes in intermediate defect levels in the bandgap. The energy levels of the trap depths were determined from the photoconductive decay data and are matched to the reported energy levels of singly and doubly ionized oxygen vacancies. A phenomenological model to describe the dependence of the saturation photocurrent on excitation intensity is presented in order to understand the characteristics of the observed breaks in the slopes of the saturation photocurrent versus excitation intensity profile.

Predicting acute kidney injury after cardiac surgery: much work still to be done.

Accurate preoperative risk prediction for perioperative complications such as acute kidney injury (AKI) may serve to better inform patients and families of risk before surgery, assist with resource requirement planning, and aid with cohort enrichment for enrolment into clinical trials. Where a specific risk factor is modifiable, it may offer a potential therapeutic target for risk reduction. The report by Wang and colleagues describes the modest incremental benefit of N-terminal pro brain natriuretic peptide levels when added to almost 20 other variables for the preoperative prediction of AKI after cardiac surgery. This is consistent with previous smaller studies, but there are important additional questions still to be answered before this biomarker might be used for this purpose in clinical practice.

Peak Serum Chloride and Hyperchloremia in Patients Undergoing Cardiac Surgery Is Not Explained by Chloride-Rich Intravenous Fluid Alone: A Post-Hoc Analysis of the LICRA Trial.

OBJECTIVES: With the exception of 0.9% saline, little is known about factors that may contribute to increased serum chloride concentration (SCl-) in patients undergoing cardiac surgery. For the present study, the authors sought to characterize the association between administered chloride load from intravenous fluid and other perioperative variables, with peak perioperative SCl-. DESIGN: Secondary analysis of data from a previously published controlled clinical trial in which patients were assigned to a chloride-rich or chloride-limited perioperative fluid strategy (NCT02020538). SETTING: Academic medical center. PARTICIPANTS: The study comprised 1,056 adult patients with normal preoperative SCl- undergoing cardiac surgery. INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Peak perioperative SCl- and hyperchloremia, defined as peak SCl- >110 mmol/L, were selected as co-primary endpoints. Regression modeling identified factors independently associated with these endpoints. Mean (standard deviation) peak perioperative SCl- was 114 (5) mmol/L, and hyperchloremia occurred in 824 (78.0%) of the cohort. In addition to administered volume of 0.9% saline, multivariate linear and logistic regression modeling consistently associated preoperative SCl- (regression coefficient 0.5; 95% confidence interval [CI] 0.4-0.6 mmol/L; odds ratio 1.60; 95% CI 1.41-1.82 per 1 mmol/L increase) and cardiopulmonary bypass duration (regression coefficient 0.1; 95% CI 0.1-0.2 mmol/L; odds ratio 1.12; 95% CI 1.06-1.19 per 10 minutes) with both co-primary outcomes. Multivariate modeling only explained approximately 50% of variability in peak SCl-. CONCLUSIONS: The present study's data identified an association for both 0.9% saline administration and other nonfluid variables with peak perioperative SCl- and hyperchloremia. Stand-alone strategies to limit administration of chloride-rich intravenous fluid may have limited ability to prevent hyperchloremia in this setting.

Potential Renoprotective Strategies in Adult Cardiac Surgery: A Survey of Society of Cardiovascular Anesthesiologists Members to Explore the Rationale and Beliefs Driving Current Clinical Decision-Making.

OBJECTIVES: The authors sought to (1) characterize the rationale underpinning anesthesiologists' use of various perioperative strategies hypothesized to affect renal function in adult patients undergoing cardiac surgery, (2) characterize existing belief about the quality of evidence addressing the renal impact of these strategies, and (3) identify potentially renoprotective strategies for which anesthesiologists would most value a detailed, evidence-based review. DESIGN: Survey of perioperative practice in adult patients undergoing cardiac surgery. SETTING: Online survey. PARTICIPANTS: Members of the Society of Cardiovascular Anesthesiologists (SCA). INTERVENTIONS: None. MEASUREMENTS & MAIN RESULTS: The survey was distributed to more than 2,000 SCA members and completed in whole or in part by 202 respondents. Selection of target intraoperative blood pressure (and relative hypotension avoidance) was the strategy most frequently reported to reflect belief about its potential renal effect (79%; 95% CI: 72-85). Most respondents believed the evidence supporting an effect on renal injury of intraoperative target blood pressure during cardiac surgery was of high or moderate quality. Other factors, including a specific nonrenal rationale, surgeon preference, department- or institution-level decisions, tradition, or habit, also frequently were reported to affect decision making across queried strategies. Potential renoprotective strategies most frequently requested for inclusion in a subsequent detailed, evidence-based review were intraoperative target blood pressure and choice of vasopressor agent to achieve target pressure. CONCLUSIONS: A large number of perioperative strategies are believed to variably affect renal injury in adult patients undergoing cardiac surgery, with wide variation in perceived quality of evidence for a renal effect of these strategies.

Voltammetric pH sensor based on electrochemically modified pseudo-graphite.

A nanocrystalline graphite-like amorphous carbon (graphite from the University of Idaho thermolyzed asphalt reaction, GUITAR) shares morphological features with classical graphites, including basal and edge planes (BP, EP). However, unlike graphites and other sp2-hybridized carbons, GUITAR has fast heterogenous electron transfer (HET) across its basal planes, and resistance to corrosion similar to sp3-C and boron-doped diamond electrodes. In this contribution, quinoid modified BP-GUITAR (q-GUITAR) is examined as a sensor for pH determination. This modification is performed by applying 2.0 V (vs. Ag/AgCl) for 150 seconds followed by 15 cyclic voltammetric scans from -0.7 to 1.0 V at 50 mV s-1 in 1.0 M H2SO4. The quinoid surface coverage of q-GUITAR is 1.35 × 10-9 mol cm-2, as measured by cyclic voltammetry. X-ray photoelectron spectroscopy analysis also confirms the high surface coverage. The quinoid surface concentration ranks highest in literature when compared with other basal plane graphitic materials. This yields a sensor that responds through a square wave voltammetric reduction peak shift of 63.3 mV per pH over a pH range from 0 to 11. The response on q-GUITAR is stable for >20 measurements and no surface re-activation is required between the measurements. The common interferents, Na+, K+ and dissolved oxygen, have no effect on the response of the q-GUITAR-based pH sensor.

Low-Dose Versus Therapeutic Anticoagulation in Patients on Extracorporeal Membrane Oxygenation: A Pilot Randomized Trial.

OBJECTIVES: To determine whether randomization of patients undergoing extracorporeal membrane oxygenation to either therapeutic or a low-dose anticoagulation protocol results in a difference in activated partial thromboplastin time and anti-Xa. DESIGN: Randomized, controlled, unblinded study. SETTING: Two ICUs of two university hospitals. PATIENTS: Patients admitted to the ICU, who required extracorporeal membrane oxygenation (venovenous or venoarterial) and who did not have a preexisting indication for therapeutic anticoagulation. INTERVENTIONS: Therapeutic anticoagulation with heparin (target activated partial thromboplastin time between 50 and 70 s) or lower dose heparin (up to 12,000 U/24 hr aiming for activated partial thromboplastin time < 45 s). MEASUREMENTS AND MAIN RESULTS: Thirty-two patients were randomized into two study groups that were not significantly different in demographics and extracorporeal membrane oxygenation characteristics. There was a significant difference in the daily geometric mean heparin dose (11,742 U [95% CI, 8,601-16,031 U] vs 20,710 U [95% CI, 15,343-27,954 U]; p = 0.004), daily geometric mean activated partial thromboplastin time (48.1 s [95% CI, 43.5-53.2 s] vs 55.5 s [95% CI, 50.4-61.2 s]; p = 0.04), and daily geometric mean anti-Xa (0.11 international units/mL [95% CI, 0.07-0.18] vs 0.27 [95% CI, 0.17-0.42]; p = 0.01). We found similar results when considering only venovenous extracorporeal membrane oxygenation episodes; however, no difference in daily geometric mean activated partial thromboplastin time between groups when considering only venoarterial extracorporeal membrane oxygenation episodes. CONCLUSIONS: Allocating patients on extracorporeal membrane oxygenation to two different anticoagulation protocols led to a significant difference in mean daily activated partial thromboplastin time and anti-Xa levels between groups. When considering subgroups analyses, these results were consistent in patients on venovenous extracorporeal membrane oxygenation. Our results support the feasibility of a larger trial in patients undergoing venovenous extracorporeal membrane oxygenation to compare different anticoagulation protocols; however, this study does not provide evidence on the optimal anticoagulation protocol for patients undergoing extracorporeal membrane oxygenation.

Electrical characterization of ZnO-coated nanospring ensemble by impedance spectroscopy: probing the effect of thermal annealing.

The effects of thermal annealing on the electrical properties of randomly oriented ZnO-coated nanospring ensembles were extensively investigated through AC impedance spectroscopy. Annealing the nanospring mats for an hour at 873 K in air showed significant change in ZnO morphology, reduced electrical conductivity due to the presence of grain boundaries, decreased apparent donor concentration, and faster decay of sub-band gap photocurrent. The role of the nanospring-nanospring junctions in the conduction of carriers in the ensemble was also examined, as well as evaluation of their responsiveness to thermal and optical stimulations. This work identifies the effects of heat treatment in the presence of air on the electrical properties of the nanospring ensembles, which are related to the mesoscopic morphology and interconnect within the ensemble and the properties of the ZnO coating.

Importance of intraoperative oliguria during major abdominal surgery: findings of the Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery trial.

BACKGROUND: The association between intraoperative oliguria during major abdominal surgery and the subsequent development of postoperative acute kidney injury (AKI) remains poorly defined. We hypothesised that, in such patients, intraoperative oliguria would be an independent predictor of subsequent AKI. METHODS: We performed a post hoc analysis of data from the Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery (RELIEF) trial of conservative vs liberal fluid therapy during and after major abdominal surgery. We used χ2, logistic regression, and fractional polynomials to study the association between intraoperative oliguria defined as a urinary output <0.5 ml kg-1 h-1 and the development of postoperative AKI defined by the Kidney Disease Improving Global Outcomes consensus criteria. RESULTS: We included 2444 of 2983 patients from the RELIEF trial in this study. A total of 889 patients (36%) met oliguric criteria intraoperatively. Oliguria occurred in 35% of those without AKI, and 44%, 48%, and 45% of those who developed postoperative AKI Stages 1-3, respectively (P<0.001 for trend). Intraoperative oliguria was associated with an increased risk of AKI, risk ratio: 1.38 (95% confidence interval: 1.14-1.44; P<0.001), but greater intensity of oliguria (urine output <0.3 ml kg-1 h-1) did not increase this risk further. Most patients with oliguria did not develop AKI; the positive predictive value of oliguria was 25.5%, and the negative predictive value was 81.6%. CONCLUSIONS: Intraoperative oliguria, defined as urine output <0.5 ml kg-1 h-1, was relatively common and was associated with postoperative AKI. However, the predictive utility of oliguria for AKI was low, whilst its absence had a good predictive value for an AKI-free postoperative course. CLINICAL TRIAL REGISTRATION: NCT01424150.

Pyrenyl-carbon nanostructures for scalable enzyme electrocatalysis and biological fuel cells.

The objective of this article is to demonstrate the electrode geometric area-based scalability of pyrenyl-carbon nanostructure modification for enzyme electrocatalysis and fuel cell power output using hydrogenase anode and bilirubin oxidase cathode as the model system.