Intraoperative dexamethasone and chronic postsurgical pain: a propensity score-matched analysis of a large trial.

BACKGROUND: Dexamethasone has been shown to reduce acute pain after surgery, but there is uncertainty as to its effects on chronic postsurgical pain (CPSP). We hypothesised that in patients undergoing major noncardiac surgery, a single intraoperative dose of dexamethasone increases the incidence of CPSP. METHODS: We devised a propensity score-matched analysis of the ENIGMA-II trial CPSP dataset, aiming to compare the incidence of CPSP in patients who had received dexamethasone or not 12 months after major noncardiac surgery. The primary outcome was the incidence of CPSP. We used propensity score matching and inverse probability weighting to balance baseline variables to estimate the average marginal effect of dexamethasone on patient outcomes, accounting for confounding to estimate the average treatment effect on those treated with dexamethasone. RESULTS: We analysed 2999 patients, of whom 116 of 973 (11.9%) receiving dexamethasone reported CPSP, and 380 of 2026 (18.8%) not receiving dexamethasone reported CPSP, unadjusted odds ratio 0.76 (95% confidence interval 0.78-1.00), P=0.052. After propensity score matching, CPSP occurred in 116 of 973 patients (12.2%) receiving dexamethasone and 380 of 2026 patients (13.8%) not receiving dexamethasone, adjusted risk ratio 0.88 (95% confidence interval 0.61-1.27), P=0.493. There was no difference between groups in quality of life or pain interference with daily activities, but 'least pain' (P=0.033) and 'pain right now' (P=0.034) were higher in the dexamethasone group. CONCLUSIONS: Dexamethasone does not increase the risk of chronic postsurgical pain after major noncardiac surgery. CLINICAL TRIAL REGISTRATION: Open Science Framework Registration DOI https://doi.org/10.17605/OSF.IO/ZDVB5.

Inflammation risk before cardiac surgery and the treatment effect of intraoperative dexamethasone.

Patients who exhibit high systemic inflammation after cardiac surgery may benefit most from pre-emptive anti-inflammatory treatments. In this secondary analysis (n = 813) of the randomised, double-blind Intraoperative High-Dose Dexamethasone for Cardiac Surgery trial, we set out to develop an inflammation risk prediction model and assess whether patients at higher risk benefit from a single intraoperative dose of dexamethasone (1 mg/kg). Inflammation risk before surgery was quantified from a linear regression model developed in the placebo arm, relating preoperatively available covariates to peak postoperative C-reactive protein. The primary endpoint was the interaction between inflammation risk and the peak postoperative C-reactive protein reduction associated with dexamethasone treatment. The impact of dexamethasone on the main clinical outcome (a composite of death, myocardial infarction, stroke, renal failure, or respiratory failure within 30 days) was also explored in relation to inflammation risk. Preoperatively available covariates explained a minority of peak postoperative C-reactive protein variation and were not suitable for clinical application (R2 = 0.058, P = 0.012); C-reactive protein before surgery (excluded above 10 mg/L) was the most predictive covariate (P < 0.001). The anti-inflammatory effect of dexamethasone increased as the inflammation risk increased (-0.689 mg/L per unit predicted peak C-reactive protein, P = 0.002 for interaction). No treatment-effect heterogeneity was detected for the main clinical outcome (P = 0.167 for interaction). Overall, risk predictions from a model of inflammation after cardiac surgery were associated with the degree of peak postoperative C-reactive protein reduction derived from dexamethasone treatment. Future work should explore the impact of this phenomenon on clinical outcomes in larger surgical populations.

Serum lidocaine (lignocaine) concentrations during prolonged perioperative infusion in patients undergoing breast cancer surgery: A secondary analysis of a randomised controlled trial.

Perioperative lidocaine (lignocaine) infusions are being employed with increasing frequency. The determinants of systemic lidocaine concentrations during prolonged administration are unclear. In the Long-term Outcomes after Lidocaine Infusions for PostOperative Pain (LOLIPOP) pilot trial, the impact of infusion duration and body size metrics on serum lidocaine concentrations was examined with regression models in 48 women undergoing breast cancer surgery. Lidocaine was delivered as an intravenous bolus (1.5 mg/kg) and infusion (2 mg/kg per h) intraoperatively, followed by a 12-h subcutaneous infusion (1.33 mg/kg per h) postoperatively. Dosing was based on total body weight. Wound infiltration with other long-acting local anaesthetics was permitted. Protein binding and pharmacogenomic data were also collected. Lidocaine concentrations (median (interquartile range) (range)) during prolonged administration were in the safe and potentially therapeutic range: post-anaesthesia care unit 2.16 (1.73-2.82) (1.12-6.06) µg/ml; ward 1.41 (1.22-1.75) (0.64-2.81) µg/ml. Concentrations increased non-linearly during the early intravenous phase of administration (mean rise 1.21 µg/ml per hour of infusion, P = 0.007) but reached a pseudo steady-state during the later subcutaneous phase. Higher dose rates received per kilogram of lean (P = 0.004), adjusted (P = 0.006) and ideal body weight (P = 0.009) were associated with higher steady-state concentrations. The lidocaine free fraction was unaffected by the presence of ropivacaine, and phenotypes linked to slow metabolism were infrequent. Serum lidocaine concentrations reached a pseudo steady-state during a 12-h postoperative infusion. Greater precision in steady-state concentrations can be achieved by dosing on lean body weight versus adjusted or ideal body weight (equivalent lean body weight doses: intravenous bolus 2.5 mg/kg; intravenous infusion 3.33 mg/kg per h; subcutaneous infusion 2.22 mg/kg per h.

Variation in prescribing for the prevention of postoperative nausea, vomiting, and pain following abdominal surgery: A retrospective study.

Background and Aims: Adequate postoperative analgesia and prevention of post-op nausea and vomiting (PONV) are core components of modern day anaesthesia and peri-operative care. As well as contributing to overall morbidity, postoperative pain and PONV are frequently cited as one of the most unpleasant and distressing aspects of surgery for patients. Variation in healthcare delivery is known to exist but has often been poorly described. A first step to understanding the consequences of variation is to describe the extent of variation. We aimed to assess variation in pharmacological strategies to prevent postoperative pain, nausea and vomiting in patients undergoing elective major abdominal surgery at a tertiary hospital in Perth, Western Australia, over a three-month period. Methods: Retrospective cross-sectional study. Results: We observed considerable variation in prescribing of postoperative analgesia and PONV prophylaxis and suggest that despite adequate evidence based guidelines, they are often overlooked in practice. Conclusion: Measurement of the consequences of variation requires randomised clinical trials that evaluate differences in outcome and cost, associated with the strategies that exist within the spectrum of variation.

Dexamethasone and persistent wound pain: a prespecified analysis of the randomised Perioperative Administration of Dexamethasone and Infection (PADDI) trial.

BACKGROUND: Dexamethasone is commonly administered intraoperatively to prevent postoperative nausea and vomiting and is believed to have analgesic properties. It is unknown whether it has an impact on chronic wound pain. METHODS: In this prespecified embedded superiority substudy of the randomised PADDI trial, patients undergoing non-urgent noncardiac surgery received dexamethasone 8 mg or placebo intravenously after induction of anaesthesia, and were followed up for 6 months postoperatively. The primary outcome was the incidence of pain in the surgical wound at 6 months. Secondary outcomes included acute postoperative pain and correlates of chronic postsurgical pain. RESULTS: We included 8478 participants in the modified intention-to-treat population (4258 in the dexamethasone group and 4220 in the matched placebo group). The primary outcome occurred in 491 subjects (11.5%) in the dexamethasone arm and 404 (9.6%) subjects in the placebo arm (relative risk 1.2, 95% confidence interval 1.06-1.41, P=0.003). Maximum pain scores at rest and on movement in the first 3 postoperative days were lower in the dexamethasone group compared with the control group {median 5 (inter-quartile range [IQR] 3.0-8.0) vs 6 (IQR 3.0-8.0) and median 7 (IQR 5.0-9.0) vs 8 (IQR 6.0-9.0), P<0.001 for both}. Severity of postoperative pain was not predictive of chronic postsurgical pain. The severity of chronic postsurgical pain and the frequency of neuropathic features did not differ between treatment groups. CONCLUSION: Administration of dexamethasone 8 mg i.v. was associated with an increase in the risk of pain in the surgical wound 6 months after surgery. CLINICAL TRIAL REGISTRATION: ACTRN12614001226695.

Dexamethasone and clinically significant postoperative nausea and vomiting: a prespecified substudy of the randomised perioperative administration of dexamethasone and infection (PADDI) trial.

BACKGROUND: Clinically significant postoperative nausea and vomiting (PONV) is a patient-reported outcome which reflects patient experience. Although dexamethasone prevents PONV, it is unknown what impact it has on this experience. METHODS: In this prespecified embedded superiority substudy of the randomised Perioperative Administration of Dexamethasone and Infection (PADDI) trial, patients undergoing non-urgent noncardiac surgery received dexamethasone 8 mg or placebo intravenously after induction of anaesthesia, and completed a validated PONV questionnaire. The primary outcome was the incidence of clinically significant PONV on day 1 or day 2 postoperatively. Secondary outcomes included the incidence of clinically significant PONV and severe PONV on days 1 and 2 considered separately. RESULTS: A total of 1466 participants were included, with 733 patients allocated to the dexamethasone arm and 733 to matched placebo. The primary outcome occurred in 52 patients (7.1%) in the dexamethasone arm and 66 (9%) patients in the placebo arm (relative risk [RR]=0.79; 95% confidence interval [CI], 0.56-1.11; P=0.18). Severe PONV occurred on day 2 in 27 patients (3.9%) in the dexamethasone arm and 47 patients (6.7%) in the placebo arm (RR=0.58; 95% CI, 0.37-0.92; P=0.02; number needed-to-treat (NNT)=36.7; 95% CI, 20-202). In the entire cohort of 8880 PADDI patients, lower nausea scores, less frequent administration of antiemetics, and fewer vomiting events were recorded by patients in the dexamethasone arm up to day 2 after surgery. CONCLUSIONS: Administration of dexamethasone 8 mg i.v. did not influence clinically significant PONV. Dexamethasone administration did, however, decrease the incidence and severity of PONV, and was associated with less frequent administration of antiemetic agents. CLINICAL TRIAL REGISTRATION: ACTRN12614001226695.

Postoperative anaemia and patient-centred outcomes after major abdominal surgery: a retrospective cohort study.

BACKGROUND: Compared with anaemia before surgery, the underlying pathogenesis and implications of postoperative anaemia are largely unknown. METHODS: This retrospective cohort study analysed prospective data obtained from 2983 adult patients across 47 centres enrolled in a clinical trial evaluating restrictive and liberal intravenous fluids. The primary endpoint was persistent disability or death up to 90 days after surgery. Secondary endpoints included major septic complications, hospital stay, and patient quality of recovery using a 15-item quality of recovery (QoR-15) score, hospital re-admissions, and disability-free survival up to 12 months after surgery. Anaemia and disability were defined according to the WHO definitions. Multivariable regression was used to adjust for baseline risk and surgery. RESULTS: A total of 2983 patients met inclusion criteria for this study, of which 78.5% (95% confidence interval [CI], 76.7-80.1%) had postoperative anaemia. Patients with postoperative anaemia had a higher adjusted risk of death or disability up to 90 days after surgery when compared with those without anaemia: 18.2% vs 9.2% (risk ratio [RR]=1.51; 95% CI, 1.10-2.07, P=0.011); lower QoR-15 scores on Day 3 and Day 30, 105 (95% CI, 87-119) vs 114 (95% CI, 99-128; P<0.001), and 130 (95% CI, 112-140) vs 139 (95% CI, 121-144; P<0.011), respectively; higher adjusted risk of a composite of mortality/septic complications, 2.01 (95% CI, 1.55-42.67; P<0.001); unplanned admission to ICU (RR=2.65; 95% CI, 1.65-4.23; P<0.001); and longer median (inter-quartile range [IQR]) hospital stays, 6.6 (4.4-12.4) vs 3.7 (2.5-6.5) days (P<0.001). CONCLUSIONS: Postoperative anaemia is common and is independently associated with poor outcomes after surgery. Optimal prevention and treatment strategies need to be investigated. CLINICAL TRIAL REGISTRATION: NCT04978285 (ClinicalTrials.gov).

Inclusion, characteristics, and outcomes of male and female participants in large international perioperative studies.

BACKGROUND: We compared baseline characteristics and outcomes and evaluated the subgroup effects of randomised interventions by sex in males and females in large international perioperative trials. METHODS: Nine randomised trials and two cohort studies recruiting adult patients, conducted between 1995 and 2020, were included. Baseline characteristics and outcomes common to six or more studies were evaluated. Regression models included terms for sex, study, and an interaction between the two. Comparing outcomes without adjustment for baseline characteristics represents the 'total effect' of sex on the outcome. RESULTS: Of 54 626 participants, 58% were male and 42% were female. Females were less likely to have ASA physical status ≥3 (56% vs 64%), to smoke (15% vs 23%), have coronary artery disease (21% vs 32%), or undergo vascular surgery (10% vs 23%). The pooled incidence of death was 1.6% in females and 1.8% in males (risk ratio [RR] 0.92; 95% confidence interval [CI]: 0.81-1.05; P=0.20), of myocardial infarction was 4.2% vs 4.5% (RR 0.92; 95% CI: 0.81-1.03; P=0.10), of stroke was 0.5% vs 0.6% (RR 1.03; 95% CI: 0.79-1.35; P=0.81), and of surgical site infection was 8.6% vs 8.3% (RR 1.03; 95% CI: 0.79-1.35; P=0.70). Treatment effects of three interventions demonstrated statistically significant effect modification by sex. CONCLUSIONS: Females were in the minority in all included studies. They were healthier than males, but outcomes were comparable. Further research is needed to understand the reasons for this discrepancy. CLINICAL TRIAL REGISTRATION: International Registry of Meta-Research (UID: IRMR_000011; 5 January 2021).

External validity of four risk scores predicting 30-day mortality after surgery.

Background: Surgical risk prediction tools can facilitate shared decision-making and efficient allocation of perioperative resources. Such tools should be externally validated in target populations before implementation. Methods: Predicted risk of 30-day mortality was retrospectively derived for surgical patients at Royal Perth Hospital from 2014 to 2021 using the Surgical Outcome Risk Tool (SORT) and the related NZRISK (n=44 031, 53 395 operations). In a sub-population (n=31 153), the Physiology and Operative Severity Score for the enumeration of Mortality (POSSUM) and the Portsmouth variant of this (P-POSSUM) were matched from the Copeland Risk Adjusted Barometer (C2-Ai, Cambridge, UK). The primary outcome was risk score discrimination of 30-day mortality as evaluated by area-under-receiver operator characteristic curve (AUROC) statistics. Calibration plots and outcomes according to risk decile and time were also explored. Results: All four risk scores showed high discrimination (AUROC) for 30-day mortality (SORT=0.922, NZRISK=0.909, P-POSSUM=0.893; POSSUM=0.881) but consistently over-predicted risk. SORT exhibited the best discrimination and calibration. Thresholds to denote the highest and second-highest deciles of SORT risk (>3.92% and 1.52-3.92%) captured the majority of deaths (76% and 13%, respectively) and hospital-acquired complications. Year-on-year SORT calibration performance drifted towards over-prediction, reflecting a decrease in 30-day mortality over time despite an increase in the surgical population risk. Conclusions: SORT was the best performing risk score in predicting 30-day mortality after surgery. Categorising patients based on SORT into low, medium (80-90th percentile), and high risk (90-100th percentile) might guide future allocation of perioperative resources. No tools were sufficiently calibrated to support shared decision-making based on absolute predictions of risk.

Dexamethasone and Surgical-Site Infection.

BACKGROUND: The glucocorticoid dexamethasone prevents nausea and vomiting after surgery, but there is concern that it may increase the risk of surgical-site infection. METHODS: In this pragmatic, international, noninferiority trial, we randomly assigned 8880 adult patients who were undergoing nonurgent, noncardiac surgery of at least 2 hours' duration, with a skin incision length longer than 5 cm and a postoperative overnight hospital stay, to receive 8 mg of intravenous dexamethasone or matching placebo while under anesthesia. Randomization was stratified according to diabetes status and trial center. The primary outcome was surgical-site infection within 30 days after surgery. The prespecified noninferiority margin was 2.0 percentage points. RESULTS: A total of 8725 participants were included in the modified intention-to-treat population (4372 in the dexamethasone group and 4353 in the placebo group), of whom 13.2% (576 in the dexamethasone group and 572 in the placebo group) had diabetes mellitus. Of the 8678 patients included in the primary analysis, surgical-site infection occurred in 8.1% (354 of 4350 patients) assigned to dexamethasone and in 9.1% (394 of 4328) assigned to placebo (risk difference adjusted for diabetes status, -0.9 percentage points; 95.6% confidence interval [CI], -2.1 to 0.3; P<0.001 for noninferiority). The results for superficial, deep, and organ-space surgical-site infections and in patients with diabetes were similar to those of the primary analysis. Postoperative nausea and vomiting in the first 24 hours after surgery occurred in 42.2% of patients in the dexamethasone group and in 53.9% in the placebo group (risk ratio, 0.78; 95% CI, 0.75 to 0.82). Hyperglycemic events in patients without diabetes occurred in 22 of 3787 (0.6%) in the dexamethasone group and in 6 of 3776 (0.2%) in the placebo group. CONCLUSIONS: Dexamethasone was noninferior to placebo with respect to the incidence of surgical-site infection within 30 days after nonurgent, noncardiac surgery. (Funded by the Australian National Health and Medical Research Council and others; PADDI Australian New Zealand Clinical Trials Registry number, ACTRN12614001226695.).

Increased inspired oxygen concentration does not adversely affect oxidative stress and the resolution of inflammation during reperfusion in patients undergoing knee replacement surgery.

The level of inspired oxygen during surgery may modify free radical release, and reperfusion injury. This controlled trial examined the effect of inspired oxygen on F2-isoprostanes (F2-IsoPs), isofurans (IsoFs), and specialized mediators of inflammation resolution (SPM) during knee replacement surgery. Patients received either 30% O2 (control n = 21), 50% O2 (n = 20), or 80% O2 (n = 19) O2, in a parallel design. Hemoglobin (Hb) was measured throughout the surgery and F2-IsoPs, IsoFs and SPM were analyzed by mass spectrometry. The effect of O2 on F2-IsoPs and IsoFs was examined during tourniquet inflation and after tourniquet release. SPM were measured at baseline and the end of surgery. There was a significant interaction between O2 and Hb concentrations with plasma IsoFs during tourniquet inflation. An increase in plasma IsoFs over time was attenuated in the 80% O2 group (p=.012) compared with the 30% O2 group after adjusting for Hb concentration. After tourniquet release, plasma F2-IsoPs were significantly lower in the 50% and 80% O2 groups (p=.009 and p=.001, respectively) compared with the 30% O2 group after adjustment for Hb concentration. The SPM RvD2 and RvE2 were increased with 50% and 80% O2 (RvD2, p=.014 and p=.002, respectively; RvE2, p=.032 with 50% O2) compared with the 30% O2 group, in analyses that corrected for Hb concentration. We have shown for the first time that higher O2 levels may be beneficial in reducing oxidative stress and increasing resolution of inflammation during surgery that involves reperfusion after application of a tourniquet.

Perioperative ADministration of Dexamethasone And blood Glucose concentrations in patients undergoing elective non-cardiac surgery - the randomised controlled PADDAG trial.

BACKGROUND: The hyperglycaemic effect of dexamethasone in diabetic and nondiabetic patients in the peri-operative period is unknown. OBJECTIVE: To assess the effect of a single dose of intra-operative dexamethasone on peri-operative blood glucose. DESIGN: Multicentre, stratified, randomised trial. SETTING: University hospitals in Australia and Hong Kong. PATIENTS: A total of 302 adults scheduled for elective, noncardiac and nonobstetric surgical procedures under general anaesthesia, stratified by diabetes mellitus status, were randomised to receive placebo, 4 or 8 mg dexamethasone administered intravenously after induction of anaesthesia. MAIN OUTCOME MEASURES: Maximum blood glucose within 24 h of surgery, and the interaction between glycated haemoglobin (HbA1c) and dexamethasone were the primary and secondary outcomes. RESULTS: The median [IQR] baseline blood glucose in the nondiabetes stratum in the placebo (n=81), 4 mg (n=81) and 8 mg dexamethasone (n=77) trial arms were respectively 5.3 [4.6 to 5.8], 5.0 [4.7 to 5.4] and 5.0 [4.2 to 5.9] mmol l-1. In the diabetes stratum these values were 6.6 [6.0 to 8.3]; (n=22), 6.1 [5.5 to 10.4]; (n=22) and 6.7 [5.6 to 8.3]; (n=19) mmol l-1. The median [IQR] maximum peri-operative blood glucose values in the nondiabetes stratum were 6.0 [5.3 to 6.8], 6.3 [5.5 to 7.3] and 6.3 [5.8 to 7.4] mmol l-1 in the control, dexamethasone 4 mg and dexamethasone 8 mg arms, respectively. In the diabetes stratum these values were 10.3 [8.1 to 12.4], 12.6 [10.3 to 18.3] and 13.6 [11.2 to 20.1] mmol l-1. There was a significant interaction between pre-operative HbA1c value and 8 mg dexamethasone: every 1% increment in HbA1c produced a 4.0 mmol l-1 elevation in maximal peri-operative glucose concentration. CONCLUSION: Dexamethasone 4 mg or 8 mg did not induce greater hyperglycaemia compared with placebo for nondiabetic and well controlled diabetic patients. Maximal peri-operative blood glucose concentrations in patients with diabetes were related to baseline HbA1c values in a concentration-dependent fashion after 8 mg of dexamethasone. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Registry (ACTRN12614001145695): URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367272.

Anaesthetic depth and complications after major surgery: an international, randomised controlled trial.

BACKGROUND: An association between increasing anaesthetic depth and decreased postoperative survival has been shown in observational studies; however, evidence from randomised controlled trials is lacking. Our aim was to compare all-cause 1-year mortality in older patients having major surgery and randomly assigned to light or deep general anaesthesia. METHODS: In an international trial, we recruited patients from 73 centres in seven countries who were aged 60 years and older, with significant comorbidity, having surgery with expected duration of more than 2 h, and an anticipated hospital stay of at least 2 days. We randomly assigned patients who had increased risk of complications after major surgery to receive light general anaesthesia (bispectral index [BIS] target 50) or deep general anaesthesia (BIS target 35). Anaesthetists also nominated an appropriate range for mean arterial pressure for each patient during surgery. Patients were randomly assigned in permuted blocks by region immediately before surgery, with the patient and assessors masked to group allocation. The primary outcome was 1-year all-cause mortality. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000632897, and is closed to accrual. FINDINGS: Patients were enrolled between Dec 19, 2012, and Dec 12, 2017. Of the 18 026 patients screened as eligible, 6644 were enrolled, randomly assigned to treatment or control, and formed the intention-to-treat population (3316 in the BIS 50 group and 3328 in the BIS 35 group). The median BIS was 47·2 (IQR 43·7 to 50·5) in the BIS 50 group and 38·8 (36·3 to 42·4) in the BIS 35 group. Mean arterial pressure was 3·5 mm Hg (4%) higher (median 84·5 [IQR 78·0 to 91·3] and 81·0 [75·4 to 87·6], respectively) and volatile anaesthetic use was 0·26 minimum alveolar concentration (30%) lower (0·62 [0·52 to 0·73] and 0·88 [0·74 to 1·04], respectively) in the BIS 50 than the BIS 35 group. 1-year mortality was 6·5% (212 patients) in the BIS 50 group and 7·2% (238 patients) in the BIS 35 group (hazard ratio 0·88, 95% CI 0·73 to 1·07, absolute risk reduction 0·8%, 95% CI -0·5 to 2·0). Grade 3 adverse events occurred in 954 (29%) patients in the BIS 50 group and 909 (27%) patients in the BIS 35 group; and grade 4 adverse events in 265 (8%) and 259 (8%) patients, respectively. The most commonly reported adverse events were infections, vascular disorders, cardiac disorders, and neoplasms. INTERPRETATION: Among patients at increased risk of complications after major surgery, light general anaesthesia was not associated with lower 1-year mortality than deep general anaesthesia. Our trial defines a broad range of anaesthetic depth over which anaesthesia may be safely delivered when titrating volatile anaesthetic concentrations using a processed electroencephalographic monitor. FUNDING: Health Research Council of New Zealand; National Health and Medical Research Council, Australia; Research Grant Council of Hong Kong; National Institute for Health and Research, UK; and National Institutes of Health, USA.

The perioperative administration of dexamethasone and infection (PADDI) trial protocol: rationale and design of a pragmatic multicentre non-inferiority study.

INTRODUCTION: The intraoperative administration of dexamethasone for prophylaxis against postoperative nausea and vomiting is a common and recommended practice. The safety of the administration of this immunosuppressive agent at a time of significant immunological disruption has not been rigorously evaluated in terms of infective complications. METHODS/ANALYSIS: This is a pragmatic, multicentre, randomised, controlled, non-inferiority trial. A total of 8880 patients undergoing elective major surgery will be enrolled. Participants will be randomly allocated to receive either dexamethasone 8 mg or placebo intravenously following the induction of anaesthesia in a 1:1 ratio, stratified by centre and diabetes status. Patient enrolment into the trial is ongoing. The primary outcome is surgical site infection at 30 days following surgery, defined according to the Centre for Disease Control criteria. ETHICS/DISSEMINATION: The PADDI trial has been approved by the ethics committees of over 45 participating sites in Australia, New Zealand, Hong Kong, South Africa and the Netherlands. The trial has been endorsed by the Australia and New Zealand College of Anaesthetists Clinical Trials Network and the Australian Society for Infectious Diseases Clinical Research Network. Participant recruitment began in March 2016 and is expected to be complete in mid-2019. Publication of the results of the PADDI trial is anticipated to occur in early 2020. TRIAL REGISTRATION NUMBER: ACTRN12614001226695.

Antiemetic doses of dexamethasone and their effects on immune cell populations and plasma mediators of inflammation resolution in healthy volunteers.

INTRODUCTION: The synthetic glucocorticoid dexamethasone is a commonly administered antiemetic. It has immunosuppressive effects and may alter postoperative blood glucose concentrations. Dexamethasone can effect key enzymes involved in inflammation resolution that is an active process driven by specialised lipid mediators of inflammation resolution (SPM). The purpose of this study in healthy volunteers was to examine whether dexamethasone effects cell populations and synthesis of SPM that are critical for the resolution of inflammation. METHODS: Thirty-two healthy volunteers were randomly allocated to receive saline (Control) or dexamethasone 2 mg, 4 mg or 8 mg intravenously. Venous blood samples were collected at baseline before administration of treatment, and at 4 h, 24 h and one-week post-treatment. At each time point, measurements included blood glucose and macrophage migration inhibition factor (MMIF), full blood count including lymphocyte subsets, monocytes, neutrophils, eosinophils and basophils by flow cytometry, and plasma SPM using liquid chromatography tandem mass spectrometry. The effect of dexamethasone dose and time on all measures was analysed using linear mixed models. RESULTS: There was a dose-dependent increase in neutrophil count after dexamethasone that persisted for 24 h. In contrast, there was a dose-dependent reduction in counts of monocytes, lymphocytes, basophils and eosinophils 4 h after dexamethasone, followed by a rebound increase in cell counts at 24 h. Seven days after administration of dexamethasone, all cell counts were similar to baseline levels. MMIF concentration, glucose and natural killer cell counts were not significantly affected by dexamethasone. There was a significant gender effect on plasma SPM such that levels of 17-HDHA, RvD1, 17R-RvD1 and RvE2 in females were on average 14%-50% lower than males. In a linear mixed model that adjusted for neutrophil count, there was a significant interaction between the dose of dexamethasone and time, on plasma 17R-RvD1 such that plasma 17R-RvD1 fell in a dose-dependent manner until 4 h after administration of dexamethasone. There were no significant effects of dexamethasone on the other plasma SPM (18-HEPE, RvE2, 17-HDHA, RvD1, RvD2 and 14-HDHA) measured. DISCUSSION: This is the first study in healthy volunteers to demonstrate that commonly employed antiemetic doses of dexamethasone affect immune cell populations and plasma levels of 17R-RvD1 an SPM with anti-nociceptive properties. If similar changes occur in surgical patients, then this may have implications for acute infection risk in the post-operative period.

Safety of Perioperative Glucocorticoids in Elective Noncardiac Surgery: A Systematic Review and Meta-analysis.

BACKGROUND: Glucocorticoids are increasingly used perioperatively, principally to prevent nausea and vomiting. Safety concerns focus on the potential for hyperglycemia and increased infection. The authors hypothesized that glucocorticoids predispose to such adverse outcomes in a dose-dependent fashion after elective noncardiac surgery. METHODS: The authors conducted a systematic literature search of the major medical databases from their inception to April 2016. Randomized glucocorticoid trials in adults specifically reporting on a safety outcome were included and meta-analyzed with Peto odds ratio method or the quality effects model. Subanalyses were performed according to a dexamethasone dose equivalent of low (less than 8 mg), medium (8 to 16 mg), and high (more than 16 mg). The primary endpoints of any wound infection and peak perioperative glucose concentrations were subject to meta-regression. RESULTS: Fifty-six trials from 18 countries were identified, predominantly assessing dexamethasone. Glucocorticoids did not impact on any wound infection (odds ratio, 0.8; 95% CI, 0.6 to 1.2) but did result in a clinically unimportant increase in peak perioperative glucose concentration (weighted mean difference, 20.0 mg/dl; CI, 11.4 to 28.6; P < 0.001 or 1.1 mM; CI, 0.6 to 1.6). Glucocorticoids reduced peak postoperative C-reactive protein concentrations (weighted mean difference, -22.1 mg/l; CI, -31.7 to -12.5; P < 0.001), but other adverse outcomes and length of stay were unchanged. No dose-effect relationships were apparent. CONCLUSIONS: The evidence at present does not highlight any safety concerns with respect to the use of perioperative glucocorticoids and subsequent infection, hyperglycemia, or other adverse outcomes. Nevertheless, collated trials lacked sufficient surveillance and power to detect clinically important differences in complications such as wound infection.

Does Furosemide Increase Oxidative Stress in Acute Kidney Injury?

Furosemide, a loop diuretic, is used to increase urine output in patients with acute kidney injury (AKI). It remains uncertain whether the benefits of furosemide in AKI outweigh its potential harms. We investigated if furosemide influenced oxidative stress in 30 critically ill patients with AKI by measuring changes in F2-isoprostanes (F2-IsoPs), markers of in vivo oxidative stress, in plasma and urine following intravenous furosemide. Urine F2-IsoPs were higher in sepsis (p = 0.001) and increased in proportion to urine furosemide (p = 0.001). The furosemide-induced increase in urine F2-IsoPs differed depending on AKI severity (p < 0.001) and was greatest in those with the most severe AKI. Furosemide had no effect on plasma F2-IsoPs. We demonstrate for the first time that furosemide increases renal oxidative stress in AKI and find that patients with the most severe AKI-to whom the largest doses are likely to be administered-showed the greatest increase in oxidative stress. These findings lead to the hypothesis that the common practice of administering high-dose furosemide to convert oliguric to nonoliguric AKI may induce harmful oxidative stress in the kidneys, and an adequately powered, randomized controlled trial is required to determine if clinical benefits of this dosing strategy justify its potential harms. Antioxid. Redox Signal. 26, 221-226.

Controlled moderate hypovolaemia in healthy volunteers is not associated with the development of oxidative stress assessed by plasma F2-isoprostanes and isofurans.

Hypovolaemia can be associated with substantial morbidity, particularly when it occurs in the setting of trauma and in patients with comorbid diseases. Hypovolaemia and inflammation such as occur in the setting of trauma and surgery, are associated with systemic oxidative stress and free-radical injury. Free-radical injury that results from hypovolaemia-induced organ reperfusion may further augment inflammatory processes. It is unknown exactly what proportion of free-radical injury is associated with isolated hypovolaemia as opposed to the contribution from inflammation from surgery or trauma. In the first human study of its kind, we exposed 8 adult male volunteers to venesection-induced hypovolaemia in progressive aliquots of 5% of total blood volume until 20% had been removed. This blood was subsequently reinfused. Plasma F2-isoprostanes and isofurans, markers of in vivo lipid oxidation, were measured by gas chromatography-mass spectrometry at each 5% aliquot venesected and at each 5% reinfused. Between baseline and maximal blood loss there was a minor fall in haemoglobin concentration from 143.9g/l to 138.8g/l (p=0.004, 95% CI 2.2, 8.0g/L). No significant change from baseline occurred in the concentrations of either plasma F2-isoprostanes or isofurans during venesection (p=0.116 and p=0.152, respectively) or blood reinfusion (p=0.553 and p=0.736, respectively). We can conclude that in healthy adult volunteers, isolated hypovolaemia to 20% total blood volume loss is not associated with detectable systemic oxidative stress. The free-radical injury identified in surgical and trauma patients may represent the effects of tissue damage and inflammation, with an uncertain contribution from tissue ischemia as may occur with hypovolaemia.

Determinants of Urinary Output Response to IV Furosemide in Acute Kidney Injury: A Pharmacokinetic/Pharmacodynamic Study.

OBJECTIVES: This study assessed the determinants of urinary output response to furosemide in acute kidney injury; specifically, whether the response is related to altered pharmacokinetics or pharmacodynamics. DESIGN: Prospective cohort. SETTING: Tertiary ICU. PATIENTS: Thirty critically ill patients with acute kidney injury without preexisting renal impairment or recent diuretic exposure. INTERVENTION: A single dose of IV furosemide. MEASUREMENTS AND MAIN RESULTS: Baseline markers of intravascular volume status were obtained prior to administering furosemide. Six-hour creatinine clearance, hourly plasma/urinary furosemide concentrations, and hourly urinary output were used to assess furosemide pharmacokinetics/pharmacodynamics parameters. Of 30 patients enrolled, 11 had stage-1 (37%), nine had stage-2 (30%), and 10 had stage-3 (33%) Acute Kidney Injury Network acute kidney injury. Seventy-three percent were septic, 47% required norepinephrine, and 53% were mechanically ventilated. Urinary output doubled in 20 patients (67%) following IV furosemide. Measured creatinine clearance was strongly associated with the amount of urinary furosemide excreted and was the only reliable predictor of the urinary output after furosemide (area under the receiver-operating-characteristic curve, 0.75; 95% CI, 0.57-0.93). In addition to an altered pharmacokinetics (p < 0.01), a reduced pharmacodynamics response to furosemide also became important when creatinine clearance was reduced to less than 40 mL/min/1.73 m (p = 0.01). Acute kidney injury staging and markers of intravascular volume, including central venous pressure, brain-natriuretic-peptide concentration, and fractional urinary sodium excretion were not predictive of urinary output response to furosemide. CONCLUSIONS: The severity of acute kidney injury, as reflected by the measured creatinine clearance, alters both pharmacokinetics and pharmacodynamics of furosemide in acute kidney injury, and was the only reliable predictor of the urinary output response to furosemide in acute kidney injury.