Comparative simulation of intraperitoneal aminoglycoside regimens for patients with peritonitis on automated peritoneal dialysis.

BACKGROUND: Intraperitoneal (IP) aminoglycosides (AGs) continue to be the cornerstone of empiric management of peritonitis. AG dosing during automated peritoneal dialysis (APD), however, has not been well studied in patients with peritonitis. We sought to identify differences in AG exposure in the peritoneum and plasma for two different dosing regimens with little supporting evidence in patients on APD with peritonitis. METHODS: A retrospective design that utilised the peritoneal and plasma concentration-time data from a prior study of 18 continuous ambulatory peritoneal dialysis (CAPD) patients with peritonitis to generate an in silico peritoneal and plasma PK model. This model was then used to compare via simulation using Phoenix© WinNonlin Software with IP AG dosing for a loading-dose regimen (1.5 mg/kg first dose) versus a fixed-dose regimen (0.6 mg/kg/d) in patients on APD with peritonitis. RESULTS: Outcome measures were (1) percentage of time where peritoneal peak concentrations/minimal inhibitory concentration (MIC) ratio >10, (2) AUC/MIC > 74 and (3) plasma Cmin concentrations. Both regimens resulted in > 90% optimal peak/MIC ratio and AUC/MIC ratios on days 1 and 5 of the dose protocol. The loading-dose regimen resulted in IP exposures that were 2.5 times greater in the peritoneal compartment on day 1. By day 5, both protocols resulted in similar accumulation of AG plasma Cmin concentrations of 2.5-3.4 mg/L versus 2.4-3.3 mg/L, respectively, for the loading-dose regimen versus fixed-dose regimen. CONCLUSIONS: The current international guidelines for the treatment of peritoneal dialysis-associated peritonitis can continue to recommend the fixed-dose regimen for those on APD with the addition of plasma Cmin monitoring after 3 days to assess for drug accumulation.

An updated vancomycin dosing protocol for initiating therapy in patients undergoing intermittent high-flux hemodialysis.

PURPOSE: To design an updated vancomycin dosing protocol for initiating therapy in patients undergoing chronic intermittent high-flux hemodialysis (iHFHD) that is congruent with the revised 2020 consensus guidelines for therapeutic drug monitoring (TDM). METHODS: Monte Carlo simulation methods were used to study vancomycin dosing for patients on iHFHD. Vancomycin regimens were constructed as intravenous infusions (for intradialytic administration) of a loading dose and maintenance doses 3 times weekly during subsequent dialysis sessions. Vancomycin plasma concentrations were simulated, and the probability of target attainment (PTA) for a 24-hour area under the time-concentration curve (AUC24) of 400 to 700 mg · h/L was determined. Standardized weight-based (ie, dose-banding) regimens were investigated, and an optimized protocol was selected based on TDM target attainment and practical considerations for use in the dialysis setting. RESULTS: The proposed vancomycin dosing protocol (for intradialytic administration) specifies 3 regimens: (1) a 1,500-mg loading dose and 750-mg maintenance doses for patients weighing 50 kg to 69 kg; (2) a 2,000-mg loading dose and 1,000-mg maintenance doses for patients weighing 70 kg to 89 kg; and (3) a 2,500-mg loading dose and 1,250-mg maintenance doses for patients weighing 90 kg to 110 kg. In a simulated hemodialysis population (n = 5,000), the proposed protocol delivered median (interquartile range [IQR]) loading and maintenance doses of 25.0 (23.4-26.6) mg/kg and 12.5 (11.8-13.3) mg/kg, respectively. The PTA for an AUC24 of 400 to 700 mg · h/L was 74.7% on day 1 and 70.8% on day 8, with less than 10% of values exceeding the target range. CONCLUSION: Our proposed dosing protocol for patients undergoing iHFHD offers an updated and practical approach for initiating vancomycin therapy that can be optimized with early TDM.

Prophylactic tranexamic acid use in non-cardiac surgeries at high risk for transfusion.

BACKGROUND: Tranexamic acid (TXA) reduces transfusion in a wide range of surgical populations, although its real-world use in non-cardiac surgeries has not been well described. The objective of this study was to describe prophylactic TXA use in non-cardiac surgeries at high risk for transfusion. METHODS: This is a retrospective cohort study of all adult patients undergoing major non-cardiac surgery at ≥5% risk of perioperative transfusion at five Canadian hospitals between January 2014 and December 2016. Canadian Classification of Health Interventions procedure codes within the Discharge Abstract Database were linked to transfusion and laboratory databases. TXA use was ascertained electronically from The Ottawa Hospital Data Warehouse and via manual chart review for Winnipeg hospitals. For each surgery, we evaluated the percentage of patients who received TXA as well as the specifics of TXA dosing and administration. RESULTS: TXA use was evaluable in 14 300 patients. Overall, 17% of surgeries received TXA, ranging from 0% to 68% among individual surgeries. TXA use was more common in orthopaedic (n = 2043/4942; 41%) and spine surgeries (n = 239/1322; 18%) compared to other surgical domains (n = 109/8036; 1%). TXA was commonly administered as a bolus (n = 2097/2391; 88%). The median TXA dose was 1000 mg (IQR 1000-1000 mg). CONCLUSION: TXA is predominantly used in orthopaedic and spine surgeries, with little uptake in other non-cardiac surgeries at high risk for red blood cell transfusion. Further studies are needed to evaluate the effectiveness and safety of TXA and to understand the barriers to TXA administration in a broad range of non-cardiac surgeries.

Real-life experience with ceftolozane/tazobactam in Canada: results from the CLEAR (Canadian LEadership on Antimicrobial Real-life usage) registry.

OBJECTIVES: Ceftolozane/tazobactam is a cephalosporin/ß-lactamase inhibitor combination with activity against Gram-negative bacilli. Here we report the use of ceftolozane/tazobactam in Canada using a national registry. METHODS: The CLEAR registry uses a REDCapTM online survey to capture details associated with clinical use of ceftolozane/tazobactam. RESULTS: Data from 51 patients treated in 2020 with ceftolozane/tazobactam are available. Infections treated included hospital-acquired bacterial pneumonia (37.3% of patients), ventilator-associated bacterial pneumonia (15.7%), bone and joint infection (11.8%), complicated intra-abdominal infection (7.8%) and complicated skin and skin-structure infection (7.8%). Moreover, 17.6% of patients had bacteraemia and 47.1% were in intensive care. Ceftolozane/tazobactam was primarily used as directed therapy for Pseudomonas aeruginosa infections (92.2% of patients). Ceftolozane/tazobactam was used because of resistance to (86.3%), failure of (11.8%) or adverse effects from (2.0%) previously prescribed antimicrobials. Ceftolozane/tazobactam susceptibility testing was performed on isolates from 88.2% of patients. Ceftolozane/tazobactam was used in combination with another antimicrobial active against Gram-negative bacilli in 39.2% of patients [aminoglycosides (15.7%), fluoroquinolones (9.8%) and colistin/polymyxin B (7.8%)]. The dosage regimen was customised in all patients based on creatinine clearance. The treatment duration was primarily >10 days (60.8% of patients), with microbiological success in 60.5% and clinical success in 64.4% of patients. Moreover, 7.8% of patients had adverse effects not requiring drug discontinuation. CONCLUSION: In Canada, ceftolozane/tazobactam is used as directed therapy to treat a variety of severe infections caused by multidrug-resistant P. aeruginosa. It is commonly used in combination with other antimicrobials with relatively high microbiological/clinical cure rates and an excellent safety profile.

Variation in prophylactic tranexamic acid administration among anesthesiologists and surgeons in orthopedic surgery: a retrospective cohort study.

PURPOSE: Tranexamic acid (TXA) reduces red blood cell transfusion in various orthopedic surgeries, yet the degree of practice variation in its use among anesthesiologists and surgeons has not been described. To target future knowledge transfer and implementation strategies, and to better understand determinants of variability in prophylactic TXA use, our primary objective was to evaluate the influence of surgical team members on the variability of prophylactic TXA administration. METHODS: This was a retrospective cohort study of all adult patients undergoing primary total hip arthroplasty (THA), hip fracture surgery, and spine fusion ± vertebrectomy at two Canadian hospitals between January 2014 and December 2016. We used Canadian Classification of Health Interventions procedure codes within the Discharge Abstract Database which we linked to the Ottawa Data Warehouse. We described the percentage of patients that received TXA by individual surgery, the specifics of TXA dosing, and estimated the effect of anesthesiologists and surgeons on prophylactic TXA using multivariable mixed-effects logistic regression analyses. RESULTS: In the 3,900 patients studied, TXA was most commonly used in primary THA (85%; n = 1,344/1,582), with lower use in hip fracture (23%; n = 342/1,506) and spine fusion surgery (23%; n = 186/812). The median [interquartile range] total TXA dose was 1,000 [1,000-1,000] mg, given as a bolus in 92% of cases. Anesthesiologists and surgeons added significant variability to the odds of receiving TXA in hip fracture surgery and spine fusion, but not primary THA. Most of the variability in TXA use was attributed to patient and other factors. CONCLUSION: We confirmed the routine use of TXA in primary THA, while observing lower utilization with more variability in hip fracture and spine fusion surgery. Further study is warranted to understand variations in use and the barriers to TXA implementation in a broader population of orthopedic surgical patients at high risk for transfusion.

RéSUMé: OBJECTIF: L'acide tranexamique (ATX) réduit la transfusion d'érythrocytes dans diverses chirurgies orthopédiques. Cependant, les variations de pratique quant à son utilisation parmi les anesthésiologistes et les chirurgiens n'ont pas été décrites. Afin de cibler les stratégies futures de transfert des connaissances et de mise en œuvre, et pour mieux comprendre les déterminants de la variabilité dans l'utilisation prophylactique d'ATX, notre objectif principal était d'évaluer l'influence des membres de l'équipe chirurgicale sur la variabilité de l'administration prophylactique d'ATX. MéTHODE: Il s'agissait d'une étude de cohorte rétrospective de tous les patients adultes subissant une arthroplastie totale primaire de la hanche (ATH), une chirurgie de fracture de la hanche et une fusion intervertébrale ± vertébrectomie dans deux hôpitaux canadiens entre janvier 2014 et décembre 2016. Nous avons utilisé les codes de procédure de la Classification canadienne des interventions en santé dans la Base de données sur les congés des patients, que nous avons liée à la banque de données d'Ottawa. Nous avons décrit le pourcentage de patients qui ont reçu de l'ATX par chirurgie individuelle, les détails du dosage de l'ATX, et avons estimé l'effet des anesthésiologistes et des chirurgiens sur l'ATX prophylactique en réalisant des analyses de régression logistique multivariées à effets mixtes. RéSULTATS: Parmi les 3900 patients étudiés, l'ATX était le plus fréquemment utilisé lors d'une ATH primaire (85 %; n = 1344/1582), avec une utilisation plus faible lors de chirurgie de fracture de la hanche (23 %; n = 342/1506) et de chirurgie de fusion intervertébrale (23 %; n = 186/812). La dose totale médiane [écart interquartile] d'ATX était de 1000 mg [1000 à 1000], administrés dans 92 % des cas sous forme de bolus. Les anesthésiologistes et les chirurgiens ont ajouté une variabilité significative aux probabilités de recevoir de l'ATX lors d'une chirurgie de fracture de la hanche et de fusion, mais pas lors d'ATH primaire. La majeure partie de la variabilité dans l'utilisation d'ATX était attribuable aux facteurs liés au patient et à d'autres facteurs. CONCLUSION: Nous avons confirmé l'utilisation de routine de l'ATX dans l'ATH primaire, tout en observant une utilisation moins répandue et plus variable lors de chirurgie de fracture de la hanche et de fusion intervertébrale. Une étude plus approfondie est nécessaire pour comprendre les variations d'utilisation et les obstacles à la mise en œuvre de l'ATX dans une population plus étendue de patients de chirurgie orthopédique à haut risque de transfusion.

Evaluation of Transfusion Practices in Noncardiac Surgeries at High Risk for Red Blood Cell Transfusion: A Retrospective Cohort Study.

Perioperative bleeding is a major indication for red blood cell (RBC) transfusion, yet transfusion data in many major noncardiac surgeries are lacking and do not reflect recent blood conservation efforts. We aim to describe transfusion practices in noncardiac surgeries at high risk for RBC transfusion. We completed a retrospective cohort study to evaluate adult patients undergoing major noncardiac surgery at 5 Canadian hospitals between January 2014 and December 2016. We used Canadian Classification of Health Interventions procedure codes within the Discharge Abstract Database, which we linked to transfusion and laboratory databases. We studied all patients undergoing a major noncardiac surgery at ≥5% risk of perioperative RBC transfusion. For each surgery, we characterized the percentage of patients exposed to an RBC transfusion, the mean/median number of RBC units transfused, and platelet and plasma exposure. We identified 85 noncardiac surgeries with an RBC transfusion rate ≥5%, representing 25,607 patient admissions. The baseline RBC transfusion rate was 16%, ranging from 5% to 49% among individual surgeries. Of those transfused, the median (Q1, Q3) number of RBCs transfused was 2 U (1, 3 U); 39% received 1 U RBC, 36% received 2 U RBC, and 8% were transfused ≥5 U RBC. Platelet and plasma transfusions were overall low. In the era of blood conservation, we described transfusion practices in major noncardiac surgeries at high risk for RBC transfusion, which has implications for patient consent, preoperative surgical planning, and blood bank inventory management.

Clinical Blood Isolates from Hemodialysis Patients: Distribution of Organisms and Antimicrobial Resistance, 2007-2014.

BACKGROUND: Given the morbidity and mortality associated with bloodstream infections in hemodialysis patients, understanding the microbiology is essential to optimizing treatment in this high-risk population. OBJECTIVES: To conduct a retrospective surveillance study of clinical blood isolates from adult hemodialysis patients, and to predict the microbiological coverage of empiric therapies for bloodstream infections in this population. METHODS: Clinical blood isolate data were collected from the 4 main outpatient hemodialysis units in Winnipeg, Manitoba, from 2007 to 2014. The distribution of organisms and antimicrobial susceptibilities were characterized. When appropriate, changes over time were tested using time series analysis. Study data were used to predict and compare the microbiological coverage of various empiric therapies for bloodstream infections in hemodialysis patients. RESULTS: The estimated annual number of patients receiving chronic hemodialysis increased steadily over the study period (p < 0.001), whereas the number of blood isolates increased initially, then decreased significantly, from 180 in 2011 to 93 in 2014 (p = 0.04). Gram-positive bacteria represented 72.6% (743/1024) of isolates, including Staphylococcus aureus (36.9%, 378/1024) and coagulase-negative staphylococci (23.1%, 237/1024). Only 26.1% (267/1024) of the isolates were gram-negative bacteria, the majority Enterobacteriaceae. The overall rate of methicillin resistance in S. aureus was 17.5%, and although annual rates were variable, there was a significant increase over time (p = 0.04). Antibiotic resistance in gram-negative bacteria was relatively low, except in Escherichia coli, where 13.5% and 16.2% of isolates were resistant to ceftriaxone and ciprofloxacin, respectively. Empiric therapy with vancomycin plus an agent for gram-negative coverage was predicted to cover 98.8% to 99.7% of blood isolates from hemodialysis patients, whereas cefazolin plus an agent for gram-negative coverage would cover only 67.5% to 68.4%. CONCLUSIONS: In an era of increasing antimicrobial resistance, data such as these and ongoing surveillance are essential components of antimicrobial stewardship in the hemodialysis population.

CONTEXTE: Étant donné la morbidité et la mortalité associées aux infections du sang parmi les patients en hémodialyse, la compréhension de la microbiologie est essentielle à l'optimisation du traitement de cette population exposée à un risque élevé. OBJECTIFS: Mener une étude de surveillance rétrospective des isolats de sang cliniques des patients adultes en hémodialyse et prédire la couverture microbiologique des thérapies empiriques contre les infections du sang dans cette population. MÉTHODES: Les données relatives aux isolats de sang cliniques ont été recueillies dans les quatre unités ambulatoires principales d'hémodialyse à Winnipeg (Manitoba), entre 2007 et 2014. La caractérisation a porté sur la distribution des organismes et les susceptibilités aux antimicrobiens. L'évolution dans le temps a été testée au besoin à l'aide d'une analyse chronologique. Les données de l'étude ont permis de prédire et de comparer la couverture microbiologique de diverses thérapies empiriques contre les infections du sang pour les patients en hémodialyse. RÉSULTATS: On estime que le nombre annuel de patients recevant une hémodialyse chronique a augmenté régulièrement au cours de la période de l'étude (p < 0,001); le nombre d'isolats de sang a tout d'abord augmenté, puis il a grandement diminué: de 180 en 2011, il est passé à 93 en 2014 (p = 0,04). Les bactéries à Gram positif représentaient 72,6 % (743/1024) des isolats, y compris les Staphylococcus aureus (36,9 %, 378/1024) et les staphylocoques à coagulase négative (23,1 %, 237/1024). Seulement 26,1 % (267/1024) des isolats étaient des bactéries à Gram négatif, la majorité desquelles étant des Enterobacteriaceae. Le taux général de résistance à la méticilline de S. aureus était de 17,5 %, et bien que les taux annuels étaient variables, une augmentation importante a été observée avec le temps (p = 0,04). La résistance aux antibiotiques des bactéries à Gram négatif était relativement faible, sauf Escherichia coli, où respectivement 13,5 % et 16,2 % des isolats étaient résistants à la ceftriaxone et à la ciprofloxacine. On prévoyait que la thérapie empirique à la vancomycine associée à un agent pour la couverture à Gram positif couvrirait de 98,8 % à 99,7 % des isolats de sang des patients en hémodialyse, tandis que la céfazoline associée à un agent de la couverture à Gram négatif ne couvrirait que 67,5 % à 68,4 %. CONCLUSIONS: À une époque qui se caractérise par une augmentation de la résistance aux antimicrobiens, des données comme celles-ci et celles portant sur la surveillance continue sont des composantes essentielles de la bonne gestion de l'utilisation des antimicrobiens pour les patients adultes en hémodialyse.

Efficacy and Safety of Tranexamic Acid in Major Non-Cardiac Surgeries at High Risk for Transfusion: A Systematic Review and Meta-Analysis.

Tranexamic acid (TXA) reduces transfusion requirements in cardiac surgery and total hip and knee arthroplasty, where it has become standard of care. Our objective is to determine the efficacy and safety of TXA in other surgeries associated with a high risk for red blood cell (RBC) transfusion. We identified randomized controlled trials in Medline, Embase, CENTRAL, and CAB abstracts from inception to June 2019. We included trials evaluating intraoperative IV TXA in adult patients undergoing a non-cardiac and non-hip and knee arthroplasty surgeries at high-risk for RBC transfusion, defined as a baseline transfusion rate ≥5% in comparator arm. We assessed risk of bias using the Cochrane Risk of Bias tool. We used GRADE methodology to assess certainty of evidence. From 8565 citations identified, we included 69 unique trials, enrolling 6157 patients. TXA reduces both the proportion of patients transfused RBCs (relative risk (RR) 0.59; 95% confidence interval (CI) 0.48 to 0.72; low certainty evidence) and the volume of RBC transfused (MD -0.51 RBC units; 95%CI -0.13 to -0.9 units; low certainty evidence) when compared to placebo or usual care. TXA was not associated with differences in deep vein thrombosis, pulmonary embolism, all-cause mortality, hospital length of stay, need for re-operation due to hemorrhage, myocardial infarction, stroke or seizure. In patients undergoing a broad range of non-cardiac and non-hip and knee arthroplasty surgeries at high risk for RBC transfusion, perioperative TXA reduced exposure to RBC transfusion. No differences in thrombotic outcomes were identified; however, summary effect estimates were limited by lack of systemic screening and short duration of follow-up.

Antimicrobial Prophylaxis for Patients Undergoing Cardiac Surgery: Intraoperative Cefazolin Concentrations and Sternal Wound Infections.

This study characterizes the pharmacodynamics of antimicrobial prophylaxis and sternal wound infections following cardiac surgery. Duration of surgery and cefazolin plasma concentration during wound closure were independently associated with surgical site infection at 30 days. Furthermore, a duration of surgery of >346 min and a total cefazolin closure concentration of <104 mg/liter were significant thresholds for an increased risk of infection. This study provides new data that informs dosing strategies for effective antimicrobial prophylaxis (AP) in patients undergoing cardiac surgery with cardiopulmonary bypass.

The Pharmacokinetics and Pharmacodynamics of Carfentanil After Recreational Exposure: A Case Report.

Carfentanil and related fentanyl analogs have been linked to a number of overdose deaths from drug users in several cities across North America. Diagnosis of carfentanil exposure requires a very high index of clinical suspicion, especially because available laboratory narcotic screens do not detect this agent. We describe a 34-year-old man admitted with depressed level of consciousness and in respiratory failure after recreational exposure to a white powder later inferred to contain carfentanil. Urine and whole blood samples were obtained for conventional preliminary drug screen immunoassays for unknown exposures, in addition to utilizing a high-pressure liquid chromatography-tandem mass spectrometry assay for quantification of carfentanil and its metabolite. The patient was intubated and required mechanically assisted ventilation for 31 hours until he was able to breathe safely on his own. Pharmacokinetic modeling of three timed blood samples identified the elimination half-life as 5.7 hours for carfentanil and 11.8 hours for the norcarfentanil metabolite. Awakening and breathing spontaneously corresponded to an interpolated blood carfentanil concentration of 0.52 ng/ml. This is the first pharmacokinetic and pharmacodynamic case report on the recreational use of carfentanil. Critical care clinicians should anticipate long periods of ventilatory support in the care of patients exposed to carfentanil.

Limitations of ceftriaxone compared with cefazolin against MSSA: an integrated pharmacodynamic analysis.

Objectives: Despite the convenience of once-daily dosing, the use of ceftriaxone for Staphylococcus aureus infections has significant limitations, including scarce clinical evidence and increasingly questionable pharmacodynamic activity. Our goal was to conduct an integrated pharmacokinetic-pharmacodynamic analysis of the appropriateness of ceftriaxone compared with cefazolin for treating serious MSSA infections. Methods: Ceftriaxone and cefazolin activity against five clinical MSSA isolates was characterized in an in vitro pharmacodynamic model. Monte Carlo simulations were then used to evaluate various dosing regimens of ceftriaxone and cefazolin based on relevant patient pharmacokinetic data, significant pharmacodynamic targets derived from the in vitro studies (55%ƒT>MIC for bacteriostasis, 75%ƒT>MIC for 1 log10 bacterial kill, 100%ƒT>MIC for ≥3 log10 bacterial kill) and MIC distributions for MSSA from national surveillance data. Results: Ceftriaxone at 1 g once daily had poor activity against MSSA with net bacterial growth predicted in 76% of simulated subjects. The standard 2 g of ceftriaxone once daily had predicted bacterial growth or bacteriostasis in 54% of cases with bactericidal effects in only 17%. Cefazolin at 2 g once daily was notably similar to ceftriaxone in expected target attainments. Cefazolin at 2 g twice daily demonstrated maximal pharmacodynamic activity with bactericidal effects in 97% of simulated subjects. Conclusions: Given the limited activity of ceftriaxone against S. aureus, particularly for serious infections when bacterial kill is desired, the convenience of once-daily dosing should be weighed against the risks of using an overly broad, suboptimal therapy. Cefazolin warrants further consideration, particularly as optimal pharmacodynamics against MSSA may be achieved with twice-daily dosing in most patients.

Evaluation of cefazolin antimicrobial prophylaxis during cardiac surgery with cardiopulmonary bypass.

Objectives: Although clinical practice guidelines recommend standard cefazolin antimicrobial prophylaxis (AP) dosing for cardiac surgery, limited data exist as to whether adequate concentrations are achieved in this patient population. The goal of our study was to characterize intraoperative cefazolin concentrations particularly at wound closure with regards to maintaining target cefazolin closure concentrations ≥40 mg/L. Methods: Adults undergoing cardiac surgery with cardiopulmonary bypass (CPB) and receiving cefazolin AP according to protocol were studied. Blood samples were collected after the preoperative cefazolin dose, prior to intraoperative cefazolin doses and at wound closure. Intraoperative trough and closure concentrations were characterized and evaluated against a target threshold of ≥ 40 mg/L (≥8 mg/L unbound, assuming 80% protein binding). Results: Fifty-five subjects (64.9 ±âŸ10.4 years, 89.7 ±âŸ16.5 kg, CLCR >50 mL/min/72 kg) completed the study. Total cefazolin concentrations were <40 mg/L in 40% (12 of 30) of intraoperative trough samples and 9.8% (5 of 51) of closure samples. Below-target concentrations at some time during surgery were documented in 30.9% (17 of 55) of subjects. In multivariate analyses, lower body weight (P = 0.027) and shorter duration of surgery (P = 0.045) were significant predictors of closure concentrations <40 mg/L. A total cefazolin exposure (preoperative and intraoperative doses) of ≥ 7.6 mg/kgdosing weight for every hour of surgery (intermittent dosing) was required to achieve target closure concentrations. Conclusions: The standard cefazolin AP regimen was not reliable in maintaining target closure concentrations ≥40 mg/L in patients with normal renal function undergoing elective cardiac surgery with CPB. The findings supported a cefazolin AP regimen consisting of at least 2 g preoperatively and every 3 h during surgery.

No role for patient body weight on renal function assessment for drug dosing.

Objectives: To evaluate the ability of body-weight-driven renal function assessment (RFA) formulae to predict on-target elimination rate ranges for gentamicin in patients with varying degrees of renal function. Methods: A 6 year retrospective pharmacokinetic study was conducted at a university teaching hospital. Results: A total of 85 patients met the inclusion criteria and 127 pharmacokinetic files were analysed from patients on medical-surgical wards (53%) and medical-surgical ICUs (13%) receiving intravenous gentamicin for treatment, as well as those for patients receiving it for surgical prophylaxis (34%). Each RFA formula was examined against standard dosing tables for gentamicin. A table of acceptable elimination rates was generated using a traditional peak of 8 mg/L and trough between 0.5 and 2 mg/L associated with each of the dosing interval extensions. The ability of each RFA formula to select on-target elimination rates was evaluated. The RFA formula assuming a normalized body weight of 72 kg and a modified creatinine reagent adjustment factor of 90% provided the most accurate on-target elimination rate selection. This method was superior to dosing interval selection based on the Modification in Diet Renal Disease (MDRD) formula, Sanford's guide method, as well as the Cockcroft-Gault formulae using total body weight, ideal body weight or lean body weight ( P < 0.0001). Conclusions: Based on the use of gentamicin as a surrogate guide for renally adjusted drugs, these results support dosing interval selection based on a normalized body weight method and a formula reagent adjustment factor of 90% within the Cockcroft-Gault formula.

Microbiological Trends and Antimicrobial Resistance in Peritoneal Dialysis-Related Peritonitis, 2005 to 2014.

♦ BACKGROUND: Information related to the microbiology of peritonitis is critical to the optimal management of patients receiving peritoneal dialysis (PD). The goal was to characterize the microbiological etiology and antimicrobial susceptibilities of PD-related peritonitis (PDRP) from 2005 to 2014, inclusive. ♦ METHODS: The distribution of organisms in culture-positive PDRP was described for new episodes and relapse infections, and further detailed for monomicrobial and polymicrobial peritonitis. Annual and overall rates of PDRP were also characterized. Antimicrobial susceptibility rates were calculated for the most common and significant organisms. ♦ RESULTS: We identified 539 episodes of PDRP including 501 new and 38 relapse infections. New episodes of peritonitis were associated with a single organism in 85% of cases, and 44% of those involved staphylococci. Polymicrobial PDRP was more likely to involve gram-negative organisms, observed in 58% versus 24% of monomicrobial infections. Antimicrobial resistance was relatively stable from 2005 to 2014. Methicillin resistance was present in 57% of Staphylococcus epidermidis and 20% of other coagulase-negative staphylococci. Methicillin-resistant Staphylococcus aureus (MRSA) accounted for only 11% of S. aureus peritonitis compared with 2% in our previous study of PDRP from 1991 to 1998. Ciprofloxacin resistance in Escherichia coli increased from 3% in our previous study to 24% in 2005 - 2014. ♦ CONCLUSIONS: This study characterizes important differences in the distribution of organisms in new episodes of PDRP and relapse infections, as well as monomicrobial versus polymicrobial peritonitis. It also shows relatively stable rates of antimicrobial resistance from 2005 to 2014, but some increases compared with our previous study.

Multifaceted antibiotic treatment analysis of methicillin-sensitive Staphylococcus aureus bloodstream infections.

Given the overall prevalence and poor prognosis of Staphylococcus aureus bloodstream infections (BSIs), the study of treatment strategies to improve patient outcomes is important. The aim of this study was to conduct a multifaceted antibiotic treatment analysis of methicillin-sensitive S. aureus (MSSA) BSI and to characterise optimal early antibiotic therapy (within the first 7 days of drawing the index blood culture) for this serious infection. Antibiotic selection was categorised as optimal targeted (intravenous cloxacillin or cefazolin), optimal broad (piperacillin/tazobactam or meropenem), adequate (vancomycin) or inadequate (other antibiotics or oral therapy). A TSE (timing, selection, exposure) score was developed to comprehensively characterise early antibiotic therapy, where higher points corresponded to prompt initiation, optimal antibiotic selection and longer exposure (duration). Amongst 71 cases of complicated MSSA-BSI, end-of-treatment (EOT) response (i.e. clinical cure) was improved when at least adequate antibiotic therapy was initiated within 24 h [71.7% (33/46) vs. 48.0% (12/25); P = 0.047]. Clinical cure was also more likely when therapy included ≥4 days of optimal targeted antibiotics within the first 7 days [74.4% (29/39) vs. 50.0% (16/32); P = 0.03]. The TSE score was an informative index of early antibiotic therapy, with EOT cure documented in 72.0% (36/50) compared with 42.9% (9/21) of cases with scores above and below 15.2, respectively (P = 0.02). In multivariable analysis, lower Charlson comorbidity index, presence of BSI on admission, and optimising early antibiotic therapy, as described above, were associated with clinical cure in patients with MSSA-BSI.

Comparison of Fentanyl and Morphine in the Prehospital Treatment of Ischemic Type Chest Pain.

In the treatment of acute coronary syndromes, reduction of sympathetic stress and catecholamine release is an important therapeutic goal. One method used to achieve this goal is pain reduction through the systemic administration of analgesia. Historically, morphine has been the analgesic of choice in ischemic cardiac pain. This randomized double-blind controlled trial seeks to prove the utility of fentanyl as an alternate first-line analgesic for ischemic-type chest pain in the prehospital setting. Successive patients who were treated for suspected ischemic chest pain in the emergency medical services system were considered eligible. Once chest pain was confirmed, patients received oxygen, aspirin, and nitroglycerin therapy. If the ischemic-type chest pain continued the patient was randomized in a double-blinded fashion to treatment with either morphine or fentanyl. Pain scale scores, necessity for additional dosing, and rate of adverse events between the groups were assessed every 5 minutes and were compared using t-testing, Fisher's Exact test, or Analysis of Variance (ANOVA) where appropriate. The primary outcome of the study was incidence of hypotension and the secondary outcome was pain reduction as measured by the visual analog score and numeric rating score. A total of 207 patients were randomized with 187 patients included in the final analysis. Of the 187 patients, 99 were in the morphine group and 88 in the fentanyl group. No statistically significant difference between the two groups with respect to hypotension was found (morphine 5.1% vs. fentanyl 0%, p = 0.06). Baseline characteristics, necessity for additional dosing, and other adverse events between the two groups were not statistically different. There were no significant differences between the changes in visual analog scores and numeric rating scale scores for pain between the two groups (p = 0.16 and p = 0.15, respectively). This study supports that fentanyl and morphine are comparable in providing analgesia for ischemic-type chest pain. Fentanyl appears to be a safe and effective alternative to morphine for the management of chest pain in the prehospital setting.

Post-operative nausea and vomiting in the cardiac surgery population: who is at risk?

OBJECTIVES: Post-operative nausea and vomiting (PONV) is a common and distressing complication following cardiac surgery. Therefore, our primary objective was to explore the predictors of severe PONV in the cardiac surgery population. METHODS: A retrospective study was completed on cardiac surgery patients (N = 150). A modified preoperative PONV risk assessment tool was utilized to identify patients at high and low risk for PONV. RESULTS: 54% of the high-risk group versus 13% of the low-risk group experienced ≥2 nausea events in the early post-operative period (p < 0.0001). The high-risk group had a uniquely elevated and sustained number of PONV events post-operatively. History of PONV (p = 0.03) and female gender (p = 0.01) emerged as significant predictors of any nausea event. CONCLUSIONS: A specific PONV risk assessment tool may be useful for predicting those at highest risk following cardiac surgery. Further research is required to identify strategies to reduce PONV.

Preoperative therapeutic apheresis for severe medically refractory amiodarone-induced thyrotoxicosis: a case report.

INTRODUCTION: Amiodarone is associated with thyroid dysfunction and life-threatening thyrotoxicosis. In medically refractory cases, or where medical therapy is contraindicated, thyroidectomy may be required. To decrease perioperative thyroid storm and to reduce overall surgical risk, apheresis may be considered preoperatively to restore euthyroidism. CASE DESCRIPTION: We report a 46-year-old female with a history of cardiac arrhythmia and tachycardia-induced cardiomyopathy for which she received amiodarone. Months after discontinuation of amiodarone, the patient presented with wide complex tachycardia and symptoms of thyrotoxicosis. Laboratory testing confirmed severe thyrotoxicosis which was subsequently refractory to medical therapy. Total thyroidectomy was required. Following a total of 10 apheresis treatments, thyroid hormone levels were reduced to near normal levels and the patient's symptoms improved. Thyroidectomy was performed without intraoperative or postoperative complication. DISCUSSION: In the setting of life-threatening, medically refractory amiodarone-induced thyrotoxicosis, therapeutic apheresis can effectively reduce thyroid hormone levels and restore a state of clinical and biochemical euthyroidism.