Effect of different renal function on antibacterial effects of piperacillin against Pseudomonas aeruginosa evaluated via the hollow-fibre infection model and mechanism-based modelling

BACKGROUND

Pathophysiological changes in critically ill patients can cause severely altered pharmacokinetics and widely varying antibiotic exposures. The impact of altered pharmacokinetics on bacterial killing and resistance has not been characterized in the dynamic hollow-fibre in vitro infection model (HFIM).

METHODS

A clinical Pseudomonas aeruginosa isolate (piperacillin MIC 4 mg/L) was studied in the HFIM (inoculum ∼10(7) cfu/mL). Pharmacokinetic profiles of three piperacillin dosing regimens (4 g 8-, 6- and 4-hourly, 30 min intravenous infusion) as observed in critically ill patients with augmented renal clearance (ARC), normal renal function or impaired renal function (creatinine clearances of 250, 110 or 30 mL/min, respectively) were simulated over 7 days. The time courses of total and less-susceptible populations and MICs were determined. Mechanism-based modelling was performed in S-ADAPT.

RESULTS

For all regimens with ARC and regimens with 8- or 6-hourly dosing with normal renal function, initial killing of ≤∼2 log10 was followed by regrowth to 10(8)-10(9) cfu/mL at 48 h. For 8- and 6-hourly dosing at normal renal function, the proportion of less-susceptible colonies increased ∼10-100-fold above those in ARC and control arms. Regimens achieving an fCmin of ≥5× MIC resulted in bacterial killing of 3-4 log10 without regrowth and suppressed less-susceptible populations to ≤∼2 log10. The mechanism-based model successfully quantified the time course of bacterial growth, killing and regrowth.

CONCLUSIONS

Only high piperacillin concentrations prevented regrowth of P. aeruginosa. Individualized dosing regimens that account for altered pharmacokinetics and aim for higher-than-standard antibiotic exposures to achieve an fCmin of ≥5× MIC were required to maximize bacterial killing and suppress emergence of resistance.

Pulse Pressure Variation Adjusted by Respiratory Changes in Pleural Pressure, Rather Than by Tidal Volume, Reliably Predicts Fluid Responsiveness in Patients With Acute Respiratory Distress Syndrome

OBJECTIVES

1) To evaluate the ability of pulse pressure variation adjusted by respiratory changes in pleural pressure to predict fluid responsiveness compared with pulse pressure variation alone. 2) To identify factors explaining the poor performance of pulse pressure variation in acute respiratory distress syndrome.

DESIGN

Prospective study.

SETTING

Forty-bed university hospital general ICU.

PATIENTS

Ninety-six mechanically ventilated acute respiratory distress syndrome patients requiring fluid challenge.

INTERVENTIONS

Fluid challenge, 500 mL saline over 20 minutes.

MEASUREMENTS AND MAIN RESULTS

Before fluid challenge, esophageal pressure was measured at the end-inspiratory and end-expiratory occlusions. Change in pleural pressure was calculated as the difference between esophageal pressure measured at end-inspiratory and end-expiratory occlusions. Hemodynamic measurements were obtained before and after the fluid challenge. Patients were ventilated with tidal volume 7.0 ± 0.8 mL/kg predicted body weight. The fluids increased cardiac output by greater than 15% in 52 patients (responders). Adjusting pulse pressure variation for changes in pleural pressure (area under the receiver operating characteristic curve, 0.94 [0.88-0.98]) and the ratio of chest wall elastance to total respiratory system elastance (area under the receiver operating characteristic curve, 0.93 [0.88-0.98]) predicted fluid responsiveness better than pulse pressure variation (area under the receiver operating characteristic curve, 0.78 [0.69-0.86]; all p < 0.01). The gray zone approach identified a range of pulse pressure variation/changes in pleural pressure values (1.94-2.1) in 3.1% of patients for whom fluid responsiveness could not be predicted reliably. On logistic regression analysis, two independent factors affected the correct classification of fluid responsiveness at a 12% pulse pressure variation cutoff: tidal volume (adjusted odds ratio 1.57/50 mL; 95% CI, 1.05-2.34; p = 0.027) and chest wall elastance/respiratory system elastance (adjusted odds ratio, 2.035/0.1 unit; 95% CI, 1.36-3.06; p = 0.001). In patients with chest wall elastance/respiratory system elastance above the median (0.28), pulse pressure variation area under the receiver operating characteristic curve was 0.94 (95% CI, 0.84-0.99) compared with 0.76 (95% CI, 0.61-0.87) otherwise (p = 0.02).

CONCLUSIONS

In acute respiratory distress syndrome patients, pulse pressure variation adjusted by changes in pleural pressure is a reliable fluid responsiveness predictor despite the low tidal volume (< 8 mL/kg). The poor predictive ability of pulse pressure variation in acute respiratory distress syndrome patients is more related to low chest wall elastance/respiratory system elastance ratios than to a low tidal volume.

Predicting and measuring fluid responsiveness with echocardiography

Echocardiography is ideally suited to guide fluid resuscitation in critically ill patients. It can be used to assess fluid responsiveness by looking at the left ventricle, aortic outflow, inferior vena cava and right ventricle. Static measurements and dynamic variables based on heart–lung interactions all combine to predict and measure fluid responsiveness and assess response to intravenous fluid resuscitation. Thorough knowledge of these variables, the physiology behind them and the pitfalls in their use allows the echocardiographer to confidently assess these patients and in combination with clinical judgement manage them appropriately.

Multidrug-resistant bacteria in hematology patients: emerging threats

Multidrug-resistant (MDR) bacteria, particularly Gram negatives, such as Enterobacteriaceae resistant to third-generation cephalosporins or carbapenems and MDR Pseudomonas aeruginosa, are increasingly frequent in hematology patients. The prevalence of different resistant species varies significantly between centers. Thus, the knowledge of local epidemiology is mandatory for deciding the most appr-opriate management protocols. In the era of increasing antibiotic resistance, empirical therapy of febrile neutropenia should be individualized. A de-escalation approach is recommended in case of severe clinical presentation in patients who are at high risk for infection with a resistant strain. Targeted therapy of an MDR Gram negative usually calls for a combination treatment, although no large randomized trials exist in this setting. Infection control measures are the cornerstone of limiting the spread of MDR pathogens in hematology units.

Advances in antibiotic therapy in the critically ill

Infections occur frequently in critically ill patients and their management can be challenging for various reasons, including delayed diagnosis, difficulties identifying causative microorganisms, and the high prevalence of antibiotic-resistant strains. In this review, we briefly discuss the importance of early infection diagnosis, before considering in more detail some of the key issues related to antibiotic management in these patients, including controversies surrounding use of combination or monotherapy, duration of therapy, and de-escalation. Antibiotic pharmacodynamics and pharmacokinetics, notably volumes of distribution and clearance, can be altered by critical illness and can influence dosing regimens. Dosing decisions in different subgroups of patients, e.g., the obese, are also covered. We also briefly consider ventilator-associated pneumonia and the role of inhaled antibiotics. Finally, we mention antibiotics that are currently being developed and show promise for the future.

The ANTIBIOPERF study: a nationwide cross-sectional survey about practices for β-lactam administration and therapeutic drug monitoring among critically ill patients in France

Our objective was to assess current practices about the administration (intermittent, extended, or continuous infusions) and therapeutic drug monitoring (TDM) of β-lactam antibiotics and vancomycin in France. We conducted a nationwide cross-sectional survey in May-August 2015, using an online questionnaire, sent as an e-mail link to infectious disease specialists and intensive care specialists through national mailing lists. We used clinical vignettes of critically ill patients to assess physicians' practices about administration and TDM practices for amoxicillin, cloxacillin, piperacillin/tazobactam, cefotaxime, ceftazidime, cefepime, meropenem and vancomycin. In all, 507 physicians participated (507/1200, response rate 42%). TDM was rarely available for β-lactams (from 16.5% (81/490) for cloxacillin to 30% (145/490) for ceftazidime), whereas vancomycin TDM was available in 97% (477/490) of the cases. In the clinical vignettes, ceftazidime and piperacillin/tazobactam were the β-lactams administered most frequently by extended or continuous infusions (76% (336/440) and 57% (252/444), respectively). Gaps in knowledge about the duration of stability of intravenous β-lactams were common (correct answers ranged from 8% (35/432) for cloxacillin to 33% (146/438) for ceftazidime). Most physicians (77%, 339/442) were convinced of the value of extended or continuous infusions for β-lactams in critically ill patients, but 48% (211/442) did not have access to practical guidelines. Our survey found that most infectious disease and intensive care specialists are favourable to optimized administration of β-lactams in critically ill patients. But the lack of guidelines and limited TDM availability for β-lactams in hospitals are potential barriers to its implementation.

Critical Care Ultrasound: A Review for Practicing Nephrologists

The use of point-of-care ultrasound in the intensive care unit, both for diagnostic and procedural purposes, has rapidly proliferated, and evidence supporting its use is growing. Conceptually, critical care ultrasound (CCUS) should be considered an extension of the physical examination and should not be considered a replacement for formal echocardiography or radiology-performed ultrasound. Several CCUS applications are of particular relevance to nephrologists, including focused renal ultrasound in patients at high risk for urinary tract obstruction, real-time ultrasound guidance and verification during the placement of central venous catheters, and ultrasound-augmented assessment of shock and volume status. Each of these applications has the capacity to improve outcomes in patients with acute kidney injury. Although robust evidence regarding long-term outcomes is lacking, existing data demonstrate that CCUS has the potential to improve diagnostic accuracy, expedite appropriate management, and increase safety for critically ill patients across a spectrum of pathologies.

Should β-lactam antibiotics be administered by continuous infusion in critically ill patients? A survey of Australia and New Zealand intensive care unit doctors and pharmacists

Although there is a biological precedent for administration of β-lactam antibiotics by continuous or extended infusion, there is no definitive evidence of a survival benefit compared with intermittent administration. The aim of this study was to explore clinician uncertainty with regard to the administration of β-lactam antibiotics by continuous infusion. Doctors and pharmacists in Australian and New Zealand intensive care units (ICUs) were surveyed to investigate current β-lactam antibiotic administration practices as well as the degree of uncertainty regarding the benefit of continuous infusion of two commonly used broad-spectrum β-lactams, namely meropenem and piperacillin/tazobactam (TZP). There were 111 respondents to the survey. Intermittent infusion was reported as standard practice for meropenem (73.9%) and TZP (82.0%). A greater proportion of pharmacists compared with doctors believed continuous infusion to be more effective than intermittent administration (85.4% vs. 34.3%, respectively; P <0.001). Both groups reported uncertainty as to whether administration by continuous infusion resulted in better patient outcomes (65.9% and 74.6%, respectively; P = 0.85). Overall, 91.0% of respondents were prepared to enrol eligible patients into a definitive randomised controlled trial on β-lactam antibiotic administration. In conclusion, there is equipoise among clinicians working in Australian and New Zealand ICUs as to whether administration by continuous infusion offers a survival benefit in critically ill patients.

Prognostic impact of left ventricular diastolic function in patients with septic shock

Background

Left ventricular (LV) diastolic dysfunction is highly prevalent in the general population and associated with a significant morbidity and mortality. Its prognostic role in patients sustaining septic shock in the intensive care unit (ICU) remains controversial. Accordingly, we investigated whether LV diastolic function was independently associated with ICU mortality in a cohort of septic shock patients assessed using critical care echocardiography.

Methods

Over a 5-year period, patients hospitalized in a Medical–Surgical ICU who underwent an echocardiographic assessment with digitally stored images during the initial management of a septic shock were included in this retrospective single-center study. Off-line echocardiographic measurements were independently performed by an expert in critical care echocardiography who was unaware of patients’ outcome. LV diastolic dysfunction was defined by the presence of a lateral E′ maximal velocity <10 cm/s. A multivariate analysis was performed to determine independent risk factors associated with ICU mortality.

Results

Among the 540 patients hospitalized in the ICU with septic shock during the study period, 223 were studied (140 men [63 %]; age 64 ± 13 years; SAPS II 55 ± 18; SOFA 10 ± 3; Charlson 3.5 ± 2.5) and 204 of them (91 %) were mechanically ventilated. ICU mortality was 35 %. LV diastolic dysfunction was observed in 31 % of patients. The proportion of LV diastolic dysfunction tended to be higher in non-survivors than in their counterparts (28/78 [36 %] vs. 41/145 [28 %]: p = 0.15). Inappropriate initial antibiotic therapy (OR 4.17 [CI 95 % 1.33–12.5]: p = 0.03), maximal dose of vasopressors (OR 1.38 [CI 95 % 1.16–1.63]: p = 0.01), SOFA score (OR 1.16 [CI 95 % 1.02–1.32]: p = 0.02) and lateral E′ maximal velocity (OR 1.12 [CI 95 % 1.01–1.24]: p = 0.02) were independently associated with ICU mortality. After adjusting for the SAPS II score, inappropriate initial antibiotic therapy and maximal dose of vasopressors remained independent factors for ICU mortality, whereas a trend was only observed for lateral E′ maximal velocity (OR 1.11 [CI 95 % 0.99–1.23]: p = 0.07).

Conclusion

The present study suggests that LV diastolic function might be associated with ICU mortality in patients with septic shock. A multicenter prospective study assessing a large cohort of patients using serial echocardiographic examinations remains required to confirm the prognostic value of LV diastolic dysfunction in septic shock.

Point of Care Ultrasound Accurately Distinguishes Inflammatory from Noninflammatory Disease in Patients Presenting with Abdominal Pain and Diarrhea

Background. Approaches to distinguish inflammatory bowel disease (IBD) from noninflammatory disease that are noninvasive, accurate, and readily available are desirable. Such approaches may decrease time to diagnosis and better utilize limited endoscopic resources. The aim of this study was to evaluate the diagnostic accuracy for gastroenterologist performed point of care ultrasound (POCUS) in the detection of luminal inflammation relative to gold standard ileocolonoscopy. Methods. A prospective, single-center study was conducted on convenience sample of patients presenting with symptoms of diarrhea and/or abdominal pain. Patients were offered POCUS prior to having ileocolonoscopy. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) with 95% confidence intervals (CI), as well as likelihood ratios, were calculated. Results. Fifty-eight patients were included in this study. The overall sensitivity, specificity, PPV, and NPV were 80%, 97.8%, 88.9%, and 95.7%, respectively, with positive and negative likelihood ratios (LR) of 36.8 and 0.20. Conclusion. POCUS can accurately be performed at the bedside to detect transmural inflammation of the intestine. This noninvasive approach may serve to expedite diagnosis, improve allocation of endoscopic resources, and facilitate initiation of appropriate medical therapy.

Transpulmonary thermodilution (TPTD) before, during and after Sustained Low Efficiency Dialysis (SLED). A Prospective Study on Feasibility of TPTD and Prediction of Successful Fluid Removal

BACKGROUND

Acute kidney injury (AKI) is common in critically ill patients. AKI requires renal replacement therapy (RRT) in up to 10% of patients. Particularly during connection and fluid removal, RRT frequently impairs haemodyamics which impedes recovery from AKI. Therefore, "acute" connection with prefilled tubing and prolonged periods of RRT including sustained low efficiency dialysis (SLED) has been suggested. Furthermore, advanced haemodynamic monitoring using trans-pulmonary thermodilution (TPTD) and pulse contour analysis (PCA) might help to define appropriate fluid removal goals.

OBJECTIVES, METHODS

Since data on TPTD to guide RRT are scarce, we investigated the capabilities of TPTD- and PCA-derived parameters to predict feasibility of fluid removal in 51 SLED-sessions (Genius; Fresenius, Germany; blood-flow 150 mL/min) in 32 patients with PiCCO-monitoring (Pulsion Medical Systems, Germany). Furthermore, we sought to validate the reliability of TPTD during RRT and investigated the impact of "acute" connection and of disconnection with re-transfusion on haemodynamics. TPTDs were performed immediately before and after connection as well as disconnection.

RESULTS

Comparison of cardiac index derived from TPTD (CItd) and PCA (CIpc) before, during and after RRT did not give hints for confounding of TPTD by ongoing RRT. Connection to RRT did not result in relevant changes in haemodynamic parameters including CItd. However, disconnection with re-transfusion of the tubing volume resulted in significant increases in CItd, CIpc, CVP, global end-diastolic volume index GEDVI and cardiac power index CPI. Feasibility of the pre-defined ultrafiltration goal without increasing catecholamines by >10% (primary endpoint) was significantly predicted by baseline CPI (ROC-AUC 0.712; p = 0.010) and CItd (ROC-AUC 0.662; p = 0.049).

CONCLUSIONS

TPTD is feasible during SLED. "Acute" connection does not substantially impair haemodynamics. Disconnection with re-transfusion increases preload, CI and CPI. The extent of these changes might be used as a "post-RRT volume change" to guide fluid removal during subsequent RRTs. CPI is the most useful marker to guide fluid removal by SLED.

Therapeutic drug monitoring of anti-infective agents in critically ill patients

Initial adequate anti-infective therapy is associated with significantly improved clinical outcomes for patients with severe infections. However, in critically ill patients, several pathophysiological and/or iatrogenic factors may affect the pharmacokinetics of anti-infective agents leading to suboptimal drug exposure, in particular during the early phase of therapy. Therapeutic drug monitoring (TDM) may assist to overcome this problem. We discuss the available evidence on the use of TDM in critically ill patient populations for a number of anti-infective agents, including aminoglycosides, β-lactams, glycopeptides, antifungals and antivirals. Also, we present the available evidence on the practices of anti-infective TDM and describe the potential utility of TDM to improve treatment outcome in critically ill patients with severe infections. For aminoglycosides, glycopeptides and voriconazole, beneficial effects of TDM have been established on both drug effectiveness and potential side effects. However, for other drugs, therapeutic ranges need to be further defined to optimize treatment prescription in this setting.

Assessment of changes in cardiac index with calibrated pulse contour analysis in cardiac surgery: A prospective observational study

OBJECTIVES

To assess the trending ability of calibrated pulse contour cardiac index (CIPC) monitoring during haemodynamic changes (passive leg raising [PLR] and fluid loading) compared with transpulmonary thermodilution CI (CITD).

METHOD

Seventy-eight mechanically-ventilated patients admitted to intensive care with calibrated pulse contour following cardiac surgery were prospectively included and investigated during PLR, and after fluid loading. Fluid responsiveness was defined as a≥15% CITD increase after a 500ml bolus. Areas under the empiric receiver operating characteristic curves (ROCAUC) for changes in CIPC (ΔCIPC) during PLR to predict fluid responsiveness and after fluid challenge to predict an increase at least 15% in CITD after fluid loading were calculated.

RESULTS

Fifty-five patients (71%) were classified as responders, 23 (29%) as non-responders. ROCAUC for ΔCIPC during PLR in predicting fluid responsiveness, its sensitivity, specificity, and percentage of patients within the inconclusive class of response were 0.67 (95% CI=0.55-0.77), 0.76 (95% CI=0.63-0.87), 0.57 (95% CI=0.34-0.77) and 68%, respectively. Bias, precision and limits of agreements and percentage error between CIPC and CITD after fluid challenge were 0.14 (95% CI: 0.08-0.20), 0.26, -0.37 to 0.64 l min(-1)m(-2), and 20%, respectively. The concordance rate was 97% and the polar concordance at 30° was 91%. ROCAUC for ΔCIPC in predicting an increase of at least 15% in CITD after fluid loading was 0.85 (95% CI: 0.76-0.92).

CONCLUSION

Although ΔCIPC after fluid loading could track the direction of changes of CITD and was interchangeable with bolus transpulmonary thermodilution, PLR could not predict fluid responsiveness in cardiac surgery patients.

Community-Acquired Pyelonephritis in Pregnancy Caused by KPC-Producing Klebsiella pneumoniae

Carbapenem-resistant Enterobacteriaceae (CRE) usually infect patients with significant comorbidities and health care exposures. We present a case of a pregnant woman who developed community-acquired pyelonephritis caused by KPC-producing Klebsiella pneumoniae. Despite antibiotic treatment, she experienced spontaneous prolonged rupture of membranes, with eventual delivery of a healthy infant. This report demonstrates the challenge that CRE may pose to the effective treatment of common infections in obstetric patients, with potentially harmful consequences to maternal and neonatal health.

The use and risks of antibiotics in critically ill patients

INTRODUCTION

The altered pathophysiology in critically ill patients presents a unique challenge in both the diagnosis of infection and the appropriate prescription of antibiotics. In this context, the importance of effective and timely treatment needs to be weighed against the individual and community harms associated with antibiotic collateral damage and antibiotic resistance.

AREAS COVERED

We evaluate the principles of antibiotic use in critically ill patients, including dose optimisation, use of combination antibiotic therapy, therapeutic drug monitoring, appropriate antibiotic therapy duration, de-escalation, and utilisation of sepsis biomarkers. We also describe the potential risks associated with antibiotic therapy including antibiotic resistance, delayed treatment, treatment failure, and collateral damage.

EXPERT OPINION

Prescribing teams must be aware of the impact of critical illness on their patients and tailor antibiotic therapy appropriately to prevent the significant harms associated with suboptimal antibiotic administration.

Piperacillin concentration in relation to therapeutic range in critically ill patients--a prospective observational study

BACKGROUND

Piperacillin levels after standard dosing have been shown frequently to be subtherapeutic, especially when renal clearance was augmented. Here, we aimed to determine if piperacillin was in its therapeutic range in a typically heterogeneous intensive care unit patient group, and also to describe target attainment dependent on daily dosage, creatinine clearance, and renal replacement therapy (RRT).

METHODS

Sixty patients with severe infections were included in this monocentric prospective observational study. Patients received 4.5 g of piperacillin-tazobactam two to three times daily by intermittent infusion depending on renal function according to clinical guidelines. Over 4 days, multiple serum samples (median per patient, 29; in total, 1627) were obtained to determine total piperacillin concentrations using ultra-high-performance liquid chromatography/tandem mass spectrometry.

RESULTS

A high heterogeneity of patient characteristics was observed (e.g., on day 1: creatinine clearance 2-233 mL/min and ten patients on RRT). Piperacillin trough levels showed inter-individual variation from 123 to >1785-fold on different study days. Each day, approximately 50% and 60% of the patients had piperacillin levels below the target ranges 1 and 2, respectively [defined for the calculated unbound piperacillin fraction according to the literature as 100% time above MIC (100%fT > MIC) (target range 1) and ≥ 50%fT > 4 × MIC (target range 2); MIC = 16 mg/L]. Whereas only the minority of patients who received piperacillin-tazobactam three times daily (TID) reached target 1 (38% on day 1), most patients who received piperacillin-tazobactam only twice daily (BID) because of severely impaired renal function reached this target (100% on day 1). Patients with RRT had significant higher percentages of fT > MIC. Zero percent, 55% and 100% of patients without RRT who received antibiotics TID reached target 1 when creatinine clearance was > 65 mL/min, 30-65 mL/min and < 30 mL/min, respectively. In patients with causative strains only sensitive to piperacillin-tazobactam of all antibiotics given to the patient, piperacillin levels negatively correlated with CRP concentrations of day 4 (p < 0.05).

CONCLUSIONS

A dosage of 4.5 g piperacillin-tazobactam TID seems to be frequently insufficient in critically ill patients, and also in patients where renal function is mildly to moderately impaired. For these patients, prescription of 4.5 g piperacillin-tazobactam four times daily could be considered.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01793012. Registered 24 January 2013.

A Multicenter Randomized Trial of Continuous versus Intermittent β-Lactam Infusion in Severe Sepsis

RATIONALE

Continuous infusion of β-lactam antibiotics may improve outcomes because of time-dependent antibacterial activity compared with intermittent dosing.

OBJECTIVES

To evaluate the efficacy of continuous versus intermittent infusion in patients with severe sepsis.

METHODS

We conducted a randomized controlled trial in 25 intensive care units (ICUs). Participants commenced on piperacillin-tazobactam, ticarcillin-clavulanate, or meropenem were randomized to receive the prescribed antibiotic via continuous or 30-minute intermittent infusion for the remainder of the treatment course or until ICU discharge. The primary outcome was the number of alive ICU-free days at Day 28. Secondary outcomes were 90-day survival, clinical cure 14 days post antibiotic cessation, alive organ failure-free days at Day 14, and duration of bacteremia.

MEASUREMENTS AND MAIN RESULTS

We enrolled 432 eligible participants with a median age of 64 years and an Acute Physiology and Chronic Health Evaluation II score of 20. There was no difference in ICU-free days: 18 days (interquartile range, 2-24) and 20 days (interquartile range, 3-24) in the continuous and intermittent groups (P = 0.38). There was no difference in 90-day survival: 74.3% (156 of 210) and 72.5% (158 of 218); hazard ratio, 0.91 (95% confidence interval, 0.63-1.31; P = 0.61). Clinical cure was 52.4% (111 of 212) and 49.5% (109 of 220); odds ratio, 1.12 (95% confidence interval, 0.77-1.63; P = 0.56). There was no difference in organ failure-free days (6 d; P = 0.27) and duration of bacteremia (0 d; P = 0.24).

CONCLUSIONS

In critically ill patients with severe sepsis, there was no difference in outcomes between β-lactam antibiotic administration by continuous and intermittent infusion. Australian New Zealand Clinical Trials Registry number (ACT RN12612000138886).

Bloodstream infections in the Intensive Care Unit

Bloodstream infections (BSIs) represent a common complication among critically ill patients and a leading cause of morbidity and mortality. The prompt initiation of an effective antibiotic therapy is necessary in order to reduce mortality and to improve clinical outcomes. However, the choice of the empiric antibiotic regimen is often challenging, due to the worldwide spread of multi-drug resistant (MDR) organisms with reduced susceptibility to the available broad-spectrum antimicrobials. New therapeutic strategies are 5 to improve the effectiveness of antibiotic treatment while minimizing the risk of resistance selection.

Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study

Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients.

Targeted benefits of prolonged-infusion piperacillin-tazobactam in an in vitro infection model of Pseudomonas aeruginosa

Given the inconsistent clinical findings, our goal was to characterize the pharmacodynamics (PDs) of prolonged-infusion piperacillin-tazobactam (TZP) in an in vitro pharmacodynamic model of Pseudomonas aeruginosa. Specifically, the study was designed to investigate the influence of MIC on the activity of prolonged-infusion TZP using pharmacokinetics (PKs) consistent with a non-critically ill patient population. There was no benefit with prolonged- compared with standard-infusion TZP against isolates with susceptible MICs of 8 or 16 mg/L. However, prolonged-infusion TZP produced more than two times the final bacterial kill against less susceptible isolates with an intermediate MIC of 32 mg/L. The PDs of TZP were well described by a sigmoid Emax model (r(2) = 0.84) where %ƒT>MIC thresholds of 27 and 75% were associated with bacteriostatic and bactericidal effects, respectively. However, the well-established PD relationship with %ƒT>MIC was not observed with prolonged-infusion TZP. In conclusion, this study characterizes the targeted benefits of prolong-infusion TZP based on pathogen MIC, and supports the assertion that the benefits are selective and most likely observed in patients with less susceptible pathogens or altered PKs.

Pharmacokinetics of Continuous Infusion Meropenem With Concurrent Extracorporeal Life Support and Continuous Renal Replacement Therapy: A Case Report

Pharmacokinetic parameters can be significantly altered for both extracorporeal life support (ECLS) and continuous renal replacement therapy (CRRT). This case report describes the pharmacokinetics of continuous-infusion meropenem in a patient on ECLS with concurrent CRRT. A 2.8-kg, 10-day-old, full-term neonate born via spontaneous vaginal delivery presented with hypothermia, lethargy, and a ~500-g weight loss from birth. She progressed to respiratory failure on hospital day 2 (HD 2) and developed sepsis, disseminated intravascular coagulation, and liver failure as a result of disseminated adenoviral infection. By HD 6, acute kidney injury was evident, with progressive fluid overload >1500 mL (+) for the admission. On HD 6 venoarterial ECLS was instituted for lung protection and fluid removal. On HD 7 she was initiated on CRRT. On HD 12, a blood culture returned positive and subsequently grew Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) for meropenem of 0.25 mg/L. She was started on vancomycin, meropenem, and amikacin. A meropenem bolus of 40 mg/kg was given, followed by a continuous infusion of 10 mg/kg/hr (240 mg/kg/day). On HD 15 (ECLS day 9) a meropenem serum concentration of 21 mcg/mL was obtained, corresponding to a clearance of 7.9 mL/kg/min. Repeat cultures from HDs 13 to 15 (ECLS days 7-9) were sterile. This meropenem regimen was successful in providing a target attainment of 100% for serum concentrations above the MIC for ≥40% of the dosing interval and was associated with a sterilization of blood in this complex patient on concurrent ECLS and CRRT circuits.

Therapeutic management of peritonitis: a comprehensive guide for intensivists

PURPOSE

The management of peritonitis in critically ill patients is becoming increasingly complex due to their changing characteristics and the growing prevalence of multidrug-resistant (MDR) bacteria.

METHODS

A multidisciplinary panel summarizes the latest advances in the therapeutic management of these critically ill patients.

RESULTS

Appendicitis, cholecystitis and bowel perforation represent the majority of all community-acquired infections, while most cases of healthcare-associated infections occur following suture leaks and/or bowel perforation. The micro-organisms involved include a spectrum of Gram-positive and Gram-negative bacteria, as well as anaerobes and fungi. Healthcare-associated infections are associated with an increased likelihood of MDR pathogens. The key elements for success are early and optimal source control and adequate surgery and appropriate antibiotic therapy. Drainage, debridement, abdominal cleansing, irrigation, and control of the source of contamination are the major steps to ensure source control. In life-threatening situations, a "damage control" approach is the safest way to gain time and achieve stability. The initial empirical antiinfective therapy should be prescribed rapidly and must target all of the micro-organisms likely to be involved, including MDR bacteria and fungi, on the basis of the suspected risk factors. Dosage adjustment needs to be based on pharmacokinetic parameters. Supportive care includes pain management, optimization of ventilation, haemodynamic and fluid monitoring, improvement of renal function, nutrition and anticoagulation.

CONCLUSIONS

The majority of patients with peritonitis develop complications, including worsening of pre-existing organ dysfunction, surgical complications and healthcare-associated infections. The probability of postoperative complications must be taken into account in the decision-making process prior to surgery.

Increasing Prevalence of Aminoglycoside-Resistant Enterococcus faecalis Isolates Due to the aac(6')-aph(2") Gene: A Therapeutic Problem in Kermanshah, Iran

Background:

Enterococci are important pathogens in nosocomial infections. Various types of antibiotics, such as aminoglycosides, are used for treatment of these infections. Enterococci can acquire resistant traits, which can lead to therapeutic problems with aminoglycosides.

Objectives:

This study was designed to identify the prevalence of, and to compare, the aac(6’)-aph(2”) and aph(3)-IIIa genes and their antimicrobial resistance patterns among Enterococcus faecalis and E. faecium isolates from patients at Imam Reza hospital in Kermanshah in 2011 - 2012.

Patients and Methods:

One hundred thirty-eight clinical specimens collected from different wards of Imam Reza hospital were identified to the species level by biochemical tests. Antimicrobial susceptibility tests against kanamycin, teicoplanin, streptomycin, imipenem, ciprofloxacin, and ampicillin were performed by the disk diffusion method. The minimum inhibitory concentrations of gentamicin, streptomycin, kanamycin, and amikacin were evaluated with the microbroth dilution method. The aminoglycoside resistance genes aac(6’)-aph(2”) and aph(3”)-IIIa were analyzed with multiplex PCR.

Results:

The prevalence of isolates was 33 (24.1%) for E. faecium and 63 (46%) for E. faecalis. Eighty-nine percent of the isolates were high-level gentamicin resistant (HLGR), and 32.8% of E. faecium isolates and 67.2% of E. faecalis isolates carried aac(6’)-aph(2”). The prevalence of aph(3”)-IIIa among the E. faecalis and E. faecium isolates was 22.7% and 77.3%, respectively.

Conclusions:

Remarkably increased incidence of aac(6’)-aph(2”) among HLGR isolates explains the relationship between this gene and the high level of resistance to aminoglycosides. As the resistant gene among enterococci can be transferred, the use of new-generation antibiotics is necessary.

Real-time ultrasound-guided infraclavicular axillary vein cannulation: A prospective study in mechanically ventilated critically ill patients

PURPOSE

The main purpose of this study was to define the venipuncture and catheterization success rates and early mechanical complication rates of ultrasound-guided infraclavicular axillary vein cannulation.

MATERIALS AND METHODS

We performed in-plane, real-time, ultrasound-guided infraclavicular axillary vein catheterizations under emergency and nonemergency conditions in mechanically ventilated, critically ill patients.

RESULTS

We performed 202 cannulation attempts. One hundred and twenty-six procedures (62.4%) were performed under emergency conditions. The puncture of the axillary vein was successful in 98.5% of patients, and the entire procedure success rate was 95.1% (95% confidence interval, 91.1%-97.6%). For the majority of patients (84.1%; P<.001, exact test), the venipuncture occurred during the first attempt. We noted a 22.4% overall complication rate, and most of the complications were malpositions (13.4%). We observed 8.5% of cases with potentially serious complications (puncture of the axillary artery and needle contact with the brachial plexus) and 1 case (0.5%) of pneumothorax. The puncture of the axillary artery occurred in 5 (2.5%) patients.

CONCLUSIONS

In-plane, real-time, ultrasound-guided, infraclavicular axillary vein cannulation in mechanically ventilated, critically ill patients is a safe and reliable method of central venous cannulation and can be considered to be a reasonable alternative to other central venous catheterization techniques.

Point-of-Care Echocardiography Improves Assessment of Volume Status in Cirrhosis and Hepatorenal Syndrome

The management of patients with cirrhosis along with acute kidney injury is complex and depends in large part on accurate assessment of intravascular volume status. Assessment of intravascular volume status by point-of-care echocardiography often relies solely on inferior vena cava size and variability evaluation; however, this parameter should be interpretated with an understanding of right ventricular function integrated with stroke volume and flow. Attempts to optimize intra-abdominal hemodynamics favorably are clearly problematic when physical examination findings or rudimentary assessments of central venous pressure or change in central venous pressure are used. Here, we have demonstrated the potential utility of point-of-care echocardiography to optimize the hemodynamic state in patients with decompensated cirrhosis along with acute kidney injury. This case is very unique and describes how this technique may have great promise in optimizing the intra-abdominal hemodynamics and predict the timing of large-volume paracentesis in patients with decompensated cirrhosis, which in turn can aid in promoting favorable renal recovery.

Systematic review including re-analyses of 1148 individual data sets of central venous pressure as a predictor of fluid responsiveness

PURPOSE

Central venous pressure (CVP) has been shown to have poor predictive value for fluid responsiveness in critically ill patients. We aimed to re-evaluate this in a larger sample subgrouped by baseline CVP values.

METHODS

In April 2015, we systematically searched and included all clinical studies evaluating the value of CVP in predicting fluid responsiveness. We contacted investigators for patient data sets. We subgrouped data as lower (<8 mmHg), intermediate (8-12 mmHg) and higher (>12 mmHg) baseline CVP.

RESULTS

We included 51 studies; in the majority, mean/median CVP values were in the intermediate range (8-12 mmHg) in both fluid responders and non-responders. In an analysis of patient data sets (n = 1148) from 22 studies, the area under the receiver operating curve was above 0.50 in the <8 mmHg CVP group [0.57 (95% CI 0.52-0.62)] in contrast to the 8-12 mmHg and >12 mmHg CVP groups in which the lower 95% CI crossed 0.50. We identified some positive and negative predictive value for fluid responsiveness for specific low and high values of CVP, respectively, but none of the predictive values were above 66% for any CVPs from 0 to 20 mmHg. There were less data on higher CVPs, in particular >15 mmHg, making the estimates on predictive values less precise for higher CVP.

CONCLUSIONS

Most studies evaluating fluid responsiveness reported mean/median CVP values in the intermediate range of 8-12 mmHg both in responders and non-responders. In a re-analysis of 1148 patient data sets, specific lower and higher CVP values had some positive and negative predictive value for fluid responsiveness, respectively, but predictive values were low for all specific CVP values assessed.

SaMpling Antibiotics in Renal Replacement Therapy (SMARRT): an observational pharmacokinetic study in critically ill patients

Background

Optimal antibiotic dosing is key to maximising patient survival, and minimising the emergence of bacterial resistance. Evidence-based antibiotic dosing guidelines for critically ill patients receiving RRT are currently not available, as RRT techniques and settings vary greatly between ICUs and even individual patients. We aim to develop a robust, evidence-based antibiotic dosing guideline for critically ill patients receiving various forms of RRT. We further aim to observe whether therapeutic antibiotic concentrations are associated with reduced 28-day mortality.

Methods/Design

We designed a multi-national, observational pharmacokinetic study in critically ill patients requiring RRT. The study antibiotics will be vancomycin, linezolid, piperacillin/tazobactam and meropenem. Pharmacokinetic sampling of each patient’s blood, RRT effluent and urine will take place during two separate dosing intervals. In addition, a comprehensive data set, which includes the patients’ demographic and clinical parameters, as well as modality, technique and settings of RRT, will be collected. Pharmacokinetic data will be analysed using a population pharmacokinetic approach to identify covariates associated with changes in pharmacokinetic parameters in critically ill patients with AKI who are undergoing RRT for the five commonly prescribed antibiotics.

Discussion

Using the comprehensive data set collected, the pharmacokinetic profile of the five antibiotics will be constructed, including identification of RRT and other factors indicative of the need for altered antibiotic dosing requirements. This will enable us to develop a dosing guideline for each individual antibiotic that is likely to be relevant to any critically ill patient with acute kidney injury receiving any of the included forms of RRT.

Trial registration

Australian New Zealand Clinical Trial Registry (ACTRN12613000241730) registered 28 February 2013

Classic reaction kinetics can explain complex patterns of antibiotic action

Finding optimal dosing strategies for treating bacterial infections is extremely difficult, and improving therapy requires costly and time-intensive experiments. To date, an incomplete mechanistic understanding of drug effects has limited our ability to make accurate quantitative predictions of drug-mediated bacterial killing and impeded the rational design of antibiotic treatment strategies. Three poorly understood phenomena complicate predictions of antibiotic activity: post-antibiotic growth suppression, density-dependent antibiotic effects, and persister cell formation. We show that chemical binding kinetics alone are sufficient to explain these three phenomena, using single-cell data and time-kill curves of Escherichia coli and Vibrio cholerae exposed to a variety of antibiotics in combination with a theoretical model that links chemical reaction kinetics to bacterial population biology. Our model reproduces existing observations, has a high predictive power across different experimental setups (R(2) = 0.86), and makes several testable predictions, which we verified in new experiments and by analyzing published data from a clinical trial on tuberculosis therapy. Although a variety of biological mechanisms have previously been invoked to explain post-antibiotic growth suppression, density-dependent antibiotic effects, and especially persister cell formation, our findings reveal that a simple model that considers only binding kinetics provides a parsimonious and unifying explanation for these three complex, phenotypically distinct behaviours. Current antibiotic and other chemotherapeutic regimens are often based on trial and error or expert opinion. Our "chemical reaction kinetics"-based approach may inform new strategies, which are based on rational design.

Pharmacokinetics and pharmacodynamics of piperacillin/tazobactam during high volume haemodiafiltration in patients with septic shock

BACKGROUND

The purpose of the study was to evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of piperacillin and tazobactam during high-volume haemodiafiltration (HVHDF).

METHODS

A single dose of piperacillin/tazobactam (4/0.5 g) was administered as 30 minute infusion during HVHDF to 10 patients with acute kidney injury due to septic shock. Arterial blood samples were collected before and at 30 or 60 min intervals over 8 h (12 samples) after study drug administration. Concentrations of piperacillin and tazobactam were determined by HPLC-MS/MS. R software was used for population PK analysis and Monte Carlo Simulation of probability of PK/PD target attainment (PTA) in 1000 subjects.

RESULTS

A total of 101 samples were collected during HVHDF. The median (IQR) estimated glomerular filtration rate of the patients was 16 (11.25-27.5) ml/min/1.73 m(2) and HVHDF effluent rate was 208 (146.3-298.3) ml/kg/h. A final two-compartment population PK model predicted mean (%SE) total piperacillin clearance on HVHDF was 6.9 (6.4) l/h, volume of distribution of central compartment 9.0 (10.1) l and of peripheral compartment 11.2 (12.2) l. The PTA of 50% fT>MIC for piperacillin 4 g/tazobactam 0.5 g dosed every 8 h as 0.5-h and 4-h infusion was 84.3% and 100% for MIC of 16 mg/l respectively. Aiming 100% fT>MIC of 16 mg/l, the PTA values were 88.6% and 61.0%, for piperacillin 4 g/tazobactam 0.5 g 4-h infusion every 6 and 8 h respectively.

CONCLUSIONS

For bactericidal PK/PD target attainment piperacillin/tazobactam doses of 4/0.5 g every 8 h appear appropriate in septic shock patients with minimal residual renal function during HVHDF.

Improving Patient Safety through Simulation Training in Anesthesiology: Where Are We?

There have been colossal technological advances in the use of simulation in anesthesiology in the past 2 decades. Over the years, the use of simulation has gone from low fidelity to high fidelity models that mimic human responses in a startlingly realistic manner, extremely life-like mannequin that breathes, generates E.K.G, and has pulses, heart sounds, and an airway that can be programmed for different degrees of obstruction. Simulation in anesthesiology is no longer a research fascination but an integral part of resident education and one of ACGME requirements for resident graduation. Simulation training has been objectively shown to increase the skill-set of anesthesiologists. Anesthesiology is leading the movement in patient safety. It is rational to assume a relationship between simulation training and patient safety. Nevertheless there has not been a demonstrable improvement in patient outcomes with simulation training. Larger prospective studies that evaluate the improvement in patient outcomes are needed to justify the integration of simulation training in resident education but ample number of studies in the past 5 years do show a definite benefit of using simulation in anesthesiology training. This paper gives a brief overview of the history and evolution of use of simulation in anesthesiology and highlights some of the more recent studies that have advanced simulation-based training.

Treatment of Gram-negative pneumonia in the critical care setting: is the beta-lactam antibiotic backbone broken beyond repair?

Beta-lactam antibiotics form the backbone of treatment for Gram-negative pneumonia in mechanically ventilated patients in the intensive care unit. However, this beta-lactam antibiotic backbone is increasingly under pressure from emerging resistance across all geographical regions, and health-care professionals in many countries are rapidly running out of effective treatment options. Even in regions that currently have only low levels of resistance, the effects of globalization are likely to increase local pressures on the beta-lactam antibiotic backbone in the near future. Therefore, clinicians are increasingly faced with a difficult balancing act: the need to prescribe adequate and appropriate antibiotic therapy while reducing the emergence of resistance and the overuse of antibiotics. In this review, we explore the burden of Gram-negative pneumonia in the critical care setting and the pressure that antibiotic resistance places on current empiric therapy regimens (and the beta-lactam antibiotic backbone) in this patient population. New treatment approaches, such as systemic and inhaled antibiotic alternatives, are on the horizon and are likely to help tackle the rising levels of beta-lactam antibiotic resistance. In the meantime, it is imperative that the beta-lactam antibiotic backbone of currently available antibiotics be supported through stringent antibiotic stewardship programs.

Risk of Hemorrhage during Needle-Based Ophthalmic Regional Anesthesia in Patients Taking Antithrombotics: A Systematic Review

BACKGROUND

Patients undergoing ophthalmic surgery are usually elderly and, due to systemic disease, may be on long-term therapy, such as antithrombotic agents. Rates of hemorrhagic complications associated with invasive procedures may be increased by the use of anticoagulants and antiplatelet agents.

OBJECTIVE

To compare the incidence of hemorrhagic complications in patients undergoing needle-based ophthalmic regional anesthesia between patients on antithrombotic therapy and those not on such therapy.

METHODS

A systematic review was conducted by two independent reviewers based on searches of Cochrane, LILACS, PubMed, Scopus, Web of Science, and the "gray" literature (Google Scholar). The end search date was May 8, 2015, across all databases.

RESULTS

Five studies met the eligibility criteria. In three studies, individual risk of bias was low, and in two of them, moderate. In all studies, no differences regarding mild to moderate incidence of hemorrhagic complications were found between patients using antithrombotics (aspirin, clopidogrel, and warfarin) and those not using them. Rates of severe hemorrhagic complication were very low (0.04%) in both groups, supporting the safety of needle blocks, even in patients using antithrombotics. High heterogeneity across studies prevented meta-analysis. Limitations to these results include low statistical power in three experimental studies and a large 95% confidence interval in the two retrospective cohorts.

CONCLUSION

In this review, none of the selected studies showed significant bleeding related to needle-based ophthalmic regional anesthesia in association with the use of aspirin, clopidogrel, or vitamin K inhibitors. Since the available data is not powerful enough to provide a reliable evaluation of the true effect of antithrombotics in this setting, new studies to address these limitations are necessary.

[Antibiotic dosing for renal function disorders and continuous renal replacement therapy]

For patients with acute kidney injury (AKI) and continuous renal replacement therapy, it is essential that the dosing of antibiotics is adequately adjusted in order to achieve an effective drug level above the minimum inhibition concentration but avoiding toxic side effects. In the selection of substances, preference should be given to antibiotics with a broad therapeutic spectrum, low incidence of side effects and, as far as possible, extrarenal elimination. Determination of serum levels should always be carried out, when this is possible. In any case, a sufficiently high loading dose should be included. An accurate as possible estimation of residual renal function and calculation of the mechanical clearance allows determination of the necessary maintenance dosage, which is acceptably accurate for clinical needs. Recent studies have shown that under modern continuous renal replacement therapy, the extent of elimination of antibiotics is regularly underestimated so that nowadays, the risk of antibiotic underdosing is higher than toxicity due to overdosing.

Pseudomonas aeruginosa ventilator-associated pneumonia management

Ventilator-associated pneumonia is the most common infection in intensive care unit patients associated with high morbidity rates and elevated economic costs; Pseudomonas aeruginosa is one of the most frequent bacteria linked with this entity, with a high attributable mortality despite adequate treatment that is increased in the presence of multiresistant strains, a situation that is becoming more common in intensive care units. In this manuscript, we review the current management of ventilator-associated pneumonia due to P. aeruginosa, the most recent antipseudomonal agents, and new adjunctive therapies that are shifting the way we treat these infections. We support early initiation of broad-spectrum antipseudomonal antibiotics in present, followed by culture-guided monotherapy de-escalation when susceptibilities are available. Future management should be directed at blocking virulence; the role of alternative strategies such as new antibiotics, nebulized treatments, and vaccines is promising.

Simulation-Based Evaluation of PK/PD Indices for Meropenem Across Patient Groups and Experimental Designs

PURPOSE

Antibiotic dose predictions based on PK/PD indices rely on that the index type and magnitude is insensitive to the pharmacokinetics (PK), the dosing regimen, and bacterial susceptibility. In this work we perform simulations to challenge these assumptions for meropenem and Pseudomonas aeruginosa.

METHODS

A published murine dose fractionation study was replicated in silico. The sensitivity of the PK/PD index towards experimental design, drug susceptibility, uncertainty in MIC and different PK profiles was evaluated.

RESULTS

The previous murine study data were well replicated with fT > MIC selected as the best predictor. However, for increased dosing frequencies fAUC/MIC was found to be more predictive and the magnitude of the index was sensitive to drug susceptibility. With human PK fT > MIC and fAUC/MIC had similar predictive capacities with preference for fT > MIC when short t1/2 and fAUC/MIC when long t1/2.

CONCLUSIONS

A longitudinal PKPD model based on in vitro data successfully predicted a previous in vivo study of meropenem. The type and magnitude of the PK/PD index were sensitive to the experimental design, the MIC and the PK. Therefore, it may be preferable to perform simulations for dose selection based on an integrated PK-PKPD model rather than using a fixed PK/PD index target.