Days spent on non-invasive ventilation support: can it determine when to initiate VV- ECMO? Observational study in a cohort of Covid-19 patients.

BACKGROUND: The study evaluates the impact of the time between commencing non-invasive ventilation (NIV) support and initiation of venovenous extracorporeal membrane oxygenation (VV-ECMO) in a cohort of critically ill patients with coronavirus disease 2019 (COVID-19) associated acute respiratory distress syndrome (ARDS). METHODS: Prospective observational study design in an intensive Care Unit (ICU) of a tertiary hospital in Barcelona (Spain). All patients requiring VV-ECMO support due to COVID-19 associated ARDS between March 2020 and January 2022 were analysed. Survival outcome was determined at 90 days after VV-ECMO initiation. Demographic data, comorbidities at ICU admission, RESP (respiratory ECMO survival prediction) score, antiviral and immunomodulatory treatments received, inflammatory biomarkers, the need for vasopressors, the thromboprophylaxis regimen received, and respiratory parameters including the length of intubation previous to ECMO and the length of each NIV support (high-flow nasal cannula, continuous positive airway pressure and bi-level positive airway pressure), were also collated in order to assess risk factors for day-90 mortality. The effect of the time lapse between NIV support and VV-ECMO on survival was evaluated using logistic regression and adjusting the association with all factors that were significant in the univariate analysis. RESULTS: Seventy-two patients finally received VV-ECMO support. At 90 days after commencing VV-ECMO 35 patients (48%) had died and 37 patients (52%) were alive. Multivariable analysis showed that at VV-ECMO initiation, age (p = 0.02), lactate (p = 0.001), and days from initiation of NIV support to starting VV-ECMO (p = 0.04) were all associated with day-90 mortality. CONCLUSIONS: In our small cohort of VV-ECMO patients with COVID-19 associated ARDS, the time spent between initiation of NIV support and VV-ECMO (together with age and lactate) appeared to be a better predictor of mortality than the time between intubation and VV-ECMO.

Pre-existing Autoantibodies Neutralizing High Concentrations of Type I Interferons in Almost 10% of COVID-19 Patients Admitted to Intensive Care in Barcelona.

BACKGROUND: It is important to predict which patients infected by SARS-CoV-2 are at higher risk of life-threatening COVID-19. Several studies suggest that neutralizing auto-antibodies (auto-Abs) against type I interferons (IFNs) are predictive of critical COVID-19 pneumonia. OBJECTIVES: We aimed to test for auto-Abs to type I IFN and describe the main characteristics of COVID-19 patients admitted to intensive care depending on whether or not these auto-Abs are present. METHODS: Retrospective analysis of all COVID-19 patients admitted to an intensive care unit (ICU) in whom samples were available, from March 2020 to March 2021, in Barcelona, Spain. RESULTS: A total of 275 (70.5%) out of 390 patients admitted to ICU were tested for type I IFNs auto-antibodies (α2 and/or ω) by ELISA, being positive in 49 (17.8%) of them. Blocking activity of plasma diluted 1/10 for high concentrations (10 ng/mL) of IFNs was proven in 26 (9.5%) patients. Almost all the patients with neutralizing auto-Abs were men (92.3%). ICU patients with positive results for neutralizing IFNs auto-Abs did not show relevant differences in demographic, comorbidities, clinical features, and mortality, when compared with those with negative results. Nevertheless, some laboratory tests (leukocytosis, neutrophilia, thrombocytosis) related with COVID-19 severity, as well as acute kidney injury (17 [65.4%] vs. 100 [40.2%]; p = 0.013) were significantly higher in patients with auto-Abs. CONCLUSION: Auto-Abs neutralizing high concentrations of type I IFNs were found in 9.5% of patients admitted to the ICU for COVID-19 pneumonia in a hospital in Barcelona. These auto-Abs should be tested early upon diagnosis of SARS-CoV-2 infection, as they account for a significant proportion of life-threatening cases.

No impact of surviving sepsis campaign care bundles in reducing sepsis-associated acute kidney injury
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BACKGROUND: The impact of Surviving Sepsis Campaign (SSC) care bundles in reducing sepsis-associated acute kidney injury (SA-AKI) was evaluated. METHODS: We conducted an observational single-center cohort study. Accomplishment of SSC care bundles was registered in all patients with severe sepsis admitted to the critical care department of a university hospital during three different periods. The main outcome measured was SA-AKI incidence defined as any worsening of AKI stage within the first 7 days from onset of sepsis. RESULTS: Among 260 patients with severe sepsis or septic shock finally meeting inclusion criteria, 82 (31.5%) patients developed SA-AKI. None of the SSC care tasks significantly decreased SA-AKI incidence, although a trend was observed with an initial better blood glucose control as well as with a more protective ventilation strategy. Hypotension requiring fluid challenge (hazard ratio (HR), 2.3; 95% confidence interval (CI), 1.2 - 4.2) and the presence of an abdominal sepsis etiology (HR, 1.8; 95% CI, 1.1 - 3.1) were independently associated with SA-AKI. Patients who developed SA-AKI had a higher 90-day mortality rate (62.2 vs. 40.4%). CONCLUSION: In a cohort of septic patients, none of the SSC care tasks significantly decreased SA-AKI incidence within the first week after onset of sepsis.
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Surgical site infection in critically ill patients with secondary and tertiary peritonitis: epidemiology, microbiology and influence in outcomes.

BACKGROUND: Surgical site infection (SSI) remains a significant problem in the postoperative period that can negatively affect clinical outcomes. Microbiology findings are typically similar to other nosocomial infections, with differences dependent on microbiology selection due to antibiotic pressure or the resident flora. However, this is poorly understood in the critical care setting. We therefore aimed to assess the incidence, epidemiology and microbiology of SSI and its association with outcomes in patients with severe peritonitis in the intensive care unit (ICU). METHODS: We prospectively studied 305 consecutive patients admitted to our surgical ICU from 2010 to 2014 with a diagnosis of secondary or tertiary peritonitis. We collected the following data: SSI diagnosis, demographics, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Simplified Acute Physiology Score (SAPS) II score, type of surgery, microbiology, antibiotic treatment and outcomes. Microbiological sampling was done by means of swabs. RESULTS: We identified 269 episodes of SSI in 162 patients (53.1%) aged 64.4 ± 14.3 years, of which 200 episodes occurred in men (64.6%). The mean APACHE II and SAPS II scores were 19.7 ± 7.8 and 36.5 ± 16.1 respectively. The mean ICU and hospital stays were 19.8 ± 24.8 and 21.7 ± 30 days respectively. Pseudomonas spp. (n = 52, 19.3%), Escherichia coli (n = 55, 20.4%) and Candida spp. (n = 46, 17.1%) were the most frequently isolated microorganisms, but gram-positive cocci (n = 80, 29.7%) were also frequent. Microorganisms isolated from SSIs were associated with a higher incidence of antibiotic resistance (64.9%) in ICU patients, but not with higher in-hospital mortality. However, patients who suffered from SSI had longer ICU admissions (odds ratio = 1.024, 95% confidence interval 1.010-1.039, P = 0.001). CONCLUSIONS: The incidence of SSI in secondary or tertiary peritonitis requiring ICU admission is very high. Physicians may consider antibiotic-resistant pathogens, gram-positive cocci and fungi when choosing empiric antibiotic treatment for SSI, although more studies are needed to confirm our results due to the inherent limitations of the microbiological sampling with swabs performed in our research. The presence of SSI may be associated with prolonged ICU stays, but without any influence on overall mortality.

Measurement of meropenem concentration in different human biological fluids by ultra-performance liquid chromatography-tandem mass spectrometry.

Meropenem is a broad-spectrum antibiotic, often used for the empirical treatment of infections in critically ill patients with acute kidney injury. Meropenem has clinically insignificant protein binding and, as a carbapenem antibiotic, shows time-dependent bacterial killing, meaning that the unbound or free antibiotic concentration in blood should be maintained above the minimal inhibitory concentration of the pathogen for at least 40 % of the dosing interval. We developed and validated simple chromatographic methods by ultra-performance liquid chromatography-tandem mass spectrometry to measure plasma, filtrate-dialysate, and urine concentrations of meropenem. Chromatographic separation was achieved using an Acquity(®) UPLC(®) BEH(TM) (2.1 × 100 mm id, 1.7 µm) reverse-phase C(18) column, with a water/acetonitrile linear gradient containing 0.1 % formic acid at a 0.4-mL/min flow rate. Meropenem and its internal standard (ertapenem) were detected by electrospray ionization mass spectrometry in positive ion multiple reaction monitoring mode. The limits of quantification were 0.27, 0.24, and 1.22 mg/L, and linearity was observed between 0.27-150, 0.24-150, and 1.22-2,000 mg/L for plasma, filtrate-dialysate, and urine samples, respectively. Coefficients of variation and relative biases were less than 13.5 and 8.0 % for all biological fluids. Recovery values were greater than 68.3 %. Evaluation of the matrix effect showed ion suppression for meropenem and ertapenem. No carry-over was observed. The validated methods are useful for both therapeutic drug monitoring and pharmacokinetic studies. It could be applied to daily clinical laboratory practice to measure the concentration of meropenem in plasma, filtrate-dialysate, and urine.

Predictive Factors of Piperacillin Exposure and the Impact on Target Attainment after Continuous Infusion Administration to Critically Ill Patients.

Critically ill patients undergo significant pathophysiological changes that affect antibiotic pharmacokinetics. Piperacillin/tazobactam administered by continuous infusion (CI) improves pharmacokinetic/pharmacodynamic (PK/PD) target attainment. This study aimed to characterize piperacillin PK after CI administration of piperacillin/tazobactam in critically ill adult patients with preserved renal function and to determine the empirical optimal dosing regimen. A total of 218 piperacillin concentrations from 106 patients were simultaneously analyzed through the population PK approach. A two-compartment linear model best described the data. Creatinine clearance (CLCR) estimated by CKD-EPI was the covariate, the most predictive factor of piperacillin clearance (CL) interindividual variability. The mean (relative standard error) parameter estimates for the final model were: CL: 12.0 L/h (6.03%); central and peripheral compartment distribution volumes: 20.7 L (8.94%) and 62.4 L (50.80%), respectively; intercompartmental clearance: 4.8 L/h (26.4%). For the PK/PD target of 100% fT>1×MIC, 12 g of piperacillin provide a probability of target attainment > 90% for MIC < 16 mg/L, regardless of CLCR, but higher doses are needed for MIC = 16 mg/L when CLCR > 100 mL/min. For 100% fT>4×MIC, the highest dose (24 g/24 h) was not sufficient to ensure adequate exposure, except for MICs of 1 and 4 mg/L. Our model can be used as a support tool for initial dose guidance and during therapeutic drug monitoring.

Sepsis-associated acute kidney injury: consensus report of the 28th Acute Disease Quality Initiative workgroup.

Sepsis-associated acute kidney injury (SA-AKI) is common in critically ill patients and is strongly associated with adverse outcomes, including an increased risk of chronic kidney disease, cardiovascular events and death. The pathophysiology of SA-AKI remains elusive, although microcirculatory dysfunction, cellular metabolic reprogramming and dysregulated inflammatory responses have been implicated in preclinical studies. SA-AKI is best defined as the occurrence of AKI within 7 days of sepsis onset (diagnosed according to Kidney Disease Improving Global Outcome criteria and Sepsis 3 criteria, respectively). Improving outcomes in SA-AKI is challenging, as patients can present with either clinical or subclinical AKI. Early identification of patients at risk of AKI, or at risk of progressing to severe and/or persistent AKI, is crucial to the timely initiation of adequate supportive measures, including limiting further insults to the kidney. Accordingly, the discovery of biomarkers associated with AKI that can aid in early diagnosis is an area of intensive investigation. Additionally, high-quality evidence on best-practice care of patients with AKI, sepsis and SA-AKI has continued to accrue. Although specific therapeutic options are limited, several clinical trials have evaluated the use of care bundles and extracorporeal techniques as potential therapeutic approaches. Here we provide graded recommendations for managing SA-AKI and highlight priorities for future research.

Individual outcome prediction models for patients with COVID-19 based on their first day of admission to the intensive care unit.

BACKGROUND: Currently, good prognosis and management of critically ill patients with COVID-19 are crucial for developing disease management guidelines and providing a viable healthcare system. We aimed to propose individual outcome prediction models based on binary logistic regression (BLR) and artificial neural network (ANN) analyses of data collected in the first 24 h of intensive care unit (ICU) admission for patients with COVID-19 infection. We also analysed different variables for ICU patients who survived and those who died. METHODS: Data from 326 critically ill patients with COVID-19 were collected. Data were captured on laboratory variables, demographics, comorbidities, symptoms and hospital stay related information. These data were compared with patient outcomes (survivor and non-survivor patients). BLR was assessed using the Wald Forward Stepwise method, and the ANN model was constructed using multilayer perceptron architecture. RESULTS: The area under the receiver operating characteristic curve of the ANN model was significantly larger than the BLR model (0.917 vs 0.810; p < 0.001) for predicting individual outcomes. In addition, ANN model presented similar negative predictive value than the BLR model (95.9% vs 94.8%). Variables such as age, pH, potassium ion, partial pressure of oxygen, and chloride were present in both models and they were significant predictors of death in COVID-19 patients. CONCLUSIONS: Our study could provide helpful information for other hospitals to develop their own individual outcome prediction models based, mainly, on laboratory variables. Furthermore, it offers valuable information on which variables could predict a fatal outcome for ICU patients with COVID-19.

Outcomes of COVID-19 Patients Admitted to the Intermediate Respiratory Care Unit: Non-Invasive Respiratory Therapy in a Sequential Protocol.

The intermediate respiratory care units (IRCUs) have a pivotal role managing escalation and de-escalation between the general wards and the intensive care units (ICUs). Since the COVID-19 pandemic began, the early detection of patients that could improve on non-invasive respiratory therapies (NRTs) in IRCUs without invasive approaches is crucial to ensure proper medical management and optimize limiting ICU resources. The aim of this study was to assess factors associated with survival, ICU admission and intubation likelihood in COVID-19 patients admitted to IRCUs. Observational retrospective study in consecutive patients admitted to the IRCU of a tertiary hospital from March 2020 to April 2021. Inclusion criteria: hypoxemic respiratory failure (SpO2 ≤ 94% and/or respiratory rate ≥ 25 rpm with FiO2 > 50% supplementary oxygen) due to acute COVID-19 infection. Demographic, comorbidities, clinical and analytical data, and medical and NRT data were collected at IRCU admission. Multivariate logistic regression models assessed factors associated with survival, ICU admission, and intubation. From 679 patients, 79 patients (12%) had an order to not do intubation. From the remaining 600 (88%), 81% survived, 41% needed ICU admission and 37% required intubation. In the IRCU, 51% required non-invasive ventilation (NIV group) and 49% did not (non-NIV group). Older age and lack of corticosteroid treatment were associated with higher mortality and intubation risk in the scheme, which could be more beneficial in severe forms. Initial NIV does not always mean worse outcomes.

Continuous Infusion of Piperacillin/Tazobactam and Meropenem in ICU Patients Without Renal Dysfunction: Are Patients at Risk of Underexposure?

BACKGROUND AND OBJECTIVES: Morbidity and mortality from serious infections are common in intensive care units (ICUs). The appropriateness of the antibiotic treatment is essential to combat sepsis. We aimed to evaluate pharmacokinetic/pharmacodynamic target attainment of meropenem and piperacillin/tazobactam administered at standard total daily dose as continuous infusion in critically ill patients without renal dysfunction and to identify risk factors of non-pharmacokinetic/pharmacodynamic target attainment. RESULTS: We included 118 patients (149 concentrations), 47% had microorganism isolation. Minimum inhibitory concentration (MIC) [median (interquartile range, IQR) values in isolated pathogens were: meropenem: 0.05 (0.02-0.12) mg/l; piperacillin: 3 (1-4) mg/l]. Pharmacokinetic/pharmacodynamic target attainments (100%fCss≥1xMIC, 100%fCss≥4xMIC and 100%fCss ≥ 8xMIC, respectively) were: 100%, 96.15%, 96.15% (meropenem) and 95.56%, 91.11%, 62.22% (piperacillin) for actual MIC; 98.11%, 71.70%, 47.17% (meropenem, MIC 2 mg/l), 95.83%, 44.79%, 6.25% (piperacillin, MIC 8 mg/l), 83.33%, 6.25%, 1.04% (piperacillin, MIC 16 mg/l) for EUCAST breakpoint of Enterobacteriaceae spp. and Pseudomonas spp. Multivariable linear analysis identified creatinine clearance (CrCL) as a predictive factor of free antibiotic concentrations (fCss) of both therapies (meropenem [ß = - 0.01 (95% CI - 0.02 to - 0.0; p = 0.043)] and piperacillin [ß = - 0.01 (95% CI - 0.02 to 0.01, p < 0.001)]). Neurocritical status was associated with lower piperacillin fCss [ß = - 0.36 (95% CI - 0.61 to - 0.11; p = 0.005)]. CONCLUSION: Standard total daily dose of meropenem allowed achieving pharmacokinetic/pharmacodynamic target attainments in ICU patients without renal dysfunction. Higher doses of piperacillin/tazobactam would be needed to cover microorganisms with MIC > 8 mg/l. CrCL was the most powerful factor predictive of fCss in both therapies.

COVID-19-associated acute kidney injury: consensus report of the 25th Acute Disease Quality Initiative (ADQI) Workgroup.

Kidney involvement in patients with coronavirus disease 2019 (COVID-19) is common, and can range from the presence of proteinuria and haematuria to acute kidney injury (AKI) requiring renal replacement therapy (RRT; also known as kidney replacement therapy). COVID-19-associated AKI (COVID-19 AKI) is associated with high mortality and serves as an independent risk factor for all-cause in-hospital death in patients with COVID-19. The pathophysiology and mechanisms of AKI in patients with COVID-19 have not been fully elucidated and seem to be multifactorial, in keeping with the pathophysiology of AKI in other patients who are critically ill. Little is known about the prevention and management of COVID-19 AKI. The emergence of regional 'surges' in COVID-19 cases can limit hospital resources, including dialysis availability and supplies; thus, careful daily assessment of available resources is needed. In this Consensus Statement, the Acute Disease Quality Initiative provides recommendations for the diagnosis, prevention and management of COVID-19 AKI based on current literature. We also make recommendations for areas of future research, which are aimed at improving understanding of the underlying processes and improving outcomes for patients with COVID-19 AKI.

Publisher Correction: COVID-19-associated acute kidney injury: consensus report of the 25th Acute Disease Quality Initiative (ADQI) Workgroup.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Beneficial effect of corticosteroids in preventing mortality in patients receiving tocilizumab to treat severe COVID-19 illness.

OBJECTIVES: To assess the characteristics and risk factors for mortality in patients with severe coronavirus disease-2019 (COVID-19) treated with tocilizumab (TCZ), alone or in combination with corticosteroids (CS). METHODS: From March 17 to April 7, 2020, a real-world observational retrospective analysis of consecutive hospitalized adult patients receiving TCZ to treat severe COVID-19 was conducted at our 750-bed university hospital. The main outcome was all-cause in-hospital mortality. RESULTS: A total of 1,092 patients with COVID-19 were admitted during the study period. Of them, 186 (17%) were treated with TCZ, of which 129 (87.8%) in combination with CS. Of the total 186 patients, 155 (83.3 %) patients were receiving noninvasive ventilation when TCZ was initiated. Mean time from symptoms onset and hospital admission to TCZ use was 12 (±4.3) and 4.3 days (±3.4), respectively. Overall, 147 (79%) survived and 39 (21%) died. By multivariate analysis, mortality was associated with older age (HR = 1.09, p < 0.001), chronic heart failure (HR = 4.4, p = 0.003), and chronic liver disease (HR = 4.69, p = 0.004). The use of CS, in combination with TCZ, was identified as a protective factor against mortality (HR = 0.26, p < 0.001) in such severe COVID-19 patients receiving TCZ. No serious superinfections were observed after a 30-day follow-up. CONCLUSIONS: In patients with severe COVID-19 receiving TCZ due to systemic host-immune inflammatory response syndrome, the use of CS in addition to TCZ therapy, showed a beneficial effect in preventing in-hospital mortality.

Factors Associated with the Development of Tertiary Peritonitis in Critically Ill Patients.

BACKGROUND: Critically ill surgical patients remain at a high risk of adverse outcomes as a result of secondary peritonitis (SP). The risk is even higher if tertiary peritonitis (TP) develops. Factors related to the development of TP, however, are scarce in the literature. The main aim of our study was to identify factors associated with the development of TP in patients with SP in the intensive care unit (ICU), and also to report differences in microbiologic patterns and antibiotic therapy in patients with the two conditions. PATIENTS AND METHODS: A prospective, observational study was conducted at our institution from 2010 to 2014. Baseline characteristics on admission, outcomes, microbiologic results, and antibiotic therapy were recorded for analysis. RESULTS: We included 343 patients with SP, of whom TP developed in 185 (53.9%). Almost two-thirds (64.4%) were male; mean age was 63.7 ± 14.3 years, and mean APACHE was 19.4 ± 7.8. In-hospital death was 42.6% (146). Multivariable analysis showed that longer ICU stay (odds ratio [OR]: 1.019; 95% confidence interval [CI]: 1.004-1.034; p = 0.010), urgent operation on hospital admission (OR: 3.247; 95% CI: 1.392-7.575; p = 0.006), total parenteral nutrition (TPN) (OR: 3.079; 95% CI: 1.535-6.177; p = 0.002) and stomach-duodenum as primary infection site (OR: 4.818; 95% CI: 1.429-16.247; p = 0.011) were factors associated with the development of TP, whereas patients with localized peritonitis were less prone to have TP develop (OR: 0.308; 95% CI: 0.152-0.624; p = 0.001). Higher incidences of Candida spp. (OR: 1.275; 95% CI: 1.096-1.789; p = 0.016), Enterococcus faecium (OR: 1.085; 95% CI: 1.018-1.400; p = 0.002), and Enterococcus spp. (OR: 1.370; 95% CI: 1.139-1.989; p = 0.047) were found in TP, and higher rates of cephalosporin use in SP (OR: 3.51; 95% CI: 1.139-10.817; p = 0.035). CONCLUSIONS: Complicated peritonitis remains a cause of a high numbers of deaths in the ICU. The need for TPN, urgent operation on hospital admission, and particularly surgical procedures in the proximal gastrointestinal tract were factors associated with development of TP and may potentially help to identify patients with SP at risk for development of TP. Physicians should be aware concerning multi-drug-resistant germs when treating these patients.

Clinical variables associated with poor outcome from sepsis-associated acute kidney injury and the relationship with timing of initiation of renal replacement therapy.

PURPOSE: Identify clinical variables associated with mortality in patients with sepsis-associated acute kidney injury (SA-AKI) receiving continuous renal replacement therapy (CRRT) and examine timing of initiation of CRRT in reference to those variables identified. METHODS: Retrospective study conducted at two tertiary care hospitals including 939 septic shock patients with SA-AKI who received CRRT in the intensive care unit (ICU). Cox regression models were used to identify variables associated with 90-day mortality. Timing of CRRT initiation was assessed in relationship to significant clinical variables identified. RESULTS: Overall 90-day mortality was 62.9%. Variables prior to CRRT associated with 90-day mortality included: age (aHR, 1.02; 95%CI, 1.01-1.02, p<000.1), APS-III score (1.01, 1.0-1.0, p<0.048), days from hospital admission to CRRT initiation (1.01, 1.0-1.0, p<0.01), blood urea nitrogen (1.01, 1.0-1.0, p<0.04), medical admission (1.76, 1.5-2.1, p<0.0001), creatinine (0.99, 0.9-1.0, p<0.001), and urine output (0.77, 0.6-0.9, p=0.049). In patients with advanced SA-AKI at ICU admission receiving CRRT within the first 5days (n=433), urine output during the 24h prior to CRRT initiation was a strong predictor of survival (2.6, 1.6-4.3, p<0.001). CONCLUSIONS: In patients with SA-AKI, survival is lower when CRRT is started in the setting of low urine output.

Development and validation of a measurement procedure based on ultra-high performance liquid chromatography-tandem mass spectrometry for simultaneous measurement of ß-lactam antibiotic concentration in human plasma.

BACKGROUND: The administration of ß-lactam antibiotics in continuous infusion could let optimize the pharmacokinetic/pharmacodynamic parameters, especially in the treatment of serious bacterial infections. In this context, and also due to variability in their plasmatic concentrations, therapeutic drug monitoring (TDM) may be useful to optimize dosing and, therefore, be useful for the clinicians. MATERIAL AND METHODS: We developed and validated a measurement procedure based on ultra-high performance liquid chromatography-tandem mass spectrometry for simultaneous measurement of amoxicillin, ampicillin, cloxacillin, piperacillin, cefepime, ceftazidime, cefuroxime, aztreonam and meropenem concentrations in plasma. The chromatographic separation was achieved using an Acquity®-UPLC® BEH™ (2.1×100mm id, 1.7µm) reverse-phase C18 column, with a water/acetonitrile linear gradient containing 0.1% formic acid at a 0.4mL/min flow rate. ß-Lactam antibiotics and their internal standards were detected by electrospray ionization mass spectrometry in multiple reaction monitoring mode. RESULTS: Chromatography run time was 7.0min and ß-lactam antibiotics eluted at retention times ranging between 1.08 and 1.91min. The lower limits of quantification were between 0.50 and 1.00mg/L. Coefficients of variation and relative bias absolute values were <13.3% and 14.7%, respectively. Recovery values ranged from 55.7% to 84.8%. Evaluation of the matrix effect showed ion enhancement for all antibiotics. No interferences or carry-over were observed. CONCLUSIONS: Our measurement procedure could be applied to daily clinical laboratory practice to measure the concentration of ß-lactam antibiotics in plasma, for instance in patients with bone and joint infections and critically ill patients.