Diagnostic yield of routine daily blood culture in patients on veno-arterial extracorporeal membrane oxygenation

Nosocomial Infections in Adults Receiving Extracorporeal Membrane Oxygenation: A Review for Infectious Diseases Clinicians

Over the past 10 years, there has been a rapid expansion in the use of extracorporeal membrane oxygenation (ECMO) in the care of patients with refractory cardiac or respiratory failure. Infectious diseases clinicians must reconcile conflicting evidence from limited studies as they develop practices at their own institutions, which has resulted in considerably different practices globally. This review describes infection control and prevention as well as antimicrobial prophylaxis strategies in this population. Data on diagnostics and treatment for patients receiving ECMO with a focus on diagnostic and antimicrobial stewardship is then examined. This review summarizes gaps in the current ECMO literature and proposes future needs, including developing clear definitions for infections and encouraging transparent reporting of practices at individual facilities in future clinical trials.

Upper gastrointestinal bleeding on veno-arterial extracorporeal membrane oxygenation support

INTRODUCTION

Patients on veno-arterial extracorporeal membrane oxygenation (V-A ECMO) support are at a high risk of hemorrhagic complications, including upper gastrointestinal bleeding (UGIB). The objective of this study was to evaluate the incidence and impact of this complication in V-A ECMO patients.

MATERIALS AND METHODS

A retrospective single-center study (2013-2017) was conducted on V-A ECMO patients, excluding those who died within 24 h. All patients with suspected UGIB underwent esophagogastroduodenoscopy (EGD) and were analyzed and compared to the remainder of the cohort, from the initiation of ECMO until 5 days after explantation.

RESULTS

A total of 150 V-A ECMO cases (65 after cardiac surgery and 85 due to medical etiology) were included. 90% of the patients received prophylactic proton pump inhibitor therapy and enteral nutrition. Thirty-one patients underwent EGD for suspected UGIB, with 16 confirmed cases of UGIB. The incidence was 10.7%, with a median occurrence at 10 [7-17] days. There were no significant differences in clinical or biological characteristics on the day of EGD. However, patients with UGIB had significant increases in packed red blood cells and fresh frozen plasma needs, mechanical ventilation duration and V-A ECMO duration, as well as in length of intensive care unit and hospital stays. There was no significant difference in mortality. The only independent risk factor of UGIB was a history of peptic ulcer (OR = 7.32; 95% CI [1.07-50.01], p = 0.042).

CONCLUSION

UGIB occurred in at least 1 out of 10 cases of V-A ECMO patients, with significant consequences on healthcare resources. Enteral nutrition and proton pump inhibitor prophylaxis did not appear to protect V-A ECMO patients. Further studies should assess their real benefits in these patients with high risk of hemorrhage.

The utility of sepsis scores for predicting blood stream infections in extracorporeal membrane oxygenation

INTRODUCTION

Extracorporeal membrane oxygenation (ECMO) is an increasingly used modality of life support with high risk for nosocomial infections. The accuracy of sepsis prediction tools in identifying blood stream infections (BSI) in this population is unknown as measurement of multiple variables commonly associated with infection are altered by the circuit.

METHODS

This study compares all blood stream infections for patients receiving ECMO between January 2012 and December 2020 to timepoints when blood cultures were negative using the Sequential Organ Failure Assessment (SOFA), Logistic Organ Dysfunction Score (LODS), American Burn Association Sepsis Criteria (ABA), Systemic Inflammatory Response Syndrome (SIRS) scores.

RESULTS

Of the 220 patients who received ECMO during the study period, 40 (18%) had 51 blood stream infections and were included in this study. Gram-positive infections composed 57% (n = 29) of infections with E. faecalis (n = 12, 24%) being the most common organism isolated. There were no significant differences in sepsis prediction scores at the time of infection compared to infection-free time points for SOFA (median (IQR) 7 (5-9) vs. 6 (5-8), p = 0.22), LODS (median (IQR) 12 (10-14) vs. 12 (10-13), p = 0.28), ABA (median (IQR) 2 (1-3) vs. 2 (1-3) p = 0.75), or SIRS (median (IQR) 3 (2-3) vs. 3 (2-3), p = 0.20).

CONCLUSIONS

Our data shows that previously published sepsis scores are elevated throughout a patient's ECMO course, and do not correlate with bacteremia. Better predictive tools are needed to determine the appropriate timing for blood cultures in this population.

Infectious diseases and infection control prevention strategies in adult and pediatric population on ECMO

As survival after ECMO improves and use of ECMO support increases in both pediatric and adult population, there is a need to focus on both the morbidities and complications associated with ECMO and how to manage and prevent them. Infectious complications during ECMO often have a significant clinical impact, resulting in increased morbidity or mortality irrespective of the underlying etiology necessitating cardiorespiratory support. In this review article, we discuss the prevention, management, challenges, and differences of infectious complications in adult and pediatric patients receiving ECMO support.

A systematic review of variability in the reporting of extracorporeal membrane oxygenation-associated infections and recommendations for standardization

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) utilization has surged in recent years, particularly amidst the COVID-19 pandemic, yet standardization of ECMO-associated infection (EAI) reporting remains lacking.

METHODS

This systematic review assessed 60 studies from 2018 to 2023 in PubMed, which used key words related to EAIs. Adherence to reporting data elements that may bias reporting, including the use of standardized rates of infections per 1,000 patient days, describing the use of antimicrobial prophylaxis, infection control, and culture practices, describing the definitions for infection by site, and listing pathogens by infection site were evaluated by study.

RESULTS

Our review revealed considerable heterogeneity in data elements and infection definitions. While 51 (85%) studies reported definition by site, only 17 (28%) reported infection control practices, and only 5 (8%) studies adhered to all the identified essential reporting elements. Variation in infection rates was also evident across the definitions, with studies using their own definition having the greatest variability in reported infection rates. Microbiological differences by geographic region further underscored the need for standardized reporting and challenges with generalizability in the EAI literature.

CONCLUSIONS

Our findings underscore the imperative for consensus on ECMO infection definitions and transparent reporting practices to facilitate meaningful comparisons and advance patient care protocols.

Biofilm Assessment and Metagenomic Analysis of Venoarterial Extracorporeal Membrane Oxygenation Cannulas and Membrane Oxygenators

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) exposes the patient to infectious complications related to the cannulas or the site of insertion. The aim of the current study was to investigate and compare the prevalence of cannula and membrane oxygenators colonization using three different methods: microbiological culture, scanning electron microscopy, and metagenomic (rRNA 16S analysis). A monocentric prospective study was conducted between December 2017 and June 2018. Consecutive patients undergoing VA-ECMO support for refractory cardiac arrest or cardiogenic shock were included. Ten patients were included with a median age of 64 (52-62) years. Venoarterial extracorporeal membrane oxygenation was inserted for refractory cardiac arrest in five (50%), cardiogenic shock in four (40%), and self-poisoning in one (10%) cases. Microbiological culture of all (8/8, 100%) membrane oxygenators was negative, whereas all (10/10, 100%) were colonized by biofilm, and eight (8/9, 89%) presented bacterial DNA. Three (3/9, 33%) arterial and venous cannulas were positive in culture and seven (7/9, 78%) were colonized by biofilm, respectively. Seven (7/9, 78%) arterial and four (4/9, 44%) venous cannulas presented bacterial DNA. Colonization of cannulas and membranes is more frequent when assessed by electron microscopy or metagenomic analysis than with culture. Membrane oxygenators are more often colonized than cannulas.

The impact of extracorporeal membrane oxygenation on antifungal pharmacokinetics: A systematic review

BACKGROUND AND OBJECTIVE

The use of extracorporeal membrane oxygenation (ECMO) as a cardiocirculatory or respiratory support has tremendously increased in critically ill patients. In the setting of ECMO support, invasive fungal infections are a severe cause of morbidity and mortality. This vulnerable population is at risk of suboptimal antifungal exposure due to an increased volume of distribution (Vd), drug sequestration and decreased clearance. Here, we aimed to summarize ex-vivo and clinical studies on the potential impact of ECMO on the pharmacokinetics (PK) of antifungal agents and dosing requirements.

METHODS

A systematic search of the literature within electronic databases PubMed and EMBASE was conducted from database inception to 30 April 2023. Inclusion criteria were as follows: critically ill patients receiving ECMO regardless of age and reporting at least one PK parameter.

RESULTS

Thirty-six studies met inclusion criteria, including seven ex-vivo experiments and 29 clinical studies evaluating three classes of antifungals: polyenes, triazoles and echinocandins. Based on the available ex-vivo PK data, we found a significant sequestration of highly lipophilic and protein-bound antifungals within the ECMO circuit such as voriconazole, posaconazole and micafungin but the PK of several antifungals remains to be addressed such as amphotericin B, isavuconazole and anidulafungin. Most clinical studies have shown increased Vd of some antifungals like fluconazole and micafungin, particularly in the pediatric population. Conflicting data exist about caspofungin exposure.

CONCLUSIONS

The available literature on the antifungal PK changes in ECMO setting is scarce. Whenever possible, therapeutic drug monitoring is highly advised to personalize antifungal therapy.

Infection in ECMO patients: Changes in epidemiology, diagnosis and prevention

Patients with prolonged duration of extracorporeal membrane oxygenation support (ECMO) are a vulnerable population for sepsis, particularly ventilator-associated pneumonia and bloodstream infections. Rates differ between venous-arterial and venous-venous ECMO patients and according to the cannulation technique used. The presence of particular organisms depends on local epidemiology, antibiotic exposure, and the duration of the intervention; patients undergoing ECMO for more than three weeks present a high risk of persistent candidemia. Recognizing predisposing factors, and establishing the best preventive interventions and therapeutic choices are critical to optimizing the management of these complications. Infection control practices, including shortening the period of the indwelling devices, and reducing antibiotic exposure, must be followed meticulously. Innovations in oxygenator membranes require an updated approach. Hand hygiene and avoiding breaking the circuit-oxygenator sterility are cornerstones. ECMO management would benefit from clearer definitions, optimization of infection control strategies, and updated infectious clinical practice guidelines.

The utility of procalcitonin for identifying secondary infections in patients with influenza or COVID-19 receiving extracorporeal membrane oxygenation

Background

Identifying secondary infections in patients receiving extracorporeal membrane oxygenation (ECMO) presents challenges due to the ECMO circuit's influence on traditional signs of infection.

Objectives

This study evaluates procalcitonin as a diagnostic marker for secondary infections in patients receiving ECMO with influenza or COVID-19 infection.

Design

Single-center retrospective cohort study.

Methods

All adult patients receiving veno-venous ECMO with underlying influenza or COVID-19 from November 2017 to October 2021 were included. Patient demographics, time receiving ECMO, culture data, and procalcitonin levels were examined. The first procalcitonin within 3 days of infection was compared to negative workups that were collected at least 10 days from the last positive culture. Furthermore, we compared procalcitonin levels by the type of pathogen and site of infection.

Results

In this study, 84 patients with influenza or COVID-19 who received ECMO were included. A total of 276 procalcitonin labs were ordered in this cohort, with 33/92 (36%) of the secondary infections having an associated procalcitonin value. When comparing procalcitonin levels, there was no significant difference between the infection and negative workup groups [1 ng/mL (interquartile ranges, IQR: 0.4-1.2) versus 1.3 (0.5-4.3), p = 0.19]. Using 0.5 ng/mL as the cut-off, the sensitivity of procalcitonin was 67% and the specificity was 30%. In our cohort, the positive predictive value of procalcitonin was 14.5% and the negative predictive value was 84%. There was no difference in procalcitonin by type of organism or site of infection. Procalcitonin levels did not routinely decline even after an infection was identified.

Conclusion

While procalcitonin is a proposed potential diagnostic marker for secondary infections in patients receiving ECMO, this single-center study demonstrated low sensitivity and specificity of procalcitonin in identifying secondary infections. Furthermore, there was no association of procalcitonin levels with etiology of infection when one was present. Procalcitonin should be used cautiously in identifying infections in veno-venous ECMO.

Fever and Leukocytosis Are Poor Predictors of Bacterial Coinfection in Patients With COVID-19 and Influenza Who Are Receiving Extracorporeal Membrane Oxygenation

Background

Fever and leukocytosis are 2 parameters commonly cited in clinical practice as indications to perform an infectious workup in patients receiving extracorporeal membrane oxygenation (ECMO), but their utility is unknown.

Methods

All patients who received ECMO between December 2014 and December 2020 with influenza or COVID-19 were included in this retrospective cohort study. Cultures were included if they were drawn from patients without signs of decompensation. Maximum temperature and white blood cell count were recorded on the day of culture collection. Workups with infections were compared with those that were negative.

Results

Of the 137 infectious workups in this 45-patient cohort, 86 (63%) were performed in patients with no signs of decompensation, totaling 165 cultures. These workups yielded 10 (12%) true infections. There were no differences in median (IQR) temperature (100.4 °F [100.2-100.8] vs 100.4 °F [99.3-100.9], P = .90) or white blood cell count (18.6 cells/mL [16.8-20.1] vs 16.7 cells/mL [12.8-22.3], P = .90) between those with and without infections.

Conclusions

In patients with influenza or COVID-19 who require ECMO, fever and leukocytosis were common indications for infectious workups, yet results were frequently negative. Despite their use in clinical practice, fever and leukocytosis are not reliable indicators of infection in patients who are hemodynamically stable and receiving ECMO.

First nosocomial infections in children supported by veno-arterial extracorporeal membrane oxygenation (VA-ECMO)

BACKGROUND

Veno-arterial Extracorporeal Membrane Oxygenation (VA-ECMO) is a standard procedure for patient with refractory shock in Pediatric Intensive Care Unit (PICU). There is a paucity of data on the time relationship between VA-ECMO support, nosocomial infection occurrence, and PICU length of stay (LOS). The aim of this study was to determine the characteristics and impact of ECMO-related infections.

METHODS

This is a retrospective study from 01/2008 to 12/2014, enrolling children with a VA-ECMO support for > 6 h. We recorded the first PICU infection during the VA-ECMO run, defined as a positive microbiological sample with clinical signs of infection or clinical signs of severe infection without positive sample.

RESULTS

During the study period, 41 patients (25/41 male) were included, with a median age of 41.2 months (IQR 12.9-89.9) and a 53% mortality rate. Median time on VA-ECMO was 4.2 d (IQR 2-7.1), median PICU LOS was 14.7 d (IQR 4,7-26,9). Overall, 34% patients developed an infection, with an incidence of 60/1000 VA-ECMO days. Median time to first infection was 4 d (IQR 3-5), with Pseudomonas spp. being the most commonly detected microorganism (42%). Infected sites were ventilator-associated pneumonia (9/14), sternotomy infection (2/14), bloodstream (2/14) and urinary tract infections (1/14). Longer VA-ECMO support (> 5 d) (OR 5.9 (CI 95% 1.4-24.6; p = 0.01) and longer PICU stay (> 14 d) (OR 12 (95% CI 2.2-65.5; p = 0.004) were associated with infection.

CONCLUSION

In this single-center study, we underlined the high proportion and early occurrence of infections in patient on VA-ECMO, mostly in the first week. As infection was an early event, it may prolong the duration of VA-ECMO support and PICU LOS. Further research is needed to better understand the impact of infections on VA-ECMO and develop prevention strategies.

Nosocomial infections during extracorporeal membrane oxygenation

PURPOSE OF THE REVIEW

The aim of this review is to present the latest evidence regarding the prevention, diagnosis and treatment of nosocomial infections during extracorporeal membrane oxygenation (ECMO) support.

RECENT FINDINGS

New descriptive data from the Extracorporeal Life Support Organisation (ELSO) registry and single centre studies have been published. In parallel, there is an increase in the availability of evidence about the diagnostic accuracy of infection markers, yield of routine cultures, effectivity of antibiotic prophylaxis and other preventive measures.

SUMMARY

ECMO is a rescue therapy for severe hemodynamic or respiratory failure. Nosocomial infections on ECMO support are frequent (infection rate ranging between 20.5% to more than 50% of ECMO runs) and have impact in survival, with reported increases in the risk of death up to 63% in infected patients. However, diagnosis and treatment are challenging, as the unique relationship between patient and circuit may act as a confounder for infection and exacerbate the variability of antibiotic pharmacokinetics in critical illness. Clinical practice regarding antibiotic treatment and infection prevention is not yet supported by high-quality evidence.

Population Pharmacokinetics of Amikacin in Patients on Veno-Arterial Extracorporeal Membrane Oxygenation

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) support leads to complex pharmacokinetic alterations, whereas adequate drug dosing is paramount for efficacy and absence of toxicity in critically ill patients. Amikacin is a major antibiotic used in nosocomial sepsis, especially for these patients. We aimed to describe amikacin pharmacokinetics on V-A ECMO support and to determine relevant variables to improve its dosing. All critically ill patients requiring empirical antimicrobial therapy, including amikacin for nosocomial sepsis supported or not by V-A ECMO, were included in a prospective population pharmacokinetic study. This population pharmacokinetic analysis was built with a dedicated software, and Monte Carlo simulations were performed to identify doses achieving therapeutic plasma concentrations. Thirty-nine patients were included (control n = 15, V-A ECMO n = 24); 215 plasma assays were performed and used for the modeling process. Patients received 29 (24–33) and 32 (30–35) mg/kg of amikacin in control and ECMO groups, respectively. Data were best described by a two-compartment model with first-order elimination. Inter-individual variabilities were observed on clearance, central compartment volume (V₁)_, and peripherical compartment volume (V₂). Three significant covariates explained these variabilities: Kidney Disease Improving Global Outcomes (KDIGO) stage on amikacin clearance, total body weight on V_1, and ECMO support on V₂. Our simulations showed that the adequate dosage of amikacin was 40 mg/kg in KDIGO stage 0 patients, while 25 mg/kg in KDIGO stage 3 patients was relevant. V-A ECMO support had only a secondary impact on amikacin pharmacokinetics, as compared to acute kidney injury.