Prevalence and Risk Factors for Weaning Failure From Venovenous Extracorporeal Membrane Oxygenation in Patients With Severe Acute Respiratory Insufficiency

OBJECTIVE

Analysis of the prevalence and risk factors for weaning failure from venovenous extracorporeal membrane oxygenation (VV-ECMO) in patients with severe acute respiratory insufficiency.

DESIGN

Single-center retrospective observational study.

SETTING

Sixteen beds medical ICU at the University Hospital Regensburg.

PATIENTS

Two hundred twenty-seven patients with severe acute respiratory insufficiency requiring VV-ECMO support between October 2011 and December 2017.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients meeting our ECMO weaning criteria (Sp o2 ≥ 90% with F io2 ≤ 0.4 or Pa o2 /F io2 > 150 mm Hg, pH = 7.35-7.45, positive end-expiratory pressure ≤ 10 cm H 2 O, driving pressure < 15 cm H 2 O, respiratory rate < 30/min, tidal volume > 5 mL/kg, ECMO bloodflow ≈ 1. 5 L/min, sweep gas flow ≈ 1 L/min, heart rate < 120/min, systolic blood pressure 90-160 mm Hg, norepinephrine < 0.2 µg/[kg*min]) underwent an ECMO weaning trial (EWT) with pausing sweep gas flow. Arterial blood gas analysis, respiratory and ventilator parameters were recorded prior, during, and after EWTs. Baseline data, including demographics, vitals, respiratory, ventilator, and laboratory parameters were recorded at the time of cannulation. One hundred seventy-nine of 227 (79%) patients were successfully decannulated. Ten patients (4%) underwent prolonged weaning of at least three failed EWTs before successful decannulation. The respiratory rate (19/min vs 16/min, p = 0.002) and Pa co2 (44 mm Hg vs 40 mm Hg, p = 0.003) were higher before failed than successful EWTs. Both parameters were risk factors for ECMO weaning failure (Pa co2 : odds ratio [OR] 1.05; 95% CI, 1.001-1.10; p = 0.045; respiratory rate: OR 1.10; 95% CI, 1.04-1.15; p < 0.001) in multivariable analysis. The rapid shallow breathing index [42 (1/L*min), vs 35 (1/L*min), p = 0.052) was higher before failed than successful EWTs. The decline of Sa o2 and Pa o2 /F io2 during EWTs was higher in failed than successful trials.

CONCLUSIONS

Seventy-nine percent of patients were successfully decannulated with only 4% needing prolonged ECMO weaning. Before EWT only parameters of impaired ventilation (insufficient decarboxylation, higher respiratory rate) but not of oxygenation were predictive for weaning failure, whereas during EWT-impaired oxygenation was associated with weaning failure.

Bilateral Femoral Cannulation Is Associated With Reduced Severe Limb Ischemia-Related Complications Compared With Unilateral Femoral Cannulation in Adult Peripheral Venoarterial Extracorporeal Membrane Oxygenation: Results From the Extracorporeal Life Support Registry

OBJECTIVES

Peripheral venoarterial extracorporeal membrane oxygenation (ECMO) with femoral access is obtained through unilateral or bilateral groin cannulation. Whether one cannulation strategy is associated with a lower risk for limb ischemia remains unknown. We aim to assess if one strategy is preferable.

DESIGN

A retrospective cohort study based on the Extracorporeal Life Support Organization registry.

SETTING

ECMO centers worldwide included in the Extracorporeal Life Support Organization registry.

PATIENTS

All adult patients (≥ 18 yr) who received peripheral venoarterial ECMO with femoral access and were included from 2014 to 2020.

INTERVENTIONS

Unilateral or bilateral femoral cannulation.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the occurrence of limb ischemia defined as a composite endpoint including the need for a distal perfusion cannula (DPC) after 6 hours from implantation, compartment syndrome/fasciotomy, amputation, revascularization, and thrombectomy. Secondary endpoints included bleeding at the peripheral cannulation site, need for vessel repair, vessel repair after decannulation, and in-hospital death. Propensity score matching was performed to account for confounders. Overall, 19,093 patients underwent peripheral venoarterial ECMO through unilateral ( n = 11,965) or bilateral ( n = 7,128) femoral cannulation. Limb ischemia requiring any intervention was not different between both groups (bilateral vs unilateral: odds ratio [OR], 0.92; 95% CI, 0.82-1.02). However, there was a lower rate of compartment syndrome/fasciotomy in the bilateral group (bilateral vs unilateral: OR, 0.80; 95% CI, 0.66-0.97). Bilateral cannulation was also associated with lower odds of cannulation site bleeding (bilateral vs unilateral: OR, 0.87; 95% CI, 0.76-0.99), vessel repair (bilateral vs unilateral: OR, 0.55; 95% CI, 0.38-0.79), and in-hospital mortality (bilateral vs unilateral: OR, 0.85; 95% CI, 0.81-0.91) compared with unilateral cannulation. These findings were unchanged after propensity matching.

CONCLUSIONS

This study showed no risk reduction for overall limb ischemia-related events requiring DPC after 6 hours when comparing bilateral to unilateral femoral cannulation in peripheral venoarterial ECMO. However, bilateral cannulation was associated with a reduced risk for compartment syndrome/fasciotomy, lower rates of bleeding and vessel repair during ECMO, and lower in-hospital mortality.

Adult Highlights From the Extracorporeal Life Support Organization Registry: 2017-2022

The Extracorporeal Life Support Organization (ELSO) registry captures clinical data and outcomes on patients receiving extracorporeal membrane oxygenation (ECMO) support across the globe at participating centers. It provides a very unique opportunity to benchmark outcomes and analyze the clinical course to help identify ways of improving patient outcomes. In this review, we summarize select adult ECMO articles published using the ELSO registry over the past 5 years. These articles highlight innovative utilization of the registry data in generating hypotheses for future clinical trials. Members of the ELSO Scientific Oversight Committee can be found here: https://www.elso.org/registry/socmembers.aspx .

Intracranial hemorrhage in a large cohort of patients supported with veno-venous ECMO. A retrospective single-center analysis

BACKGROUND

Intracranial bleeding (ICB) is a serious complication during veno-venous extracorporeal membrane oxygenation (V-V ECMO), with potentially fatal consequences.

PURPOSE

This study aimed to evaluate the incidence, time of detection of ICB among patients treated with V-V ECMO and potential risk factors for developing ICB during V-V ECMO.

METHODS

Five hundred fifty six patients were included in this retrospective single center analysis.

RESULTS

Median time on V-V ECMO was 9 (IQR 6-15) days. Intracranial bleeding during V-V ECMO was detected in 10.9% of all patients (61 patients with ICB). Only 17 patients with ICB presented obvious clinical symptoms. Intracranial bleeding was detected on cerebral imaging in median after 5 days (IQR 1-14) after starting V-V ECMO. Overall survival to hospital discharge was 63.7% (ICB: 29.5%). Risk factors of ICB before starting V-V ECMO in univariable analysis were platelets <100/nl (OR: 3.82), creatinine >1.5mg/dl (OR: 1.98), norepinephrine >2.5mg/h (OR: 2.5), ASAT >80U/L (OR: 1.86), blood-urea >100mg/dl (OR: 1.81) and LDH >550u/L (OR: 2.07). Factors associated with cannulation were rapid decrease in paCO2 >35mmHg (OR: 2.56) and rapid decrease in norepinephrine >1mg/h (OR: 2.53). Multivariable analysis revealed low platelets, high paCO2 before ECMO, and rapid drop in paCO2 after V-V ECMO initiation as significant risk factors for ICB.

CONCLUSION

The results emphasize that ICB is a frequent complication during V-V ECMO. Many bleedings were incidental findings, therefore screening for ICB is advisable. The univariate risk factors reflect the underlying disease severity, coagulation disorders and peri-cannulation factors, and may help to identify patients at risk.

Piloting an ICU follow-up clinic to improve health-related quality of life in ICU survivors after a prolonged intensive care stay (PINA): feasibility of a pragmatic randomised controlled trial

BACKGROUND

ICU survivors often suffer from prolonged physical and mental impairments resulting in the so called "Post-Intensive Care Syndrome" (PICS). The aftercare of former ICU patients affected by PICS in particular has not been addressed sufficiently in Germany so far. The aim of this study was to evaluate the feasibility of a pragmatic randomised trial (RCT) comparing an intensive care unit (ICU) follow-up clinic intervention to usual care.

METHODS

This pilot study in a German university hospital evaluated the feasibility of a pragmatic RCT. Patients were assigned in a 1:1 ratio to an ICU follow-up clinic intervention or to usual care. The concept of this follow-up clinic was previously developed in a participatory process with patients, next of kin, health care professionals and researchers. We performed a process evaluation and determined acceptability, fidelity, completeness of measurement instruments and practicality as feasibility outcomes. The RCT's primary outcome (health-related quality of life) was assessed six months after ICU discharge by means of the physical component scale of the Short-Form-12 self-report questionnaire.

RESULTS

The pilot study was conducted from June 2020 to May 2021 with 21 and 20 participants in the intervention and control group. Principal findings related to feasibility were 85% consent rate (N = 48), 62% fidelity rate, 34% attrition rate (N = 41) and 77% completeness of outcome measurements. The primary effectiveness outcome (health-related quality of life) could be measured in 93% of participants who completed the study (N = 27). The majority of participants (85%) needed assistance with follow-up questionnaires (practicality). Median length of ICU stay was 13 days and 85% (N = 41) received mechanical ventilation, median Sequential Organ Failure Assessment Score was nine. Six-month follow-up assessment was planned for all study participants and performed for 66% (N = 41) of the participants after 197 days (median).

CONCLUSION

The participatory developed intervention of an ICU follow-up clinic and the pragmatic pilot RCT both seem to be feasible. We recommend to start a pragmatic RCT on the effectiveness of the ICU follow-up clinic.

TRIAL REGISTRATION

ClinicalTrials.gov US NLM, NCT04186468, Submission: 02/12/2019, Registration: 04/12/2019, https://clinicaltrials.gov/ct2/show/NCT04186468.

The effects of nitric oxide on coagulation and inflammation in ex vivo models of extracorporeal membrane oxygenation and cardiopulmonary bypass

BACKGROUND

Extracorporeal life support (ECLS) has extensive applications in managing patients with acute cardiac and pulmonary failure. Two primary modalities of ECLS, cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO), include several similarities in their composition, complications, and patient outcomes. Both CPB and ECMO pose a high risk of thrombus formation and platelet activation due to the large surface area of the devices and bleeding due to system anticoagulation. Therefore, novel methods of anticoagulation are needed to reduce the morbidity and mortality associated with extracorporeal support. Nitric oxide (NO) has potent antiplatelet properties and presents a promising alternative or addition to anticoagulation with heparin during extracorporeal support.

METHODS

We developed two ex vivo models of CPB and ECMO to investigate NO effects on anticoagulation and inflammation in these systems.

RESULTS

Sole addition of NO as an anticoagulant was not successful in preventing thrombus formation in the ex vivo setups, therefore a combination of low-level heparin with NO was used. Antiplatelet effects were observed in the ex vivo ECMO model when NO was delivered at 80 ppm. Platelet count was preserved after 480 min when NO was delivered at 30 ppm.

CONCLUSION

Combined delivery of NO and heparin did not improve haemocompatibility in either ex vivo model of CPB and ECMO. Anti-inflammatory effects of NO in ECMO systems have to be evaluated further.

In-hospital and 6-month outcomes in patients with COVID-19 supported with extracorporeal membrane oxygenation (EuroECMO-COVID): a multicentre, prospective observational study

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been widely used in patients with COVID-19, but uncertainty remains about the determinants of in-hospital mortality and data on post-discharge outcomes are scarce. The aims of this study were to investigate the variables associated with in-hospital outcomes in patients who received ECMO during the first wave of COVID-19 and to describe the status of patients 6 months after ECMO initiation.

METHODS

EuroECMO-COVID is a prospective, multicentre, observational study developed by the European Extracorporeal Life Support Organization. This study was based on data from patients aged 16 years or older who received ECMO support for refractory COVID-19 during the first wave of the pandemic-from March 1 to Sept 13, 2020-at 133 centres in 21 countries. In-hospital mortality and mortality 6 months after ECMO initiation were the primary outcomes. Mixed-Cox proportional hazards models were used to investigate associations between patient and management-related variables (eg, patient demographics, comorbidities, pre-ECMO status, and ECMO characteristics and complications) and in-hospital deaths. Survival status at 6 months was established through patient contact or institutional charts review. This study is registered with ClinicalTrials.gov, NCT04366921, and is ongoing.

FINDINGS

Between March 1 and Sept 13, 2020, 1215 patients (942 [78%] men and 267 [22%] women; median age 53 years [IQR 46-60]) were included in the study. Median ECMO duration was 15 days (IQR 8-27). 602 (50%) of 1215 patients died in hospital, and 852 (74%) patients had at least one complication. Multiorgan failure was the leading cause of death (192 [36%] of 528 patients who died with available data). In mixed-Cox analyses, age of 60 years or older, use of inotropes and vasopressors before ECMO initiation, chronic renal failure, and time from intubation to ECMO initiation of 4 days or more were associated with higher in-hospital mortality. 613 patients did not die in hospital, and 547 (95%) of 577 patients for whom data were available were alive at 6 months. 102 (24%) of 431 patients had returned to full-time work at 6 months, and 57 (13%) of 428 patients had returned to part-time work. At 6 months, respiratory rehabilitation was required in 88 (17%) of 522 patients with available data, and the most common residual symptoms included dyspnoea (185 [35%] of 523 patients) and cardiac (52 [10%] of 514 patients) or neurocognitive (66 [13%] of 512 patients) symptoms.

INTERPRETATION

Patient's age, timing of cannulation (<4 days vs ≥4 days from intubation), and use of inotropes and vasopressors are essential factors to consider when analysing the outcomes of patients receiving ECMO for COVID-19. Despite post-discharge survival being favourable, persisting long-term symptoms suggest that dedicated post-ECMO follow-up programmes are required.

FUNDING

None.

Recirculation in single lumen cannula venovenous extracorporeal membrane oxygenation: A non-randomized bi-centric trial

Background

Recirculation is a common problem in venovenous (VV) extracorporeal membrane oxygenation (ECMO). The aims of this study were to compare recirculation fraction (Rf) between femoro-jugular and jugulo-femoral VV ECMO configurations, to identify risk factors for recirculation and to assess the impact on hemolysis.

Methods

Patients in the medical intensive care unit (ICU) at the University Medical Center Regensburg, Germany receiving VV ECMO with femoro-jugular, and jugulo-femoral configuration at the ECMO Center Karolinska, Sweden, were included in this non-randomized prospective study. Total ECMO flow (QEC), recirculated flow (QREC), and recirculation fraction Rf = QREC/QEC were determined using ultrasound dilution technology. Effective ECMO flow (QEFF) was defined as QEFF = QEC * (1–Rf). Demographics, cannula specifics, and markers of hemolysis were assessed. Survival was evaluated at discharge from ICU.

Results

Thirty-seven patients with femoro-jugular configuration underwent 595 single-point measurements and 18 patients with jugulo-femoral configuration 231 measurements. Rf was lower with femoro-jugular compared to jugulo-femoral configuration [5 (0, 11) vs. 19 (13, 28) %, respectively (p &lt; 0.001)], resulting in similar QEFF [2.80 (2.21, 3.39) vs. 2.79 (2.39, 3.08) L/min (p = 0.225)] despite lower QEC with femoro-jugular configuration compared to jugulo-femoral [3.01 (2.40, 3.70) vs. 3.57 (3.05, 4.06) L/min, respectively (p &lt; 0.001)]. In multivariate regression analysis, the type of configuration, distance between the two cannula tips, ECMO flow, and heart rate were significantly associated with Rf [B (95% CI): 25.8 (17.6, 33.8), p &lt; 0.001; 960.4 (960.7, 960.1), p = 0.009; 4.2 (2.5, 5.9), p &lt; 0.001; 960.1 (960.2, 0.0), p = 0.027]. Hemolysis was similar in subjects with Rf &gt; 8 vs. ≤ 8%. Explorative data on survival showed comparable results in the femoro-jugular and the jugulo-femoral group (81 vs. 72%, p = 0.455).

Conclusion

VV ECMO with femoro-jugular configuration caused less recirculation. Further risk factors for higher Rf were shorter distance between the two cannula tips, higher ECMO flow, and lower heart rate. Rf did not affect hemolysis.

Randomized Clinical Study of Temporary Transvenous Phrenic Nerve Stimulation in Difficult-to-Wean Patients

Rationale: Diaphragm dysfunction is frequently observed in critically ill patients with difficult weaning from mechanical ventilation. Objectives: To evaluate the effects of temporary transvenous diaphragm neurostimulation on weaning outcome and maximal inspiratory pressure. Methods: Multicenter, open-label, randomized, controlled study. Patients aged ⩾18 years on invasive mechanical ventilation for ⩾4 days and having failed at least two weaning attempts received temporary transvenous diaphragm neurostimulation using a multielectrode stimulating central venous catheter (bilateral phrenic stimulation) and standard of care (treatment) (n = 57) or standard of care (control) (n = 55). In seven patients, the catheter could not be inserted, and in seven others, pacing therapy could not be delivered; consequently, data were available for 43 patients. The primary outcome was the proportion of patients successfully weaned. Other endpoints were mechanical ventilation duration, 30-day survival, maximal inspiratory pressure, diaphragm-thickening fraction, adverse events, and stimulation-related pain. Measurements and Main Results: The incidences of successful weaning were 82% (treatment) and 74% (control) (absolute difference [95% confidence interval (CI)], 7% [-10 to 25]), P = 0.59. Mechanical ventilation duration (mean ± SD) was 12.7 ± 9.9 days and 14.1 ± 10.8 days, respectively, P = 0.50; maximal inspiratory pressure increased by 16.6 cm H₂O and 4.8 cm H₂O, respectively (difference [95% CI], 11.8 [5 to 19]), P = 0.001; and right hemidiaphragm thickening fraction during unassisted spontaneous breathing was +17% and -14%, respectively, P = 0.006, without correlation with changes in maximal inspiratory pressure. Serious adverse event frequency was similar in both groups. Median stimulation-related pain in the treatment group was 0 (no pain). Conclusions: Temporary transvenous diaphragm neurostimulation did not increase the proportion of successful weaning from mechanical ventilation. It was associated with a significant increase in maximal inspiratory pressure, suggesting reversal of the course of diaphragm dysfunction. Clinical trial registered with www.clinicaltrials.gov (NCT03096639) and the European Database on Medical Devices (CIV-17-06-020004).

Extracorporeal membrane oxygenation during pregnancy and peripartal. An international retrospective multicenter study

INTRODUCTION

Extracorporeal Membrane Oxygenation (ECMO) may be used in the setting of pregnancy or the peripartal period, however its utility has not been well-characterized. This study aims to give an overview on the prevalence of peripartel ECMO cases and further assess the indications and outcomes of ECMO in this setting across multiple centers and countries.

METHODS

A retrospective, multicenter, international cohort study of pregnant and peripartum ECMO cases was performed. Data were collected from six ECMO centers across three continents over a 10-year period.

RESULTS

A total of 60 pregnany/peripartal ECMO cases have been identified. Most frequent indications are acute respiratory distress syndrome (n = 30) and pulmonary embolism (n = 5). Veno-venous ECMO mode was applied more often (77%). ECMO treatment during pregnancy was performed in 17 cases. Maternal and fetal survival was high with 87% (n = 52), respectively 73% (n = 44).

CONCLUSIONS

Various emergency scenarios during pregnancy and at time of delivery may require ECMO treatment. Peripartal mortality in a well-resourced setting is rare, however emergencies in the labor room occur and knowledge of available rescue therapy is essential to improve outcome. Obstetricians and obstetric anesthesiologists should be aware of the availability of ECMO resource at their hospital or region to ensure immediate contact when needed.

Carbon Dioxide Elimination During Veno-Venous Extracorporeal Membrane Oxygenation Weaning: A Pilot Study

Veno-venous extracorporeal membrane oxygenation (V-V ECMO) represents a component of the treatment strategy for severe respiratory failure. Clinical evidence on the management of the lung during V-V ECMO are limited just as the consensus regarding timing of weaning. The monitoring of the carbon dioxide (CO2) removal (V'CO2TOT) is subdivided into two components: the membrane lung (ML) and the native lung (NL) are both taken into consideration to evaluate the improvement of the function of the lung and to predict the time to wean off ECMO. We enrolled patients with acute respiratory distress syndrome (ARDS). The V'CO2NL ratio (V'CO2NL/V'CO2TOT) value was calculated based on the distribution of CO2 between the NL and the ML. Of 18 patients, 15 were successfully weaned off of V-V ECMO. In this subgroup, we observed a significant increase in the V'CO2NL ratio comparing the median values of the first and last quartiles (0.32 vs. 0.53, p = 0.0045), without observing any modifications in the ventilation parameters. An increase in the V'CO2NL ratio, independently from any change in ventilation could, despite the limitations of the study, indicate an improvement in pulmonary function and may be used as a weaning index for ECMO.

Argatroban versus heparin in patients without heparin-induced thrombocytopenia during venovenous extracorporeal membrane oxygenation: a propensity-score matched study

BACKGROUND

During venovenous extracorporeal membrane oxygenation (vvECMO), direct thrombin inhibitors are considered by some potentially advantageous over unfractionated heparin (UFH). We tested the hypothesis that Argatroban is non-inferior to UFH regarding thrombosis and bleeding during vvECMO.

METHODS

We conducted a propensity-score matched observational non-inferiority study of consecutive patients without heparin-induced-thrombocytopenia (HIT) on vvECMO, treated between January 2006 and March 2019 in the medical intensive care unit at the University Hospital Regensburg. Anticoagulation was realized with UFH until August 2017 and with Argatroban from September 2017 onwards. Target activated partial thromboplastin time was 50 ± 5seconds in both groups. Primary composite endpoint was major thrombosis and/or major bleeding. Major bleeding was defined as a drop in hemoglobin of ≥ 2 g/dl/day or in transfusion of ≥ 2 packed red cells/24 h, or retroperitoneal, cerebral, or pulmonary bleeding. Major thrombosis was defined as obstruction of > 50% of the vessel lumen diameter by means of duplex sonography. We also assessed technical complications such as oxygenator defects or pump head thrombosis, the time-course of platelets, and the cost of anticoagulation (including HIT-testing).

RESULTS

Out of 465 patients receiving UFH, 78 were matched to 39 patients receiving Argatroban. The primary endpoint occurred in 79% of patients in the Argatroban group and in 83% in the UFH group (non-inferiority for Argatroban, p = 0.026). The occurrence of technical complications was equally distributed (Argatroban 49% vs. UFH 42%, p = 0.511). The number of platelets was similar in both groups before ECMO therapy but lower in the UFH group after end of ECMO support (median [IQR]: 141 [104;198]/nl vs. 107 [54;171]/nl, p = 0.010). Anticoagulation costs per day of ECMO were higher in the Argatroban group (€26 [13.8;53.0] vs. €0.9 [0.5;1.5], p < 0.001) but not after accounting for blood products and HIT-testing (€63 [42;171) vs. €40 [17;158], p = 0.074).

CONCLUSION

In patients without HIT on vvECMO, Argatroban was non-inferior to UFH regarding bleeding and thrombosis. The occurrence of technical complications was similarly distributed. Argatroban may have less impact on platelet decrease during ECMO, but this finding needs further evaluation. Direct drug costs were higher for Argatroban but comparable to UFH after accounting for HIT-testing and transfusions.

Piloting an ICU follow-up clinic to improve health-related quality of life in ICU survivors after a prolonged intensive care stay (PINA): study protocol for a pilot randomised controlled trial

Background

Intensive care unit (ICU) survivors often suffer from cognitive, physical and mental impairments, known as post-intensive care syndrome (PICS). ICU follow-up clinics may improve aftercare of these patients. There is a lack of evidence whether or which concept of an ICU follow-up clinic is effective. Within the PINA study, a concept for an ICU follow-up clinic was developed and will be tested in a pilot randomised controlled trial (RCT), primarily to evaluate the feasibility and additionally the potential efficacy.

Methods/design

Design: Pilot RCT with intervention and control (usual care) arms plus mixed-methods process evaluation. Participants: 100 ICU patients (50 per arm) of three ICUs in a university hospital (Regensburg, Germany), ≥ 18 years with an ICU stay of > 5 days, a sequential organ failure assessment (SOFA) score > 5 during the ICU stay and a life expectancy of more than 6 months.

Intervention: The intervention will contain three components: information, consultation and networking. Information will be available in form of an intensive care guide for patients and next of kin at the ICU and phone support during follow-up. For consultation, patients will visit the ICU follow-up clinic at least once during the first 6 months after discharge from ICU. During these visits, patients will be screened for symptoms of PICS and, if required, referred to specialists for further treatment. The networking part (e.g. special referral letter from the ICU follow-up clinic) aims to provide a network of outpatient care providers for former ICU patients. Feasibility Outcomes: Qualitative and quantitative evaluation will be used to explore reasons for non-participation and the intervention´s acceptability to patients and caregivers. Efficacy Outcomes: Health-related quality of life (HRQOL) will be assessed as primary outcome by the physical component score (PCS) of the Short-Form 12 Questionnaire (SF-12). Secondary outcomes encompass further patient-reported outcomes. All outcomes are assessed at 6 months after discharge from ICU.

Discussion

The PINA study will determine feasibility and potential efficacy of a complex intervention in a pilot RCT to enhance follow-up care of ICU survivors. The pilot study is an important step for further studies in the field of ICU aftercare and especially for the implementation of a pragmatic multi-centre RCT.

Trial registration

ClinicalTrials.gov, NCT04186468. Submitted 2 December 2019

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-021-00796-1.

The effect of hyperoxia on inflammation and platelet responses in an ex vivo extracorporeal membrane oxygenation circuit

Use of extracorporeal membrane oxygenation (ECMO) is expanding, however, it is still associated with significant morbidity and mortality. Activation of inflammatory and innate immune responses and hemostatic alterations contribute to complications. Hyperoxia may play a role in exacerbating these responses. Nine ex vivo ECMO circuits were tested using fresh healthy human whole blood, with two oxygen levels: 21% inspired fraction of oxygen (FiO₂ ; mild hyperoxia; n = 5) and 100% FiO₂ (severe hyperoxia; n = 4). Serial blood samples were taken for analysis of platelet aggregometry, leukocyte activation, inflammatory, and oxidative stress markers. ECMO resulted in reduced adenosine diphosphate- (P < .05) and thrombin receptor activating peptide-induced (P < .05) platelet aggregation, as well as increasing levels of the neutrophil activation marker, neutrophil elastase (P = .013). Additionally, levels of the inflammatory chemokine interleukin-8 were elevated (P < .05) and the activity of superoxide dismutase, a marker of oxidative stress, was increased (P = .002). Hyperoxia did not augment these responses, with no significant differences detected between mild and severe hyperoxia. Our ex vivo model of ECMO revealed that the circuit itself triggers a pro-inflammatory and oxidative stress response, however, exposure to supra-physiologic oxygen does not amplify that response. Extended-duration studies and inclusion of an endothelial component could be beneficial in characterizing longer term changes.

Pressure and flow properties of dual-lumen cannulae for extracorporeal membrane oxygenation

INTRODUCTION

In the last decade, dual-lumen cannulae have been increasingly applied in patients undergoing extracorporeal life support. Well-performing vascular access is crucial for efficient extracorporeal membrane oxygenation support; thus, guidance for proper cannulae size is required. Pressure-flow charts provided by manufacturers are often based on tests performed using water, rarely blood. However, blood is a shear-thinning and viscoelastic fluid characterized by different flow properties than water.

METHODS

We performed a study evaluating pressure-flow curves during standardized conditions using human whole blood in two commonly available dual-lumen cannulae used in neonates, pediatric, and adult patients. Results were merged and compared with the manufacturer's corresponding curves obtained from the public domain.

RESULTS

The results showed that using blood as compared with water predominantly influenced drainage flow. A 10-80% higher pressure-drop was needed to obtain same drainage flow (hematocrit of 26%) compared with manufacturer's water charts in 13-31 Fr bi-caval dual-lumen cannulae. The same net difference was found in cavo-atrial cannulae (16-32 Fr), where a lower drainage pressure was required (Hct of 26%) compared with the manufacturer's test using blood with an Hct of 33%. Return pressure-flow data were similar, independent whether pumping blood or water, to the data reported by manufacturers.

CONCLUSION

Non-standardized testing of pressure-flow properties of extracorporeal membrane oxygenation dual-lumen cannulae prevents an adequate prediction of pressure-flow results when these cannulae are used in patients. Properties of dual-lumen cannulae may vary between sizes within same cannula family, in particular concerning the drainage flow.

Long-term pulmonary function and quality of life in adults after extracorporeal membrane oxygenation for respiratory failure

BACKGROUND

There is a significant long-term burden on survivors after acute respiratory distress syndrome, even 5 years after discharge. This is not well investigated in patients treated with extracorporeal membrane oxygenation. The objective of this study was to describe very-long-term (⩾3 years) disability in lung function and morphology, quality of life, mood disorders, walking capacity, and return to work status in extracorporeal membrane oxygenation survivors.

METHODS

Single-center retrospective cohort study on long-term survivors treated with extracorporeal membrane oxygenation for respiratory failure between 1995 and 2010 at a tertiary referral center in Sweden. Eligible patients were approached, and those who consented were interviewed and investigated during a day at the hospital.

RESULTS

A total of 38 patients were investigated with a median follow-up time of 9.0 years. Quality of life was reduced in several Short form 36 (SF-36) subscales and all domains of the St George's Respiratory Questionnaire, similar to previous studies in conventionally managed acute respiratory distress syndrome survivors. A reduced diffusion capacity of carbon monoxide was seen in 47% of patients, and some degree of residual lung parenchymal pathology was seen in 82%. Parenchymal pathology correlated with reductions in quality of life and diffusion capacity. Symptoms of anxiety and depression were seen in 22% and 14%, respectively.

CONCLUSION

A significant long-term burden remains even 3-17 years after extracorporeal membrane oxygenation treatment, similar to conventionally managed acute respiratory distress syndrome survivors. Future prospective studies are needed to elucidate risk factors for these sequelae.

Pressure and flow properties of cannulae for extracorporeal membrane oxygenation I: return (arterial) cannulae

Adequate extracorporeal membrane oxygenation support in the adult requires cannulae permitting blood flows up to 6-8 L/minute. In accordance with Poiseuille's law, flow is proportional to the fourth power of cannula inner diameter and inversely proportional to its length. Poiseuille's law can be applied to obtain the pressure drop of an incompressible, Newtonian fluid (such as water) flowing in a cylindrical tube. However, as blood is a pseudoplastic non-Newtonian fluid, the validity of Poiseuille's law is questionable for prediction of cannula properties in clinical practice. Pressure-flow charts with non-Newtonian fluids, such as blood, are typically not provided by the manufacturers. A standardized laboratory test of return (arterial) cannulae for extracorporeal membrane oxygenation was performed. The aim was to determine pressure-flow data with human whole blood in addition to manufacturers' water tests to facilitate an appropriate choice of cannula for the desired flow range. In total, 14 cannulae from three manufacturers were tested. Data concerning design, characteristics, and performance were graphically presented for each tested cannula. Measured blood flows were in most cases 3-21% lower than those provided by manufacturers. This was most pronounced in the narrow cannulae (15-17 Fr) where the reduction ranged from 27% to 40% at low flows and 5-15% in the upper flow range. These differences were less apparent with increasing cannula diameter. There was a marked disparity between manufacturers. Based on the measured results, testing of cannulae including whole blood flows in a standardized bench test would be recommended.

The Extracorporeal Life Support Organization Maastricht Treaty for Nomenclature in Extracorporeal Life Support. A Position Paper of the Extracorporeal Life Support Organization

Extracorporeal life support (ECLS) was developed more than 50 years ago, initially with venoarterial and subsequently with venovenous configurations. As the technique of ECLS significantly improved and newer skills developed, complexity in terminology and advances in cannula design led to some misunderstanding of and inconsistency in definitions, both in clinical practice and in scientific research. This document is a consensus of multispecialty international representatives of the Extracorporeal Life Support Organization, including the North America, Latin America, EuroELSO, South West Asia and Africa, and Asia-Pacific chapters, imparting a global perspective on ECLS. The goal is to provide a consistent and unambiguous nomenclature for ECLS and to overcome the inconsistent use of abbreviations for ECLS cannulation. Secondary benefits are ease of multicenter collaboration in research, improved registry data quality, and clear communication among practitioners and researchers in the field.

Extracorporeal membrane oxygenation (ECMO) and the acute respiratory distress syndrome (ARDS): a systematic review of pre-clinical models

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) is an increasingly accepted means of supporting those with severe acute respiratory distress syndrome (ARDS). Given the high mortality associated with ARDS, numerous animal models have been developed to support translational research. Where ARDS is combined with ECMO, models are less well characterized. Therefore, we conducted a systematic literature review of animal models combining features of experimental ARDS with ECMO to better understand this situation.

DATA SOURCES

MEDLINE and Embase were searched between January 1996 and December 2018.

STUDY SELECTION

Inclusion criteria: animal models combining features of experimental ARDS with ECMO.

EXCLUSION CRITERIA

clinical studies, abstracts, studies in which the model of ARDS and ECMO has been reported previously, and studies not employing veno-venous, veno-arterial, or central ECMO.

DATA EXTRACTION

Data were extracted to fully characterize models. Variables related to four key features: (1) study design, (2) animals and their peri-experimental care, (3) models of ARDS and mechanical ventilation, and (4) ECMO and its intra-experimental management.

DATA SYNTHESIS

Seventeen models of ARDS and ECMO were identified. Twelve were published after 2009. All were performed in large animals, the majority (n = 10) in pigs. The median number of animals included in each study was 17 (12-24), with a median study duration of 8 h (5-24). Oleic acid infusion was the commonest means of inducing ARDS. Most models employed peripheral veno-venous ECMO (n = 12). The reporting of supportive measures and the practice of mechanical ventilation were highly variable. Descriptions of ECMO equipment and its management were more complete.

CONCLUSION

A limited number of models combine the features of experimental ARDS with ECMO. Among those that do, there is significant heterogeneity in both design and reporting. There is a need to standardize the reporting of pre-clinical studies in this area and to develop best practice in their design.

A narrative review of the technical standards for extracorporeal life support devices (pumps and oxygenators) in Europe

This review summarizes the European rules to control the market when introducing new products. In particular, it shows all the steps to achieve the European Conformity (CE Mark), a certification that all new medical products must achieve before being used in Europe. Extracorporeal membrane oxygenation (ECMO) devices are exposed to the same procedures. Hereby, we present some regulatory issues regarding pumps and oxygenators, providing technical details as released by the manufacturers on their websites and information charts.

Weaning from veno-venous extracorporeal membrane oxygenation: how I do it

Veno-venous extracorporeal membrane oxygenation (VV ECMO) is a rescue treatment for acute respiratory distress syndrome (ARDS) failing protective mechanical ventilation. It temporarily provides proper gas exchange: hypoxia is treated by adjusting the blood flow rate and fraction in spired oxygen over the ventilator (FiO2) on the extracorporeal membrane oxygenation (ECMO) circuit while CO2 removal is regulated by the ECMO fresh gas flow. Therefore, ventilator settings can be gradually reduced allowing the lungs to rest and recover. Nowadays, indications for ECMO referral and implantation are clearly formulated; on the contrary, little evidence currently exists to guide the process of weaning from ECMO support, especially concerning the timing during the course of lung healing. Therefore, indications to stop ECMO are less well standardized so that in clinical trials extracorporeal assistance is generally continued until lung recovery, with neither specific nor homogenous criteria for withdrawal. Notably, in almost all papers dealing with data on VV ECMO support, the management of weaning and the weaning procedure itself are not described. The aim of this paper is to make a picture of VV ECMO weaning, as it is performed in three European large volume intensive care units (ICUs) which represent referral centers for VV ECMO treatment. We focused on data concerning the timing of VV ECMO weaning and parameters at the time of weaning, in order to assess adequacy and safety of VV ECMO removal.

The impact of venovenous extracorporeal membrane oxygenation on cytokine levels in patients with severe acute respiratory distress syndrome: a prospective, observational study

OBJECTIVE

The immunoinflammatory response is central to the pathogenesis of acute respiratory distress syndrome (ARDS). However, little is known how this is affected by venovenous (VV) extracorporeal membrane oxygenation (ECMO). Our objective was to investigate the factors that influence the inflammatory response of patients with ARDS undergoing VV ECMO, and to analyse the impact of this response on hospital mortality.

DESIGN AND SETTING

A prospective observational study of all consecutive patients with severe ARDS who had VV ECMO at a tertiary German ECMO centre from 2009 to 2015. Patients without complete datasets were excluded. Cytokines (interleukin [IL]6, IL8 and tissue necrosis factor [TNF]_α) and inflammatory markers (white cell count and C-reactive protein) were assessed before ECMO initiation and on Days 1, 5 and 10, before explantation and at explantation.

RESULTS

A total of 262 adult patients undergoing VV ECMO were analysed. Their median Sequential Organ Failure Assessment score was 12, PaO₂/FiO₂ ratio was 64 mmHg, and overall in-hospital mortality was 34%. Cytokine levels fell quickly within 24 hours and fell further over the first 5 days. Extra-pulmonary ARDS was associated with higher IL6 and IL8 levels compared with pulmonary ARDS. Mechanical ventilation with positive end-expiratory pressure ≥ 15 cmH₂O before ECMO was associated with higher IL6, IL8 and TNF_α levels. Driving pressures ≥ 19 cmH₂O before ECMO were associated with higher IL8 levels. Non-survivors had higher IL6 and IL8 levels for the duration of ECMO.

CONCLUSION

Cytokine levels, on average, fall rapidly after initiation of VV ECMO, which may be related to the reduction of invasiveness of mechanical ventilation. Higher cytokine levels are associated with extrapulmonary causes of ARDS, more aggressive mechanical ventilation before VV ECMO, and mortality.

Acquired von Willebrand syndrome in respiratory extracorporeal life support: a systematic review of the literature

BACKGROUND AND OBJECTIVE

Venovenous extracorporeal membrane oxygenation (VV ECMO) and extracorporeal CO2 removal (ECCO2R) are increasingly used in the management of severe respiratory failure. With bleeding complications being one of the major risks of these techniques, our aim in this systematic review was to assess the available literature on acquired von Willebrand syndrome (AvWS) and extracorporeal support. AvWS has previously been associated with bleeding and shear stress.

DESIGN AND DATA SOURCES

A systematic review, using Medline via PubMed, was performed to identify eligible studies up to January 2017.

RESULTS AND CONCLUSION

The prevalence of AvWF among patients on VV ECMO or ECCO2R is high, but only a limited number of studies are reported in the literature. AvWS testing should be performed, including vWF multimer analysis, vWF activity and vWF antigen concentration. The extent to which vWF contributes to bleeding during ECMO, or how much changes in ECMO management can influence high molecular weight vWF multimer levels, cannot be answered from the currently available evidence and there remains a need for future studies.

Management strategies in venovenous extracorporeal membrane oxygenation: a retrospective comparison from five European centres

OBJECTIVE

To investigate contemporary clinical practice in the management of venovenous (VV) extracorporeal membrane oxygenation (ECMO) in critically ill patients with bacterial pneumonia.

METHODS

In this multicentre retrospective study, 48 patients with severe respiratory failure due to bacterial pneumonia receiving VV ECMO therapy in five experienced European ECMO centres were included. Ventilator and ECMO settings were analysed.

RESULTS

Ventilator settings showed great variability between participating centres, particularly relating to positive end-expiratory pressure, peak inspiratory pressure and driving pressure. Different strategies in cannulation, ECMO setting and weaning procedures were also observed.

CONCLUSION

There is great diversity in management modalities for ventilator and ECMO settings for patients with bacterial pneumonia. Our study emphasises the lack of clinical consensus in VV ECMO management.

Extracorporeal CO2 removal in critically ill patients: a systematic review

INTRODUCTION

The use of extracorporeal CO2 removal (ECCO2R) is increasingly employed in critically ill patients. However, the clinical evidence supporting its efficacy remains currently poor.

EVIDENCE ACQUISITION

A systematic review using MEDLINE via PubMed was performed to identify eligible studies (until 30th September 2016). The amount of CO2 reduction, the effect on the duration of mechanical ventilation and weaning, the impact on patients' outcome and the occurrence of complications were evaluated. The quality of evidence was evaluated according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) criteria.

EVIDENCE SYNTHESIS

Six studies were included (three evaluating patients with chronic obstructive pulmonary disease [COPD]; three evaluating patients with acute respiratory distress syndrome [ARDS]), involving 279 adult patients; 142 treated with ECCO2R and 137 controls. No study on pediatric population met the inclusion criteria for analysis. The overall quality of evidence of the two randomized trials and four case-control studies varied from moderate to very low. PaCO2 was generally reduced by 25-33% within a few hours following ECCO2R initiation. One ARDS study showed a significant decrease in the duration of mechanical ventilation, although this result was only found by post-hoc analysis. The three studies on COPD demonstrated that some patients supported by ECCO2R devices could avoid endotracheal intubation, however the ICU-LOS and survival was not influenced by ECCO2R when compared to controls.

CONCLUSIONS

In COPD patients, a significantly reduced need for endotracheal intubation was reported. However, the use of ECCO2R has not shown significant improvement on the outcome of critically ill patients in the reviewed studies. Therefore appropriately powered, randomized, controlled studies are urgently needed.

A prospective longitudinal cohort study: evolution of GERD symptoms during the course of pregnancy

Background

Symptoms of gastro-esophageal reflux disease (GERD) in pregnancy are reported with a prevalence of 30–80%. The aim of this study was to assess the prevalence and severity of GERD symptoms during the course of pregnancy. Furthermore current practice in medical care for GERD during pregnancy was assessed.

Methods

We performed a prospective longitudinal cohort study on 510 pregnant women (mean age 28.12, SD 5.3). Investigations for reflux symptoms where based on the use of validated reflux-disease questionnaire (RDQ). Additional information was collected about the therapy. A group of non-pregnant women (mean age 24.56, SD 5.7) was included as controls. Frequency and severity of reflux symptoms were recorded in each trimester of pregnancy.

Results

The prevalence of GERD symptoms in pregnant women increased from the first trimester with 26.1 to 36.1% in the second trimester and to 51.2% in the third trimester of pregnancy. The prevalence of GERD symptoms in the control group was 9.3%.

Pregnant women received medication for their GERD symptoms in 12.8% during the first, 9.1% during the second and 15.7% during the third trimester. Medications used >90% antacids, 0% PPI.

Conclusion

GERD symptoms occur more often in pregnant women than in non-pregnant and the frequency rises in the course of pregnancy. Medical therapy is used in a minority of cases and often with no adequate symptom relief.

Helicobacter pylori infection and the respiratory system: a systematic review of the literature

BACKGROUND

Recent studies suggest an increased Helicobacter pylori prevalence in patients with various extradigestive inflammatory diseases. Similar to H. pylori infection, many respiratory diseases are characterized by chronic inflammation as well as increased immune response. Recent studies have evaluated the relation between various respiratory disorders and H. pylori infection. The aim of this systematic review was to scrutinize the relevant literature and the mechanisms that could underlie a role for H. pylori infection in respiratory diseases.

METHODS

Relevant literature regarding pathophysiological mechanisms and clinical epidemiology of H. pylori and different respiratory diseases has been systematically identified and analyzed by two independent reviewers according to a PubMed search for English language (until week 14, April 2010).

CONCLUSIONS

At present, there is no definite proof of a causal relationship between H. pylori and respiratory diseases. Both H. pylori and various respiratory diseases are characterized by the release of proinflammatory cytokines and attraction of granulocytes as well as B- and T-cell-mediated response, though a pathophysiological association has not been proven. Neither the role of genetic predisposition of the host nor the presence of virulence factors nor the impact of H. pylori eradication have been studied in detail and definitely need further evaluation.

[Bronchopulmonary manifestations of gastroesophageal reflux disease]

Gastroesophageal reflux disease (GERD) is a common disease in the western world. Usually it occurs with typical symptoms like heartburn and regurgitation, but almost every third GERD-patient presents with extraesophageal symptoms and diseases in which a causal relation with GERD is discussed. The extraesophageal symptoms possibly associated with GERD are chronic cough, bronchial asthma, sleep disturbances including obstructive sleep apnea, hoarseness, dental erosions, non-cardiac chest pain and idiopathic pulmonary fibrosis. This article gives an overview of the reflux-associated diseases of the airways as well as the proposed pathomechanisms and therapeutic options.

The elucidation of peptic esophagitis: from Hamperl to heartburn

Although the esophagus was initially considered as the "humble" organ, it has in recent times evoked both substantial interest and considerable controversy as esophagitis becomes a global pandemic and the debate over the causes of esophagitis and the management of Barrett's has escalated. The esophagus has always defied easy understanding and the origins of its name and its symptomatology continue to confound those who address them. Esophagitis is increasing relentlessly on a global scale and the challenge of defining its symptomatology remains today as great a problem as when initially identified by Herwig Hamperl and Asher Winkelstein. Their identification of the entity they called "peptic esophagitis" in 1934, while initially for the most part overlooked, has today become one of the centers of gastroenterological focus. Although the initial symptomatology of esophagitis was limited to heartburn, it has more recently become apparent that a diverse group of symptoms is produced by the inflammation associated with intermittent reflux of gastric acid. Of interest is the nature of the original observations that led to the identification of the physiopathology of esophagitis and the elucidation of the relationship between symptomatology, acid reflux and inflammation. Although Asher Winkelstein of New York has long been considered the first to define the relationship of acid peptic reflux, esophageal ulceration and reflux symptomatology, it is of note to consider the seminal role of Herwig Hamperl, an Austrian pathologist in the elucidation of acid peptic esophagitis. Indeed, a careful consideration of the relative contributions of these two pioneers suggests that both deserve credit for identifying a disease process that, although initially for the most part ignored by clinicians, has now become one of the most fundamental problems faced by both gastroenterologists and pathologists.