Determinants of Effect of Extracorporeal CO2 Removal in Hypoxemic Respiratory Failure

Extracorporeal CO2 removal in severe respiratory acidotic intubated patients: A seven year experience observational study

Severe hypercapnia increases the risk of non-protective ventilation and is associated with high mortality in critically ill patients. In this study we assess the use of low-flow extracorporeal CO2 removal (ECCO2R) integrated into a renal platform and the factors related to patient outcome in a tertiary university hospital. Data from 73 patients with severe respiratory acidosis (pCO2 > 60 mmHg and Ph < 7.25 for more than 3 h) at risk for ventilator-induced lung injury (VILI), were analysed. The median duration of the therapy was 96 h (IQR 58 to 163). We observed that early use of ECCO2R (within 6h from meeting treatment criteria) was associated with a significant reduction in mortality (54.5 vs 77.5 %, p = 0.038) and a non-significant reduction in the duration of ECCO2R therapy, mechanical ventilation days, ICU length of stay and need for tracheostomy. Adverse events were found in 7 % of the patients, with no cases of major bleeding. A significant shorter mean life was observed for larger membranes (1.8 m2) in respect to 0.35 and 0.8 m2. We conclude that ECCO2R integrated into renal platforms is a feasible and safe technique in severe respiratory acidosis when there is risk for VILI.

Effect of a driving pressure-limiting strategy for patients with acute respiratory distress syndrome secondary to community-acquired pneumonia: the STAMINA randomised clinical trial

BACKGROUND

This study aimed to assess whether a driving pressure-limiting strategy based on positive end-expiratory pressure (PEEP) titration according to best respiratory system compliance and tidal volume adjustment increases the number of ventilator-free days within 28 days in patients with moderate to severe acute respiratory distress syndrome (ARDS).

METHODS

This is a multi-centre, randomised trial, enrolling adults with moderate to severe ARDS secondary to community-acquired pneumonia. Patients were randomised to a driving pressure-limiting strategy or low PEEP strategy based on a PEEP:FiO2 table. All patients received volume assist-control mode until day 3 or when considered ready for spontaneous modes of ventilation. The primary outcome was ventilator-free days within 28 days. Secondary outcomes were in-hospital and intensive care unit mortality at 90 days.

RESULTS

The trial was stopped because of recruitment fatigue after 214 patients were randomised. In total, 198 patients (n=96 intervention group, n=102 control group) were available for analysis (median age 63 yr, [interquartile range 47-73 yr]; 36% were women). The mean difference in driving pressure up to day 3 between the intervention and control groups was -0.7 cm H2O (95% confidence interval -1.4 to -0.1 cm H2O). Mean ventilator-free days were 6 (sd 9) in the driving pressure-limiting strategy group and 7 (9) in the control group (proportional odds ratio 0.72, 95% confidence interval 0.39-1.32; P=0.28). There were no significant differences regarding secondary outcomes.

CONCLUSIONS

In patients with moderate to severe ARDS secondary to community-acquired pneumonia, a driving pressure-limiting strategy did not increase the number of ventilator-free days compared with a standard low PEEP strategy within 28 days.

CLINICAL TRIAL REGISTRATION

NCT04972318.

Potential clinical impact of predictive modeling of heterogeneous treatment effects: scoping review of the impact of the PATH Statement

Background

The PATH Statement (2020) proposed predictive modeling for examining heterogeneity in treatment effects (HTE) in randomized clinical trials (RCTs). It distinguished risk modeling, which develops a multivariable model predicting individual baseline risk of study outcomes and examines treatment effects across risk strata, from effect modeling, which directly estimates individual treatment effects from models that include treatment, multiple patient characteristics and interactions of treatment with selected characteristics.

Purpose

To identify, describe and evaluate findings from reports that cite the Statement and present predictive modeling of HTE in RCTs.

Data Extraction

We identified reports using PubMed, Google Scholar, Web of Science, SCOPUS through July 5, 2024. Using double review with adjudication, we assessed consistency with Statement recommendations, credibility of HTE findings (applying criteria adapted from the Instrument to assess Credibility of Effect Modification Analyses (ICEMAN)), and clinical importance of credible findings.

Results

We identified 65 reports (presenting 31 risk models, 41 effect models). Contrary to Statement recommendations, only 25 of 48 studies with positive overall findings included a risk model; most effect models included multiple predictors with little prior evidence for HTE. Claims of HTE were noted in 23 risk modeling and 31 effect modeling reports, but risk modeling met credibility criteria more frequently (87 vs 32 percent). For effect models, external validation of HTE findings was critical in establishing credibility. Credible HTE from either approach was usually judged clinically important (24 of 30). In 19 reports from trials suggesting overall treatment benefits, modeling identified subgroups of 5-67% of patients predicted to experience no benefit or net treatment harm. In five that found no overall benefit, subgroups of 25-60% of patients were nevertheless predicted to benefit.

Conclusions

Multivariable predictive modeling identified credible, clinically important HTE in one third of 65 reports. Risk modeling found credible HTE more frequently; effect modeling analyses were usually exploratory, but external validation served to increase credibility.

Blood Pressure Targets for Adults with Vasodilatory Shock - An Individual Patient Data Meta-Analysis

BACKGROUND

We sought to estimate whether a lower mean arterial blood pressure target, compared with a higher mean arterial blood pressure target, reduced 90-day all-cause mortality among critically ill adult patients with vasodilatory shock.

METHODS

We conducted an individual patient data meta-analysis of randomized controlled trials that evaluated the effect of distinct thresholds of mean arterial blood pressure to guide vasopressor support among critically ill adults identified in a systematic literature search. The main exposure was a lower mean arterial pressure target compared with a higher mean arterial pressure target (including usual care). The primary outcome was 90-day all-cause mortality. We used a Bayesian random effects log-binomial model to estimate risk ratios with 95% credible intervals (CrIs).

RESULTS

Between 2010 and 2019, 3352 patients were randomly assigned in three trials (SEPSISPAM, OVATION pilot trial, and 65-Trial) across 103 hospitals from the United Kingdom, France, and Canada. When compared with a higher mean arterial blood pressure target or usual care, the risk ratio for 90-day all-cause mortality associated with a lower blood pressure target was 0.93 (95% CrI, 0.76 to 1.07; low certainty, posterior probability of benefit 87%). Results were consistent across multiple secondary and sensitivity analyses, including adjustment for prognostically important baseline covariates and alternative modeling techniques. Multiple approaches to evaluate the heterogeneity of treatment effect did not identify any subgroups that may potentially benefit from higher mean arterial blood pressure targets.

CONCLUSIONS

Targeting a lower mean arterial blood pressure for vasopressor therapy in critically ill patients with vasodilatory shock possibly reduced 90-day all-cause mortality. However, the certainty of evidence is low, and this analysis does not exclude the possibility that lower targets may cause harm overall.

Feasibility and safety of ultra-low volume ventilation (≤ 3 ml/kg) combined with extra corporeal carbon dioxide removal (ECCO2R) in acute respiratory failure patients

BACKGROUND

Ultra-protective ventilation is the combination of low airway pressures and tidal volume (Vt) combined with extra corporeal carbon dioxide removal (ECCO2R). A recent large study showed no benefit of ultra-protective ventilation compared to standard ventilation in ARDS (Acute Respiratory Distress Syndrome) patients. However, the reduction in Vt failed to achieve the objective of less than or equal to 3 ml/kg predicted body weight (PBW). The main objective of our study was to assess the feasibility of the ultra-low volume ventilation (Vt ≤ 3 ml/kg PBW) facilitated by ECCO2R in acute respiratory failure patients.

METHODS

Retrospective analysis of a prospective cohort of patients with either high or low blood flow veno-venous ECCO2R devices. A session was defined as a treatment of ECCO2R from the start to the removal of the device (one patient could have one more than one session). Primary endpoint was the proportion of sessions during which a Vt less or equal to 3 ml/kg PBW at 24 h after the start of ECCO2R was successfully achieved for at least 12 h. Secondary endpoints were respiratory variables, rate of adverse events and outcomes.

RESULTS

Forty-five ECCO2R sessions were recorded among 41 patients. Ultra-low volume ventilation (tidal volume ≤ 3 ml/kg PBW, success group) was successfully achieved at 24 h in 40.0% sessions (18 out of 45 sessions, confidence interval 25.3-54.6%). At 24 h, tidal volume in the failure group was 4.1 [3.8-4.5] ml/kg PBW compared to 2.1 [1.9-2.5] in the success group (p < 0.001). After multivariate analysis, blood flow rate was significantly associated with success of ultra-low volume ventilation (adjusted OR per 100 ml/min increase 1.51 (95%CI 1.21-1.90, p = 0.0003).

CONCLUSION

Ultra-low volume ventilation (≤ 3 ml/kg PBW) was feasible in 18 out of 45 sessions. Higher blood flow rates were associated with the success of ultra-low volume ventilation.

Precision Medicine in Acute Respiratory Distress Syndrome: Progress, Challenges, and the Road ahead

Several novel high-dimensional biologic measurements are increasingly being applied to biomedical sciences. Acute respiratory distress syndrome (ARDS) is a theoretically fertile ground for such approaches. Not only are these biologic and analytic tools available to better understand ARDS but also arguably, simpler approaches such as respiratory physiology has been vastly underutilized as a means of delivering precision-based care in the field. Here we review the progress made in ARDS toward discovering biologically homogeneous phenotypes, treatment responsive subgroups, the challenges to implement these discoveries at the bedside, and the road ahead that will enable precision medicine in ARDS.

Expert perspectives on ECCO2R for acute hypoxemic respiratory failure: consensus of a 2022 European roundtable meeting

BACKGROUND

By controlling hypercapnia, respiratory acidosis, and associated consequences, extracorporeal CO2 removal (ECCO2R) has the potential to facilitate ultra-protective lung ventilation (UPLV) strategies and to decrease injury from mechanical ventilation. We convened a meeting of European intensivists and nephrologists and used a modified Delphi process to provide updated insights into the role of ECCO2R in acute respiratory distress syndrome (ARDS) and to identify recommendations for a future randomized controlled trial.

RESULTS

The group agreed that lung protective ventilation and UPLV should have distinct definitions, with UPLV primarily defined by a tidal volume (VT) of 4-6 mL/kg predicted body weight with a driving pressure (ΔP) ≤ 14-15 cmH2O. Fourteen (93%) participants agreed that ECCO2R would be needed in the majority of patients to implement UPLV. Furthermore, 10 participants (majority, 63%) would select patients with PaO2:FiO2 > 100 mmHg (> 13.3 kPa) and 14 (consensus, 88%) would select patients with a ventilatory ratio of > 2.5-3. A minimum CO2 removal rate of 80 mL/min delivered by continuous renal support machines was suggested (11/14 participants, 79%) for this objective, using a short, double-lumen catheter inserted into the right internal jugular vein as the preferred vascular access. Of the participants, 14/15 (93%, consensus) stated that a new randomized trial of ECCO2R is needed in patients with ARDS. A ΔP of ≥ 14-15 cmH2O was suggested by 12/14 participants (86%) as the primary inclusion criterion.

CONCLUSIONS

ECCO2R may facilitate UPLV with lower volume and pressures provided by the ventilator, while controlling respiratory acidosis. Since recent European Society of Intensive Care Medicine guidelines on ARDS recommended against the use of ECCO2R for the treatment of ARDS outside of randomized controlled trials, new trials of ECCO2R are urgently needed, with a ΔP of ≥ 14-15 cmH2O suggested as the primary inclusion criterion.

From ICU Syndromes to ICU Subphenotypes: Consensus Report and Recommendations for Developing Precision Medicine in the ICU

Critical care uses syndromic definitions to describe patient groups for clinical practice and research. There is growing recognition that a "precision medicine" approach is required and that integrated biologic and physiologic data identify reproducible subpopulations that may respond differently to treatment. This article reviews the current state of the field and considers how to successfully transition to a precision medicine approach. To impact clinical care, identification of subpopulations must do more than differentiate prognosis. It must differentiate response to treatment, ideally by defining subgroups with distinct functional or pathobiological mechanisms (endotypes). There are now multiple examples of reproducible subpopulations of sepsis, acute respiratory distress syndrome, and acute kidney or brain injury described using clinical, physiological, and/or biological data. Many of these subpopulations have demonstrated the potential to define differential treatment response, largely in retrospective studies, and that the same treatment-responsive subpopulations may cross multiple clinical syndromes (treatable traits). To bring about a change in clinical practice, a precision medicine approach must be evaluated in prospective clinical studies requiring novel adaptive trial designs. Several such studies are underway, but there are multiple challenges to be tackled. Such subpopulations must be readily identifiable and be applicable to all critically ill populations around the world. Subdividing clinical syndromes into subpopulations will require large patient numbers. Global collaboration of investigators, clinicians, industry, and patients over many years will therefore be required to transition to a precision medicine approach and ultimately realize treatment advances seen in other medical fields.

Extracorporeal Carbon Dioxide Removal to Avoid Invasive Ventilation During Exacerbations of Chronic Obstructive Pulmonary Disease: VENT-AVOID Trial - A Randomized Clinical Trial

Rationale: It is unclear whether extracorporeal CO2 removal (ECCO2R) can reduce the rate of intubation or the total time on invasive mechanical ventilation (IMV) in adults experiencing an exacerbation of chronic obstructive pulmonary disease (COPD). Objectives: To determine whether ECCO2R increases the number of ventilator-free days within the first 5 days postrandomization (VFD-5) in exacerbation of COPD in patients who are either failing noninvasive ventilation (NIV) or who are failing to wean from IMV. Methods: This randomized clinical trial was conducted in 41 U.S. institutions (2018-2022) (ClinicalTrials.gov ID: NCT03255057). Subjects were randomized to receive either standard care with venovenous ECCO2R (NIV stratum: n = 26; IMV stratum: n = 32) or standard care alone (NIV stratum: n = 22; IMV stratum: n = 33). Measurements and Main Results: The trial was stopped early because of slow enrollment and enrolled 113 subjects of the planned sample size of 180. There was no significant difference in the median VFD-5 between the arms controlled by strata (P = 0.36). In the NIV stratum, the median VFD-5 for both arms was 5 days (median shift = 0.0; 95% confidence interval [CI]: 0.0-0.0). In the IMV stratum, the median VFD-5 in the standard care and ECCO2R arms were 0.25 and 2 days, respectively; median shift = 0.00 (95% confidence interval: 0.00-1.25). In the NIV stratum, all-cause in-hospital mortality was significantly higher in the ECCO2R arm (22% vs. 0%, P = 0.02) with no difference in the IMV stratum (17% vs. 15%, P = 0.73). Conclusions: In subjects with exacerbation of COPD, the use of ECCO2R compared with standard care did not improve VFD-5. Clinical trial registered with www.clinicaltrials.gov (NCT03255057).

Ultraprotective Ventilation via ECCO2R in Three Patients Presenting an Air Leak: Is ECCO2R Effective?

Extracorporeal CO₂ removal (ECCO2R) is a therapeutic approach that allows protective ventilation in acute respiratory failure by preventing hypercapnia and subsequent acidosis. The main indications for ECCO2R in acute respiratory failure are COPD (chronic obstructive pulmonary disease) exacerbation, acute respiratory distress syndrome (ARDS) and other situations of asthmatics status. However, CO₂ removal procedure is not extended to those ARDS patients presenting an air leak. Here, we report three cases of air leaks in patients with an ARDS that were successfully treated using a new ECCO2R device. Case 1 is a polytrauma patient that developed pneumothorax during the hospital stay, case 2 is a patient with a post-surgical bronchial fistula after an Ivor-Lewis esophagectomy, and case 3 is a COVID-19 patient who developed a spontaneous pneumothorax after being hospitalized for a prolonged time. ECCO2R allowed for protective ventilation mitigating VILI (ventilation-induced lung injury) and significantly improved hypercapnia and respiratory acidemia, allowing time for the native lung to heal. Although further investigation is needed, our observations seem to suggest that CO₂ removal can be a safe and effective procedure in patients connected to mechanical ventilation with ARDS-associated air leaks.

Laying the Groundwork for Physiology-Guided Precision Medicine in the Critically Ill

Canonical critical care syndromes such as sepsis and acute respiratory distress syndrome (ARDS) include patients with markedly heterogeneous biology.1 This, paired with decades of randomized controlled trials (RCTs) that were traditionally viewed as "negative," has stalled progress in improving patient outcomes.2 However, emerging awareness of sub-phenotypes based on differences in biomarker profiles and resulting heterogeneous treatment effects have led to calls for precision medicine in which therapies are targeted to those most likely to benefit.3.