Ultraprotective ventilation allowed by extracorporeal CO2 removal improves the right ventricular function in acute respiratory distress syndrome patients: a quasi-experimental pilot study

Right Ventricular Injury Definition and Management in Veno-Venous Extracorporeal Membrane Oxygenation

Right ventricular injury (RVI) in respiratory failure receiving veno-venous extracorporeal membrane oxygenation (VV ECMO) is associated with significant mortality. A scoping review is necessary to map the current literature and guide future research regarding the definition and management of RVI in patients receiving VV ECMO. We searched for relevant publications on RVI in patients receiving VV ECMO in Medline, EMBASE, and Web of Science. Of 1,868 citations screened, 30 studies reported on RVI (inclusive of right ventricular dilation, right ventricular dysfunction, and right ventricular failure) during VV ECMO. Twenty-three studies reported on the definition of RVI including echocardiographic indices of RV function and dimensions, whereas 13 studies reported on the management of RVI, including veno-pulmonary (VP) ECMO, veno-arterial (VA) ECMO, positive inotropic agents, pulmonary vasodilators, ultra-lung-protective ventilation (Ultra-LPV), and optimization of positive end-expiratory pressure (PEEP). The definitions of RVI in patients receiving VV ECMO used in the literature are heterogeneous. Despite the high incidence of RVI during VV ECMO support and its strong association with mortality, studies investigating therapeutic strategies for RVI are also lacking. To fill the existing knowledge gaps, a consensus on the definition of RVI and research investigating RV-targeted therapies during VV ECMO is urgently warranted.

The Effect of Lower Tidal Volume Ventilation Facilitated by Extracorporeal Carbon Dioxide Removal Compared With Conventional Lung Protective Ventilation on Cardiac Function

OBJECTIVES

Lower tidal volume ventilation (targeting 3 mL/kg predicted body weight, PBW) facilitated by extracorporeal carbon dioxide removal (ECCO2R) has been investigated as a potential therapy for acute hypoxemic respiratory failure (AHRF) in the pRotective vEntilation with veno-venouS lung assisT in respiratory failure (REST) trial. We investigated the effect of this strategy on cardiac function, and in particular the right ventricle.

DESIGN

Substudy of the REST trial.

SETTING

Nine U.K. ICUs.

PATIENTS

Patients with AHRF (Pao2/Fio2 < 150 mm Hg [20 kPa]).

INTERVENTION

Transthoracic echocardiography and N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements were collected at baseline and postrandomization in patients randomized to ECCO2R or usual care.

MEASUREMENTS

The primary outcome measures were a difference in tricuspid annular plane systolic excursion (TAPSE) on postrandomization echocardiogram and difference in NT-proBNP postrandomization.

RESULTS

There were 21 patients included in the echocardiography cohort (ECCO2R, n = 13; usual care, n = 8). Patient characteristics were similar in both groups at baseline. Median (interquartile range) tidal volumes were lower in the ECCO2R group compared with the usual care group postrandomization; 3.6 (3.1-4.2) mL/kg PBW versus 5.2 (4.9-5.7) mL/kg PBW, respectively (p = 0.01). There was no difference in the primary outcome measure of mean (sd) TAPSE in the ECCO2R and usual care groups postrandomization; 21.3 (5.4) mm versus 20.1 (3.2) mm, respectively (p = 0.60). There were 75 patients included in the NT-proBNP cohort (ECCO2R, n = 36; usual care, n = 39). Patient characteristics were similar in both groups at baseline. Median (interquartile range [IQR]) tidal volumes were lower in the ECCO2R group than the usual care group postrandomization; 3.8 (3.3-4.2) mL/kg PBW versus 6.7 (5.8-8.1) mL/kg PBW, respectively (p < 0.0001). There was no difference in median (IQR) NT-proBNP postrandomization; 1121 (241-5370) pg/mL versus 1393 (723-4332) pg/mL in the ECCO2R and usual care groups, respectively (p = 0.30).

CONCLUSIONS

In patients with AHRF, a reduction in tidal volume facilitated by ECCO2R, did not modify cardiac function.

Right ventricle-specific therapies in acute respiratory distress syndrome: a scoping review

OBJECTIVE

To summarize knowledge and identify gaps in evidence regarding treatment of right ventricular dysfunction (RVD) in acute respiratory distress syndrome (ARDS).

DATA SOURCES

We conducted a comprehensive search of MEDLINE, Embase, CINAHL, Web of Science, and the Cochrane Central Register of Controlled Trials.

STUDY SELECTION

Studies were included if they reported effects of treatments on right ventricular function, whether or not the intent was to modify right ventricular function.

DATA EXTRACTION

Data extraction was performed independently and in duplicate by two authors. Data items included the study design, patient population, type of intervention, comparison group, and RV-specific outcomes.

DATA SYNTHESIS

Of 1,430 studies screened, 51 studies reporting on 1,526 patients were included. By frequency, the included studies examined the following interventions: ventilator settings (29.4%), inhaled medications (33.3%), extracorporeal life support (13.7%), intravenous or oral medications (13.7%), and prone positioning (9.8%). The majority of the studies were non-randomized experimental studies (53%), with the next most common being case reports (16%). Only 5.9% of studies were RCTs. In total, 27% of studies were conducted with the goal of modifying RV function.

CONCLUSIONS

Given the prevalence of RVD in ARDS and its association with mortality, the dearth of research on this topic is concerning. This review highlights the need for prospective trials aimed at treating RV dysfunction in ARDS.

Extracorporeal carbon dioxide removal in acute hypoxaemic respiratory failure: a systematic review, Bayesian meta-analysis and trial sequential analysis

PURPOSE

To assess the safety and efficacy of extracorporeal carbon dioxide removal (ECCO2R) versus standard care in patients with acute hypoxaemic respiratory failure (AHRF).

METHODS

MEDLINE, Embase and clinical trial registries were searched from 1994 to 31 December 2021. We included randomised controlled trials (RCTs) and observational studies. Pairs of reviewers independently extracted data and assessed the risk of bias. The primary outcome was mortality. Secondary outcomes included ventilator-free days, length of stay, safety and adverse events and physiological changes. As a primary analysis, we performed a meta-analysis of mortality until day 30 using a Bayesian random effects model. We then performed a trial sequential analysis of RCTs.

RESULTS

21 studies met inclusion criteria: three RCTs, enrolling 531 patients, and 18 observational studies. In a pooled analysis of RCTs, the posterior probability of increased mortality with the use of ECCO2R was 73% (relative risk 1.19, 95% credible interval 0.70-2.29). There was substantial heterogeneity in the reporting of safety and adverse events. However, the incidence of extra and intracranial haemorrhage was higher (relative risk 3.00, 95% credible interval 0.41-20.51) among those randomised to ECCO2R. Current trials have accumulated 80.8% of the diversity-adjusted required information size and the lack of effect reaches futility for a 10% absolute risk reduction in mortality.

CONCLUSIONS

The use of ECCO2R in patients with AHRF is not associated with improvements in clinical outcomes. Furthermore, it is likely that further trials of ECCO2R aiming to achieve an absolute risk reduction in mortality of ≥10% are futile.

Venovenous extracorporeal CO2 removal to support ultraprotective ventilation in moderate-severe acute respiratory distress syndrome: A systematic review and meta-analysis of the literature

BACKGROUND

A strategy that limits tidal volumes and inspiratory pressures, improves outcomes in patients with the acute respiratory distress syndrome (ARDS). Extracorporeal carbon dioxide removal (ECCO₂R) may facilitate ultra-protective ventilation. We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of venovenous ECCO₂R in supporting ultra-protective ventilation in moderate-to-severe ARDS.

METHODS

MEDLINE and EMBASE were interrogated for studies (2000-2021) reporting venovenous ECCO₂R use in patients with moderate-to-severe ARDS. Studies reporting ≥10 adult patients in English language journals were included. Ventilatory parameters after 24 h of initiating ECCO₂R, device characteristics, and safety outcomes were collected. The primary outcome measure was the change in driving pressure at 24 h of ECCO₂R therapy in relation to baseline. Secondary outcomes included change in tidal volume, gas exchange, and safety data.

RESULTS

Ten studies reporting 421 patients (PaO₂:FiO₂ 141.03 mmHg) were included. Extracorporeal blood flow rates ranged from 0.35-1.5 L/min. Random effects modelling indicated a 3.56 cmH₂O reduction (95%-CI: 3.22-3.91) in driving pressure from baseline (p < .001) and a 1.89 mL/kg (95%-CI: 1.75-2.02, p < .001) reduction in tidal volume. Oxygenation, respiratory rate and PEEP remained unchanged. No significant interactions between driving pressure reduction and baseline driving pressure, partial pressure of arterial carbon dioxide or PaO₂:FiO₂ ratio were identified in metaregression analysis. Bleeding and haemolysis were the commonest complications of therapy.

CONCLUSIONS

Venovenous ECCO₂R permitted significant reductions in ∆P in patients with moderate-to-severe ARDS. Heterogeneity amongst studies and devices, a paucity of randomised controlled trials, and variable safety reporting calls for standardisation of outcome reporting. Prospective evaluation of optimal device operation and anticoagulation in high quality studies is required before further recommendations can be made.

Relationship between echocardiographic tricuspid annular plane systolic excursion and mortality in COVID-19 patients: A Meta-analysis

BACKGROUND

The evaluation of the tricuspid annular plane systolic excursion (TAPSE) is recommended to assess the right ventricular (RV) systolic function. We performed an updated meta-analysis of the association between TAPSE and short-term mortality in COVID-19 patients.

METHODS

MEDLINE and Scopus databases were searched to locate all the articles published up to May 1, 2021, reporting data on TAPSE among COVID-19 survivors and non-survivors. The difference of TAPSE between the two groups was expressed as mean difference (MD) with the corresponding 95% confidence interval (CI) using the Mantel-Haenszel random effects model. Both Q value and I2 statistics were used to assess heterogeneity across studies. Sensitivity analysis, meta-regression, and evaluation of bias were performed.

RESULTS

Twelve studies, enrolling 1272 COVID-19 patients (778 males, mean age 69.3 years), met the inclusion criteria and were included in the final analysis. Non-survivors had a lower TAPSE compared to survivors (MD =  -3.089 mm, 95% CI =  -4.087 to -2.091, p < 0.0001, I2  = 79.0%). Both the visual inspection of the funnel plot and the Egger's tests (t = 1.195, p = 0.259) revealed no evidence of publication bias. Sensitivity analysis confirmed yielded results. Meta-regression analysis evidenced that the difference in TAPSE between the two groups was only influenced by pre-existing chronic obstructive pulmonary disease (COPD, p = 0.02).

CONCLUSION

COVID-19 non-survivors have a lower TAPSE when compared to survivors, especially in COPD subjects. Current data suggest that the TAPSE assessment may provide useful information regarding the short-term prognosis of COVID-19 patients during the infection.

Early effects of ventilatory rescue therapies on systemic and cerebral oxygenation in mechanically ventilated COVID-19 patients with acute respiratory distress syndrome: a prospective observational study

BACKGROUND

In COVID-19 patients with acute respiratory distress syndrome (ARDS), the effectiveness of ventilatory rescue strategies remains uncertain, with controversial efficacy on systemic oxygenation and no data available regarding cerebral oxygenation and hemodynamics.

METHODS

This is a prospective observational study conducted at San Martino Policlinico Hospital, Genoa, Italy. We included adult COVID-19 patients who underwent at least one of the following rescue therapies: recruitment maneuvers (RMs), prone positioning (PP), inhaled nitric oxide (iNO), and extracorporeal carbon dioxide (CO2) removal (ECCO2R). Arterial blood gas values (oxygen saturation [SpO2], partial pressure of oxygen [PaO2] and of carbon dioxide [PaCO2]) and cerebral oxygenation (rSO2) were analyzed before (T0) and after (T1) the use of any of the aforementioned rescue therapies. The primary aim was to assess the early effects of different ventilatory rescue therapies on systemic and cerebral oxygenation. The secondary aim was to evaluate the correlation between systemic and cerebral oxygenation in COVID-19 patients.

RESULTS

Forty-five rescue therapies were performed in 22 patients. The median [interquartile range] age of the population was 62 [57-69] years, and 18/22 [82%] were male. After RMs, no significant changes were observed in systemic PaO2 and PaCO2 values, but cerebral oxygenation decreased significantly (52 [51-54]% vs. 49 [47-50]%, p < 0.001). After PP, a significant increase was observed in PaO2 (from 62 [56-71] to 82 [76-87] mmHg, p = 0.005) and rSO2 (from 53 [52-54]% to 60 [59-64]%, p = 0.005). The use of iNO increased PaO2 (from 65 [67-73] to 72 [67-73] mmHg, p = 0.015) and rSO2 (from 53 [51-56]% to 57 [55-59]%, p = 0.007). The use of ECCO2R decreased PaO2 (from 75 [75-79] to 64 [60-70] mmHg, p = 0.009), with reduction of rSO2 values (59 [56-65]% vs. 56 [53-62]%, p = 0.002). In the whole population, a significant relationship was found between SpO2 and rSO2 (R = 0.62, p < 0.001) and between PaO2 and rSO2 (R0 0.54, p < 0.001).

CONCLUSIONS

Rescue therapies exert specific pathophysiological mechanisms, resulting in different effects on systemic and cerebral oxygenation in critically ill COVID-19 patients with ARDS. Cerebral and systemic oxygenation are correlated. The choice of rescue strategy to be adopted should take into account both lung and brain needs. Registration The study protocol was approved by the ethics review board (Comitato Etico Regione Liguria, protocol n. CER Liguria: 23/2020).