Utilization and outcomes of extracorporeal CO2 removal (ECCO2 R): Systematic review and meta-analysis of arterio-venous and veno-venous ECCO2 R approaches.

INTRODUCTION: Extracorporeal carbon dioxide removal (ECCO2 R) provides respiratory support to patients suffering from hypercapnic respiratory failure by utilizing an extracorporeal shunt and gas exchange membrane to remove CO2 from either the venous (VV-ECCO2 R) or arterial (AV-ECCO2 R) system before return into the venous site. AV-ECCO2 R relies on the patient's native cardiac function to generate pressures needed to deliver blood through the extracorporeal circuit. VV-ECCO2 R utilizes a mechanical pump and can be used to treat patients with inadequate native cardiac function. We sought to evaluate the existing evidence comparing the subgroups of patients supported on VV and AV-ECCO2 R devices. METHODS: A literature search was performed to identify all relevant studies published between 2000 and 2019. Demographic information, medical indications, perioperative variables, and clinical outcomes were extracted for systematic review and meta-analysis. RESULTS: Twenty-five studies including 826 patients were reviewed. 60% of patients (497/826) were supported on VV-ECCO2 R. The most frequent indications were acute respiratory distress syndrome (ARDS) [69%, (95%CI: 53%-82%)] and chronic obstructive pulmonary disease (COPD) [49%, (95%CI: 37%-60%)]. ICU length of stay was significantly shorter in patients supported on VV-ECCO2 R compared to AV-ECCO2 R [15 (95%CI: 7-23) vs. 42 (95%CI: 17-67) days, p = 0.05]. In-hospital mortality was not significantly different [27% (95%CI: 18%-38%) vs. 36% (95%CI: 24%-51%), p = 0.26]. CONCLUSION: Both VV and AV-ECCO2 R provided clinically meaningful CO2 removal with comparable mortality.

Impact of mechanical circulatory support on donor heart allocation: past, present, and future.

The United Network for Organ Sharing (UNOS) recently revised its heart allocation policy to address numerous shortcomings of the previous system. Implemented in 2018, the changes sought to reduce waiting list mortality, clearly define urgency status based on objective physiologic variables, decrease exemption requests, and introduce geographic modifications to ensure organ distribution favors the highest urgency candidates. In large part, UNOS policy revisions were driven by the growing use of continuous flow left ventricular assist devices (CF-LVADs) and the relevant device complications that led to an unacceptably high number of status exemptions. The new 6-tiered system assigns a comparatively lower urgency status to patients supported on CF-LVADs and higher urgency to patients supported on short-term mechanical circulatory assist (MCA) such as extracorporeal membrane oxygenation (ECMO) and intraaortic balloon pump (IABP) counterpulsation. LVAD use as bridge to transplant (BTT) therapy increased steadily throughout the preceding decade due to technological improvements and increased physician familiarity, but the recent policy changes introduce incentives for physicians to withhold this life-saving therapy in order to achieve higher urgency status for their patients. This paper will explore the technological evolution of MCA and the pertinent clinical trials that have led to their FDA approval as BTT and destination therapy. A review of the inception and development of the donor allocation system will be provided before examining available post-policy outcome data. Finally, we will highlight successes and shortcomings of the implemented changes before commenting on areas to potentially expand upon the existing policy.

Driveline damage and repair in continuous-flow left ventricular assist devices: A systematic review.

With mounting time on continuous-flow left ventricular assist device (CF-LVAD) support, patients occasionally sustain damage to the device driveline. Outcomes associated with external and internal driveline damage and repair are currently not well documented. We sought to evaluate the outcomes of driveline damage and its repair. Electronic search was performed to identify all relevant studies published over the past 20 years. Fifteen studies were selected for analysis comprising of 55 patients with CF-LVAD dysfunction due to driveline damage. Demographic and perioperative variables along with outcomes including survival rates were extracted and pooled for the systematic review. Most patients (53/55) were supported on HeartMate II LVAD (Abbott Laboratories, Abbott Park, IL). Internal damage was more commonly reported than external damage [69.1% (38/55) vs. 30.9% (17/55), P = .01]. Median time to driveline damage was 1.9 years [IQR 1.0, 2.5]. Most patients presented with a CF-LVAD alarm [94.5% (52/55)] and patients with internal driveline damage had a significantly higher rate of alarm activation compared to that observed for those with external damage [38/38 (100%) vs. 14/17 (82.4%), P = .04]. Patients with internal driveline dysfunction were more likely to experience component wear compared to those with external driveline dysfunction [10/38 (26.3%) vs. 0/17 (0%), P = .05]; 14.5% of patients (8/55) underwent external repair of the driveline, 5.5% (3/55) were treated with rescue tape, and 5.5% (3/55) were placed on an ungrounded cable, indicating a short-to-shield event had occurred. A total of 49.1% of patients (27/55) underwent CF-LVAD exchange, 5.5% (3/55) were weaned off the CF-LVAD to explant, and 5.5% (3/55) underwent emergent heart transplantation. The median length of hospital stay was 12 days [IQR 7, 12] and 30-day mortality rate was 14.5% (8/55). Driveline damage was more commonly reported at an internal location and despite being a well-recognized complication, mortality still appears high.