Reduction of Early Postoperative Morbidity in Cardiac Surgery Patients Treated With Continuous Veno-Venous Hemofiltration During Cardiopulmonary Bypass

Effects of interventions targeting the systemic inflammatory response to cardiac surgery on clinical outcomes in adults

BACKGROUND

Organ injury is a common and severe complication of cardiac surgery that contributes to the majority of deaths. There are no effective treatment or prevention strategies. It has been suggested that innate immune system activation may have a causal role in organ injury. A wide range of organ protection interventions targeting the innate immune response have been evaluated in randomised controlled trials (RCTs) in adult cardiac surgery patients, with inconsistent results in terms of effectiveness.

OBJECTIVES

The aim of the review was to summarise the results of RCTs of organ protection interventions targeting the innate immune response in adult cardiac surgery. The review considered whether the interventions had a treatment effect on inflammation, important clinical outcomes, or both.

SEARCH METHODS

CENTRAL, MEDLINE, Embase, conference proceedings and two trial registers were searched on October 2022 together with reference checking to identify additional studies.

SELECTION CRITERIA

RCTs comparing organ protection interventions targeting the innate immune response versus placebo or no treatment in adult patients undergoing cardiac surgery where the treatment effect on innate immune activation and on clinical outcomes of interest were reported.

DATA COLLECTION AND ANALYSIS

Searches, study selection, quality assessment, and data extractions were performed independently by pairs of authors. The primary inflammation outcomes were peak IL-6 and IL-8 concentrations in blood post-surgery. The primary clinical outcome was in-hospital or 30-day mortality. Treatment effects were expressed as risk ratios (RR) and standardised mean difference (SMD) with 95% confidence intervals (CI). Meta-analyses were performed using random effects models, and heterogeneity was assessed using I2.

MAIN RESULTS

A total of 40,255 participants from 328 RCTs were included in the synthesis. The effects of treatments on IL-6 (SMD -0.77, 95% CI -0.97 to -0.58, I2 = 92%) and IL-8 (SMD -0.92, 95% CI -1.20 to -0.65, I2 = 91%) were unclear due to heterogeneity. Heterogeneity for inflammation outcomes persisted across multiple sensitivity and moderator analyses. The pooled treatment effect for in-hospital or 30-day mortality was RR 0.78, 95% CI 0.68 to 0.91, I2 = 0%, suggesting a significant clinical benefit. There was little or no treatment effect on mortality when analyses were restricted to studies at low risk of bias. Post hoc analyses failed to demonstrate consistent treatment effects on inflammation and clinical outcomes. Levels of certainty for pooled treatment effects on the primary outcomes were very low.

AUTHORS' CONCLUSIONS

A systematic review of RCTs of organ protection interventions targeting innate immune system activation did not resolve uncertainty as to the effectiveness of these treatments, or the role of innate immunity in organ injury following cardiac surgery.

Continuous Ultrafiltration Enhances Recovery After Adult Cardiac Surgery With Cardiopulmonary Bypass: A Systematic Review and Meta-analysis

Background

Cardiac surgery with cardiopulmonary bypass is associated with systemic inflammation. Ultrafiltration used throughout the cardiopulmonary bypass time, continuously, is hypothesized to be an immunomodulatory therapy.

Methods

A systematic review and meta-analysis of randomized trials investigating continuous forms of ultrafiltration during adult cardiac surgery (CRD42020219309) was conducted and is reported following PRISMA guidelines. MEDLINE, Embase, CENTRAL, and Scopus were searched on November 3, 2021. The primary endpoint was operative mortality, and secondary outcomes included intensive care unit length of stay (ICU LOS), ventilation time, acute kidney injury or renal failure, and pneumonia. Each study was assessed for risk of bias using the Cochrane Risk-of Bias-Tool for Randomized Trials (RoB2) instrument. Outcomes were analyzed with inverse variance random-effects models and assessed for GRADE quality of evidence.

Results

Twelve randomized trials consisting of 989 adult patients undergoing coronary, valvular, or concomitant cardiac procedures were included. Compared to controls, patients receiving continuous ultrafiltration had no statistical difference in operative mortality; risk ratio of 0.32 (95% confidence interval [CI]: 0.10-1.03; P = 0.06). Reductions occurred in ICU LOS, by 7.01 hours (95% CI: 1.86-12.15; P = 0.008); ventilation time, by 2.11 hours (95% CI: 0.71-3.51; P = 0.003); and incidence of pneumonia, with a risk ratio of 0.33 (95% CI: 0.15-0.75; P = 0.008). There wasno difference in renal injury. The GRADE quality of evidence for these outcomes ranged from very low to low.

Conclusions

Continuous forms of ultrafiltration enhance recovery after adult cardiac surgery by reducing ICU LOS, ventilation time, and incidence of pneumonia. A multicentre randomized trial could confirm and generalize these findings.