The inflammatory response between miniaturised and conventional cardiopulmonary bypass after cardiac surgery in an Asian population

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.

Hemolysis and cardiopulmonary bypass: meta-analysis and systematic review of contributing factors

BACKGROUND

The use of cardiopulmonary bypass (CPB) is almost inevitable in cardiac surgery. However, it can cause complications, including hemolysis. Until now, there have not been any standards for reducing hemolysis from CPB. Therefore, this systematic review was conducted to determine the factors that increase or reduce hemolysis in the use of CPB.

METHODS

Keywords Earches (cardiac surgery AND cardiopulmonary bypass AND hemolysis) were done on PubMed databases and Cochrane CENTRAL from 1990-2021 for published randomized controlled trials (RCTs) that studied interventions on CPB, in cardiac surgery patients, and measured hemolysis as one of the outcomes. Studies involving patients with preoperative hematological disorders, prosthetic valves, preoperative use of intra-aortic balloon pumps and extracorporeal circulation, emergency and minimally invasive surgery are excluded RESULTS: The search yielded 64 studies that met the inclusion criteria, which involved a total of 3,434 patients. The most common surgery was coronary revascularization (75%). Out of 64 studies, 33 divided into 7 analyses. Remaining 31 studies were synthesized qualitatively. Significant decreases were found in centrifugal vs roller pumps for PFHb (p = 0.0006) and Hp (p < 0.0001) outcomes, separated vs combined suctioned blood (p = 0.003), CPB alternatives vs conventional CPB (p < 0.0001), and mini extracorporeal circulation (MiniECC) vs conventional CPB for LDH (p = 0.0008). Significant increases were found in pulsatility (p = 0.03) and vacuum-assisted venous drainage (VAVD) vs gravity-assisted venous drainage (GAVD) (p = 0.002).

CONCLUSION

The review shows that hemolysis could be caused by several factors and efforts have been made to reduce it, combining significant efforts could be beneficial. However, this review has limitations, such as heterogeneity due to no standards available for conducting CPB. Therefore, further research with standardized guidelines for CPB is needed to yield more comparable studies. Meta-analyses with more specific parameters should be done to minimize heterogeneity.

Conventional versus miniaturized cardiopulmonary bypass: A systematic review and meta-analysis

Objective

A meta-analysis of randomized controlled trials was performed to compare the effects of miniaturized extracorporeal circulation (MECC) and conventional extracorporeal circulation (CECC) on morbidity and mortality rates after cardiac surgery.

Methods

A comprehensive literature search was conducted using Ovid, PubMed, Medline, EMBASE, and the Cochrane databases. Randomized controlled trials from the year 2000 with n > 40 patients were considered. Key search terms included variations of “mini,” “cardiopulmonary,” “bypass,” “extracorporeal,” “perfusion,” and “circuit.” Studies were assessed for bias using the Cochrane Risk of Bias tool. The primary outcomes were postoperative mortality and stroke. Secondary outcomes included arrhythmia, myocardial infarction, renal failure, blood loss, and a composite outcome comprised of mortality, stroke, myocardial infarction and renal failure. Duration of intensive care unit, and hospital stay was also recorded.

Results

The 42 studies eligible for this study included a total of 2154 patients who underwent CECC and 2196 patients who underwent MECC. There were no significant differences in any preoperative or demographic characteristics. Compared with CECC, MECC did not reduce the incidence of mortality, stroke, myocardial infarction, and renal failure but did significantly decrease the composite of these outcomes (odds ratio, 0.64; 95% confidence interval [CI], 0.50-0.81; P = .0002). MECC was also associated with reductions in arrhythmia (odds ratio, 0.67; 95% CI, 0.54-0.83; P = .0003), blood loss (mean difference [MD], –96.37 mL; 95% CI, –152.70 to –40.05 mL; P = .0008), hospital stay (MD, –0.70 days; 95% CI, –1.21 to –0.20 days; P = .006), and intensive care unit stay (MD, –2.27 hours; 95% CI, –3.03 to –1.50 hours; P < .001).

Conclusions

MECC demonstrates clinical benefits compared with CECC. Further studies are required to perform a cost–utility analysis and to assess the long-term outcomes of MECC. These should use standardized definitions of endpoints such as mortality and renal failure to reduce inconsistency in outcome reporting.

Hemoadsorption does not Have Influence on Hemolysis During Cardiopulmonary Bypass

Cardiopulmonary bypass (CPB) induces hemolysis, which manifests as plasma free hemoglobin. We investigated in a post hoc analysis of a single-center, blinded, controlled study whether the use of a novel hemoadsorption device (CytoSorb, CytoSorbents Europe GmbH, Berlin, Germany) affects hemolysis during CPB. A total of 35 patients undergoing elective CPB surgery with an expected CPB duration of more than 120 min were included in the analysis. The hemoadsorption device was used in 17 patients (intervention group) and not used in 18 patients (control group). The primary outcome was differences of postoperative free hemoglobin and haptoglobin levels. As secondary outcomes, we investigated differences in postoperative lactate dehydrogenase and bilirubin levels. Postoperative free hemoglobin levels were not significantly different between the groups. However, there were statistically significant differences between the treatment and control groups in the median levels of haptoglobin (58.4 vs. 17.9 mg/dL, respectively; P < 0.01) and lactate dehydrogenase (353.0 vs. 432.0 U/L, respectively; P < 0.05) on postoperative day 1. Thus, in this study, we did not find an effect on hemolysis in patients treated with hemoadsorption, though lower haptoglobin level and higher secondary hemolysis markers on postoperative day 1 in patients not treated with the hemoadsorber may be an indication of some moderate effect of the device. Studies with larger samples are needed to clarify the significance of the small differences detected in this study.

Superior blood-saving effect and postoperative recovery of comprehensive blood-saving strategy in infants undergoing open heart surgery under cardiopulmonary bypass

BACKGROUND

Optimization of blood-saving strategies during open heart surgery in infants is still required. This study aimed to study a comprehensive blood-saving strategy during cardiopulmonary bypass (CPB) on postoperative recovery in low-weight infants undergoing open heart surgery.

METHODS

This was a prospective study of 86 consecutive infants (weighing <5 kg) with acyanotic congenital heart disease treated at the Tianjin Chest Hospital between March and December 2016, and randomized to the control (traditional routine CPB) and comprehensive blood-saving strategy groups. The primary endpoints were blood saving and clinical prognosis. The secondary endpoints were safety and laboratory indicators, prior to CPB (T1), after 30 minutes of CPB (T2), after modified ultrafiltration (T3), and postoperative 12 (T4), 24 (T5), 48 (T6), and 72 h (T7).

RESULTS

The total priming volume and banked red blood cells in the comprehensive strategy group were significantly lower than in the control group (P = .009 and P = .04, respectively). In the comprehensive strategy group, immediately after CPB, the amount of salvaged red blood cells exceeded the priming red blood cells by 40 ± 11 mL. Postoperatively, the comprehensive strategy group showed a significant decrease in the inotrope score (P = .03), ventilation time (P = .03), intensive care unit stay (P = .04), and hospital stay (P = .03) in comparison with the control group.

CONCLUSION

The comprehensive blood-saving strategies for CPB were associated with less blood use and favorable postoperative recovery in low-weight infants with congenital heart disease undergoing open heart surgery.