Central venous oxygen saturation (ScVO2) facilitates the weaning of intra-aortic balloon pump in acute heart failure related to acute myocardial infarction

Comparison of Postoperative Outcomes Between Intra-aortic Balloon Pump and Levosimendan in Patients Undergoing Coronary Artery Bypass Graft: A Systematic Review and Meta-Analysis

This study was conducted to compare the postoperative outcomes between intra-aortic balloon pump (IABP) and levosimendan in patients undergoing coronary artery bypass graft (CABG) surgery. This meta-analysis was conducted following the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). For this meta-analysis, a literature search was performed on PubMed, Cochrane Central Register of Controlled Trials, and EMBASE from inception to July 15, 2023. Keywords used to search for relevant articles included "intra-aortic balloon," "levosimendan," and "cardiac surgery" along with their key terms and Medical Subject Headings (MeSH) terms. Outcomes assessed in this study included postoperative outcomes like all-cause mortality, postoperative arrhythmias, need for inotropic support, length of intensive care unit stay (ICU) in days, and duration of mechanical ventilation in hours. Other outcomes included two-hour, six-hour, and 24-hour postoperative central venous pressure (CVP), mean atrial pressure (MAP), and heart rate (HR). A total of eight studies were included in the pooled analysis. The pooled results found that the length of ICU stay and the duration of mechanical ventilation were significantly higher in patients receiving IABP. Additionally, the findings of this meta-analysis showed a higher need for inotropic support in patients receiving IABP compared to patients receiving levosimendan but the difference was statistically insignificant. However, no significant differences were found between the two groups in terms of mortality and arrhythmias. In conclusion, patients treated with levosimendan exhibited significant advantages, as they experienced shorter ICU stays and reduced duration of mechanical ventilation compared to the IABP group and less requirement for inotropic support.

The influence of intra-aortic balloon counter pulsation on central venous blood oxygen saturation

OBJECTIVES

We aim at identifying the changes in venous blood saturation values that associates intra-aortic balloon pump (IABP) in cardiac surgery patients with reduced left ventricular function (LVF).

METHODS

A retrospective observational study was conducted in a cardiothoracic intensive care unit (CTICU) in a tertiary cardiac center over 5 years in Qatar. A total of 114 patients with at least moderate impairment of LVF with ejection fraction (EF) less than 40% were enrolled. According to the association of IABP, patients were segregated into two groups with and without IABP (groups 1, 40 patients and group 2, 74 patients). Sequential arterial and venous blood gases were analyzed. The primary outcome was to analyze the changes in the central venous saturation (ScvO₂) in both groups and the secondary outcome was to analyze whether these changes affect the overall outcome in terms of intensive care unit (ICU) length of stay.

RESULTS

There was no significant difference between both groups with regard to age, preoperative EF, hemoglobin, and arterial oxygen saturation (SaO₂) in blood gases. Patients with IABP have a higher cScvO₂ when compared to the other group (71.5 ± 12.5 vs 63.5 ± 9.3, 68.3 ± 12.6 vs 60.1 ± 9.5, 62.7 ± 10.8 vs 55.63 ± 8.1, and 60.6 ± 7.6 vs 54.9 ± 8.1; p = 0.04, 0.05, 0.03, and 0.5, respectively). However, generalized estimating equations (GEE) analysis showed that compared with the participants showing that there is a decreasing trend in mean levels within the groups during follow-ups, overall difference between both groups' mean levels was not statistically significant.

CONCLUSIONS

In this study, we observed that after cardiac surgeries, patients with IABP had non-significant higher ScvO₂ when compared with a corresponding group with moderate impairment of LVF. Further prospective studies are required to validate these findings.

A Pragmatic Approach to Weaning Temporary Mechanical Circulatory Support: A State-of-the-Art Review

Temporary mechanical circulatory support (TMCS) provides short-term support to patients with or at risk of refractory cardiogenic shock. Although indications, contraindications, and complications of TMCS may guide device selection, optimal strategies for device weaning and explant remain poorly defined. Under the revised adult heart allocation policy implemented by the United Nations for Organ Sharing in October 2018, rejustification of heart transplant listing status includes demonstrating TMCS dependency with attempted device wean trials. However, standardized device-specific weaning and explant protocols have not been proposed or evaluated. This review highlights when to use percutaneous TMCS in cardiogenic shock, with a focus on weaning and explant considerations. Terminology for important concepts that guide device escalation, de-escalation, and explantation have been defined. Clinical, hemodynamic, metabolic, and imaging features have been defined, which can guide a tailored approach to TMCS weaning and explant based on the approach used at the Cleveland Clinic. A narrative review of published studies that have reported TMCS weaning protocols and survey results of member centers from CS-MCS working group centers is also provided. Future research is needed to better understand optimal timing and implementation of standardized protocols to achieve successful TMCS weaning and explant.

Monitoring of Tissue Oxygenation: an Everyday Clinical Challenge

Purpose of review

The aim of this article is to study the overview of pathophysiology and clinical application of central venous oxygen saturation monitoring in critically ill patients and during the perioperative period.

Recent findings

There are several clinical studies and animal experiments evaluating the effects of goal-directed hemodynamic stabilization on critically ill patients. Recent systematic reviews and meta-analyses found that advanced hemodynamic endpoints-targeted management has a positive effect on outcome in high-risk surgical patients. As all interventions aim to improve tissue oxygenation, it is of utmost importance to monitor the balance between oxygen delivery and consumption. For this purpose, central venous blood gas analysis provides an easily available tool in the everyday clinical practice. The adequate interpretation of central venous oxygen saturation renders the need of careful evaluation of several physiological and pathophysiological circumstances. When appropriately evaluated, central venous oxygen saturation can be a valuable component of a multimodal individualized approach, in which components of oxygen delivery are put in the context of the patients' individual oxygen consumption. In addition to guide therapy, central venous oxygen saturation may also serve as an early warning sign of inadequate oxygen delivery, which would otherwise remain hidden from the attending physician.

Summary

With the incorporation of central venous oxygen saturation in the everyday clinical routine, treatment could be better tailored for the patients' actual needs; hence, it may also improve outcome.

What is the optimum method of weaning intra-aortic balloon pumps?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: is weaning an intra-aortic balloon pump by volume superior to ratio reduction in terms of failure of weaning, inotropic support and haemodynamic parameters? A total of 667 papers were identified as a result of the search described below. Six papers were relevant to the question asked. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of the papers are tabulated. Little published evidence exists, although weaning by ratio is more common particularly in high-volume centres. The published data highlight the heterogeneity of weaning protocols not only between countries but also between hospitals in the same country. Current evidence is unable to establish any difference in clinical outcomes including mortality, reinsertion of intra-aortic balloon pumps and requirement for inotropic support between weaning by ratio, volume weaning and abrupt cessation. Despite this, the only randomized trial demonstrates improved haemodynamic profiles in those weaned by volume weaning. In addition, given the difficulty in obtaining clear clinical outcomes, N-terminal pro-brain natriuretic peptide and central venous oxygen saturation may be useful as surrogate markers for successful weaning.

Current and future applications of the intra-aortic balloon pump

PURPOSE OF REVIEW

The intra-aortic balloon pump (IABP) has been used for more than 40 years. Although recommended in a wide variety of clinical settings, most of these indications are not evidence-based. This review focuses on studies challenging these traditional indications and evaluates potentially new applications of intra-aortic counterpulsation.

RECENT FINDINGS

Recent studies have failed to confirm an improvement in clinical outcomes conferred by the IABP in patients developing cardiogenic shock after acute myocardial infarction. This issue is in need of further investigations. While conflicting results of several retrospective studies and meta-analyses have been published regarding the performance of the IABP in high-risk percutaneous coronary interventions, it has recently been found to improve the long-term clinical outcomes of patients in whom it was implanted before the procedure. Small, single-center studies have reported the use of the IABP as a bridge to transplantation or candidacy for left-ventricular assist device implantation. The recently reported feasibility and safety of its insertion via the subclavian or axillary arteries will facilitate these applications.

SUMMARY

The revisiting of available data and the performance of new, thoughtfully designed trials should clarify the proper indications for the IABP.