Effect of iron deficiency without anaemia on days alive and out of hospital in patients undergoing valvular heart surgery

Cardiopulmonary bypass associated acute kidney injury: better understanding and better prevention

Cardiopulmonary bypass (CPB) is a common technique in cardiac surgery but is associated with acute kidney injury (AKI), which carries considerable morbidity and mortality. In this review, we explore the range and definition of CPB-associated AKI and discuss the possible impact of different disease recognition methods on research outcomes. Furthermore, we introduce the specialized equipment and procedural intricacies associated with CPB surgeries. Based on recent research, we discuss the potential pathogenesis of AKI that may result from CPB, including compromised perfusion and oxygenation, inflammatory activation, oxidative stress, coagulopathy, hemolysis, and endothelial damage. Finally, we explore current interventions aimed at preventing and attenuating renal impairment related to CPB, and presenting these measures from three perspectives: (1) avoiding CPB to eliminate the fundamental impact on renal function; (2) optimizing CPB by adjusting equipment parameters, optimizing surgical procedures, or using improved materials to mitigate kidney damage; (3) employing pharmacological or interventional measures targeting pathogenic factors.

Days at home after surgery as a perioperative outcome: scoping review and recommendations for use in health services research

BACKGROUND

Days at home after surgery is a promising new patient-centred outcome metric that measures time spent outside of healthcare institutions and mortality. The aim of this scoping review was to synthesize the use of days at home in perioperative research and evaluate how it has been termed, defined, and validated, with a view to inform future use.

METHODS

The search was run on MEDLINE, Embase, and Scopus on 30 March 2023 to capture all perioperative research where days at home or equivalent was measured. Days at home was defined as any outcome where time spent outside of hospitals and/or healthcare institutions was calculated.

RESULTS

A total of 78 articles were included. Days at home has been increasingly used, with most studies published in 2022 (35, 45%). Days at home has been applied in multiple study design types, with varying terminology applied. There is variability in how days at home has been defined, with variation in measures of healthcare utilization incorporated across studies. Poor reporting was noted, with 14 studies (18%) not defining how days at home was operationalized and 18 studies (23%) not reporting how death was handled. Construct and criterion validity were demonstrated across seven validation studies in different surgical populations.

CONCLUSION

Days at home after surgery is a robust, flexible, and validated outcome measure that is being increasingly used as a patient-centred metric after surgery. With growing use, there is also growing variability in terms used, definitions applied, and reporting standards. This review summarizes these findings to work towards coordinating and standardizing the use of days at home after surgery as a patient-centred policy and research tool.

Nonanemic Iron Deficiency in Cardiac Surgery: A Retrospective Observational Study

OBJECTIVES

Anemia and iron deficiency in patients having cardiac surgery increases their perioperative risk. Nonanemic iron deficiency (NAID) in this group is less well-described. We aimed to investigate the incidence and outcomes of patients with NAID undergoing cardiac surgery.

DESIGN

Retrospective observational study.

SETTING

A single, tertiary referral center.

PARTICIPANTS

Adult patients who were preassessed and underwent cardiac surgery during the study period had data collected. We enrolled 537 patients enrolled and divided them into 4 groups according to hemoglobin and ferritin: NAID, nonanemic iron replete, iron-deficiency anemia (IDA), and non-iron-deficiency anemia.

INTERVENTIONS

This study was not interventional, but assessed the impact of anemia and iron deficiency on patient outcomes.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the incidence of NAID. Secondary outcomes included the number of patients who became anemic awaiting surgery, allogeneic transfusion burden, length of stay, postoperative complications, and death. 179 of 537 patients (33.3%) had NAID. Seventeen patients (9.5%) became anemic in the NAID group compared with 7 (3.3%) in the nonanemic iron replete group while awaiting for surgery (p = 0.02). Patients with NAID were more likely to receive allogeneic transfusions (33% vs 23%; p = 0.04) and had poorer recovery of hemoglobin at follow-up (13.2 ± 1.46 g/dL vs 13.9 ± 1.46 g/dL; p < 0.001).

CONCLUSIONS

NAID is common and can lead to progression to anemia and increased transfusion. Iron replacement should be considered in patients with NAID in the preoperative setting. A prospective interventional trial is required to demonstrate the benefit of being iron replete.

Associations Between Nonanemic Iron Deficiency and Postoperative Outcomes in Cardiac Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Preoperative screening for iron deficiency is a part of patient blood management protocols. This systematic review, meta-analysis, and meta-regression reviews the association between nonanemic iron deficiency and postoperative outcomes in patients undergoing cardiac surgery. We aimed to determine whether preoperative screening for nonanemic iron deficiency should be recommended in patients undergoing cardiac surgery.

METHODS

Electronic databases MEDLINE (Ovid), Embase (Ovid), and Scopus were searched from inception until December 9, 2022. Studies were considered for inclusion if they (1) used an observational study design; (2) enrolled adult patients undergoing cardiac surgery; and (3) included an iron-deficient and iron-replete group, defined using serum ferritin and/or transferrin saturation. The primary outcome was the length of acute hospital stay. Secondary outcomes included length of intensive care unit stay, requirement for allogeneic red blood cell transfusion, number of red blood cell units transfused, days alive and at home at postoperative days 30 and 90, all-cause postoperative complications, postoperative infection, mortality, and hospital readmission. Meta-regression was performed to assess the effects of study and patient-level factors on the associations between nonanemic iron deficiency and specific outcomes. Individual study quality was assessed using the Risk of Bias in Non-Randomized Studies of Exposures (ROBINS-E) tool. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) framework was used to determine the quality of evidence for each outcome.

RESULTS

Eight studies (2683 patients) were included. No significant association was observed between nonanemic iron deficiency and any of the primary or secondary outcomes except for an increased requirement for allogeneic red blood cell transfusion (odds ratio [OR], 1.39 [95% confidence interval, CI, 1.16-1.68; P < .001; I2 2.8%]). Meta-regression did not identify any potential sources of heterogeneity to explain variation in individual study results. The quality of evidence was rated as "low" or "very low" for all outcomes.

CONCLUSIONS

Few high-quality studies are available to assess associations between nonanemic iron deficiency and outcomes after cardiac surgery. Acknowledging these limitations, the presence of preoperative nonanemic iron deficiency was not associated with a change in the primary outcome of length of hospital stay, or any patient-centered secondary outcome compared to those without iron deficiency. There was an association with increased requirement for allogeneic red blood cell transfusion, but this did not impact the reported patient-centered outcomes.

Days alive and out of hospital at 30 days and outcomes of off-pump coronary artery bypass grafting

Days alive and out of hospital (DAOH) is a simple estimator based on the number of days not in hospital within a defined period. In cases of mortality within the period, DAOH is regarded as zero. It has not been validated solely in off-pump coronary artery bypass grafting (OPCAB). This study aimed to demonstrate a correlation between DAOH and outcome of OPCAB. We identified 2211 OPCAB performed from January 2010 to August 2016. We calculated DAOH at 30 and 60 days. We generated a receiver-operating curve and compared outcomes. The median duration of hospital stay after OPCAB was 6 days. The median DAOH values at 30 and 60 days were 24 and 54 days. The estimated thresholds for 3-year mortality for DAOH at 30 and 60 days were 20 and 50 days. Three-year mortality was higher for short DAOH (1.2% vs. 5.7% and 1.1% vs. 5.6% DAOH at 30 and 60 days). After adjustment, the short DAOH 30 group showed significantly higher mortality during 3-year follow-up (hazard ratio 3.07; 95% confidence interval 1.45-6.52; p = 0.004). DAOH at 30 days after OPCAB showed a correlation with 3-year outcomes. DAOH 30 might be a reliable long-term outcome measure that can be obtained within 30 days after surgery.

Iron deficiency in cardiac surgical patients

Iron is an essential element and involved in a variety of metabolic processes including oxygen transport, cellular energy production, energy metabolism of heart muscles, brain function, cell growth and cell differentiation. Preoperative anaemia is an independent risk factor for poor outcome. Recently, iron deficiency was considered only in the context of anaemia. However, negative consequences of iron deficiency in the absence of anaemia have been described for patients undergoing cardiac surgery. To date, the benefit of intravenous iron supplementation in these patients has been controversially debated. In this review, we discuss the latest progress in studies of intravenous iron supplementation in iron deficient cardiac surgical patients.