Mediastinitis is a surgical site infection arising during an intervention. The term “surgeon” originates from the ancient Greek kheiroynos, meaning “one who works with hands.” Thus, a surgical site infection could be considered facilitated by the “hand” of the surgeon. Since the days when we were called barbers—neither doctors nor physicians—surgical wound infection has been our most despised companion. It is the elephant in the room that no one wants to address due to the stigmas it carries.

The impact of surgical wound infections was significant enough that even the WHO took action in 2016 to reduce them. In Europe, such infections triple healthcare costs, increase hospital stays by nearly a week, and incur an annual cost of 5-10 billion euros. The outlook for mediastinitis has not improved much over the last decade. With an incidence of <2%, it carries a mortality rate of almost 10%, quadruples hospital stays, and increases costs by nearly five times. In an era where antibiotic resistance is more common than the exception, the future for these infections remains uncertain without proactive measures.

In today’s study, Gaudino et al. conducted a meta-analysis on mortality associated with mediastinitis following cardiac surgery. The primary objective was to assess overall mortality, while secondary objectives included evaluating in-hospital mortality, follow-up mortality, major adverse cardiovascular events, myocardial infarction, and the need for repeat revascularization. They performed a systematic search for studies examining short- and medium-term outcomes, comparing patients who developed mediastinitis with those who did not. They identified 24 studies, encompassing 407,829 patients, of whom 6,437 (1.6%) developed mediastinitis. The average follow-up was 3.5 years. Patients with mediastinitis had double the risk of overall mortality, follow-up mortality, major cardiovascular events, and triple the risk of in-hospital mortality (p < .001). There were no statistically significant differences in myocardial infarction or repeat revascularization, likely due to limited studies for these comparisons. Mediastinitis was also associated with longer postoperative stays and higher incidences of stroke, myocardial infarction, respiratory failure, and renal failure. The authors concluded that mediastinitis increases both mortality and clinical complications in the short and medium term.

COMMENTARY:

Meta-analyses hold a privileged place in scientific literature, second only to randomized clinical trials. However, the quality of a meta-analysis is only as good as the studies it builds upon. Their role is to synthesize knowledge and present it in a structured way to answer a clinical question. Gaudino et al. raise a relevant and pertinent question: they want to determine the mortality associated with mediastinitis following cardiac surgery. However, their clinical question is somewhat ambitious and thus broad. They encompass a highly heterogeneous patient profile, with studies that only examine isolated coronary surgery patients, others with only transplant cases, and many others with mixed cases. Additionally, there is a bias in the literature search as conference presentations were excluded, and no mention was made of searching grey literature (e.g., doctoral theses). The studies evaluated span almost three decades, incurring further bias by comparing articles from 1992 with those from 2021. Sufficient time has passed to incorporate surgical advancements, postoperative care improvements, and even antibiotic treatments that complicate comparisons, given that mediastinitis is, by definition, a multifactorial complication. Examining the consistency of results expressed in the forest plot reveals variability or heterogeneity. An I² statistic of 89% confirms heterogeneity and suggests interpreting the results with caution, as the validity of the model and the effect size are compromised.

Regardless of the study’s precision in answering the clinical question, it is clear that mediastinitis is a complication to avoid. No single intervention can resolve the problem of surgical site infections. Embracing the philosophy of Dave Brailsford (the British cycling team coach) and implementing “the aggregation of marginal gains” is essential. Preoperative measures, such as using antiseptic soap showers the night before surgery, preparing the chest skin with chlorhexidine, avoiding shaving the surgical site by using disposable clippers, administering antibiotics within the hour before incision, limiting the use of bone wax, handling tissues gently, minimizing operating room traffic, securing proper wound closure with good hemostasis and stable osteosynthesis, are some of the measures that should be implemented. I emphasize the use of negative-pressure wound therapy in both infected wounds and healthy ones with risk factors for dehiscence. This technology has existed for over a decade but was mentioned in only two of the 24 studies included in this article. Although the results on the benefits of negative-pressure therapy are inconclusive, its use has been on the rise. We hope that soon, with more data, its use will be standardized for both treatment and prevention of surgical wound infections.

In conclusion, as surgeons, we cannot settle for anything less than perfect wounds. By incorporating a comprehensive package of measures to reduce surgical site infections, we should aim for a zero-mediastinitis policy. We must do everything possible to eliminate infections from our wounds.

REFERENCE:

Perezgrovas-Olaria R, Audisio K, Cancelli G, Rahouma M, Ibrahim M, Soletti GJ, et al. Deep Sternal Wound Infection and Mortality in Cardiac Surgery: A Meta-analysis. Ann Thorac Surg. 2023 Jan;115(1):272-280. doi:10.1016/j.athoracsur.2022.04.054