Delayed sternal closure is a well-established and widely practiced technique within congenital heart surgery that seeks to minimize the imposed physiologic stress of sternal closure at the index operation for select neonates and infants [4–6]. Although the benefits of DSC are well-accepted, potential deleterious effects of this strategy include but are not limited to prolonged duration of sedation and neuromuscular blockade, longer mechanical ventilation and intensive care unit admissions, and a potential increased risk for both superficial and deep infection [5, 12–15].
As demonstrated from our institutional data, the overall SSI rate following congenital heart surgery between January 2005 and December 2020 was 1.8%. Patients who underwent DSC following CHS had a significantly higher risk for SSI compared to patients who underwent PCC (8.7% vs 1.3%) with an open chest duration of 4 days or more being associated with a significantly increased incidence of SSI. These data model prior published experiences yet limited data is available on the inflection time point for significantly increased sternal infection in patients with prolonged DSC to guide clinician and surgical decision making. Prior retrospective study in a similar single-center congenital heart surgery patient population found a timepoint of 120 hours or 5 days to be associated with a significant increase in sternal wound infection, with a reported SSI incidence of 89% in infants with prolonged DSC open chest duration [16]. Within this study and others, age at operation and body weight were significant predictors of SSI. Additional studies have established age less than one year (OR 2.3), duration of cardiopulmonary bypass greater than 105 minutes (OR 1.92), aortic-cross-clamp time greater than 85 minutes (OR:5.61), and post-operative exposure to at least three separate red blood cell transfusions (OR 7.87) as factors significantly associated with an increase in the risk of SSI [1, 5, 17–18].
Reported incidences of SSI in congenital heart surgery following DSC range from 4–11%, consistent with our presented experience with a rate of 8.7% in DSC patients [19–22]. Both the composite incidence of SSI and that reported for our DSC cohort were below that presented in recent published analysis of the Society of Thoracic Surgeons-Congenital Heart Surgery Database. This prior study demonstrated an 18.7% incidence of SSI with DSC versus a 7% incidence of SSI in comparable neonates and infants with PCC [10]. This finding likely represents the effect of a collaborative initiative and standardized practice pattern in the management of neonates and infants undergoing both DSC and PCC at our institution. While the temporal effect of such practice patterns remains difficult to capture in a formalized analysis, the present study demonstrates an effective strategy that combines both prospective, standardized wound management and dedicated, retrospective analysis of outcomes in the management of sternal incisions following complex congenital heart surgery.
While a dedicated analysis of perioperative care pathway variables was beyond the scope of the present study, a review of our institutional incisional management strategy is warranted and remained consistent throughout the presented time-period. Patients undergoing congenital heart surgery at our institution undergo a pre-operative Hibiclens® (Molnlycke Heart Care, Norcross, Georgia) bath and receive both Mupirocin 2% nasal application for 5 days starting 2 days before surgery. A first-generation cephalosporin or Vancomycin is administered at the time of anesthesia induction and prior to skin incision and continued for 48 hours post-operatively. The anterior chest is prepared with either chlorhexidine (ChloraPrep™, BD Medical, Franklin Lakes, NJ) or Betadine® (Avrio Health, Stamford, CT) at the preference of the primary surgeon. Dermabond Prineo® (Johnson and Johnson, New Brunswick, NJ) is used as the principal wound dressing following standard three-layer sub-cuticular skin closure. Interrupted skin closure or wound V.A.C.® (3M/KCI, St. Paul, MN) skin management systems are utilized following DSC. Transthoracic echocardiography in open chest patients is performed as a sterile procedure with sterile probe coverings. Wounds are assessed daily by our surgical team led by trained nurse practitioners in wound care and immediate concerns regarding incision management are conveyed to the primary surgery to direct care accordingly. While many of the adopted practices have been translated from experiences within adult cardiothoracic surgery, the presented model demonstrates a reproducible approach that has achieved favorable outcomes in a diverse cohort of complex congenital heart surgical patients. Further critical analysis and consensus standardized practices are, however, needed to define efficacy and to establish causal relationships between favorable SSI preventative strategies and infection-free outcomes [23–25]. While many of these variables are inconsistently adopted across published multi-institutional datasets, the present study demonstrates a standardized, multi-disciplinary approach to incision management and defines delayed sternal closure duration as a potentially modifiable risk factor for SSI prevention.
While the presented analysis identifies DSC and open chest duration as variables significantly associated with increased incidence of SSI within a single institutional cohort, important limitations are acknowledged. A comprehensive analysis of our entire cohort was selected to minimize the potential for multiple comparisons bias, yet critical analysis of our DSC cohort focused on our neonatal population to limit confounding factors within the constraints of retrospective study. Further, the definition of wound infection remains complex and subjective factors are acknowledged. We, however, attempted to limit this confounding factor by making the diagnosis of SSI by multi-disciplinary committee review at a monthly meeting and in accordance with Center for Disease Control guidelines [26]. While prospectively practiced and retrospectively reviewed, we acknowledge the potential for selection and diagnostic bias. Further, we also accept the importance of minimizing rates of post-operative cardiac arrest and the inherent relationship that this may have with premature chest closure, particularly within vulnerable high-risk neonatal patients. While we have not observed an increase in our rates of post-operative cardiac arrests during the study period, ongoing institutional analyses are being dedicated to our neonatal patient population and chest closure practices on variables of post-operative resuscitation. We acknowledge that this critical aspect of surgical and clinical decision-making will support a continued role for DSC in infants undergoing complex congenital heart operations.
In conclusion, the present study demonstrates within a standardized, institutional cohort of congenital heart disease operations that DSC is associated with an increased risk of SSI. Further, temporal analyses of these data define an open chest duration of greater than 4 days as a potentially modifiable risk factor to minimize this morbidity for infants undergoing DSC. Standardized, prospective management and collaborative analysis of additional factors are needed. Multi-disciplinary clinician and surgical investment are critical to surgical wound management within congenital heart surgery to further limit the imposed morbidity and mortality of this feared complication with congenital heart surgery.