Open sternotomy and DSC is a surgical technique that has been used in children to facilitate postoperative recovery. Cardiac compression, which may occur at the time of sternal closure, can lead to decreased cardiac output and hemodynamic instability. Riahi and colleagues were the first to point out the problem of postoperative cardiomediastinal disproportion in 1975
. Surgical manipulation of the heart leading to swelling in the pericardium and/or the pericardiomediastinal space, bleeding at the end of CPB, significant increase in heart size with severe ventricular dysfunction, reperfusion related myocardial edema and relentless arrhythmias are all severe complications of cardiac operations that preclude the sternum to be closed
[3–5]. They are often associated with a prolonged perfusion time and poor myocardial preservation
. Treatment by DSC provides time for recovery of myocardium and for treating the bleeding complications.
The potential for benefit from DSC is greater in small children, because of a larger cardiac size relative to the thoracic cavity. The utility of DSC in children has become evident over the last two decades. While shifting from palliative to earlier corrective surgery, procedures with longer CPB times on younger patients and DSC have become more common. Furnary and colleagues have recently demonstrated after re-openning the sternal incision, up to 59% increase in cardiac index and 18% rise in systemic blood pressure, without significant change in cardiac filling pressures could be obtained
. It has been suggested that DSC can be used to prevent the development of low cardiac output state
. Some of the pediatric cardiac surgery programs currently use an “elective sternal opening from the operating room” strategy for patients with marginal hemodynamic profiles. In many pediatric institutions it is routine to leave the sternum open prophylactically following long operations or specific procedures such as Norwood I for hypoplastic left heart syndrome
The optimal time to sternal closure remains unclear. In all cases the decision is being made usually by personally based criteria which are highly subjective. There are surgeons who generally leave the sternum open for at least 3 days, and close it any time from 2 to 14 days postoperatively
[7, 8]. There are also others who have aggressive approach to DSC, aiming for closure within 24 hours
. We don’t have strict criteria for the timing of the sternal closure. We don’t want to prolong the closure time over 3 days for infection purposes; however we usually close the chest when the patient becomes hemodynamically stable. In fact SCT prolonged up to 10 days in one of our patient who was then died to septicemia. The mean SCT in our study was 2.97 days.
Many techniques for the maintenance of an open sternum have been described in the literature including direct closure of the skin, or adaptation of the skin with a latex membrane (Esmark Bandage) sewn to the skin edges or VAC treatment
.We prefer a transparent nylon serum bag. It is easy to handle, cheap and helps monitor the bleeding and clot evacuation to avoid tamponade.
Potential risks of delayed sternal closure include sepsis, mediastinitis, bleeding, and late sternal instability. Infectious complications are already well-known contributors to postoperative morbidity and mortality after pediatric open heart surgery
. Kagan and colleagues demonstrated that an American Society of Anesthesiologists score of 4 or greater was risk factor for development of mediastinitis
. Tabbutt found mortality as 19%, surgical site infection as 6.7% and mediastinitis as 3.9% in his study of delayed sternal closure in pediatric patients.
. Shin reported postoperative infection and sterile wound dehiscence rate in DSC patients as 11% and 9%, respectively
. These sternal wound infections have been associated with longer postoperative stay
[8, 13–15]. The group of patients undergoing DSC are believed to have an increased risk for infection because they have predisposing factors such as: prolonged CPB time, low cardiac output, massive transfusion and the need for multiple re-explorations of the chest. A review of the literature reveals that the incidence of wound infection after DSC is generally less than 10%
. Some have reported that DSC is not associated with an increase in surgical site infections
[6, 8, 14, 16–19], besides some authors claim that wound complications are reduced in DSC technique
. Others report DSC as a significant risk factor for bloodstream and surgical site infections
[8, 13]. Das reported a fourfold increased risk of developing bloodstream infection in the DSC group.
In Woodwards’ study determining the rate of mediastinitis among the pediatric cardiac centers, 38 (43%) of the 89 centers were enrolled in the study. Woodwards reported 8,774 pediatric congenital procedures with a mean mediastinitis rate of 1.53%. The study concluded that DSC was not associated with increased incidence of mediastinitis. Variations in preoperative measures, antibiotic regimens, and wound care among these centers didn’t statistically influence the incidence of mediastinitis
. Between July 2007 and September 2011, 1100 pediatric cardiac operations were performed in our center. The total number of mediastinitis cases was 12 (1.09%) in our cohort in which 4 cases initially had undergone delayed sternal closure [4 out of 38 DSC cases (10.5%)]. The difference between the rates of mediastinitis in two different techniques is statistically significant. Unlike Woodwards and colleagues, we detected strong correlation between DSC and mediastinitis in our study.
It should be kept in mind that most studies of DSC, including ours, have evaluated children of all age groups along with the younger infants who may well be at a higher risk of septic complications. When the mean ages of mediastinitis cases in our center were compared, the mean age in DSC group is less than the mean age of the rest of the mediastinitis cases (23 to 342.5 days); however the difference was not found to be statistically meaningful due to high standard deviation (p = 0,248). However, age was not shown to be risk factor for mediastinitis in this study, instead SCT was associated with increased rate of mediastinitis. CPBT,CCT and ICU stay time were not related to mediastinitis risk.
Prolonged SCT was also shown to be a risk factor for postoperative infection. The infants with open chest are potentially critically ill for a variety of reasons that led to DSC. This may itself be a factor contributing to prolonged ICU stay which we also showed to be strongly related with high rate of postoperative infections in our study. The most common microorganism we isolated from the cultures was gram negative which is in agreement with the literature
[8, 13, 21].
Our study showed that longer durations of CPB and cross clamp was associated with longer SCT and high lactate levels before closure indicating the negative compromise of CPB on hemodynamics. With respect to changes in key physiologic parameters over time, we found that although mean heart rate and left atrial pressures were unchanged, mean blood pressure increased and inotrope score decreased in 12 hours after sternal closure which was in contradiction with Tabbutt and Horvath’s studies suggesting decrease in hemodynamic performance after sternal closure