3.1. Baseline characteristics and operative data
During seventeen-years study period, between 09.2004 and 08.2021, 12,782 patients underwent cardiac surgery at our institution, of whom 407 (3.18%) required postoperative tracheostomy (See Table 1). 147 (36.1%) had early; 195 (47.9%) intermediate and 65 (16%) late tracheostomy. The three groups were similar regarding their baseline characteristics and operative data. 47 patients were underwent open, surgical procedure and 360 – percutaneous procedure. From a surgical procedure perspective, also there were no significant differences between the groups, regarding frequency and type of procedure, duration of cardiopulmonary bypass time and the cross-clamp time. (See Table 2.)
3.2. Outcome . Postoperatively, early tracheostomy was not associated with sternal wound infection There was a higher rate of deep sternal wound infection observed in the late tracheostomy group (p <0.001), although most of the patients in this grou
p had known, ongoing sternal or another infection at the time of tracheostomy (See Table 3). Only small number of patients were extubated and follow re-intubated (5.3%; 3.9% to 8% between the groups, p=0.278). Re-intubation itself has no influence on mortality. Incidence of sternal wound infection (SWI), both superficial and deep, was higher in the late group (18.4%) (p <0.001) to compare with early (6.8%) and intermediate (7.7%) groups, and infection in the most cases developed before tracheostomy (See Table 3). All sternal wound infection treated by opening of the wound at the bedside and/or application waccum device and defined as surgical complication Grade I according to Dindo classification7.
In our study, as we demonstrated, early, 30-day mortality was similar for all four groups. However, patients, who underwent early- and intermediate tracheostomy, demonstrating statistically significant lower mortality after 1- and 2-year. Also 5-year mortality were significantly low (55.8%; 68.7%; and 75.4%, respectively; p <0.001)
(See Table 3). Cox model is show, that covariate as time from operation to tracheostomy and age as significant factor for mortality (See Table 4).
4. Discussion
4.1. Main discussion. Up to 12% of the 800,000 patients who undergo mechanical ventilation in the United States every year require tracheostomies in the general ICU population8. Studies, performed in trauma populations, shoved incidence of tracheostomy as 24.7%9, in the patients suffering from acute myocardial infarction with cardiogenic shock – 5.7%10. In the patients after cardiac surgery rate varies between 1.4% and 6.2%2,11,12. In our study tracheostomy rate is 3.2%.
Tracheostomy after cardiac surgery was first described in 1964 by Robertson13. The percutaneous tracheostomy technique was introduced in1985 by Ciaglia, and today has proven to be a safer as standard surgical tracheostomy14. Over the last two decades, the utilization of tracheostomy for cardiac surgical patients requiring prolonged mechanical ventilation has become more frequent. The reasons for this trend are multifactorial, including an aging surgical population, increased prevalence of serious comorbidities in the surgical population and associated increased operative risk, increased number of patients undergoing redo surgery, increased utilization of ECMO, and broader surgical indications1,2,15.
Tracheostomy offers few advantages over orotracheal intubation. Tracheostomy reduces dead space and airway resistance, thereby decreasing the work of breathing and possibly allowing earlier liberation from mechanical ventilation 5,16. In addition, tracheostomy potentially reduces the need for sedation, which allows for patient mobilization, communication, nutrition and lowers the incidence of VAP16-19. Conversely, the possible disadvantage of early tracheostomy is the risk of sternal wound infection which may be explained by the close proximity of respiratory secretions to the sternotomy incision. Few studies showed increased the risk of sternal wound infection and mediastinitis in patients with a median sternotomy because of possible bacterial contamination from the tracheostomy20,21. Pilarczyk et al .22 reported a significantly higher incidence of deep sternal wound infection when tracheostomy is performed within 48 hours after surgery. But, current literature, however, seems to have disproved this association. In their series, Rahmanian et al .23 showed no correlation between early tracheostomy and deep sternal infection. Ben-Avi et al .1reported high incidence of SWI in the late group (more than 15 days). In a meta-analysis, Toeg et al .24 found that patients who had undergone early or late tracheostomy after cardiac surgery had comparable rates of sternal wound infection, and tracheostomy itself may not be a risk factor for SWI, but indicator of patient critical illness. In our study incidence of SWI, both superficial and deep was higher in the late group (18.4%) to compare with early (6.8%) and intermediate (7.7%) groups, and infection in the most cases developed before tracheostomy.
What remains controversial, however, is the optimal timing for performing the procedure. In post-cardiac surgical patients, a recent large national analysis of 33,765 patients undergoing tracheostomy by Sareh et al .2, demonstrated similar early postoperative outcomes (sternal wound infection, in-hospital mortality) in early (<14 days) versus late (14-30 days) tracheostomy groups. A smaller study by Affronti et al. 15, including 112 patients demonstrated shortened ventilation time and CSICU stay for the early tracheostomy group, but no differences in short or long-term mortality. Devarian et al .25concluded that early tracheostomy after cardiac surgery was associated with reduced cardiac morbidity (14% vs. 33%) and lower in-hospital mortality (21.1% vs. 40.4%), but unlike the present study, the authors included only isolated CABG or isolate valve procedures. In a single-center study, Ben-Avi et al .1 did not report any differences in terms of ventilation time, ICU stay, hospital stay, and 30-day mortality, but found lower mid-term mortality for the early tracheostomy group. In the systematic review by Adly et al .6, all studies were divided into three groups, according to tracheostomy time: within the 7, 14 or 21 days of endotracheal intubation. There was a significant difference in favor of early tracheostomy regarding reduced duration of mechanical ventilation, hospital-acquired pneumonia, less mortality rates and less duration of stay in ICU. Studies defining early tracheostomy as that done within 7 days of intubation had better results than those that done within 14 or 21 days of intubation.
We assume that not the tracheostomy per se is responsible for mortality. However, we do believe that it is not implausible to consider a link between a complicated postoperative course to mortality. We report the findings of our study, which tracheostomy time were found to be statistically significant regarding the long-term mortality. In addition, it is necessary to remember that we are talking only about a small, very specific group of patients with tracheostomy, and not about all patients.
In contrary, a randomized trial by Trouillet et al .12 compare immediate early percutaneous tracheotomy or prolonged intubation with tracheotomy 15 days after randomization and concluded that early tracheostomy provided no benefit in terms of mortality or infectious complications.
Overall, the survival rate for patients undergoing tracheostomy after cardiac surgery remains low. Ben-Avi et al .1described a 1- and 2-year survival rate of 34% and 32%, respectively. Similar results reported Ballotta et al .26. In this study the hospital mortality rate was 49%, survival rate for patients discharged from the hospital was 61% at 1 year, 49% at 2 years, 45% at 3 years, and 34% at 5 years. Krebs et al .11 reported, that tracheostomy patients had high short-term and long-term mortality, with a median survival of 6 months, 1-year survival of 41%, and 5-year survival of 29.1%. Affrontiet al .15 reported 1- and 2-year survival of 43.8% and 35.7% respectively, and Walts et al .27 described 30 days and 2 years survival 75% and 31% respectively.
The 407 patients in the present study represent the single-center cohort of post-cardiac surgical patients undergoing tracheostomy. The short-term mortality results reported here correlate with previously documented data. However, unlike previous studies, this study demonstrates a significant mid and long term survival benefit associated with earlier tracheostomy. These results, in conjunction with the other advantageous aspects of early tracheostomy suggest that earlier is better when a tracheostomy is required.