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.