Deep sternal wound infection is a severe
complication after cardiac surgery and requires
special attention. While the incidence of DSWI after CABG is as low as 0.3 to 2.3%,[
11,
12] the
associated mortality rate can be as high as 36%.[
13]
Early closure of the sternal wound following a sharp
debridement in DSWI cases appears as a treatment
option to prevent secondary infection. Still, it may
also predispose to the spread of infection.[
2,
13] Sternal
closure following NPWT, which provides a clean
wound with granulation tissue, is a more reasonable
option.[
2] In DSWI cases after cardiac surgery, the
mortality rate was quite higher before NPWT, and
the mortality rate was noticeably decreased after the
use of NPWT.[
5,
13] Morisaki et al.[
13] reported that
mortality in DSWI patients was 38% before NPWT
use, and this rate decreased to 5% after NPWT use.
The in-hospital mortality was 14.7% in our study
population, which seems significantly lower than the
mortality rates in previous studies.[
13,
14] The beneficial
effects of NPWT on sternal wound healing could be
listed as follows: it maintains chest wall stability,
promotes granulation tissue, decreases wound edema,
and provides drainage of excessive and infected fluid
in case of a persistent infection. [
11,
15] Mobilization of
the patient is also possible with NPWT that provides
sternal stabilization.[
15,
16]
Deep sternal wound infection is often an early
complication of cardiac surgery.[1,5] The time interval
between cardiac surgery and diagnosis of DSWI
is a valuable parameter in treatment outcomes.
Delayed diagnosis may negatively affect the success
of treatment, whereas early diagnosis may prevent the
further spread of the infection.[1,11] Negative pressure
wound therapy is recommended to be initiated as soon
as possible, particularly if the sternal wound closure
is expected to be delayed.[6,11] The DSWI study by Buşra et al.[1] reported 21.3% mortality, and the mean
time between the diagnosis of DSWI after the first
cardiac surgery was 50.4±172.5 days. In our opinion,
relatively early detection of DSWI (35.8±30.2 days)
in our study plays a vital role in the slightly better
mortality rate (14.7%). In addition, NPWT was
initiated as soon as possible in all patients diagnosed
with DSWI, which could also explain the better
outcomes in our study.
According to the study by Lepelletier et al.,[17]
Staphylococcus aureus (S. aureus) is the most frequently
isolated microorganism in DSWI patients (40%),
followed by coagulase-negative staphylococci (30%).
Similarly, in our study population, the most isolated
microorganisms were coagulase-negative staphylococci
(38.2%), Klebsiella spp. (14.7%), and S. aureus (13.2%).
Although routine preoperative nasal swabs are obtained
from all patients, and mupirocin ointment is given to
eradicate staphylococcal nasal colonization as the
guidelines recommend, these measures cannot prevent
Staphylococcus spp. from being the most frequently
isolated microorganism in the DSWI cases.[17,18] In
methicillin-resistant S. aureus cases, it is necessary to
perform extensive and sharp tissue debridement to
prevent severe tissue destruction and inflammation
due to antibiotic resistance.[19]
Female sex, hypertension, diabetes mellitus,
obesity, active smoking, chronic pulmonary disease,
and chronic renal disease, which are considered risk
factors for DSWI in the literature,[2,4,15] were observed
at very high rates ranging from 30.9 to 66.2% in
our DSWI patients. Among these risk factors, the
only risk factor that was shown to be associated with increased mortality was the female sex in our study
population. In the literature review article for DSWI
patients presented by Phoon and Hwang,[15] female sex
was considered an independent risk factor for DSWI.
When we looked for the impact of female sex on
mortality in DSWI patients, no evidence was found
on the subject. Although we found female sex as a risk
factor for mortality in our study population of DSWI
patients, this issue needs to be supported by further
prospective studies.
The management of DSWI, particularly with
sternal instability, needs special care and attention,
with further interventions often necessary. Sternal
dehiscence may give rise to DSWI. The Robicsek
sternal closure technique is beneficial and helps to
provide sternal stability in case of multiple sternal
fractures.[15,20] If the primary closure of the sternum
cannot be achieved, reconstructive surgery by a
tissue flap can be an alternative.[14,21,22] We used the
Robicsek sternal closure technique to provide sternal
stability in cases with multiple sternal fractures. In
two of these patients, primary closure could not be
achieved, so reconstructive surgery by a muscle flap
was required.
Despite several studies and reviews, there are
no clear guidelines for DSWI. Dr. Lazar has
extensively studied the field of sternal wound
infections.[6,11,23] According to these studies, DSWI
patients should be managed with a multidisciplinary
approach, and NPWT should be initiated as soon as
possible. There are also several reviews that propose
an algorithm for the management of DSWI.[4,15,20]
However, a widely accepted algorithm does not
exist.
The retrospective design of the study is a
significant limitation. Since we present the outcomes
of NPWT after DSWI, there is no control group
to compare for morbidity and mortality in the
study; however, we could compare our results with
previously reported outcomes with DSWI. Two
patients with BITA use were both nondiabetics;
therefore, BITA use was not included in the statistical
analysis considering its limited number. Although the
single-center design of our study may be a limitation,
our clinic is a high-volume center serving a large
population, allowing us to share our experience with
a high number of yearly cases.
In conclusion, cardiac surgery patients can be
complicated with DSWI despite the increasing surgical experience and better outcomes. Negative
pressure wound therapy is a safe and reliable
treatment option in DSWI patients with or without
sternal dehiscence and is recommended to be
initiated as soon as possible. The most frequently
isolated microorganisms were coagulase-negative
staphylococci (38.2%), Klebsiella spp. (14.7%), and
S. aureus (13.2%). Female sex was the only factor
that was shown to be associated with increased
mortality in our DSWI patients.
Ethics Committee Approval: Ethical approval was
obtained from the hospital's academic review board and
Haydarpaşa Numune Training and Research Hospital
Clinical Research Ethics Committee (No: HNEAHKAEK
2022/103-3681). The study was conducted in
accordance with the principles of the Declaration of
Helsinki.
Patient Consent for Publication: Informed consent was
waived due to the retrospective nature of the study, and the
patient information had been anonymized before analysis.
Data Sharing Statement: The data that support the
findings of this study are available from the corresponding
author upon reasonable request.
Author Contributions: Idea/concept, design, literature
review, writing the article: F.A.B.; Idea/concept, design,
writing the article, references and fundings: M.B.; Idea/
concept, design, references and fundings: H.K.Ö.; Data
collection and/or processing, analysis and/or interpretation,
materials: A.Ö.; Idea/concept, control/ supervision, literature
review, critical review: E.M.T.M.
Conflict of Interest: The authors declared no conflicts
of interest with respect to the authorship and/or publication
of this article.
Funding: The authors received no financial support for
the research and/or authorship of this article.