COMMENTARY
The in-hospital mortality rate of deep sternal wound infection (DSWI)
has decreased from 14-47% to 0-15% since the introduction of negative
pressure wound therapy (NPWT).1-4 While the incidence
of thoracic prosthetic graft infection is rare, the mortality rate is as
high as 25-75% due to severe infections that require radical and
extensive interventions due to aortic replacement, pseudoaneurysms,
aorto-esophageal fistulae, aorto-bronchial fistulae, and vegetation
inside the graft.5,6 Prosthetic graft infection rarely
occurs after aortic surgery via a median sternotomy, though this type of
infection also has a high mortality rate. However, the pathology of DSWI
with prosthetic graft infection is different than that of prosthetic
graft infection without DWSI, as DSWI often includes sternal
osteomyelitis, which may affect the treatment strategy. In addition,
prosthetic graft infections present in both the early and late
postoperative periods, and their presentation affects the treatment
strategy. Patients with a prosthetic graft infection in the early
postoperative period do not tolerate the radical and extensive
re-replacement of the prosthetic graft that requires a long operation
and circulatory arrest with or without hypothermia due to their critical
condition, insufficient recovery from the primary operation, and
bacteremia with or without sepsis. Umminer et al. reported that
graft-sparing techniques are safe and effective in patients with
early-onset prosthetic graft infection, especially within one month
after the primary operation.7 Therefore, graft sparing
salvage treatment for DSWI with prosthetic graft infection may be
preferable in high-risk patients, especially those with early onset
infections. However, a radical re-replacement of the infected graft with
a self-made tube, homograft, or rifampicin-soaked grafts remains the
best treatment option in patients with pseudoaneurysm, fistula
formation, and vegetation.8,9
Various salvage treatments for DSWI or DSWI with prosthetic graft
infection have been reported.3,4,10-13 The surgical
debridement of infected tissues and removal of purulent tissue must be
conducted immediately when DSWI with prosthetic graft infection is
diagnosed to reduce the bacterial population, control the infection, and
ameliorate the patient’s condition. NPWT is a standard treatment for
patients with DSWI after debridement as it stabilizes the thoracic cage
and controls the bacterial infection.3,4 Saiki et al.
reported the effectiveness of NPWT for patients with DSWI with
prosthetic graft infection.14 NPWT with continuous or
intermittent irrigation is a useful treatment for patients with DSWI
with prosthetic graft infection, resulting in good outcomes, decreased
mortality, and decreased recurrent infection
rates.10,11 A previous study reported that NPWT with
continuous irrigation improved hospital mortality from 50% to 16.7% in
patients with DSWI with prosthetic graft infection.10Continuous or intermittent irrigation and drainage contributes to the
control of bacterial infections by washing the purulent and necrotic
tissues, a strategy termed hydro-debridement. Takagi et al. proposed a
combination therapy of hydro-debridement with pulsed lavage and NPWT for
patients with DSWI with prosthetic graft infection.15In their study, intermittent hydro-debridement with pulsed lavage
consisted of a high volume of saline solution and 0.005% gentian violet
and significantly reduced the number of bacteria and the surgical site
infection rate.16 Moreover, pulsed lavage with gentian
violet facilitated the removal of necrotic tissues.17We suspect that hydro-debridement with pulsed lavage and gentian violet
enable the debridement in the entire mediastinum, including the gap
between the prosthetic grafts and the narrow space dorsal to the
prosthetic graft, which controls the local infection. However, this
strategy could result in ventricular arrhythmia or bleeding from the
organs.
Reconstruction with tissue flaps has also been reported as a useful
salvage treatment for patients with DSWI and DSWI with prosthetic graft
infection.4,13 Muscle or omentum tissue flaps are
created to fill wide-ranging tissue defects and promote a bactericidal
effect and wound healing. Omental flaps have been reported as superior
to muscle flaps due to their neovascularization ability, which promotes
immunological processes and enhances the antibiotic concentration; wound
secretion absorption; and the flexible shape that fills dead space.
However, the use of omental flaps may lead to hernia formation or
decreased vital capacity.13,18,19 In contrast, another
previous study reported that muscle and omental flaps are insufficient
to treat patients with DSWI and do not significantly reduce the
in-hospital mortality rate.20 Several previous studies
have reported excellent outcomes after NPWT followed by tissue flaps for
patients with DSWI.4 These findings suggest the
importance of controlling the local infection prior to the use of tissue
flaps. Therefore, NPWT with hydro-debridement allows for the eradication
and sterilization of the local prosthetic graft and mediastinum
infection. The use of NPWT with hydro-debridement as a bridge therapy to
omental flaps may be an alternative treatment for DSWI with prosthetic
graft infection in high-risk patients. Recently, multidisciplinary
strategies including collaboration with a plastic surgeon for proper
debridement, NPWT with irrigation, and tissue flaps have been
recommended for patients with DSWI with vascular graft infection, as
this strategy reduces mortality and has good
outcomes.10,11 Nevertheless, more studies are needed
to identify the effectiveness of this enhanced combination therapy for
patients with DSWI with prosthetic graft infection, as recurrent
infections may occur if the infected prosthetic graft is not
removed.