**6. Treatment strategies for DSWI**

Even though treatment of DSWI has considerably evolved, a generally accepted treatment strategy remains controversial. Robicsek postulated three valid principles addressing this issue: first, that the infectious process should be brought under control within the shortest possible time, secondly, that adequate debridement and drainage of the infected area should occur, and third that sternal stability should be assured [86]. Until the 1960s, patients suffering from DSWI were treated conservatively with antibiotic therapy, limited drainage, or exposure of the sternotomy wound until closure with granulation tissue occurred [87]. Mortality rates then reached over 50% and survivors' quality of life was limited due to significant morbidity [87]. In 1964, Shumacker and Mandelbaum reported their experience with single-stage technique of wound debridement, primary sternal re-wiring and continuous antibiotic irrigation [88]. Their original method was consequently modified in terms of the type of antibiotic or antiseptic solution used including its amount, or the setting of indwelling drains for irrigation and suction [89-90]. Closed chest drainage became widely used with reported mortality from DSWI ranging from 4.8% to 28%, with an associated risk of primary therapy failure ranging from 12.5% to 48% [89,90-92]. Lee et al proposed in 1976 the use of an omental flap for covering infected sternotomy wounds [93]. Vital greater omentum was turned into the chest cavity following sternal debridement. It was suggested that well-vascularized omentum fulfills dead spaces, ensures high antibiotic levels, and yielded angiogenic and absorptive capacity [13,93]. Jurkiewicz et al first reported the use of muscle flaps, preferably the pectoralis flap, and radical sternal debridement in the treatment of DSWI in 1980 [94]. Consequently, 20 years of experience in the Emory group with 409 patients showed 8.1% in-hospital mortality and 5.1% primary therapy failure. 87.1% of procedures were done in single-stage fashion; the pectoralis major was used in 76.6%, rectus abdominis in 19.4%, and omentum in 2.2% [95]. This approach has received many modifications regarding the timing of wound closure, choice of flap, and type of advancement, with reported mortality ranging from 0% to 19% [96,97]. Comparing the omental to the pectoralis flap, Milano et al reported that the omental flap had lower mortality (4.8% vs. 10.5%, p<0.05), early wound related complications (9.5% vs. 27.7%,p<0.001), and in-hospital stay (10.7 vs. 18.8%, p<0.05) [98]. El Oakley and Wright suggested classification of DSWI based on the time of presentation, presence of risk factors such as obesity, diabetes or immunosuppressive therapy, and number of failed therapeutic attempts in 1996 (Table 3) [99]. The identification of five subtypes of DSWI seemed to be a relevant tool for choice of therapeutic method and patient prognosis. Adjusted to the El Oakley and Wright classification, closed chest irrigation has comparable mortality data for type I and II DSWI compared with radical sternal resection and concomitant flap, but with lower flaprelated associated morbidity [100-102]. Ringelman et al noted that at 48 month follow-up, 51% of patients had pain or discomfort, 44% had numbness, 42% complained of sternal instability, and 33% claimed to have shoulder weakness, when pectoral flap was used for reconstruction [103]. Closed chest irrigation carries a higher rate of therapy failure when used for type III, and particularly type IV and V El Oakley and Wright classification [104-107]. Thus, these patients might have benefit from more radical sternal debridement and employment of well-vascular‐ ized tissue to replenish residual defects. Flap-related morbidity may be addressed with less invasive techniques such as a laparoscopic greater omentum harvesting [108]. Atkins et al recently reported on the influence of sternal repair choice (pectoral, omental flap, or secondary closure) on long-term survival [109].

(Flexigrip™, Praesidia SRL, Bologna, Italy), titanium locked staples (Sternal Talon™, KLS Martin Group, US), and Poly-Ether-Ether-Ketone tapes (Sternal ZipFix system™, Syntes, Switzeland), all designed for parasteral fixation. Negri et al reported a significant reduction of mechanical dehiscence (2.8% vs. 0.2%, p=0.002), but the same risk of DSWI (1.2% vs. 2.4%) when thermoactive clips were compared with standard wire cerclage [78]. Snyder et al reported 5 years of experience with the SternaLock system™ for primary plating in high risk patients. Superiority of plate over wires was seen in the incidence of early presentation (<30 days) of SWI (0% vs. 12%, p<0.06) and shorter in-hospital stay (7 vs. 8 days, p=0.02) [79]. A pilot study published by Bennett-Guerrero et al showed insignificantly higher spirometry volume in the SternalTalon™ arm (67% ± 32%) versus the wire arm (58% ± 24%). Use of the Talon was associated with decreased use of opiates (21.3 ± 11.8 vs. 25.4 ± 21.6 mg, P = 0.44), duration of mechanical ventilation (0.5 vs. 1.0 days, P = 0.24) and hospital length of stay (4.5 ±

A promising method to reduce SSI seems to be the application of NPWT on surgically closed sternal wounds. A commercially available system (Prevena® Incision Management System, KCI, St. Antonio, USA) is used, with skin preservation through a semipermeable membrane that has contact with foam, and one proposal pump system with reservoir is added [81]. Limited clinical experience has shown a decreased risk of wound hematoma, seroma and SSI [82]. Other positive effects from wound application of NPWT might include promotion of microvascular flow and decreased tissue edema and myofibroblast activation [83]. Colli and Atkins et al reported no wound healing complications in patients at high risk for sternal wound infections after cardiac surgery, but both studies were retrospective and done on smaller cohort

Even though treatment of DSWI has considerably evolved, a generally accepted treatment strategy remains controversial. Robicsek postulated three valid principles addressing this issue: first, that the infectious process should be brought under control within the shortest possible time, secondly, that adequate debridement and drainage of the infected area should occur, and third that sternal stability should be assured [86]. Until the 1960s, patients suffering from DSWI were treated conservatively with antibiotic therapy, limited drainage, or exposure of the sternotomy wound until closure with granulation tissue occurred [87]. Mortality rates then reached over 50% and survivors' quality of life was limited due to significant morbidity [87]. In 1964, Shumacker and Mandelbaum reported their experience with single-stage technique of wound debridement, primary sternal re-wiring and continuous antibiotic irrigation [88]. Their original method was consequently modified in terms of the type of antibiotic or antiseptic solution used including its amount, or the setting of indwelling drains for irrigation and suction [89-90]. Closed chest drainage became widely used with reported mortality from DSWI ranging from 4.8% to 28%, with an associated risk of primary therapy failure ranging from 12.5% to 48% [89,90-92]. Lee et al proposed in 1976 the use of an omental flap for covering infected sternotomy wounds [93]. Vital greater omentum was turned into the

3.2 vs. 5.3 ± 4.0 days, P = 0.40) [80].

500 Artery Bypass

of patients, 10 and 57, respectively [84,85].

**6. Treatment strategies for DSWI**

There is limited data evaluating hyperbaric oxygen (HBO) therapy in the treatment of SWI, despite theoretical advantages, availability of HTO close to the cardiac surgical unit impedes its routine use [110]. Siondalski et al reported successful healing of 55 DSWI patients with no mortality, nevertheless therapy required 20-40 HBO sessions after surgical revision. HTO was taken as an adjunct therapy to perform radical debridement and muscle flap [111].



**Authors Follow-up Patients**

Doss et al [122]

Song et al [123]

Luckraz et al [124]

Fuchs et al [125]

Sjoegren at el [126]

Immer et al [127]

Berg et al [121]Retrospective 31 pts NPWT

**´cohort**

vs. 29 pts closed irrigation

vs. 22 closed irrigation

vs. 18 pts open packing

vs. 13 pts closed irrigation

vs. 33 pts open packing

vs. 40 closed irrigation/ open packing

Retrospective 22 pts NPWT

Retrospective 17 pts NPWT

Retrospective 27 pts NPWT

Retrospective 35 pts NPWT

Retrospective 61 pts NPWT

Retrospective 38 pts NPWT

vs. 17 sternectomy and flap

**Endpoints Results**

Current Challenges in the Treatment of Deep Sternal Wound Infection Following Cardiac Surgery

NPWT group had a lower risk of therapy failure (52 vs. 16%, p<0.05) and in-hospital stay (22 vs. 26 days, p<0.05), with comparable in-hospital mortality (6,9 vs. 6,6%, NS) to

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503

NPWT group had shorter overall length of therapy (17.2±5.8 vs. 22.9±10.8 days, p=0.01) and in-hospital stay (27.9±6.6 vs. 33.0±11.0 dnů, p=0.03), with comparable mortality (5 vs.

NPWT associated with shorter length of therapy ( 6.2 vs. 8.5 days, p<0,05), lower number of dresssing changes (3±2.5 vs. 17±8.6 , p<0.01), and comparable in-hospital

NPWT linked with lower therapeutic failure rate (15 vs. 30.7%, p<0.05), in-hospital mortality (7.5% vs. 18.5%, p<0.05) and overall cost of therapy (16 400 vs. 20 000 USD) compared with closed irrigation

NPWT led to faster bacterial decontamination of wounds (16 vs. 26 days, p<0.01), shorter length of therapy (21 vs. 28 days, p<0.01) and in-hospital stay (25 vs. 34 days, p<0.01) and better 1-year survival (97.1 vs. 74.7%, p<0,05)

NPWT had lower risk of therapy failure (0 vs. 15%,p<0.01), 90 day mortality (0 vs. 15%, p<0,01), and 1- and 5-year survival (93 vs. 82%, 83 vs. 59%, p<0.05) against conventional

NPWT led to shorter in-hospital stay (51.5±20.8 vs. 70.7±28.8 dnů, p<0.05), nonsignificantly lower in-hospital mortality (5.3 vs 11.8, NS) and better quality of life based on questionnaire SF-36 compared with

sternectomy and flap

closed irrigation

5%, NS) to closed irrigation

mortality (11 vs. 6%, NS)

compared with open packing

therapy

Primary therapy failure, in-hospital stay and

Primary therapy failure, in-hospital stay and

Primary therapy failure, number of dressing changes, in-hospital stay and mortality

Primary therapy failure, in-hospital mortality, and cost of therapy

Lenght to achieve sterile woud, length of therapy, in-hospital stay, and 1-year survival

Therapy failure, 1- and 5-year mortality

In-hospital stay and inhospital mortality, quality of life

mortality

mortality

**Table 4.** El Oakley and Wright classification of DSWI (modified from El Oakley et[99])

In 1997, Obdeijin et al described the first application of NPWT for treatment of DSWI in 3 consecutive patients [112]. They found that physical therapy contracted the wound, provided sufficient chest stability, and allowed patients to be extubated. Catarino et al reported the first retrospective comparison between NPWT and closed chest irrigation in 2000. In comparing 9 versus 10patients,theyfoundsuperiorityofNPWTinlengthofin-hospital stay(15vs. 40.5days, p=0.02) and therapy failure (0 vs. 5, p=0.03) [113]. Furthermore, Gustafsson et al and Fleck et al, fromthe two most activeEuropean centers (Lundand Vienna),reportedsimilarin-hospital and 30-day or 90-day mortality of DSWI patients, with 60% of all cases having class III according to ElOakley andWright[114,115]. Consequently,theLundgroupreportedsurvivaldata from 1,3, and5yearfollow-upwhichshowedcomparablesurvival(92.9%,89%,89%)withpatientswithout DSWI after CABG (96%,92%, 86%) and showed potential survival benefit of NPWT therapy unlikedataknownfromconventionaltherapy[18].Recentlypublisheddata froma largergroup of patients showed 1.1-5.4% mortality at 30 days and 8-15% 1 year mortality with a 2 to 6% risk of primary therapy failure [116-119]. The mean length of application of NPWT was 8 to 14 days withameannumberof4to6dressingchanges [116-119].Theamountofdressingusedbycenters has only minor variability in first-line application protocol, with the only differences reported being thematerialsusedforinterfacedressing andthe timing of woundclosure [116-119].It was suggested that low C-reactive protein level (<50 mg/l) might be a good indicator for timing of woundclosure[120].SincetheintroductionofNPWT,itscomparisonwithconventionaltherapy, closed chest irrigation or sternal resection and flap have been studied. So far, we have data only from retrospective comparative studies, with the compared arms being heterogeneous in number of patients, time periods and type of DSWI based on El Oakley classification. It was suggested that NPWT positively influenced the risk of primary therapy failure and survival of patients at short and long-term follow-up [18,46,121-138]. Outcomes of NPWT are DSWI causative pathogen independent, even comparing therapeutic response to MRSA and MSSA causedDSWI[139].Frommultivariableanalyses,obesity,renalfailureandsepsiswerecalculated as independent risk factors of NPWT failure [128,129]. Results of comparative studies and published meta-analyses are shown in Table 5.



**Class Description of DSWI**

502 Artery Bypass

Type IVB Mediastinitis type I, II, or III after more than one failed therapeutic trial Type V Mediastinitis presenting for the first time more than 6 weeks after operation

**Table 4.** El Oakley and Wright classification of DSWI (modified from El Oakley et[99])

In 1997, Obdeijin et al described the first application of NPWT for treatment of DSWI in 3 consecutive patients [112]. They found that physical therapy contracted the wound, provided sufficient chest stability, and allowed patients to be extubated. Catarino et al reported the first retrospective comparison between NPWT and closed chest irrigation in 2000. In comparing 9 versus 10patients,theyfoundsuperiorityofNPWTinlengthofin-hospital stay(15vs. 40.5days, p=0.02) and therapy failure (0 vs. 5, p=0.03) [113]. Furthermore, Gustafsson et al and Fleck et al, fromthe two most activeEuropean centers (Lundand Vienna),reportedsimilarin-hospital and 30-day or 90-day mortality of DSWI patients, with 60% of all cases having class III according to ElOakley andWright[114,115]. Consequently,theLundgroupreportedsurvivaldata from 1,3, and5yearfollow-upwhichshowedcomparablesurvival(92.9%,89%,89%)withpatientswithout DSWI after CABG (96%,92%, 86%) and showed potential survival benefit of NPWT therapy unlikedataknownfromconventionaltherapy[18].Recentlypublisheddata froma largergroup of patients showed 1.1-5.4% mortality at 30 days and 8-15% 1 year mortality with a 2 to 6% risk of primary therapy failure [116-119]. The mean length of application of NPWT was 8 to 14 days withameannumberof4to6dressingchanges [116-119].Theamountofdressingusedbycenters has only minor variability in first-line application protocol, with the only differences reported being thematerialsusedforinterfacedressing andthe timing of woundclosure [116-119].It was suggested that low C-reactive protein level (<50 mg/l) might be a good indicator for timing of woundclosure[120].SincetheintroductionofNPWT,itscomparisonwithconventionaltherapy, closed chest irrigation or sternal resection and flap have been studied. So far, we have data only from retrospective comparative studies, with the compared arms being heterogeneous in number of patients, time periods and type of DSWI based on El Oakley classification. It was suggested that NPWT positively influenced the risk of primary therapy failure and survival of patients at short and long-term follow-up [18,46,121-138]. Outcomes of NPWT are DSWI causative pathogen independent, even comparing therapeutic response to MRSA and MSSA causedDSWI[139].Frommultivariableanalyses,obesity,renalfailureandsepsiswerecalculated as independent risk factors of NPWT failure [128,129]. Results of comparative studies and

**Endpoints Results**

NPWT linked with shorter in-hospital stay (15 vs. 40.5 days, p=0.02) and lower therapy failure (0 vs. 5%, p=0.03) than closed irrigation

In-hospital stay, primary

therapy failure

Accepted risk factors: diabetes, obesity, immunosupressive therapy intake

published meta-analyses are shown in Table 5.

Retrospective 11 pts NPWT

**´cohort**

vs. 9 pts closed irrigation

**Authors Follow-up Patients**

Catarino et al [113]


**Authors Follow-up Patients**

Raja et al [136] Meta-analysis 13 papers

Fleck et al [135]

Sjoegren at el

Schimmer et al

Damiani G et al [138]

[137]

[18]

**´cohort**

vs. 198 closed irrigation/ open packing

focused on comparison of NPWT with conventional therapy

focused on comparison of NPWT with conventional therapy

focused on comparison of NPWT with conventional therapy

focused on comparison of NPWT with conventional therapy and chest

reconstruction options

**Table 5.** Analyses and Meta-analyse of comparison NPWT with conventional therapy

Retrospective 326 pts NPWT

Meta-analysis 12 papers

Meta-analysis 15 papers

Meta-analysis 6 papers

**Endpoints Results**

Current Challenges in the Treatment of Deep Sternal Wound Infection Following Cardiac Surgery

Primary therapy failure, in-hospital mortality

Primary therapy failure, in-hospital stay and

Primary therapy failure, in-hospital stay and

Primary therapy failure, in-hospital stay and mortality, evaluation of German hearts centers

Primary therapy failure, in-hospital stay and

Addressing specific complications of DSWI, it is seen that NPWT does not increase the risk of late infection recurrence. Reported rates of chronic fistulas after conventional therapy and NPWT were comparable between 8-12% [18,130,134,140,41], and long-term survival of these patients is negatively affected [140,142]. CONS was identified as a pathogen with a higher risk

mortality

mortality

protocols

mortality

survival (91.5% vs.76.7%, p<0,05, 87.2 vs.

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505

NPWT was associated with lower primary therapy failure (8.5% vs. 34% p<0.001), and in-hospital mortality (3.6% vs. 10%, p<0.05)

NPWT associated with lower primary therapy failure, shorter in-hospital stay, and lower in-

NPWT seemed to be effective at high-risk DSWI patients, but weak evidence for routine

NPWT is associated with lower therapeutic failure, and in-hospital mortality. Routinely applied as first-line treatment in 35% of

NPWT prone to have shorter in-hospital stay

hospital and 1-year mortality

first-line application in DSWI

German heart centers

and lower mortality

69.8%, P<0.05)


**Table 5.** Analyses and Meta-analyse of comparison NPWT with conventional therapy

**Authors Follow-up Patients**

Bailot et al [46]Retrospektive

Petzina et al [129]

504 Artery Bypass

Simek et al [130]

De Feo et al [131]

Assman et al [132]

Deniz et al [134]

Segers [128] Retrospective 29 pts NPWT

conventional and prospective for NPWT

Retrospective for conventional and propective pro NPWT

Retrospective 69 pts NPWT

Retrospective 74 pts NPWT

Retrospective 82 pts NPWT

Retrospective 47 pts NPWT

Vos et al [133] Retrospective 89 pts NPWT

vs. 83 pts closed irrigation

vs. 38 closed irrigation

vs. 24 open packing

vs. 43 pts closed irrigation

**´cohort**

vs. 34 pts closed irrigation

125 pts NPWT vs. 24 pts. open packing

vs. 49 closed irrigation

38 pts withNPWT vs. 28 pts closed irrigation

**Endpoints Results**

NPWT decreased primary therapy failure (27.6 vs. 58.9%, p<0.05), with comparable 30 day (3,5 vs. 2,9%, NS)and 1-year mortality (31.0 vs.

Lower mortality in NPWT group (4.8 vs. 14.1%, p=0.01), but insignificantly better 1,5, and 10 year survival(92.8 vs. 83.0%, 89.8 vs. 76.4%,

NPWT associated with lower therapeutic failure (2.9% vs.18.3% p<0.05) and in-hospital mortality (5.8% vs. 24.5% p<0.05), but comparable in-hospital stay (38 vs. 41 days,

NPWT had lower failure of primary therapy (5.8 vs. 39.2%, p<0.05), ICU stay (209.6±33.3 vs. 516.1±449.5 hours, p<0.01),and in-hospital (5.8 vs. 21.4%, p<0.05) and 1-year mortality (14.7 vs 39.2%, p<0.05), but comparable inhospital stay (40.2±16.3 vs. 48.8±29.2, NS)

NPWT group with lower risk of therapy failure (1.4 vs. 16.9%, p<0.001), shorter in-hospital stay (23.3±9 vs. 3.0.5±3, p<0,05), and lower inhospital mortality (1.4 vs. 3,6 %, p<0,.05) compared with closed irrigation

NPWT patients had shorter in-hospital stay (45.6 ± 18.5 vs. 55.2 ± 23.6 dnů, p<0.05), and lower in-hospital mortality (14.6 vs. 32.4 %,

NPWT led to shorter ICU stay (6.8±14.4 vs. 18.5±21.0 dnů, p<0.01), in-hospital stay (74.4±61.2 vs. 69.1±62.7 days, p<0.01), and lower in-hospital mortality (12.4 vs. 41.7%,

NPWT had insignificantly lower rate of primary therapy failure (2.1% vs. 4.7%, NS) and shorter in-hospital stay (18±9 vs. 24±10 days, NS), 90 days mortality significantly lower (8.5 vs. 23.2%, p<0.05) and better 1-, and 3-year

23.5%, NS) to closed irrigation

88.0 vs. 61.3%, NS)

NS) with closed irrigation

with closed irrigation.

p<0.05)

p<0.01)

Therapy failure, inhospital, and 1-year

In-hospital mortality and 1-,5-, and 10 years

Primary therapy failure, in-hospital stay and

Primary therapy failure, in-hospital stay, inhospital, and 1 year

Primary therapy failure, in-hospital stay and

In-hospital stay and

In-ICU and hospital stay

Primary therapy failure, in-hospital stay and 1-, 3 years mortality

mortality

survival

mortality

mortality

mortality

mortality

and mortality

Addressing specific complications of DSWI, it is seen that NPWT does not increase the risk of late infection recurrence. Reported rates of chronic fistulas after conventional therapy and NPWT were comparable between 8-12% [18,130,134,140,41], and long-term survival of these patients is negatively affected [140,142]. CONS was identified as a pathogen with a higher risk of recurrence; its low virulence, ability to create biofilm on metallic materials and inherent low sensitivity against prophylactically administrated antibiotics limit its eradication [41,143].

sternotomy wound unstable and employs the greater omentum or a muscle flap to fulfill any dead spaces [93,95,99,103]. This approach resulted in sternal instability and flap-related morbidity even when wounds were well-healed [154]. Some case reports have included the use of an autologous bone iliac crest graft or allogenous fibula graft to supply residual bone defects after DSWI [155,156]. Marulli reported the first use of an allogenous sternocostal bone graft for sternal reconstruction after chondrosarcoma removal [157]. Consequently, Dell'amore et al described four patients who were managed with the same technique with no wound healing complications and preserved chest wall stability [158]. The same authors proposed this technique for major post-DSWI defects, and [159] Kalab et al described the possibility of using an allogenous calva bone graft to address this issue. Allogenous bony grafts being fixed with transverse plates in mentioned cases [158-160]. Bone allograft usage for transplantation is under law restriction of local governments and European Association of Tissue Banks

Current Challenges in the Treatment of Deep Sternal Wound Infection Following Cardiac Surgery

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507

**8. Options in soft tissue defects reconstruction after DSWI in cardiac**

and conditions influencing the result must be taken into the account.

**Wound type Site of sternal wound Recommended flap for reconstruction**

Type B Lower half sternum Combined pectoralis major and rectus abdominis bipedicled flap Type C Whole sternum Combined pectoralis major and rectus abdominis bipedicled flap

In 1976, Lee et al were the first to report on the use of a pedicled greater omentum to fulfill the large defect after total sternectomy [93]. In 1980, Jurkiewicz et al introduced the bilateral pectoralis turnover flap for the same indication. Although various muscle flaps, along with their modifications have been reported, there is still debate about using muscular versus

**Table 6.** Classification of sternal wounds according to anatomical site (modified from Greig et al [165])

Type A Upper half sternum Pectoralis major

There are a broad range of possibilities for managing sternal soft tissue defects caused by DSWI. In the case of minor defects, a direct suture with tissue undermining can be effective. In wide dehiscence, some type of flap transfer is needed and excessive bone and soft tissue loss are dependent on close co-operation between the cardiac and reconstructive surgeons. There are two crucial conditions influencing the reconstructive strategy. The first condition is the size of the defect, while the second is the vascular network, which would optimally remain uncompromised after primary surgery or previously failed reconstructions. Although various flaps and their modifications have been proposed, none have been found to be a reconstructive option for all defects [97,163,164], therefore Greig et al suggested a simple classification system to address the choice of flap based on the size and location of the post-sternotomy defect (Table 6) [165]. It is not possible, however, to follow this classification system because various factors

[161,162].

**surgery**

With the rise in use of NPWT came an increased number of reported serious bleeding com‐ plications [144,145]. The risk of heart injury, particularly the right ventricle, bypass grafts or great vessels is well known from conventionally treated patients. Infectious erosion, displace‐ ment of heart structures towards sternal margins, or tractions of fibrosis adhesion were identified as potential mechanism of injury [146]. The incidence of these complications by conventional therapy was found to be between 2-14.8% [147-149], with data from a larger group of NPWT treated patients showing 2 to 5%, thus NPWT does not seem to increase the incidence of serious complications [116,118,127,130,146,150]. Mortality from these complica‐ tions varies between 25 to 70%, with emergency surgery as well as proper covering of mediastinal structures with interface dressing being crucial for management [146-148,150]. Several layers of paraffin gauze or silicone mesh are usually put below sternal margins on the heart and grafts. Development towards more suitable material, particularly rigid barrier for mediastinal protection is in progress, including mediastinal protection and preserved drainage ability of therapy [151].
