Table 1:
Best evidence papers
| Author, date, journal and country Study type (level of evidence) |
Patient group | Outcomes | Key results | Comments/weaknesses |
|---|---|---|---|---|
| Damiani et al. (2011), J Plast Reconstr Aesthet Surg, Italy [2] Meta-analysis of observational studies (level 3a) |
A meta-analysis was performed to assess the impact of VAC compared with conventional therapy on length of stay and mortality in patients with infected sternal wounds 6 studies were identified that included 321 patients of which 169 underwent VAC therapy and 152 had conventional therapy. Conventional therapy included debridement, reconstruction with muscle flaps, closed or open drainage and continuous irrigation |
Mortality | VAC therapy OR 0.61, [95% CI 0.29–1.27] better than conventional treatment No significant differences |
This meta-analysis showed that VAC therapy significantly reduced inpatient stay and tended to reduce mortality when compared with conventional treatment. The authors conclude that VAC is a valid alternative to conventional therapy because it reduces the duration of wound treatment and hospital stay without any significant impact on mortality rates Limitations: the included studies all employed different methods as their conventional treatment arm. Thus, the validity of drawing conclusions from such comparisons can be called into question |
| Length of stay (days) | Mean difference; −7.18, [95% CI −10.82 to −3.54] in favour of VAC therapy | |||
| De Feo et al. (2011), Asian Cardiovasc Thorac Ann, Italy [3] Retrospective cohort (level 3b) |
200 patients with deep sternal wound infections (DSWI) from 1979 to 2009 were included, Group A (n = 62; 1979–1994) was treated with conservative antibiotic therapy followed by surgery in case of failure. Group B (n = 83; 1995–2002) underwent wound debridement, closed irrigation and delayed plastic reconstruction. In case of failure, patients were managed with sugar and hyperbaric treatment. Group C (n = 55; 2002–2009), the treatment protocol included early surgical debridement, no <10 days of VAC therapy at a continuous pressure of −125 mmHg and reconstruction with a pectoralis muscle flap | In-hospital mortality | A: 19 (30.6%) B: 2 (2.4%) C: 1 (1.8%) Not significantly different between VAC and conventional therapy |
Those undergoing VAC therapy had significantly shorter in-hospital stay and C-reactive protein levels declined faster; however, there were no significant difference in mortality rates The authors recommend that ‘the most reasonable management protocol is based on early surgical debridement of the wound, vacuum application, followed by plastic reconstruction with pectoralis muscle flap’ |
| Length of stay (days) | A: mean 44 SD 9 B: mean 30.5 SD 3 C: mean 27.3 SD 9 Conventional therapy entailed significantly longer hospital stays (P < 0.05) |
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| Normal CRP within 7 days | A: 15(24.2%) B: 44 (53%) C: 39 (69%) Significantly faster rate of reduction in CRP in the VAC group when compared with conventional treatment (P < 0.05) |
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| Steingrimsson et al. (2012), Interact CardioVasc Thorac Surg, Iceland [4] Retrospective population based cohort (level 3b) |
43 patients with DSWI were included in the study. All patients were initially treated with intravenous antibiotics, surgical debridement and removal of sternal wires. 23 patients treated before July 2005 underwent CvT group, which involved surgical revision followed by twice daily open wound dressings with paraffin or chlorhexidine gauze with or without subsequent closed irrigation, until delayed primary closure can be achieved. In the other 20 patients negative pressure wound therapy (NPWT) was used as a first-line therapy (NPWT group). A paraffin gauze was placed at the bottom of the wound in order to protect the right ventricle and two layers of polyurethane foam (VAC GranuFoam, KCI Medical, San Antonio, TX, USA) was placed in the wound and a negative pressure of −125 mmHg was applied using the Vacuum Assisted Closure system (KCI Medical). The wound was reopened and dressings changed every 2–4 days. After granulation formation and clearance of infection delayed primary closure or secondary closure was performed | Length of stay in hospital (days) | CvT: mean 48, SD 23 NPWT: mean 47, SD 17 P = 0.84 |
This study showed that NPWT is associated with a significantly lower rate of early reinfections (persistent, Centres for Disease Control and Prevention (CDC) defined DSWI after at least one adequate treatment attempt) that required surgical revision as well as a trend towards lower 1-year mortality rates and fewer late chronic infections (infections diagnosed after discharge requiring surgical intervention that did not fulfill the CDC criteria for DSWI) The authors conclude that NPWT led to fewer surgical reinterventions and should be used as first-line therapy in most DWSI patients Limitations: the groups were both small and therapy was conducted over different time periods |
| In-hospital mortality | CvT: 1 (4%) NPWT: 0 (0%) P = 1 |
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| 1–year mortality | CvT: 4 (17%) NPPWT: 0 (0%) P = 0.07 |
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| Early reinfection | CvT: 8 (35%) NPWT: 1 (5%) P = 0.02 |
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| Chronic infection | CvT: 4 (17%) NPPWT: (0%) P = 0.07 |
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| Vos et al. (2012), Interact CardioVasc Thorac Surg, Netherlands [5] Retrospective cohort (level 3b) |
113 patients with post-sternotomy mediastinitis were treated either with VAC (n = 89) or open packing (n = 24). The team used a continuous negative pressure of 75–125 mmHg and treatment discontinuation was based on negative cultures | In-hospital mortality | VAC: 14 (12.4%) Open packing: 47 (41.7%) P = 0.0032 |
The VAC group had significantly lower in-hospital mortality rates and shorter durations of intensive care stay. Although overall hospitalization times were similar, a case can be made for using VAC as a cost saving method given the reduced time spent in intensive care However, despite the use of protective polyvinyl alcohol dressings, a patient suffered a right ventricular wall rupture secondary to the high negative pressures employed The authors conclude that ‘VAC therapy is superior to open packing, resulting in shorter intensive care stay and improved survival’ Limitations: retrospective, non-randomized analysis. Asymmetrical sample sizes with significantly younger patients included in the VAC group |
| Intensive care stay (days) Length of stay (days) |
VAC: mean 6.8, SD 14.4 Open packing: mean 18.5, SD 21.0 P = 0.0081 VAC: mean 74, SD 61 Open packing: mean 69, SD 62 P = 0.9778 |
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| De Feo et al. (2011), Tex Heart Inst J, Italy [6] Retrospective cohort (level 3b) |
83 patients with post-cardiac surgery mediastinitis from 1995 through 2001, treated with CvT, underwent debridement, closed chest irrigation and final plastic reconstruction with pectoral muscle flap in the majority of cases. 74 mediastinitis patients underwent extensive wound debridement followed by NPWT from 2002 onwards. NPWT was instigated for no <10 days and a continuous pressure of −125 mmHg was applied in all trial participants | In-hospital mortality | NPWT: 1 (1.4%) Conventional: 3 (3.6%) P = 0.35 |
2 homogeneous groups in terms of demographics and operative procedures underwent conventional or VAC therapy. VAC therapy produced lower early mortality rates (P = 0.35), lower reinfection rates (0.001) and shorter hospital stays (P = 0.02) There the authors state that ‘negative pressure wound therapy is advisable as first-choice therapy for deep sternal wound infection after cardiac surgery’ Limitations: patients were treated non-concurrently and improvements in medical care since 1995 may positively affect the outcomes in the NPWT group |
| Length of stay (days) | NPWT: mean 27.3, SD 9 Conventional: mean 30.5, SD 3 P = 0.02 |
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| Rate of reinfection | NPWT: 1 (1.4%) Conventional: 14 (16.9%) P = 0.001 |
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| Assmann et al. (2010), Thorac Cardiovasc Surg, Germany [7] Retrospective cohort (level 3b) |
A total of 192 patients with DSWI after median sternotomy were included in the study. 82 of these were placed on VAC therapy, while 38 patients were treated by intermittent open disinfectant irrigation and delayed secondary wiring. The CvT group had more beneficial baseline characteristics in terms of younger age, lower incidence of COPD and less complex cardiosurgical produces undertaken | Length of ICU stay (days) | VAC: mean 2.1 SD 1.2 Conventional: mean 3.9 SD 1.7 P < 0.05 |
Despite the VAC group having more disadvantageous baseline characteristics, the study reported lower mortality rates; shorter lengths of ICU and in-hospital stay as well as overall lower rates of postoperative complications (P < 0.05) including cardiovascular complications, sepsis and renal failure Thus they recommend: ‘VAC is a non-invasive, easily applicable and effective means to treat DSWI. Particularly patients at high risk of wound infections should be primarily treated using vacuum-assisted wound closure instead of conventional regimens Limitations: this was a retrospective non-randomized study with subjects treated over different time periods, thus causal interpretations may be difficult |
| Length of stay in hospital (days) | VAC: mean 45.6 SD 18.5 Conventional: mean 55.2 SD 23.6 P < 0.05 |
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| In-hospital mortality | VAC: 14.6% Conventional: 26.4% P < 0.05 |
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| Petzina et al. (2010), Eur J Cardiothorac Surg, Germany [8] Retrospective cohort (level 3b) |
In 118 patients with post-sternotomy mediastinitis, a group of 69 patients were treated with NPWT after debridement and irrigation. A continuous pressure of −125 mmHg was applied in all patients and the wound filler was changed every 2–4 days. NPWT discontinuation was guided by CRP and wound swabs. Another group of 49 were treated with CvT, which involved debridement, drainage and irrigation as well as transposition of the greater omentum and restabilization of the sternum There were no significant differences in preoperative demographics apart from a higher Body Mass Index (BMI) in the CvT group |
In-hospital mortality | NPWT: 4 (5.8%) Conventional: 12 (24.5%) P = 0.005 |
The in-hospital mortality and sternal reinfection rate were significantly lower in the VAC group. The in-hospital stay tended to be lower in the VAC group The authors conclude that NPWT should be the first-line treatment for deep sternal wound infections Limitations: retrospective cohort with patients treated over different time periods. Additionally, the patients in the VAC group required a mean of 5.5 (SD 1.6) operative procedures to complete the treatment whereas the conventional group only required one. On the one hand, this entailed more surgical trauma, but on the other it also meant more frequent debridement which is known to improve infection control |
| Reinfection rate | NPWT: 2 (2.9%) Conventional: 9 (18.3) P = 0.008 |
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| Length of stay in hospital (days) | NPWT: mean 38 Range 19–87 Conventional: mean 41, range 28–150 P = 0.08 |
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| De Feo et al. (2010), Asian Cardiovasc Thorac Ann, Italy [9] Prospective cohort study (level 3a) |
The study compared patients with post-cardiotomy staphylococcal deep sternal wound infection. A group of 39 patients treated with VAC therapy has been compared with 30 patients who received closed mediastinal irrigation and antibiotics. The VAC therapy was instigated for no <10 days and a continuous pressure of −125 mmHg was applied in all trial participants. Main outcomes investigated were hospital and wound healing | Hospital stay | VAC: mean 26.6 ± 8.4 Control group: mean 36.4 ± 3.2 |
Using VAC technology shortened hospital stay and wound healing time in deep sternal wound infections, including methicillin—resistant cases Limitations: prospective cohort study without blinding, randomization and a small sample size |
| Healing time | VAC: mean 13.5 ± 3.2 Control: mean 21.2 ± 16.4 |
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| Segers et al. (2005), Interact CardioVasc Thorac Surg, Netherlands [10] Retrospective cohort (level 3b) |
Retrospective data analysis identified 63 patients with post-sternotomy mediastinitis of which 29 were treated with topical negative pressure (TNP) and 34 with conventional closed drainage techniques. A continuous negative pressure of −125 mmHg was applied, as it was noted that intermittent pressure was associated with patient discomfort. Treatment withdraw was guided by CRP levels and cultures. Clinical outcomes were compared | Therapeutic failure rate (%) | TNP: 27.6% Conventional: 58.9% (P = 0.01) |
Negative pressure treatment was shown to be an effective approach Limitations: it is a retrospective, non-blinded study with a small sample size |
CvT: conventional therapy; OR: odds ratio; VAC: vacuum-assisted closure therapy.