Hernia DOI 10.1007/s10029-014-1312-y
ORIGINAL ARTICLE
Positive outcomes with negative pressure therapy over primarily closed large abdominal wall reconstruction reduces surgical site infection rates A. Gassman • A. Mehta • E. Bucholdz • A. Abthani • O. Guerra • M. M. Maclin Jr T. Esposito • C. Thomas
•
Received: 1 August 2013 / Accepted: 12 September 2014 Ó Springer-Verlag France 2014
Abstract Purpose There is a significant morbidity associated with abdominal wall reconstruction (AWR) with a need for overall improvement during the post-operative management. Scientific literature has proven the use of negative pressure therapy (NPT) in wound healing for orthopedic and cardiac surgery with limited data present on its role in AWR. The goal of this study was to examine whether primary wound events were different between patients who had primary closure with NPT versus patients who only had primary closure after AWR. Methods This retrospective study examined the rate of post-operative complications in all open-complex AWR that were done in a similar fashion between May 2008 and July 2011 at two large university teaching hospitals. Wound closure was stringent upon attending surgeon preference without randomization. Results There were a total of 61 patients who met inclusion criteria with an average age of 54 and 60 % were women.
A. Gassman Division of Plastic and Reconstructive Surgery, UCLA Department of Surgery, David Geffen School of Medicine, Los Angeles, CA, USA A. Mehta (&) E. Bucholdz T. Esposito C. Thomas Department of Surgery, Loyola University Medical Center, Maywood, IL, USA e-mail: [email protected] A. Abthani Department of Surgery, Northeast Ohio Medical University, Rootstown, OH, USA O. Guerra M. M. Maclin Jr Department of Surgery, Missouri Baptist Medical Center, St. Louis, MO, USA
Thirty-two patients had primary closure and 29 patients had primary closure with NPT. The mean length of follow-up was 167 days for both groups. The type of wound closure had an effect on the rate of hernia recurrence and surgical site infections. The application of NPT leads to lower hernia recurrence rate of 25 versus 3 % and the type of wound closure had a profound effect on the rate and type of SSI. Conclusions The data presented in this study demonstrates a potential advantage for adjunctive NPT in patients undergoing AWR. There is an associated decreased incidence in the overall rate of SSI and hernia recurrence with the use of NPT in those patients undergoing AWR. These results show an advantage for adjunctive NPT. Keywords Negative pressure therapy Abdominal wall reconstruction
Introduction Incisional hernia remains a common complication after abdominal surgery, and no consensus exists on optimal treatment. Many operative techniques for herniorrhaphy are available. These include simple primary suture repair, prosthetic implantation, or autologous tissue closure, and most options can be performed by either open or laparoscopic approaches [1–12]. Local wound complication rates are high for complex abdominal wall reconstruction (AWR). Despite a myriad of treatment options, there still exists significant morbidity associated with incisional hernia repair such as surgical site infections (SSI), seromas, hematomas, hernia recurrence and mesh complications often requiring removal. There is an obvious necessity for improvement in the post-operative management to alleviate the morbidity associated with these repairs.
123
Hernia
Negative pressure therapy (NPT) has become an accepted intervention in wound healing with scientific literature supporting its efficacy in a variety of wound types [13]. It has been used in the field of orthopedic surgery to decrease hematoma formation, increase the mechanical strength of dermal wound closure, and improve the clinical appearance of post-operative scars [14]. Additionally, in cardiac surgery, the use of NPT after sternotomy has been shown to decrease wound infections [15]. One report suggested that the use of NPT decreased SSI in patients undergoing laparotomy for oncologic resection [16]. The advantages of NPT are multifold with respect to increased bacterial clearance, tissue perfusion rate, and promotion of granulation tissue formation in the wound bed [17]. The current standard for incisional hernia repair is a reinforced repair. To alleviate tension across fascia, mesh derived from either synthetic or biologic material is placed to span or buttress the hernia defect and recreate structural integrity. Despite significant advantages, permanent synthetic mesh has drawbacks including: increased risk for visceral adhesions to the repair site, erosion into the bowel, enterocutaneous fistulae and/or bowel obstruction, extrusion of repair material, infection, seroma, and wound dehiscence [4]. Component separation of abdominal wall musculature to close fascial defect has also been described. However, re-herniation rates have been described up to 32 % after unreinforced, myofascial advancement flaps. Skin flap necrosis, seroma formation, and wound infection have all been reported as complications after this method of abdominal wall reconstruction. Although mesh reinforcement of component separation repairs reduces recurrence rates, complications such as hematoma and infection have been reported with rates of 16.7–63 % [10, 18]. Large and complex abdominal wall defects are requiring surgeons to push the limits of repairs. AWR with reinforcement is an excellent choice for the large midline defect, however, it incurs at the large risk of wound events. Initial closure of abdominal wounds requires a great deal of flexibility. There is limited data describing the use of NPT as an adjunct to primarily closed AWRs. To verify this growing body of literature, we compared 7 days of NPT to closed incisions versus standard dressings after AWR. We tested whether primary wound events such as SSIs, hematoma and seroma formation, skin flap necrosis and mesh removal were different between patients who had primary vacuum closure (PVC-primary closure with NPT) versus patients who only had primary closure (PC).
Methods This retrospective institutional review board (IRB) approved study examined the rate of post-operative
123
Fig. 1 a Primary closure of midline incision after AWR with staples. b Application of NPT over midline incision after closure
complications in all open, complex AWR performed between May 2008 and July 2011 at two large university teaching hospitals. IRB approval was obtained at each hospital. Two different surgeons performed the AWR where one surgeon’s practice was at Loyola Medical Center in Maywood, IL, and the two other performed the operation at Missouri Baptist Medical Center in Saint Louis, MO. Patient selection The hospital operative logs were queried by CPT code to identify a retrospective cohort of patients who underwent complex AWR requiring the use of biologic mesh [200 cm2. All patients underwent AWR with PC of the skin and operations were performed under the direction of a single attending surgeon at his respective hospital. Patients were selected to undergo PC or PVC based on surgeon preference. The cases in this series were clean. Information on demographics, co-morbid diseases, and medication use was also collected.
Hernia
Surgical technique All incisional hernias were repaired with an open technique. Similarity in operative methods was compared through chart review of each surgeon’s operative reports. After thromboembolism prophylaxis and perioperative antibiotics administration, each patient was administered general anesthesia. After lysing intra-abdominal adhesions when necessary, all patients underwent intraperitoneal underlay with Strattice (Lifecell/KCI) porcine acellular dermal matrix secondary to surgeon preference. The biologic mesh was sized to achieve at least 5 cm of underlay circumferentially around the fascial defect. Interrupted transfascial absorbable 0 or 1 PDS sutures were used to circumferentially fix the mesh as a wide underlay by elevating wide skin flaps. All patients had a variant of fascial closure. Fascia was completely re-approximated in the midline and edges were approximated over the mesh. In the cases where fascial closure was not possible, a component separation was performed as described by Ramirez et al. to aid in further fascial closure [19]. Partial fascial closure over the mesh was done when there was an increase in abdominal pressure as manifested by increased ventilator airway pressures ([32 mmHg). As each abdominal wall had varying level of compliance secondary to lateral muscular retraction, and reconstruction technique was similar, mesh size was used as a relative measure to compare defect size. Closed suction drainage (3–5 Jackson-Pratt or Blake drains) was placed in all cases. Drains were placed medially between the fascia and mesh as well as laterally in each gutter underneath the skin flaps. Drains remained in place until fluid output was less than or equal to 30 ml per day. They were typically removed in clinic after hospital discharge. All prior scar tissue, hernia sac, previously placed mesh and devitalized tissue was removed prior to closure. PC or PVC methods of skin closure were employed after copious irrigation and hemostasis. Wounds closure method was based on attending surgeon preference, and no randomization was employed. Primarily closed wounds had the skin edges approximated with stainless steel staples and dry occlusive dressings. The PVC patients received the same, stapled, primary skin closure with topical NPT as an overlay adjunct. These patients had a KCI commercial vacuum-assisted closure (VAC) device applied in a linear strip along the length of their closed incision (Fig. 1a, b). Care was taken to protect the underlying skin with either a layer of Adaptic (Johnson & Johnson) non-adhering dressing or perforated silastic sheets. The black polyurethane foam was cut as the same width as the protective skin dressing. Once complete adhesion and seal were certain, the wounds then received 7 days of continuous 125 mmHg
Table 1 Patient population similarities between both groups Population characteristics
Wound closure
Risk factor
Primary (n = 32)
PVC (n = 29)
Chisquared
Patient derived risk Gender (female)
17
21
0.118
Obesity (BMI [30) Current smoker
10 5
21 3
0.002 0.708
HTN
18
10
0.129
CAD
8
3
0.302
PVD
1
1
1.000
DM
12
8
0.585
Immunosuppression
2
1
1.000
13
11
0.797
Prior surgery Prior hernia repair with mesh Prior intra-abdominal infection
9
20
0.002
Ostomy prior or present at the time of surgery
14
7
0.774
Intra-abdominal infection at the time of surgery
4
3
0.538
Prior abdominoplasty
2
1
1.000
Operative details Component separation
16
19
0.306
Average CDC wound classification (1–4)
2.53 n
2.62 n
0.56 (SD)
Bold values indicate statistically significance HTN hypertension, CAD coronary artery disease, PVD peripheral vascular disease, DM diabetes mellitus, CDC center for disease control and prevention
NPT with the VAC device. At 7 days, the NPT was removed. PC wounds were otherwise followed in the same fashion as in the PVC group. Data collection The study population’s electronic medical records were reviewed for evidence of primary wound events such as SSIs, hematoma, and seroma formation, skin flap necrosis, and mesh removal. Hernia recurrence, seroma, hematoma and flap necrosis were based on clinical symptoms and physical exam findings observed during follow-up appointments. SSI were not necessarily culture proven but were determined based on clinical findings of surrounding incisional cellulitis and leukocytosis. This information was stored in a secure database. Data analysis utilized Microsoft Excel (Redmond, WA) and SPSS statistical software version 18.0 (IBM). Variables were stratified by wound closure technique. Chisquared analysis with Fisher’s exact test was applied to categorical variables. Variables that demonstrated statistically significant differences in univariate analysis were
123
Hernia Table 2 Distribution of surgical site infection based on wound closure Surgical site infection by location Superficial Deep Organ space
Wound closure
Table 3 Surgical outcomes based on wound closure Surgical outcomes: based on wound closure
Primary (n = 32)
PVC (n = 29)
Chisquared
Primary, n
PVC, n
Hematoma (n = 2)
2
0
0.49
7
4
Seroma (n = 6)
3
3
1.00
1
Skin flap necrosis (n = 5)
2
3
0.67
0
Surgical site infection (SSI) (n = 22)
17
5
0.01
Mesh removal (n = 3)
3
0
0.24
Hernia recurrence (n = 8)
7
1
0.05
6 4
further analyzed using multivariate regression analysis for their contribution to post-operative complications. All tests were two-tailed, and a p value \0.05 was determined to be statistically significant.
Bold values indicate statistically significance
For PVC that distribution was four superficial, one deep and no organ space involvement (Table 2). Results Between May 2008 and July 2011, there were 61 patients who met inclusion criteria. The mean age was 54 and 60 % were women. Fifty-seven percent of all patients underwent component separation. Thirty-two patients had PC and 29 patients had PVC, as previously described. The average hernia defect size was 343 cm2 for primary wound closure and 375 cm2 for PVC. There was no statistically significant difference between groups. All prior medical and surgical history was similar between both groups with a few exceptions (Table 1). There was no difference in average wound classification per wound closure group. The PVC closure group had a higher percentage of prior intra-abdominal infections defined by culture positive fluid collections that required either percutaneous intervention or laparotomy for drainage. Finally, there was a higher portion of patients who underwent PVC that had a BMI [30. The mean length of (LOS) was 10 days for PC and 7 days for PVC. However, the difference between these groups was not statistically significant. The mean length of follow-up (LOF) was 167 days for both groups. Average LOF was 334 days and 240 days, respectively, for PC and PVC groups. Once again, these differences were not statistically significant. Wound closure type did affect hernia recurrence. Seven hernias recurred for PC and 1 for PVC (p \ 0.05). The hernia recurrence for PVC occurred at 145 days while the average recurrence for PC occurred after 159 days. Overall, PVC had a lower recurrence rate of 25 vs. 3 %. The type of wound closure had a profound effect on the rate and type of SSI. These infections were further categorized into superficial, deep, and organ space infection based on intervention required for treatment (antibiotics, opening of the wound, laparotomy, or percutaneous drainage procedure). The distribution of SSI for PC was seven superficial, six deep and four organ space infections.
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Discussion This study was designed to evaluate the potential benefit of applying NPT to closed wounds in patients undergoing AWR to help decrease the rate of wound events. There was an association between PVC and decreased SSI and recurrent hernias. The distribution of the wound infections was different between the two groups with the PC group having more deep tissue and organ space infections than the PVC group. The numbers are too small to make any real conclusions from this data. At this point it is unclear the mechanism behind the decreased SSI rate. Many theories exist including decreased post-operative sheering of skin flaps with NPT, faster stimulation of growth factors to the wound, increased wound strength, and increased perfusion to local tissues, however, we have no definitive evidence to show causality [21, 22]. This study was not designed to look at financial implications of using NPT on closed wounds in today’s medical–economic climate, but it is difficult not to comment about it. Applying a VAC increases the cost of any operation. The cost of the original dressing as well as the rental of the machine for the week that it was left in place is obviously a deterrent. With our data showing a decreased SSI rate this could potentially save the hospital thousands of dollars during the patient’s hospital stay and global reimbursement period. Also, with a decreased recurrent hernia rate in the future or in areas with a single payer model potential long-term cost savings are possible as well. Obviously a dedicated financial study would be needed to draw any conclusions regarding the cost benefit of NPT use [20]. Decreased LOS is also a potential cost benefit. This study showed an overall decreased length of stay in the PVC group, however, this did not reach statistical significance. A larger study might have the power to show this.
Hernia
Hernia recurrence is a risk after AWR. Recurrence rates up to 32 % have been reported [6]. In this study, PVC was associated with a substantial reduction in recurrences but a limitation of our study was a short time to follow-up. (Table 3). Despite this limitation, the results of this study warrant consideration and further continued investigation. The use of NPT on primarily closed wounds is a relatively new application of the technology. There is a growing body of literature that suggests that PVC is a beneficial adjunct when closing abdominal wounds prone to complication [14, 16]. Recently Conde-Green, et al. published a case control study that evaluated the effect of NPT has on primarily closed abdominal wall reconstructed with biologic mesh [21]. They found significant reduction in wound complications and recurrence rate. This work, collected during a similar time frame at two different institutions concurs with our own work that associates NPT with improved wound outcomes. Although our population differs by overall complication rate, the benefit conferred by PVC, especially for SSI, is conserved. Furthermore our cohort, at high risk for complication, experienced a greater overall reduction in complication. Perhaps PVC is a particularly useful adjunct in those patients at highest risk. While Pauli et al. published a prospective study that was retrospectively reviewed indicating that prophylactic NPT in the setting of a closed surgical incision did not reduce the incidence of SSI, there were several limitations to their study [22]. The study was not randomized, and the surgical technique used over the span of the study was changed. Despite the conflicting outcomes noted in the Pauli et al. study, the results of this study show a reduction in wound morbidity and warrant attention.
Conclusion Hernia recurrence, SSI and potential reoperation remain challenging post-operative complications after AWR. Our data suggest that the use of NPT, applied to primarily closed wounds, is associated with decreased incidence of these morbidities. In this study, there was a reduction in both the overall rate of SSI and hernia recurrence with PVC when compared to the PC group. These results demonstrate a potential advantage for adjunctive NPT use in patients undergoing AWR, especially those that are high risk for a wound event. This was a small retrospective review, and therefore care must be taken when drawing conclusions from results and such a small data set. Although technique, materials, and population demographics were matched between study groups, confounding factors may be present and not controlled for. Selection bias may also influence results as the groups were not randomized and is a limitation of the study. A larger prospective randomized blinded study may
be warranted based on these preliminary results. There continues to be a paucity of literature discussing the use of NPT for closed abdominal incisions after AWR. This study suggests that NPT decreases SSI and hernia recurrence after AWR when compared to conventional dressing. Although, there are limitations to the study, the results warrant consideration and further continued investigation. Conflict of interest AG declares no conflict of interest. AM declares no conflict of interest. EB declares no conflict of interest. AA declares no conflict of interest. OG declares no conflict of interest. MM declares no conflict of interest. TE declares no conflict of interest. CT declares no conflict of interest.
References 1. Korenkov M, Paul A, Sauerland S, Neugebauer E, Arndt M, Chevrel JP, Corcione F, Fingerhut A, Flament JB, Kux M, Matzinger A, Myrvold HE, Rath AM, Simmermacher RK (2001) Classification and surgical treatment of incisional hernia. Results of an experts’ meeting. Langenbecks Arch Surg 386:65–73 2. Bachman SL, Ramaswamy A, Ramshaw BJ (2009) Early results of midline hernia repair using a minimally invasive component separation technique. Am Surg 75:572–577 (discussion 577–578) 3. Barbaros U, Asoglu O, Seven R, Erbil Y, Dinccag A, Deveci U, Ozarmagan S, Mercan S (2007) The comparison of laparoscopic and open ventral hernia repairs: a prospective randomized study. Hernia 11:51–56 4. Breuing K, Butler CE, Ferzoco S, Franz M, Hultman CS, Kilbridge JF, Rosen M, Silverman RP, Vargo D (2010) Incisional ventral hernias: review of the literature and recommendations regarding the grading and technique of repair. Surgery 148:544–558 5. Candage R, Jones K, Luchette FA, Sinacore JM, Vandevender D, Reed RL 2nd (2008) Use of human acellular dermal matrix for hernia repair: friend or foe? Surgery 144:703–709 (discussion 709–711) 6. de Vries Reilingh TS, van Goor H, Rosman C, Bemelmans MH, de Jong D, van Nieuwenhoven EJ, van Engeland MI, Bleichrodt RP (2003) ‘‘Components separation technique’’ for the repair of large abdominal wall hernias. J Am Coll Surg 196:32–37 7. Diaz JJ, Jr, Guy J, Berkes MB, Guillamondegui O, Miller RS (2006) Acellular dermal allograft for ventral hernia repair in the compromised surgical field. Am Surg 72:1181–1187 (discussion 1187–1188) 8. Eriksen JR, Gogenur I, Rosenberg J (2007) Choice of mesh for laparoscopic ventral hernia repair. Hernia 11:481–492 9. Goodney PP, Birkmeyer CM, Birkmeyer JD (2002) Short-term outcomes of laparoscopic and open ventral hernia repair: a metaanalysis. Arch Surg 137:1161–1165 10. Ko JH, Wang EC, Salvay DM, Paul BC, Dumanian GA (2009) Abdominal wall reconstruction: lessons learned from 200 ‘‘components separation’’ procedures. Arch Surg 144:1047–1055 11. Larson GM (2000) Ventral hernia repair by the laparoscopic approach. Surg Clin North Am 80:1329–1340 12. Lowham AS, Filipi CJ, Fitzgibbons RJ Jr, Stoppa R, Wantz GE, Felix EL, Crafton WB (1997) Mechanisms of hernia recurrence after preperitoneal mesh repair. Traditional and laparoscopic. Ann Surg 225:422–431
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Hernia 13. Meeker J, Weinhold P, Dahners L (2011) Negative pressure therapy on primarily closed wounds improves wound healing parameters at 3 days in a porcine model. J Orthop Trauma 25:756–761 14. Pachowsky M, Gusinde J, Klein A, Lehrl S, Schulz-Drost S, Schlechtweg P, Pauser J, Gelse K, Brem MH (2012) Negative pressure wound therapy to prevent seromas and treat surgical incisions after total hip arthroplasty. Int Orthop 36:719–722 15. Tocco MP, Costantino A, Ballardini M, D’Andrea C, Masala M, Merico E, Mosillo L, Sordini P (2009) Improved results of the vacuum assisted closure and nitinol clips sternal closure after postoperative deep sternal wound infection. Eur J Cardiothorac Surg 35:833–838 16. Blackham AU, Farrah JP, McCoy TP, Schmidt BS, Shen P (2013) Prevention of surgical site infections in high-risk patients with laparotomy incisions using negative-pressure therapy. Am J Surg 205:647–654 17. Lee SY, Niikura T, Miwa M, Sakai Y, Oe K, Fukazawa T, Kawakami Y, Kurosaka M (2011) Negative pressure wound therapy for the treatment of infected wounds with exposed knee joint after patellar fracture. Orthopedics 34:211
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18. Satterwhite TS, Miri S, Chung C, Spain D, Lorenz HP, Lee GK (2012) Outcomes of complex abdominal herniorrhaphy: experience with 106 cases. Ann Plast Surg 68:382–388 19. Ramirez OM, Ruas E, Dellon AL (1990) ‘‘Components separation’’ method for closure of abdominal-wall defects: an anatomic and clinical study. Plast Reconstr Surg 86:519–526 20. Boltz MM, Hollenbeak CS, Julian KG, Ortenzi G, Dillon PW (2011) Hospital costs associated with surgical site infections in general and vascular surgery patients. Surgery 150:934–942 21. Conde-Green A, Chung TL, Holton LH 3rd, Hui-Chou HG, Zhu Y, Wang H, Zahiri H, Singh DP (2013) Incisional negativepressure wound therapy versus conventional dressings following abdominal wall reconstruction: A comparative study. Ann Plast Surg 71:394–397 22. Pauli EM, Krpata DM, Novitsky YW, Rosen MJ (2013) Negative pressure therapy for high-risk abdominal wall reconstruction incisions. Surg Infect 14:270–274
ORIGINAL ARTICLE
Positive outcomes with negative pressure therapy over primarily closed large abdominal wall reconstruction reduces surgical site infection rates A. Gassman • A. Mehta • E. Bucholdz • A. Abthani • O. Guerra • M. M. Maclin Jr T. Esposito • C. Thomas
•
Received: 1 August 2013 / Accepted: 12 September 2014 Ó Springer-Verlag France 2014
Abstract Purpose There is a significant morbidity associated with abdominal wall reconstruction (AWR) with a need for overall improvement during the post-operative management. Scientific literature has proven the use of negative pressure therapy (NPT) in wound healing for orthopedic and cardiac surgery with limited data present on its role in AWR. The goal of this study was to examine whether primary wound events were different between patients who had primary closure with NPT versus patients who only had primary closure after AWR. Methods This retrospective study examined the rate of post-operative complications in all open-complex AWR that were done in a similar fashion between May 2008 and July 2011 at two large university teaching hospitals. Wound closure was stringent upon attending surgeon preference without randomization. Results There were a total of 61 patients who met inclusion criteria with an average age of 54 and 60 % were women.
A. Gassman Division of Plastic and Reconstructive Surgery, UCLA Department of Surgery, David Geffen School of Medicine, Los Angeles, CA, USA A. Mehta (&) E. Bucholdz T. Esposito C. Thomas Department of Surgery, Loyola University Medical Center, Maywood, IL, USA e-mail: [email protected] A. Abthani Department of Surgery, Northeast Ohio Medical University, Rootstown, OH, USA O. Guerra M. M. Maclin Jr Department of Surgery, Missouri Baptist Medical Center, St. Louis, MO, USA
Thirty-two patients had primary closure and 29 patients had primary closure with NPT. The mean length of follow-up was 167 days for both groups. The type of wound closure had an effect on the rate of hernia recurrence and surgical site infections. The application of NPT leads to lower hernia recurrence rate of 25 versus 3 % and the type of wound closure had a profound effect on the rate and type of SSI. Conclusions The data presented in this study demonstrates a potential advantage for adjunctive NPT in patients undergoing AWR. There is an associated decreased incidence in the overall rate of SSI and hernia recurrence with the use of NPT in those patients undergoing AWR. These results show an advantage for adjunctive NPT. Keywords Negative pressure therapy Abdominal wall reconstruction
Introduction Incisional hernia remains a common complication after abdominal surgery, and no consensus exists on optimal treatment. Many operative techniques for herniorrhaphy are available. These include simple primary suture repair, prosthetic implantation, or autologous tissue closure, and most options can be performed by either open or laparoscopic approaches [1–12]. Local wound complication rates are high for complex abdominal wall reconstruction (AWR). Despite a myriad of treatment options, there still exists significant morbidity associated with incisional hernia repair such as surgical site infections (SSI), seromas, hematomas, hernia recurrence and mesh complications often requiring removal. There is an obvious necessity for improvement in the post-operative management to alleviate the morbidity associated with these repairs.
123
Hernia
Negative pressure therapy (NPT) has become an accepted intervention in wound healing with scientific literature supporting its efficacy in a variety of wound types [13]. It has been used in the field of orthopedic surgery to decrease hematoma formation, increase the mechanical strength of dermal wound closure, and improve the clinical appearance of post-operative scars [14]. Additionally, in cardiac surgery, the use of NPT after sternotomy has been shown to decrease wound infections [15]. One report suggested that the use of NPT decreased SSI in patients undergoing laparotomy for oncologic resection [16]. The advantages of NPT are multifold with respect to increased bacterial clearance, tissue perfusion rate, and promotion of granulation tissue formation in the wound bed [17]. The current standard for incisional hernia repair is a reinforced repair. To alleviate tension across fascia, mesh derived from either synthetic or biologic material is placed to span or buttress the hernia defect and recreate structural integrity. Despite significant advantages, permanent synthetic mesh has drawbacks including: increased risk for visceral adhesions to the repair site, erosion into the bowel, enterocutaneous fistulae and/or bowel obstruction, extrusion of repair material, infection, seroma, and wound dehiscence [4]. Component separation of abdominal wall musculature to close fascial defect has also been described. However, re-herniation rates have been described up to 32 % after unreinforced, myofascial advancement flaps. Skin flap necrosis, seroma formation, and wound infection have all been reported as complications after this method of abdominal wall reconstruction. Although mesh reinforcement of component separation repairs reduces recurrence rates, complications such as hematoma and infection have been reported with rates of 16.7–63 % [10, 18]. Large and complex abdominal wall defects are requiring surgeons to push the limits of repairs. AWR with reinforcement is an excellent choice for the large midline defect, however, it incurs at the large risk of wound events. Initial closure of abdominal wounds requires a great deal of flexibility. There is limited data describing the use of NPT as an adjunct to primarily closed AWRs. To verify this growing body of literature, we compared 7 days of NPT to closed incisions versus standard dressings after AWR. We tested whether primary wound events such as SSIs, hematoma and seroma formation, skin flap necrosis and mesh removal were different between patients who had primary vacuum closure (PVC-primary closure with NPT) versus patients who only had primary closure (PC).
Methods This retrospective institutional review board (IRB) approved study examined the rate of post-operative
123
Fig. 1 a Primary closure of midline incision after AWR with staples. b Application of NPT over midline incision after closure
complications in all open, complex AWR performed between May 2008 and July 2011 at two large university teaching hospitals. IRB approval was obtained at each hospital. Two different surgeons performed the AWR where one surgeon’s practice was at Loyola Medical Center in Maywood, IL, and the two other performed the operation at Missouri Baptist Medical Center in Saint Louis, MO. Patient selection The hospital operative logs were queried by CPT code to identify a retrospective cohort of patients who underwent complex AWR requiring the use of biologic mesh [200 cm2. All patients underwent AWR with PC of the skin and operations were performed under the direction of a single attending surgeon at his respective hospital. Patients were selected to undergo PC or PVC based on surgeon preference. The cases in this series were clean. Information on demographics, co-morbid diseases, and medication use was also collected.
Hernia
Surgical technique All incisional hernias were repaired with an open technique. Similarity in operative methods was compared through chart review of each surgeon’s operative reports. After thromboembolism prophylaxis and perioperative antibiotics administration, each patient was administered general anesthesia. After lysing intra-abdominal adhesions when necessary, all patients underwent intraperitoneal underlay with Strattice (Lifecell/KCI) porcine acellular dermal matrix secondary to surgeon preference. The biologic mesh was sized to achieve at least 5 cm of underlay circumferentially around the fascial defect. Interrupted transfascial absorbable 0 or 1 PDS sutures were used to circumferentially fix the mesh as a wide underlay by elevating wide skin flaps. All patients had a variant of fascial closure. Fascia was completely re-approximated in the midline and edges were approximated over the mesh. In the cases where fascial closure was not possible, a component separation was performed as described by Ramirez et al. to aid in further fascial closure [19]. Partial fascial closure over the mesh was done when there was an increase in abdominal pressure as manifested by increased ventilator airway pressures ([32 mmHg). As each abdominal wall had varying level of compliance secondary to lateral muscular retraction, and reconstruction technique was similar, mesh size was used as a relative measure to compare defect size. Closed suction drainage (3–5 Jackson-Pratt or Blake drains) was placed in all cases. Drains were placed medially between the fascia and mesh as well as laterally in each gutter underneath the skin flaps. Drains remained in place until fluid output was less than or equal to 30 ml per day. They were typically removed in clinic after hospital discharge. All prior scar tissue, hernia sac, previously placed mesh and devitalized tissue was removed prior to closure. PC or PVC methods of skin closure were employed after copious irrigation and hemostasis. Wounds closure method was based on attending surgeon preference, and no randomization was employed. Primarily closed wounds had the skin edges approximated with stainless steel staples and dry occlusive dressings. The PVC patients received the same, stapled, primary skin closure with topical NPT as an overlay adjunct. These patients had a KCI commercial vacuum-assisted closure (VAC) device applied in a linear strip along the length of their closed incision (Fig. 1a, b). Care was taken to protect the underlying skin with either a layer of Adaptic (Johnson & Johnson) non-adhering dressing or perforated silastic sheets. The black polyurethane foam was cut as the same width as the protective skin dressing. Once complete adhesion and seal were certain, the wounds then received 7 days of continuous 125 mmHg
Table 1 Patient population similarities between both groups Population characteristics
Wound closure
Risk factor
Primary (n = 32)
PVC (n = 29)
Chisquared
Patient derived risk Gender (female)
17
21
0.118
Obesity (BMI [30) Current smoker
10 5
21 3
0.002 0.708
HTN
18
10
0.129
CAD
8
3
0.302
PVD
1
1
1.000
DM
12
8
0.585
Immunosuppression
2
1
1.000
13
11
0.797
Prior surgery Prior hernia repair with mesh Prior intra-abdominal infection
9
20
0.002
Ostomy prior or present at the time of surgery
14
7
0.774
Intra-abdominal infection at the time of surgery
4
3
0.538
Prior abdominoplasty
2
1
1.000
Operative details Component separation
16
19
0.306
Average CDC wound classification (1–4)
2.53 n
2.62 n
0.56 (SD)
Bold values indicate statistically significance HTN hypertension, CAD coronary artery disease, PVD peripheral vascular disease, DM diabetes mellitus, CDC center for disease control and prevention
NPT with the VAC device. At 7 days, the NPT was removed. PC wounds were otherwise followed in the same fashion as in the PVC group. Data collection The study population’s electronic medical records were reviewed for evidence of primary wound events such as SSIs, hematoma, and seroma formation, skin flap necrosis, and mesh removal. Hernia recurrence, seroma, hematoma and flap necrosis were based on clinical symptoms and physical exam findings observed during follow-up appointments. SSI were not necessarily culture proven but were determined based on clinical findings of surrounding incisional cellulitis and leukocytosis. This information was stored in a secure database. Data analysis utilized Microsoft Excel (Redmond, WA) and SPSS statistical software version 18.0 (IBM). Variables were stratified by wound closure technique. Chisquared analysis with Fisher’s exact test was applied to categorical variables. Variables that demonstrated statistically significant differences in univariate analysis were
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Hernia Table 2 Distribution of surgical site infection based on wound closure Surgical site infection by location Superficial Deep Organ space
Wound closure
Table 3 Surgical outcomes based on wound closure Surgical outcomes: based on wound closure
Primary (n = 32)
PVC (n = 29)
Chisquared
Primary, n
PVC, n
Hematoma (n = 2)
2
0
0.49
7
4
Seroma (n = 6)
3
3
1.00
1
Skin flap necrosis (n = 5)
2
3
0.67
0
Surgical site infection (SSI) (n = 22)
17
5
0.01
Mesh removal (n = 3)
3
0
0.24
Hernia recurrence (n = 8)
7
1
0.05
6 4
further analyzed using multivariate regression analysis for their contribution to post-operative complications. All tests were two-tailed, and a p value \0.05 was determined to be statistically significant.
Bold values indicate statistically significance
For PVC that distribution was four superficial, one deep and no organ space involvement (Table 2). Results Between May 2008 and July 2011, there were 61 patients who met inclusion criteria. The mean age was 54 and 60 % were women. Fifty-seven percent of all patients underwent component separation. Thirty-two patients had PC and 29 patients had PVC, as previously described. The average hernia defect size was 343 cm2 for primary wound closure and 375 cm2 for PVC. There was no statistically significant difference between groups. All prior medical and surgical history was similar between both groups with a few exceptions (Table 1). There was no difference in average wound classification per wound closure group. The PVC closure group had a higher percentage of prior intra-abdominal infections defined by culture positive fluid collections that required either percutaneous intervention or laparotomy for drainage. Finally, there was a higher portion of patients who underwent PVC that had a BMI [30. The mean length of (LOS) was 10 days for PC and 7 days for PVC. However, the difference between these groups was not statistically significant. The mean length of follow-up (LOF) was 167 days for both groups. Average LOF was 334 days and 240 days, respectively, for PC and PVC groups. Once again, these differences were not statistically significant. Wound closure type did affect hernia recurrence. Seven hernias recurred for PC and 1 for PVC (p \ 0.05). The hernia recurrence for PVC occurred at 145 days while the average recurrence for PC occurred after 159 days. Overall, PVC had a lower recurrence rate of 25 vs. 3 %. The type of wound closure had a profound effect on the rate and type of SSI. These infections were further categorized into superficial, deep, and organ space infection based on intervention required for treatment (antibiotics, opening of the wound, laparotomy, or percutaneous drainage procedure). The distribution of SSI for PC was seven superficial, six deep and four organ space infections.
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Discussion This study was designed to evaluate the potential benefit of applying NPT to closed wounds in patients undergoing AWR to help decrease the rate of wound events. There was an association between PVC and decreased SSI and recurrent hernias. The distribution of the wound infections was different between the two groups with the PC group having more deep tissue and organ space infections than the PVC group. The numbers are too small to make any real conclusions from this data. At this point it is unclear the mechanism behind the decreased SSI rate. Many theories exist including decreased post-operative sheering of skin flaps with NPT, faster stimulation of growth factors to the wound, increased wound strength, and increased perfusion to local tissues, however, we have no definitive evidence to show causality [21, 22]. This study was not designed to look at financial implications of using NPT on closed wounds in today’s medical–economic climate, but it is difficult not to comment about it. Applying a VAC increases the cost of any operation. The cost of the original dressing as well as the rental of the machine for the week that it was left in place is obviously a deterrent. With our data showing a decreased SSI rate this could potentially save the hospital thousands of dollars during the patient’s hospital stay and global reimbursement period. Also, with a decreased recurrent hernia rate in the future or in areas with a single payer model potential long-term cost savings are possible as well. Obviously a dedicated financial study would be needed to draw any conclusions regarding the cost benefit of NPT use [20]. Decreased LOS is also a potential cost benefit. This study showed an overall decreased length of stay in the PVC group, however, this did not reach statistical significance. A larger study might have the power to show this.
Hernia
Hernia recurrence is a risk after AWR. Recurrence rates up to 32 % have been reported [6]. In this study, PVC was associated with a substantial reduction in recurrences but a limitation of our study was a short time to follow-up. (Table 3). Despite this limitation, the results of this study warrant consideration and further continued investigation. The use of NPT on primarily closed wounds is a relatively new application of the technology. There is a growing body of literature that suggests that PVC is a beneficial adjunct when closing abdominal wounds prone to complication [14, 16]. Recently Conde-Green, et al. published a case control study that evaluated the effect of NPT has on primarily closed abdominal wall reconstructed with biologic mesh [21]. They found significant reduction in wound complications and recurrence rate. This work, collected during a similar time frame at two different institutions concurs with our own work that associates NPT with improved wound outcomes. Although our population differs by overall complication rate, the benefit conferred by PVC, especially for SSI, is conserved. Furthermore our cohort, at high risk for complication, experienced a greater overall reduction in complication. Perhaps PVC is a particularly useful adjunct in those patients at highest risk. While Pauli et al. published a prospective study that was retrospectively reviewed indicating that prophylactic NPT in the setting of a closed surgical incision did not reduce the incidence of SSI, there were several limitations to their study [22]. The study was not randomized, and the surgical technique used over the span of the study was changed. Despite the conflicting outcomes noted in the Pauli et al. study, the results of this study show a reduction in wound morbidity and warrant attention.
Conclusion Hernia recurrence, SSI and potential reoperation remain challenging post-operative complications after AWR. Our data suggest that the use of NPT, applied to primarily closed wounds, is associated with decreased incidence of these morbidities. In this study, there was a reduction in both the overall rate of SSI and hernia recurrence with PVC when compared to the PC group. These results demonstrate a potential advantage for adjunctive NPT use in patients undergoing AWR, especially those that are high risk for a wound event. This was a small retrospective review, and therefore care must be taken when drawing conclusions from results and such a small data set. Although technique, materials, and population demographics were matched between study groups, confounding factors may be present and not controlled for. Selection bias may also influence results as the groups were not randomized and is a limitation of the study. A larger prospective randomized blinded study may
be warranted based on these preliminary results. There continues to be a paucity of literature discussing the use of NPT for closed abdominal incisions after AWR. This study suggests that NPT decreases SSI and hernia recurrence after AWR when compared to conventional dressing. Although, there are limitations to the study, the results warrant consideration and further continued investigation. Conflict of interest AG declares no conflict of interest. AM declares no conflict of interest. EB declares no conflict of interest. AA declares no conflict of interest. OG declares no conflict of interest. MM declares no conflict of interest. TE declares no conflict of interest. CT declares no conflict of interest.
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