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Vascular Prosthesis Infections
Symposium on Surgical Infections
Vascular Prosthesis Infections
William J. Fry, M.D.*
The grave implications of wound infection associated with vascular reconstructive surgery and its necessary reliance on plastic prosthetic materials pose frightful problems in healing and often result in the loss of an extremity or a life. The reported incidence of graft infection at the University of Michigan Medical Center has been 1.34 per cent. 3 This is in accordance with other reports which vary from 1 to 6 per cent. 1, 2, 4-6, 8 In a recent report from the Henry Ford Hospital the incidence of infections using prosthetic grafts was 1.5 per cent. 9 1t would appear that any infection is unacceptable; however, certainly 1.3 to 1.5 per cent would seem to be the recognized range of infection. Because of the severe complications following infection, anything above 2 per cent would seem to be unacceptable. The review of this topic seems timely, as there has been change in the bacterial flora cultured from infected vascular prostheses at the University of Michigan Medical Center. In an earlier report from this institution the culture results from the infected prostheses showed a predominance of Staphylococcus aureus, this having been the primary organism cultured in two thirds of the cases, and gram-negative organisms representing the organisms cultured in the remaining third. Since that report we have instituted a program of prophylactic antibiotics utilizing oxacillin routinely the night before operation, on the day of operation, and for two days after operation in an attempt to cut down the incidence of staphylococcal infection. Recent review of culture results demonstrates that two thirds of the cultured organisms from infected grafts now are of the gram-negative variety and one-third are of the staphylococcal type organism. It would appear that the rationale of prophylactic antibiotics has been helpful; however, it has resulted in a predominance of gram-negative organisms involving the infected prosthesis. It is important to note that the total incidence of infection of vascular prostheses has not increased since our initial report in 1967. The manifestations of prosthetic infection are summarized in Figures 1, 2, and 3. The common manifestations are listed as follows: false aneurysm, hemorrhage, thrombosis of the prosthesis, localized abscess, ·Professor and Head, Section of General Surgery, University of Michigan Medical Center, Ann Arbor, Michigan Surgical Clinics of North America- Vol. 52, No.6, December 1972
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FRY
Figure 1. Manifestations of an infected arterial prosthesis. (1) False aneurysm; (2) hemorrhage; (3) thrombosis of prosthesis; (4) abscess; (5) chrorucdraining sinus.
Figure 2. Manifestations of an infected arterial prosthesis. (6) Septic emboli; (7) propagation of infection to contralateral limb.
Figure 3. Manifestations of an infected arterial prosthesis: septicemia and metastatic abscess.
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chronic draining sinus, peripheral septic emboli, propagation of infection to the contralateral limb, septicemia, and metastatic abscess formation.
SOURCE OF INFECTION Because of the recent increase in gram-negative infections we have searched for a source of this contamination. It seems unlikely that such organisms would be a contaminant from the surgical instruments or the personnel within the operating room. It has been postulated that the source of the gram-negative organisms is the patient himself and therefore a search was undertaken to discover this area of contamination. The most common procedure with which infection is associated is the aortofemoral bypass. There seems to be little question that the skin of the inguinal region is the source of contamination. This we believe ac~ counts for our early high incidence of staphylococcal infections. The inability to prepare the inguinal skin adequately, the necessity to shave this area, causing microlacerations and subsequent harboring of organisms, is obvious. Certainly the length of time of exposure in the groin plays a part in the contamination of this area when an aortofemoral bypass using a synthetic prosthesis is performed. The relative low incidence of infection seen in aorto-iliac reconstructive procedures would give credence to the thought that excellent preparation of the abdominal skin and the use of plastic protective drapes prevents the contamination of skin organisms within the abdominal cavity. At the time of aortic resection the small bowel is dislocated from the peritoneal cavity and packed into a plastic bowel bag. During the course of the procedure there is a small amount, usually 50 to 100 ml., of fluid extruded by the bowel into this plastic container. The material recovered from the bowel bag at the conclusion of the reconstructive procedure is cultured and has almost routinely grown out typical enteric gram-negative organisms. It would appear that the relative deprivation of blood supply by dislocation of the small bowel out of the abdomen plus the cinching of the bag around the root of the mesentery has contributed to a relative ischemia of the small bowel. This in turn has allowed diapedesis of enteric organisms through the bowel wall onto the peritoneal surface and these contaminate the fluid that collects in the bowel bag during the procedure. If this material then is inadvertently introduced into the area of the graft the cycle is complete and the prosthesis is contaminated. While the above cultures are present and a mechanism for contamination with gram-negative organisms has been delineated, it would appear that other sources of contamination may also be present. Certainly any deprivation of blood supply of the colon or inadvertent break in the continuity of the bowel wall during dissection will readily contaminate the peritoneal and retroperitioneal structures. It seems prudent that one exercise extreme caution during the operative procedure to prevent any break in the continuity of the bowel wall or deprivation of its blood supply. The rationale of carefully controlled prophylactic antibiotics seems to us valid. While it is impossible to run an accurate prospective study, we
VASCULAR PROSTHESIS INFECTIONS
1423
have seen a reversal in the character of the prosthetic infections at this institution with the use of oxacillin. Now that another potential source of contamination has been delineated the addition of a second antibiotic for prophylaxis is in order. We have recently embarked on the use of both kanamycin and oxacillin as a prophylaxis during vascular reconstructive procedures. Administration of both drugs is started the evening before operation, and is continued during the operation and for the first 2 postoperative days. While the results of this are not available at the present time, it would seem prudent considering well delineated sources of contamination. Animal work already reported confirms the rationale of prophylactic antibiotics when arterial prosthetic materials are used. 7
PRINCIPLES OF MANAGEMENT The complete management of an infected arterial prosthesis requires that two objectives be met. The first objective is to completely remove the infected portion of the arterial prosthesis. The second is restoration of blood flow by an alternate bypass route. We would certainly agree with Dr. Szilagyi and his group9 that aggressive surgical therapy is the method of choice rather than procrastination and the vain hope that things will spontaneously heal. When the latter tack is taken the usual result is an exsanguinating hemorrhage as the suture line becomes involved by the infection. There are several authors who would not agree with the removal of the infected prosthesis. The use of topical antibiotics with catheter instillation has been advocated. 5 • 6. 8 It is difficult on review of these reports to delineate any concrete figures regarding the success of such therapy. Generally our efforts at conservative therapy of infected arterial prostheses by irrigation with antibiotics have met with disaster. In aortofemoral grafts one limb or a portion of one limb may be the only area harboring infection. It is important to point out that the removal of the entire graft is not necessary in such a circumstance. The surgical management of the infected graft certainly taxes the surgeon as much as any procedure carried out in the operating theater. A debilitated patient with marked sepsis, often with accompanying hemorrhage, must face a long and involved procedure to remove the arterial prosthesis, followed by institution of an extra-anatomical bypass to restore blood flow. On many occasions this procedure can be staged, with several days intervening between operations; however, in the case of hemorrhage this will not be feasible. If the prosthesis is infected but there is no hemorrhage from suture line involvement, one may perform the staged procedure of instituting an extra-anatOInical bypass with a hiatus of several days before the prosthesis is removed. The judicious and continued use of the proper antibiotics during this period of time is mandatory to prevent infection of the new prosthesis by blood-borne bacteria. The various types of extra-anatOInical bypasses have been well outlined by many authors, including ourselves, in past publications. The proper route of extra-anatoInical bypass should be chosen care-
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WILLIAM
J.
FRY
fully and the use of autogenous tissue should be emphasized whenever possible. The autogenous saphenous vein for the extra-anatomical bypass, while not immune from infection, certainly is a safer graft to use in that it is viable tissue.
CONCLUSION During the past 5 years, with the institution of prophylactic antibiotics during the course of arterial reconstructive operations there has been a change in the organisms causing prosthetic infections. We believe this is due to the judicious use of oxacillin as a prophylactic antibiotic agent. Gram-negatives organisms have been found in the bag holding the intestines during aortic resection. We have added to the prophylactic antibiotic therapy the drug kanamycin in an effort to suppress the chance for prosthetic contamination with the gram-negative organism.
REFERENCES 1. Barker, W. F.: Peripheral Arterial Disease. Philadelphia, W. B. Saunders Co., 1966. 2. Diethrich, E. B., Noon, G. P., Liddicoat, J. E., and DeBakey, M. E.: Treatment of infected aortofemoral arterial prosthesis. Surgery, 68:1044,1970. 3. Fry, w. J., and Lindenauer, S. M.: Infection complicating the use of plastic arterial implants. Arch. Surg., 94:600, 1967. . 4. Healey, S. J., Wheeler, B., Crane, C., and Warren, R: Reconstructive operations for aortoiliac obliterative disease. New Eng. J. Med., 271:1386,1964. 5. Hoffert, P. W., Gensler, S., and Haimovici, H.: Infection complicating arterial grafts. Arch. Surg., 90:427, 1965. 6. Javid, H., Julian, O. C., Dye, W. S., and Hunter, J. A.: Complications of abdominal aortic grafts. Arch. Surg., 85:650, 1962. 7. Lindenauer, S. M., Fry, W. J., Schaub, G., and Wild, D.: The use of antibiotics in the prevention of vascular graft infections. Surgery, 62:487, 1967. 8. Smith, R F., and Szilagyi, D. E.: Healing complications with plastic arterial implants. Arch. Surg., 82: 14, 1961. 9. Szilagyi, D. E., Smith, R F., Elliott, J. P., and Vrandecic, M. P.: Infection in arterial reconstruction with synthetic grafts. Presented at the Annual Meeting of the American Surgical Association, San Francisco, California, April 26-28, 1972.
Department of Surgery Section of General Surgery University of Michigan Medical Center Ann Arbor, Michigan 48104
Vascular Prosthesis Infections
William J. Fry, M.D.*
The grave implications of wound infection associated with vascular reconstructive surgery and its necessary reliance on plastic prosthetic materials pose frightful problems in healing and often result in the loss of an extremity or a life. The reported incidence of graft infection at the University of Michigan Medical Center has been 1.34 per cent. 3 This is in accordance with other reports which vary from 1 to 6 per cent. 1, 2, 4-6, 8 In a recent report from the Henry Ford Hospital the incidence of infections using prosthetic grafts was 1.5 per cent. 9 1t would appear that any infection is unacceptable; however, certainly 1.3 to 1.5 per cent would seem to be the recognized range of infection. Because of the severe complications following infection, anything above 2 per cent would seem to be unacceptable. The review of this topic seems timely, as there has been change in the bacterial flora cultured from infected vascular prostheses at the University of Michigan Medical Center. In an earlier report from this institution the culture results from the infected prostheses showed a predominance of Staphylococcus aureus, this having been the primary organism cultured in two thirds of the cases, and gram-negative organisms representing the organisms cultured in the remaining third. Since that report we have instituted a program of prophylactic antibiotics utilizing oxacillin routinely the night before operation, on the day of operation, and for two days after operation in an attempt to cut down the incidence of staphylococcal infection. Recent review of culture results demonstrates that two thirds of the cultured organisms from infected grafts now are of the gram-negative variety and one-third are of the staphylococcal type organism. It would appear that the rationale of prophylactic antibiotics has been helpful; however, it has resulted in a predominance of gram-negative organisms involving the infected prosthesis. It is important to note that the total incidence of infection of vascular prostheses has not increased since our initial report in 1967. The manifestations of prosthetic infection are summarized in Figures 1, 2, and 3. The common manifestations are listed as follows: false aneurysm, hemorrhage, thrombosis of the prosthesis, localized abscess, ·Professor and Head, Section of General Surgery, University of Michigan Medical Center, Ann Arbor, Michigan Surgical Clinics of North America- Vol. 52, No.6, December 1972
1419
1420
WILLJA,M
J.
FRY
Figure 1. Manifestations of an infected arterial prosthesis. (1) False aneurysm; (2) hemorrhage; (3) thrombosis of prosthesis; (4) abscess; (5) chrorucdraining sinus.
Figure 2. Manifestations of an infected arterial prosthesis. (6) Septic emboli; (7) propagation of infection to contralateral limb.
Figure 3. Manifestations of an infected arterial prosthesis: septicemia and metastatic abscess.
1421
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WILLIAM]. FRY
chronic draining sinus, peripheral septic emboli, propagation of infection to the contralateral limb, septicemia, and metastatic abscess formation.
SOURCE OF INFECTION Because of the recent increase in gram-negative infections we have searched for a source of this contamination. It seems unlikely that such organisms would be a contaminant from the surgical instruments or the personnel within the operating room. It has been postulated that the source of the gram-negative organisms is the patient himself and therefore a search was undertaken to discover this area of contamination. The most common procedure with which infection is associated is the aortofemoral bypass. There seems to be little question that the skin of the inguinal region is the source of contamination. This we believe ac~ counts for our early high incidence of staphylococcal infections. The inability to prepare the inguinal skin adequately, the necessity to shave this area, causing microlacerations and subsequent harboring of organisms, is obvious. Certainly the length of time of exposure in the groin plays a part in the contamination of this area when an aortofemoral bypass using a synthetic prosthesis is performed. The relative low incidence of infection seen in aorto-iliac reconstructive procedures would give credence to the thought that excellent preparation of the abdominal skin and the use of plastic protective drapes prevents the contamination of skin organisms within the abdominal cavity. At the time of aortic resection the small bowel is dislocated from the peritoneal cavity and packed into a plastic bowel bag. During the course of the procedure there is a small amount, usually 50 to 100 ml., of fluid extruded by the bowel into this plastic container. The material recovered from the bowel bag at the conclusion of the reconstructive procedure is cultured and has almost routinely grown out typical enteric gram-negative organisms. It would appear that the relative deprivation of blood supply by dislocation of the small bowel out of the abdomen plus the cinching of the bag around the root of the mesentery has contributed to a relative ischemia of the small bowel. This in turn has allowed diapedesis of enteric organisms through the bowel wall onto the peritoneal surface and these contaminate the fluid that collects in the bowel bag during the procedure. If this material then is inadvertently introduced into the area of the graft the cycle is complete and the prosthesis is contaminated. While the above cultures are present and a mechanism for contamination with gram-negative organisms has been delineated, it would appear that other sources of contamination may also be present. Certainly any deprivation of blood supply of the colon or inadvertent break in the continuity of the bowel wall during dissection will readily contaminate the peritoneal and retroperitioneal structures. It seems prudent that one exercise extreme caution during the operative procedure to prevent any break in the continuity of the bowel wall or deprivation of its blood supply. The rationale of carefully controlled prophylactic antibiotics seems to us valid. While it is impossible to run an accurate prospective study, we
VASCULAR PROSTHESIS INFECTIONS
1423
have seen a reversal in the character of the prosthetic infections at this institution with the use of oxacillin. Now that another potential source of contamination has been delineated the addition of a second antibiotic for prophylaxis is in order. We have recently embarked on the use of both kanamycin and oxacillin as a prophylaxis during vascular reconstructive procedures. Administration of both drugs is started the evening before operation, and is continued during the operation and for the first 2 postoperative days. While the results of this are not available at the present time, it would seem prudent considering well delineated sources of contamination. Animal work already reported confirms the rationale of prophylactic antibiotics when arterial prosthetic materials are used. 7
PRINCIPLES OF MANAGEMENT The complete management of an infected arterial prosthesis requires that two objectives be met. The first objective is to completely remove the infected portion of the arterial prosthesis. The second is restoration of blood flow by an alternate bypass route. We would certainly agree with Dr. Szilagyi and his group9 that aggressive surgical therapy is the method of choice rather than procrastination and the vain hope that things will spontaneously heal. When the latter tack is taken the usual result is an exsanguinating hemorrhage as the suture line becomes involved by the infection. There are several authors who would not agree with the removal of the infected prosthesis. The use of topical antibiotics with catheter instillation has been advocated. 5 • 6. 8 It is difficult on review of these reports to delineate any concrete figures regarding the success of such therapy. Generally our efforts at conservative therapy of infected arterial prostheses by irrigation with antibiotics have met with disaster. In aortofemoral grafts one limb or a portion of one limb may be the only area harboring infection. It is important to point out that the removal of the entire graft is not necessary in such a circumstance. The surgical management of the infected graft certainly taxes the surgeon as much as any procedure carried out in the operating theater. A debilitated patient with marked sepsis, often with accompanying hemorrhage, must face a long and involved procedure to remove the arterial prosthesis, followed by institution of an extra-anatomical bypass to restore blood flow. On many occasions this procedure can be staged, with several days intervening between operations; however, in the case of hemorrhage this will not be feasible. If the prosthesis is infected but there is no hemorrhage from suture line involvement, one may perform the staged procedure of instituting an extra-anatOInical bypass with a hiatus of several days before the prosthesis is removed. The judicious and continued use of the proper antibiotics during this period of time is mandatory to prevent infection of the new prosthesis by blood-borne bacteria. The various types of extra-anatOInical bypasses have been well outlined by many authors, including ourselves, in past publications. The proper route of extra-anatoInical bypass should be chosen care-
1424
WILLIAM
J.
FRY
fully and the use of autogenous tissue should be emphasized whenever possible. The autogenous saphenous vein for the extra-anatomical bypass, while not immune from infection, certainly is a safer graft to use in that it is viable tissue.
CONCLUSION During the past 5 years, with the institution of prophylactic antibiotics during the course of arterial reconstructive operations there has been a change in the organisms causing prosthetic infections. We believe this is due to the judicious use of oxacillin as a prophylactic antibiotic agent. Gram-negatives organisms have been found in the bag holding the intestines during aortic resection. We have added to the prophylactic antibiotic therapy the drug kanamycin in an effort to suppress the chance for prosthetic contamination with the gram-negative organism.
REFERENCES 1. Barker, W. F.: Peripheral Arterial Disease. Philadelphia, W. B. Saunders Co., 1966. 2. Diethrich, E. B., Noon, G. P., Liddicoat, J. E., and DeBakey, M. E.: Treatment of infected aortofemoral arterial prosthesis. Surgery, 68:1044,1970. 3. Fry, w. J., and Lindenauer, S. M.: Infection complicating the use of plastic arterial implants. Arch. Surg., 94:600, 1967. . 4. Healey, S. J., Wheeler, B., Crane, C., and Warren, R: Reconstructive operations for aortoiliac obliterative disease. New Eng. J. Med., 271:1386,1964. 5. Hoffert, P. W., Gensler, S., and Haimovici, H.: Infection complicating arterial grafts. Arch. Surg., 90:427, 1965. 6. Javid, H., Julian, O. C., Dye, W. S., and Hunter, J. A.: Complications of abdominal aortic grafts. Arch. Surg., 85:650, 1962. 7. Lindenauer, S. M., Fry, W. J., Schaub, G., and Wild, D.: The use of antibiotics in the prevention of vascular graft infections. Surgery, 62:487, 1967. 8. Smith, R F., and Szilagyi, D. E.: Healing complications with plastic arterial implants. Arch. Surg., 82: 14, 1961. 9. Szilagyi, D. E., Smith, R F., Elliott, J. P., and Vrandecic, M. P.: Infection in arterial reconstruction with synthetic grafts. Presented at the Annual Meeting of the American Surgical Association, San Francisco, California, April 26-28, 1972.
Department of Surgery Section of General Surgery University of Michigan Medical Center Ann Arbor, Michigan 48104