Volume 13 Number 4 April 1991
Letters to the Editors
565
T a b l e I. Primary patency o f axiHofernoral bypass In~
0-6 6-12 12-24 22-36
At risk
104 61 44 22
Occluded
5 0 4 1
Wi~drawn
In~rv~pa~n~
Cumu~tivepa~n~
Standard error
38 17 18 11
0.941 1.000 0.886 0.939
0.941 0.941 0.834 0.783
0.0256 0,0256 0,0554 0,0716
We are happy to provide information regarding the reason for withdrawal of the 47 patients in the first year of the study. Four patients, as indicated, were withdrawn because their grafts failed. Of the remaining 43 patients withdrawn within the first year interval three patients were withdrawn because of death, two patients were lost to follow-up, and the remaining 38 patients were alive with patent grafts in a follow-up of less than 1 year. The features of the life-table method noted by Dr. Bell, namely a large number of patients in the early follow-up intervals and correspondingly smaller numbers later, are common to nearly all clinical reports in the Jouw'~Kc OF VASCULARSURGERY. The only way to decrease this so-called "front-loading" of the life table is to report the results of studies in which entry into the study was stopped at some arbitrary date considerably prior to the reporting time. Although this is possible, it does not allow up-to-dal:e reports of ongoing clinical series, including all patients operated on to the present. Similarly, the decision as to the length of the life-table follow-up is an arbitrary one and has been chosen by our group to conform with the suggested reporting standards for lower extremity ischemia adopted by the Joint Committee of the vascular societies. We chose to stop the length of the follow-up at 4 years, because up to this point the standard error' of the cumulative patency remained below 10%. It is important for all physicians examining such published reports to be aware of the limitations of the life-table method. However, it is not our intention to claim that the life-table is predictive, which it is not; but only to use it as a convenient method of description of the outcome of operations performed on patients at different times who have been followed for varying intervals. Indeed, many physicians have suggested that life-table results beyond the period of mean follow-up are probably not valid and should be ignored. An important feature of the life-table method is that it allows continuing analysis of an ongoing series. Thus we have continued to enter patients undergoing axillarybifemoral bypass since 1988 when the results of the published paper were compiled. We are happy to present to the readers of the JOURNALOF VASCULARSURGERYas well as to Dr. Bell, the results of this ongoing analysis, which I hope will answer his questions about the reproducibility and durability of these results (Table I).
We are happy that Dr. Bell took interest in our study, and are pleased to be able to provide these additional data to assist in its analysis. Lloyd M. Taylor, M D
Associate Professor of Surgery Division of Vascular Surgery Oregon Health Sciences University 3181 S.W. Sam Jackson Park Rd. OPll Portland, OR 97201-3098
Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations To the Editors:
We found the recent article in the Jou~,qm or VASCULAr, SURGERY, "Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations," by Pomposelli et al. (J Vmc SURG 1990;11:745-52) particularly interesting and similar to our experience with a lesser number of dorsal pedal bypasses. Although foot salvage is eminently possible after a successful dorsal bypass, we have found the distal parallel incisions to be a potential source of significant complications, which on occasion may result in the loss of a patent graft. Many of the technical modifications mentioned by Dr. Pomposelli in his discussion of this fine paper are valuable in reducing the incidence of skin bridge necrosis; however, the longitudinal orientation of the incision overlying the dorsal pedal artery with its perpendicular orientation to the lines of stress can also result in poor wound healing, wound dehiscence, and on rare occasions graft dessication, disruption, and hemorrhage. For this reason, with accurate preoperative localization of the distal outflow site, we now use a transverse incision to expose the dorsal pedal artery. A 3 cm length of dorsal pedal artery can easily be exposed through this incision. Such an incision parallel to the lines of stress reduces wound tension, promotes rapid healing without contractions, and eliminates the skin bridge inherent in the longitudinal incision. We believe that this technical modification efiminates a potential source of complications and should be used when performing dorsal pedal by-passes. Fred A. Weaver, M D Albert E. Yellin, M_D
Department of Surgery University of Southern Cafifornia 1200 N. State St. Los Angeles, CA 90033
Letters to the Editors
565
T a b l e I. Primary patency o f axiHofernoral bypass In~
0-6 6-12 12-24 22-36
At risk
104 61 44 22
Occluded
5 0 4 1
Wi~drawn
In~rv~pa~n~
Cumu~tivepa~n~
Standard error
38 17 18 11
0.941 1.000 0.886 0.939
0.941 0.941 0.834 0.783
0.0256 0,0256 0,0554 0,0716
We are happy to provide information regarding the reason for withdrawal of the 47 patients in the first year of the study. Four patients, as indicated, were withdrawn because their grafts failed. Of the remaining 43 patients withdrawn within the first year interval three patients were withdrawn because of death, two patients were lost to follow-up, and the remaining 38 patients were alive with patent grafts in a follow-up of less than 1 year. The features of the life-table method noted by Dr. Bell, namely a large number of patients in the early follow-up intervals and correspondingly smaller numbers later, are common to nearly all clinical reports in the Jouw'~Kc OF VASCULARSURGERY. The only way to decrease this so-called "front-loading" of the life table is to report the results of studies in which entry into the study was stopped at some arbitrary date considerably prior to the reporting time. Although this is possible, it does not allow up-to-dal:e reports of ongoing clinical series, including all patients operated on to the present. Similarly, the decision as to the length of the life-table follow-up is an arbitrary one and has been chosen by our group to conform with the suggested reporting standards for lower extremity ischemia adopted by the Joint Committee of the vascular societies. We chose to stop the length of the follow-up at 4 years, because up to this point the standard error' of the cumulative patency remained below 10%. It is important for all physicians examining such published reports to be aware of the limitations of the life-table method. However, it is not our intention to claim that the life-table is predictive, which it is not; but only to use it as a convenient method of description of the outcome of operations performed on patients at different times who have been followed for varying intervals. Indeed, many physicians have suggested that life-table results beyond the period of mean follow-up are probably not valid and should be ignored. An important feature of the life-table method is that it allows continuing analysis of an ongoing series. Thus we have continued to enter patients undergoing axillarybifemoral bypass since 1988 when the results of the published paper were compiled. We are happy to present to the readers of the JOURNALOF VASCULARSURGERYas well as to Dr. Bell, the results of this ongoing analysis, which I hope will answer his questions about the reproducibility and durability of these results (Table I).
We are happy that Dr. Bell took interest in our study, and are pleased to be able to provide these additional data to assist in its analysis. Lloyd M. Taylor, M D
Associate Professor of Surgery Division of Vascular Surgery Oregon Health Sciences University 3181 S.W. Sam Jackson Park Rd. OPll Portland, OR 97201-3098
Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations To the Editors:
We found the recent article in the Jou~,qm or VASCULAr, SURGERY, "Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations," by Pomposelli et al. (J Vmc SURG 1990;11:745-52) particularly interesting and similar to our experience with a lesser number of dorsal pedal bypasses. Although foot salvage is eminently possible after a successful dorsal bypass, we have found the distal parallel incisions to be a potential source of significant complications, which on occasion may result in the loss of a patent graft. Many of the technical modifications mentioned by Dr. Pomposelli in his discussion of this fine paper are valuable in reducing the incidence of skin bridge necrosis; however, the longitudinal orientation of the incision overlying the dorsal pedal artery with its perpendicular orientation to the lines of stress can also result in poor wound healing, wound dehiscence, and on rare occasions graft dessication, disruption, and hemorrhage. For this reason, with accurate preoperative localization of the distal outflow site, we now use a transverse incision to expose the dorsal pedal artery. A 3 cm length of dorsal pedal artery can easily be exposed through this incision. Such an incision parallel to the lines of stress reduces wound tension, promotes rapid healing without contractions, and eliminates the skin bridge inherent in the longitudinal incision. We believe that this technical modification efiminates a potential source of complications and should be used when performing dorsal pedal by-passes. Fred A. Weaver, M D Albert E. Yellin, M_D
Department of Surgery University of Southern Cafifornia 1200 N. State St. Los Angeles, CA 90033
