Deliberate Renal Ischemia

Transcription

1 Deliberate Renal Ischemia A Valuable and Safe Adjunct During Operations upon the Abdominal Aorta Robert K. Brawley, M.D., R. Darryl Fisher, M.D., Tom R. DeMeester, M.D., and Ronald C. Elkins, M.D. ABSTRACT Eleven patients are reported in whom operative suprarenal aortic occlusion was employed. Periods of bilateral renal ischemia ranged from 10 to 120 minutes. Postoperative renal function was excellent in all patients undergoing ischemic periods of 34 minutes or less. Renal hypothermia, accomplished by perfusing the kidneys with cold Ringer s solution, was used in 1 patient in whom blood flow to both kidneys was interrupted for 50 minutes. Renal function after operation in this patient was also excellent. Anuria resulted in the death of 1 atient following 120 minutes of bilateral normothermic renal ischemia. The a (P vantages of suprarenal aortic occlusion and deliberate renal ischemia during operation upon the abdominal aorta are discussed. T emporary occlusion of the suprarenal aorta may be helpful, or even necessary, during operation in patients with aortic laceration, atherosclerotic aortic occlusion, or aneurysm of the aorta. However, the duration of renal ischemia after which the human kidney will resume function sufficient to prevent oliguria and azotemia is unknown, and therefore surgeons have been reluctant to employ suprarenal aortic occlusion because of the uncertainty of the safe limit of renal ischemia. This report describes our experience with 11 patients who required periods of suprarenal aortic occlusion during operations upon the aorta. Clinical Material The clinical courses of 11 patients who required temporary interruption of renal blood flow during operation upon the aorta are outlined in the Table. Injuries, atherosclerotic occlusions, and aneurysms were the three types of aortic lesions encountered. Three patients having different aortic lesions and illustrating the various applications of this technique are described below in detail. PATIENT 2 A 59-year-old man underwent operation for an abdominal stab wound. At laparotomy, bleeding from the upper abdominal aorta was encountered. From the Department of Surgery, The Johns Hopkins University School of Mediaine, Baltimore, Md. Accepted for publication Oct. 13, Address reprint requests to Dr. Brawley, Department of Surgery, The Johns Hopkins Hapital, Baltimore, Md THE ANNALS OF THORACIC SURGERY

2 SUMMARY OF THE COURSES OF 11 PATIENTS IN WHOM DELIBERATE BILATERAL RENAL ISCHEMIA WAS EMPLOYED DURING AORTIC OPERATION 1: 0 e Patient Age No. (yr.) 1 82 Gunshot wound of thoracic aorta Stab wound of abdominal aorta Gunshot wound of abdominal aorta Atherosclerotic occlusion Atherosclerotic occlusion Atherosclerotic occlusion 71 False aneurysm of Duration of Bilateral Renal Postoperative Ischemia Postoperative Renal Lesion (min.) Course Function abdominal aorta Abdominal aneurysm 30 Uncomplicated Excellent Uncomplicated Excellent Renal failure, t ;d 9 L1 r CD -3 N Y death Uncomplicated Anuria Excellent Uncomplicated Excellent Uncomplicated Excellent Gastrointestinal hemorrhage; recovered Aspiration pneumonia & death on tenth postop. day Myocardial infarction; recovered Uncomplicated Respiratory distress syndrome; recovered Excellent 25 Excellent 69 Abdominal aneurysm 50a Excellent w 'Under hypothermia. M -3 Abdominal aneurysm Abdominal aneurysm Excellent Fair

3 BRAWLEY ET AL. Proximal control of the aorta was obtained at the diaphragmatic aortic hiatus. Further inspection disclosed an aortic laceration at the level of the superior mesenteric artery. The segment of aorta which gave origin to the superior mesenteric artery was isolated with vascular clamps, and vascular repair was accomplished during 22 minutes of suprarenal aortic occlusion. A second 12 minutes of aortic occlusion was required to control a posterior leak. The patient s postoperative recovery was uncomplicated, and he was discharged 19 days following injury. Azotemia and oliguria did not occur following operation. PATIENT 4 A 56-year-old man was admitted with signs of acute ischemia of the lower extremities. Aortography demonstrated complete occlusion of the aorta just distal to the renal arteries (Fig. 1). At operation, the aorta was clamped immediately proximal to the renal arteries after systemic administration of heparin. A 5 cm. aortotomy beginning below the renal arteries provided exposure of the ostia of the renal arteries and allowed aortic endarterectomy. The aorta was flushed of thrombus and other particulate matter by momentarily releasing the aortic clamp. During these periods of aortic flushing, the renal arteries were temporarily occluded to prevent embolism of particulate matter. Following aortic endarterectomy and flushing, the aortic clamp was moved to a position below the renal arteries yet proximal to the aortotomy. A knitted Dacron prosthesis was then inserted between the aortotomy and the iliac arteries. Bilateral renal ischemia lasted 15 minutes. The patient s postoperative recovery was uncomplicated, and at no time was there any indication of impaired renal function. FIG. 1. Aortogram in Patient 4, who had high aorto-iliac occlusion. The aorta is completely obstructed just distal to the origin of both renal arteries. 358 THE ANNALS OF THORACIC SURGERY

4 Renal Ischemia, a Safe Adjunct PATIENT 9 A 69-year-old man was transferred to this hospital after an abdominal exploration had revealed an aortic aneurysm involving the renal arteries. Subsequent aortography demonstrated an aortic aneurysm extending above the renal arteries (Fig. 2). At operation, the aorta was clamped between the superior mesenteric and the renal arteries (Fig. 3A) and the anterior wall of the aneurysm was excised. The left renal artery, which arose from the wall of the aneurysm, was detached from the aneurysm along with a small cuff of aortic wall. It was possible to transect the aorta so that the right renal artery remained attached to the proximal aortic cuff. Through small catheters inserted into the renal arteries, each kidney was perfused with 500 ml. of iced lactated Ringer s solution containing 2,000 units of heparin. Both renal arteries were then temporarily occluded with clamps. A knitted Dacron prosthesis was sewn to the proximal aorta (Fig. 3B). The aortic clamp was then repositioned onto the prosthesis (Fig. 3C) so that perfusion of the right kidney was reestablished. The left renal artery was implanted into the prosthesis, and the aortic clamp was replaced below the left renal artery (Fig. 3D). Blood flow to the left kidney was thereby reestablished. Bilateral iliac anastomoses were then performed. Both kidneys were ischemic for 50 minutes, and the left kidney was ischemic for an additional 10 minutes. This patient s postoperative course was satisfactory. His urine output, serum urea nitrogen, and serum creatinine remained normal throughout his convalescence. FIG. 2. Aortogram in Patient 9, who had an abdominal aortic aneurysm at the level of the renal arteries. At operation the left renal artery was found to arise from the aneurysm wall while the right renal artery took its origin from the aorta immediately above the aneurysm.

5 BKAWLEY ET AL. FIG. 3. The technique used for aneurysmectomy in Patient 9. (A) The aneurysm has been exposed and the aorta occluded just below the origin of the superior mesenteric artery. (B) The aneurysm has been incised and the left renal artery, which arose from the wall of the aneurysm, has been detached along with a small cufl of aortic wall. The aorta has been transected so that the right renal artery remained attached to the proximal aortic cufl, since the aorta in this area was not involved with aneurysm. Both renal arteries have been flushed with 100 ml. of iced Ringer's solution containing 2,000 units of heparin and have been occluded with clamps. The proximal anastomosis between the aorta and the prosthesis is being completed. (C) The vascular clamp has been repositioned onto the prosthesis and perfusion of the right kidney reestablished. Implantatron of the left renal artery into the prosthesis is being completed. (D) The clamp has been moved below the level of the left renal artery implantation, and aortic perfusion of both renal arteries has resumed. The iliac anastomoses are being completed. Operative Technique Operative exposure of the upper abdominal aorta and its branches is accomplished through a long midline or a thoracoabdominal incision. The method for isolating the aorta in the upper abdomen has been described [5, 61 and consists of exposure through a left retroperitoneal appraach with reflection of the viscera and retroperitoneal structures to the right. The necessity for suprarenal aortic clamping is obvious in patients with aortic injuries located at or above the renal arteries (as in Patient 2). Blood in the lesser peritoneal sac, especially in the absence of free blood in the greater peritoneal space, is often an indication that suprarenal aortic injury has 360 THE ANNALS OF THORACIC SURGERY

6 Renal Ischemia, a Safe Adjunct occurred. When hemorrhage is severe in these patients, control of the bleeding should be obtained by clamping the aorta at the diaphragmatic hiatus. Occasionally it may be necessary to obtain control of the thoracic aorta through a left anterior thoracotomy. Exposure of the upper abdominal aorta can then be obtained by reflecting the spleen, tail of the pancreas, and splenic flexure of the colon to the right [6]. The vascular clamp often can be repositioned below the visceral aortic branches after the extent of the injury has been demonstrated. Once the precise location and nature of the injury have been determined, the injured aorta can be isolated between clamps and repaired. If the aorta must be clamped above the renal arteries, our experience indicates that the period of ischemia should be limited to 30 minutes unless renal hypothermia is employed. The technical advantage provided by suprarenal aortic clamping is also important during operations in patients with aortic occlusion extending to the renal arteries (see Fig. 1). Fresh thrombus often accounts for much of the aortic obstruction in these patients, but areas of atherosclerosis may extend proximally from the aortic bifurcation to the renal arteries. Aorta-to-iliac bypass can best be performed in these patients following endarterectomy of a segment of the infrarenal aorta. This procedure can be easily accomplished through a vertical aortotomy made immediately below the level of the renal arteries during temporary aortic occlusion above the renal arteries (as in Patient 4). The period of renal ischemia necessary to perform the endarterectomy and to flush the aortic segment usually is less than 30 minutes. Following these maneuvers, the aortic clamp can be repositioned distal to the renal arteries yet proximal to the aortotomy. The proximal anastomosis between the prosthesis and the aortotomy can be performed during renal artery perfusion from the aorta. Suprarenal aortic occlusion is always necessary in patients with aneurysm involving the renal arteries (see Fig. 2). In some instances it is possible to render only one kidney ischemic while performing the necessary dissection and anastomosis. Diagonal placement of the vascular clamp between the two renal arteries will prevent or diminish ischemia of one kidney by allowing perfusion of that kidney from the aorta. In patients whose aneurysm extends to, but not above, the renal arteries, it is often advantageous to have an additional length of the proximal aortic cuff for easier placement of the proximal sutures. If the aortic clamp is placed below the renal arteries in these patients, it is necessary to attach the prosthesis to an aortic cuff which is actually the upper portion of the aneurysm. By moving the aortic clamp above one or both renal arteries, additional aneurysm can be resected and the prosthesis can be sutured to less friable and stronger aortic wall. Renal ischemia necessary to allow the placement of an anastomosis between graft and proximal aorta is usually less than 30 minutes, a period of renal ischemia which should be safe for most patients. When the renal arteries or other visceral aortic branches arise from the aneurysm, periods of renal ischemia greater than 30 minutes may be neces-

7 BRAWLEY ET AL. sary for excision of the aneurysm, insertion of the prosthesis, and implantation of aortic branch arteries (as in Patient 9). In these situations, induced renal hypothermia can provide renal protection during the longer periods of ischemia. With the aorta clamped proximal to the renal arteries, the aneurysm can be incised (see Fig. 3). The renal arteries are then detached from the aneurysm while retaining a cuff of aorta about the ostium of each renal artery. The renal arteries are flushed with 500 ml. of iced Ringer s lactate solution containing 2,000 units of heparin. Each renal artery is occluded, and the anastomosis between the proximal aorta and the prosthesis is performed. One renal artery is then reimplanted into the prosthesis. The clamp is moved onto the prosthesis below the site of renal artery implantation, thereby reestablishing blood flow to that kidney. The second renal artery is reimplanted into the prosthesis, and again the vascular clamp is moved below the level of the second renal artery implantation, thus restoring blood flow to both kidneys. The distal anastomoses are then performed. Comment Laboratory studies indicate that animals tolerate relatively long periods of renal ischemia. Rats will survive two hours of thoracic aortic occlusion [lo], and dogs tolerate two hours of aortic occlusion with only a temporary and slight reduction in renal function [9]. Rabbits, however, died with renal failure following one hour of renal ischemia [l], and most animals exhibit fatal renal failure if the kidneys are deprived of blood flow longer than two hours. Surgeons have been reluctant to render the kidneys of patients ischemic during operations upon the aorta because the safe duration of renal ischemia in man has not been clearly established. Consequently, the effects of temporary interruption of blood flow to both kidneys have rarely been evaluated clinically. DeBakey, Creech, and Morris [5] reported 4 patients who required resection of thoracoabdominal aneurysms. Hypothermia (322 C.) was utilized in 1 patient who required 105 minutes of bilateral renal ischemia. This patient died with renal failure one week postoperatively. Three other patients survived aneurysmectomy during which shunts were used temporarily to bypass the occluded aorta and thus diminish the period of renal ischemia. Bilateral renal ischemia in these 3 patients ranged from 0 to 23 minutes. Bahnson [Z, 31 has reported patient survival following 37 minutes of bilateral renal ischemia and death from renal failure in another patient in whom both kidneys were ischemic for 110 minutes. Others have advocated suprarenal aortic clamping during endarterectomy for high aorto-iliac occlusion and renal revascularization [4, 7, 81. The reported periods of bilateral renal ischemia required to accomplish these maneuvers have varied from 4 to 24 minutes [8]. Our experience with 11 patients indicates that renal ischemia of 30 min- 362 THE ANNALS OF THORACIC SURGERY

8 Renal Ischemia, a Safe Adjunct Utes duration is safe and does not significantly depress renal function. One of our patients (Patient 3) required two hours of normothermic renal ischemia to repair an extensive gunshot wound of the visceral branches of the aorta. He died in renal failure. Another patient (Patient 11) had a transient rise in serum creatinine and a temporary reduction in creatinine clearance following 40 minutes of normothermic renal ischemia. On the other hand, in Patient 9, 50 minutes of bilateral renal ischemia after the kidneys were flushed with cold Ringer s lactate resulted in no detectable change in renal function. Clinical experience with renal homotransplantation has demonstrated that the human kidney usually resumes satisfactory function after eight to ten hours of complete ischemia if the transplanted kidney has been cooled and flushed soon after removal from the donor patient. Experimental evidence indicates that the safe period of renal ischemia may vary depending upon the constitution of the renal perfusate [ll]. It is our opinion, based upon the 11 patients presented here and previously reported clinical experience, that bilateral normothermic renal ischemia for periods of 30 minutes is safe for patients in whom renal function is normal or nearly normal preoperatively. It is currently our practice to perfuse the kidneys with iced Ringer s lactate solution containing heparin if the ischemic period is likely to be greater than 30 minutes. References Badenoch, A. W., and Darmady, E. M. Effects of temporary occlusion of the renal artery in rabbits and its relationship to traumatic uraemia. J. Pathol. Bacteriol. 4:79, Bahnson, H. T. Definitive treatment of saccular aneurysms of the aorta with excision of sac and aortic suture. Surg. Gynecol. Obstet. 96:383, Bahnson, H. T. Treatment of abdominal aortic aneurysm by excision and replacement by homograft. Circulation 9:414, Chaves, S. M., Conn, J. H., Fain, W. R., and Gee, H. L. Surgical treatment of high aorto-iliac occlusion. Surgery 65:757, DeBakey, M. E., Creech, O., Jr., and Morris, G. C., Jr. Aneurysm of thoracoabdominal aorta involving the celiac, superior mesenteric and renal arteries: Report of four cases treated by resection and homograft replacement. Ann. Surg. 144:549, Elkins, R. C., DeMeester, T. R., and Brawley, R. K. Surgical exposure of the upper abdominal aorta and its branches. Surgery 70:622, Ernst, C. B., and Fry, W. J. Temporary aorta-left renal vein transposition: A simplified approach to the management of the aortic cuff in high aortic occlusions. Surgery 69:314, Gomes, M. M. R., and Bernatz, P. E. Aorto-iliac occlusive disease: Extension cephalad to origin of renal arteries with surgical considerations and results. Arch. Surg. 101:161, Hamilton, P. B., Phillips, R. A., and Hiller, A. Duration of renal ischemia required to produce uraemia. Am. J. Physiol. 152:517, Koletsky, S. Effects of temporary interruption of renal circulation in rats. Arch. Pathol. 58:592, Woods, J. E., Holley, K. E., and Pheteplace, B. A. Kidney preservation by initial perfusion and surface cooling. J. Surg. Res. 11:68, VOL. 13, NO. 4, APRIL,