Renal Failure after Operation for Abdominal Aortic Aneurysm Peter Skov Olsen, Torben Schroeder, Mario Perko, Ole C. Rgder, Kim Agerskov, Steffen Sgrensen, Jgrgen E. Lorentzen, Copenhagen, Denmurk

Among 656 patients undergoing surgery for abdominal aortic aneurysm, 81 patients (12%) developed postoperative renal failure. Before operation hypotension and shock occurred in 88% of the patients with ruptured aneurysm, whereas none of the patients operated electively were hypotensive. Dialysis was performed in 32 patients, while the remaining 49 patients were managed without dialysis. Within 30 days after the operation 47 patients (58%) had died. There was no difference in mortality between patients in dialysis and patients managed without dialysis. Thirteen patients died during follow-up. In six cases the death was caused by renal failure only or in combination with failure of other organs. Analysis of the cumulative survival shows that, if the patients survive the postoperative period, their life expectancy is comparable to that of patients without renal complications. (Ann Vasc Surg 1990;4: 58&583). KEY WORDS: Renal failure, postoperative; abdominal aortic aneurysm; renal dialysis, postoperative.

The operative treatment of abdominal aortic an- postoperative renal failure after operation for AAA eurysm (AAA) with resection and prosthetic re- performed during the decade 1979-88. placement has shown a steady increase during the last decades with a concomitant decrease in mortality [1,2]. The decrease in mortality has led to a MATERIAI AND METHODS reappraisal of the indications for surgery of aortic aneurysms. Aneurysmectomy is now recommended From 1979 through 988, 656 patients were opereven in higher risk patients, including patients with ated on for AAA. k i r average age was 69 years coronary artery disease, patients over 80 years of age and patients with impaired renal function [3-51. (range 39-100). All operations consisted of resection of the aneuCardiac complications, pulmonary complications, and renal failure are still frequent, especially in rysm and implantation of a prosthesis by the inlay patients with ruptured aneurysm [6,7]. The mortal- technique. The record of each patient was reviewed ity for patients with postoperative renal failure has with regard to age, sex, associated diseases, prepreviously been reported as high as 50-9492 [8,9]. operative clinical status, operative management, This study presents a survey of the patients with postoperative complications, mortality and survival. Postoperative renal failure was defined as a raise in serum creatinine above 200 pmolil from a From the Department of Vusciilar Siirgery, R K , Rigshos- level below 130 pmol/l. In patients with previously impaired renal function, renal failure was defined as pitalet, Copenhagen, Denmark. a doubling of the serum creatinine concentration. Reprint requests: Peter S k o v Olsen, Depmrtment of Siirgesy, R , KAS Gentofte, Niels Andrrsens Vej 65, 2900, Dialysis was initiated in patients with a rapidly increasing serum creatinine, who were oliguric/ Hellerup, D e n m u r h . 580

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RENAL FAILURE AF7ER AAA

RENAL FAILURE

0NO RENAL COMPLICATIONS

-

n=151 I

n.218

/

/

138(9 l0/c)

162(74%)

TABLE 11.-Preoperative concentration of creatinine in serum from patients operated upon for abdominal aortic aneurysm

Postoperative renal Preoperative failure creatinine No renal w/o wl mmolll complications dialysis dialysis 5 0.13 (n = 492) 446 25 (5%) 21 (4%) > 0.13 - . . - -.and .5 0.27 (n = 140) 113 19 (14%) 8 (6'/0) > 0.27 and 5 0.53 (n = 24) 16 5 (21yo) 3 (1 3%) > 0.53 (n = 0) 0 0 0 Of 164 patients with a preoperative creatinine > 0.13, 35 (21%) developed postoperative renal failure, compared to 46 patients (9%) of 492 with a normal creatinine (p = 0.002, Fisher's test).

(2 1%) than patients without preoperative renal problems (9%) (Tables I, 11). r7-5J-z Hypotension or shock was not observed in patients developing renal failure after elective operaELECTIVE RUPTURED tion. whereas 88% of the patients with ruptured aneurysm were in shock before the operation. PostFig. 1. Renal failure in elective, acute, and ruptured operative renal failure occurred in 29% of the pacases compared to patients without renal complica- tients with a preoperative median systolic blood tions. pressure less than 100 mmHg. Similarly, 33% of the patients with hypotension for more than five minutes and 28% of the patients with preoperative anuria deanuric, or who demonstrated overhydration or hy- veloped postoperative renal failure (Table 111). The frequency of renal failure increased with increasing perkalemia. amounts of prcoperative bleeding (Table IV). Within 30 days after the operation 47 patients with renal failure had died, a mortality of 58%. RESULTS Patients treated by dialysis had a mortality similar Postoperative renal failure occurred in 8 I patients to patients managed without dialysis. We found no (12%) (71 men and 10 women). The average age was difference in mortality between those with elective, 72 years (range 49-86). Fifty-six (69%) of the pa- acute and ruptured aneurysms (Table V). There was tients with postoperative renal failure were oper- no difference in postoperative mortality between ated on for a ruptured aneurysm (Fig. 1). Dialysis patients with a normal preoperative serum creatiwas performed in 32 patients, while 49 patients nine and in patients with an elevated preoperative were managed without dialysis. Patients with a serum creatinine. preoperative impaired renal function revealed a Thirty-four patients (42%) survived for more than higher incidence of postoperative renal failure 30 days. At the time of follow-up 21 patients were

TABLE I.-Associated

diseases in 81 patients with renal failure after operation for abdominal aortic aneurysm

Preoperative risk factor Impaired renal function Arteriosclerotic heart disease Hypertension Diabetes Chronic obstructive pulmonary disease Cerebrovascular disease Peripheral arterial vascular disease ap < 0.002 compared with patients with renal failure. bnot significantly different from patients with renal failure.

Postoperative renal failure w/o dialysis w/ dialysis In = 49) In = 32) 24 (49%) 11 (34%) 9 (18%) 11 (34%) 5 (10%) 9 (28%) 2 (4%) 2 (6%) 0 1 (3%) 2 (4%) 2 (6%) 9 (1 8%) 6 (19%)

No renal complications In = 5751 129" (22%) 148b (26%) 132b (23%) 12b (2%) 53; (9%) 25 (4%) 12Ob(21%)

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A N N A L S 01

R E N A L FAILURE AFTER AAA

TABLE Ill.-Clinical condition at operation of AAA

TABLE V.-Mortality

in patients with postoperative renal failure compared to patients without renal complication after AAA

patients developing postoperative renal failure

Condition Median preoperative systolic blood pressure < 100 mmHg (n = 137)

Hypotension > 5 rnin (n = 71)

Anuria (n

=

99)

Postoperative renal failure wlo wl Rupture dialysis dialysis 123 (90%) 24 (18%) 15 (1 1O h )

Mortality in patients with renal failure n = 81 ( O h ) 7 (58%) 7 (54%) 33 (59%)

Elective Acute Ruptured

61 (86Yo) 14 (20%) 9 (13%)

VASCULAR SURGFKY

ap

-

Mortality in patients without renal complications n = 575 (%) 7” (2.5%) 19” (13.8%) 50” (30.8%)

0 002 compared to mortality in patients with renal failure

81 (82%) 19 (19%) 9 (9%)

still alive and had a normal renal function. Among the remaining 13 patients, who died during followup, the deaths of six were caused by renal failure alone or in combination with failure of other organs. Analysis of the cumulated survival showed that after five years two-thirds of the patients with renal failure had died (Fig. 2). There was no difference in survival among those with elective, acute and ruptured aneurysms. DISCUSSION Despite a decrease in morbidity and mortality after operation for AAA during the last decade, postoperative renal failure continues to be a frequent complication [ 10,l I]. Previous studies have reported an incidence of renal failure of 5-1095 in elective cases and up to 57% in patients with ruptured aneurysm [6,10,11]. Improvement in perioperative fluid management to prevent hypotension has reduced the incidence of postoperative renal failure [5,10]. We observed renal failure in 4% of the patients operated upon electively and in 26% of the patients with ruptured aneurysm. These frequencies of renal failure occurred despite intensive preand postoperative care, especially with regard to

volume expansion and control of cardiac performance with pulmonary artery catheterization in selected cases. Although a significantly larger number of the patients with preoperative impaired renal function developed postoperative renal failure compared to the group of patients with a normal preoperative serum creatinine, no difference in the requirement for hemodialysis was found between the two groups. This suggests that patients with mildly impaired renal function will undergo aortic aneurysm repair with double the risk of postoperative renal complications. This is in contrast to the early results with aortic aneurysmectomy, which were often complicated by renal failure, uremia and a high mortality [12]. None of the patients operated on electively who developed postoperative renal failure had any history of hypotension and shock, whereas 88% of the patients with ruptured aneurysm were in shock at the time of admission. Experimental studies have shown that infrarenal aortic cross-clamping can induce renal vasoconstriction and thus renal hypoperfusion leading to postoperative renal failure [12,13]. This form of renal failure can be prevented by adequate volume expansion. Therefore renal

%

1001 \---100

-_ --\

bleeding in patients developing renal failure after AAA*

ml

< 2500

(n = 346) 2500-5000 (n = 218) > 5000 (n = 92)

Renal failure without dialysis n (%) 13 (4%)

Renal failure with dialysis n (‘Yo) 6 (2%)

20 (9YO)

15 (7%)

16 (17%)

11 (12%)

~I

‘The frequency of renal failure was significantly higher in patients with perioperative bleeding of 2500-5000 ml compared to the group < 2500 mi (p c 0.001) and also significantly higher in the group > 5000 mi compared to the group 2500-5000 ml (p < 0.01) (Fisher’s exact test).

\\ \

BACKGROUND

80

TABLE IV.-Median amount of perioperative

. . .-

\

60

\

401

I

1

2

3

YEARS4

5

6

Fig. 2. Cumulative survival for patients with renal failure and for patients without renal complications compared to an age and sex matched background population (life-table method).

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R E N A L FAILURE AFTER A A A

failures due to ischemic injury to the kidney during elective operation for AAA have become fairly infrequent 114,151. Renal failure in elective patients in this study is probably a result of renal infarction and thrombosis or renal microembolization [ 161. The higher frequency of renal failure in patients with ruptured aneurysm and in shock by the time of admission is most likely related to renal ischemia due to hypovolemia before operation. Studies in dogs have shown that kidneys exposed to ischemia before laparotomy are much more sensitive to variations in blood pressure under the operation from bleeding. clamping and declamping of the aorta and thereby to development of postoperative renal failure [ 171. Despite a fall in the overall mortality after operation for AAA, mortality from postoperative renal failure continues to be high. Following operation for ruptured aneurysm, renal failure was previously reported to be associated with a mortality of 8894% [8,18] and more recently a mortality of 50-54% was reported [6,11]. Johnston and associates [lo] found a mortality of 31% in patients with renal failure requiring hemodialysis after operation for nonruptured aneurysm. We found an overall mortality of 58% for patients with postoperative renal failure. No difference with respect to indications for surgery was found (Table V). Patients treated without dialysis and patients requiring hemodialysis had a similarly high mortality. This suggests that the mortality for patients with renal failure managed without dialysis might not be improved by early hemodialysis. Previous reports have greatly advocated the use of early and aggressive hemodialysis to reduce the postoperative mortality from acute renal failure [19]. However, this early optimistic view has not been confirmed in more recent studies, where a mortality of 79% and 69% was reported for patients in dialysis [20,21]. Further efforts should therefore be directed towards prevention of renal failure after operation for AAA. Such measures include control of optimal cardiac performance, hemodynamic monitoring, total parenteral nutrition and volume expansion. Agents for organ protection and prevention of reperfusion injury are under investigation and appear to be useful [22]. However, the moment the patient develops an acute renal failure, his prognosis is much dimmer with a high chance of postoperative mortality. If the patient survives the postoperative period, his long-term survival parallels the survival of patients without renal complications.

583

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