Risk of CAPD in Obese Patients

Obesity is often considered a relative contraindi- cation to continuous ambulatory peritoneal dialysis because of anticipated problems with the catheter as well as the caloric load of the glucose in the dialysis fluid. Are there, in fact, data available on these points which quantitate the risks (if any)?

A number of papers have suggested that obese patients have an increased incidence of continuous ambulatory peritoneal dialysis (CAPD) treatment failure due to access-related problems, further weight gain, and metabolic abnormalities resulting from the caloric load of dialysate glucose (1). A recent report describes similar rates of peritonitis, catheter infec- tion, and catheter loss due to dialysate leaks and outflow obstruction (2) for obese and nonobese pa- tients. For unclear reasons, obese patients in this study had an increased risk of catheter loss due to Staphylococcus aureus infections, although not more of these infections. Our experience (3) with 24 obese patients entering CAPD with body weights >120% of their ideal body weight has been positive and is presented below.

All patients underwent successful peritoneoscopic placement of the dialysis catheter without technical difficulties. None experienced postoperative prob- lems such as dialysate leakage or migration (albeit a “husky” catheter suited to fit a thicker abdominal wall was used). One patient required partial omen- tectomy 16 months after initiating CAPD to correct

outflow obstruction caused by omental wrapping. After one year on CAPD, these patients, when com- pared to normal-weight counterparts, were less likely to gain weight (average loss of 0.7 kg for obese patients versus an average gain of 4.1 kg for normal weight controls; p = 0.001). Similarly, obese patients had a lower incidence of peritonitis and exit site infection than normal-weight controls.

From this experience we conclude that obese pa- tients can successfully undergo CAPD without fear of further weight gain. Access creation for the obese abdomen is facilitated by the availability of newer devices and methods of implantation (4). Obese pa- tients with end-stage renal disease should not be dissuaded from choosing CAPD because of their excessive weight.

Cosme Cruz, Detroit, MI

References 1. Schleifer CR, Ziemek H, Raimondo J, et al.: CAPD failure in the obese

diabetic; The “jellybelly” syndrome. Peritoneal Dial Int 8(Suppl): 149, 1988

2. Piraino B, Bernardini J, Centa PK, Johnston JR, Sorkin M, et al.: The effect of body weight on CAPD-related infections and catheter loss. Peritoneal Dial Int 8:64-68, 1991

3. Pikus R. Cruz C: CAPD and obesitv (Abstract). Peritoneal Dial Int ~. 1 I(Suppl):207, 1991

4. Cruz C, Faber M D Peritoneoscopic implantation of catheters for peritoneal dialysis: Effect on functional survival and incidence of tunnel infection. Conirib Nephrol89:35-39. 1991

Pre-Transplant Transfusion Policy

In the past, frozen, washed red cells were used to transfuse dialysis patients in order to minimize sen- sitization and increase the chance of the patient’s obtaining a successful renal transplant. When it was shown that conventional transfusions actually in- creased the success rate for transplants, that practice was abandoned. Since the development of cyclo- sporin, many centers feel that the additional immu- nologic benefit derived from planned, conventional transfusions does not justifv their risks. It is unclear to me, however, what to transfuse into the dialysis

patient who needs blood. Should I use leukocyte- depleted (by filter) blood (this having replaced frozen, washed cells) to minimize sensitization or conven- tional blood to provide whatever additional benefit it offers for a future transplant?

The issue of pretransplantation blood transfusion remains controversial because data from Gerhard Opelz’s Collaborative Transplant Study and the UCLA registry conflict.

Opelz’s data showed that over the years 1982 to

Dialysis Clinic welcomes questions of general interest to the journal’s readership. Questions should be typed, double- spaced and sent to Seminars in Dialysis, Department of Medicine (Nephrology), 1 Robert Wood Johnson Place, CN-19, New Brunswick, NJ 08903. Unpublished questions cannot be answered or returned. Authors of questions will

The purpose of Dialysis Clinic is to educate and inform, not to give medical advice regarding a specific patient. Med- icine is complex and patient-specific advice requires more details, both in the question and the answer, than can be provided. Information offered here should be checked with appropriate sources before it is used in diagnosis and ther-

be identified unless otherwise requested. apy. 284

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1986, overall 1 -year graft survival improved for transfused and nontransfused, cyclosporine-treated and conventionally treated patients. Opelz’s data showed that for 3 consecutive years, success rates for nontransfused patients were nearly as good (no sta- tistically significant differences) as those for trans- fused patients in both cadaver and 1 haplotype matched living related transplants. Donor specific transfusion conferred no additional benefit.

The UCLA registry data also showed a diminished “transfusion effect” from 12%* in 1980 to 3%* in 1988-1989. The optimal number of required trans- fusions has also declined from 5-10 to 2-3, and the percentage of patients transplanted without transfu- sion has increased from 10% (1984) to 34% (1989). However, the UCLA registry data continue to show a significant transfusion effect at 1 year that is great- est for black and Asian recipients (6%-7%),* HLA- DR mismatched recipients (4%),* pediatric donor kidneys ( lo%),* and second cadaver transplant sur- vival (lo%).*+

Of greater concern are the possible long-term ef- fects of blood transfusions. Nontransfused patients may have greater risk and seventy of early rejection episodes in the first year,* and a higher subsequent graft loss rate after the first year.

There is clearly an effect of blood transfusion on immunity and the effect is long lasting. However, a 3%-5% improvement in 1-year graft survival may not confer sufficient benefit for the added risk of human immunodeficiency virus infection, hepatitis C infection, and development of lymphocytotoxic

* Difference from nontransfused. t Transfusion had to occur prior to the first transplant to confer benefit on the second transplant. $ Nontransfused versus transfused: risk of early rejection: 42% versus 26%: 1-year survival rate among those with rejection: 56% versus 67%; I-year survival rate among those without rejection: 83% versus 89%.

antibodies. Some centers have abandoned a trans- fusion policy. The final answer will emerge when the number of nontransfused recipients increases and more accurate analysis of long-term benefits is avail- able.

The use of red blood cell and platelet leukocyte filters results in a 2 to 3 log reduction in the number of leukocytes transferred with each transfusion (i.e., from 1 to 3 x lo9 leukocytes to 5107 leukocytes). This degree of leukocyte depletion appears to be sufficient to prevent transmission of cytomegalovi- rus, but is sufficient only to delay but not to prevent lymphocytotoxic antibody formation. (Filters have not been approved for prevention of graft versus host disease.)

The blood transfusion policy at Oregon Health Sciences University is the following:

1. Clinically necessary transfusions (for anemia) are given with American Red Cross approved leukocyte filters.

2. One “protocol” transfusions is given to all trans- plant recipients (identical, haplo-identical, and zero-matched living related and unrelated and cadaveric recipients).

3. Donor-specific transfusions are not given.

Mary Meyer, Portland, OR

References I . Cecka JM, Toyatome A: The transfusion effect, in Clinical Trunsplanrs.

edited by Terasaki P. The Regents of the University of California, 5:335-341, 1989

2. Opelz G. To transfuse or not before transplantation. Edited by Moms PJ, Tilney N. Philadelphia, W. B. Saunders Co., 2:77-85, 1988

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9: One protocol transfusion is equivalent to one unit packed red blood cells (or more ifgiven at any time in the past) or 5 leukocyte- poor units (leukocyte filtered).

Frequency of Vascular Access Stenoses

A number of screening studies using venous pres- sures or recirculation values have shown a high fie- quency of vascular access stenoses. However, I have never seen a study that reports thefvequency of such stenoses in an unscreened hemodialysis patient pop- ulation. Do such data exist?

Yes, they do. Vascular access stenoses are ex- tremely common.

In 1989, all 46 chronic hemodialysis patients at the Medical College of Pennsylvania underwent ven- ography of their dialysis accesses (1). Our dialysis population had 10 arteriovenous native fistulas, 32 polytetrafluoroethylene arm grafts and 4 polytetra- fluoroethylene thigh grafts. There were 56 discrete lesions found with multiple lesions in 26% of pa- tients. Thirty eight of 46 patients had access stenoses

greater than 40%. These stenoses were subdivided into five types with the following incidences: proxi- mal vein, 36%; venous anastomosis, 25%; subclavian vein, 23%; arterial anastomosis, 11%; and intimal hyperplasia in graft, 5 %.

The high frequency of stenotic lesions we found is in agreement with previous retrospective studies showing that outflow stenoses are the most common cause for access failure (2-4). Venous injury due to previous cannulations or other trauma (e.g., surgical) coupled with turbulent blood flow may predispose to intimal and medial hyperplasia (5). Stenosis oc- curred in 82.6% of our patients, but the incidence of graft clotting during our study period of 1 year was only 37%. Thus, in our experience, not all stenoses lead to immediate access failure. Therefore, nonin- vasive predictors of impending access failure are