Quimica

Chronic Renal Insufficiency

Chronic renal insufficiency is a serious complication of longstanding SCI, and it causes substantial morbidity and mortality in this setting. In a large necropsy series reported by Tribe and Silver in 1969, renal insufficiency was the primary cause of death in the great majority (75 percent) of cases studied (156). In a subsequent report published in 1977 by Hackler(157) (involving a cohort of World War II and Korean War veterans with traumatic SCI), chronic renal failure was found to be the principal cause of death in 45 percent of patients. An additional report by Borges and Hackler (involving a group of Vietnam War veterans with SCI) demonstrated a further reduction in the percentage of deaths from renal causes (20 percent) (158), while in 1982 Pricereported a renal-related mortality rate of only 14 percent in a long-term follow-up study (involving a large group of civilian SCI patients) (159). More recent studies continue to demonstrate this trend. DeVivo et al., through a process of merging survival data (from the National Database, available collaborative studies, and the Social Security Administration), have shown that kidney and urinarytract diseases account for only a small percentage (3.5 percent) of all deaths in SCI patients (5,160). However, diseases of the urinary system were found to be the most frequent secondary contributing cause of death in SCI patients. Much of the progress in the prevention of renal insufficiency and the reduction of urinary tract disease–related mortality in SCI patients has been achieved through acombination of intensive patient education, the prevention and control of infection, the prevention of reflux, and most importantly, special attention to the maintenance of urine flow and bladder drainage (2,5,160–162).

Pathogenesis

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Tubulointerstitial diseases, characterized by progressive renal insufficiency (with associated pyuria but only minimal proteinuria) have been generallydescribed as the predominant type of kidney disease occurring in SCI patients. However, it has been our experience that moderate to heavy proteinuria, indicative of glomerular disease, is frequently present in SCI patients with moderate to advanced renal insufficiency. It would therefore appear that both tubulointerstitial and glomerular injury are involved in the development of chronic renal failurein patients with longstanding SCI. This concept is consistent with a growing body of evidence indicating that multiple predisposing factors and at least several pathophysiologic processes are likely involved in the genesis of chronic renal insufficiency in patients with longstanding SCI. These include chronic pyelonephritis, nephrolithiasis, obstructive nephropathy, reflux nephropathy,amyloidosis, and hypertensive nephrosclerosis (2,3–6,162–165).

In a study by our group, chronic UTI with pyelonephritis contributed to renal failure in 100 percent of forty-three SCI patients with end-stage renal disease (166), which is similar to the experience reported by other investigators (156). In SCI patients, bacteria may gain easy access to the bladder via an indwelling catheter or as acomplication of intermittent catheterization. Fecal contamination, as well as the dampness associated with absorbent garments, may also increase the frequency and rate of bacterial colonization and subsequent infection. Also, in patients with decubitus ulcers, there is often cross infection between infected pressure sores and the urinary tract (166). Moreover, in SCI patients, UTIs are frequentlyperpetuated by impaired urinary drainage, the presence of urinary calculi, or the use of indwelling catheters (2,45,162,165,166). Furthermore, the combination of active infection and functional obstruction often leads to vesicoureteral reflux, along with a progressive destructive pyelonephritis. In addition to causing tubulointerstitial injury and predisposing to pyelonephritis, reflux nephropathy has...