Prescription principles:
When intraperitoneal fill volume is scaled to weight, the child receives less dialysate in proportion to membrane surface area. Children tend to equilibrate and absorb glucose quickly which makes them appear to be high transporters. If intraperitoneal fill volume is scaled to body surface area (BSA), this functional hyperpermeability disappears31. The target range for the exchange volume of patients older than 2 years is approximately 1100 mL/m2 BSA; however, the initial prescribed volume may be somewhat lower in smaller infants (~600 to 800 mL/m2 BSA). A stepwise increase in volume as tolerated by the patient usually is possible starting at 10 milliliters per kilogram per exchange. At these low fill volumes, it is common to have reabsorption; therefore, it is useful to use a higher dextrose concentration such as 2.5% or 4.25%31. The optimal intraperitoneal volume (IPV) range for pediatrics is 600-1400 milliliters per meter squared of body surface area31. IPV is individualized to achieve target goals and recommendations suggest a lower range in CAPD due to higher intraperitoneal pressure in the upright position. When patient status requires early catheter use, lower volumes, such as 300 milliliters per meter square of body surface area32 are necessary to reduce the risk of catheter leakage. When volumes are determined by body weight, the volume is often 30 to 50 milliliters per kilogram of body weight per exchange in children and 10 to 30 milliliters per kilogram of body weight per exchange in neonates17,33. The method for measuring intraperitoneal pressure has been described in several publications and can easily be measured at bedside31. The dialysis prescription should be individualized for each patient. Large fill volumes should be avoided as they may compromise respiratory and cardiac function, as well as potentially result in hernia formation and catheter leakage30. When using gravity cyclers, a cycler in too high of a position may result in aortic compression due to rapid instillation of dialysate.
Pediatric peritoneal dialysis adequacy
KDOQI has not published specific pediatric adequacy guidelines and thus adult recommendations are followed. Regularly repeated measurement of total solute clearance is necessary to achieve and maintain dialysis adequacy. Ideally, 24-hour collections of both urine and dialysate fluid should be obtained 3 times per year or whenever significant changes in the patient’s clinical status has influenced dialysis performance30,34. Examples of significant change may be a decrease in urine output or severe and/or repeated peritonitis. The clinical use of a target total weekly Kt/V of greater than or equal to 1.7 and a total weekly creatinine clearance of greater than or equal to 60 liters per 1.73 meters squared is suggested to achieve dialysis adequacy in children receiving CAPD34. Note the minimum Kt/V is 1.7 (peritoneal and residual renal function) as long as the patient is thriving. This value was derived following data obtained from the ADEMEX35 and Hong Kong36 studies. In the ADEMEX study, (total average Kt/Vurea of 1.8 versus 2.27) 2 groups of patients had identical survival, indicating no benefit on survival for greater small-molecule peritoneal clearance and confirming the benefit of residual kidney function on survival. However, the group randomized to the lower prescription had slightly, but significantly, more deaths from congestive heart failure (CHF), more deaths ascribed to uremia and hyperkalemia. The Hong Kong study compared total Kt/Vurea values of 1.5 to 1.7, 1.7 to 2.0, and greater than 2.0 in CAPD patients. There were no differences in patient survival in the 3 groups. The original recommendation of Kt/Vurea > 2 arose from CANUSA study37.
Principles of the pediatric Peritoneal Equilibration Test (PET)
Peritoneal transport characteristics in children differ from adults10, 13, 14, and 15. It is known that the peritoneal area in infants per unit weight is twice that of the adult. Early studies appeared to indicate that infants and small children had high transport, but it is now recognized that this assumption was a result of not scaling the exchange volume to body surface area. Equilibration curves specific to children have been developed14. The typical pediatric PET14,15 requires a fill volume between 1100-1200 milliliters per meter squared with 2.5% dextrose. Five milliliter samples are taken at 0, 30, 60, 120, and 240 minutes and each specimen is sent for glucose, creatinine, and urea values. Note the increased number of samples compared to the adult PET. This process is time consuming and it is helpful to have toys, puzzles, and movies in the clinic to entertain the child14, 15.
With teens, one may be able to use a standard adult PET if the teen can accommodate a 2 Liter fill.
References:
10. Fischbach M, Mengus L, Birmele B, Hamel G, Simeoni U, Geisert J. Solute equilibration curves, crossing time for urea and glucose during peritoneal dialysis: A function of age in children. Adv Perit Dial 7:262-265, 1991
13. Geary DF, Harvey EA, MacMillan JH, Goodman Y, Scott M, Balfe JW. The peritoneal equilibration test in children. Kidney Int 42:102-105, 1992
14. Schaefer F, Langenbeck D, Heckert KH, Scharer K, Mehls O. Evaluation of peritoneal solute transfer by the peritoneal equilibration test in children. Adv Perit Dial 8:410-415, 1992
15. Warady BA, Alexander SR, Hossli S, Vonesh E, Geary D, Watkins S, Salusky IB, and Kohaut EC. Peritoneal membrane transport function in children receiving long-term dialysis. J Am Soc Nephrol 7:2385-2391, 1996
17. Daschner M, Schaefer F: Emergency dialysis in neonatal metabolic crises. Adv Ren Repla Thera 9:63-69, 2002
30. Avner ED, Harmon WE, Niaudet P. Section XI: Chronic Renal Failure. Chapter 70: Peritoneal Dialysis. In Pediatric Nephrology. 5th Ed. Philadelphia:Lippincott Williams & Wilkins, 2004:1375-1394
31. Fishbach M, Terzie J, Menouer S, Haraldsson B: Optimal volume prescription for children on peritoneal dialysis. Perit Dial Int 20:603-606, 2000
32. Schafer F: Prescribing and Monitoring Peritoneal Dialysis in Pediatric Patients. 22nd Annual Conference on Dialysis, March 3, 2002
33. Fischbach M, Terzie J, Geisert J. Prescription of Peritoneal Dialysis: CAPD, CCPD, COPD, IPD or TPD. In: Fine RN, Alexander SR, Warady BA, eds. CAPD/CCPD in Children, 2nd ed. Boston/Drodrecht/London: Kluwer Academic Publishers. 1998:247-261
34. NKF-K/DOQI. Clinical practice guidelines for peritoneal dialysis adequacy. New York: National Kidney Foundation, 2001
35. Paniagua R, Amato D, Vonesh E, Correa–Rotter R, Ramos A, Moran J, et al., for the Mexican Nephrology Collaborative Study Group. Effects of increased peritoneal clearances on mortality rates in peritoneal dialysis: ADEMEX, a prospective, randomized, controlled trial. J Am Soc Nephrol 13:1307–1320, 2002
36. Szeto CC, Wong TY, Chow KM, Leung CB, Law MC, Wang AY, et al. Impact of dialysis adequacy on the mortality and morbidity of anuric Chinese patients receiving continuous ambulatory peritoneal dialysis. J Am Soc Nephrol 12:355–360, 2001
37. Churchill DN, Taylor DW, Keshaviah PR for the CANUSA Peritoneal Study Group: Adequacy of dialysis and nutrition in continuous peritoneal dialysis: Association with clinical outcomes. J Am Soc Nephrol 7:198-207, 1996
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