Fluid Management and Edema Control Flashcards

In peritoneal dialysis, osmotic fluid removal is driven by which agent in the dialysate, and what is the primary nutritional complication of its use?

Answer: Glucose (dextrose) — absorbed from the peritoneal cavity causing increased caloric intake, hyperglycemia (especially in diabetics), hyperlipidemia, and obesity

PD dialysate uses glucose as the osmotic agent. Between 200–800 kcal/day is absorbed from dialysate glucose, contributing to hyperglycemia (in diabetic and non-diabetic patients), hypertriglyceridemia, and obesity — significant nutritional complications unique to PD.

A peritoneal dialysis patient switches from CAPD to automated peritoneal dialysis (APD) with one long 'wet' daytime dwell. How does this change fluid management and nutritional considerations?

Answer: APD with icodextrin for the daytime dwell allows more consistent ultrafiltration; icodextrin (large polysaccharide) is metabolized to maltose and may affect glucose monitoring using certain glucometers — clinical dietitian must counsel on this interaction

APD patients often use icodextrin for the long daytime dwell. Icodextrin metabolites (maltose, maltotriose) interfere with glucose oxidase-based glucometers, causing falsely elevated glucose readings. This affects diabetes management decisions and is a critical safety counseling point for the dietitian.

For a CKD patient with resistant edema being treated with IV furosemide, the dietitian notes the patient is consuming 5 g/day of sodium. How much sodium reduction is needed to achieve < 2.3 g/day, and what is the most practical first step?

Answer: A reduction of 2.7 g/day is needed; start by eliminating added salt at the table and during cooking (typically ~1.5–2 g/day reduction)

5 g/day - 2.3 g/day target = 2.7 g/day reduction needed. Eliminating discretionary salt (table salt and cooking salt) typically removes 1.5–2 g/day. The remaining ~0.7–1.2 g reduction requires targeting processed/packaged foods, which contain ~80% of dietary sodium.

A hemodialysis patient reports drinking 2.5 L of fluid daily despite a 1.5 L/day restriction. On dietary assessment, the dietitian finds that the patient is not counting soup, yogurt, ice cream, and frozen fruit as 'fluids.' What is the appropriate educational intervention?

Answer: Educate the patient that ALL foods that are liquid at room temperature (soups, gelatin, ice cream, pudding, yogurt) AND high-water-content foods (watermelon, frozen fruit) must be counted as part of the fluid allowance

Any food that is liquid at room temperature (ice melts, gelatin melts, soups, ice cream) counts as fluid intake. Many patients incorrectly believe only beverages count. Hidden fluid sources routinely cause patients to significantly exceed prescribed limits.

Bioelectrical impedance analysis (BIA) or bioimpedance spectroscopy (BIS) is used to assess fluid status in dialysis patients. When should BIA/BIS be performed for the MOST accurate measurement of dry weight?

Answer: Immediately after dialysis (post-HD), when the patient is at or near their dry weight/target weight — minimizing the fluid excess that confounds measurement

BIA/BIS measures body fluid compartments based on electrical impedance. Post-dialysis measurement (after achieving target/dry weight) provides the most accurate baseline body composition assessment, as the pre-dialysis fluid excess would overestimate extracellular fluid and underestimate dry body mass.

A CKD Stage 5 (non-dialysis) patient has developed hyponatremia (Na 128 mEq/L) and gross edema. Lab confirms low urine sodium (<20 mEq/L). What does low urine sodium indicate in this context, and what dietary intervention is appropriate?

Answer: Low urine sodium indicates avid renal sodium retention (RAAS/aldosterone activation, reduced GFR); the appropriate intervention is NOT sodium supplementation but sodium restriction combined with fluid restriction, as more sodium would worsen edema further

In edematous hyponatremia, low urine sodium reflects avid renal sodium reabsorption (kidneys holding onto sodium to maintain perceived volume). This is dilutional hyponatremia — total body sodium is ELEVATED (causing edema), but serum sodium is low because water retention exceeds sodium retention. Treatment: sodium + fluid restriction, not sodium supplementation.