Icodextrin dialysis solution improves serum potassium (K) profile and nutritional status in continuous ambulatory peritoneal dialysis (CAPD) patients

Abstract

목적: 기존의 포도당 함유 복막 투석액에 비하여 포도당을 함유하지 않은 icodextrin 투석액이 CAPD 환자의 혈청 칼륨 농도 균형을 유지하는데 더 유리하며 이는 칼륨의 재분포 보다는 환자의 영양상태 개선 및 적절한 칼륨 섭취와 더 관련이 있다는 가설을 검증하고자 한다. 방법: 2006년 1월부터 2007년 12월 동안에 6개월 이상 (평균 81 ± 53 개월) 복막투석을 받고 있는 안정된 환자 255명을 대상으로 하여 혈청 칼륨 농도의 분포와 영양지표 사이의 관계를 조사하였다. Icodextrin을 사용하지 않은 환자군(glucose containing dialysate, GD, 116명)과 icodextrin을 사용한 환자군(icodextrin dialysate, ID, 139명)을 비교하였으며 또한 icodextrin을 사용한 환자군(139명) 내에서 icodextrin 사용전과 후, 임상지표의 변화들을 비교하였다. 한편, 5명의 비당뇨병 CAPD 환자를 대상으로 각각 포도당 함유 복막 투석액 및 icodextrin 투석액 2L에 KCl 40 mEq 를 섞어 복강 내에 급속 부하시킨 후 칼륨의 세포 내 재분포 정도를 측정하였다. 결과: GD 군(116명)과 ID 군(139명) 사이에 저칼륨혈증 (K <3.5 mEq/L)의 빈도는 유사하였으나 (14% vs 13%), ID 군 내에서 icodextrin 사용 전에 비해서 사용 후에 저칼륨혈증의 빈도가 유의하게 낮았다 (19% vs 13%, p＜0.05). 평균 혈청 칼륨 농도는 GD 군보다 ID 군에서 더 높았으며 (4.4 ± 0.6 mEq/L vs 4.6 ± 0.7 mEq/L, p＜0.05), icodextrin 사용 전에 비해 사용 후 더 높았다 (4.4 ± 0.7 mEq/L vs 4.6 ± 0.7 mEq/L, p＜0.05). 전체 환자의 다변량 분석에서 혈청 칼륨 농도는 혈청 알부민과 크레아티닌 농도 및 icodextrin 사용과 양의 상관관계가 있었으며 (p＜0.05), ID 군에서는 혈청 알부민 농도 및 icodextrin 사용기간과 양의 상관관계가 있었다 (p＜0.05). ID 군에서 icodextrin 사용 후 복막투석 기간이 사용 전 기간보다 짧았으나 (22 ± 18 개월 vs 58 ± 52 개월, p＜0.001), icodextin 사용 후에 체질량지수 (23.3 ± 3.3 vs 24.5 ± 3.1), 혈청 total CO2 (26.4 ± 2.8 mEq/L vs 27.5 ± 2.6 mEq/L), 혈청 크레아티닌 (11.1 ± 4.0 mg/dL vs 11.8 ± 4.1 mg/dL), 혈청 알부민 (3.5 ± 0.4 g/dL vs 3.7 ± 0.5 g/dL) 농도가 더 높았다 (p＜0.05). 복강 내 칼륨 부하 실험에서 포도당 함유 복막 투석액을 사용하였을 때보다 icodextrin 을 사용하였을 때 인슐린 농도 변화가 적었으며 (37 ± 12% vs -19 ± 9%, p＜0.05) 세포 내로의 재분포 또한 적었다 (71 ± 5% vs 65 ± 7%, p＜0.05). 그러나 복막을 통한 칼륨 흡수 (75 ± 6% vs 48 ± 5%, p＜0.05) 및 혈청 칼륨 농도의 증가 (0.46 ± 0.1 mEq/L vs 0.18 ± 0.1 mEq/L, p＜0.05) 또한 더 적었다. 결론: 기존의 포도당 함유 복막 투석액에 비하여 icodextrin 투석액 사용이 CAPD 환자에서 빈번한 저칼륨혈증 발생 예방에 도움이 되며, 이는 칼륨의 재분포 보다는 영양상태 개선 및 적절한 칼륨 섭취와 관련이 있을 것으로 추정된다.; Objectives: The objective of this study is to ascertain whether the optimal potassium (K) balance could be better maintained in continuous ambulatory peritoneal dialysis (CAPD) patients using non-glucose containing icodextrin dialysate (ID) compared to those using conventional glucose containing dialysate (GD) and to evaluate whether increased cellular K redistribution associated with icodextrin use could be the major factor responsible for the better maintenance of potassium balance. Methods: This observational study was performed to evaluate serum potassium (K) profile and its relation to nutritional markers in a total 255 stable end stage renal disease patients treated with CAPD for more than 6 months, 116 patients on GD and 139 on ID, during a 2-year study period (Jan. 2006-Dec. 2007). For each patients, mean values of serum level of K, albumin, creatinine, and total CO2 for the last 3 consecutive months during the study period were obtained. In 139 patients who were using icodextrin solution for overnight dwell (ID), the mean values of serum K, albumin, creatinine, phosphorus, cholesterol and BUN for 3 consecutive months just prior to icodextrin use (Pre-ID) and similarly obtained mean values at the end of study period after icodextrin use (Post-ID) were compared. Also, the degree of the intracellular K redistribution was evaluated with an acute load of 40 mEq of KCl mixed to 2 L of dialysate (either GD or ID) on overnight fasting in 5 stable non-diabetic CAPD patients. Each subjects underwent this test with both GD and ID performed at one-week interval. Results: The frequency of hypokalemia (< 3.5 mEq/L) was similar between patients on GD and on ID (14% vs 13%), but it was significantly lower in Post-ID than in Pre-ID (13% vs 19%, p＜0.05). The mean serum K level was higher in ID than in GD patients (4.6 ± 0.7 mEq/L vs 4.4 ± 0.6 mEq/L, p＜0.05). Similarly, the mean serum K level of Post-ID was higher than that of Pre-ID (4.6 ± 0.7 mEq/L vs 4.4 ± 0.7 mEq/L, p＜0.05). In multivariate analysis, serum K levels were positively correlated with serum albumin, serum creatinine, and icodextrin-use (p＜0.05) in all patients. In ID group, serum K levels were correlated with serum albumin and duration of icodextrin use (p＜0.05). Body mass index (24.5 ± 3.1 vs 23.3 ± 3.3), serum total CO2 (27.5 ± 2.6 mEq/L vs 26.4 ± 2.8 mEq/L), serum creatinine (11.8 ± 4.1 mg/dL vs 11.1 ± 4.0 mg/dL), and serum albumin (3.7 ± 0.5 g/dL vs 3.5 ± 0.4 g/dL) in Post-ID were significantly higher than those in Pre-ID (p <0.05), whereas duration of CAPD was significantly longer in Pre-ID (58 ± 52 months vs 22 ± 18 months, p＜0.001). In the acute intraperitoneal K-load test, the change of insulin from the basal values was much less in ID compared to that in GD (-19 ± 9% vs 37 ± 12%, P＜0.05), which was also accompanied by less increment in the calculated intracellular K redistribution in ID (65 ± 7% vs 71 ± 5%, P＜0.05). However, the degree of acute serum K change was significantly less in ID than GD (0.18 ± 0.1 mEq/L vs 0.46 ± 0.1 mEq/L , p＜0.05) with less intraperitoneal K absorption (48 ± 5% vs 75 ± 6%, p＜0.05). Conclusion: These overall data suggest that icodextrin dialysate for overnight dwell has the advantage of preventing hypokalemia compared to conventional glucose containing dialysate. This improved chronic K balance in CAPD patients on icodextrin could be related to enhanced nutritional status possibly associated with adequate dietary K intake (external balance) rather than to transcellular K redistribution (internal balance).