体液总量估算方法对Kt/V值的影响

摘要

目的 比较使用体积法(将测量出的体液总量带入可变体积尿素动力学模型变形式)和体质量法(可变体积尿素动力学模型法)计算Kt/V的结果,探究2种方法所得结果的差异及其影响因素.方法 选取2016年10~11月于北京大学人民医院进行血液透析的患者,收集其年龄、性别、原发病、透析龄、透前体质量、透析前透析后血尿素值、透析前体液总量、肌肉组织含量、脂肪组织含量等临床资料,使用配对t检验比较体积法和体质量法计算的Kt/V值,将2组患者差值比率以2%为界将患者为2组(无差异组和有差异组),比较2组患者各项指标的差异,并使用线性回归分析2组结果差异的影响因素.结果 本研究共纳入58例患者,其中男性占58.621%(34/58),平均年龄(57.603±14.788)岁.采用体积法和体质量法计算Kt/V有统计学差异(1.591±0.401比1.557±0.390,t=-9.154,P<0.001),2种方法计算结果呈正相关(r=0.998,P<0.001).将2组结果差值比率以2%为界分为无差异组和有差异组后,发现2组患者男性比例(81.481%比38.710%,χ2=10.884,P=0.001)、相对脂肪组织含量[(42.170±10.898)%比(56.765±6.808)%,t=6.200,P<0.001]、相对肌肉组织含量[(58.428±9.555%)比(44.729±6.625)%,t=-6.410,P<0.001]、总体液量[(33.722±6.752)L比(27.568±5.378)L,t=-3.861,P<0.001]有统计学差异,而年龄[(57.111±16.078)岁比(58.032±13.824)岁,t=0.235,P=0.815]、透析后体质量(67.663±13.52)kg比(66.461±11.344)kg,t=-0.368,P=0.714)等指标无统计学差异.进一步分析发现男性患者相对女性,其2组方法的Kt/V结果差值较大(0.0202±0.0166比0.0538±0.0301,t=-5.451,P<0.001),而相对脂肪组织含量(r=0.270,P<0.001)、脂肌比(r=0.054,P<0.001)与结果差值呈正相关,相对肌肉组织含量与结果差值呈负相关(r=-0.209,P<0.001).结论 采用体积法和采用体质量法计算Kt/V有统计学差异,同一患者使用体积法比使用体质量法计算得Kt/V值普遍要大,其结果差值受性别、相对脂肪组织含量、相对肌肉组织含量和脂肌比影响,但结果差值较小,无临床意义.%Objective To compare the difference between Kt/V values calculated by two methods (vol-ume method which puts total body water into the variant form of Daugirdas''second generation equation, and weight method based on Daugirdas''second generation equation) and to investigate the impact factors contrib-uting to the difference. Methods The outpatients dialyzed at our department from September 2016 to No-vember 2016 were enrolled. The clinical indices including age, gender, predialysis weight, predialysis and postdialysis plasma urea, predialysis total body water, lean tissue mass (LTM) and adipose tissue mass (ATM) and other clinical data were collected. The Kt/V values calculated by volume method and weight method were compared using paired-t test. Using the difference ratio (the difference of two values divided by the Kt/V val-ue calculated by volume method) of 2%as the boundary, we divided the participants into two groups:non-dif-ference group and difference group. Clinical indices were compared between the two groups. Linear regres-sion was applied to analyze the potential impact factors of the difference between Kt/V values calculated from the two methods. Results A total of 58 outpatients with an average age of 57.603±14.788 years old were en-rolled, and 58.621%(34/58) of them were males. The Kt/V values calculated by volume method and weight method were significantly different (1.591 ± 0.401 vs. 1.557 ± 0.390, t=-9.154, P<0.001) and were positively correlated (r=0.998, P<0.001). Male ratio (81.481% vs. 38.710%, χ2=10.884, P=0.001), ATM/weight (42.170±10.898%vs. 56.765±6.808%, t=6.200, P<0.001), LTM/weight (58.428±9.555%vs. 44.729±6.625%, t=-6.410, P<0.001) and total body water (33.722±6.752 vs. 27.568±5.378, t=-3.861, P<0.001) were signifi-cantly different between non-difference group and difference group, while age (57.111 ± 16.078 vs. 58.032 ± 13.824, t=0.235, P=0.815), postdialysis weight (67.663±13.52 vs. 66.461±11.344, t=-0.368, P=0.714) had no differences between the two groups. Furthermore, we found male patients had bigger difference between Kt/V values calculated by the two methods (0.0202±0.0166 vs. 0.0538±0.0301, t=-5.451, P<0.001). Linear regres-sion analysis showed that ATM/weight (r=0.2705, P<0.001) and ATM/LTM (r=0.0542, P<0.001) were posi-tively correlated with the difference, while LTM/weight was negatively correlated with the difference (r=-0.2091, P<0.001). Conclusion There was statistically significant difference between Kt/V values calculated by volume method and weight method, and the Kt/V value calculated by volume method was always higher than that calculated by weight method in the same patient. The difference between Kt/V values calculated by the two methods was influenced by sex, LTM/weight, ATM/weight and ATM/LTM.