Park M, Taniguchi L U, Noritomi D T, Libório A B, Maciel A T, Cruz-Neto L M
Departamento de Emergência, Unidade de Terapia Intensiva, Universidade de São Paulo, Brasil.
Braz J Med Biol Res. 2008 Mar;41(3):241-9. doi: 10.1590/s0100-879x2006005000199. Epub 2007 Dec 11.
The aims of this study were to determine whether standard base excess (SBE) is a useful diagnostic tool for metabolic acidosis, whether metabolic acidosis is clinically relevant in daily evaluation of critically ill patients, and to identify the most robust acid-base determinants of SBE. Thirty-one critically ill patients were enrolled. Arterial blood samples were drawn at admission and 24 h later. SBE, as calculated by Van Slyke's (SBE VS) or Wooten's (SBE W) equations, accurately diagnosed metabolic acidosis (AUC = 0.867, 95%CI = 0.690-1.043 and AUC = 0.817, 95%CI = 0.634-0.999, respectively). SBE VS was weakly correlated with total SOFA (r = -0.454, P < 0.001) and was similar to SBE W (r = -0.482, P < 0.001). All acid-base variables were categorized as SBE VS <-2 mEq/L or SBE VS <-5 mEq/L. SBE VS <-2 mEq/L was better able to identify strong ion gap acidosis than SBE VS <-5 mEq/L; there were no significant differences regarding other variables. To demonstrate unmeasured anions, anion gap (AG) corrected for albumin (AG A) was superior to AG corrected for albumin and phosphate (AG A+P) when strong ion gap was used as the standard method. Mathematical modeling showed that albumin level, apparent strong ion difference, AG A, and lactate concentration explained SBE VS variations with an R(2) = 0.954. SBE VS with a cut-off value of <-2 mEq/L was the best tool to diagnose clinically relevant metabolic acidosis. To analyze the components of SBE VS shifts at the bedside, AG A, apparent strong ion difference, albumin level, and lactate concentration are easily measurable variables that best represent the partitioning of acid-base derangements.
本研究的目的是确定标准碱剩余(SBE)是否是诊断代谢性酸中毒的有用工具,代谢性酸中毒在重症患者的日常评估中是否具有临床相关性,并确定SBE最可靠的酸碱决定因素。纳入了31例重症患者。入院时和24小时后采集动脉血样本。通过范斯莱克(SBE VS)或伍滕(SBE W)方程计算的SBE能准确诊断代谢性酸中毒(AUC分别为0.867,95%CI = 0.690 - 1.043和AUC = 0.817,95%CI = 0.634 - 0.999)。SBE VS与总序贯器官衰竭评估(SOFA)评分呈弱相关(r = -0.454,P < 0.001),且与SBE W相似(r = -0.482,P < 0.001)。所有酸碱变量分为SBE VS < -2 mEq/L或SBE VS < -5 mEq/L。SBE VS < -2 mEq/L比SBE VS < -5 mEq/L更能识别强离子间隙酸中毒;其他变量无显著差异。为了显示未测定阴离子,当以强离子间隙作为标准方法时,校正白蛋白后的阴离子间隙(AG A)优于校正白蛋白和磷酸盐后的阴离子间隙(AG A+P)。数学模型显示,白蛋白水平、表观强离子差、AG A和乳酸浓度可解释SBE VS变化,R(2) = 0.954。截断值为< -2 mEq/L的SBE VS是诊断临床相关代谢性酸中毒的最佳工具。为了在床边分析SBE VS变化的组成部分,AG A、表观强离子差、白蛋白水平和乳酸浓度是易于测量的变量,最能代表酸碱紊乱的分配情况。