Comparison of lactate values obtained from different sites and their clinical significance in patients with severe sepsis Comparação de valores de lactato obtidos em diferentes sítios e sua importância clínica em pacientes com sepse grave

CONTEXT AND OBJECTIVE: The ideal site for lactate collection has not been clearly established. This study aimed to evaluate associations between lactate levels in arterial blood (Lart), peripheral venous blood (Lper) and central venous blood (Lcen) in patients with severe sepsis or septic shock. DESIGN AND SETTING: Cross-sectional analytical study in an tertiary university hospital. METHOD: Samples from patients with a central venous catheter and from healthy volunteers (control group) were collected. Blood was drawn simultaneously for measurements of Lart, Lper and Lcen, and the first sample was collected less than 24 hours after the onset of organ dysfunction. The results were analyzed using Pearson correlation, Bland-Altman and McNemar tests. RESULTS: A total of 238 samples were collected from 32 patients. The correlation results were r = 0.79 (P < 0.0001) for Lart/Lper and r = 0.84 (P < 0.0001) for Lart/Lcen. Bland-Altman showed large limits of agreement: -3.2 ± 4.9 (-12.8 to 6.4) and -0.8 ± 5.9 (-12.5 to 10.8), for Lper and Lcen respectively. In the control group, there was greater correlation (r = 0.9009, P = 0.0004) and agreement: -0.7 ± 1.2 (-3.1 to 1.7). Regarding clinical intervention, there was good agreement between Lart/Lcen (96.3%; three disagreements), with worst results for Lart/Lper (87.0%) with 10 cases of disagreement (P = 0.04). In eight patients (80.0%) Lper was higher than Lart. CONCLUSION: Lcen, and not Lper, can replace Lart with good correlation and clinical agreement. Lper tends to overestimate Lart, thus leading to unnecessary therapeutic interventions. RESUMO CONTEXTO E OBJETIVO: O sitio ideal de coleta do lactato nao esta claramente estabelecido. Este estudo objetivou avaliar a associacao dos valores de lactato do sangue arterial (Lart), venoso periferico (Lper) e venoso central (Lcen) em pacientes com sepse grave ou choque septico. TIPO DE ESTUDO E LOCAL: Estudo transversal analitico em hospital universitario terciario. METODOS: Amostras de pacientes com cateter venoso central e voluntarios sadios (grupo controle) foram coletadas. O sangue foi obtido de forma simultânea para medida do Lart, Lper and Lcen, sendo a primeira amostra coletada no maximo 24 horas apos o inicio da disfuncao orgânica. Resultados foram analisados usando a correlacao de Pearson, os testes de Bland-Altman e McNemar. RESULTADOS: Um total de 238 amostras foi coletado em 32 pacientes. Resultados da correlacao: r = 0.79 (P < 0,0001) para Lart/Lper e r = 0.84 (P < 0,0001) para Lart/Lcen. Bland-Altman mostrou largos limites de concordância, -3.2 ± 4.9 (-12.8 to 6.4) and -0.8 ± 5.9 (-12.5 to 10.8), para Lper e Lcen, respectivamente. No grupo controle, houve uma maior correlacao (r = 0.9009, P = 0,0004) e concordância: -0.7 ± 1.2 (-3.1 to 1.7). No que se refere a intervencao clinica, houve boa concordância Lart/Lcen (96.3%, tres nao concordantes), com resultados piores encontrados para Lart/Lper (87.0%) com 10 casos nao concordantes (P = 0,04). Em oito pacientes (80.0%) Lper foi mais elevado que Lart. CONCLUSAO: Lcen, e nao Lper, pode substituir Lart com boa correlacao e concordância clinica. Lper tende a superestimar Lart, assim levando a intervencoes terapeuticas desnecessarias.