RESUMO Considera-se que a transfusão de eritrócitos melhora a respiração celular durante o choque séptico. Contudo, seu impacto agudo no transporte e no metabolismo de oxigênio nessa condição ainda é amplamente debatido. O objetivo deste estudo foi avaliar o impacto da transfusão de eritrócitos na microcirculação e no metabolismo do oxigênio em pacientes com sepse e choque séptico. Conduzimos um levantamento nas bases de dados MEDLINE®, Elsevier e Scopus. Incluímos estudos realizados com seres humanos adultos com sepse e choque séptico. Realizamos uma revisão sistemática e metanálise com utilização do modelo de efeitos aleatórios de DerSimonian e Laird. Consideramos significante valor de p < 0,05. Incluíram-se na análise 19 manuscritos, correspondentes a 428 pacientes. As transfusões de eritrócitos se associaram com aumento de 3,7% na média combinada de saturação venosa mista de oxigênio (p < 0,001), diminuição de razão de extração de oxigênio de -6,98 (p < 0,001) e nenhum efeito significante no índice cardíaco (0,02 L/minuto; p = 0,96). Obtiveram-se resultados similares em estudos que incluíram mensurações simultâneas de saturação venosa mista de oxigênio, razão de extração de oxigênio e índice cardíaco. As transfusões de eritrócitos levaram a aumento significante na proporção de pequenos vasos perfundidos (2,85%; p = 0,553), enquanto os parâmetros de oxigenação tissular revelaram aumento significante no índice de hemoglobina tissular (1,66; p = 0,018). Estudos individuais relataram melhoras significantes na oxigenação tissular e nos parâmetros microcirculatórios sublinguais em pacientes com microcirculação alterada na avaliação inicial. A transfusão de eritrócitos pareceu melhorar o metabolismo sistêmico de oxigênio com aparente independência de variações no débito cardíaco. Observaram-se alguns efeitos benéficos para a oxigenação tissular e parâmetros microcirculatórios, em particular em pacientes com alterações iniciais mais graves. São necessários mais estudos para avaliar seu impacto clínico e individualizar as decisões relativas à transfusão.

ABSTRACT Red blood cell transfusion is thought to improve cell respiration during septic shock. Nevertheless, its acute impact on oxygen transport and metabolism in this condition remains highly debatable. The objective of this study was to evaluate the impact of red blood cell transfusion on microcirculation and oxygen metabolism in patients with sepsis and septic shock. We conducted a search in the MEDLINE®, Elsevier and Scopus databases. We included studies conducted in adult humans with sepsis and septic shock. A systematic review and meta-analysis were performed using the DerSimonian and Laird random-effects model. A p value < 0.05 was considered significant. Nineteen manuscripts with 428 patients were included in the analysis. Red blood cell transfusions were associated with an increase in the pooled mean venous oxygen saturation of 3.7% (p < 0.001), a decrease in oxygen extraction ratio of -6.98 (p < 0.001) and had no significant effect on the cardiac index (0.02L/minute; p = 0,96). Similar results were obtained in studies including simultaneous measurements of venous oxygen saturation, oxygen extraction ratio, and cardiac index. Red blood cell transfusions led to a significant increase in the proportion of perfused small vessels (2.85%; p = 0.553), while tissue oxygenation parameters revealed a significant increase in the tissue hemoglobin index (1.66; p = 0.018). Individual studies reported significant improvements in tissue oxygenation and sublingual microcirculatory parameters in patients with deranged microcirculation at baseline. Red blood cell transfusions seemed to improve systemic oxygen metabolism with apparent independence from cardiac index variations. Some beneficial effects have been observed for tissue oxygenation and microcirculation parameters, particularly in patients with more severe alterations at baseline. More studies are necessary to evaluate their clinical impact and to individualize transfusion decisions.

Introducción: La vena yugular interna es anterior o anterolateral a la arteria carótida común en las dos terceras partes de los sujetos estudiados sonográficamente, con la cabeza rotada. Objetivo:Se examinó la asociación de diferentes variables con la ubicación anterior de la vena. Métodos: Las ecografías se realizaron en posición supino, con la cabeza rotada hacia el lado contrario al examinado. Se visualizó transversalmente el tercio proximal del cuello, con un transductor de 7.5 mHz. La relación entre los vasos se describió de acuerdo con la proporción de la arteria cubierta por la vena. Se hicieron comparaciones univariadas con la prueba Chi2 de Pearson y un análisis multivariado de las variables candidatas a afectar las relaciones anatómicas estudiadas Resultados: Se incluyeron 78 individuos, 44 hombres, con edad entre 17-90 años (mediana 64.0, rango= 41-73 años). Se estudió el lado derecho en 75 ocasiones y el izquierdo en 73. La vena se localizó lateral en el 24.3% (IC95%= 17.4-32.2) de los vasos estudiados, anterolateral en el 33.8% (IC95%= 26.2-41.4) y anterior en el 41.9% (IC95%= 33.9-49.8). El análisis multivariado identificó: el grupo etáreo (OR= 3.7, IC95%= 2.1-6.4) y sugiere el lado izquierdo (OR= 1.7, IC95%= 0.8-3.5) y el género masculino (OR= 1.2, IC95%= 0.6-2.7), como variables asociadas con la posición anterior de la vena. Conclusión: La ubicación anterior de la vena yugular interna respecto a la arteria carótida común aumenta gradualmente con la edad. La localización izquierda y el género masculino pueden aumentar adicionalmente esta probabilidad.

Introduction: The internal jugular vein locates anterior or anterolateral to the common carotid artery in two-thirds of the subjects studied by ultrasound when the head is in a rotated position. Aim:To identify variables associated with the anterior location of the internal jugular vein. Methods: Ultrasound examinations were performed with the patients in the supine position, with the head rotated to the opposite side. The proximal third of the neck was visualized transversely with a 7.5-mHz transducer. The relationship between the vessels was described in accordance with the proportion of the artery overlapped by the vein. Univariate comparisons and a multivariate analysis of potential variables that may affect the anatomic relationships were performed. Results: Seventy-eight patients were included, 44 of whom were men. The patients' ages ranged from 17 to 90 years (median= 64.0, interquartile range 41-73). The right and left sides were studied 75 and 73 times, respectively. The vein was located lateral to the artery in 24.3% (95%CI= 17.4-32.2) of the studies, anterolateral in 33.8% (95%CI= 26.2-41.4) and anterior in 41.9% (95%CI 33.9-49.8). The multivariate analysis identified age group (OR= 3.7, 95%CI= 2.1-6.4) and, less significantly, the left side (OR= 1.7, 95%CI 0.8-3.5) and male gender (OR= 1.2, 95%CI= 0.6-2.7) as variables associated with the anterior position of the vein. Conclusion: The anterior position of the internal jugular vein relative to the common carotid artery increases gradually with age. Additionally, left-sided localization and male sex further increased the probability of an anterior position.