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OBJECTIVE: To investigate whether the respiratory variation of the inferior vena cava diameter (∆DIVC) and right internal jugular vein diameter (∆DRIJ) are correlated in mechanically ventilated patients. METHODS: This study was a prospective clinical analysis in an intensive care unit at a university hospital. Thirty-nine mechanically ventilated patients with hemodynamic instability were included. ∆DIVC and ∆DRIJ were assessed by echography. Vein distensibility was calculated as the ratio of (A) Dmax--Dmin/Dmin and (B) Dmax--Dmin/ mean of Dmax--Dmin and expressed as a percentage. RESULTS: ∆DIVC and ∆DRIJ were correlated by both methods: (A) r = 0.34, p = 0.04 and (B) r = 0.51, p = 0.001. Using 18% for ∆DIVC, indicating fluid responsiveness by method (A), 16 patients were responders and 35 measurements showed agreement (weighted Kappa = 0.80). The area under the ROC curve was 0.951 (95%CI 0.830 - 0.993; cutoff = 18.92). Using 12% for ∆DIVC, indicating fluid responsiveness by method (B), 14 patients were responders and 32 measurements showed agreement (weighted Kappa = 0.65). The area under the ROC curve was 0.903 (95%CI 0.765 - 0.973; cut-off value = 11.86). CONCLUSION: The respiratory variation of the inferior vena cava and the right internal jugular veins are correlated and showed significant agreement. Evaluation of right internal jugular vein distensibility appears to be a surrogate marker for inferior vena cava vein distensibility for evaluating fluid responsiveness.

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RESUMOObjetivo:Investigar se a variação respiratória no diâmetro da veia cava inferior (ΔDVCI) e no diâmetro da veia jugular interna direita (ΔDVJID) se correlacionam em pacientes submetidos à ventilação mecânica.Métodos:Estudo clínico prospectivo realizado em uma unidade de terapia intensiva de um hospital universitário. Foram incluídos 39 pacientes mecanicamente ventilados e com instabilidade hemodinâmica. Os valores da variação do diâmetro da veia cava inferior e da variação do diâmetro da veia jugular interna direita foram avaliados por meio de ecografia. A distensibilidade da veia foi calculada como a razão de (A) Dmin - Dmax/Dmin e (B) Dmax - Dmin/média de Dmax - Dmin, e expressa como porcentagem.Resultados:Com ambos os métodos, observou-se correlação entre a variação do diâmetro da veia cava inferior e a variação do diâmetro da veia jugular interna direita: (A) r = 0,34, p = 0,04 e (B) r = 0,51, p = 0,001. Utilizando o ponto de corte de 18% para indicar responsividade a fluidos na variação do diâmetro da veia cava inferior, pelo o método (A), 16 pacientes foram considerados responsivos e 35 medições mostraram concordância (Kappa ponderado = 0,80). A área sob a curva ROC foi de 0,951 (IC95% 0,830 - 0,993; valor de corte = 18,92). Usando 12% como ponto de corte para a variação do diâmetro da veia cava inferior para indicar capacidade de resposta a fluidos, pelo método (B), 14 pacientes foram responsivos e 32 medições mostraram concordância (Kappa ponderado = 0,65). A área sob a curva ROC foi de 0,903 (IC95% 0,765 - 0,973; valor de corte = 11,86).Conclusão:As variações respiratórias nas dimensões da veia cava inferior e da veia jugular interna direita se correlacionaram e mostraram concordância significativa. Avaliação da distensibilidade da veia jugular interna direita parece ser uma alternativa à distensibilidade da veia cava inferior para avaliar a responsividade a fluidos.

ABSTRACTObjective:To investigate whether the respiratory variation of the inferior vena cava diameter (∆DIVC) and right internal jugular vein diameter (∆DRIJ) are correlated in mechanically ventilated patients.Methods:This study was a prospective clinical analysis in an intensive care unit at a university hospital. Thirty-nine mechanically ventilated patients with hemodynamic instability were included. ∆DIVC and ∆DRIJ were assessed by echography. Vein distensibility was calculated as the ratio of (A) Dmax - Dmin/Dmin and (B) Dmax - Dmin/ mean of Dmax - Dmin and expressed as a percentage.Results:∆DIVC and ∆DRIJ were correlated by both methods: (A) r = 0.34, p = 0.04 and (B) r = 0.51, p = 0.001. Using 18% for ∆DIVC, indicating fluid responsiveness by method (A), 16 patients were responders and 35 measurements showed agreement (weighted Kappa = 0.80). The area under the ROC curve was 0.951 (95%CI 0.830 - 0.993; cutoff = 18.92). Using 12% for ∆DIVC, indicating fluid responsiveness by method (B), 14 patients were responders and 32 measurements showed agreement (weighted Kappa = 0.65). The area under the ROC curve was 0.903 (95%CI 0.765 - 0.973; cut-off value = 11.86).Conclusion:The respiratory variation of the inferior vena cava and the right internal jugular veins are correlated and showed significant agreement. Evaluation of right internal jugular vein distensibility appears to be a surrogate marker for inferior vena cava vein distensibility for evaluating fluid responsiveness.

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Central venous blood oxygen saturation (ScvO2) is an important monitoring index of fluid resuscitation. However, monitoring of ScvO2 is not continuous and invasive. Near infrared spectroscopy (NIRS) is an optical technology for the noninvasive detection of hemodynamic changes, with advantages of being real-time, continuous, low-cost, and portable. The present study aimed to determine whether a correlation exists between the tissue blood oxygen saturation in the internal jugular venous area (StO2) data obtained with NIRS and the ScvO2 and whether these two quantities are equivalent. Data were collected from 13 patients. We used ultrasound to locate the placement site for the NIRS light source outside the internal jugular vein. Meanwhile, a sample for blood gas analysis was obtained through the central venous catheter. A correlation analysis between the StO2 and ScvO2 of 13 samples was performed (Pearson correlation coefficient), suggesting a high correlation between them (r = 0.906, StO2 =1.0018 ScvO2 +2.8524). Bland-Altman analysis was also performed between the StO2 and ScvO2. Results were as follows: 100% of monitored points fell within the range of the mean ± 1.96 SD of the difference between the StO2 and ScvO2; range of the mean ± 1.96 SD of the difference between the StO2 and ScvO2 was 3 ± 10.2; confidence interval of the difference between the StO2 and ScvO2 was -7.2 to 13.2%. The StO2 monitored with NIRS correlated highly with the ScvO2 measured in the internal jugular vein. Therefore, the StO2 can be used for directing clinical treatment with further research.

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Neo-intima development and atherosclerosis limit long-term vein graft use for revascularization of ischaemic tissues. Using a rat model, which is technically less challenging than smaller rodents, we provide evidence that the temporal morphological, cellular, and key molecular events during vein arterialization resemble the human vein graft adaptation. Right jugular vein was surgically connected to carotid artery and observed up to 90 days. Morphometry demonstrated gradual thickening of the medial layer and important formation of neo-intima with deposition of smooth muscle cells (SMC) in the subendothelial layer from day 7 onwards. Transmission electron microscopy showed that SMCs switch from the contractile to synthetic phenotype on day 3 and new elastic lamellae formation occurs from day 7 onwards. Apoptosis markedly increased on day 1, while alpha-actin immunostaining for SMC almost disappeared by day 3. On day 7, cell proliferation reached the highest level and cellular density gradually increased until day 90. The relative magnitude of cellular changes was higher in the intima vs. the media layer (100 vs. 2 times respectively). Cyclin-dependent kinase inhibitors (CDKIs) p27(Kip1) and p16(INKA) remained unchanged, whereas p21(Cip1) was gradually downregulated, reaching the lowest levels by day 7 until day 90. Taken together, these data indicate for the first time that p21(Cip1) is the main CDKI protein modulated during the arterialization process the rat model of vein arterialization that may be useful to identify and validate new targets and interventions to improve the long-term patency of vein grafts.

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INTRODUCTION: Catheterization of the jugular bulb is of great value in the study of cerebral metabolism, since it permits diagnosis of episodes of hypoxia and cerebral ischaemia. OBJECTIVES: To determine the frequency of the appearance of episodes of desaturation and cerebral ischaemia, whether these were simultaneous and their relation to the mortality in an intensive care unit (ICU). PATIENTS AND METHODS: We studied 21 neurocritical patients, recording the following data: age, sex, diagnosis and state at the time of discharge from the ICU (alive or dead). In the group of patients in whom the jugular bulb had been catheterised we also recorded: the side cannulated, complications, SyO2, cerebral lactate oxygen index and modified cerebral lactate oxygen. RESULTS: In 57% of the patients we catheterised the jugular bulb and in 50% of them at least one episode of desaturation was recorded, and cerebral ischaemia in 42%. Only one patient had simultaneous desaturation and cerebral ischaemia. Of the six patients in whom desaturation was detected, 5 died in the ICU (83.3%). The mortality of patients with ischaemia was only 40%. 40% of the patients with head injuries were monitored and 50% of the non monitored patients had head injuries. CONCLUSIONS: Episodes of desaturation are frequent in neurocritical patients and are associated with increased mortality. Recordings of lactate are not useful at present in the diagnosis of cerebral ischaemia.

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