The antioxidant effect of preischemic dexmedetomidine in a rat model: increased expression of Nrf2/HO-1 via the PKC pathway

Abstract Background The precise underlying mechanism of antioxidant effects of dexmedetomidine-induced neuroprotection against cerebral ischemia has not yet been fully elucidated. Activation of Nuclear factor erythroid 2-related factor (Nrf2) and Heme Oxygenase-1 (HO-1) represents a major antioxidant-defense mechanism. Therefore, we determined whether dexmedetomidine increases Nrf2/HO-1 expression after global transient cerebral ischemia and assessed the involvement of Protein Kinase C (PKC) in the dexmedetomidine-related antioxidant mechanism. Methods Thirty-eight rats were randomly assigned to five groups: sham (n = 6), ischemic (n = 8), chelerythrine (a PKC inhibitor; 5 mg.kg-1 IV administered 30 min before cerebral ischemia) (n = 8), dexmedetomidine (100 µg.kg-1 IP administered 30 min before cerebral ischemia (n = 8), and dexmedetomidine + chelerythrine (n = 8). Global transient cerebral ischemia (10 min) was applied in all groups, except the sham group; histopathologic changes and levels of nuclear Nrf2 and cytoplasmic HO-1 were examined 24 hours after ischemia insult. Results We found fewer necrotic and apoptotic cells in the dexmedetomidine group relative to the ischemic group (p< 0.01) and significantly higher Nrf2 and HO-1 levels in the dexmedetomidine group than in the ischemic group (p< 0.01). Additionally, chelerythrine co-administration with dexmedetomidine attenuated the dexmedetomidine-induced increases in Nrf2 and HO-1 levels (p< 0.05 and p< 0.01, respectively) and diminished its beneficial neuroprotective effects. Conclusion Preischemic dexmedetomidine administration elicited neuroprotection against global transient cerebral ischemia in rats by increasing Nrf2/HO-1 expression partly via PKC signaling, suggesting that this is the antioxidant mechanism underlying dexmedetomidine-mediated neuroprotection.

Postoperative excessive blood loss after cardiac surgery can be predicted with International Society on Thrombosis and Hemostasis scoring system / A perda sanguínea excessiva no pós-operatório de cirurgia cardíaca pode ser prevista com o sistema de classificação da Sociedade Internacional de Trombose e Hemostasia (ISTH)

Abstract Background and objective Prediction of postoperative excessive blood loss is useful for management of Intensive Care Unit after cardiac surgery. The aim of present study was to examine the effectiveness of International Society on Thrombosis and Hemostasis scoring system in patients with cardiac surgery. Method After obtaining approval from the institutional review board, the medical records of patients undergoing elective cardiac surgery using Cardio-Pulmonary Bypass between March 2010 and February 2014 were retrospectively reviewed. International Society on Thrombosis and Hemostasis score was calculated in intensive care unit and patients were divided with overt disseminated intravascular coagulation group and non-overt disseminated intravascular coagulation group. To evaluate correlation with estimated blood loss, student t-test and correlation analyses were used. Results Among 384 patients with cardiac surgery, 70 patients with overt disseminated intravascular coagulation group (n = 20) or non-overt disseminated intravascular coagulation group (n = 50) were enrolled. Mean disseminated intravascular coagulation scores at intensive care unit admission was 5.35 ± 0.59 (overt disseminated intravascular coagulation group) and 2.66 ± 1.29 (non-overt disseminated intravascular coagulation group) and overt disseminated intravascular coagulation was induced in 29% (20/70). Overt disseminated intravascular coagulation group had much more EBL for 24 h (p = 0.006) and maintained longer time of intubation time (p = 0.005). Conclusion In spite of limitation of retrospective design, management using International Society on Thrombosis and Hemostasis score in patients after cardiac surgery seems to be helpful for prediction of the post- cardio-pulmonary bypass excessive blood loss and prolonged tracheal intubation duration.

Resumo Justificativa e objetivo A previsão de perda sanguínea excessiva no pós-operatório é útil para o manejo em Unidade de Terapia Intensiva (UTI) após cirurgia cardíaca. O objetivo do presente estudo foi examinar a eficácia do sistema de classificação da Sociedade Internacional de Trombose e Hemostasia (International Society on Thrombosis and Hemostasis - ISTH) em pacientes submetidos à cirurgia cardíaca. Método Após obter a aprovação do Comitê de Pesquisa Institucional, os prontuários de pacientes submetidos à cirurgia cardíaca eletiva com circulação extracorpórea (CEC) entre março de 2010 e fevereiro de 2014 foram retrospectivamente revisados. O escore ISTH foi calculado na UTI e os pacientes foram alocados em dois grupos: grupo com coagulação intravascular disseminada (CID) manifesta e grupo com CID não manifesta. Para avaliar a correlação com a Perda Estimada de Sangue (PES), o teste t de Student e as análises de correlação foram usados. Resultados Dentre os 384 pacientes submetidos à cirurgia cardíaca, 70 com CID manifesta (n = 20) ou CID não manifesta (n = 50) foram incluídos. As médias dos escores CID na admissão na UTI foram 5,35 ± 0,59 (Grupo CID manifesta) e 2,66 ± 1,29 (Grupo CID não manifesta) e induzida CID manifesta em 29% (20/70). O grupo CID manifesta apresentou PES superior durante 24 horas (p = 0,006) e um tempo maior de intubação (p = 0,005). Conclusão Apesar da limitação do desenho retrospectivo, o uso do escore ISTH para o manejo de pacientes após cirurgia cardíaca parece ser útil para prever a perda sanguínea excessiva pós-CEC e o prolongamento da intubação traqueal.