Intraoperative fluid balance and cardiac surgery-associated acute kidney injury: a multicenter prospective study

Abstract Background Recent data suggest the regime of fluid therapy intraoperatively in patients undergoing major surgeries may interfere in patient outcomes. The development of postoperative Acute Kidney Injury (AKI) has been associated with both Restrictive Fluid Balance (RFB) and Liberal Fluid Balance (LFB) during non-cardiac surgery. In patients undergoing cardiac surgery, this influence remains unclear. The study objective was to evaluate the relationship between intraoperative RFB vs. LFB and the incidence of Cardiac-Surgery-Associated AKI (CSA-AKI) and major postoperative outcomes in patients undergoing on-pump Coronary Artery Bypass Grafting (CABG). Methods This prospective, multicenter, observational cohort study was set at two high-complexity university hospitals in Brazil. Adult patients who required postoperative intensive care after undergoing elective on-pump CABG were allocated to two groups according to their intraoperative fluid strategy (RFB or LFB) with no intervention. Results The primary endpoint was CSA-AKI. The secondary outcomes were in-hospital mortality, cardiovascular complications, ICU Length of Stay (ICU-LOS), and Hospital LOS (H-LOS). After propensity score matching, 180 patients remained in each group. There was no difference in risk of CSA-AKI between the two groups (RR = 1.15; 95% CI, 0.85-1.56, p= 0.36). The in-hospital mortality, H-LOS and cardiovascular complications were higher in the LFB group. ICU-LOS was not significantly different between the two groups. ROCcurve analysis determined a fluid balance above 2500 mL to accurately predict in-hospital mortality. Conclusion Patients undergoing on-pump CABG with LFB when compared with patients with RFB present similar CSA-AKI rates and ICU-LOS, but higher in-hospital mortality, cardiovascular complications, and H-LOS.

Application of a pharmacokinetics-pharmacodynamics approach to the free propofol plasma levels during coronary artery bypass grafting surgery with hypothermic cardiopulmonary bypass

OBJECTIVES: The objective of this study was to apply a pharmacokinetics-pharmacodynamics approach to investigate the free propofol plasma levels in patients undergoing coronary artery bypass grafting under hypothermic conditions compared with the off-pump procedure. METHODS: Nineteen patients scheduled for on-pump coronary artery bypass grafting under hypothermic conditions (n=10) or the equivalent off-pump surgery (n=9) were anesthetized with sufentanil and propofol target-controlled infusion (2 μg/mL) during surgery. The propofol concentration was then reduced to 1 μg/mL, and a pharmacokinetics-pharmacodynamics analysis using the maximum-effect-sigmoid model obtained by plotting the bispectral index values against the free propofol plasma levels was performed. RESULTS: Significant increases (two- to five-fold) in the free propofol plasma levels were observed in the patients subjected to coronary artery bypass grafting under hypothermic conditions. The pharmacokinetics of propofol varied according to the free drug levels in the hypothermic on-pump group versus the off-pump group. After hypothermic coronary artery bypass was initiated, the distribution volume increased, and the distribution half-life was prolonged. Propofol target-controlled infusion was discontinued when orotracheal extubation was indicated, and the time to patient extubation was significantly higher in the hypothermic on-pump group than in the off-pump group (459 versus 273 min, p=0.0048). CONCLUSIONS: The orotracheal intubation time was significantly longer in the hypothermic on-pump group than in the off-pump group. Additionally, residual hypnosis was identified through the pharmacokinetics-pharmacodynamics approach based on decreases in drug plasma protein binding in the hypothermic on-pump group, which could explain the increased hypnosis observed with this drug in this group of patients.

Effects of cardiopulmonary bypass on propofol pharmacokinetics and bispectral index during coronary surgery

PURPOSE: Cardiopulmonary bypass is known to alter propofol pharmacokinetics in patients undergoing cardiac surgery. However, few studies have evaluated the impact of these alterations on postoperative pharmacodynamics. This study was designed to test the hypothesis that changes in propofol pharmacokinetics increase hypnotic effects after cardiopulmonary bypass. METHODS: Twenty patients scheduled for on-pump coronary artery bypass graft (group, n=10) or off-pump coronary artery bypass graft (group, n=10) coronary artery bypass grafts were anesthetized with sufentanil and a propofol target controlled infusion (2.0 µg/mL). Depth of hypnosis was monitored using the bispectral index. Blood samples were collected from the induction of anesthesia up to 12 hours after the end of propofol infusion, at predetermined intervals. Plasma propofol concentrations were measured using high-performance liquid chromatography, followed by a non-compartmental propofol pharmacokinetic analysis. Data were analyzed using ANOVA, considering p<0.05 as significant. RESULTS: After cardiopulmonary bypass, despite similar plasma propofol concentrations in both groups, bispectral index values were lower in the on-pump coronary artery bypass graft group. Time to extubation after the end of propofol infusion was greater in the on-pump coronary artery bypass graft group (334 ± 117 vs. 216 ± 85 min, p = 0.04). Patients undergoing cardiopulmonary bypass had shorter biological (1.82 ± 0.5 vs. 3.67 ± 1.15h, p < 0.01) and terminal elimination (6.27 ± 1.29 vs. 10.5h ± 2.18, p < 0.01) half-life values, as well as higher total plasma clearance (28.36 ± 11.40 vs.18.29 ± 7.67 mL/kg/min, p = 0.03), compared to patients in the off-pump coronary artery bypass graft group. CONCLUSION: Aside from the increased sensitivity of the brain to anesthetics after cardiopulmonary bypass, changes in propofol pharmacokinetics may contribute to its central nervous system effects.

Há espaço para o tratamento endovascular nas dissecções crônicas da aorta descendente? / Is the endovascular procedure an option for treatment of cronic type B aortic dissections?

OBJETIVO: Questões relativas a quais pacientes/doenças que efetivamente deveriam ser submetidos ao tratamento endovascular ainda geram controvérsias. O objetivo deste trabalho visa a questionar o tratamento endovascular nas dissecções crônicas tipo B de Stanford. MÉTODOS: No período de 2003 a 2006, 11 pacientes portadores de dissecção crônica da aorta tipo B de Stanford com dilatação somente no tórax (diâmetro > 5,5cm), foram submetidos à colocação de prótese endovascular autoexpansível pela artéria femoral. Todos os pacientes foram submetidos à angiotomografia de controle com 6 meses, 1 ano e após, anualmente, com o intuito de avaliar a presença de fluxo na falsa luz e estudar a evolução dos diâmetros da aorta torácica descendente e abdominal no decorrer do tempo. Para esta análise foram utilizados os testes Anova de duas vias para medidas repetidas e o qui-quadrado com o programa SPSS 13. RESULTADOS: Não houve mortalidade hospitalar. Nenhum paciente apresentou endoleak imediatamente após a operação. Durante o período de seguimento médio de 28 meses/paciente, não houve óbitos, um paciente foi submetido à substituição da aorta tóraco-abdominal e dois aguardam esta mesma intervenção. A endoprótese interrompeu o fluxo na falsa luz no tórax em 72,7 por cento dos pacientes e, no abdome, somente em 18,2 por cento, porém isto não implicou na redução dos diâmetros da aorta torácica nem abdominal. CONCLUSÃO: O tratamento endovascular nas dissecções crônicas tipo B de Stanford parece não ser suficiente para tratar esses pacientes no curto/médio prazo, apesar do tamanho reduzido da amostra estudada.

OBJECTIVE: Questions regarding the specific patient/disease that should be submitted to the endovascular procedure still remain unclear. The purpose of this report is to evaluate the endovascular treatment in chronic type B aortic dissections. METHODS: Between 2003 and 2006, 11 patients with chronic type B aortic dissection were submitted to endovascular procedure through femoral artery. All of them were monitored with CT within 6 months, 1 year and afterwars anually. We prospectively evaluated false lumen patency and thoracic and abdominal aortic diameters in each time point. The data comparisons were made using Anova and chi-square tests with SPSS 13. RESULTS: The endovascular stent-graft deployment was technically successful for all patients, with no hospital mortality. During the follow-up period the false lumen flows remained persistent in the thorax in 27.3 percent of the patients and in the abdomen in 81.8 percent. However, in all patients, in both segments, the aorta diameter was not significantly changed in size and shape. CONCLUSION: Despite the small number of studied patients, the endovascular procedure for chronic type B aortic dissections does not appear to be an option for the treatment of these patients.