Laurent Dupic

Postresuscitation syndrome: Potential role of hydroxyl radical-induced endothelial cell damage

Objective:After out of hospital cardiac arrest, it has been reported that endothelium dysfunction may occur during the postresuscitation syndrome. However, the consequences of the reperfusion phase on endothelial reactive oxygen species production and redox homeostasis have not been explored in out of hospital cardiac arrest patients. Design:Prospective, observational study. Setting:Medical intensive care unit in a university hospital. Patients:Twenty successfully resuscitated out of hospital cardiac arrest patients, seven septic shock patients, and ten healthy volunteers. Intervention:Plasma was collected from patients at admission and 12, 24, 36, 48, and 72 hrs after cardiac arrest. We studied the production of reactive oxygen species and cell survival during plasma perfusion using perfused endothelial cells (human umbilical vein endothelial cells) as a model. Cell antioxidant response was studied by measuring superoxide dismutase, glutathione peroxidase, and glutathione reductase activities and reduced and oxidized glutathione levels. Mitochondrial respiratory chain activity was assessed by measuring complex I, II, III, and IV activities and anaerobic glycolysis by measuring glucose-6-phosphate dehydrogenase activity. Measurements and Main Results:Using perfused endothelial cells as a model, we demonstrate that plasma from out of hospital cardiac arrest patients induced on naive human umbilical vein endothelial cells a significant and massive cell death compared to plasma from septic shock patients and healthy volunteers. An increase of reactive oxygen species production with a decrease in antioxidant defenses (superoxide dismutase, glutathione peroxidase, and glutathione reductase activities, reduced and oxidized glutathione levels) was observed. The metabolic consequence of plasma exposure showed that mitochondrial respiratory chain activity was significantly impaired and anaerobic glycolysis was significantly increased. Inhibiting hydroxyl radical production significantly decreased cell death, suggesting that plasma from out of hospital cardiac arrest induced significant cell death by triggering the Fenton reaction. Conclusion:Plasma from out of hospital cardiac arrest induces major endothelial toxicity with an acute pro-oxidant state in the cells and impairment of mitochondrial respiratory chain activity. This toxicity could be due to hydroxyl radical production by activation of the Fenton reaction.

Weaning children from mechanical ventilation with a computer-driven system (closed-loop protocol): a pilot study.

Objective: To evaluate the applicability, tolerance, and efficacy of a closed-loop protocol to wean children from mechanical ventilation. Design: Prospective single-center pilot study. Setting: Tertiary care university hospital. Patients: Twenty mechanically ventilated children aged between 1 and 17 yrs, with a body weight ≥10 kg, no inotropes, and no heavy sedation. Interventions: Patients were weaned in pressure support mode by a closed-loop computerized protocol (closed-loop protocol) that interprets clinical data in real time and controls pressure support levels. Measurements and Main Results: The closed-loop protocol applicability and tolerance were evaluated. The efficacy of this protocol was evaluated by comparing the duration of mechanical ventilation with a historical group of 20 patients weaned with a clinician-decision protocol. The closed-loop protocol successfully decreased pressure support ventilation in 16 children, recommended separation from the ventilator in 14 children, and did not cause any serious adverse events. Mechanical ventilation duration was 5.1 ± 4.2 days in the closed-loop group and 6.7 ± 11.5 days (mean ± sd) in the clinician-decision group (p = .33) with no difference in the need for reintubation or noninvasive mechanical ventilation (one of 20 and four of 20, respectively; p = .20). Conclusions: A closed-loop protocol was successfully used to wean children from mechanical ventilation. Further studies are required to assess the impact of this novel therapeutic strategy on the length of mechanical ventilation.

Targeting the microcirculation in resuscitation of acutely unwell patients.

Purpose of reviewThe ultimate goals of hemodynamic therapy in acutely unwell patients are to restore effective tissue perfusion and oxygen delivery to maintain cellular metabolism. Optimization of systemic hemodynamics may improve the time course of microcirculatory dysfunction and eventually the patients outcome. However, relationships between systemic hemodynamics and microcirculatory changes during resuscitation are complex and underperfused microcirculation may persist, despite restored macrohemodynamics. Thus, targeting the microcirculation is a logical goal to obtain an adequate resuscitation. Recent findingsThe impact of systemic interventions such as fluid resuscitation, vasopressor therapy, and transfusion has been evaluated on microcirculatory perfusion in septic-shock patients. It demonstrated inconstant improvement according to time-course evolution of the underlying pathology with interindividual variability. Thus, therapy targeting the microcirculation should be adapted to individual microcirculatory monitoring. Specific therapy with nitroglycerin did not promote microcirculation in septic shock but was associated with microcirculatory improvement in cardiogenic shock. SummaryMicrocirculatory hemodynamics have to be restored as soon as possible during the early phase of the management of acutely unwell patients. Future trials should test whether microcirculation-guided strategy could better improve organ dysfunction than global hemodynamic-guided strategy. An optimal resuscitation has to restore the systematic hemodynamics and make sure of the quality of the microcirculation.

Intestinal transplantation for total intestinal aganglionosis: a series of 12 consecutive children

BACKGROUND Management of patients with total intestinal aganglionosis (TIA) is a medical challenge because of their dependency on parenteral nutrition (PN). Intestinal transplantation (ITx) represents the only alternative treatment for patients with irreversible intestinal failure for achieving intestinal autonomy. METHODS Among 66 patients who underwent ITx in our center, 12 had TIA. They received either isolated ITx (n = 4) or liver-ITx (LITx, n = 8) after 10 to 144 months of total PN. All grafts included the right colon. RESULTS After a median follow-up of 57 months, the survival rate was 62.5% in the LITx group and 100% in the ITx patients. The graft survival rate was 62.5% in the LITx group and 75% in the ITx group. All the surviving patients were fully weaned from total PN, after a median of 57 days. Pull through of the colon allograft was carried out in all patients. Fecal continence is normal in all but one of the surviving children. CONCLUSION These results suggest that ITx with colon grafting should be the preferred therapeutic option in TIA. Early referral to a transplantation center after diagnosis of TIA is critical to prevent PN-related cirrhosis and thereby to permit ITx, which is associated with a good survival rate.

Pivotal role of glutathione depletion in plasma-induced endothelial oxidative stress during sepsis.

Objective:Plasma from septic shock patients can induce production of reactive oxygen species (ROS) by human umbilical vein endothelial cells (HUVEC) in vitro. How endothelial cells defend themselves against ROS under increased oxidative stress has not yet been examined. This study investigates the antioxidant defenses of HUVEC exposed to plasma obtained from either septic shock patients or healthy volunteers. Design:Prospective, observational study. Setting:Medical intensive care unit in a university hospital. Patients:Twenty-five patients with septic shock and 10 healthy volunteers. Interventions:Blood samples were collected within the first 24 hrs of septic shock. In vitro HUVEC production of ROS was studied by spectrofluorimetry using 2′,7′-dichlorodihydrofluorescein diacetate fluorescent dye. Reactive nitrogen species were also assessed. Intracellular reduced glutathione (GSH) levels were measured using monochlorobimane fluorescent dye. Activity of catalase and superoxide dismutase in HUVEC were also measured. Cell death was assessed using YOPRO fluorescent dye and the MTT assay. Measurements and Results:On admission, the septic shock populations mean age was 55 yrs old, the mean Sequential Organ Failure Assessment score was 12, mean simplified acute physiology score was 50, and intensive care unit mortality rate was 45%. Evaluation of HUVEC antioxidant defenses showed a significantly decreased GSH level, increased catalase activity, and unchanged superoxide dismutase activity. ROS levels and cell death were significantly reduced when cells were pretreated with N-acetylcysteine or GSH, but no changes in reactive nitrogen species were observed. Conclusion:This study demonstrates that plasma-induced ROS production by HUVEC is associated with an intracellular decrease in reduced GSH. Both ROS levels and cell death decreased when N-acetylcysteine or GSH were added before exposing the cells to plasma. These data suggest a pivotal role of alterations in GSH in damage caused by sepsis-generated ROS in endothelial cell.

Long-term outcomes in Ornithine Transcarbamylase deficiency: a series of 90 patients

BackgroundThe principal aim of this study was to investigate the long-term outcomes of a large cohort of patients with ornithine transcarbamylase deficiency (OTCD) who were followed up at a single medical center.MethodsWe analyzed clinical, biochemical and genetic parameters of 90 patients (84 families, 48 males and 42 females) with OTCD between 1971 and 2011.ResultsTwenty-seven patients (22 boys, 5 girls) had a neonatal presentation; 52 patients had an “intermediate” late-onset form of the disease (21 boys, 31 girls) that was revealed between 1 month and 16 years; and 11 patients (5 boys, 6 girls) presented in adulthood (16 to 55 years). Patients with a neonatal presentation had increased mortality (90% versus 13% in late-onset forms) and peak plasma ammonium (mean value: 960 μmol/L versus 500 μmol/L) and glutamine (mean value: 4110 μmol/L versus 1000 μmol/L) levels at diagnosis. All of the neonatal forms displayed a greater number of acute decompensations (mean value: 6.2/patient versus 2.5 and 1.4 in infants and adults, respectively). In the adult group, some patients even recently died at the time of presentation during their first episode of coma. Molecular analyses identified a deleterious mutation in 59/68 patients investigated. Single base substitutions were detected more frequently than deletions (69% and 12%, respectively), with a recurrent mutation identified in the late-onset groups (pArg40 His; 13% in infants, 57% in adults); inherited mutations represented half of the cases. The neurological score did not differ significantly between the patients who were alive in the neonatal or late-onset groups and did not correlate with the peak ammonia and plasma glutamine concentrations at diagnosis. However, in late-onset forms of the disease, ammonia levels adjusted according to the glutamine/citrulline ratio at diagnosis were borderline predictors of low IQ (p = 0.12 by logistic regression; area under the receiver operating characteristic curve of 76%, p <0.05).ConclusionsOTCD remains a severe disease, even in adult-onset patients for whom the prevention of metabolic decompensations is crucial. The combination of biochemical markers warrants further investigations to provide additional prognostic information regarding the neurological outcomes of patients with OTCD.

Norepinephrine Decreases Fluid Requirements and Blood Loss While Preserving Intestinal Villi Microcirculation during Fluid Resuscitation of Uncontrolled Hemorrhagic Shock in Mice

Background: Norepinephrine administration is controversial during hemorrhagic shock resuscitation to stabilize mean arterial pressure (MAP) level because it could have deleterious effects on local circulations. The authors investigated the effect of norepinephrine on intestinal microcirculation during fluid resuscitation in uncontrolled hemorrhagic shock. Methods: Mice (n = 6 per group) submitted to an uncontrolled hemorrhagic shock by tail section were randomly assigned to a resuscitation with fluid but without norepinephrine to target a MAP level of 50 mmHg (FR50) or 60 mmHg (FR60) or a resuscitation with fluid and norepinephrine to target a MAP level of 50 mmHg (FRNE50) or 60 mmHg (FRNE60). Intestinal microcirculation was observed by intravital microscopy. Results: Fluid requirements were lower in groups resuscitated with fluid and norepinephrine than in groups resuscitated with fluid without norepinephrine (74.6 ± 45.1 in FR50 vs. 28.1 ± 10.0 µl/g in FRNE50; P = 0.004 and 161.9 ± 90.4 in FR60 vs. 44.5 ± 24.0 µl/g in FRNE60; P = 0.041). Blood loss was not statistically different between FR50 and FRNE50 (14.8 ± 8.3 vs. 8.5 ± 2.9 µl/g; P = 0.180) but was significantly lower in FRNE60 than in FR60 (10.1 ± 4.2 vs. 22.6 ± 9.6 µl/g; P = 0.015). This beneficial effect was associated with the restoration of intestinal microcirculation to the same extent in fluid resuscitated groups without norepinephrine (FR50 and FR60) and fluid resuscitated groups with norepinephrine (FRNE50 and FRNE60). Conclusions: During MAP-directed resuscitation of uncontrolled hemorrhagic shock, the administration of norepinephrine decreased blood loss and fluid requirements while preserving intestinal villi microcirculation.