Thoracic epidural anesthesia decreases endotoxin-induced endothelial injury

Thoracic epidural analgesia in intensive care unit patients with acute pancreatitis: the EPIPAN multicenter randomized controlled trial

BACKGROUND

Findings from preclinical studies and one pilot clinical trial suggest potential benefits of epidural analgesia in acute pancreatitis. We aimed to assess the efficacy of thoracic epidural analgesia, in addition to usual care, in improving clinical outcomes of intensive care unit patients with acute pancreatitis.

METHODS

A multicenter, open-label, randomized, controlled trial including adult patients with a clinical diagnosis of acute pancreatitis upon admission to the intensive care unit. Participants were randomly assigned (1:1) to a strategy combining thoracic epidural analgesia and usual care (intervention group) or a strategy of usual care alone (control group). The primary outcome was the number of ventilator-free days from randomization until day 30.

RESULTS

Between June 2014 and January 2019, 148 patients were enrolled, and 135 patients were included in the intention-to-treat analysis, with 65 patients randomly assigned to the intervention group and 70 to the control group. The number of ventilator-free days did not differ significantly between the intervention and control groups (median [interquartile range], 30 days [15-30] and 30 days [18-30], respectively; median absolute difference of - 0.0 days, 95% CI - 3.3 to 3.3; p = 0.59). Epidural analgesia was significantly associated with longer duration of invasive ventilation (median [interquartile range], 14 days [5-28] versus 6 days [2-13], p = 0.02).

CONCLUSIONS

In a population of intensive care unit adults with acute pancreatitis and low requirement for intubation, this first multicenter randomized trial did not show the hypothesized benefit of epidural analgesia in addition to usual care. Safety of epidural analgesia in this setting requires further investigation.

TRIAL REGISTRATION

ClinicalTrials.gov registration number NCT02126332 , April 30, 2014.

Short-lived sensitization of cardiovascular outcomes of postpartum endotoxemia in preeclamptic rats: Role of medullary solitary tract neuroinflammation

Preeclampsia (PE) is a pregnancy-related disorder with serious maternal complications. Considering the increased importance of postpartum infection in maternal morbidity and mortality, we investigated whether preeclamptic maternal programming alters cardiovascular consequences of endotoxemia in rats and the role of cardiac and brainstem neuroinflammation in this interaction. Preeclampsia was induced by oral administration of L-NAME (50 mg/kg/day) for 7 days starting from day 14 of conception. Changes in blood pressure, heart rate, and cardiac autonomic function caused by lipopolysaccharide (LPS, 5 mg/kg i.v.) were assessed in mothers at 3 weeks (weaning time) and 9 weeks postnatally. Compared with respective non-PE counterparts, LPS treatment of weaning PE mothers caused significantly greater (i) falls in blood pressure, (ii) rises in heart rate and left ventricular contractility (dP/dt_max), (iii) reductions in time and frequency domain indices of heart rate variability and shifts in cardiac sympathovagal balance (low-frequency/high-frequency ratio, LF/HF) towards parasympathetic dominance, and (iv) attenuation of reflex bradycardic responses measured by the vasoactive method. The intensified LPS effects in weaning PE rats subsided after 9 weeks of delivery. Immunohistochemical studies showed increased protein expression of nuclear factor kappa B (NF-κB) in brainstem neuronal pools of the nucleus of the solitary tract (NTS), but not rostral ventrolateral medulla (RVLM), in endotoxic PE weaning rats compared with non-PE rats. Cardiac NF-κB expression was increased by LPS but this was similarly noted in PE and non-PE rats. Together, preeclamptic maternal programming elicits short-term exacerbation of endotoxic cardiovascular and autonomic derangements due possibly to exaggerated NTS neuroinflammatory insult.

Vagal afferent activation suppresses systemic inflammation via the splanchnic anti-inflammatory pathway

Electrical stimulation of the vagus nerve (VNS) is a novel strategy used to treat inflammatory conditions. Therapeutic VNS activates both efferent and afferent fibers; however, the effects attributable to vagal afferent stimulation are unclear. Here, we tested if selective activation of afferent fibers in the abdominal vagus suppresses systemic inflammation. In urethane-anesthetized rats challenged with lipopolysaccharide (LPS, 60 µg/kg, i.v.), abdominal afferent VNS (2 Hz for 20 min) reduced plasma tumor necrosis factor alpha (TNF) levels 90 min later by 88% compared with unmanipulated animals. Pre-cutting the cervical vagi blocked this anti-inflammatory action. Interestingly, the surgical procedure to expose and prepare the abdominal vagus for afferent stimulation ('vagal manipulation') also had an anti-inflammatory action. Levels of the anti-inflammatory cytokine IL-10 were inversely related to those of TNF. Prior bilateral section of the splanchnic sympathetic nerves reversed the anti-inflammatory actions of afferent VNS and vagal manipulation. Sympathetic efferent activity in the splanchnic nerve was shown to respond reflexly to abdominal vagal afferent stimulation. These data demonstrate that experimentally activating abdominal vagal afferent fibers suppresses systemic inflammation, and that the efferent neural pathway for this action is in the splanchnic sympathetic nerves.

Sevoflurane did not show better protective effect on endothelial glycocalyx layer compared to propofol during lung resection surgery with one lung ventilation

Background

The endothelial glycocalyx layer (EGL) coats the alveolar capillary endothelium and plays important roles in pulmonary vascular protection, modulation, and hemostasis. Ischemia-reperfusion, which occurs during lung resection surgery with one lung ventilation (OLV), can damage the EGL. Sevoflurane is known for its protective effect against ischemia-reperfusion injury. Therefore, we hypothesized that lung resection surgery produces EGL damage and sevoflurane protects the EGL better than the intravenous anesthetic propofol.

Methods

Seventy-eight patients undergoing pulmonary resection were randomly allocated into the sevoflurane (n=38) and propofol (n=40) groups. All patients received OLV and protective ventilation under sevoflurane- or propofol-based anesthesia. The concentrations of EGL injury markers (heparan sulfate and human syndecan-1) and an inflammatory marker (vascular cell adhesion molecule-1) were measured from blood samples drawn at five time points (after induction, 60 min after OLV, 120 min after OLV, end of OLV, and end of surgery).

Results

OLV increased the concentrations of EGL injury markers; heparan sulfate concentrations increased from 120 minutes after OLV (120 minutes after OLV: sevoflurane, 13.3±6.8 ng/mL, P<0.05; propofol, 14.8±6.9 ng/mL, P<0.05). Human syndecan-1 concentrations also increased from 120 minutes after OLV (120 minutes after OLV: sevoflurane, 20.4±8.9 ng/mL, P<0.05; propofol, 20.5±11.8 ng/mL, P>0.05). However, no difference in EGL injury markers was observed between the sevoflurane and propofol groups at any time point. Vascular cell adhesion molecule-1 concentrations did not show any temporal changes in either group.

Conclusions

Lung resection surgery with OLV produced EGL damage without any increase in inflammation. Although shedding of heparan sulfate induced by EGL injury during lung resection surgery with OLV, was less than propofol, it was not statistically significant.

Epidural analgesia in critically ill patients with acute pancreatitis: the multicentre randomised controlled EPIPAN study protocol

BACKGROUND

Acute pancreatitis (AP) is associated with high morbidity and mortality in its most severe forms. Most patients with severe AP require intubation and invasive mechanical ventilation, frequently for more than 7 days, which is associated with the worst outcome. Recent increasing evidence from preclinical and clinical studies support the beneficial effects of epidural analgesia (EA) in AP, such as increased gut barrier function and splanchnic, pancreatic and renal perfusion, decreased liver damage and inflammatory response, and reduced mortality. Because recent studies suggest that EA might be a safe procedure in the critically ill, we sought to determine whether EA reduced AP-associated respiratory failure and other major clinical outcomes in patients with AP.

METHODS AND ANALYSIS

The Epidural Analgesia for Pancreatitis (EPIPAN) trial is an investigator-initiated, prospective, multicentre, randomised controlled two-arm trial with assessor-blinded outcome assessment. The EPIPAN trial will randomise 148 patients with AP requiring admission to an intensive care unit (ICU) to receive EA (with patient-controlled epidural administration of ropivacaine and sufentanil) combined with standard care based on current recommendations on the treatment of AP (interventional group), or standard care alone (reference group). The primary outcome is the number of ventilator-free days at day 30. Secondary outcomes include main complications of AP (eg, organ failure and mortality, among others), levels of biological markers of systemic inflammation, epithelial lung injury, renal failure, and healthcare-associated costs.

ETHICS AND DISSEMINATION

The study was approved by the appropriate ethics committee (CPP Sud-Est VI). Informed consent is required. If the combined application of EA and standard care proves superior to standard care alone in patients with AP in the ICU, the use of EA may become standard practice in experienced centres, thereby decreasing potential complications related to AP and its burden in critically ill patients. The results will be disseminated in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT02126332.

Cannabinoid 2 receptor activation reduces leukocyte adhesion and improves capillary perfusion in the iridial microvasculature during systemic inflammation

BACKGROUND

Leukocyte adhesion to the endothelium and decreased microvascular blood flow causing microcirculatory dysfunction are hallmarks of systemic inflammation. We studied the impact of cannabinoid receptor activation on the iridial microcirculation, which is accessible non-invasively in vivo, in systemic inflammation induced by endotoxin challenge.

METHODS

40 Lewis rats were used in the experiments. Endotoxemia was induced by 2 mg/kg i.v. lipopolysaccharide (LPS). Cannabinoid receptors (CBRs) were stimulated by i.v. administration of WIN 55212-2 (WIN; 1 mg/kg). CB1R antagonist (AM281; 2.5 mg/kg i.v.) or CB2R antagonist (AM630; 2.5 mg/kg i.v.) treatment prior to WIN was applied to identify the anti-inflammatory effects underlying each CBR subtype. Leukocyte-endothelial interactions were examined in rat iridial microvas culature by intravital microscopy at baseline and 1 and 2 h post-LPS. Additionally, systemic (mean arterial pressure, heart rate) and local (laser Doppler flow) hemodynamic variables were measured prior to and during cannabinoid treatments.

RESULTS

Endotoxemia resulted in severe inflammation as shown by significantly increased numbers of adherent leukocytes at 1 and 2 h observation time post-LPS challenge and decreased microcirculatory blood flow at 2 h within the iridial microcirculation. WIN treatment significantly reduced leukocyte adhesion in iridial microvessels with a diameter greater and less than 25 μm during endotoxemia (p <  0.05). Pre-treatment of animals by CB1R antagonist, AM281, did not affect WIN effects on LPS-induced leukocyte adhesion. When pre-treated with the CB2R antagonist, AM630, a reversal of the WIN-induced reduction in leukocyte adhesion was noticed in vessels with a diameter of less than 25 μm (p <  0.05). Cannabinoid treatment significantly increased the local iridial microcirculatory blood flow 2 hours after systemic LPS administration (p <  0.05).

CONCLUSIONS

Systemic administration of the CBR agonist, WIN, decreased leukocyte-adhesion and improved iridial microvascular blood flow. This effect is most likely mediated by CB2R activation. Our findings indicate that the iris microvasculature can serve as a model to study the microcirculation during systemic inflammation and help to identify potential therapies to treat microcirculatory dysfunction in diseases such as sepsis.