Isoflurane Anesthesia Initiated at the Onset of Reperfusion Attenuates Oxidative and Hypoxic-Ischemic Brain Injury

This study demonstrates that in mice subjected to hypoxia-ischemia (HI) brain injury isoflurane anesthesia initiated upon reperfusion limits a release of mitochondrial oxidative radicals by inhibiting a recovery of complex-I dependent mitochondrial respiration. This significantly attenuates an oxidative stress and reduces the extent of HI brain injury. Neonatal mice were subjected to HI, and at the initiation of reperfusion were exposed to isoflurane with or without mechanical ventilation. At the end of HI and isoflurane exposure cerebral mitochondrial respiration, H₂O₂ emission rates were measured followed by an assessment of cerebral oxidative damage and infarct volumes. At 8 weeks after HI navigational memory and brain atrophy were assessed. In vitro, direct effect of isoflurane on mitochondrial H₂O₂ emission was compared to that of complex-I inhibitor, rotenone. Compared to controls, 15 minutes of isoflurane anesthesia inhibited recovery of the compex I-dependent mitochondrial respiration and decreased H₂O₂ production in mitochondria supported with succinate. This was associated with reduced oxidative brain injury, superior navigational memory and decreased cerebral atrophy compared to the vehicle-treated HI-mice. Extended isoflurane anesthesia was associated with sluggish recovery of cerebral blood flow (CBF) and the neuroprotection was lost. However, when isoflurane anesthesia was supported with mechanical ventilation the CBF recovery improved, the event associated with further reduction of infarct volume compared to HI-mice exposed to isoflurane without respiratory support. Thus, in neonatal mice brief isoflurane anesthesia initiated at the onset of reperfusion limits mitochondrial release of oxidative radicals and attenuates an oxidative stress. This novel mechanism contributes to neuroprotective action of isoflurane. The use of mechanical ventilation during isoflurane anesthesia counterbalances negative effect of isoflurane anesthesia on recovery of cerebral circulation which potentiates protection against reperfusion injury

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Long-term neurological outcome of the HI-brain injury after isoflurane exposure.

<p>(A)—Navigational memory: time spent in the “platform quadrant” by naïve mice (n = 21) and HI-mice re-oxygenated without (HI, n = 14), or with isoflurane (HI+Iso, n = 14). Representative tracings of swimming path during probe trial in the same groups of mice. (B)—Extent of brain atrophy in the ipsilateral hemisphere and representative Nissl-stained brain images from adult mice treated with isoflurane for initial 15 minutes of reperfusion (HI+Iso, n = 13) or RA (HI, n = 14).</p

In-vitro and ex-vivo effect of isoflurane on mitochondrial ROS release.

<p>(A)—Mitochondrial H₂O₂ emission rate and representative H₂O₂ fluorescence tracings in HI-mice at the end of HI (n = 6) and at 15 minutes of reperfusion with (n = 6) or without (n = 6) isoflurane anesthesia. (B and C)—H₂O₂ emission rates with representative H₂O₂ fluorescence tracings from mitochondria fueled with succinate (B) or malate-glutamate (C) and exposed to hyperoxic buffer (O₂) in the presence of vehicle (O₂ + Veh, n = 4 and 6), or Isoflurane (O₂ + Iso, n = 4 and 6), or Rotenone (O₂ + Rot, n = 4 and 6) and compared to controls (Normox, n = 4 and 6). P-values and study groups are indicated. * p < 0.01 compared to normoxia.</p

Mechanical ventilation enhances neuroprotection of isoflurane.

<p>(A)—CBF during HI and reperfusion in mice re-oxygenated with RA (n = 4) or Isoflurane for initial 15 minutes (Iso—RA, n = 4), or 30 minutes (Iso, n = 4), or mice re-oxygenated with isoflurane combined with mechanical ventilation (Iso+Vent, n = 4). * p < 0.02 between groups, Dashed square indicates analyzed area. (B)—Infarct volume in mice re-oxygenated under isoflurane anesthesia for 15 or 30 minutes with (n = 22) or without (n = 35) mechanical ventilation. * p = 0.017 compared to the mice ventilated for 30 minutes.</p

Blood gases during isoflurane anesthesia with or without MV.

<p>* p < 0.002 compared to Iso. MV group. Data are Mean ± SEM</p><p>Blood gases during isoflurane anesthesia with or without MV.</p

Post-HI isoflurane anesthesia attenuates oxidative brain damage and extent of brain injury.

<p>(A and B)—Mitochondrial aconitase activity and expression of 3-Nitrotyrosine in brains obtained from naïve mice (n = 11 and 7) and in HI-mice reperfused for initial 15 minutes with isoflurane (n = 12 and 9) or RA (n = 10 and 6). (C)—representative 3-Nitrotyrosine western blot. (D)—Infarct volume and representative TTC-stained cerebral images of HI-mice reperfused without (RA, n = 50), or with isoflurane anesthesia: for initial 15 min (n = 35), or initial 30 min (n = 35), or delayed (30–45 minutes, n = 16).</p

Experimental design.

<p><b>Mitochondrial phosphorylating respiration rates after HI</b>. (A)—HI-mice, upon reperfusion, were exposed to either room air or isoflurane with or without mechanical ventilation (MV) for different time of reperfusion. (B)—Changes in SaO₂ in naive mice (n = 6), and mice exposed to 2 Vol% isoflurane with (n = 6) or without (n = 4) 30% oxygen supplementation, * p < 0.01. (C)—Mitochondrial phosphorylating and uncoupled respiration rates in naïve mice (n = 10), HI-mice at the end of HI-insult (n = 5), and at 15 minutes of reperfusion under isoflurane (HI+Iso, n = 14) or without (HI+RA, n = 14) isoflurane anesthesia. (D)—Representative cerebral mitochondrial respiration tracings from HI-mice tested at the end of HI (End of HI) and 15 minutes of reperfusion with isoflurane exposure (15’ Rep+Iso) or room air (15’ Rep+RA).</p