Predictors of transfusion outcomes in pediatric complex cranial vault reconstruction: a multicentre observational study from the Pediatric Craniofacial Collaborative Group.

PURPOSE: Pediatric patients undergoing complex cranial vault reconstruction (CCVR) are at risk of significant perioperative blood loss requiring blood product transfusion. Minimizing allogeneic blood product transfusion is an important goal because of the associated risks and cost. The impact of patient and surgical variables on transfusion is unknown in this population. Our primary aim was to examine relationships between demographic and perioperative variables and blood product transfusion outcomes in CCVR. METHODS: The multicentre Pediatric Surgery Perioperative Registry was checked for children undergoing CCVR between June 2012 and September 2016. Univariable and multivariable analyses were performed examining patient, procedure, and blood conservation variables and their relationship to three outcomes: intraoperative red blood cell-containing product (RBC-CP) transfusion, total perioperative blood donor exposures, and transfusion-free hospitalization. RESULTS: The registry search returned data from 1,814 cases. Age and surgical duration were the only variables significantly associated with all three outcomes studied. Predictors of reduced RBC-CP transfusion included lower American Society of Anesthesiologists (ASA) physical status and antifibrinolytic administration. Total cranial vault reconstruction, intraoperative vasoactive infusion, and presence of a tracheostomy predicted increased donor exposures. Increased body weight, higher preoperative hematocrit, and utilization of intraoperative cell saver and transfusion protocols were associated with transfusion-free hospitalization. CONCLUSION: Clinical factors associated with increased allogeneic blood product transfusion in pediatric CCVR include: age ≤ 24 months, ASA status ≥ III, preoperative anemia, prolonged surgical duration, lack of intraoperative antifibrinolytic use, lack of intraoperative cell saver use, and the lack of transfusion protocols.

RéSUMé: OBJECTIF: Les patients pédiatriques subissant une reconstruction complexe de la voûte crânienne courent un risque de pertes sanguines périopératoires importantes nécessitant la transfusion de produits sanguins. La minimisation de la transfusion de produits sanguins allogènes constitue un objectif majeur étant donné les risques et les coûts associés. L'impact des variables liées au patient et à la chirurgie sur la transfusion est inconnu dans cette population. Notre objectif principal était d'examiner les liens entre les variables démographiques et périopératoires, et les résultats des transfusions sanguines suite à une reconstruction complexe de la voûte crânienne. MéTHODE: Le Registre périopératoire multicentrique de chirurgie pédiatrique (Pediatric Surgery Perioperative Registry) a été consulté afin d'en extraire les dossiers de tous les enfants ayant subi une reconstruction complexe de la voûte crânienne entre juin 2012 et septembre 2016. Des analyses univariées et multivariées ont été réalisées et ont examiné les variables concernant les patients, l'intervention et la conservation du sang ainsi que les relations entre ces données et trois critères : la transfusion peropératoire de produits contenant des érythrocytes, l'exposition durant toute la période périopératoire aux dons de sang, et l'hospitalisation sans transfusion. RéSULTATS: L'examen du Registre a permis d'extraire les données de 1814 cas. L'âge et la durée de la chirurgie étaient les deux seules variables à afficher une association significative aux trois critères à l'étude. Les prédicteurs d'une transfusion réduite d'érythrocytes étaient un statut physique ASA (American Society of Anesthesiologists) plus bas et l'administration d'agents antifibrinolytiques. La reconstruction totale de la voûte crânienne, la perfusion peropératoire d'agents vasoactifs et la présence d'une trachéostomie constituaient des prédicteurs d'exposition plus importante aux dons de sang. Un poids corporel accru, un hématocrite préopératoire plus élevé et l'utilisation de systèmes d'autotransfusion peropératoire et de protocoles de transfusion étaient associés à une hospitalisation sans transfusion. CONCLUSION: Les facteurs cliniques associés à une augmentation des transfusions de produits sanguins allogènes dans les cas de reconstruction complexe de la voûte crânienne chez l'enfant sont : un âge ≤ 24 mois, un statut ASA ≥ III, une anémie préopératoire, la durée prolongée de la chirurgie, l'absence d'utilisation peropératoire d'antifibrinolytiques, l'absence d'utilisation de systèmes d'autotransfusion peropératoire, et l'absence de protocoles de transfusion.

Double-Blind, Randomized, Placebo-Controlled Trial Comparing the Effects of Antithrombin Versus Placebo on the Coagulation System in Infants with Low Antithrombin Undergoing Congenital Cardiac Surgery.

OBJECTIVES: To determine whether precardiopulmonary bypass (CPB) normalization of antithrombin levels in infants to 100% improves heparin sensitivity and anticoagulation during CPB and has beneficial effects into the postoperative period. DESIGN: Randomized, double-blinded, placebo-controlled prospective study. SETTING: Multicenter study performed in 2 academic hospitals. PARTICIPANTS: The study comprised 40 infants younger than 7 months with preoperative antithrombin levels <70% undergoing CPB surgery. INTERVENTIONS: Antithrombin levels were increased with exogenous antithrombin to 100% functional level intraoperatively before surgical incision. MEASUREMENTS AND MAIN RESULTS: Demographics, clinical variables, and blood samples were collected up to postoperative day 4. Higher first post-heparin activated clotting times (sec) were observed in the antithrombin group despite similar initial heparin dosing. There was an increase in heparin sensitivity in the antithrombin group. There was significantly lower 24-hour chest tube output (mL/kg) in the antithrombin group and lower overall blood product unit exposures in the antithrombin group as a whole. Functional antithrombin levels (%) were significantly higher in the treatment group versus placebo group until postoperative day 2. D-dimer was significantly lower in the antithrombin group than in the placebo group on postoperative day 4. CONCLUSION: Supplementation of antithrombin in infants with low antithrombin levels improves heparin sensitivity and anticoagulation during CPB without increased rates of bleeding or adverse events. Beneficial effects may be seen into the postoperative period, reflected by significantly less postoperative bleeding and exposure to blood products and reduced generation of D-dimers.

Reduction in blood transfusion in a cohort of infants having cardiac surgery with cardiopulmonary bypass after instituting a goal-directed transfusion policy.

BACKGROUND: Current trends in pediatric cardiac surgery and anesthesiology include goal-directed allogeneic blood transfusion, but few studies address the transfusion of platelets and cryoprecipitate. We report a quality improvement initiative to reduce the transfusion of platelets and cryoprecipitate in infants having cardiac surgery with cardiopulmonary bypass (CPB). METHODS: Data from 50 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB were prospectively collected after the institution of a policy to obtain each patient's platelet and fibrinogen levels during the rewarming phase of CPB. Data from 48 consecutive patients weighing four to ten kilograms having cardiac surgery with CPB prior to the implementation of the policy change were retrospectively collected. Demographics, laboratory values and blood product transfusion data were compared between the groups, using the Chi-square/Fisher's exact test or the T-Test/Wilcoxon Rank-Sum test, as appropriate. RESULTS: The results showed more total blood product exposures in the control group during the time from bypass through the first twenty-four post-operative hours (median of 2 units versus 1 unit in study group, p=0.012). During the time period from CPB separation through the first post-operative day, 67% of patients in the control group received cryoprecipitate compared to 32% in the study group (p=0.0006). There was no difference in platelet exposures between the groups. CONCLUSION: Checking laboratory results during the rewarming phase of CPB reduced cryoprecipitate transfusion by 50%. This reproducible strategy avoids empiric and potentially unnecessary transfusion in this vulnerable population.

Aprotinin improves functional outcome but not cerebral infarct size in an experimental model of stroke during cardiopulmonary bypass.

BACKGROUND: Aprotinin, a nonspecific serine protease inhibitor, has been used to decrease bleeding and reduce the systemic inflammatory response after cardiopulmonary bypass (CPB). Studies have variably linked aprotinin administration with both improved as well as adverse cerebral consequences after cardiac surgery. We designed this study to determine whether an antiinflammatory dose of aprotinin could improve the histologic and functional neurologic outcome in a rat model of focal cerebral ischemia during CPB. METHODS: After surgical preparation, the animals were randomized into 2 groups: an aprotinin group (60,000 kIU/kg IV) and a control group (0.9% NaCl IV). Normothermic CPB was performed for 60 minutes during which time a partial overlapping 60 minutes of right middle cerebral artery occlusion was induced. Cytokines (tumor necrosis factor-alpha, interleukin [IL]-1beta, IL-6, and IL-10) were measured at baseline, the end of CPB, then 2 and 24 hours after CPB. On postoperative day 3, the animals underwent functional neurologic testing and histologic assessment of cerebral infarct volume. RESULTS: There was a reduction in systemic inflammation in the aprotinin group compared with the control group, demonstrated by lower levels of IL-1beta (P = 0.035) and IL-6 (P = 0.047). The aprotinin group also had a better functional neurologic performance (median [interquartile range]: aprotinin 27 [8] vs control 32 [6]; P = 0.042). However, there was no difference in cerebral infarct volume (aprotinin 306 [27] mm(3) vs control 297 [52] mm(3); P = 0.599). CONCLUSIONS: In this experimental model of stroke occurring during CPB, aprotinin decreased the systemic inflammatory response to CPB. Although there was no difference in the cerebral infarct volume, there was a small improvement in the short-term functional neurologic outcome in the aprotinin group.

Exacerbation of systemic inflammation and increased cerebral infarct volume with cardiopulmonary bypass after focal cerebral ischemia in the rat.

OBJECTIVE: Stroke remains a significant contributor to morbidity and mortality after cardiac surgery. Cardiopulmonary bypass is known to induce a significant inflammatory response, which could adversely influence outcomes. We hypothesized that cardiopulmonary bypass, through an enhanced systemic inflammatory response, might affect outcomes after focal cerebral ischemia. METHODS: Wistar rats (275-300 g) were anesthetized, surgically prepared for cardiopulmonary bypass and right middle cerebral artery occlusion, and randomly allocated to 2 groups: focal cerebral ischemia alone (n = 9) and focal cerebral ischemia combined with normothermic cardiopulmonary bypass (n = 8). Serum cytokines (tumor necrosis factor alpha and interleukins 1beta, 6, and 10) were measured at baseline, at end of bypass, and at 2, 6, and 24 hours after bypass. On postoperative day 3, animals underwent neurologic testing, after which the brains were prepared for assessment of cerebral infarct volume. Data were compared between groups by Mann-Whitney U test. RESULTS: Compared with the ischemia-alone group, the ischemia plus bypass group had significantly higher levels of circulating tumor necrosis factor alpha and interleukins 1beta and 10 at the end of bypass and 2 hours after bypass. In addition, the ischemia plus bypass animals had larger total cerebral infarct volumes (286 +/- 125 mm(3)) than did those with ischemia alone (144 +/- 85 mm(3), P = .0124). CONCLUSIONS: Cardiopulmonary bypass increased cerebral infarct size after focal cerebral ischemia in rats. This worsening of outcome may in part be related to an augmented inflammatory response that accompanies cardiopulmonary bypass.

Longitudinal assessment of neurocognitive function in rats after cardiopulmonary bypass: evidence for long-term deficits.

OBJECTIVE(S): Neurologic and neurocognitive dysfunction after cardiopulmonary bypass (CPB) have been shown in both clinical and experimental settings. Although short-term outcome has been evaluated in rats, the assessment of neurocognitive dysfunction with long-term follow-up has not been reported in experimental CPB models. The objective of this study was to evaluate the effects of CPB on long-term neurocognitive function in the rat. DESIGN: Prospective, interventional study. SETTING: A university research laboratory. PARTICIPANTS: Male Sprague-Dawley rats. INTERVENTIONS: Sprague-Dawley rats were randomized to either CPB (n = 19) or sham-operated groups (n = 17). On days 3, 7, and 14 and at 6 weeks after surgery, the rats were submitted to standardized neurologic testing (Neuroscore). In addition, the animals underwent cognitive testing in the Morris water maze (MWM), including basic, probe, and reversal trial protocols during the first 19 postoperative days (short-term cognitive outcome) and then repeated 6 weeks after surgery (long-term cognitive outcome). MEASUREMENTS AND MAIN RESULTS: The CPB group had worse Neuroscores (day 3, 5[2]; day 7, 7[2]; day 14, 5[1]; 6 weeks, 5[1]) compared with the sham group (day 3, 7[2]; day 7, 7[1]; day 14, 7[1]; 6 weeks, 7[1]) at all time points tested (p < 0.05). In the MWM, the CPB group showed both short-term and persistent long-term neurocognitive dysfunction. CONCLUSIONS: Compared with sham-operated controls, rats undergoing CPB showed worse neurologic and neurocognitive outcome early after surgery. Importantly, long-term deficits also persisted at 6 weeks after surgery.

Cerebral ischemia/stroke and small ubiquitin-like modifier (SUMO) conjugation--a new target for therapeutic intervention?

Transient cerebral ischemia/stroke activates various post-translational protein modifications such as phosphorylation and ubiquitin conjugation that are believed to play a major role in the pathological process triggered by an interruption of blood supply and culminating in cell death. A new system of post-translational protein modification has been identified, termed as small ubiquitin-like modifier (SUMO) conjugation. Like ubiquitin, SUMO is conjugated to the lysine residue of target proteins in a complex process. This review summarizes observations from recent experiments focusing on the effect of cerebral ischemia on SUMO conjugation. Transient global and focal cerebral ischemia both induced a rapid, dramatic and long-lasting rise in levels of SUMO2/3 conjugation. After transient focal cerebral ischemia, SUMO conjugation was particularly prominent in neurons located at the border of the ischemic territory where SUMO-conjugated proteins translocated to the nucleus. Many SUMO conjugation target proteins are transcription factors and sumoylation has been shown to have a major impact on the activity, stability, and cellular localization of target proteins. The rise in levels of SUMO-conjugated proteins is therefore likely to have a major effect on the fate of post-ischemic neurons. The sumoylation process could provide an exciting new target for therapeutic intervention.

Xenon and the inflammatory response to cardiopulmonary bypass in the rat.

OBJECTIVE: The purpose of this study was to investigate the effect of xenon on the inflammatory response to cardiopulmonary bypass. DESIGN: Prospective, randomized experimental study. SETTING: University research laboratory. PARTICIPANTS: Sprague-Dawley rats. INTERVENTIONS: After surgical preparation, rats were randomly divided into 4 groups: (1) SHAM rats were cannulated but did not undergo cardiopulmonary bypass; (2) cardiopulmonary bypass rats were subjected to 60 minutes of cardiopulmonary bypass using an oxygenator receiving a 30% O(2), 65% N(2), and 5% CO(2) gas mixture; (3) MK801 rats received MK801 (0.15 mg/kg intravenous) 15 minutes before 60 minutes of cardiopulmonary bypass with the same gas mixture; and (4) xenon rats underwent 60 minutes of cardiopulmonary bypass receiving a 30% O(2), 60% xenon, 5% N(2), and 5% CO(2) gas mixture. MEASUREMENTS AND MAIN RESULTS: All bypass groups showed elevations in both cytokines compared with the SHAM-operated group. However, the inflammatory response to cardiopulmonary bypass in the group receiving xenon was no different from the other bypass groups. CONCLUSIONS: Xenon appears to have no effect on the inflammatory response to cardiopulmonary bypass, making its previously described neuroprotective effect during cardiopulmonary bypass likely independent of any inflammation modulation.

Cognitive dysfunction after cardiac surgery: revisiting etiology.

Cognitive dysfunction remains a frequent complication of cardiac surgery. Despite many years of research, few preventive strategies and no definitive therapeutic options exist for the management of this troublesome clinical problem. This shortcoming may be secondary to an incomplete understanding of the pathophysiology and etiology of cognitive loss after cardiac surgery; a better understanding of the etiology is essential to finding new therapies. The etiology of cognitive dysfunction after cardiac surgery is multifactorial and includes cerebral microembolization, global cerebral hypoperfusion, systemic and cerebral inflammation, cerebral temperature perturbations, cerebral edema, and possible blood-brain barrier dysfunction, all superimposed on genetic differences in patients that may make them more susceptible to injury or unable to repair from injury once it has occurred. This review expands on these potential etiologies in detailing the evidence for their existence.

Cardiopulmonary bypass reduces the minimum alveolar concentration for isoflurane.

OBJECTIVE: The purpose of this investigation was to determine the influence of cardiopulmonary bypass (CPB) on the minimum alveolar concentration (MAC) of isoflurane in a rat model of CPB. DESIGN: Prospective. SETTING: University research laboratory. PARTICIPANTS: Sprague-Dawley rats. INTERVENTIONS: Using tail-clamp methodology, the pre- and post-CPB MAC for isoflurane was studied. METHODS AND MAIN RESULTS: Rats were anesthetized with isoflurane, intubated, ventilated, and surgically prepared for CPB, after which they were randomized to either Sham-operated or CPB groups. The CPB group (n = 10) underwent 90 minutes of normothermic nonpulsatile CPB. The Sham group (n = 13) were cannulated but did not undergo CPB. Pre- and post-CPB MAC determinations were compared within groups using a paired Student t test. The CPB group had a pre-CPB baseline isoflurane MAC of 1.09% +/- 0.11% versus 1.09% +/- 0.08% in the Sham group (p = 0.90). Twenty minutes after CPB, the CPB group exhibited a decrease in MAC to 0.98% +/- 0.14% (p = 0.0026, compared with baseline). The MAC in the Sham group was unchanged (p = 0.5852, compared with baseline). Two hours after CPB, the MAC in the CPB group remained lower compared with baseline at 0.99% +/- 0.14% (p = 0.0032). CONCLUSIONS: CPB resulted in a small (10%) but significant reduction in the MAC for isoflurane. The mechanism behind this reduction in MAC is not clear but may be related to CPB-induced cerebral injury.

"Other" neurologic complications after cardiac surgery.

Compared to the neurologic morbidity of stroke and cognitive dysfunction, "other" neurologic complications involving injuries to the brachial plexus, phrenic nerve, cranial nerves, other peripheral nerves, as well as the visual pathways, have been disproportionately underrepresented in the cardiac surgery and anesthesiology literature. These injuries are often missed in the early postoperative period when attention is focused principally on recovery from the acute trespass of cardiac surgery and cardiopulmonary bypass. However, when these problems do become apparent, they can cause considerable discomfort and morbidity. An overview of the current concepts of injury mechanisms/etiology, diagnosis, prognosis, and when possible, prevention of these injuries is presented.

Hemodilution during cardiopulmonary bypass increases cerebral infarct volume after middle cerebral artery occlusion in rats.

Although the optimal hematocrit during cardiopulmonary bypass (CPB) is not defined, excessive hemodilution may lead to organ ischemia via a reduction in oxygen-carrying capacity uncompensated by autoregulatory and/or rheologic increases in organ blood flow. As a result, the consequences of hemodilution in patients at risk for cerebral ischemia are not clearly understood. We designed this study to evaluate the effects of hemodilution in the setting of focal cerebral ischemia during CPB. Wistar rats surgically prepared for CPB were randomized to either hemodilution (hemoglobin (Hb), 6 g/dL; n = 9) or control (Hb, 11 g/dL; n = 8) groups and subsequently exposed to focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO). Immediately after the onset of MCAO (maintained for 90 min), 65 min of hypothermic (28 degrees C) CPB was initiated. Twenty-four hours later, functional neurological outcome and cerebral infarct volume were determined. Compared with controls, the hemodilution group had worse neurological performance (new score = 8 [2], hemodilution; versus 10 [2], control; P = 0.030) and larger total cerebral infarct volumes (182 +/- 84 mm(3), hemodilution; versus 103 +/- 58 mm(3), control; P = 0.043). In this experimental model of CPB with reversible MCAO-induced focal cerebral ischemia, hemodilution worsened neurological function and increased cerebral infarct volume.

Intraischemic nitrous oxide alters neither neurologic nor histologic outcome: a comparison with dizocilpine.

N-Methyl-D-aspartate receptor antagonism contributes to the anesthetic action of nitrous oxide (N(2)O). We examined the effects of the N-methyl-D-aspartate antagonists N(2)O and dizocilpine on outcome from filament occlusion of the middle cerebral artery (MCAO). Rats breathed 70% nitrogen/30% oxygen or 70% N(2)O/30% oxygen during MCAO. A third group breathed 70% nitrogen/30% oxygen and was given dizocilpine (0.25 mg/kg IV). After 75 min of MCAO, the rats recovered for 3 or 14 days. Pericranial temperature was maintained at 37.5 degrees C +/- 0.2 degrees C during ischemia and for 20 h postischemia. N(2)O did not alter neurologic scores at 3 days (N(2)O, 21 +/- 6; nitrogen, 22 +/- 8; P = 0.95; 0 = normal; 48 = maximal deficit; mean +/- sd; n = 15) or 14 days (N(2)O, 13 +/- 6; nitrogen, 12 +/- 6; P = 0.93; n = 15-16) postischemia. N(2)O had no effect on infarct size at 3 days (N(2)O, 162 +/- 45 mm(3); nitrogen, 162 +/- 61 mm(3); P > 0.99) or 14 days (N(2)O, 147 +/- 56 mm(3); nitrogen, 151 +/- 62 mm(3); P = 0.99) postischemia. Dizocilpine treatment caused smaller infarcts (3 days: 66 +/- 49 mm(3), P < 0.0001 versus nitrogen; 14 days: 84 +/- 50 mm(3), P < 0.006 versus nitrogen) and reduced the neurologic deficit (3 days: 10 +/- 10, P = 0.002 versus nitrogen; 14 days: 6 +/- 7, P = 0.006 versus nitrogen). N(2)O (70%) had no effect on either behavioral or histologic outcome from transient focal cerebral ischemia when compared with results in rats breathing 70% nitrogen. These results indicate that normobaric N(2)O does not alter the response of rat brain to a focal ischemic insult.

Severe hypotension is not essential for isoflurane neuroprotection against forebrain ischemia in mice.

BACKGROUND: Volatile anesthetics provide protection in experimental models of global cerebral ischemia. To date, all models evaluated have included profound systemic arterial hypotension as a component of the ischemic insult. This study was designed to determine if isoflurane protection persists in a global insult devoid of hypotension. METHODS: C57BL/6J mice having a high incidence of posterior communicating artery atresia were anesthetized with isoflurane (1.2%) or fentanyl/N2O and subjected to bilateral carotid artery occlusion for 15 min or 20 min with normotension (80-110 mmHg mean arterial pressure) or for 10 min with hypotension (35 mmHg mean arterial pressure). Three days later, neurologic function and histologic damage were assessed. Other mice underwent measurement of intraischemic cerebral blood flow (4-iodo-N-methyl-[14C]antipyrine autoradiography) or plasma norepinephrine. RESULTS: Isoflurane reduced the percentage of hippocampal CA1 dead neurons (e.g., 10 min bilateral carotid occlusion + hypotension: 43 +/- 18 (isoflurane) vs. 67 +/- 20 (fentanyl/N2O), P = 0.003; 20 min bilateral carotid occlusion + normotension: 49 +/- 27 (isoflurane) vs. 71 +/- 22 (fentanyl/N2O), P = 0.003). Isoflurane also reduced CA3 damage and improved neurologic function under all conditions. Intraischemic forebrain blood flow was similar during bilateral carotid occlusion plus normotension for the two anesthetic states. Plasma norepinephrine values were greater when hypotension was added to the ischemic insult. CONCLUSIONS: Isoflurane resulted in improved neurologic function and reduced histologic damage regardless of the presence or absence of systemic hypotension during the ischemic insult. This indicates that beneficial effects of isoflurane are most likely attributable to direct effects at the neuronal level as opposed to indirect effects resulting from interactions with profound hypotension.

The neuroprotective effect of xenon administration during transient middle cerebral artery occlusion in mice.

BACKGROUND: Xenon has been shown to be neuroprotective in several models of in vitro and in vivo neuronal injury. However, its putative neuroprotective properties have not been evaluated in focal cerebral ischemia. The purpose of this study was to determine if xenon offers neuroprotection in a mouse model of middle cerebral artery occlusion. METHODS: C57BL/6 mice underwent 60 min of middle cerebral artery occlusion. The animals (n = 21 per group) were randomized to receive either 70% xenon + 30% O2, 70% N2O + 30% O2, or 35% xenon + 35% N2O + 30% O2. After 24 h, functional neurologic outcome (on three independent scales: four-point, general, and focal deficit scales) and cerebral infarct size were evaluated. RESULTS: The 70% xenon + 30% O2 group showed improved functional outcome (median [interquartile range], four-point scale: 2 [2], 70% xenon + 30% O2 versus 3 [2], 70% N2O + 30% O2, P = 0.0061; general deficit scale: 9 [6], 70% xenon + 30% O2 versus 10 [4], 70% N2O + 30% O2, P = 0.0346). Total cerebral infarct volumes were reduced in the 70% xenon + 30% O2 group compared with the 70% N2O + 30% O2 group (45 +/- 17 mm3 versus 59 +/- 11 mm3, respectively; P = 0.0009). CONCLUSIONS: In this model of transient focal cerebral ischemia, xenon administration improved both functional and histologic outcome.