Individualised prediction of resilience and vulnerability to sleep loss using EEG features.

It is well established that individuals differ in their response to sleep loss. However, existing methods to predict an individual's sleep-loss phenotype are not scalable or involve effort-dependent neurobehavioural tests. To overcome these limitations, we sought to predict an individual's level of resilience or vulnerability to sleep loss using electroencephalographic (EEG) features obtained from routine night sleep. To this end, we retrospectively analysed five studies in which 96 healthy young adults (41 women) completed a laboratory baseline-sleep phase followed by a sleep-loss challenge. After classifying subjects into sleep-loss phenotypic groups, we extracted two EEG features from the first sleep cycle (median duration: 1.6 h), slow-wave activity (SWA) power and SWA rise rate, from four channels during the baseline nights. Using these data, we developed two sets of logistic regression classifiers (resilient versus not-resilient and vulnerable versus not-vulnerable) to predict the probability of sleep-loss resilience or vulnerability, respectively, and evaluated model performance using test datasets not used in model development. Consistently, the most predictive features came from the left cerebral hemisphere. For the resilient versus not-resilient classifiers, we obtained an average testing performance of 0.68 for the area under the receiver operating characteristic curve, 0.72 for accuracy, 0.50 for sensitivity, 0.84 for specificity, 0.61 for positive predictive value, and 3.59 for likelihood ratio. We obtained similar performance for the vulnerable versus not-vulnerable classifiers. These results indicate that logistic regression classifiers based on SWA power and SWA rise rate from routine night sleep can largely predict an individual's sleep-loss phenotype.

Electroencephalographic markers from routine sleep discriminate individuals who are vulnerable or resilient to sleep loss.

Sleep loss impairs cognition; however, individuals differ in their response to sleep loss. Current methods to identify an individual's vulnerability to sleep loss involve time-consuming sleep-loss challenges and neurobehavioural tests. Here, we sought to identify electroencephalographic markers of sleep-loss vulnerability obtained from routine night sleep. We retrospectively analysed four studies in which 50 healthy young adults (21 women) completed a laboratory baseline-sleep phase followed by a sleep-loss challenge. After classifying subjects as resilient or vulnerable to sleep loss, we extracted three electroencephalographic features from four channels during the baseline nights, evaluated the discriminatory power of these features using the first two studies (discovery), and assessed reproducibility of the results using the remaining two studies (reproducibility). In the discovery analysis, we found that, compared to resilient subjects, vulnerable subjects exhibited: (1) higher slow-wave activity power in channel O1 (p < 0.0042, corrected for multiple comparisons) and in channels O2 and C3 (p < 0.05, uncorrected); (2) higher slow-wave activity rise rate in channels O1 and O2 (p < 0.05, uncorrected); and (3) lower sleep spindle frequency in channels C3 and C4 (p < 0.05, uncorrected). Our reproducibility analysis confirmed the discovery results on slow-wave activity power and slow-wave activity rise rate, and for these two electroencephalographic features we observed consistent group-difference trends across all four channels in both analyses. The higher slow-wave activity power and slow-wave activity rise rate in vulnerable individuals suggest that they have a persistently higher sleep pressure under normal rested conditions.

The influence of do-not-resuscitate status on the outcomes of patients undergoing emergency vascular operations.

BACKGROUND: Do-not-resuscitate (DNR) orders allow patients to communicate their wishes regarding cardiopulmonary resuscitation. Although DNR status may influence physician decision making regarding resuscitation, the effect of DNR status on outcomes of patients undergoing emergency vascular operation remains unknown. The aim of this study was to analyze the effect of DNR status on the outcomes of emergency vascular surgery. METHODS: The National Surgical Quality Improvement Program database was queried to identify all patients requiring emergency vascular surgical interventions between 2005 and 2010. Demographics, clinical data, and outcomes were extracted. Patients were compared according to DNR status. The primary outcome measure was 30-day mortality. RESULTS: During the study period, 16,678 patients underwent emergency vascular operations (10.8% of the total vascular surgery population). Of those, 548 patients (3.3%) had a DNR status. The differences in rates of open or endovascular repair or of intraoperative blood requirement between the two groups were not significant. After adjusting for differences in demographics and clinical data, DNR patients were more likely to have higher rates of graft failure (8.7% vs 2.4%; adjusted P < .01) and failure to wean from mechanical ventilation (14.9 % vs 9.9%; adjusted P < .001). DNR status was associated with a 2.5-fold rise in 30-day mortality (35.0% vs 14.0%; 95% confidence interval, 1.7-2.9; adjusted P < .001). CONCLUSIONS: The presence of a DNR order was independently associated with mortality. Patient and family counseling on surgical expectations before emergency vascular operations is warranted because the risks of perioperative events are significantly elevated when a DNR order exists.

Trends and outcomes of endovascular therapy in the management of civilian vascular injuries.

OBJECTIVE: The rapid evolution of endovascular surgery has greatly expanded management options for a wide variety of vascular diseases. Endovascular therapy provides a less invasive alternative to open surgery for critically ill patients who have sustained arterial injuries. The purpose of this study was to evaluate recent trends in the management of arterial injuries in the United States with specific reference to the use of endovascular strategies and to examine the outcomes of endovascular vs open therapy for the treatment of civilian arterial traumatic injuries. METHODS: A 9-year analysis of the National Trauma Data Bank was performed to identify all patients who sustained arterial injuries. Demographics, clinical data, interventions, and outcomes were extracted. Propensity scores were used to match endovascular patients to those undergoing open operation. Patient outcomes were compared according to treatment approach. RESULTS: A total of 23,105 patients were available for analysis. Overall, there was a significant increase in the use of endovascular procedures during 9 years (from 0.3% in 2002 to 9.0% in 2010; P < .001), particularly among blunt trauma patients (from 0.4% in 2002 to 13.2% in 2010; P < .001). This increase was noteworthy and dramatic for injuries of the internal iliac artery (from 8.0% in 2002 to 40.3% in 2010; P < .001), thoracic aorta (from 0.5% in 2002 to 21.9% in 2010; P < .001), and common/external iliac arteries (from 0.4% in 2002 to 20.4% in 2010; P < .001). A significant decrease was noted for open procedures (49.1% in 2002 to 45.6%; P < .001), especially for blunt trauma (42.9% in 2002 to 35.8% in 2010; P < .001). There was a stepwise increase in the proportion of patients managed by endovascular therapy as the Injury Severity Score increased (highest in the spectrum Injury Severity Score 31-50). When outcomes were compared between matched patients who underwent endovascular and open procedures, patients who underwent endovascular procedures had significantly lower in-hospital mortality (12.9% vs 22.4%; odds ratio, 0.5; 95% confidence interval, 0.4-0.6; P < .001). Endovascular patients also had decreased rates of sepsis (7.5% vs 5.4%; odds ratio, 0.7; 95% confidence interval, 0.5-0.9; P = .025). CONCLUSIONS: The use of endovascular therapy in the United States has increased dramatically during the last decade, in particular among severely injured blunt trauma patients. Endovascular therapy was associated with improved in-hospital mortality and lower rates of sepsis.

Altered long-range functional connectivity in PTSD: Role of the infraslow oscillations of cortical activity amplitude envelopes.

OBJECTIVE: Coupling between the amplitude envelopes (AEs) of regional cortical activity reflects mechanisms that coordinate the excitability of large-scale cortical networks. We used resting-state MEG recordings to investigate the association between alterations in the coupling of cortical AEs and symptoms of post-traumatic stress disorder (PTSD). METHODS: Participants (n = 96) were service members with combat exposure and various levels of post-traumatic stress severity (PTSS). We assessed the correlation between PTSS and (1) coupling of broadband cortical AEs of beta band activity, (2) coupling of the low- (<0.5 Hz) and high-frequency (>0.5 Hz) components of the AEs, and (3) their time-varying patterns. RESULTS: PTSS was associated with widespread hypoconnectivity assessed from the broadband AE fluctuations, which correlated with subscores for the negative thoughts and feelings/emotional numbing (NTF/EN) and hyperarousal clusters of symptoms. Higher NTF/EN scores were also associated with smaller increases in resting-state functional connectivity (rsFC) with time during the recordings. The distinct patterns of rsFC in PTSD were primarily due to differences in the coupling of low-frequency (infraslow) fluctuations of the AEs of beta band activity. CONCLUSIONS: Our findings implicate the mechanisms underlying the regulation/coupling of infraslow oscillations in the alterations of rsFC assessed from broadband AEs and in PTSD symptomatology. SIGNIFICANCE: Altered coordination of infraslow amplitude fluctuations across large-scale cortical networks can contribute to network dysfunction and may provide a target for treatment in PTSD.

Cognitive flexibility in post-traumatic stress disorder: Sustained interference associated with altered modulation of cortical oscillatory activity during task-switching.

Post-traumatic stress disorder (PTSD) is associated with deficits in cognitive flexibility, with evidence suggesting that these deficits may be a risk factor for the development of core PTSD symptoms. Understanding the neurophysiological substrate of this association could aid the development of effective therapies for PTSD. In this study, we investigated the relationship between post-traumatic stress severity (PTSS) in service members with combat exposure and the modulation of cortical oscillatory activity during a test of cognitive flexibility. Participants were assigned to three groups based on PTSS scores: low (well below a threshold consistent with a diagnosis of PTSD, n = 30), moderate (n = 32), and high (n = 29) symptom severity. Magnetoencephalography data were recorded while participants performed a cued rule-switching task in which two matching rules were repeated or switched across consecutive trials. Participants with high PTSS had longer reaction times for both switch and repeat trials, and showed evidence of sustained residual interference during repeat trials. During the cue-stimulus interval, participants with moderate and high PTSS showed higher relative theta power in switch trials over left dorsolateral prefrontal cortex (DLPFC). After test-stimulus onset, participants with high PTSS showed less suppression of beta band activity, which was present over multiple prefrontal, parietal, and temporal regions in switch trials, but it was confined to ventromedial prefrontal cortex in repeat trials. Higher theta band activity is a marker of effortful voluntary shifting of attention, while lower suppression of beta band activity reflects difficulties with inhibition of competing perceptual information and courses of action. These findings are consistent with a role for altered suppression of beta band activity, which can be due to less effective top-down bias signals exerted by DLPFC, in the etiology of cognitive flexibility deficits in PTSD.

The natural history of duplex-detected stenosis after femoropopliteal endovascular therapy suggests questionable clinical utility of routine duplex surveillance.

OBJECTIVE: Duplex ultrasound (DU) surveillance (DUS) criteria for vein graft stenosis and thresholds for reintervention are well established. The natural history of DU-detected stenosis and the threshold criteria for reintervention in patients undergoing endovascular therapy (EVT) of the femoropopliteal system have yet to be determined. We report an analysis of routine DUS after infrainguinal EVT. METHODS: Consecutive patients undergoing EVT of the superficial femoral artery (SFA) or popliteal artery were prospectively enrolled in a DUS protocol (≤1 week after intervention, then at 3, 6, and 12 months thereafter). Peak systolic velocity (PSV) and velocity ratio (Vr) were used to categorize the treated artery: normal was PSV <200 cm/s and Vr <2, moderate stenosis was PSV = 200-300 cm/s or Vr = 2-3, and severe stenosis was PSV >300 cm/s or Vr >3. Reinterventions were generally performed for persistent or recurrent symptoms, allowing us to analyze the natural history of DU-detected lesions and to perform sensitivity and specificity analysis for DUS criteria predictive of failure. RESULTS: Ninety-four limbs (85 patients) underwent EVT for SFA-popliteal disease and were prospectively enrolled in a DUS protocol. The initial scans were normal in 61 limbs (65%), and serial DU results remained normal in 38 (62%). In 17 limbs (28%), progressive stenoses were detected during surveillance. The rate of thrombosis in this subgroup was 10%. Moderate stenoses were detected in 28 (30%) limbs at initial scans; of these, 39% resolved or stabilized, 47% progressed to severe, and occlusions developed in 14%. Five (5%) limbs harbored severe stenoses on initial scans, and 80% of lesions resolved or stabilized. Progression to occlusion occurred in one limb (20%). The last DUS showed 25 limbs harbored severe stenoses; of these, 13 (52%) were in symptomatic patients and thus required reintervention regardless of DU findings. Eleven limbs (11%) eventually occluded. Sensitivity and specificity of DUS to predict occlusion were 88% and 60%, respectively. CONCLUSIONS: DUS does not reliably predict arterial occlusion after EVT. Stenosis after EVT appears to have a different natural history than restenosis after vein graft bypass. EVT patients are more likely to have severe stenosis when they present with recurrent symptoms, in contrast to vein graft patients, who commonly have occluded grafts when they present with recurrent symptoms. The potential impact of routine DU-directed reintervention in patients after EVT is questionable. The natural history of DU-detected stenosis after femoropopliteal endovascular therapy suggests questionable clinical utility of routine DUS.

A Systems Approach to Behavioral Neurobiology: Integrating Psychodynamics and Neuroscience in a Psychiatric Curriculum.

In the practice of medicine, an understanding of the biological functioning of organs and organ systems is the basis for theories of pathology and clinical practice. If psychoanalysis is to be accepted by the medical and psychiatric community, it must be based on a sophisticated understanding of the organ from which mental and emotional experiences emanate and use scientifically acceptable language. Each approach to psychotherapy has its own vocabulary for describing neuropsychological processes. Neurobiological vocabulary provides the various factions "neutral ground" upon which to carry on a multidisciplinary integrative dialogue. An understanding of behavioral neuroscience allows the therapist to look beyond the labels that spawn division and identify unifying biological principles that are described in a variety of ways in a multitude of theories. We contend that the neural network/representational approach to neurobiology views human mental experience as the result of multiple complex integrated systems, and is therefore holistic and antireductionistic in its perspective. Such a biologically informed psychotherapy facilitates integration of skill sets and flexibility in technique. With these principles in mind, the therapist can base his or her approach to the patient based on these principles rather than on devotion to one particular "school" or another. Because behavioral neuroscience supports many of the basic tenets of psychoanalytic theory, such an integrative psychotherapy would be psychody-namically informed. In this paper, we outline some of the ideas we present in our neuroscience course and how we relate biological concepts with some core principles of psychodynamics and psychotherapy.

Quantifying the effects of sleep loss: relative effect sizes of the psychomotor vigilance test, multiple sleep latency test, and maintenance of wakefulness test.

The psychomotor vigilance test (PVT) is a widely-used, minimally invasive, inexpensive, portable, and easy to administer behavioral measure of vigilance that is sensitive to sleep loss. We conducted analyses to determine the relative sensitivity of the PVT vs. the multiple sleep latency test (MSLT) and the maintenance of wakefulness test (MWT) during acute total sleep deprivation (TSD) and multiple days of sleep restriction (SR) in studies of healthy adults. Twenty-four studies met the criteria for inclusion. Since sleepiness countermeasures were administered in some of these studies, the relative sensitivity of the three measures to these interventions was also assessed. The difference in weighted effect size (eta-squared) was computed for each pair of sleepiness measures based on available raw test data (such as average PVT reaction time). Analyses revealed that the sleep measures were differentially sensitive to various types of sleep loss over time, with MSLT and MWT more sensitive to TSD than the PVT. However, sensitivity to SR was comparable for all three measures. The PVT and MSLT were found to be differentially sensitive to the administration of sleepiness countermeasures (drugs, sleep loss, etc.), but PVT and MWT were found to be comparably sensitive to these interventions. These findings suggest the potential utility of the PVT as a component of next-generation fatigue risk management systems.

Post-traumatic stress disorder is associated with alterations in evoked cortical activation during visual recognition of scenes.

We recorded magnetoencephalography data during a visual recognition task in participants with combat exposure (n = 40, age: 41.2 ± 7.2 years) to investigate the relationship between the evoked brain activity, behavioral performance, and the severity of their post-traumatic stress symptoms assessed using the PTSD Check List for DSM V version (PCL-5). In an initial study session, participants were presented with a series of images of outdoor scenes and were instructed to study the images for an upcoming recognition test. In a subsequent session, the original images were shown intermixed with novel images while participants performed the recognition task. PCL-5 scores were negatively correlated with discrimination performance and with the recognition accuracy for original images. During the recognition session, higher PCL-5 scores were associated with reduced relative power of the evoked response to original images from 100 ms to 300 ms following the image onset over a distributed brain network including the bilateral inferior frontal gyri, left middle frontal gyrus, left supramarginal gyrus, right precuneus and the bilateral superior temporal gyri. These findings indicate that the lower recognition performance in participants with higher PTSD symptom severity is associated with altered cortical activity in brain regions that are known to play a role in the elaboration on visual cues that supports recollection.

Altered modulation of beta band oscillations during memory encoding is predictive of lower subsequent recognition performance in post-traumatic stress disorder.

We studied the relationship between electrophysiological markers of memory encoding, subsequent recognition performance, and severity of PTSD symptoms in service members with combat exposure (n = 40, age: 41.2 ± 7.2 years) and various levels of PTSD symptom severity assessed using the PTSD Check List for DSM V version (PCL-5). Brain activity was recorded using magnetoencephalography during a serial presentation of 86 images of outdoor scenes that were studied by participants for an upcoming recognition test. In a second session, the original images were shown intermixed with an equal number of novel images while participants performed the recognition task. Participants recognized 76.0% ± 12.1% of the original images and correctly categorized as novel 89.9% ± 7.0% of the novel images. A negative correlation was present between PCL-5 scores and discrimination performance (Spearman rs = -0.38, p = 0.016). PCL-5 scores were also negatively correlated with the recognition accuracy for original images (rs = -0.37, p = 0.02). Increases in theta and gamma power and decreases in alpha and beta power were observed over distributed brain networks during memory encoding. Higher PCL-5 scores were associated with less suppression of beta band power in bilateral ventral and medial temporal regions and in the left orbitofrontal cortex. These regions also showed positive correlations between the magnitude of suppression of beta power during encoding and subsequent recognition accuracy. These findings indicate that the lower recognition performance in participants with greater PTSD symptom severity may be due in part to ineffective encoding reflected in altered modulation of beta band oscillatory activity.

Functional and Structural Neuroimaging Correlates of Repetitive Low-Level Blast Exposure in Career Breachers.

Combat military and civilian law enforcement personnel may be exposed to repetitive low-intensity blast events during training and operations. Persons who use explosives to gain entry (i.e., breach) into buildings are known as "breachers" or dynamic entry personnel. Breachers operate under the guidance of established safety protocols, but despite these precautions, breachers who are exposed to low-level blast throughout their careers frequently report performance deficits and symptoms to healthcare providers. Although little is known about the etiology linking blast exposure to clinical symptoms in humans, animal studies demonstrate network-level changes in brain function, alterations in brain morphology, vascular and inflammatory changes, hearing loss, and even alterations in gene expression after repeated blast exposure. To explore whether similar effects occur in humans, we collected a comprehensive data battery from 20 experienced breachers exposed to blast throughout their careers and 14 military and law enforcement controls. This battery included neuropsychological assessments, blood biomarkers, and magnetic resonance imaging measures, including cortical thickness, diffusion tensor imaging of white matter, functional connectivity, and perfusion. To better understand the relationship between repetitive low-level blast exposure and behavioral and imaging differences in humans, we analyzed the data using similarity-driven multi-view linear reconstruction (SiMLR). SiMLR is specifically designed for multiple modality statistical integration using dimensionality-reduction techniques for studies with high-dimensional, yet sparse, data (i.e., low number of subjects and many data per subject). We identify significant group effects in these data spanning brain structure, function, and blood biomarkers.

Aortic stent-graft explantation in a kidney transplant recipient.

AAA repair in renal transplant recipients has generated a variety of methods of managing the allograft. Endovascular techniques have been successfully employed in this patient population. Due to inherent limitations of present endovascular methods, occasional stent-graft excision must be performed. We present a case of aortic stent-graft excision in a renal transplant recipient using a pump-oxygenator to maintain allograft perfusion.

Aortoiliac aneurysm repair in kidney transplant recipients.

A potential problem during endovascular aortic aneurysm repair (EVAR) or open repair in renal allograft patients is ischemia of the transplanted kidney. In this study, kidney transplant patients who underwent aortic aneurysm repair in our institution were added to similar cases extracted from the literature to represent the basis of this work. Comparisons between patients treated with open surgery versus EVAR were performed in terms of renal function. In the EVAR group, most aneurysms were infrarenal, and 84% were treated with modular bifurcated devices. Protective kidney allograft perfusion measures were not used. The pre- and postoperative Cr was 1.69 and 1.73 mg/dL, respectively (P = .412). All EVAR patients had good outcomes. Complications included 8 endoleaks and 1 limb ischemia case. Three patients died from aortic repair-unrelated reasons. In the open group, the pre-and postoperative Cr was 1.45 and 1.37 mg/dL, respectively (P = .055). Most cases were infrarenal and mostly treated by aortobiiliac bypasses. In 16%, no adjuvant allograft perfusion was provided. In the rest, temporary axillofemoral bypasses were used most often. Most outcomes were favorable (57%). Reported procedural-related complications included arterial embolism, wound infection, and pneumonia. Deaths were reported in 5 occasions (none allograft failure dependent). No differences in Cr between EVAR and open techniques (P = .13) were seen. Aneurysm repair in kidney transplant recipients is associated with excellent renal preservation. Adverse outcomes were all allograft failure independent in both groups. EVAR without special allograft protection measures seems to be equally effective as open surgery with or without adjuvant kidney transplant perfusion.

Post-traumatic stress disorder is associated with altered modulation of prefrontal alpha band oscillations during working memory.

OBJECTIVE: To investigate the relationship between the severity of PTSD symptoms, modulation of alpha band oscillations, and behavioral performance in a working memory task. METHODS: Magnetoencephalography data were recorded in 35 participants with combat exposure and various degrees of PTSD symptom severity while they performed a modified Sternberg working memory task: briefly presented sets of two or six letters had to be held in memory and participants indicated whether subsequent probe letters were present or absent from these sets. RESULTS: PTSD scores were positively correlated with the false positive rate in the high memory load condition. Higher rates of false recognition were associated with negative probes that were seen in recent previous trials (negative probe recency effect) or were physically similar with the list letters. The relative alpha band power in the left middle frontal gyrus was negatively correlated with both PTSD scores and false positive rates. CONCLUSIONS: Reduced task specific modulation of alpha band oscillations in left middle frontal cortex may reflect alterations in the functions of pattern separation and suppression of memory traces for irrelevant or no longer relevant information in PTSD. SIGNIFICANCE: The lower amplitude of prefrontal alpha band oscillations may represent an important physiological basis for core PTSD symptoms and can provide a target for interventions to augment response to treatment.

Superficial femoral artery thrombosis as a cause for distal embolism in primary antiphospholipid syndrome.

Antiphospholipid syndrome is a diagnosis with the clinical manifestations of thromboses in the presence of an antiphospholipid antibody. A 25-year-old man with a history of deep venous thrombosis, pulmonary emboli, and myocardial infarction, and receiving long-term anticoagulation with warfarin, all due to primary antiphospholipid syndrome, presented with blue toe syndrome from a primary superficial femoral artery thrombus. He was anticoagulated with fondaparinux in addition to dipyridamole and aspirin perioperatively. The area of thrombus was resected and reconstructed using a cephalic vein interposition graft. This report reviews antiphospholipid syndrome and identifies potential questions and problems relating to a rare clinical presentation.

Functional MRI of the primary somatosensory cortex in extinction to simultaneous bilateral tactile stimuli due to right temporal lobe stroke.

Patients with right posterior temporoparietal cortical lesions often exhibit extinction to tactile double simultaneous stimuli (EDSS). It is not known whether sensory unawareness-extinction results from suppression of sensory input into the somatosensory cortex (SI), inhibition of SI, or interference which prevents SI output from activating and being fully processed by association areas. A patient with EDSS due to a right temporal stroke sparing SI and posterior parietal cortex and eight age-matched healthy controls were studied with fMRI during tactile stimulation. The volume of activation of SI during tactile stimulation of the right hand, the left hand and both hands was measured and the patient's volume of activation was compared to that of the control subjects in each of these stimulus conditions. Although the patient demonstrated behavioral EDSS, during fMRI the patient's activation of SI on both sides was within the range of the control participants' volumes of activation. These findings suggest that EDSS in patients with a right temporal lobe stroke results from processing abnormalities that occur after these afferent tactile stimuli are processed by SI.

Measure what matters: institutional outcome data are superior to the use of surrogate markers to define "center of excellence" for abdominal aortic aneurysm repair.

Outcome analysis is increasingly being used to develop health-care policy and direct patient referral. For example, the Leapfrog Group health-care quality initiative has proposed "evidence-based hospital" referral criteria for specific procedures including elective abdominal aortic aneurysm repair (AAA-R). These criteria include an annual hospital AAA operative volume exceeding 50 cases and provision of intensive care unit (ICU) care by board-certified intensivists. Outcomes after AAA-R are reportedly influenced by presentation (intact vs. ruptured), operative approach (endovascular vs. open, transperitoneal vs. retroperitoneal), surgeon subspecialty, case volume (hospital and surgeon), and provision of postoperative care by an intensivist. The purpose of this study was to compare our single-center results with those of high-volume centers to assess the validity of the concept that surrogate markers, such as case volume or intensivist involvement, can be used to estimate procedural outcome. A retrospective review was performed of AAA-Rs at one low-volume academic medical center from January 1994 to March 2005. Demographic data, aneurysm diameter and location, operative indications, and repair approach were documented. Postoperative complications, mortality rates, and hospital and ICU length of stay (LOS) were noted and compared to established benchmarks. During the study period, 270 patients underwent AAA-R (annual mean = 27 hospital cases and 13.4 cases/attending vascular surgeon). ICU care was provided by a dedicated vascular surgery service without routine intensivist involvement. Open, elective, infrarenal AAA-R was performed in 161 patients (60%), with a 2.5% hospital mortality rate (30-day, 3.1%). Thirty-three (12%) patients underwent elective endovascular aneurysm repair (EVAR), with no mortality. Both ICU (3.7 vs. 1.4 days, p = 0.03) and hospital (9.2 vs. 2.8 days, p = 0.002) LOS were significantly reduced after EVAR compared to open repair. Hospital LOS was significantly lower after open retroperitoneal repair compared to transperitoneal repair (6.1 vs. 10.3 days, p = 0.001). Thirty-five patients (13%) underwent ruptured AAA-R, with only 34.3% mortality (in-hospital and 30-day). Forty-one patients (15%) underwent repair of complex aortic aneurysms, with 14.1% mortality. There are increasing societal and economic pressures to direct patient referrals to "centers of excellence" for specific surgical procedures. Although our institution meets neither of the Leapfrog Group's proposed criteria, our mortality and LOS for both intact and ruptured infrarenal AAA-R are equivalent or superior to published benchmarks for high-volume hospitals. Individual institutional outcome results such as these suggest that patient referral and care should be based upon actual, carefully verified outcome data rather than utilization of surrogate markers such as case volume and subspecialist involvement in postoperative care.

Network model of decreased context utilization in autism spectrum disorder.

Individuals with autism spectrum disorders (ASD) demonstrate impaired utilization of context, which allows for superior performance on the "false memory" task. We report the application of a simplified parallel distributed processing model of context utilization to the false memory task. For individuals without ASD, experiments support a model wherein presentation of one word, e.g., ''apple,'' strongly activates the neighboring nodes of closely related words such as ''fruit,'' ''tree,'' whereas in ASD these neighboring nodes are relatively less activated. We demonstrate this model to be consistent with the superior performance on recognition testing on the false memory test, but not on free recall. This may have an anatomic basis in diminished hippocampal neuronal arborization and the abnormal minicolumnar pathology in ASD.

Portomesenteric reconstruction during Whipple procedures: review and report of a case.

A 60-year-old man undergoing a Whipple procedure to treat a pancreatic cancer was found to have tumor adherence to the portal vein. An en block pancreaticoduodenectomy with segmental portal vein resection (PVR) was performed. A primary portal vein anastomosis was initially attempted but failed. Hemodynamic deterioration led the authors to perform a temporary prosthetic portal vein interposition graft and abdominal closure. The following morning, once stable, the patient was brought back to the operating room for autologous reconstruction with femoral vein and completion of the pancreaticoduodenectomy. The role of PVR for vein invasion or tumor adherence during a Whipple procedure is still under debate. However, there is growing evidence that the perioperative morbidity and long-term survival in patients who undergo a pancreaticoduodenectomy with PVR are similar to those of patients without vein resection. Therefore a combined resection of the pancreatic head and the portal vein has been suggested in the absence of other contraindications for resection to be able to offer a curative surgical intervention to a larger number of patients. The authors herein report the details of a patient's case and also review the currently available methods for PVR and reconstruction.