Lung preservation: from perfusion to temperature.

PURPOSE OF REVIEW: This article will review the evidence behind elements of the lung preservation process that have remained relatively stable over the past decade as well as summarize recent developments in ex-vivo lung perfusion and new research challenging the standard temperature for static cold storage. RECENT FINDINGS: Ex-vivo lung perfusion is becoming an increasingly well established means to facilitate greater travel distance and allow for continued reassessment of marginal donor lungs. Preliminary reports of the use of normothermic regional perfusion to allow utilization of lungs after DCD recovery exist, but further research is needed to determine its ability to improve upon the current method of DCD lung recovery. Also, research from the University of Toronto is re-assessing the optimal temperature for static cold storage; pilot studies suggest it is a feasible means to allow for storage of lungs overnight to allow for daytime transplantation, but ongoing research is awaited to determine if outcomes are superior to traditional static cold storage. SUMMARY: It is crucial to understand the fundamental principles of organ preservation to ensure optimal lung function posttransplant. Recent advances in the past several years have the potential to challenge standards of the past decade and reshape how lung transplantation is performed.

Tracheostomy management in patients with severe acute respiratory distress syndrome receiving extracorporeal membrane oxygenation: an International Multicenter Retrospective Study.

BACKGROUND: Current practices regarding tracheostomy in patients treated with extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome are unknown. Our objectives were to assess the prevalence and the association between the timing of tracheostomy (during or after ECMO weaning) and related complications, sedative, and analgesic use. METHODS: International, multicenter, retrospective study in four large volume ECMO centers during a 9-year period. RESULTS: Of the 1,168 patients treated with ECMO for severe ARDS (age 48 ± 16 years, 76% male, SAPS II score 51 ± 18) during the enrollment period, 353 (30%) and 177 (15%) underwent tracheostomy placement during or after ECMO, respectively. Severe complications were uncommon in both groups. Local bleeding within 24 h of tracheostomy was four times more frequent during ECMO (25 vs 7% after ECMO, p < 0.01). Cumulative sedative consumption decreased more rapidly after the procedure with sedative doses almost negligible 48-72 h later, when tracheostomy was performed after ECMO decannulation (p < 0.01). A significantly increased level of consciousness was observed within 72 h after tracheostomy in the "after ECMO" group, whereas it was unchanged in the "during-ECMO" group. CONCLUSION: In contrast to patients undergoing tracheostomy after ECMO decannulation, tracheostomy during ECMO was neither associated with a decrease in sedation and analgesia levels nor with an increase in the level of consciousness. This finding together with a higher risk of local bleeding in the days following the procedure reinforces the need for a case-by-case discussion on the balance between risks and benefits of tracheotomy when performed during ECMO.

Extracorporeal Carbon Dioxide Removal in the Treatment of Status Asthmaticus.

OBJECTIVES: Venovenous extracorporeal carbon dioxide removal may be lifesaving in the setting of status asthmaticus. DESIGN: Retrospective review. SETTING: Medical ICU. PATIENTS: Twenty-six adult patients with status asthmaticus treated with venovenous extracorporeal carbon dioxide removal. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic data and characteristics of current and prior asthma treatments were obtained from the electronic medical record. Mechanical ventilator settings, arterial blood gases, vital signs, and use of vasopressors were collected from the closest time prior to cannulation and 24 hours after initiation of extracorporeal carbon dioxide removal. Extracorporeal carbon dioxide removal settings, including blood flow and sweep gas flow, were collected at 24 hours after initiation of extracorporeal carbon dioxide removal. Outcome measures included rates of survival to hospital discharge, ICU and hospital lengths of stay, duration of invasive mechanical ventilation and extracorporeal carbon dioxide removal support, and complications during extracorporeal carbon dioxide removal. Following the initiation of extracorporeal carbon dioxide removal, blood gas values were significantly improved at 24 hours, as were peak airway pressures, intrinsic positive end-expiratory pressure, and use of vasopressors. Survival to hospital discharge was 100%. Twenty patients (76.9%) were successfully extubated while receiving extracorporeal carbon dioxide removal support; none required reintubation. The most common complication was cannula-associated deep venous thrombosis (six patients, 23.1%). Four patients (15.4%) experienced bleeding that required a transfusion of packed RBCs. CONCLUSIONS: In the largest series to date, use of venovenous extracorporeal carbon dioxide removal in patients with status asthmaticus can provide a lifesaving means of support until the resolution of the exacerbation, with an acceptably low rate of complications. Early extubation in select patients receiving extracorporeal carbon dioxide removal is safe and feasible and avoids the deleterious effects of positive-pressure mechanical ventilation in this patient population.

Pregnancy-Induced Sensitization Promotes Sex Disparity in Living Donor Kidney Transplantation.

The presence of sex disparity in living donor kidney transplantation (LDKT) remains controversial. To determine if women fall behind men in LDKT evaluation, we performed an intention to treat study of 2587 candidates listed for kidney transplant at a single transplant center over 7 years. We found that women and men kidney transplant candidates engaged an equivalent type and number of prospective living donors. However, sex-specific differences in sensitization history and histocompatibility reduced the rate of LDKT for women by 30%. Pregnancy-induced incompatibility with spouse donors was limiting given that spouses were among the individuals most likely to complete donation. Notably, participation in a kidney paired exchange program eliminated sex-based differences in LDKT. Collectively, these data suggest that pregnancy is a formidable biologic barrier for women and contributes uniquely to sex disparity in LDKT. Targeted efforts to improve transplant center participation in paired kidney exchanges may increase sex equity in LDKT.

The differentiation of iconic and metaphoric gestures: common and unique integration processes.

Recent research on the neural integration of speech and gesture has examined either gesture in the context of concrete [iconic (IC) gestures] or abstract sentence content [metaphoric (MP) gestures]. However, there has not yet been a direct comparison of the processing of both gesture types. This study tested the theory that left posterior temporal and inferior frontal brain regions are each uniquely involved in the integration of IC and MP gestures. During fMRI-data acquisition, participants were shown videos of an actor performing IC and MP gestures and associated sentences. An isolated gesture (G) and isolated sentence condition (S) were included to separate unimodal from bimodal effects at the neural level. During IC conditions, we found increased activity in the left posterior middle temporal gyrus and its right hemispheric homologue. The same regions in addition to the left inferior frontal gyrus (IFG) were activated during MP conditions in contrast to the isolated conditions (G&S). These findings support the hypothesis that there are distinct integration processes for IC and MP gestures. In line with recent claims of the semantic unification theory, there seems to be a division between perceptual-matching processes within the posterior temporal lobe and higher-order relational processes within the IFG.

Weight loss interventions for morbidly obese patients with compensated cirrhosis: a Markov decision analysis model.

Many transplant centers require that patients maintain a BMI below 40 kg/m(2) in order to be eligible for listing, rendering many morbidly obese patients with end-stage liver disease unable to access liver transplantation as a method of treatment. In order to determine the safest and most efficacious weight loss regimen in this challenging population, Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), and diet and exercise were modeled to assess their impact on life expectancy in morbidly obese patients with cirrhosis. A Markov state transition model was developed to assess the survival benefit of undergoing RYGB, AGB, or 1 year of diet and exercise in morbidly obese patients with compensated cirrhosis. A base case analysis of no weight loss intervention in a 45-year-old patient with compensated cirrhosis and a BMI of 45 kg/m(2) revealed an average survival of 7.93 years. The average survival for the weight loss simulations was 9.14, 8.84, and 8.16 years for RYGB, AGB, and diet and exercise, respectively. In morbidly obese patients with compensated cirrhosis, RYGB allows patients to lose more weight more rapidly than is probable with either AGB or diet and exercise, thus having the greatest impact on survival.

The specificity of action knowledge in sensory and motor systems.

Neuroimaging studies have found that sensorimotor systems are engaged when participants observe actions or comprehend action language. However, most of these studies have asked the binary question of whether action concepts are embodied or not, rather than whether sensory and motor areas of the brain contain graded amounts of information during putative action simulations. To address this question, we used repetition suppression (RS) functional magnetic resonance imaging to determine if functionally-localized motor movement and visual motion regions-of-interest (ROI) and two anatomical ROIs (inferior frontal gyrus, IFG; left posterior middle temporal gyrus, pMTG) were sensitive to changes in the exemplar (e.g., two different people "kicking") or representational format (e.g., photograph or schematic drawing of someone "kicking") within pairs of action images. We also investigated whether concrete versus more symbolic depictions of actions (i.e., photographs or schematic drawings) yielded different patterns of activation throughout the brain. We found that during a conceptual task, sensory and motor systems represent actions at different levels of specificity. While the visual motion ROI did not exhibit RS to different exemplars of the same action or to the same action depicted by different formats, the motor movement ROI did. These effects are consistent with "person-specific" action simulations: if the motor system is recruited for action understanding, it does so by activating one's own motor program for an action. We also observed significant repetition enhancement within the IFG ROI to different exemplars or formats of the same action, a result that may indicate additional cognitive processing on these trials. Finally, we found that the recruitment of posterior brain regions by action concepts depends on the format of the input: left lateral occipital cortex and right supramarginal gyrus responded more strongly to symbolic depictions of actions than concrete ones.

Language, perception, and the schematic representation of spatial relations.

Schemas are abstract nonverbal representations that parsimoniously depict spatial relations. Despite their ubiquitous use in maps and diagrams, little is known about their neural instantiation. We sought to determine the extent to which schematic representations are neurally distinguished from language on the one hand, and from rich perceptual representations on the other. In patients with either left hemisphere damage or right hemisphere damage, a battery of matching tasks depicting categorical spatial relations was used to probe for the comprehension of basic spatial concepts across distinct representational formats (words, pictures, and schemas). Left hemisphere patients underperformed right hemisphere patients across all tasks. However, focused residual analyses using voxel-based lesion-symptom mapping (VLSM) suggest that (1) left hemisphere deficits in the representation of categorical spatial relations are difficult to distinguish from deficits in naming these relations and (2) the right hemisphere plays a special role in extracting schematic representations from richly textured pictures.

The right hemisphere in esthetic perception.

Little about the neuropsychology of art perception and evaluation is known. Most neuropsychological approaches to art have focused on art production and have been anecdotal and qualitative. The field is in desperate need of quantitative methods if it is to advance. Here, we combine a quantitative approach to the assessment of art with modern voxel-lesion-symptom-mapping methods to determine brain-behavior relationships in art perception. We hypothesized that perception of different attributes of art are likely to be disrupted by damage to different regions of the brain. Twenty participants with right hemisphere damage were given the Assessment of Art Attributes, which is designed to quantify judgments of descriptive attributes of visual art. Each participant rated 24 paintings on 6 conceptual attributes (depictive accuracy, abstractness, emotion, symbolism, realism, and animacy) and 6 perceptual attributes (depth, color temperature, color saturation, balance, stroke, and simplicity) and their interest in and preference for these paintings. Deviation scores were obtained for each brain-damaged participant for each attribute based on correlations with group average ratings from 30 age-matched healthy participants. Right hemisphere damage affected participants' judgments of abstractness, accuracy, and stroke quality. Damage to areas within different parts of the frontal parietal and lateral temporal cortices produced deviation in judgments in four of six conceptual attributes (abstractness, symbolism, realism, and animacy). Of the formal attributes, only depth was affected by inferior prefrontal damage. No areas of brain damage were associated with deviations in interestingness or preference judgments. The perception of conceptual and formal attributes in artwork may in part dissociate from each other and from evaluative judgments. More generally, this approach demonstrates the feasibility of quantitative approaches to the neuropsychology of art.

A sinister bias for calling fouls in soccer.

Distinguishing between a fair and unfair tackle in soccer can be difficult. For referees, choosing to call a foul often requires a decision despite some level of ambiguity. We were interested in whether a well documented perceptual-motor bias associated with reading direction influenced foul judgments. Prior studies have shown that readers of left-to-right languages tend to think of prototypical events as unfolding concordantly, from left-to-right in space. It follows that events moving from right-to-left should be perceived as atypical and relatively debased. In an experiment using a go/no-go task and photographs taken from real games, participants made more foul calls for pictures depicting left-moving events compared to pictures depicting right-moving events. These data suggest that two referees watching the same play from distinct vantage points may be differentially predisposed to call a foul.