Eva Rivas

A Role for the Default Mode Network in the Bases of Disorders of Consciousness

Functional connectivity in the default mode network (DMN) is known to be reduced in patients with disorders of consciousness, to a different extent depending on their clinical severity. Nevertheless, the integrity of the structural architecture supporting this network and its relation with the exhibited functional disconnections are very poorly understood. We investigated the structural connectivity and white matter integrity of the DMN in patients with disorders of consciousness of varying clinical severity.

Combination of diffusion tensor and functional magnetic resonance imaging during recovery from the vegetative state

BackgroundThe rate of recovery from the vegetative state (VS) is low. Currently, little is known of the mechanisms and cerebral changes that accompany those relatively rare cases of good recovery. Here, we combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to study the evolution of one VS patient at one month post-ictus and again twelve months later when he had recovered consciousness.MethodsfMRI was used to investigate cortical responses to passive language stimulation as well as task-induced deactivations related to the default-mode network. DTI was used to assess the integrity of the global white matter and the arcuate fasciculus. We also performed a neuropsychological assessment at the time of the second MRI examination in order to characterize the profile of cognitive deficits.ResultsfMRI analysis revealed anatomically appropriate activation to speech in both the first and the second scans but a reduced pattern of task-induced deactivations in the first scan. In the second scan, following the recovery of consciousness, this pattern became more similar to that classically described for the default-mode network. DTI analysis revealed relative preservation of the arcuate fasciculus and of the global normal-appearing white matter at both time points. The neuropsychological assessment revealed recovery of receptive linguistic functioning by 12-months post-ictus.ConclusionsThese results suggest that the combination of different structural and functional imaging modalities may provide a powerful means for assessing the mechanisms involved in the recovery from the VS.

Ventilation/Perfusion Distribution Abnormalities In Morbidly Obese Subjects Before and After Bariatric Surgery

BACKGROUND Obesity is a global and growing public health problem. Bariatric surgery (BS) is indicated in patients with morbid obesity. To our knowledge, the effects of morbid obesity and BS on ventilation/perfusion (V.a/Q.) ratio distributions using the multiple inert gas elimination technique have never before been explored. METHODS We compared respiratory and inert gas (V.a/Q. ratio distributions) pulmonary gas exchange, breathing both ambient air and 100% oxygen, in 19 morbidly obese women (BMI, 45 kg/m2), both before and 1 year after BS, and in eight normal-weight, never smoker, age-matched, healthy women. RESULTS Before BS, morbidly obese individuals had reduced arterial Po2 (76 ± 2 mm Hg) and an increased alveolar-arterial Po2 difference (27 ± 2 mm Hg) caused by small amounts of shunt (4.3% ± 1.1% of cardiac output), along with abnormally broadly unimodal blood flow dispersion (0.83 ± 0.06). During 100% oxygen breathing, shunt increased twofold in parallel with a reduction of blood flow to low V.a/Q. units, suggesting the development of reabsorption atelectasis without reversion of hypoxic pulmonary vasoconstriction. After BS, body weight was reduced significantly (BMI, 31 kg/m2), and pulmonary gas exchange abnormalities were decreased. CONCLUSIONS Morbid obesity is associated with mild to moderate shunt and V.a/Q. imbalance. These abnormalities are reduced after BS.

The systemic inflammome of severe obesity before and after bariatric surgery

Introduction Obesity is associated with low-grade systemic inflammation. The “inflammome” is a network layout of the inflammatory pattern. The systemic inflammome of obesity has not been described as yet. We hypothesized that it can be significantly worsened by smoking and other comorbidities frequently associated with obesity, and ameliorated by bariatric surgery (BS). Besides, whether or not these changes are mirrored in the lungs is unknown, but obesity is often associated with pulmonary inflammation and bronchial hyperresponsiveness. Objectives We sought to: (1) describe the systemic inflammome of morbid obesity; (2) investigate the effects of sex, smoking, sleep apnea syndrome, metabolic syndrome and BS upon this systemic inflammome; and, (3) determine their interplay with pulmonary inflammation. Methods We studied 129 morbidly obese patients (96 females; age 46±12 years; body mass index [BMI], 46±6 kg/m2) before and one year after BS, and 20 healthy, never-smokers, (43±7 years), with normal BMI and spirometry. Results Before BS, compared with controls, all obese subjects displayed a strong and coordinated (inflammome) systemic inflammatory response (adiponectin, C-reactive protein, interleukin (IL)-8, IL-10, leptin, soluble tumor necrosis factor-receptor 1(sTNF-R1), and 8-isoprostane). This inflammome was not modified by sex, smoking, or coexistence of obstructive sleep apnea and/or metabolic syndrome. By contrast, it was significantly ameliorated, albeit not completely abolished, after BS. Finally, obese subjects had evidence of pulmonary inflammation (exhaled condensate) that also decreased after BS. Conclusions The systemic inflammome of morbid obesity is independent of sex, smoking status and/or comorbidities, it is significantly reduced by BS and mirrored in the lungs.

Accuracy of Vigileo/Flotrac monitoring system in morbidly obese patients

PURPOSE Our goal was to assess the accuracy of measuring cardiac output (CO) by the FloTrac/Vigileo (CO(V)) device in comparison with thermodilution technique through pulmonary artery catheterization (PAC(TD)) in morbidly obese patients. MATERIAL AND METHODS Cardiac output in 8 morbidly obese patients was assessed twice at upright and lying position breathing ambient air. At least 4 consecutive CO measurements with 10 mL of ice-cold saline injections were performed each time. Simultaneous CO measurements were recorded with both single-bolus thermodilution and CO(V). RESULTS One hundred thirty-two CO data pairs were collected. The overall mean single-bolus thermodilution 6.2 ± 1.1 L/min was lower than the overall mean CO(V) 7.8 ± 1.6 L/min (P < .001). Lin concordance coefficient indicated that overall agreement between PAC(TD) and CO(V) was poor, 0.29. Lin concordance coefficient in sitting position was 0.29, 95% confidence interval (0.17-0.40) and in lying position was 0.30, 95% confidence interval (0.15-0.44). The Bland-Altman plot analysis showed systematically higher values from CO(V) in comparison with PAC(TD). These differences increased in presence of high CO measurements. In 3 of 8 patients, the percentage error was lower than 20%, whereas in the other 5, it was higher than 20%. Of these 5, in 2 cases, the percentage error was greater than 50%. CONCLUSION Data obtained using CO(V) vs PAC(TD) measurements showed poor correlation. The results were not interchangeable.

Intraoperative Management of High-Risk Liver Transplant Recipients: Concerns and Challenges

Liver transplantation (LT) offers patients with liver disease a real chance for long-term survival. In the past decade, successful survival after LT along with the Model for End-Stage Liver Disease-based allocation policy have increased willingness to accept patients with a higher risk profile and marginal organs and to prioritize the sickest patients on the waiting list. Therefore, the anesthesiologist now deals with very challenging patients. In the present review, we aimed to highlight key aspects of intraoperative LT management in high-risk patients and to place these aspects in the perspective of their impact on perioperative outcomes. Conservative standardized perioperative strategies mandate a switch toward accurate and tailored perioperative anesthetic care to maintain the steady improvement in recipient survival rates after LT. In our opinion, continuous assessment of fluid status and cardiac performance, strategies promoting graft decongestion, rational hemostatic management, and the identification of LT recipients with potential risk of vascular complications should constitute the cornerstone of intraoperative management.

Can mean platelet volume be used as a biomarker of pathological fibrin clot strength related to obesity

• Dysfunctional adipose tissue induced platelet activation leading to hypercoagulability.

Can the Lung be Obese? The Effects of Bariatric Surgery on Lung Function and Imaging

Obesity is a state of low-grade chronic systemic inflammation that induces a reduction of adiponectin production with inhibition of the vasorelaxant properties of perivascular adipose tissue with underlying widespread endothelial dysfunction. This review concentrates on the main pulmonary and non-pulmonary determinants of gas exchange abnormalities, characterized by mild-to-moderate increased alveolar-arterial O2 difference, with or without mild hypoxaemia, in non-smoking morbidly obese subjects without associated relevant co-morbidities, candidates to bariatric surgery, induced by ventilation-perfusion imbalance and increased intrapulmonary shunt, including the effects of 100% oxygen breathing and those induced by postural changes. Likewise, we review lung imaging abnormalities, more specifically lung tissue volume, and their interaction with gas exchange disturbances. Finally, we address the long-term beneficial effects of bariatric surgery on all these obesity-induced lung function and imaging defects. Overall, we present a compelling evidence of lung function and imaging abnormalities underlying systemic and pulmonary inflammation in morbidly obese candidates to bariatric surgery. (BRN Rev. 2018;4:53-66) Corresponding author: Eva Rivas, erivas@clinic.cat; rivasfe@ccf.org