Echocardiographic right ventricular evaluation in cardiac surgery patients undergoing mitral valve reconstruction: a single center prospective observational study.

Background: Mitral valve (MV) regurgitation (MR) is the second most frequent indication for valvular surgery in Europe. Right ventricular (RV) dysfunction is a common finding after cardiac surgery and might persist for years. The RV-function after MV surgery has been controversially discussed. We therefore aimed to evaluate early RV-performance in patients undergoing MV surgery. Methods: Between 09/2020 and 06/2022, ninety-two patients presenting with MR undergoing MV surgery were consented and prospectively included for evaluation. Echocardiographic evaluation was performed one day before surgery, one week after surgery and three months later. Primary endpoints reported RV-function changes including tricuspid annular plane systolic excursion (TAPSE), RV systolic prime (S') and fractional area change (FAC). Secondary endpoints included stability of MV repair, changes in left ventricular functions and early mortality. Results: Mean patients' age was 59.1±11.4 years. Fifty-five (59.7%) patients were male. Most of patients presented with severe (n=88; 95.7%) MR. Mean systolic pulmonary artery pressure was 35.6±15.7 mmHg. Moderate or severe pulmonary arterial hypertension (PAH) was present in 60 (65.2%) patients. Patients underwent either isolated MV surgery (n=67; 72.8%) or combined with tricuspid valve surgery (n=25; 27.2%). Minimal invasive surgery was performed in 26.1% (n=24) of the patients. Postoperative short-term follow-up at 3 months reported RV-dysfunction in 44.5% (n=41) of the patients as indicated by reductions in TAPSE & RV S' from 21.2±4.7 to 14±3.3 mm (P<0.001) and from 14.7±4.3 to 9.7±2.8 cm/s (P<0.001) respectively. The FAC reduction from 42.9%±9.6% to 42.2%±9.9% was non-significant (P=0.593) and no need for redo mitral or tricuspid valve surgery was reported. Finally, the presence and severity of preoperative PAH played significant roles for the incidence of RV dysfunction, P=0.021 and P=0.047, respectively. Minimal invasive surgical procedure significantly reduced the incidence of postoperative RV-dysfunction (P=0.013). Conclusions: Study early results report a significant reduction of RV-function after MV surgery as measured by TAPSE, & RV S', even when the FAC remains unchanged. Even though, this finding has limited prognostic implications during an uneventful surgical course.

The Feeling of Time Passing Is Associated with Recurrent Sustained Activity and Theta Rhythms Across the Cortex.

Introduction: We are constantly estimating how much time has passed, and yet know little about the brain mechanisms through which this process occurs. In this pilot study, we evaluated so-called subjective time estimation with the temporal bisection task, while recording brain activity from electroencephalography (EEG). Methods: Nine adult participants were trained to distinguish between two durations of visual stimuli as either "short" (400 msec) or "long" (1600 msec). They were then presented with stimulus durations in between the long and short stimuli. EEG data from 128 electrodes were examined with a novel analytical method that identifies segments of sustained cortical activity during the task. Results: Participants tended to categorize intermediate durations as "long" more frequently than "short" and were thus experiencing time as moving faster while overestimating the amount of time passing. Their mean bisection point (during which frequency of selecting short vs. long is equal) was closer to the geometric mean of task stimuli (800 msec) rather than the arithmetic mean (1000 msec). In contrast, sustained brain activity occurred closer to the arithmetic mean. The recurrence rate of this activity was highly related to the bisection point, especially when analyzed within naturally occurring theta oscillations (4-8 Hz) (r = -0.90). Discussion: Sustained activity across the cortex within the theta range may reflect temporal durations, whereas its repeated appearance relates to the subjective feeling of time passing.

Virtual reality-assisted distraction during transcatheter aortic valve implantation under local anaesthesia: A randomised study.

BACKGROUND: A minimal approach, using local anaesthesia alone, has been advocated to promote faster transcatheter aortic valve replacement (TAVR) procedures in intermediate-risk patients. Pre- and periprocedural anxiety and pain remain a concern. Virtual reality (VR) is a form of non-pharmacological distraction that can potentially modulate pain and anxiety. This randomised study explored whether VR reduces pain and anxiety during TAVR without sedation and compared the effects of VR with those of standard care. METHODS AND RESULTS: Between June 2022 and March 2023, 207 patients underwent transfemoral TAVR (TF-TAVR). Of these, 117 (56.5%) patients were willing to participate in the study and met the educational background and mental status criteria for assessment. Fifty-nine patients underwent TF-TAVR with VR glasses (VR group). Fifty-eight patients underwent standard TF-TAVR without VR (control group; CG). Post-interventional anxiety scores (STAI-S) (31.5 ± 13.4 vs. 38.5 ± 19.2, p = 0.02) and the perceived duration of the procedure (60.1 ± 32.3 vs. 73.0 ± 32.4, p = 0.04) were lower in the VR than in the CG. Procedure time, pain, and anxiety scores (visual analogue scale) were similar between the groups. The complication rate was low and not associated with VR. Post-interventional delirium occurred in nine patients, and was similar between the groups (VR: 4 [6.8%] vs. CG: 5 [8.6%], p = 0.71). No periprocedural strokes were observed. CONCLUSION: VR for TAVR is feasible and safe and expands the non-drug spectrum of therapy for anxiety and pain in patients undergoing TAVR with a minimalistic approach.

Role of Antiplatelet Therapy in Patients with Severe Coronary Artery Disease Undergoing Coronary Artery Endarterectomy within Coronary Artery Bypass Surgery.

Background-Coronary endarterectomy (CEA) has been introduced to allow revascularization in end-stage coronary artery disease (CAD). After CEA, the injured remnants of the vessel's media could result in fast neo intimal tissue ingrowth, which require an anti-proliferation agent (antiplatelet therapy (APT). We aimed to review outcomes of patients undergoing CEA within bypass surgery who received either single-APT (SAPT) or dual-APT (DAPT). Methods-We retrospectively evaluated 353 consecutive patients undergoing CEA within isolated coronary artery bypass grafting (CABG) in the period 01/2000-07/2019. After surgery, patients received either SAPT (n = 153), or DAPT (n = 200) for six months then lifelong SAPT. Endpoints included early, late survival, and freedom from major-adverse-cardiac and cerebrovascular events (MACCE), which were defined as incidence of stroke, myocardial infarction, need for coronary intervention (PCI or CABG) or death for any cause. Results-Patients' mean age was 67 ± 9.3 years; they were predominantly male 88.1%. Both DAPT- and SAPT-groups had the same extent of CAD (mean SYNTAX-Score-II: 34.1 ± 11.6 vs. 34.4 ± 17.2, p = 0.91). Postoperatively, no difference between DAPT- and SAPT-groups was reported in the incidence of low-cardiac-output syndrome (5% vs. 9.8%, p = 0.16), revision for bleeding (5% vs. 6.5% p = 0.64), 30-day mortality (4.5% vs. 5.2%, p = 0.8) or MACCE (7.5% vs. 11.8%, p = 0.19). Imaging follow-up reported significantly higher CEA and total grafts patency (90% vs. 81.5% and 95% vs. 81%, p = 0.017) in DAPT patients. Late outcomes within 97.4 ± 67.4 months show lower incidence of overall mortality (19 vs. 51%, p < 0.001) and MACCE (24.5 vs. 58.2%, p < 0.001) in the DAPT patients when compared with SAPT patients. Conclusions-Coronary endarterectomy allows revascularization in end-stage CAD when the myocardium is still viable. The use of dual APT after CEA for at least six months seems to improve mid-to-long-term patency rates and survival, and reduced the incidence of major adverse cardiac and cerebrovascular events.

Outcomes of Patients Undergoing Closed Traction CoronaryEndarterectomy: A Long-Term Single Center Study.

Background-Coronary endarterectomy (CEA) is an option for treating severely diffused coronary artery diseases; however, many surgeons avoid performing it due to its complexity and reported controversial results. Therefore, we aimed to review the results of patients undergoing CEA within coronary artery bypass grafting (CABG). Methods-This is a retrospective observational study evaluating the results of patients undergoing CEA within CABG surgery between March 2003 and February 2018. Follow-up via active personal and/or telephone interviews was performed to evaluate long-term clinical outcomes. The study endpoints included early postoperative incidence of myocardial infarction or cardiac mortality, long-term survival, and freedom from major adverse cardiac and cerebrovascular events (MACCE). Results-A total of 326 patients were included in this study for evaluation. The patients' mean age was 67 years; 88% were male, and most presented with three-vessel disease, reporting a mean SYNTAX score of 33.1 ± 12. Approximately 5.5% (n = 18) of the patients had undergone previous CABG surgery. A total of 394 CEAs within a mean of 4.3 ± 1.1 grafts per patient were performed. The indication for CEA was either totally (n = 111, 28.2%) or sub-totally (n = 283, 71.8%) occluded coronary arteries. Early results included perioperative myocardial infarction in eight (2.4%), stroke in eight (2.4%), and in-hospital mortality in thirteen (4.0%) patients. Long-term clinical follow-up reported mortality in 27.6% and overall incidence of MACCE in 41.4% of the patients at the ten-year follow-up. Conclusions-Patients with severe and diffuse CAD are difficult candidates for surgical revascularization. CEA offers an option to allow complete revascularization, even in the case of chronic occlusion, when the myocardium is still viable. The closed traction CEA technique presented here is our preferred method; it achieves satisfactory short- and long-term results.

Does the clinical experience of a tutor influence how students learn extended focused assessment with sonography for trauma: A randomized controlled trial.

BACKGROUND: Extended focused assessment with sonography for trauma (eFAST) is now an essential part of the primary survey of an emergency patient. The discrepancy between an increasing number of medical students and growing clinical commitments of lecturers is a major challenge in student teaching that needs to be resolved. The practice of using peers in the clinical education of medical students is a well-established tradition and commonly practiced but lacks definition in its implementation. Therefore, we aimed to investigate whether the level of experience of the tutor affects the effectiveness of learning among students using eFAST during a clinical scenario. METHODS: A prospective randomized single-blinded controlled trial, where 168 medical students in the eighth semester were randomized into control and intervention groups. The control group received the 4-h standard ultrasound (US) tutorial from various resident doctors. All residents were at least stage-1-certified in ultrasound. The intervention group received the tutorial from trained peer teachers (TPTs). These TPTs were medical students who were qualified to teach the procedure. All students received an initial tutorial on basic ultrasound principles and a final lecture on recognizing pathological images. Students completed basic questionnaires requesting pre-existing US experience, theoretical and clinical application questions based on eFAST one day later and at the end of the semester. Students also completed a 6-min OSCE (Objective-Structured-Clinical-Exam) station involving clinical emergency scenarios. RESULTS: Eighty-five percent of participants had no previous eFAST experience. Early and later evaluation of the participants show no significant differences between both groups regarding the theoretical and the clinical application examinations, except the early phase OSCE results, which was not repeated in the late-stage results. CONCLUSIONS: Peer-teaching can be utilized to teach practical skills such as eFAST without a loss of clinical application skills. This relieves the burden of removing doctors from patient care situations and maintains teaching standards.

Anesthetic Management during Robotic-Assisted Minimal Invasive Thymectomy Using the Da Vinci System: A Single Center Experience.

Background: Robotic-assisted surgery is gaining more adaption in different surgical specialties. The number of patients undergoing robotic-assisted thymectomy is continuously increasing. Such procedures are accompanied by new challenges for anesthesiologists. We are presenting our primary anesthesiologic experience in such patients. Methods: This is a retrospective single center study, evaluating 28 patients who presented with thymoma or myasthenia gravis (MG) and undergone minimal invasive robotic-assisted thoracic thymectomy between 01/2020−01/2022. We present our fast-track anesthesia management as a component of the enhanced recovery program and its primary results. Results: Mean patient's age was 46.8 ± 18.1 years, and the mean height was 173.1 ± 9.3 cm. Two-thirds of patients were female (n = 18, 64.3%). The preoperative mean forced expiratory volume in the first second (FEV1) was 3.8 ± 0.7 L, forced vital capacity (FVC) was 4.7 ± 1.1 L, and the FEV1/FVC ratio was 80.4 ± 5.3%. After the creation of capnomediastinum, central venous pressure and airway pressure have been significantly increased from the baseline values (16.5 ± 4.9 mmHg versus 13.4 ± 5.1 mmHg, p < 0.001 and 23.4 ± 4.4 cmH2O versus 19.3 ± 3.9 cmH2O, p < 0.001, respectively). Most patients (n = 21, 75%) developed transient arrhythmias episodes with hypotension. All patients were extubated at the end of surgery and discharged awake to the recovery room. The first 16 (57.1%) patients were admitted to the intensive care unit and the last 12 patients were only observed in intermediate care. Postoperatively, one patient developed atelectasis and was treated with non-invasive ventilation therapy. Pneumonia or reintubation was not observed. Finally, no significant difference was observed between MG and thymoma patients regarding analgesics consumption or incidence of complications. Conclusions: Robotic-assisted surgery is a rapidly growing technology with increased adoption in different specialties. Fast-track anesthesia is an important factor in an enhanced recovery program and the anesthetist should be familiar with challenges in this kind of operation to achieve optimal results. So far, our anesthetic management of patients undergoing robotic-assisted thymectomy reports safe and feasible procedures.

Impact of Non-Valvular Non-Coronary Concomitant Procedures on Outcomes of Surgical Aortic Valve Replacement in Intermediate Risk Patients.

INTRODUCTION: advanced age and concomitant procedures could increase the risk of perioperative complications during surgical aortic valve replacement (SAVR). We aimed to evaluate results of elderly patients undergoing SAVR and evaluate the impact of concomitant non-valvular, non-coronary procedures on the outcomes. METHODS: A retrospective single-centre study, evaluating 464 elderly patients (mean age = 75.6 ± 4 years) undergoing either isolated-SAVR (I-SAVR = 211) or combined-SAVR (C-SAVR = 253) between 01/2007 and 12/2017. Combined-SAVR involved non-valvular, non-coronary procedures. Study endpoints are postoperative results concerning the VARC-II criteria, valve dysfunction, long-term freedom from redo-AVR and survival. RESULTS: males were 52.8%. Patients had an intermediate risk profile (mean EuroSCORE-II (%) 5.2 ± 5). Postoperative results reported no significant differences in incidence of re-exploration for bleeding (6.6% vs. 6.7%, p = 1.0), stroke (0.9% vs. 0.4%, p = 0.59), dialysis (6.2% vs. 9.5%, p = 0.23) and pacemaker implantation (3.3% vs. 2.8%, p = 0.79) between I-SAVR and C-SAVR groups. Thirty-day (2.4% vs. 7.1% p = 0.03), one-year (5.7% vs. 13.8%, p = 0.003) and overall mortality (24.6% vs. 37.5%, p = 0.002) were lower in the isolated-SAVR group. Re-AVR was indicated in 1.7% of patients due to endocarditis. CONCLUSIONS: SAVR in elderly patients offers good outcomes with increased life quality and rare re-operation for structural valvular deterioration. Mortality rates were significantly higher when SAVR was combined with another "non-valvular, non-coronary" procedure.

Fast-track anesthesia in lateral mini-thoracotomy for transapical transcatheter valve implantation.

BACKGROUND: Patients who undergo transapical transcatheter aortic/mitral valve implantation are at higher risk of morbidity and mortality than those undergoing transvascular procedures. In addition, these patients have prolonged intensive care and hospital courses. Fast-track anesthesia could reduce perioperative complications and admission stays in such patients. METHODS: This retrospective single-center study, evaluates six high-risk patients undergoing transapical valve implantation between 01/2020 till 01/2021. All patients received a paravertebral block (PVB) as part of a fast-track approach. The airway was secured with a Gastro-double-lumen laryngeal mask which includes one orifice was for ventilation and one for the transesophageal echocardiography probe. Anesthesia was maintained with a volatile anesthetic (Sevoflurane MAC 1%). Immediately post procedure, all patients were awakened and admitted to the intermediate/intensive-care unit. RESULTS: Three patients were females, mean age =71±6 years, patients' risk profiles were high (mean Log. EuroSCORE-I 22% & STS-PROM 10%). No incidents of re-intubation, atelectasis/pneumonia, low output syndrome, stroke, dialysis, pacemaker implantation or operative mortality were reported. One patient (16.7%) underwent re-exploration for bleeding and developed a wound infection. Postoperative pain scores showed that no patient required additional analgesics after the initial eight hours post procedure. Mean postoperative intermediate/intensive-care stay was 13.8±3.2 hours and patients were mobilized early and discharged to the normal ward. CONCLUSIONS: Fast-track anesthesia using paravertebral-blockade for transcatheter transapical valve replacement in high-risk patients is a possible anesthetic approach. An effective PVB, in addition to a double-lumen laryngeal mask, provide an alternative strategy to conventional general anesthesia. These promising results could encourage further consideration of this approach in similar cardiac surgery patients.

Stereotactic Radiofrequency Thalamotomy for Cancer Pain: A Systematic Review.

Pain is a common occurrence in patients with cancer, which, in some cases, is not adequately controlled with medical analgesia. Thalamotomy is a treatment option in such circumstances, but synthesis of historical evidence and thalamic stratified data are lacking. We therefore sought to systematically review evidence supporting radiofrequency thalamotomy for intractable cancer pain. This review was performed using multiple electronic databases and a (PICO) patient/problem, intervention, comparison, outcome search with the terms "radiofrequency thalamotomy" and "cancer pain." Of 22 full-text studies assessed for eligibility, 14 were included for review. Articles were excluded in which radiofrequency ablation was not used, chronic implantation was used, or the study did not include patients with cancer pain. Thirteen case series and 1 case report were included. Thalamic targets included ventral posterior, central lateral, dorsomedial, centromedian, centromedian/parafascicular, centromedian and anterior pulvinar, pulvinar, limitans, suprageniculate and posterior nuclei. Patient characteristics, operative methods, lesioning parameters, patient follow-up, and outcomes were variably reported across the studies. Where relevant outcome data were available, 97% of patients experienced initial pain relief and 79% experienced significant lasting relief. Adverse events were typically transient. We conclude that radiofrequency thalamotomy for cancer pain is well tolerated and can produce significant relief from intractable cancer pain. No superiority of thalamic target could be determined.

Pooled Specimen Testing Using Automated Cartridge-Based System for COVID-19: The Cost on Sensitivity.

BACKGROUND: Pooled specimen screening for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can improve laboratory testing capacity. This study assessed the impact of pooling and retesting individual swabs on the overall detection rate and reduction in the frequency of retesting. METHODS: One hundred respiratory swabs specimens were tested individually and in pools of three or five samples using the Cepheid's Xpert® Xpress SARS-CoV-2 test kit. The optimum number of samples per pool was calculated using the application 'A Shiny App for Pooled Testing'. RESULTS: Twenty-five pools were generated from 101 samples. Out of 13 pools that contained five samples each, three pools gave true positive results. While out of the 12 pools that contained three samples each, five pools gave true positive results. Four samples gave a false negative pool result. The overall sensitivity and specificity of the assay in the pools were 66.6% and 100%, respectively. The cycle threshold was reduced in most of the pools compared to individual sample tests. CONCLUSION: The overall pooled test had a remarkable impact on laboratory resources. Yet, caution is warranted when selecting the cases for pooled testing, since the reduction in sensitivity can significantly impact and increase the risk of exposure to infection.

Early classification of motor tasks using dynamic functional connectivity graphs from EEG.

Objective. Classification of electroencephalography (EEG) signals with high accuracy using short recording intervals has been a challenging problem in developing brain computer interfaces (BCIs). This paper presents a novel feature extraction method for EEG recordings to tackle this problem.Approach. The proposed approach is based on the concept that the brain functions in a dynamic manner, and utilizes dynamic functional connectivity graphs. The EEG data is first segmented into intervals during which functional networks sustain their connectivity. Functional connectivity networks for each identified segment are then localized, and graphs are constructed, which will be used as features. To take advantage of the dynamic nature of the generated graphs, a long short term memory classifier is employed for classification.Main results. Features extracted from various durations of post-stimulus EEG data associated with motor execution and imagery tasks are used to test the performance of the classifier. Results show an average accuracy of 85.32% about only 500 ms after stimulus presentation.Significance. Our results demonstrate, for the first time, that using the proposed feature extraction method, it is possible to classify motor tasks from EEG recordings using a short interval of the data in the order of hundreds of milliseconds (e.g. 500 ms). This duration is considerably shorter than what has been reported before. These results will have significant implications for improving the effectiveness and the speed of BCIs, particularly for those used in assistive technologies.

Recognizing Pain in Motor Imagery EEG Recordings Using Dynamic Functional Connectivity Graphs.

The goal of this paper is to investigate whether motor imagery tasks, performed under pain-free versus pain conditions, can be discriminated from electroencephalography (EEG) recordings. Four motor imagery classes of right hand, left hand, foot, and tongue are considered. A functional connectivity-based feature extraction approach along with a long short-term memory (LSTM) classifier are employed for classifying pain-free versus under-pain classes. Moreover, classification is performed in different frequency bands to study the significance of each band in differentiating motor imagery data associated with pain-free and under-pain states. When considering all frequency bands, the average classification accuracy is in the range of 77:86-80:04%. Our frequency-specific analysis shows that the gamma band results in a notably higher accuracy than other bands, indicating the importance of this band in discriminating pain/no-pain conditions during the execution of motor imagery tasks. In contrast, functional connectivity graphs extracted from delta and theta bands do not seem to provide discriminatory information between pain-free and under-pain conditions. This is the first study demonstrating that motor imagery tasks executed under pain and without pain conditions can be discriminated from EEG recordings. Our findings can provide new insights for developing effective brain computer interface-based assistive technologies for patients who are in real need of them.

Classification of EEG Data Based on the Spatio-Temporo-Rhythmic Characteristics of the Task-Discriminating Functional Sub-networks.

We propose a new approach that utilizes the dynamic state of cortical functional connectivity for the classification of task-based electroencephalographic (EEG) data. We introduce a novel feature extraction framework that locates functional networks in the cortex as they convene at different time intervals across different frequency bands. The framework starts by applying the wavelet transform to isolate, then augment, EEG frequency bands. Next, the time intervals of stationary functional states, within the augmented data, are identified using the source-informed segmentation algorithm. Functional networks are localized in the brain, during each segment, using a singular value decomposition-based approach. For feature selection, we propose a discriminative-associative algorithm, and use it to find the sub-networks showing the highest recurrence rate differences across the target tasks. The sequences of augmented functional networks are projected onto the identified sub-networks, for the final sequences of features. A dynamic recurrent neural network classifier is then used for classification. The proposed approach is applied to experimental EEG data to classify motor execution and motor imagery tasks. Our results show that an accuracy of 90% can be achieved within the first 500 msec of the cued task-planning phase.

Stereotactic radiofrequency ventral posterolateral thalamotomy for cancer pain.

Palliative neuroablative procedures are often performed for medication-refractory cancer pain. A 57-year-old female with lung carcinoma and metastases to the brachial plexus and cervical spine with severe neuropathic pain affecting the right upper limb was referred to the authors' functional neurosurgery service. This video shows her treatment with an awake stereotactic radiofrequency thalamotomy targeting the left ventral posterolateral nucleus. Postoperatively, she experienced immediate and complete resolution of the pain. Palliative radiofrequency thalamotomy can be a viable and effective procedure for somatotopically distributed regional cancer pain. The video can be found here: https://youtu.be/jykYWXTP3c4.

Deep Brain Stimulation for Recovery of Consciousness in Minimally Conscious Patients After Traumatic Brain Injury: A Systematic Review.

OBJECTIVES: Minimally conscious state (MCS) is a disorder of consciousness in which minimal but definite behavioral evidence of self-awareness or environmental awareness is demonstrated. Deep brain stimulation (DBS) of various targets has been used to promote recovery in patients with disorders of consciousness with varying results. The aim of this systematic review was to assess the effects of DBS in MCS following traumatic brain injury (TBI). MATERIALS AND METHODS: A systematic literature review was carried out using a number of electronic bibliographic data bases to identify relevant studies. We included all studies describing applications of DBS on patients in MCS following TBI. RESULTS: Eight studies were identified, including a total of ten patients, aged 15-58 years. The time from injury to stimulation ranged from 3 to 252 months, with the duration of follow-up post-DBS ranging from 10 to 120 months. Seven patients improved their postsurgical outcome score measures (three patients with the coma recovery scale, one with the near coma scale, and three with the Glasgow outcome score). A descriptive favorable outcome was reported in one patient. Two patients were reported not to have shown any improvements following the intervention. CONCLUSIONS: Current evidence is based on a small population of heterogeneous patients. The time from injury to stimulation was significantly variable and problematic, as spontaneous recovery can occur within the first year of injury. Although seven patients showed promising results in validated outcome measures, evidence supporting the use of DBS in MCS patients following TBI is lacking. There is need for controlled and randomized studies.

Validation of a photoplethysmography device for detection of obstructive sleep apnea in the perioperative setting.

Obstructive sleep apnea (OSA) is a risk factor for perioperative complications, but many OSA patients present undiagnosed. While polysomnography (PSG) is the "gold standard" for diagnosis, its application is technology-intense, time-consuming, expensive, and requires specialists, often delaying surgery. Thus, miniaturized devices were developed for OSA screening aimed at ruling out major OSA while measuring a lesser number of biological signals. We evaluated the accuracy of a photoplethysmography (PPG)-based device for OSA detection. 48 patients with established or strongly suspected (STOP-Questionnaire) OSA scheduled for surgery underwent in their preoperative nights parallel recordings by PPG and a classic polygraphy (PG) devices (SomnoLab2®). We compared the diagnostic accuracy of the PPG in diagnosing mild [Apnea-/Hypopnea-Index (AHI) 5-14 events/h] and moderate-to-severe OSA (AHI > 15). PPG and PG-derived AHI correlated significantly (r = 0.85, p < 0.0001) and high area under curve (AUC) in receiver operator characteristics (ROC) values were seen for both AHI thresholds (0.93 and 0.95, respectively). For an AHI > 5, sensitivity was 100%, specificity 44%, positive predictive value (PPV) 62%, negative predictive value (NPV) 100%, likelihood ratio (LHR) 1.79, and Cohen κ was 0.43. For an AHI > 15, sensitivity was 92%, specificity 77%, PPV 60%, NPV 96%, LHR 4.04, and Cohen κ was 0.59. In a typical perioperative cohort of confirmed and suspected OSA patients, PPG reliably detected OSA patients while showing some false-positive results. Such devices are helpful for preoperative OSA screening.

Source-Informed Segmentation: A Data-Driven Approach for the Temporal Segmentation of EEG.

GOAL: Understanding the dynamics of brain function through non-invasive monitoring techniques requires the development of computational methods that can deal with the non-stationary properties of recorded activities. As a solution to this problem, a new data-driven segmentation method for recordings obtained through electroencephalography (EEG) is presented. METHODS: The proposed method utilizes singular value decomposition (SVD) to identify the time intervals in the EEG recordings during which the spatial distribution of clusters of active cortical neurons remains quasi-stationary. Theoretical analysis shows that the spatial locality features of these clusters can be, asymptotically, captured by the most significant left singular subspace of the EEG data. A reference/sliding window approach is employed to dynamically extract this feature subspace, and the running projection error is monitored for significant changes using Kolmogorov-Smirnov test. RESULTS: Simulation results, for a wide range of possible scenarios regarding the spatial distribution of active cortical neurons, show that the algorithm is successful in accurately detecting the segmental structure of the simulated EEG data. The algorithm is also applied to experimental EEG recordings of a modified visual oddball task. Results identify a unique sequence of dynamic patterns in the event-related potential (ERP) response to each of the three involved stimuli. CONCLUSION: The proposed method, without using source localization methods or scalp topographical maps, is able to identify intervals of quasi-stationarity in the EEG recordings. SIGNIFICANCE: The proposed segmentation technique can offer new insights on the dynamics of functional organization of the brain in action.

On the Spatiotemporal Characteristics of Class-Discriminating Functional Networks.

We target the problem of identifying brain's functional networks that are discriminatory across classes of tasks, using data obtained through electroencephalography (EEG). A three-step framework is presented. First, the EEG data is segmented to identify the intervals during which cortical functional networks remain quasi-stationary. Second, these functional networks are spatially localized in the cortex. Finally, by employing the proposed discriminative Boolean matrix factorization (DBMF) algorithm, functional networks that are most recurrent in one class of tasks, but are least recurrent in the other are identified. The DBMF algorithm is capable of providing the spatial maps of the discriminative functional networks as well as information about their dynamic occurrence over time. The framework is applied to experimental EEG data, recorded during a motor task. The results show that the proposed framework identifies several parietal/motor functional networks as being the most discriminatory for motor execution trials from non-execution trials.

Perioperative incidence of airway obstructive and hypoxemic events in patients with confirmed or suspected sleep apnea - a prospective, randomized pilot study comparing propofol/remifentanil and sevoflurane/remifentanil anesthesia.

BACKGROUND: Obstructive sleep apnea (OSA) is a risk factor for perioperative complications but data on anesthesia regimen are scarce. METHODS: In patients with established or strongly suspected OSA, we assessed in a prospective, randomized design the effects on nocturnal apnea-hypopnea-index (AHI) and oxygen saturation (SpO2) of propofol/remifentanil or sevoflurane/remifentanil based anesthesia. Patients were selected by a history for OSA and / or a positive STOP - questionnaire and received general anesthesia using remifentanil (12 µg/kg/h) combined either with propofol (4-6 mg/kg/h, n = 27) or sevoflurane (approx. 2.2 vol% endtidal, n = 27). AHI and SpO2 were measured during the nights before and after anesthesia. RESULTS: There were no differences in AHI between anesthetic regimens nor between the pre- and postoperative nights (propofol: 8.6 h- 1 (median, CI: 3.6-21.9) vs. 7.9 h- 1 (1.8-28.8); p = 0.97; sevoflurane: 3.8 h- 1 (1.8-7.3) vs. 2.9 h- 1 (1.2-9.5); p = 0.85). Postoperative minimum SpO2 (propofol: 80.7% ± 4.6, sevoflurane: 81.6 ± 4.6) did not differ from their respective preoperative baselines (propofol: 79.6% ± 6.5; p = 0.26, sevoflurane: 80.8% ± 5.2; p = 0.39). Even in patients with a preanesthetic AHI > 15, nocturnal AHI remained unchanged postoperatively. CONCLUSION: Thus, in a cohort of patients with suspected or confirmed OSA undergoing surgery of moderate duration and severity neither the volatile agent sevoflurane nor the intravenous anesthetic propofol altered nocturnal AHI or oxygen saturation, when combined with the short acting opioid remifentanil. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00005824 retrospectively registered on 03/12/2014.