Machine learning for the localization of Subthalamic Nucleus during deep brain stimulation surgery: a systematic review and Meta-analysis.

INTRODUCTION: Delineating subthalamic nucleus (STN) boundaries using microelectrode recordings (MER) and trajectory history is a valuable resource for neurosurgeons, aiding in the accurate and efficient positioning of deep brain stimulation (DBS) electrodes within the STN. Here, we aimed to assess the application of artificial intelligence, specifically Hidden Markov Models (HMM), in the context of STN localization. METHODS: A comprehensive search strategy was employed, encompassing electronic databases, including PubMed, EuroPMC, and MEDLINE. This search strategy entailed a combination of controlled vocabulary (e.g., MeSH terms) and free-text keywords pertaining to "artificial intelligence," "machine learning," "deep learning," and "deep brain stimulation." Inclusion criteria were applied to studies reporting the utilization of HMM for predicting outcomes in DBS, based on structured patient-level health data, and published in the English language. RESULTS: This systematic review incorporated a total of 14 studies. Various machine learning compared wavelet feature to proposed features in diagnosing the STN, with the HMM yielding a diagnostic odds ratio (DOR) of 838.677 (95% CI: 203.309-3459.645). Similarly, the K-Nearest Neighbors (KNN) model produced parameter estimates, including a diagnostic odds ratio of 25.151 (95% CI: 12.270-51.555). Meanwhile, the support vector machine (SVM) model exhibited parameter estimates, with a DOR of 13.959 (95% CI: 10.436-18.671). CONCLUSIONS: MER data demonstrates significant variability in neural activity, with studies employing a wide range of methodologies. Machine learning plays a crucial role in aiding STN diagnosis, though its accuracy varies across different approaches.

Preoperative evaluation in thoracic surgery: limits of the patient's functional operability and consequence for perioperative anaesthesiologic management.

PURPOSE OF REVIEW: Preoperative evaluation of older and more morbid patients in thoracic surgery is getting more advanced. In this context, early risk stratification has a crucial role for adequate informed decision-making, and thus for generating favourable effects of clinical outcome. RECENT FINDINGS: Recent findings confirm that many risk factors impair mortality and morbidity beyond classical medical findings like results of lung function tests and values of the revised cardiac risk index. Especially results from holistic views on patients' functional status like frailty assessments are linked with long-term survival after lung resection. SUMMARY: A comprehensive risk stratification by anaesthesiologists generates valuable guidance for the best strategy of clinical treatment. This includes preoperative, peri-operative and postoperative interventions, provided by interdisciplinary healthcare providers, resulting in an Early Risk Stratification and Strategy ('ERSAS') pathway.

Periprocedural safety and outcome after pump implantation for intravenous treprostinil administration in patients with pulmonary arterial hypertension.

METHODS: In this retrospective observational study, we analyzed all patients with pulmonary arterial hypertension undergoing LenusPro® pump implantation between November 2013 and October 2019 at our center. Periprocedural safety was assessed by describing all complications that occurred within 28 days after surgery; complications that occurred later were described to assess long-term safety. Clinical outcomes were measured by comparison of clinical parameters and echocardiographic measurements of right ventricular function from baseline to 6-months-follow-up. RESULTS: Fifty-four patients underwent LenusPro® pump implantation for intravenous treprostinil treatment during the investigation period. Periprocedural complications occurred in 5 patients; the only anesthesia-related complication (right heart failure with recovery after prolonged intensive care and death in the further course) occurred in the only patient who underwent general anesthesia. All other patients underwent local anesthesia with or without short-acting (analgo-) sedation. Eighteen long-term complications occurred in 15 patients, most notably pump pocket or catheter related problems. Transplant-free survival rates at 1, 2, and 3 years were 77 %, 56 %, and 48 %, respectively. CONCLUSIONS: Subcutaneous pump implantation under local anesthesia and conscious analgosedation while avoiding intubation and mechanical ventilation is feasible in patients with advanced PAH. Controlled studies are needed to determine the safest anesthetic approach for this procedure. BACKGROUND/OBJECTIVES: Intravenous treprostinil treatment via a fully implantable pump is a treatment option for patients with advanced pulmonary arterial hypertension. However, there is no consensus on the preferred anesthetic approach for the implantation procedure. Primary objective was to assess periprocedural safety with particular attention to feasibility of local anesthesia and conscious analgosedation instead of general anesthesia. Long-term safety and clinical outcomes were secondary endpoints.

[Perioperative Anaesthetic Management of Patients after Heart and Lung Transplantation]. / Anästhesiologisches Management von herz- und lungentransplantierten Patienten.

The outcome after heart and lung transplantation has improved significantly. Consequently, many patients are admitted to the hospital for routine surgical interventions that are initially non-transplant-specific. Some disorders lead to hospital admissions that affect other organ systems due to late consequences of the underlying disease or can be seen as early and late complications of the transplantation itself. Many of these surgical interventions are certainly carried out in the responsible transplant centre. Some surgeries are also performed in hospitals that do not primarily transplant and do not regularly care for heart and lung transplant patients. In these situations, the understanding of the physiology of the transplanted heart and lung, the consequences of the underlying disease and the post-transplant treatment with its peculiarities and risks is paramount. The anaesthetic management of these patients requires preoperative risk stratification and perioperative anaesthetic planning, but also responsibility for a suitable post-operative monitoring. This review article deals with the special anaesthetic consideration in patients after heart and lung transplantation.

Influence of different electrode belt positions on electrical impedance tomography imaging of regional ventilation: a prospective observational study.

BACKGROUND: Electrical impedance tomography (EIT) is a non-invasive bedside tool which allows an individualized ventilator strategy by monitoring tidal ventilation and lung aeration. EIT can be performed at different cranio-caudal thoracic levels, but data are missing about the optimal belt position. The main goal of this prospective observational study was to evaluate the impact of different electrode layers on tidal impedance variation in relation to global volume changes in order to propose a proper belt position for EIT measurements. METHODS: EIT measurements were performed in 15 mechanically ventilated intensive care patients with the electrode belt at different thoracic layers (L1-L7). All respiratory and hemodynamic parameters were recorded. Blood gas analyses were obtained once at the beginning of EIT examination. Off-line tidal impedance variation/tidal volume (TV/VT) ratio was calculated, and specific patterns of impedance distribution due to automatic and user-defined adjustment of the colour scale for EIT images were identified. RESULTS: TV/VT ratio is the highest at L1. It decreases in caudal direction. At L5, the decrease of TV/VT ratio is significant. We could identify patterns of diaphragmatic interference with ventilation-related impedance changes, which owing to the automatically adjusted colour scales are not obvious in the regularly displayed EIT images. CONCLUSIONS: The clinical usability and plausibility of EIT measurements depend on proper belt position, proper impedance visualisation, correct analysis and data interpretation. When EIT is used to estimate global parameters like VT or changes in end-expiratory lung volume, the best electrode plane is between the 4th and 5th intercostal space. The specific colour coding occasionally suppresses user-relevant information, and manual rescaling of images is necessary to visualise this information.

May student examiners be reasonable substitute examiners for faculty in an undergraduate OSCE on medical emergencies?

OBJECTIVES: To compare the effect of student examiners (SE) to that of faculty examiners (FE) on examinee performance in an OSCE as well as on post-assessment evaluation in the area of emergency medicine management. METHODS: An OSCE test-format (seven stations: Advanced Cardiac Life Support (ACLS), Basic Life Support (BLS), Trauma-Management (TM), Pediatric-Emergencies (PE), Acute-Coronary-Syndrome (ACS), Airway-Management (AM), and Obstetrical-Emergencies (OE)) was administered to 207 medical students in their third year of training after they had received didactics in emergency medicine management. Participants were randomly assigned to one of the two simultaneously run tracks: either with SE (n = 110) or with FE (n = 98). Students were asked to rate each OSCE station and to provide their overall OSCE perception by means of a standardized questionnaire. The independent samples t-test was used and effect sizes were calculated (Cohens d). RESULTS: Students achieved significantly higher scores for the OSCE stations "TM", "AM", and "OE" as well as "overall OSCE score" in the SE track, whereas the station score for "PE" was significantly higher for students in the FE track. Mostly small effect sizes were reported. In the post-assessment evaluation portion of the study, students gave significant higher ratings for the ACS station and "overall OSCE evaluation" in the FE track; also with small effect sizes. CONCLUSION: It seems quite admissible and justified to encourage medical students to officiate as examiners in undergraduate emergency medicine OSCE formative testing, but not necessarily in summative assessment evaluations.

Differential cytotoxic properties of drugs used for intra-articular injection on human chondrocytes: an experimental in-vitro study.

BACKGROUND: Intra-articular injection of local anaesthetics, opioids and corticosteroids is frequently used to obtain perioperative analgesia following joint surgery. Although local anaesthetics were shown to induce chondrotoxicity, the safety profile regarding chondrotoxicity of other injected drugs is less clear. OBJECTIVE: Our objective was to investigate cytotoxicity of drugs used for intra-articular analgesia. DESIGN: An experimental in-vitro study. SETTING: Hannover Medical School, science laboratory, 2013. MATERIAL: Human cartilage cell line T/C 28-a2. INTERVENTION: Incubation of cells with different concentrations of bupivacaine, s-ketamine, morphine and dexamethasone for 1 h. MAIN OUTCOME MEASURES: Fraction of Annexin V positive and Annexin V and propidium iodide double positive cells after 1 h of incubation with tested drug measured by flow cytometry. RESULTS: Both morphine (0.1 to 10 µmol l) and dexamethasone (10 to 1000 µmol/l) failed to induce cytotoxicity after 1 h of exposure. The previously reported chondrotoxicity of bupivacaine (10 to 500 µmol l or 2.8 to 140 µg ml) was confirmed by a concentration-dependent increased staining with Annexin V and propidium iodide. Exposure to S-ketamine (10 to 500 µmol l) induced a significant late apoptotic and necrotic cell fraction at 10 µmol l or 2.4 µg ml. Concentrations of 100 and 500 µmol l induced a significant increase in early apoptotic cells. CONCLUSION: Morphine and dexamethasone showed no cytotoxic effects in our study and might thus be better alternatives to the clinically frequently applied bupivacaine. S-ketamine induced an intensive dose-dependent cytotoxic effect and should probably be avoided for intra-articular injection.

Bedside monitoring of ventilation distribution and alveolar inflammation in community-acquired pneumonia.

It is unclear whether bedside monitoring tools such as exhaled nitric oxide measurements (FENO) and electrical impedance tomography (EIT) could help guiding patient management in community-acquired pneumonia (CAP). We hypothesized that exhaled NO would be increased in CAP patients and could be used to assess resolution of inflammation in the course of CAP therapy. Feasibility of multiple-breath (mb) and single-breath (sb) approach has been investigated. EIT was compared with chest X-ray at admission and used to assess whether the inhomogeneous ventilation changes due to treatment. 24 CAP patients were enrolled. Measurements were accomplished at admission (T0: EIT + FENO), after 3 days (T1: FENO) and 5-6 days after admission (T2: EIT + FENO). We computed an EIT distribution index (DEIT), which reflects the uniformity of ventilation. FENO measurements showed a significant decrease in NO after the beginning of antibiotic therapy [p = 0.04 (sb); p = 0.003 (mb)]. Correlation between sb method and mb method was significant (p < 0.001, r = 0.70). EIT detects right-sided and left-sided ventilation disorders due to pneumonia in correspondence to chest X-ray (p < 0.01). EIT images at T2 showed a more homogeneous ventilation distribution in displayed EIT. FENO could be a prospective supplementary tool to describe local lung inflammation as individual trend parameter. EIT could be a suitable supplementary tool to monitor functional lung status in CAP.

Intraoperative Circulatory Support in Lung Transplantation: Current Trend and Its Evidence.

Lung transplantation has a high risk of haemodynamic complications in a highly vulnerable patient population. The effects on the cardiovascular system of the various underlying end-stage lung diseases also contribute to this risk. Following a literature review and based on our own experience, this review article summarises the current trends and their evidence for intraoperative circulatory support in lung transplantation. Identifiable and partly modifiable risk factors are mentioned and corresponding strategies for treatment are discussed. The approach of first identifying risk factors and then developing an adjusted strategy is presented as the ERSAS (early risk stratification and strategy) concept. Typical haemodynamic complications discussed here include right ventricular failure, diastolic dysfunction caused by left ventricular deconditioning, and reperfusion injury to the transplanted lung. Pre- and intra-operatively detectable risk factors for the occurrence of haemodynamic complications are rare, and the therapeutic strategies applied differ considerably between centres. However, all the mentioned risk factors and treatment strategies can be integrated into clinical treatment algorithms and can influence patient outcome in terms of both mortality and morbidity.

Functional residual capacity-guided alveolar recruitment strategy after endotracheal suctioning in cardiac surgery patients.

OBJECTIVE: To determine whether the results of functional residual capacity measurements after endotracheal suctioning could guide the decision to perform an alveolar recruitment maneuver and thus improve lung function. DESIGN: Prospective, randomized, controlled interventional study. SETTING: Intensive care unit of a university hospital. PATIENTS: Fifty-nine mechanically ventilated patients within 2 hrs after elective cardiac surgery without preexisting lung diseases. INTERVENTIONS: Patients received a standard suctioning procedure with disconnection of the ventilator (20 secs, 14 F catheter, 200 cm H2O negative pressure). Prospectively, patients were stratified into two groups by the postsuctioning functional residual capacity value (group A: functional residual capacity >94% of baseline; group B: functional residual capacity <94% of baseline). Both groups were randomized into either a recruitment maneuver (RM) group (positive end-expiratory pressure 15 cm H2O, peak inspiratory pressure 35-40 cm H2O for 30 secs, group RM) or a non-RM group, in which ventilation was resumed without an RM (group NRM), resulting in four groups. MEASUREMENTS AND MAIN RESULTS: Functional residual capacity and arterial blood gases were recorded for up to 1 hr. In addition, distribution of ventilation was measured by means of electrical impedance tomography. The RM had an impact on distribution of ventilation, functional residual capacity, and oxygenation in patients with a decrease of functional residual capacity after suctioning. In contrast, the RM showed no impact on these parameters in patients with no decrease of functional residual capacity after suctioning. CONCLUSIONS: By measurements of functional residual capacity after endotracheal suctioning, patients profiting from a consecutive recruitment maneuver could be identified. Guiding the recruitment strategy on changes of functional residual capacity may improve patient care.

Developing a minimally-invasive anaesthesiological approach to non-intubated uniportal video-assisted thoracoscopic surgery in minor and major thoracic surgery.

BACKGROUND: Non-intubated uniportal video-assisted thoracoscopic surgery (niVATS) is a novel approach to major and minor lung resection. It benefits from a holistic anesthesiological concept with adequate pain relief and sedation in a minimal-invasive setup allowing thoracic procedures under spontaneous breathing. At present no anesthesiological gold standard for niVATS exists. The primary aim of our retrospective observational study was to evaluate feasibility and safety of minimally invasive niVATS for both minor and major pulmonary resections at our institution. METHODS: All 88 consecutive patients scheduled for niVATS minor or major thoracic procedures were included into the study. Anaesthesia was performed according to a departmental niVATS algorithm including both regional anaesthesia and sedation. Patient characteristics and early outcome data including intraoperative and postoperative findings were compared between groups. Prediction scores for postoperative complications (LAS VEGAS, ARISCAT, ThRCRI) were calculated and compared. RESULTS: No early mortality and a low overall morbidity rate of 28.4% were encountered. Conversion to orotracheal intubation was required in 6.8% of all cases. Postoperative pulmonary complications occurred in 15.9% of total cases and were lower than predicted by both LAS VEGAS and ARISCAT respectively. Cardiac complications were found in 1.1% and lower than predicted by ThRCRI. A persistent air leak occurred in 11.4% of total cases and was significantly higher in major resection. Postoperative chest tube duration and hospital length of stay in the major resection group exceeded times reported by other groups. CONCLUSIONS: niVATS appears to be safe in both minor and major thoracic procedures. A minimally invasive anaesthesiological approach foregoing central iv lines, arterial blood pressure measurement and urinary catheterization is feasible. Our niVATS protocol appears to be a viable alternative for both minor and major thoracic procedures in selected patients.

Determination of optimal positive end-expiratory pressure based on respiratory compliance and electrical impedance tomography: a pilot clinical comparative trial.

There is no agreement on gold standard method for positive end-expiratory pressure (PEEP) titration. Electrical impedance tomography (EIT) may aid in finding the optimal PEEP level. In this pilot trial, we investigated potential differences in the suggested optimal PEEP (BestPEEP) as derived by respiratory compliance and EIT-derived parameters. We examined if compliance-derived PEEP differs with regard to the regional ventilation distribution in relation to atelectasis and hyperinflation. Measurements were performed during an incremental/decremental PEEP trial in 15 ventilated intensive care patients suffering from mild-to-moderate impairment of oxygenation due to sepsis, pneumonia, trauma and metabolic and ischemic disorders. Measurement agreement was analyzed using Bland-Altman plots. We observed a diversity of EIT-derived and compliance-based optimal PEEP in the evaluated patients. BestPEEPCompliance did not necessarily correspond to the BestPEEPODCL with the least regional overdistension and collapse. The collapsed area was significantly smaller when the overdistension/collapse index was used for PEEP definition (p=0.022). Our results showed a clinically relevant difference in the suggested optimal PEEP levels when using different parameters for PEEP titration. The compliance-derived PEEP level revealed a higher proportion of residual regional atelectasis as compared to EIT-based PEEP.

Assessment of regional lung recruitment and derecruitment during a PEEP trial based on electrical impedance tomography.

OBJECTIVE: To investigate whether electrical impedance tomography (EIT) is capable of monitoring regional lung recruitment and lung collapse during a positive end-expiratory pressure (PEEP) trial. DESIGN: Experimental animal study of acute lung injury. SUBJECT: Six pigs with saline-lavage-induced acute lung injury. INTERVENTIONS: An incremental and decremental PEEP trial at ten pressure levels was performed. Ventilatory, gas exchange, and hemodynamic parameters were automatically recorded. EIT and computed tomography (CT) scans of the same slice were simultaneously taken at each PEEP level. MEASUREMENTS AND RESULTS: A significant correlation between EIT and CT analyses of end-expiratory gas volumes (r=0.98 up to 0.99) and tidal volumes (r=0.55 up to r=0.88) could be demonstrated. Changes in global and regional tidal volumes and arterial oxygenation (PaO2/FiO2) demonstrated recruitment/derecruitment during the trial, but at different onsets. During the decremental trial, derecruitment first occurred in dependent lung areas. This was indicated by lowered regional tidal volumes measured in this area and by a decrease of PaO2/FiO2. At the same time, the global tidal volume still continued to increase, because the increase of ventilation of the non-dependent areas was higher than the loss in the dependent areas. This indicates that opposing regional changes might cancel each other out when combined in a global parameter. CONCLUSIONS: EIT is suitable for monitoring the dynamic effects of PEEP variations on the regional change of tidal volume. It is superior to global ventilation parameters in assessing the beginning of alveolar recruitment and lung collapse.

Influence of intraoperative positive end-expiratory pressure level on pulmonary complications in emergency major trauma surgery.

INTRODUCTION: Pulmonary complications have a major impact on the morbidity and mortality of critically ill patients with multiple trauma. Intraoperative protective ventilation with low tidal volume may prevent lung injury and infection, whereas the role of positive end-expiratory pressure (PEEP) levels is unclear. The aim of this study was to evaluate the influence of different intraoperative PEEP levels on incidence of pulmonary complications after emergency trauma surgery. MATERIAL AND METHODS: We retrospectively analysed data of multiple trauma patients who underwent emergency surgery within 24 h after injury in our level I trauma centre (n = 86). On the basis of their intraoperative PEEP level, patients were divided into a low PEEP group with a PEEP of < 8 mbar and a high PEEP group with a PEEP of 8 mbar or higher. RESULTS: Besides differences in body mass index and preoperative oxygenation, there were no differences in patients' baseline data. There was a significant difference between incidence of pneumonia within 7 days after trauma surgery, with an incidence 26.7% in the low PEEP group and 7.3% in the high PEEP group (p = 0.02). The low PEEP group had higher pulmonary infection scores at days 3 and 5 after surgery. Oxygenation was better in the higher PEEP group postoperatively. There was no difference with respect to the incidence of acute respiratory distress syndrome, the mortality up until hospital discharge or haemodynamic parameters between groups. CONCLUSIONS: Higher PEEP levels were associated with perioperative improvement of oxygenation and a lower incidence of pneumonia, without impairment of haemodynamics. Additional studies should be initiated to confirm these observations.

Can today's house officers teach effectively? An assessment in undergraduate emergency training.

BACKGROUND: Previous publications describe house officers (HOs) as unaware of their ineffective teaching skills. OBJECTIVE: The aim of this study was to evaluate the role of teaching seniority in the comparison of teaching skills between HOs and faculty. MATERIALS AND METHODS: Ten HOs (F: n=4, M: n=6, age: 35.1±6.8 years) and nine faculty (F: n=3, M: n=6, age: 41.4±4.9 years) who actively teach undergraduate emergency medicine were immediately evaluated at the end of the course by their students using the questionnaire SFDP26. The questionnaire consists of one item on 'overall teaching effectiveness' (OTE) (1=very poor to 5=excellent) and 25 items measured on a five-point Likert scale (1-5=strongly disagree to strongly agree) divided into seven subscales: 1, 'establishing the learning climate' (LC); 2, 'control of session' (CS); 3, 'communication of goals' (CG); 4, 'facilitating understanding and retention' (UR); 5, 'evaluation' (E); 6, 'feedback' (FB) and 7, 'promoting self-directed learning' (SL). The sample included 173 medical students in their third year of training who were randomly assigned to the instructors. A Mann-Whitney U-test was used to calculate group-related differences (resident vs. teaching faculty). For significant differences, effect size was calculated (r=Z/√N). RESULTS: No sex-related differences were found. Significantly better ratings for HOs were found in subscales: 1, 'LC' (P=0.001; r=0.20); 2, 'CS' (P=0.037; r=0.15); 5, 'E' (P=0.007; r=0.20); 6, 'FB' (P=0.001; r=0.23); 7, 'SL' (P=0.004; r=0.24) and 'OTE' (P=0.027; r=0.26). CONCLUSION: From a learner's perspective, the quality of teaching provided by HOs was rated at least similar and mostly better overall than that provided by faculty. These findings contradict results from previous studies on the quality of HO teaching and therefore warrant further assessment.

The suitability of EIT to estimate EELV in a clinical trial compared to oxygen wash-in/wash-out technique.

INTRODUCTION: Open endotracheal suctioning procedure (OSP) and recruitment manoeuvre (RM) are known to induce severe alterations of end-expiratory lung volume (EELV). We hypothesised that EIT lung volumes lack clinical validity. We studied the suitability of EIT to estimate EELV compared to oxygen wash-in/wash-out technique. METHODS: Fifty-four postoperative cardiac surgery patients were enrolled and received standardized ventilation and OSP. Patients were randomized into two groups receiving either RM after suctioning (group RM) or no RM (group NRM). Measurements were conducted at the following time points: Baseline (T1), after suctioning (T2), after RM or NRM (T3), and 15 and 30 min after T3 (T4 and T5). We measured EELV using the oxygen wash-in/wash-out technique (EELVO2) and computed EELV from EIT (EELVEIT) by the following formula: EELVEITTx,y…=EELVO2+ΔEELI×VT/ΔZ. EELVEIT values were compared with EELVO2 using Bland-Altman analysis and Pearson correlation. RESULTS: Limits of agreement ranged from -0.83 to 1.31 l. Pearson correlation revealed significant results. There was no significant impact of RM or NRM on EELVO2-EELVEIT relationship (p=0.21; p=0.23). DISCUSSION: During typical routine respiratory manoeuvres like endotracheal suctioning or alveolar recruitment, EELV cannot be estimated by EIT with reasonable accuracy.

Non-invasive cerebral oxygenation reflects mixed venous oxygen saturation during the varying haemodynamic conditions in patients undergoing transapical transcatheter aortic valve implantation.

Transapical transcatheter aortic valve implantation (TA-TAVI) is increasingly used to treat aortic valve stenosis in high-risk patients. Mixed venous oxygen saturation (SvO(2)) is still the 'gold standard' for the determination of the systemic oxygen delivery to consumption ratio in cardiac surgery patients. Recent data suggest that regional cerebral oxygen saturation (rScO(2)) determined by near-infrared spectroscopy is closely related to SvO(2). The present study compares rScO(2) and SvO(2) in patients undergoing TA-TAVI. n = 20 cardiac surgery patients scheduled for TA-TAVI were enrolled in this prospective observational study. SvO(2) and rScO(2) were determined at predefined time points during the procedure. Correlation and Bland-Altman analysis of the complete data set showed a correlation coefficient of r(2 )= 0.7 between rScO(2) and SvO(2) (P < 0.0001), a mean difference (bias) of 5.8 with limits of agreement (1.96 SD) of -6.8 to 18.3% and a percentage error of 17.5%. At all predefined time points correlation was moderate (r(2 )= 0.50) to close (r = 0.84), and the percentage error was <24%. RScO(2) determined by near-infrared spectroscopy is correlated to SvO(2) during varying haemodynamic conditions in patients undergoing TA-TAVI. This suggests that rScO(2) is reflective not only of the cerebral, but also of the systemic oxygen balance.

Low preoperative cerebral oxygen saturation is associated with longer time to extubation during fast-track cardiac anaesthesia.

OBJECTIVES: Fast-track cardiac anaesthesia programs aiming at early tracheal extubation have not only been linked to a decrease in intensive care unit and hospital length of stay but also to a decrease in morbidity and mortality as well as a containment of rising medical costs. General recommendations for the inclusion criteria concerning fast-track programs are not available. METHODS: The present study determined the factors influencing the time to extubation in patients undergoing a newly implemented fast-track protocol. Seventy-nine patients were retrospectively studied. Successful fast track was defined as time to extubation within 75 min after admission to ICU. RESULTS: Sixty patients fulfilled the successful fast-track criteria with a mean time to extubation of 43.9 min (range 15-75 min). Nineteen patients needed more than 75 min to be weaned from the respirator with a mean time to extubation of 135 min (range 90-320 min). Analysis of pre- and intraoperative factors revealed that these groups differed only with respect to preoperative cerebral oxygen saturation levels: 67.7 ± 5.2 versus 60.8 ± 7.4%. CONCLUSIONS: Cerebral oxygen saturation assessment prior to cardiac surgery is significantly related to time to extubation and may thus be used to stratify candidates in fast-track programs.