[Machine learning in anesthesiology]. / "Machine learning" in der Anästhesiologie.

The application of artificial intelligence (AI) is currently changing very different areas of life. Artificial intelligence involves the emulation of human behavior with the aid of methods from mathematics and informatics. Machine learning (ML) represents a subdivision of AI. Algorithms for ML have the potential to optimize patient care, in that they can be utilized in a supportive way in personalized medicine, decision making and risk prediction. Although the majority of the applications in medicine are still limited to data analysis and research, it is certain that ML will become increasingly more important in scientific and clinical aspects in this supportive function. Therefore, it is necessary for clinicians to have at least a basic understanding of the functional principles, strengths and weaknesses of ML.

[Personality traits in anesthesiology : Results from a questionnaire-based requirements analysis]. / Persönlichkeitseigenschaften in der Anästhesiologie : Ergebnisse einer fragebogenbasierten Anforderungsanalyse.

BACKGROUND: Criteria for the identification of suitable applicants for undergraduate and postgraduate medical education are greatly and ubiquitously discussed. Apart from the acquisition of theoretical knowledge and practical skills, certain personality traits are necessary for practicing the medical profession; however, little is known on the personality traits required for medical subspecialties. This study had two objectives: 1) identification and evaluation of personality traits which are essential for performing anesthesiology and 2) establishment of a job specification for anesthesiology. METHODS: We performed a survey among German anesthesiologists using an online questionnaire. This questionnaire collected demographic data, such as age, gender, level of postgraduate education and 28 personality traits from 5 categories: cognition, psychomotor, physical, sensory and social interactive properties. The participants were asked to rate the personality traits on a 5-point Likert scale. Statistical analysis was performed using an ANOVA. RESULTS: A total of 714 questionnaires were analyzed. Social interactive skills and cognitive personality traits were considered as most important for a clinical career in anesthesiology. The three personality traits rated highest were a high decision-making ability, stress tolerance and speed of perception. Furthermore, a high apprehension, affability and patient-oriented behavior are needed. CONCLUSION: A job specification describing important personality traits can be useful to advise both undergraduates and postgraduates on their medical career and for medical team simulation tasks. For the clinical practice in anesthesiology, for example, high social interactive and cognitive personality traits are required.

Validation of a mobile app for reducing errors of administration of medications in an emergency.

Medication errors occur frequently and are a risk to patient safety. To reduce mistakes in the medication process in emergencies, a mobile app has been developed supporting the calculation of doses and administration of drugs. A simulation study was performed to validate the app as a tool to reduce medication errors. This was a randomised crossover study conducted in the Academic Hospital. The participants included were residents and attendings in anaesthesiology. 74 Participants performed four simulation scenarios in which they had to calculate and administer drugs for emergencies. Two scenarios were performed with the app ("app scenarios") and the other two scenarios were performed without the use of the app ("control scenarios"). The order of drugs, simulation patients and usage of aid were randomized. The accuracy of administered drug doses were measured. Medications were categorised as either "accurate" ([Formula: see text]% of target dosage) or "wrong" (less than 50% or more than 200% of target dosage). The dosage calculated and the dosage administered were documented separately to differentiate between calculation and handling errors. During app scenarios, there were no "wrong" dosages, whereas 6.8 (95% CI 2.7-10.8%) of dosages in control scenarios were evaluated as "wrong". The probability of giving an "accurate" dosage was increased from 77.7 (70.9-84.5%) in control scenarios to 93.9 (90-97.8%) in app scenarios. Calculation errors were the main cause for wrong dosing. The app is an appropriate and feasible tool to reduce calculation and handling errors and may increase patient safety.

[Analysis of the personnel development in anesthesiology over the last two decades with special attention to gender aspects]. / Eine Analyse der Personalentwicklung in der Anästhesiologie unter besonderer Berücksichtigung von Gender-Aspekten.

Skills shortage of nursing staff and physicians is a "hot topic" in health politics. For the future recruitment of medical staff in anesthesiology, an analysis of the staff development during the last decades considering gender aspects seems to be important. Therefore, the authors conducted a comparative analysis of data from the "Statistisches Bundesamt" (Fachserie 12 Reihe 7.3.1 and Fachserie 12 Reihe 6.1.1.) from 1994 until 2015. The analysis compared the development of anesthesiological staff (physicians) with the overall development of medical staff (physicians) in respect of the number of residents, consultants and department chairs. There are two major differences between the development of medical staff in anesthesiology and the overall development of medical staff: (1) in anesthesiology there is a high percentage of consultants without management tasks, (2) though the percentage of female colleagues is increasing both in anesthesiology and overall, the percentage of female colleagues in management or chair positions is lower in anesthesiology compared to the other disciplines, altogether. Anesthesiology is a discipline in which both the number of tasks and personnel have risen over the last two decades. The comparatively huge increase in the number of residents and consultants without management tasks suggests that the number of tasks in daily routine has substantially increased for anesthesiologists. The comparatively low percentage of female colleagues in chair positions should give an impulse to improve the compatibility of family and working live both for clinical and scientific careers.

[Enhanced recovery after surgery (ERAS®) in cardiac anesthesia]. / Enhanced Recovery After Surgery (ERAS®) in der Kardioanästhesie.

Enhanced Recovery After Cardiac Surgery (ERACS) is a multidisciplinary and multiprofessional treatment approach in cardiac surgery. Recently, a transfer and adaptation of enhanced recovery after surgery (ERAS) protocols from other disciplines, such as colorectal surgery, to cardiac surgery has been performed in different settings. First, prehabilitation programs have been established and investigated to improve patients' physical, psychological and nutritional status including treatment of preoperative anemia. Second, intraoperative therapeutic steps are described, such as infection reduction bundles, rigid sternal closure and guidance of perioperative anesthesia. For this, the use of short-acting agents, goal-directed fluid management and multimodal anesthesia are among the important measures. Third, early recovery and restoration of patient autonomy are achieved with early extubation and mobilization, efficient postoperative analgesia and diagnosis and treatment of delirium.The introduction of an ERACS protocol is a team effort requiring a protocol adapted to the institutional conditions and a willingness to perform a shift of culture in perioperative care. So far, the successful establishment of ERACS protocols in minimally invasive cardiac surgery has been reported and encourages the development of protocols of specific patient groups, such as pediatric cardiac surgery or left ventricular assist device implantation.

Respiratory systolic variation test in acutely impaired cardiac function for predicting volume responsiveness in pigs.

BACKGROUND: Predicting the response of cardiac output (CO) to volume administration remains difficult, in particular in patients with acutely compromised cardiac function, where, even small amounts of i.v. fluids can lead to volume overload. We compared the ability to predict volume responsiveness of different functional haemodynamic parameters, such as pulse pressure variation (PPV), stroke volume variation (SVV), the static preload parameter right atrial pressure (RAP), and global end-diastolic volume (GEDV) with the recently proposed respiratory systolic variation test (RSVT) in acutely impaired cardiac function. METHODS: In 13 mechanically ventilated pigs, cardiac function was acutely reduced by continuous application of verapamil to reach a decrease in peak change of left ventricular pressure over time (dP/dt) of 50%. After withdrawal of 20 ml kg(-1) BW blood to establish hypovolaemia, four volume loading steps of 7 ml kg(-1) BW using the shed blood and 6% hydroxyethylstarch 130/0.4 were performed. Volume responsiveness was considered as positive, if CO increased more than 10%. RESULTS: Receiver operating characteristic curve analysis revealed an area under the curve (AUC) of 0.88 for the RSVT, 0.84 for PPV, 0.82 for SVV, 0.78 for RAP, and 0.77 for GEDV. CONCLUSIONS: Functional parameters of cardiac preload, including the RSVT, allow prediction of fluid responsiveness in an experimental model of acutely impaired cardiac function.

[General anesthesia in a patient with idiopathic orthostatic hypotension]. / Allgemeinanästhesie bei einem Patienten mit idiopathischer orthostatischer Hypotonie.

Idiopathic orthostatic hypotension (formerly known as Shy-Drager syndrome) is a multiple system atrophy, which is characterized by autonomic dysregulation. Providing perioperative hemodynamic stability during narcosis is therefore a particular challenge. The effects of general anesthesia on systemic vascular resistance and cardiac output in a patient with idiopathic orthostatic hypotension undergoing retropubic prostatectomy will be reported. In the case presented perioperative hemodynamic stability was achieved by aggressive volume therapy guided by global end-diastolic volume measurement and low-dose catecholamine therapy.

Lung injury following thoracic aortic occlusion: comparison of sevoflurane and propofol anaesthesia.

BACKGROUND: Halogenated anaesthetics have been shown to reduce ischaemia-reperfusion injuries in various organs due to pre- and post-conditioning mechanisms. We compared volatile and total intravenous anaesthesia with regard to their effect on remote pulmonary injury after thoracic aortic occlusion and reperfusion. METHODS: Eighteen pigs were randomized after sternotomy and laparotomy (fentanyl-midazolam anaesthesia) to receive either sevoflurane or propofol in an investigator-blinded fashion. Ninety minutes of thoracic aortic occlusion was induced by a balloon catheter. During reperfusion, a goal-directed resuscitation protocol was performed. After 120 min of reperfusion, the anaesthetic regimen was changed to fentanyl-midazolam again for another 180 min. The oxygenation index and intra-pulmonary shunt fractions were calculated. After 5 h of reperfusion, a bronchoalveolar lavage was performed. The total protein content and lactate dehydrogenase activity were measured in epithelial lining fluid (ELF). Alveolar macrophage oxidative burst was analysed. The wet to dry ratio was calculated and tissue injury was graded using a semi-quantitative score. Ten animals (n=5 for each anaesthetic) without aortic occlusion served as time controls. RESULTS: The oxygenation index decreased and the intra-pulmonary shunt fraction increased significantly in both occlusion groups. There were no significant differences between sevoflurane and propofol with respect to the oxygenation index, ELF composition, morphologic lung damage, wet to dry ratio and alveolar macrophage burst activity. Differences were, however, seen in terms of systemic haemodynamic stability, where catecholamine requirements were less pronounced with sevoflurane. CONCLUSION: We conclude that the severity of remote lung injury was not different between sevoflurane and propofol anaesthesia in this porcine model of severe lower-body ischaemia and reperfusion injury.

Right ventricular stroke volume variation: a tool to assess right ventricular volume responsiveness.

BACKGROUND: So far, only left ventricular functional preload indices are used as a routine to assess volume responsiveness. Right ventricular (RV) functional preload indices have been described, but offer no continuous monitoring. METHODS: Following ethical approval, a pressure-induced right ventricular failure (RVF) was induced with continuous infusion of a thromboxane-A2-analogue (U46619) in 15 anesthetized and ventilated pigs. Before and after increasing mean pulmonary artery pressure (MPAP) by 50%, right ventricular stroke volume variation (RVSVV) was assessed with an ultrasonic pulmonary artery flow probe. Measurements were repeated following volume depletion (- 300 mL) and stepwise retransfusion (200 mL of whole blood and 200 mL of a colloid solution). RESULTS: A significant and systematic increase in RVSVV during induction of RVF was observed. Volume depletion led to an increase in RVSVV and re-transfusion led to a decrease in RVSVV. RVSVV was higher and a significant decrease in RVSVV was present in all animals experiencing an increase in CO by more than 5% during retransfusion. CONCLUSION: RVSVV seems to reflect volume requirement of the right ventricle and it might prove a reliable parameter to assess volume responsiveness in RVF.

Validation of pulse contour derived stroke volume variation during modifications of cardiac afterload.

BACKGROUND: Left ventricular stroke volume variation (SVV) or its surrogates are useful tools to assess fluid responsiveness in mechanically ventilated patients. So far it is unknown, how changes in cardiac afterload affect SVV. Therefore, this study compared left ventricular SVV derived by pulse contour analysis with SVV measured using an ultrasonic flow probe and investigated the influence of cardiac afterload on left ventricular SVV. METHODS: In 13 anaesthetized, mechanically ventilated pigs [31(SD 6) kg], we compared cardiac output (CO), stroke volume (SV), and SVV determined by pulse contour analysis and by an ultrasonic aortic flow signal (Bland-Altman analysis). After obtaining baseline measurements, cardiac afterload was increased using phenylephrine and decreased using adenosine (both continuously administered). Measurements were performed with a constant tidal volume (12 ml kg-1) without PEEP. RESULTS: Neither increasing mean arterial pressure (MAP) [from 59 (7) to 116 (19)] nor decreasing MAP [from 63 (7) to 39 (4)] affected CO, SV, and SVV (both methods). Method comparison revealed a bias for SVV of 0.1% [standard error of the mean (SE) 0.8] at baseline, -1.2% (SE 0.8) during decreased and 4.0% (SE 0.7) during increased afterload, the latter being significantly different from the others (P<0.05). Thereby, pulse contour analysis tended to underestimate SVV during decreased afterload and to overestimate SVV during increased afterload. Limits of agreement were approximately 6% for all points of measurement. CONCLUSIONS: Left ventricular SVV is not affected by changes in cardiac afterload. There is a good agreement of pulse contour with flow derived SVV. The agreement decreases, if afterload is extensively augmented.

Effects of sevoflurane and propofol on ischaemia-reperfusion injury after thoracic-aortic occlusion in pigs.

BACKGROUND: Thoraco-abdominal-aneurysm surgery predicts high mortality. Propofol and sevoflurane are commonly used anaesthetics for this procedure. Halogenated anaesthetics induce organ protection similar to ischaemic preconditioning. We investigated which anaesthetic regimen would lead to a better protection against ischaemia-reperfusion injury induced by temporary thoracic-aortic occlusion. METHODS: Following initial fentanyl-midazolam anaesthesia for surgical preparation, 18 pigs were randomly assigned to two groups: group one received propofol (n=9) and group two sevoflurane (n=9) before, during, and after lower body ischaemia in an investigator blinded fashion. Ten animals without aortic occlusion served as time controls (propofol, n=5; sevoflurane, n=5). For induction of ischaemia, the thoracic aorta was occluded by a balloon-catheter for 90 min. After 120 min of reperfusion, the study anaesthetics were discontinued and fentanyl-midazolam re-established for an additional 180 min. Goal-directed therapy was performed during reperfusion. Fluid and catecholamine requirements were assessed. Serum samples and intestinal tissue specimens were obtained. RESULTS: Severe declamping shock occurred in both study groups. While norepinephrine requirements in the sevoflurane group were significantly reduced during reperfusion (P<0.05), allowing cessation of catecholamine support in 4/9 animals, all 9/9 animals were still catecholamine dependent at the end of the experiment in the propofol group. Serum activities of lactate dehydrogenase, aspartate transaminase, and alanine aminotransferase were lower with sevoflurane (P<0.05). Small intestine tissue specimens did not differ histologically. CONCLUSIONS: Use of sevoflurane compared with propofol attenuated the haemodynamic sequelae of reperfusion injury in our model. Release of serum markers of cellular injury was also attenuated.

[Severe anaphylaxis from rocuronium]. / Schwere Anaphylaxie nach Rocuronium.

Muscle relaxant drugs are the most frequent cause of anaphylactic and anaphylactoid reactions during anaesthesia. We report a case of a life-threatening anaphylactic reaction during induction of anaesthesia with severe bronchospasm as the first clinical symptom. Mechanical ventilation was nearly impossible. The patient required a multimodal antiallergic therapy and a high-dose catecholamine therapy for stabilization. Rocuronium was identified as the allergic agent using intradermal testing.

The influence of PEEP and tidal volume on central blood volume.

BACKGROUND AND OBJECTIVE: Measurement of central blood volumes (CBV), such as global end-diastolic volume (GEDV) and right ventricular end-diastolic volume (RVEDV) are considered appropriate estimates of intravascular volume status. However, to apply those parameters for preload assessment in mechanically ventilated patients, the influence of tidal volume (TV) and positive endexpiratory airway pressure (PEEP) on those parameters must be known. METHODS: In 13 mechanically ventilated piglets, the effect of low (10 mL kg(-1)) and high (20 mL kg(-1)) TVs on CBV was investigated in absence and presence of PEEP (0 and 15 cm H(2)O). GEDV, RVEDV, right heart (RHEDV) and left heart end-diastolic volume (LHEDV) were measured by thermodilution. Blood flow on the descending thoracic aorta measured with an ultrasonic flow-probe served to determine stroke volume (SV). Measurements were performed during baseline conditions, after volume loading with previously extracted haemodilution blood (20 mL kg(-1)) and following haemorrhage (30 mL kg(-1)). RESULTS: Application of PEEP decreased GEDV and SV significantly (P < 0.05). Augmenting TV did not reduce GEDV systematically, but significantly reduced SV (P < 0.05). Changes in ventilator settings only influenced RVEDV following volume loading (P < 0.05). RHEDV and LHEDV decreased following application of PEEP, but only RHEDV decreased after augmenting TV at baseline and following volume loading. Correlation of SV with parameters of CBV was r = 0.487 (P < 0.01) for GEDV, r = 0.553 (P < 0.01) for RVEDV, r = 0.596 (P < 0.01) for RHEDV and r = 0.303 (P < 0.01) for LHEDV. CONCLUSION: Application of PEEP decreases CBV and SV. Augmenting TV reduces SV but not CBV. There is a moderate correlation between parameters of CBV and cardiac performance.