Early Bird or Night Owl: Insights into Dutch Students' Study Patterns using the Medical Faculty's E-learning Registrations.

Phenomenon: Educational activities for students are typically arranged without consideration of their preferences or peak performance hours. Students might prefer to study at different times based on their chronotype, aiming to optimize their performance. While face-to-face activities during the academic schedule do not offer flexibility and cannot reflect students' natural learning rhythm, asynchronous e-learning facilitates studying at one's preferred time. Given their ubiquitous accessibility, students can use e-learning resources according to their individual needs and preferences. E-learning usage data hence serves as a valuable proxy for certain study behaviors, presenting research opportunities to explore students' study patterns. This retrospective study aims to investigate when and for how long undergraduate students used medical e-learning modules. Approach: We performed a cross-sectional analysis of e-learning usage at one medical faculty in the Netherlands. We used data from 562 undergraduate multimedia e-learning modules for pre-clinical students, covering various medical topics over a span of two academic years (2018/19 and 2019/20). We employed educational data mining approaches to process the data and subsequently identified patterns in access times and durations. Findings: We obtained data from 70,805 e-learning sessions with 116,569 module visits and 1,495,342 page views. On average, students used e-learning for 16.8 min daily and stopped using a module after 10.2 min, but access patterns varied widely. E-learning was used seven days a week with an hourly access pattern during business hours on weekdays. Across all other times, there was a smooth increase or decrease in e-learning usage. During the week, more students started e-learning sessions in the morning (34.5% vs. 19.1%) while fewer students started in the afternoon (42.6% vs. 50.8%) and the evening (19.4% vs. 27.0%). We identified 'early bird' and 'night owl' user groups that show distinct study patterns. Insights: This retrospective educational data mining study reveals new insights into the study patterns of a complete student cohort during and outside lecture hours. These findings underline the value of 24/7 accessible study material. In addition, our findings may serve as a guide for researchers and educationalists seeking to develop more individualized educational programs.

International multicentre review of perioperative management and outcome for catecholamine-producing tumours.

BACKGROUND: Surgery for catecholamine-producing tumours can be complicated by intraoperative and postoperative haemodynamic instability. Several perioperative management strategies have emerged but none has been evaluated in randomized trials. To assess this issue, contemporary perioperative management and outcome data from 21 centres were collected. METHODS: Twenty-one centres contributed outcome data from patients who had surgery for phaeochromocytoma and paraganglioma between 2000 and 2017. The data included the number of patients with and without α-receptor blockade, surgical and anaesthetic techniques, complications and perioperative mortality. RESULTS: Across all centres, data were reported on 1860 patients with phaeochromocytoma or paraganglioma, of whom 343 underwent surgery without α-receptor blockade. The majority of operations (78·9 per cent) were performed using minimally invasive techniques, including 16·1 per cent adrenal cortex-sparing procedures. The cardiovascular complication rate was 5·0 per cent overall: 5·9 per cent (90 of 1517) in patients with preoperative α-receptor blockade and 0·9 per cent (3 of 343) among patients without α-receptor blockade. The mortality rate was 0·5 per cent overall (9 of 1860): 0·5 per cent (8 of 517) in pretreated and 0·3 per cent (1 of 343) in non-pretreated patients. CONCLUSION: There is substantial variability in the perioperative management of catecholamine-producing tumours, yet the overall complication rate is low. Further studies are needed to better define the optimal management approach, and reappraisal of international perioperative guidelines appears desirable.

ANTECEDENTES: La cirugía de los tumores productores de catecolaminas puede complicarse por la inestabilidad hemodinámica intraoperatoria y postoperatoria. Se han propuesto distintas estrategias de manejo perioperatorio, pero ninguna ha sido evaluada en ensayos aleatorizados. Para evaluar este tema, se han recogido los datos de los resultados y del manejo perioperatorio contemporáneo de 21 centros. MÉTODOS: Veintiún centros aportaron datos de los resultados de los pacientes operados por feocromocitoma y paraganglioma entre 2000-2017. Los datos incluyeron el número de pacientes con y sin bloqueo del receptor α, las técnicas quirúrgicas y anestésicas, las complicaciones y la mortalidad perioperatoria. RESULTADOS: Los centros en su conjunto aportaron datos de 1.860 pacientes con feocromocitoma y paraganglioma, de los cuales 343 pacientes fueron intervenidos sin bloqueo del receptor α. La gran mayoría (79%) de las cirugías se realizaron utilizando técnicas mínimamente invasivas, incluido un 17% de procedimientos con preservación de la corteza suprarrenal. La tasa de complicaciones cardiovasculares fue de 5,0% en total; 5,9% (90/1517) en pacientes con bloqueo preoperatorio de los receptores α y 0,9% (3/343) en pacientes no pretratados. La mortalidad global fue del 0,5% (9/1860); 0,5% (8/1517) en pacientes pretratados y 0,3% (1/343) en pacientes no tratados previamente. CONCLUSIÓN: Existe una variabilidad sustancial en el manejo perioperatorio de los tumores productores de catecolaminas, aunque la tasa global de complicaciones es baja. Este estudio brinda la oportunidad para efectuar comparaciones sistemáticas entre estrategias de prácticas terapéuticas variables. Se necesitan más estudios para definir mejor el enfoque de manejo óptimo y parece conveniente volver a evaluar las guías internacionales perioperatorias.

Pharmacokinetic and pharmacodynamic interactions in anaesthesia. A review of current knowledge and how it can be used to optimize anaesthetic drug administration.

This review describes the basics of pharmacokinetic and pharmacodynamic drug interactions and methodological points of particular interest when designing drug interaction studies. It also provides an overview of the available literature concerning interactions, with emphasis on graphic representation of interactions using isoboles and response surface models. It gives examples on how to transform this knowledge into clinically and educationally applicable (bedside) tools.

Do intravascular hypo- and hypervolaemia result in changes in central blood volumes?

BACKGROUND: Hypovolaemia is generally believed to induce centralization of blood volume. Therefore, we evaluated whether induced hypo- and hypervolaemia result in changes in central blood volumes (pulmonary blood volume (PBV), intrathoracic blood volume (ITBV)) and we explored the effects on the distribution between these central blood volumes and circulating blood volume (Vd circ). METHODS: Six anaesthetized, spontaneously breathing Foxhound dogs underwent random blood volume alterations in steps of 150 ml (mild) to 450 ml (moderate), either by haemorrhage, retransfusion of blood, or colloid infusion. PBV, ITBV and Vd circ were measured using (transpulmonary) dye dilution. The PBV/Vd circ ratio and the ITBV/Vd circ ratio were used as an assessment of blood volume distribution. RESULTS: 68 blood volume alterations resulted in changes in Vdcirc ranging from -33 to +31%. PBV and ITBV decreased during mild and moderate haemorrhage, while during retransfusion, PBV and ITBV increased during moderate hypervolaemia only. The PBV/Vd circ ratio remained constant during all stages of hypo- and hypervolaemia (mean values between 0.20-0.22). This was also true for the ITBV/Vd circ ratio, which remained between 0.31 and 0.32, except for moderate hypervolaemia, where it increased slightly to 0.33 (0.02), P<0.05. CONCLUSIONS: Mild to moderate blood volume alterations result in changes of Vd circ, PBV and ITBV. The ratio between the central blood volumes and Vd circ generally remained unaltered. Therefore, it could be suggested that in anaesthetized spontaneously breathing dogs, the cardiovascular system maintains the distribution of blood between central and circulating blood volume.

Orthotopic Liver Transplantation in Glycogen Storage Disease Type 1a: Perioperative Glucose and Lactate Homeostasis

Abstract Glycogen storage disease type 1a (GSD 1a) is a rare inborn error of metabolism. It causes severe fasting intolerance and lactic acidosis due to the deficiency of glucose-6-phosphatase enzyme. Blood glucose and lactate concentrations from 2 patients with GSD 1a were retrospectively compared to a control group of patients with familial amyloid polyneuropathy. Carbohydrate intake and infusions were compared to experimental data based on stable isotope studies. Perioperative lactate concentrations were significantly higher in our 2 patients with GSD 1a (median 15.0 mmol/L; range 9.9-22.0 mmol/L) versus 8 controls. In one patient, despite normal blood glucose concentrations, lactate acidosis was probably caused by a combination of the disease itself, insufficient (par)enteral carbohydrate intake, Ringer lactate infusions, and circulatory insufficiency. Patients with GSD 1a carry an increased risk of lactic acidosis during orthotopic liver transplantation compared to non-GSD patients. Multidisciplinary perioperative care is essential to prevent significant complications.

Green light for liver function monitoring using indocyanine green? An overview of current clinical applications.

The dye indocyanine green is familiar to anaesthetists, and has been studied for more than half a century for cardiovascular and hepatic function monitoring. It is still, however, not yet in routine clinical use in anaesthesia and critical care, at least in Europe. This review is intended to provide a critical analysis of the available evidence concerning the indications for clinical measurement of indocyanine green elimination as a diagnostic and prognostic tool in two areas: its role in peri-operative liver function monitoring during major hepatic resection and liver transplantation; and its role in critically ill patients on the intensive care unit, where it is used for prediction of mortality, and for assessment of the severity of acute liver failure or that of intra-abdominal hypertension. Although numerous studies have demonstrated that indocyanine green elimination measurements in these patient populations can provide diagnostic or prognostic information to the clinician, 'hard' evidence - i.e. high-quality prospective randomised controlled trials - is lacking, and therefore it is not yet time to give a green light for use of indocyanine green in routine clinical practice.

Intraoperative ICG plasma disappearance rate helps to predict absence of early postoperative complications after orthotopic liver transplantation.

Early postoperative complications after orthotopic liver transplantation (OLT) are a common problem in intensive care medicine. Adequate assessment of initial graft function remains difficult, however, plasma disaperance rate of indocyanine green (PDRICG) may have an additional diagnostic and prognostic value in this setting. We retrospectively evaluated the ability of intraoperative PDRICG values to predict absence of early postoperative complications in 62 subjects. PDRICG was measured non-invasively by pulse dye densitometry during surgery and was correlated with initial graft function. At the end of surgery, PDRICG was higher in patients without complications: 24.9 % min(-1) (n = 40) versus 21.0 % min(-1), (n = 22; p = 0.034). An area under the ROC curve (AUROC) for PDRICG was 0.70, while the AUROC for pH, lactate and PT at ICU admission were 0.53, 0.50 and 0.46, respectively. The AUROC of serum bilirubin and PT at postoperative day 5 were 0.68 and 0.49, respectively. The optimal cut-off PDRICG value for predicting absence of development early postoperative complications was determined to be 23.5 % min(-1) with 72.4 % sensitivity and 71.0 % specificity. Intraoperative point-of-care PDRICG measurement during OLT already predicts absence of early postoperative complications, better and earlier than clinically used laboratory parameters.

Comparison of arterial pressure and plethysmographic waveform-based dynamic preload variables in assessing fluid responsiveness and dynamic arterial tone in patients undergoing major hepatic resection.

BACKGROUND: Dynamic preload variables to predict fluid responsiveness are based either on the arterial pressure waveform (APW) or on the plethysmographic waveform (PW). We compared the ability of APW-based variations in stroke volume (SVV) and pulse pressure (PPV) and of PW-based plethysmographic variability index (PVI) to predict fluid responsiveness and to track fluid changes in patients undergoing major hepatic resection. Furthermore, we assessed whether the PPV/SVV ratio, as a measure of dynamic arterial elastance (Eadyn), could predict a reduction in norepinephrine requirement after fluid administration. METHODS: Thirty patients received i.v. fluid (15 ml kg(-1) in 30 min) after hepatic resection and were considered responders when stroke volume index (SVI) increased ≥20% after fluid administration. SVV and SVI were measured by the FloTrac-Vigileo(®) device, and PVI was measured by the Masimo Radical 7 pulse co-oximeter(®). RESULTS: The areas under a receiver operating characteristic curve for SVV, PPV, and PVI were 0.81, 0.77, and 0.78, respectively. In responders, all dynamic variables, except PVI, decreased after fluid administration. Eadyn predicted a reduced norepinephrine requirement (AUC = 0.81). CONCLUSIONS: In patients undergoing major hepatic resection, both APW- and PW-based dynamic preload variables predict fluid responsiveness (preload) to a similar extent. Most variables (except PVI) also tracked fluid changes. Eadyn, as a measure of arterial elastance (afterload), might be helpful to distinguish the origin of hypotension. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT01060683.

Accuracy of non-invasive measurement of haemoglobin concentration by pulse co-oximetry during steady-state and dynamic conditions in liver surgery.

BACKGROUND: The Masimo Radical 7 (Masimo Corp., Irvine, CA, USA) pulse co-oximeter(®) calculates haemoglobin concentration (SpHb) non-invasively using transcutaneous spectrophotometry. We compared SpHb with invasive satellite-lab haemoglobin monitoring (Hb(satlab)) during major hepatic resections both under steady-state conditions and in a dynamic phase with fluid administration of crystalloid and colloid solutions. METHODS: Thirty patients undergoing major hepatic resection were included and randomized to receive a fluid bolus of 15 ml kg(-1) colloid (n=15) or crystalloid (n=15) solution over 30 min. SpHb was continuously measured on the index finger, and venous blood samples were analysed in both the steady-state phase (from induction until completion of parenchymal transection) and the dynamic phase (during fluid bolus). RESULTS: Correlation was significant between SpHb and Hb(satlab) (R(2)=0.50, n=543). The modified Bland-Altman analysis for repeated measurements showed a bias (precision) of -0.27 (1.06) and -0.02 (1.07) g dl(-1) for the steady-state and dynamic phases, respectively. SpHb accuracy increased when Hb(satlab) was <10 g dl(-1), with a bias (precision) of 0.41 (0.47) vs -0.26 (1.12) g dl(-1) for values >10 g dl(-1), but accuracy decreased after colloid administration (R(2)=0.25). CONCLUSIONS: SpHb correlated moderately with Hb(satlab) with a slight underestimation in both phases in patients undergoing major hepatic resection. Accuracy increased for lower Hb(satlab) values but decreased in the presence of colloid solution. Further improvements are necessary to improve device accuracy under these conditions, so that SpHb might become a sensitive screening device for clinically significant anaemia.