Introduction: The Nexfin device estimates arterial pressure by the volume clamp method through a finger pneumatic cuff. It also allows to estimate cardiac index (CI_noninv) by pulse contour analysis of the non-invasive arterial pressure curve. We evaluated the ability of the device to track changes in cardiac index induced by a fluid challenge. Methods: We included 45 patients for whom a volume expansion (500 mL of saline infused over 30 min) was planned. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution (CI_inv, PiCCO device) and in CI_noninv were recorded. Results: In seven patients, the Nexfin could not record the arterial curve due to finger hypoperfusion. Considering both the values obtained before and after volume expansion (n = 76 pairs of measurements), the bias (lower and upper limits of agreement) between CI_inv and CI_noninv was 0.2 (-1.8 to 2.2) L/min/m². The mean change in CI_noninv was 10 ± 11%. The percentage error of CI_noninv was 57%. The correlation between the changes in CI_inv and CI_noninv observed during volume expansion was significant (P = 0.0002) with an r² = 0.31. Conclusions: The estimation of CI by the Nexfin device in critically ill patients is not reliable, neither for estimating absolute values of CI nor for tracking its changes during volume expansion.

Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Simulator-based teaching for coronary angiography (CA) is a seductive educational tool for medical students to improve knowledge and skills. Its pedagogical impact has not been fully evaluated yet. Objective: The aim of this study was to compare traditional face-to-face teaching with a simulator-based teaching. Methods: 118 students, in their 4th to 6th year of medical school, were prospectively randomized in two groups: a control teaching group (n=59, CONT group) and a simulator (Mentice AB, Sweden) group (n=59, SIM group). CONT group received a PowerPoint-based course whereas SIM group received a simulator-based course including exactly the same information in an interactive environment. After the course, students were evaluated by 40 multiple choice questions (maximum of 100 points (pts)), including questions on coronary anatomy (part1), angiographic projections (part2) and real case interpretations (part3). Results: Student characteristics were identical in both groups: 52.5% were female; age was 22.6±1.4 years. 35.6% were in their 4th year, 35.6% in 5th year and 28.8% in 6th year. SIM students scored higher than CONT students irrespective of age and year of medical school (59.5±10.8 vs. 43.7±11.3pts,p<0.00001) for all parts of the evaluation (part1: 36.9±6.6 vs. 29.6±6.9pts,p<0.00001; part2: 5.9±3.0 vs. 3.1±2.8pts,p<0.00001; and part3: 16.8±6.9 vs. 10.9±6.5pts,p<0.00001). Student satisfaction was also higher in SIM group than in CONT group (98% vs. 75% p<0.0001). Conclusions: This trial suggests that simulator-based teaching in CA significantly improves students' knowledge in coronary anatomy and angiography projections, as well as clinical and decision-making competences. These results should encourage further evaluation of simulator-based teaching in other branches of medicine.