Study design
A cross-sectional observational study was conducted to evaluate the results of the first Chilean muscle ultrasound education programme focused on ICU patients (eMUSICS, stand for: Education in Muscle Ultrasound for Intensive Care Setting) performed between August 19th and 31st, 2019 (https://bit.ly/2PvTWzt) in the faculty of medicine of a Chilean private university, which has a structured continuing education platform. This study received review and approval after course development by the research ethics committee of Universidad del Desarrollo (registration number 2020-106).
Instructors
Five critical care physiotherapists (ACM, JJP, FRC, ASG and FGS) with more than two years of ultrasound clinical experience led the eMUSICS. Instructors had received formal training from one of the following three alternatives: 1) Ultrasound in Emergency and Critical Care (USECC) course of the Sociedad Chilena de Medicina Crítica y Urgencias, 2) Ecografía en el Paciente Crítico as a 2017 pre-congress workshop at the Congreso Argentino of the Sociedad Argentina de Terapia Intensiva, or 3) Diagnostic ultrasound course as a 2017 post-congress workshop at the World Confederation of Physical Therapy Conference[23]. Two months before the course, all instructors carried out two 3-hour training meetings amongst themselves to standardize the methodology of image acquisition and measurement. The aim of this study was to evaluate the participants, however, the intra and inter-reliability of instructors performed prior to course initiation were presented in the results section for transparency. Reliability measurement procedure of instructors is presented in Additional file, Table S1.
Programme description
A 20-hour muscle ultrasound education programme was developed based on international training recommendations[20–22, 25]. Selected contents and materials from an ultrasound post-congress workshop developed in the 2017 World Confederation of Physical Therapy Conference[23] were used in this programme with prior authorization (SMP), involving ultrasound physics, knobology, muscle anatomy and physiology, patient positioning, landmarks, image acquisition and lower limb measurements of muscle quality and quantity. The course was designed for rehabilitation clinicians with at least 1 year of working experience with ICU patients. The ultrasound-training course was delivered in two parts – the first was online learning (eLearning) and the second in-person learning including a combination of lectures and hands-on practice (Additional file, Table S2 provides a detailed programme curriculum).
eLearning training and assessment
The eLearning was available for participants 2 weeks before the in-person course using the Moodle™ online platform with an estimated dedication time of 6 hours. The objectives of the eLearning were to identify the normal anatomical structures with real ultrasound images and to understand initial concepts of muscle structure measurements using ultrasound. The online platform included recommended pre-reading material, ultrasound machines technical manuals, an instructor-led discussion forum to answer questions, and four training videos (for more details on training videos see Additional file, Table S3). To guarantee the participant’s knowledge before the in-person course, a formative questionnaire with 20-question open-ended based on the observation of normal muscle ultrasound images was performed, which was answered using the pre-reading material provided. Participants submitted their answers until one day before the in-person course using the online platform.
In-person course
After the eLearning, the in-person course was performed during 2 consecutive days including 5-hours of didactic lectures and 9-hours of hands-on training led by 5 trained instructors. Lectures were conducted with a projector/screen using standard slide sets or real-time ultrasound muscle scanning of a participating volunteer. During hands-on training, 10 ultrasound machines were available, including 9 wireless (Philips Lumify, Sonus SL-2C, and Sonus DUO LCP) connected to an iPad; and one portable (Philips InnoSight, including linear and curvilinear array transducer). To optimize participant learning, a maximum of 20 participants was defined to achieve an instructor to trainee ratio of 1:4 and ultrasound machine to trainee ratio of 1:2 being more than the recommended ratio of 1:5 by the Australian Society of Ultrasound Medicine (see link: http://www.asum.com.au/files/public/Education/CAHPU/CAHPUForms/CAHPU-Unit-Accreditation-Application-Form.pdf). Knobology, patient positioning, landmarks, image acquisition, muscle thickness, and fiber pennation angle measurement were studied through lectures and hands-on training. The hands-on training was designed for each participant to perform 15 landmarks identifications and 25 supervised muscles scans including all ultrasound parameters involved in this study using the quadriceps measurements of the same participants.
Participant assessments: Theoretical knowledge was evaluated using a pre-course diagnostic questionnaire at the beginning of the in-person course. At the end of the course, theoretical knowledge was re-evaluated through a post-course formative questionnaire using the same questions in a randomly assigned order. Both questionnaires included 25 multiple-choice questions of which 11 were obtained from the questionnaire of Ntoumenopoulos et al[23].
Hands-on assessment was performed during the last 3 hours of the course to assess the practical skills of participants. Due to class size and timing convenience, participants were split into groups to perform the hands-on assessment and inter-rater reliability. Using the ©Intemodino RNG as random number generator software, participants were distributed into 5 groups of 4 people. The participants were blind to each other's measurements to assess: quadriceps landmarks; rectus femoris (RF), vastus intermedius (VI), quadriceps complex (QC) thickness; and/or vastus lateralis (VL) pennation angle in 6 healthy individuals. The ultrasound machine to trainee ratio was 1:2, and each instructor qualitatively evaluated four participants through direct observation using a non-middle answer category Likert scale from 1 to 4 points (1 = poor, 2 = fair, 3 = good, 4 = excellent)[26]. This scale was used to evaluate the performance of the following items: patient positioning, landmarks identification, knobology operation (accurate use of gain compensation, zoom, focus, depth, freeze function and caliper), image acquisition (anatomy identification), transducer placement and quadriceps measurements. Participants measured the landmarks and muscle thickness in centimeters and pennation angle in degrees on a pre-specified written record document. Participants were previously trained to capture all ultrasound images directly on the ultrasound machine, and subsequently instructors exported without any adjustments to a computer for analysis using a data storage device. This data was used to evaluate inter and intra-rater reliability of participants according to the assigned group. Reliability measurement procedure of participant is presented in supplemental material, Table S1, and was informed following the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) standards to assess the quality of studies on reliability and measurement error[27].
Course measurement protocol of landmarks, muscle thickness and pennation angle
Participants were examined in the supine position with neutral rotation and passive extension of lower limb[2]. Anatomical landmarks were marked using an erasable skin marker and measured in centimeters using a flexible tape measure. Quadriceps landmark was defined as the midpoint between the anterior superior iliac spine and the superior patella border[28, 29]. Tibialis anterior landmark was defined as one third of the distance from the tibial plateau to the inferior border of lateral malleolus[28, 29]. Depending on specific thigh size a B-mode with linear (4 to 12 MHz) and curvilinear (5 to 2 MHz) array transducers was used. When required, participants adjusted gain compensation, zoom, focus, depth, and freeze function. A generous amount of contact gel was used to minimize the required pressure of the transducer on the skin, allowing the minimal compression technique. Scans were performed with the transducer in neutral tilt using a transverse cross-sectional view for the muscle thickness and a sagittal view for the pennation angle. The transverse cross-sectional view was acquired to measure RF, VI and QC muscle thickness[30–32]. Muscle thickness were reported in centimeters using the caliper of the ultrasound machine as the inside height measured between epimysial borders of each muscle[2] (Additional file, Figure S1). To acquire an accurate sagittal view for VL pennation angle, the transducer was moved laterally 5 centimeters from the site where RF/VI was obtained. Pennation angle of the VL was reported in degrees as the angle between direction of muscle fibers and force line action represented by external tendon or aponeurosis i.e., the vertical inclination of fibers from the long axis of muscle[33], using the average of three consecutive separate attempts (Additional file, Figure S2).
Course satisfaction
At the end of the second day of the in-person course, participants were asked to voluntarily answer a standardized anonymous satisfaction survey predesigned by the local university educational programme and used for all courses related to medicine. This survey evaluates the participant perception including the overall assessment of the course, academic scope, instructor quality, eLearning, pre-reading material and course coordination. Each item was scored using a non-middle answer category Likert scale from 1 to 4 points (1 = Strongly disagree, 2 = Disagree, 3 = Agree, 4 = Strongly agree)[26]. Additionally, this survey included the following two yes-no questions: would you recommend these instructors for a future course?, and would you recommend this program to other people?.
Statistical analyses
Descriptive data were analyzed using STATA SE 15.0 (StataCorp, LLC, 2017, College Station, TX). The normality of the data of each variable was analyzed with the Shapiro-Wilk test. Data were described as mean ± standard deviation (SD) or median (interquartile range [IQR]), depending on the normality of the data. The limit of statistical significance was set at two-sided p value of ≤0.05. The scores of knowledge and practical skills questionnaires and satisfaction survey were reported as percentage correct. Reliability of participants and instructors was calculated using the intraclass correlation coefficient (ICC) and 95% CI according to Koo et al[34]. Repeated measurements by the same rater on the same subject were used to calculate intra-rater reliability that included a brief period with the instructor removing previous test results. Repeated measurements by different raters on the same subject were used to calculate inter-rater reliability, while raters were blinded to the test and results of the other raters. Inter-rater reliability was calculated using the 2-way random effects, absolute agreement, average measure of the number of records; and intra-rater reliability was calculated using the 2-way mixed effects, absolute agreement, single measure (Additional file, Table S3). Group comparisons were not performed, as this was not the focus of the study. To obtain the overall inter-rater reliability of the five groups of participants, the median and IQR of the ICC values of each ultrasound parameter was calculated. The qualitative interpretation of the ICC was classified as 0.00 (absent), 0.00–0.19 (poor), 0.20–0.39 (weak), 0.40–0.59 (moderate), 0.60–0.79 (good), and ≥0.80 (excellent)[35]. The standard error of measurement (SEM) was calculated for each ICC value as the product of standard deviation and the square-root (1 – single measures ICC). Coefficient of variation (CV) was calculated using the division of the SD by the mean value of the repeated measures (CV= [SD/mean]*100); interpreted as CV<10 (very good), 10-20 (good), 20-30 (acceptable), and CV>30 (not acceptable)[36, 37].