RELIABILITY OF EXPERIENCED AND NOVICE CRITICAL CARE RATERS EVALUATING QUADRICEPS AND TIBIALIS ANTERIOR MUSCLE ULTRASOUND

F. González-Seguel¹, J. Molina¹, F. Ríos-Castro¹, A. Camus-Molina¹, A. Silva-Gutiérrez², J.J. Pinto-Concha³

¹Clínica Alemana Universidad del Desarrollo, School of Physiotherapy, Facultad de Medicina, Santiago, Chile, ²Hospital Clínico Herminda Martin, Unidad de Paciente Crítico Adulto, Chillán, Chile, ³Clínica INDISA, Unidad de Paciente Crítico Adulto, Santiago, Chile

Background: Muscle ultrasound is a valid tool to monitor quality and quantity of the muscle mass in critically ill patients. The level of experience and training is essential to the accuracy of the measurements.

Purpose: To evaluate the interobserver reliability of experienced and novice raters measuring muscle thickness and echo-intensity of the quadriceps and tibialis anterior.

Methods: Cross-sectional reliability study. Twenty-four critical care physiotherapists participated (5 experienced and 19 novice). The experienced raters had more than 4 years using ultrasound and the novices received for the first time theoretical (10 hours) and hands-on (6 hours) training just before of the measurements of this study. Following a standardized ultrasound protocol, each rater measured the thickness (centimeters) of the rectus femoris (RF), vastus intermedius (VI), quadriceps (Q), and tibialis anterior (TA) of the right lower limb of 10 healthy and young models. The measurements were performed using portable ultrasound devices with either linear or curvilinear probes. The Intraclass Correlation Coefficient 2-way random effect single measurement (ICC_2,1), Standard Error of Measurement (SEM), and the Minimal Detectable Change at 95% confidence interval (MDC₉₅) were calculated. Additionally, the novices scored the echo-intensity of 19 muscle ultrasound images of critically ill patients using the Heckmatt score. The agreement with experienced raters was evaluated (Spearman Rho).

Results: 960 muscle thickness measurements were performed (experienced=200 and novice=760). The mean thickness of the quadriceps and tibialis anterior was 4.4±0.77 and 2.4±0.35 centimeters for the experienced and 4.2±0.80 and 2.2±0.39 centimeters for the novices, respectively. The values of muscle thickness measured by novice raters were 5% lower than the values of the experienced raters (p<0.03). Experienced raters obtained excellent reliability for thickness of RF (ICC=0.80 [CI 95% 0.66–0.95]), VI (ICC=0.87 [0.77–0.97]), Q (ICC=0.82 [0.69–0.96]), and TA (ICC=0.86 [0.75–0.97]). Novice raters obtained moderate to good reliability for thickness of RF (ICC=0.46 [0.23–0.69]), VI (ICC=0.69 [0.51–0.89]), Q (ICC=0.76 [0.60–0.92]), and TA (ICC=0.41 [0.18–0.64]). The SEM ranged from 0.05 to 0.12, and the MDC₉₅ ranged from 0.14 to 0.33 centimeters. The mean Heckmatt score was 2.6±0.83 points, showing a reliability of ICC=0.68 and an agreement with the experimenters of 0.78 [p<0.001].

Conclusions: Interobserver reliability was excellent for experienced raters and moderate to good for novice raters, including muscle thickness and Heckmatt score assessments. The muscle thickness measured by the novices was systematically lower. Regardless of experience level, trained critical care physiotherapists obtained reliable quadriceps ultrasound measurements.

Implications: Considering our findings on the differences of muscle thickness values and reliability between experienced and novice raters, future studies should investigate if the recommended minimal compression technique is associated with lower reliability values; potentially useful for skeletal muscle ultrasound training.

Funding acknowledgements: None

Keywords:
Ultrasonography
Reliability
Critical care

Topics:
Critical care
Education
Musculoskeletal: lower limb

Did this work require ethics approval? Yes

Institution: Clínica Alemana Universidad del Desarrollo, Santiago, Chile

Committee: Ethics Committee of the Clínica Alemana Universidad del Desarrollo

Ethics number: #2020-106