Ergonomic task analysis of ultrasound-guided femoral nerve block: a pilot study

Study Objective

To apply ergonomic task analysis to the performance of ultrasound-guided (US-guided) femoral nerve block (FNB) in an acute hospital setting.

Design

Pilot prospective observational study.

Setting

Orthopedic operating room of a regional trauma hospital.

Subjects

15 anesthesiologists of various levels of experience in US-guided FNB (estimated minimum experience < 10 procedures; maximum about 50 procedures, and from basic trainees to consultants); and 15 patients (5 men and 10 women), aged 77 ± 15 (mean ± SD yrs) years.

Measurements/Observations

A data capture “tool”, which was modified from one previously developed for ergonomic study of spinal anesthesia, was studied. Patient, operator, and heterogeneous environmental factors related to ergonomic performance of US-guided FNB were identified. The observation period started immediately before commencement of positioning the patient and ended on completion of perineural injection. Data were acquired using direct observations, photography, and application of a questionnaire.

Main Results

The quality of ergonomic performance was generally suboptimal and varied greatly among operators. Eight (experience < 10 procedures) of 15 operators excessively rotated their head, neck, and/or back to visualize the image on the ultrasound machine. Eight operators (experience < 10 procedures) performed the procedure with excessive thoracolumbar flexion.

Conclusion

Performance of US-guided FNB presents ergonomic challenges and was suboptimal during most of the procedures observed. Formal training in US-guided peripheral nerve blockade should include reference to ergonomic factors.