Comparison of upper limb muscle activity and workload during intubation with the Macintosh direct laryngoscope versus C-MAC® and King Vision® videolaryngoscopes in simulated difficult airway scenarios: a randomized crossover trial
Authors' conclusion
In simulated difficult airways, VL reduced upper limb muscle activity compared with DL. Nevertheless, perceived workload was higher with King Vision VL than with DL, whereas it was lower with C-MAC VL. Among the devices tested, C-MAC VL provided the most favorable ergonomic balance, combining reduced muscle strain, lower perceived workload, and highest first-attempt success rate across all airway scenarios.
Study context
- Population
- Experienced anesthesiologists performing tracheal intubation on a high-fidelity manikin with a normal airway, locked jaw, and rigid neck
- Participants
- 35 experienced anesthesiologists
- Comparison
- Direct laryngoscopy (DL) vs videolaryngoscopy (VL) in simulated difficult airway scenarios
- Primary endpoint
- Upper limb muscle activity (brachioradialis), measured by surface electromyography
Methodological detailssimulated difficult airway scenarios, high-fidelity manikin
- Simulated difficult airway scenarios
- High-fidelity manikin
Primary result
As reported in the abstract
Estimate (95% CI)P value
DL vs C-MAC VL
median difference(MD), normal airway (16 vs 13 µV) 3 µV (0–5)
P = 0.04DL vs C-MAC VL
median difference(MD), locked jaw (18 vs 12 µV) 6 µV (1–11)
P = 0.02DL vs C-MAC VL
median difference(MD), rigid neck (16 vs 13 µV) 4 µV (0–9)
P = 0.03Secondary outcomes
| Outcome | P value |
|---|---|
| Perceived workload (NASA-TLX score)King Vision VL vs DL | P < 0.001 compared with DL |
- Perceived workload (NASA-TLX score): King Vision VL associated with the highest NASA-TLX workload score; C-MAC VL least demanding
Intubation time
- Direct laryngoscopy was the fastest method
Force on upper incisors
- Direct laryngoscopy exerted the highest force on the incisors
- P < 0.001
Original publication
Comparison of upper limb muscle activity and workload during intubation with the Macintosh direct laryngoscope versus C-MAC® and King Vision® videolaryngoscopes in simulated difficult airway scenarios: a randomized crossover trial. Can J Anaesth. Published 26 October 2026. doi:10.
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