Objectives: We assessed the likelihood of arytenoid dislocation during intubation through the application of controlled force.
Methods: Six cadaveric human larynges were mounted in an apparatus for simulating forcible collision with the arytenoid complexes. An endotracheal tube tip probe (ETTP) was used to push one arytenoid complex, and a non-slip probe (NSP) was tested on the other. Increasing pressure was applied until the probes either slipped or reached 5 kg of force. Dissection was then performed to assess the integrity of the cricoarytenoid ligament. The forces obtained by pushing an endotracheal tube against an electronic balance were measured to estimate the maximal possible intubating force.
Results: None of the ETTP or NSP trials disrupted the cricoarytenoid joint ligaments, and the joint never appeared to be dislocated. The mean maximal forces were 1.8 kg for the ETTP (after which, slippage consistently occurred) and 4.7 kg for the NSP. The mean maximal forces from an endotracheal tube pushed against a scale were 1.5 kg (without stylet) and 4.6 kg (with stylet).
Conclusions: Arytenoid dislocation did not happen, and gross disruption of the joint capsule or ligament did not occur, even when the testing approximated the maximum force achievable under extreme conditions. Endotracheal tube insertion thus seems unlikely to cause arytenoid dislocation.