[Difficult intubation in adults]

GOAL OF THIS REVIEW: We review the recent literature and our experience in order to determine how one can recognize and handle patients with difficult endotracheal intubation.

"An intubation is called difficult if a normally trained anesthesiologist needs more than 3 attempts or more than 10 min for a successful endotracheal intubation." The incidence of difficult intubation depends on the degree of difficulty encountered showing a range of 1-18% of all intubations to about 2/10000-1/million for "cannot ventilate-cannot intubate" situations. Three "cannot ventilate-cannot intubate" situations are presented that occurred at our institution in the last 10 years out of about 85000 anaesthesias.

Intubation will be overtly difficult in patients with a small mouth opening, protruding upper teeth, a stiff neck, engorgement of the tongue, cervical swelling after an operation for a face tumour, or in patients with an unstable cervical spine. In about 50-70%, a difficult intubation can be detected preoperatively in patients with grossly normal cervical anatomy by three indirect signs: if the soft palate cannot be visualized (Mallampati classification), if the inframandibular space is smaller than normal, and if the mobility of the atlanto-occipital joint is reduced to below 15 degrees. It is essential that these indirect parameters be tested preoperatively, especially in patients in whom general anaesthesial is planned for a caesarean section or if an ileus intubation is planned.

General handling of difficult intubation, use of special material including a portable unit, and confirmation of the endotracheal position of an endotrachaeal tube are outlined (CO2 et, SaO2, fibreoptic bronchoscopy, direct visualization of the translaryngeal position of the tube). The laryngeal mask airway, transtracheal jet ventilation, and the mini-coniotomy are selectively presented as alternative airways. The American Society of Anesthesiologists' (ASA) difficult airway algorithm is presented.

With better preoperative evaluation and clear guidelines and training for difficult intubation anaesthetic morbidity and mortality can be reduced.