Vergleich der Vorhersage einer erschwerten Intubation mit etablierten Methoden zur Prädiktion der schwierigen Laryngoskopie

Prediction of unexpected difficult endotracheal intubation is a common but unresolved problem. In literature difficult intubation is often defined by the laryngoscopic view, classified by Cormack and Lehane. In this study we also consider an "aggravated" intubation, classified as "Severity Degree of Intubation" (SDI). We define an intubation as aggravated when more than one intubation attempt is necessary. This paper explores the question whether usual methods of predicting difficult intubation can also be applied to predict aggravated intubation. For this purpose 175 patients without known intubation obstructions, undergoing elective trauma surgery, were evaluated using a prospective randomized and double- blinded protocol. The oropharyngeal view classified by Samsoon and Young, the length of the mandible, the thyromental distance and the interincisor gap were measured before the operation. The laryngoscopic view classified by Cormack and Lehane, the number of intubation attempts, the subjective impression and the intubation time were recorded during induction of general anesthesia. 9 patients (5 %) had a laryngoscopic view graded Cormack III-IV. In 23 cases (13 %) more than one intubation attempt was necessary. There are significant more patients with Samsoon and Young class III-IV within the Cormack and Lehane group III-IV. There is also a trend towards smaller mouth opening and shorter thyromental distance. In the aggravated SDI group only the mouth opening is determining for more than one intubation attempt. The actual diagnostic value of all predictive variables is low, with best results for small mouth opening in both result groups. Correlation between both result groups is weak. The SDI seems to be slightly more appropriate to represent the subjective impression. Neither subjective impression, nor outcome variables are depending on the qualification of a physician. Only the intubation time is depending on medical training. Apparently a specialist has same problems as a resident, but is able to solve them faster. We consider common methods of predicting difficult intubation also to be applicable to predict aggravated intubation. Mouth opening seems to have a special importance, but the diagnostic value for prediction of the aggravated intubation is still less useful compared to prediction of the difficult intubation.