Abstracts and Programme: EUROANAESTHESIA 2011: The European Anaesthesiology Congress: Airway Management
Background and Goal of Study: The aims of this study were to examine the relationships between the size of oropharyngeal airways(OPAs) and various external body measurements and to determine the proper size of OPAs for adults.
Materials and Methods: After obtaining approval from the IRB and informed consent, 50 subjects with ASA physical status I‐II (22 male and 28 female) aged 20‐75 years were enrolled. Before anesthesia, the distances from the tra‐ gus of the ear to the lateral border of the nares (TN distance) and to the lateral border of mouth (TM distance) were measured. During induction, we mea‐ sured the curvilinear length of the Macintosh laryngoscope from the upper incisor to the tip of the epiglottis (IE distance). After induction, different sizes of OPAs (Guedel airway) (Nos.8, 9, 10, and 11) were inserted sequentially and we measured the distance from the upper incisor that touches the OPA to the tip of the epiglottis by passing the fiberoptic bronchoscope via channel of the OPA. When the length of OPAs was longer than that distance, we partly drew out the proximal part of the OPAs and repositioned the distal end around the tip of the epiglottis.
Results and Discussion: The distances among IE (10.9 ± 0.9cm), TN (11.0 ± 0.6cm), and TM (10.0 ± 0.6cm) were similar(NS). In Table 1, the length of OPAs No.8 and 9 appeared to be shorter while OPAs No. 10 and 11 were longer than the distance from the upper incisor to the tip of the epiglottis. The correlation between the TN or TM distance and height were significant in both the TN (r=0.405, P< 0.001) and TM (r =0.534; P < 0.001) groups. The formula of the regression lines (with 95% prediction intervals) for the TN and TM groups were Y = 0.260X +6.790 and Y = 0.361X +5.032, respectively (X axis, height). Considering the similarity between IE and TN or TM distances, based on the range of TN distance (98‐122 mm, 2 SD), the proper size of OPAs would be predicted to be OPAs No. 10 and 11. However, these OPA sizes did not ap‐ pear to be proper because they were longer than the distance from the upper incisor to the tip of the epiglottis.
Conclusion: TN or TM distance is not a likely predictor of proper OPA size. OPA of size No. 9 is likely to be suitable for use in adults.