Background: To date, no study has explored the effect of bent length on lightwand intubation. For successful intubation in daily practice, the authors found that bent length should be approximated to the patient's thyroid prominence-to-mandibular angle distance (TMD), but some patients have a TMD much shorter than the suggested bent length range. The purposes of this study were to understand TMD distribution in adults and to test the influence of bent length on lightwand intubation.
Methods: The TMD, airway, and demographic data of 379 patients were collected. To test the bent length influence, patients were enrolled in group A (158 patients, TMD </= 5.5 cm) and group B (131 patients, TMD > 5.5 cm) and were intubated randomly using the lower (6.5 cm) and upper (8.5 cm) limits of the suggested range. Success rate and lightwand search time were compared.
Results: In group A, the success rate was 98.8% with 6.5-cm bent length and 78.2% with 8.5-cm bent length (P < 0.05). Search times were 5.7 +/- 2.90 and 8.9 +/- 5.80 s with 6.5- and 8.5-cm bent length, respectively (P < 0.01). In group B, there was no statistical difference in success rate and search time between 6.5- and 8.5-cm bent length.
Conclusion: The suggested range was suitable for patients in group B (TMD > 5.5 cm). However, in group A (</=5.5 cm), the large discrepancy between the upper limit of the suggested range and this TMD caused difficulty in lightwand intubation. A 6.5-cm bent length is more suitable than an 8.5-cm bent length in these patients.