Anaesthesia
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Thyromental distance (TMD) measurement is commonly used to predict difficult intubation. We surveyed anaesthetists to determine how this test was being performed. Comparative accuracy of ruler measurement and other forms of measurement were also assessed in a meta-analysis of published literature. ⋯ In terms of distance, the minimum acceptable TMD was felt to be 6.5 cm by 55% of respondents. However, the actual width of three fingers was (range) 4.6-7.0 cm (mean 5.9 cm), with significant differences between genders and between proximal and distal interphalangeal joints. The meta-analysis showed ruler measurement increased test sensitivity (48% (95% CI 43-53) vs 16% (95% CI 14-19) without a ruler), when predicting difficult intubation.