Accuracy of fingerbreadth measurements for thyromental distance estimates: a brief report

There have been many contradicting studies as to how well preoperative airway assessments predict difficult intubation. One of these measures, thyromental distance (TMD), has often been called into question. However, there have been no published studies evaluating whether anesthesia practitioners are measuring TMD accurately, especially if they use fingerbreadths as opposed to a centimeter ruler. A convenience sample of 60 anesthesia providers were asked to participate in a brief study. The subjects were asked a series of questions, including the type of anesthesia provider they were, how often they used TMD, and their estimates in centimeters of the following fingerbreadth combinations: index finger, index and second finger, index plus second and third fingers, and index plus second, third, and fourth fingers. After their estimates were recorded, exact measurements of the fingerbreadth combinations were made at the distal interphalangeal (DIP) joints. The differences between the means of the estimated and the actual measurements were analyzed using an independent t test. There was a statistically significant difference between estimated and actual fingerbreadth measurement for the index finger (P < .006) but not for the combinations of fingers.