The Accuracy Of The Middle Finger Length On Predicting Tracheal Tube Depth In Patients With Different Ages

Objective:It is very important with an appropriate tracheal intubation depth during general anesthesia.At present,the principle of 23 cm in man and 21cm in woman for tracheal tube depth were used in adult,the formula based on age(age/2+12)cm was used in children,but the accuracy of these methods were not high enough.In clinic,we found that three times middle finger length could use for tracheal tube depth.Thus,we plan to investigate the accuracy of three times middle finger length for predicting appropriate tracheal intubation depth by oral in different age patients.Methods:Part Ⅰ:Ninety-eight adult patients with ASA Ⅰ～Ⅲ grade,aged form 18 yrs to 84 yrs,undergoing general anesthesia were enrolled in this study.After general anesthesia induction,the depth of main trachea was measured by fiber bronchoscope.The tracheal tube was inserted with three times middle finger length,and the distance from carina to the tip of tracheal tube was measured.The distance from the upper border of tracheal tube cuff to the tip of tracheal tube was also measured.The distance from the upper border of tracheal tube cuff to vocal cords and the optimal tracheal depth were calculated.Then,the appropriate tracheal tube depth rate and the correlation between middle finger length and the optimal tracheal depth could obtained and they were compared with the principle of 23cm in man and 21cm in woman for tracheal tube depth.Part Ⅱ:Sixty-nine children with ASA Ⅰ～Ⅲ grade,aged form 4 yrs to 17 yrs,undergoing general anesthesia were enrolled in this study.After general anesthesia induction,the depth of main trachea was measured by fiber bronchoscope.The tracheal tube was inserted with three times middle finger length,and the distance was measured from carina to the tip of tracheal tube.The distance from the upper border of tracheal tube cuff to the tip of tracheal tube was also measured.The distance from the upper border of tracheal tube cuff to vocal cords and the optimal tracheal depth were calculated.Then,the appropriate tracheal tube depth rate and the correlation between middle finger length and the optimal tracheal depth could obtained and they were compared with the formula based on age for tracheal tube depth in children.Results:Part Ⅰ:A total of 98 adult patiens were enrolled in this study.When the endotracheal intubation depth was three times middle finger length,the appropriate tube placement rate was 87.7%,with 7 patients distal intubation(7.1%)and 5 patients proximal intubation(5.1%).When the endotracheal intubation depth was with the principle of 23cm in man and 21cm in women,the appropriate tube placement rate was 65.3%,with 5 patients distal intubation(5.1%)and 29 patients proximal intubation(29.6%).Copmared with the principle of 23cm in man and 21cm in women,the correlation between the optimal endotracheal intubation depth and middle finger length was stronger in the middle finger length methods(0.774 vs 0.477).Part Ⅱ:A total of 67 children were enrolled in this study.When the endotracheal intubation depth was three times middle finger length,the appropriate tube placement rate was 88.1%,with 3 patients distal intubation(4.4%)and 5 patients proximal intubation(7.4%).When the endotracheal intubation depth was with the formula based on age,the appropriate tube placement rate was 50.7%,with 33 children proximal intubation(49.3%).Copmared with the formula based on age,the correlation between the optimal endotracheal intubation depth and middle finger length was stronger in the middle finger length methods(0.940 vs 0.884).Conclusion:Our data indicate that the three times middle finger length can be used to predict the tracheal intubation depth accurately in the patients with age over 5 years.The middle finger method provides an additional strategy to confirm appropriate tube placement depth.It can be generalized in primary hospital.