Background: To determine the correct size of endotracheal tubes (ETT) for endotracheal intubation of pediatric patients, new methods have been investigated. Although the three-dimensional (3D) printing technology has been successful in the field of surgery, there are not many studies in the field of anesthesia. The purpose of this study is to evaluate the accuracy of a 3D airway model for prediction of the correct ETT size, and compare the results with a conventional age-based formula in pediatric patients.Methods: Thirty five pediatric patients under 6 years of age who were scheduled for congenital heart surgery. In the pre-anaesthetic period, the patient's computed tomography (CT) images were converted to STL (Standard Triangle Language) files using the 3D conversion program. An FDM (Fused Deposition Modelling) type 3D printer was used to print 3D airway models from the subglottis to the upper carina. ETT size was selected by inserting various sized cuffed-ETTs to a printed 3D airway model. Results:The 3D method selected the correct ETT size in 21 out of 35 pediatric patients (60%), whereas the age-based formula selected the correct ETT size in 9patients (26%).Conclusions: Prediction of correct size ETTs using a printed 3D airway model has demonstrated better results than the age-based formula. In particular, the selection of ETT size using a printed 3D airway model may be feasible for helping minimize re-intubation attempts and complications in the patients with congenital heart disease or an abnormal range of growth and development.

Background: PRS patients have an increased risk of difficult intubation due to anatomical airway abnormalities, and intubation simulation with a 3D printed airway model before anesthesia may facilitate safe airway management. Case: We describe the case of a 6.5-year-old boy with a history of Pierre Robin sequence (PRS, a triad of micrognathia, glossoptosis, and airway obstruction), tracheostomy, and subglottic fibrosis who required general anesthesia. Preparation for this potentially difficult intubation included estimation of endotracheal tube size using a three-dimensional (3D) printed airway model derived from 3D computed tomography of the airway, which enabled successful endotracheal intubation via video laryngoscopy. Conclusions: If general anesthesia is necessary in patients with dysmorphic features such as PRS and there is a history of tracheal pathology, the possibility of difficult intubation should always be considered and simulation of endotracheal intubation using a 3D printed model of the airway can be helpful clinically in such situations.

Background: The catheter-through-needle (CTN) method involves the insertion of a catheter with an outer diameter smaller than the initial puncture hole. We investigated whether the catheter-over-needle (CON) method is more effective than the CTN method in local anesthetic leakage at the catheter insertion site and catheter dislodgement, and how it affects postoperative pain management. Methods: Seventy patients scheduled to undergo continuous femoral nerve block for pain control following total knee arthroplasty were enrolled and randomized to receive a perineural catheterization with either the CTN method (group CTN) or CON method (group CON). After ultrasound-guided catheterization, the transparent securement dressing was attached. The study compared the CON and CTN methods in terms of leakage at the catheter insertion site, catheter dislodgement, and postoperative analgesic efficacy for 48 hours postoperatively. Results: Leakage at the catheter insertion site was significantly lower in the group CON ( P < .05), while catheter dislodgement was not significantly different between the groups. The other adverse events were not different between the groups. The procedure time was significantly shorter in group CON ( P < .05). No significant intergroup differences were observed 48 hours postoperatively in the visual analog scales, the number of patients requiring additional analgesics, and the number of times a bolus dose was injected with an injection pump. Conclusion: The CON method was able to shorten the procedure time while reducing the incidence of leakage at the catheter insertion site than the CTN method, and showed similar effects in postoperative pain management.

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