Accuracy of Age-Based Formula to Predict the Size and Depth of Cuffed Oral Preformed Endotracheal Tubes in Children Undergoing Tonsillectomy

Objectives: To retrospectively investigate the reliability of the age-based formula, year/4 + 3.5 mm in predicting size and year/2 + 12 cm in predicting insertion depth of preformed endotracheal tubes in children and correlate these data with the body mass index. Patients and Methods: Patients were classified into 4 groups according to their nutritional status: thinness, normal weight, overweight, and obesity; we then retrospectively compared the actual size of endotracheal tube and insertion depth to the predicting age-based formula and to the respective bend-to-tip distance of the used preformed tubes. Results: Altogether, 300 patients were included. The actual endotracheal tube size corresponded with the Motoyama formula (64.7%, 90% CI: 60.0-69.1), except for thin patients, where the calculated size was too large (0.5 mm). The insertion depth could be predicted within the range of the bend-to-tip distance and age-based formula in 85.0% (90% CI: 81.3-88.0) of patients. Conclusion: Prediction of the size of cuffed preformed endotracheal tubes using the formula of Motoyama was accurate in most patients, except in thin patients (body mass index < −2 SD). The insertion depth of the tubes was mostly in the range of the age-based-formula to the bend-to-tip distance.

Estimation of Appropriate Endotracheal Tube Size in Pediatric Patients: Use of Epiphyseal Diameter of the Distal Radius and Subglottic Diameter

INTRODUCTION: The aim of this study is to test the usefulness of epiphysis of distal radius measurement as a surrogate parameter for endotracheal tube (ETT) size prediction in children. METHODS: Seventy-three children were intubated with cuffed ETT selected according to age-based formula. Transvers diameter of epiphysis of distal radius and subglottic diameter of trachea were measured by ultrasound (US). Correlation between the outer diameter of best-fit endotracheal tube and transvers diameter of both radius epiphysis and subglottic diameter were calculated. The need for tube exchange, time for ultrasound (US) measurements and the ease level of measurements were compared. RESULTS: First attempt success at intubation was 83.6%. The correlation of the epiphysis diameter of the distal radius and best-fit ETT was significant (p<0.001, r= 0.619, r2=0.383, 95% CI=0.419-0.838). Similarly the correlation of subglottic tracheal diameter and best-fit ETT was significant (p<0.001, r=0.744, r2=0.553, 95% CI=0.678-825). Estimated ETT sizes according to radial epiphysis diameter and subglottic diameter were optimal in 82.2% and 94.5% respectively. Time for the US measurements of radial epiphysis and subglottic area were 38.3±9.6 and 24.9±4.6 seconds respectively (p<0.001). The level of ease of US measurements were rated for radial epiphysis as 6 (5-9) and for subglottic area as 8 (7-9) (p<0.001). DISCUSSION AND CONCLUSION: US measured transverse diameter of distal radius epiphysis resulted in similar success rate to age-based formula in our child population. Subglottic diameter measured by US estimates ETT size more accurately; it is also less time consuming and easier.

Perioperative Point-of-Care Ultrasound in Children

Anesthesiologists and other acute care physicians perform and interpret portable ultrasonography—point-of-care ultrasound (POCUS)—at a child’s bedside, in the perioperative period. In addition to the established procedural use for central line and nerve block placement, POCUS is being used to guide critical clinical decisions in real-time. Diagnostic point-of-care applications most relevant to the pediatric anesthesiologist include lung ultrasound for assessment of endotracheal tube size and position, pneumothorax, pleural effusion, pneumonia, and atelectasis; cardiac ultrasound for global cardiac function and hydration status, and gastric ultrasound for aspiration risk stratification. This article reviews and discusses select literature regarding the use of various applications of point-of-care ultrasonography in the perioperative period.