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Accuracy of a new body length-based formula for predicting tracheal tube size in Chinese children

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Variations in body weight and length (height) in children in the same age group have increased. Traditional age-based formulas often fail to predict the correct endotracheal tube (ETT) size. In our previous study, we devised a new length-based formula as follows: ETT internal diameter (ID) (mm) = 2 + (body length in cm/30). The current study was undertaken to assess the accuracy of this formula in Chinese children. The ETT size was selected according to this length-based formula for 336 children who required tracheal intubation during general anesthesia. Incidences of tube change were recorded. Statistical analysis was performed using the chi-square test for differences in accuracy between age groups and body length groups. The length-based formula predicted a suitable ETT size in 277 (82.4%) of 336 subjects. There were 59 (17.6%) reintubations. Only 5 (1.49%) patients needed two tube changes when the correct ETT size was 1 mm larger or smaller than predicted. There were no statistically significant differences between age groups or length groups. The length-based formula ID (mm) = 2 + body length in cm/30 has high accuracy in predicting the appropriate ETT size in Chinese children.
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... Selecting the appropriate tracheal tube size is important for airway managements. Several methods were reported to decide the proper size (ID: internal diameter) of an orotracheal tube [5][6][7][8]. In the case of orotracheal intubation, there are main available formulas based on weight (ID = weight [kg]/10 + 3.5), age (ID = 4 + age [years]/4), and height (ID = 2+ height [cm]/30), and they should be applicable for nasotracheal intubation [5][6][7][8][9][10][11]. ...
... Several methods were reported to decide the proper size (ID: internal diameter) of an orotracheal tube [5][6][7][8]. In the case of orotracheal intubation, there are main available formulas based on weight (ID = weight [kg]/10 + 3.5), age (ID = 4 + age [years]/4), and height (ID = 2+ height [cm]/30), and they should be applicable for nasotracheal intubation [5][6][7][8][9][10][11]. ...
... Anesthesiologists should select a tube size for nasotracheal intubation to maintain sufficient ventilation, but not too large for nasal cavity. Larger tube might cause ischemic injury and result in mucosal damage including the vocal cord and the subglottic structures, while a too small sized tracheal tube might create large air leaks resulting in inadequate oxygenation and ventilation [4,7,8,12]. ...
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Objectives Developmental disability children have differences in growth. Therefore, tube size selection is important for nasotracheal intubation. In our previous study for healthy children undergoing dental surgery, height was the most suitable factor to predict nasotracheal tube size. The aim of this study was to find the most suitable formula for selection of nasotracheal tube size for them, retrospectively.Material and methodsDevelopmental disability children aged 2 to 10 years were included in this study. They were intubated nasotracheally from April 2012 until May 2017. Their actually intubated tube sizes were checked. The predicted tube sizes were calculated according to the formulas by the backgrounds: the diameter of the trachea at the 6th cervical (C6), 7th cervical (C7), and 2nd thoracic vertebrae (T2) in X-ray. The actually intubated tube sizes were compared with predicted sizes. Data were analyzed using Spearman’s regression analysis.ResultsThe tube sizes with 5.0, 5.5, and 6.0 mm ID were intubated in 75 patients. The age-based formula was the most suitable; the correlation coefficients (r2) were 0.9027 (vs age), 0.5434 (vs height), 0.3779 (vs weight), 0.0785 (vs C6), 0.2279 (vs C7), and 0.3065 (Th2) (p < 0.01). However, 0.5-mm smaller size tubes were more frequently intubated actually. Their correspondence rate to the predicted size was 48% (5.0 mm), 52% (5.5 mm), and 39% (6.0 mm), respectively.Conclusion The age-based formula could be the most suitable for predicting nasotracheal tube size in developmental disability children aged 2 to 10 years. One smaller size by the age formula was most suitable at first trial tube.Clinical relevanceThe present data indicate that the selection of nasotracheal tube using one smaller size by the age formula (ID = 4 + age [years]/4) might be useful for developmental disability children.
... [4,11] Prediction of TT size based on length varies from 55% in European children using Broselow tape, [12] to 82% in Chinese children using the formula ID = 2 + (height in cm/30). [13] Body weight has also been used occasionally to predict the size of TT [14] but has low accuracy (45%). [5] The primary aim of the present study was to prospectively evaluate age, length and weight as predictors for the size of uncuffed TT in Indian children. ...
... The accuracy was much less when older children aged 2-10 years (55%-60%) were studied. [4,13] Our formula (PTSP) was also more accurate in children in the age group of 1-4 years (~90%) than in children older than 4 years (50%). Thus LBFs seem to be more accurate in young children up to the age of 4-6 years. ...
... There appears to be some effect of ethnicity too on the accuracy of the standard LBF. It was derived in Chinese children and was more accurate in Asian (Chinese 82%, [13] Korean 87%, [19] and Indian 67% [present study]) than Caucasian children (55%). [12] This effect may be due to the difference in anthropometric measurements of the children based on their ethnicity. ...
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Background and aims: The accuracy of age-, length- and weight-based formulae to predict optimal size of uncuffed tracheal tubes (TTs) in children varies widely. We determined the accuracy of age, length and weight in predicting the size of TT in Indian children, and derived and validated a formula using the best predictor. Methods: In the derivation phase, 100 children aged 1-8 years undergoing general anaesthesia and tracheal intubation with an uncuffed tube were prospectively studied. The correct size of the TT used was confirmed using the leak test. A bootstrap resampling procedure was used to estimate the accuracy of the predictors (age, weight, or length alone; length and age; length and weight; and length, weight and age). The best predictor was used to derive a formula (Paediatric Tube Size Predictor, PTSP) to calculate the size of TT. The accuracy of PTSP was tested in 150 children of the same age group in the validation phase. Results: Length (L (in meters), R2 = 0.61) was the best single predictor of the size of TT and was used to derive the PTSP as internal diameter = 3L + 2.5. In the validation phase, the PTSP predicted the size of TT correctly in 75% of children. Re-intubation was associated with a higher incidence of respiratory morbidity than one-time tracheal intubation. Conclusion: Length of the child predicts the size of an uncuffed TT better than age and weight. The PTSP formula based on length correctly predicts the size of uncuffed TT in 75% of children.
... With the exception of premature gestation-based recommendations, 4 current age-based formulae have long been recognized as inadequate. Newer weight, 5 length, 6 and anthropomorphic alternatives, such us foot length, 7 middle finger length, 8 and tragus to nares length, 9 have all been studied and found to be better alternatives for infants. Many of these studies were retrospective, and almost all excluded any significant anomalies and pathology. ...
... These investigators have conducted one of the few prospective cohort studies evaluating patients who have a coronary artery stent and subsequently undergo noncardiac surgery. 6 They performed perioperative platelet function testing using a Platelet Mapping Assay (PMA) to test their hypothesis that adequate platelet inhibition would reduce the incidence of the primary outcome of major adverse cardiac events (i.e. MI, congestive heart failure, in-stent thrombosis, coronary revascularization, or death) within 30 days after noncardiac surgery. ...
... [3] Whereas smaller tube there will be increased gas flow resistance, aspiration risk, poor ventilation, inaccurate monitoring of end tidal gases and reintubation may also be required with a different size of tracheal tube. [4] Different physical indices formulas used for prediction of endotracheal tube size are age based formula (Age + 16)/4, [5] body length based formula [2 + length (in cms)/30], [6] multivariate Formula (2.44 + age in year × 0.1 + height in cm × 0.02 + weigh in kg × 0.016.), [7] diameter of fifth right and left finger [8] which is measured as anterior to posterior diameter of the distal digit with the caliper to the nearest 0.1 mm. ...
Article
Background Paediatric airway assessment remains the most challenging task before the anaesthesiologists. Recent advancement in ultrasonography techniques should now allow for accurate and descriptive evaluation of paediatric airway. To compare calculated external diameters of the endotracheal tube from physical indices of traditional formulas and predetermined by ultrasound. Materials and Methods 100 subjects of either sex between 12-60 months of age, undergoing various elective surgeries under general anaesthesia requiring endotracheal intubation were enrolled in the study. The transverse diameter was measured at the level of cricoids cartilage by ultrasonography. The tracheal tube was considered best fit if air leak was satisfactory at 15-20 cm H2O of airway pressure. The obtained values were compared with the values of endotracheal tube size calculated by various age, height, weight based formulas and diameter of right and left little finger. The correlation of size of Endotracheal tube by different modalities was done and Pearson's correlation coefficient was obtained. Results According to Pearson's correlation there was a moderate correlation of best fit Endotracheal tube with endotracheal tube size by age based formula (r = 0.743), body length based formula (r = 0.683), right little finger based formula (r = 0.587), left little finger based formula (r = 0.587) and multivariate formula (r = 0.741). There was a strong correlation with ultrasonography (r = 0.943). Conclusion Ultrasonography is a reliable method of estimation of subglottic diameter and for prediction of endotracheal tube size in children.
Article
Background: Providing safe anaesthesia to paediatric patients is a challenging task. This requires a thorough knowledge of the soft and pliable paediatric airway. Owing to the vulnerability of the anatomical structures involved, choosing an appropiate sized endotracheal tube (ETT) is important in these cases. A larger sized ETT may lead to trauma and a smaller one would result in leakage and risk of aspiration. Both situations demand an immediate tube change, thereby complicating the condition. The physical indices- based formulae have often failed to justify the purpose leading to repeated laryngoscopy and tube change during intubation. The increase in availability of the modern ultrasound devices have shown promise in these cases. Aims and objectives: In this study we examine the accuracy of ultrasonography (USG)to assess the appropriate ETT size, comparing it with physical indices based formulae suggested ETT size so that repeated attempts on intubation can be minimized. Materials and methods: The study group included 100 patients of 1-5 years, ASA I- II, requiring orotracheal intubation under general anaesthesia. The tracheal sub-glottic diameter was estimated by pre-anaesthetic USG to determine the ETT size, both cuffed and uncuffed. ETT data obtained by these methods were compared by Pearson's correlation coefficient and t-test. Results: USG predicted ETT size were significantly more consistent than the physical indices based formulae. Also the age based formulae were found to be more precise than the height based ones. Seven patients required change of tube once. Conclusion: Ultrasonography is an effective tool in predicting paediatric ETT size.
Article
Background The common method for estimating uncuffed tracheal tube (TT) size is using the physically-based formula. However, it's limited by physical differences due to geographical variations. This study aims to compare the accuracy of the uncuffed TT size estimation using the body length formula, the left-hand 5th fingernail width, and the ultrasonographic method in Indonesian pediatric patients. Methods This study was a comparative observational study on 40 pediatric patients. The estimation of the precise uncuffed TT size done using the body length formula (Group K, n = 14), the left-hand 5th fingernail width method (group L, n = 13), and the ultrasonographic method (group M, n = 13) to measure the subglottic area. The accuracy of the TT size selection was recorded and statistically analyzed using the T-test and Odd Ratio test using SPSS 19.0 software. Result The highest uncuffed TT size accuracy was found in the ultrasonographic method (92%), while the lowest was found in body length formula (64%). The ultrasonography tends to estimate the precise TT size seven times higher than the body length formula and five times higher than the Left-hand 5th fingernail width. Conclusion The ultrasonographic method can estimate the precise uncuffed TT size with high accuracy and can be used as the uncuffed TT size estimation method in Indonesian pediatric patients.
Introduction The age-based formula is commonly used to predict tracheal tube (TT) sizes although its inaccuracy has been reported to reach as high as 60%. We aim to determine a practical formula using age in months and weight in kilograms to predict uncuffed tracheal tube (TT) size in children and infants. Methods A retrospective cross-sectional study was conducted on data obtained from a prospective study on children aged less than 9 years who came for elective surgery and received general anesthesia with oroendotracheal tube intubation at Songklanagarind Hospital between September 2008 and December 2012. The uncuffed TT sizes were based on the age-based formulae and the discretion of the attending anesthesiologist. The age (in months), weight (in kg), and final TT size were measured. Univariate and multivariate linear regression analyses were used to find potential predictors of final uncuffed TT size and therefore the best formula. The correlation coefficient (r) for each model was calculated. The kappa statistic was used to measure the agreement between predicted and actual TT size. Results A total of 668 patients were recruited. The age/weight formulae for infants aged ≤12 months and children aged >12 months were 3.15 + (age [months] × 0.05) + (weight [kg] × 0.05) with r value of 0.75 (n = 216) and 3.83 + (age [months] × 0.017) + (weight [kg] × 0.017) with r value of 0.85 (n = 452), respectively. The formulae correctly predicted 69.0% and 65.0% of actual TT sizes for infants and children, respectively (both p < 0.001). The formulae for malnourished infants and children whose weights were less than the 3rd percentile for age were 2.70 + (weight [kg] × 0.21) (n = 43) and 3.59 + (age [months] × 0.012) + (weight [kg] × 0.056) (n = 105) with r values of 0.81 and 0.87, respectively. Conclusion The age/weight formula can be used to estimate TT size in infants and children. In failure to thrive children, our formula for malnourished children and infants provided high correlation with final TT sizes.
Article
Objectives The selection of an appropriate size of tracheal tube is important for airway management. For nasotracheal intubation, passing the nasal cavity should be taken into account for the selection of tube size. The aim of this study was to investigate the selection of appropriate size of nasotracheal tube in pediatric patients retrospectively. Materials and methods The 1–12-year patients underwent dental procedures under general anesthesia intubated nasotracheally. The correlation between height, age, weight, the tracheal diameters at C6, C7, Th2 on the chest X-ray, and actually performed tube sizes were calculated. In addition, we compared the relationships between the predicted tube size and actually the intubated tube size. Results The tube sizes intubated actually were between 4.0 and 6.0-mm ID. The formula by height could be most suitable for tube size. The correspondence rates for the tube with 4.5- and 5.0-mm ID were 78% and 53%. When they were predicted as 5.5- or 6.0-mm ID, 0.5 mm smaller size tube were intubated actually; 56% and 70%. When the predicted tube size was 4.0-mm ID, 0.5 mm larger size tube was intubated actually; 66%. Conclusions The formula by height could be most suitable for the selection of size for pediatric nasotracheal intubation. When the predicted tube size was 5.5 or 6.0-mm ID, 0.5 mm smaller size should be chosen at first. In the case of 4.0-mm ID, 0.5 mm larger size should be chosen for first trial. Clinical relevance The present data indicate that the selection of nasotracheal tube using the formula by height might be useful.
Article
Background and Aims Several formulae are available to estimate endotracheal tube (ETT) size in children. This study was designed to compare the ETT estimated by the Broselow tape (BT) with age-based estimation of ETT size and to identify the most accurate formula for the prediction of uncuffed ETT size in Indian children. Material and Methods Pediatric patients aged 1 month–6.5 years undergoing emergency or elective surgery under general anesthesia requiring endotracheal intubation with uncuffed ETT were included in this study. The ETT size was selected based on the age formula (Penlington formula). The ETT used was deemed to be of correct fit based on the delivery of adequate tidal volume and presence of minimal leak at 20 cm H2O. The actual ETT used was compared with that predicted by age, length of the child, BT, and fifth fingernail width of the child using Pearson's correlation. Results In children aged <6 months, the ETT used was found to correlate with length (r = 0.286, P = 0.044) and finger nail width (r = 0.542, P < 0.001) of the children. In children >6 months, the ETT used correlated with that predicted from age, BT, length, and fingernail width of the children. In our study, BT has an overall correct predictability rate of 50.3% whereas the age-based formula has a correct prediction rate of 59.8% and length-based formula is 48.7% accurate. Conclusion Length of the child has a good correlation with size of the ETT to be used in Indian children across all age groups. BT is an effective tool to predict ETT size in children >6 months.
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Introduction: Choosing the correct Endotracheal Tube (ETT) size is important in paediatric anaesthesia. The subglottic diameter being the narrowest diameter of the paediatric upper airway plays an important role in appropriate ETT size selection. Aim: This study was planned to determine the accuracy of Ultrasonography (USG) to assess the appropriate ETT size and compare it with physical indices based formulae. The secondary outcome was to assess the number of times the tube was changed based on air leak test for USG estimated tube size. Materials and Methods: After ethical committee approval, a prospective clinical observational study for a period of one year was conducted on 75 children (power of study 80%, confidence interval 95%) aged one to 14 years of American Society of Anaesthesiologists Physical Status (ASA) I and II undergoing elective surgery under general anaesthesia with orotracheal intubation. Parental consent was obtained. Preanaesthetic ultrasonography was performed on every patient at the subglottic region. The tracheal subglottic diameter was estimated to select the ETT size for cuffed and uncuffed tubes. The size estimated by USG and that based on age and height based formulae were compared with clinically used appropriate tube size. Data analysis was done using IBM Statistical Package for the Social Sciences (SPSS) version 20.0; One-way Analysis of Variance (ANOVA) and t-test for comparison were used. Results: USG predicted the appropriate ETT size (p
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To the Editor.—We read with interest the article entitled "The Prognostic Value of Endotracheal Tube-Air Leak" by Seid et al1 that appeared in the Archives. Our experience has been that a leak around the endotracheal tube that is less than 30 cm H2O is associated with a favorable postoperative outcome; however, the formula used to calculate endotracheal tube size is (age +16)/4 in children more than 2 years of age rather than the formula that was printed (age +26)/4.2 The latter formula would indicate an unusually large endotracheal tube. We are interested in the authors' comments regarding this.
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We prospectively studied 282 consecutive tracheal intubations (243 patients) in a pediatric intensive care unit during a 7-month period to compare cuffed and uncuffed endotracheal tube (ETT) utilization and outcome. The incidence of postextubation stridor in each ETT group was the major outcome measure after controlling for various patient risk factors. Patients whose ETTs were inserted in the operating room, who were less than 1 year of age, or who had ETTs in place for less than 72 hours were more likely to have had insertion of an uncuffed ETT. Patients whose ETTs were inserted in the emergency department or who were more than 5 years of age were more likely to have had insertion of a cuffed ETT. Those who had a cuffed ETT were older (mean 8.1 vs 2.5 years) and had ETTs in place longer (mean 6.1 vs 3.7 days) than patients with an uncuffed ETT. Of the 188 patients who subsequently had removal of their ETTs, the overall incidence of postextubation stridor was 14.9%, with no significant difference between the two ETT groups even after controlling for patient age, duration of intubation, trauma, leak around ETT before extubation, and pediatric risk of mortality score. Two patients in the cuffed ETT group and four patients in the uncuffed ETT group required reintubation for severe postextubation stridor. Long-term follow-up identified 33 patients (17%) who required hospital readmission. None of these was admitted with an upper airway problem. Two patients who previously had insertion of a cuffed ETT subsequently received tracheostomies for the primary purpose of long-term mechanical ventilation unrelated to any problem with the upper airway. We conclude that cuffed endotracheal intubation is not associated with an increased risk of postextubation stridor or significant long-term sequelae.