Displacement of the endotracheal tube caused by change of head position in pediatric anesthesia: evaluation by fiberoptic bronchoscopy

Ideal Depth of Endotracheal Intubation at the Vocal Cord Level in Pediatric Patients Considering Racial Differences in Tracheal Length

Numerous formulas that can predict endotracheal intubation depth at the corner of the mouth or the nasal wing of patients have been reported, even though the oral and nasal cavity anatomies differ among patients. Therefore, the purpose of this study was to derive a simple and reliable formula to predict the ideal endotracheal tube insertion depth at the vocal cord level in pediatric patients. The current study was conducted as a retrospective observational study, involving 425 and 335 cardiac pediatric patients in Germany and Japan, respectively, and aimed to determine a formula for predicting tracheal length and ideal depth of endotracheal intubation at the vocal cord level in pediatric patients. The distance between the vocal cords and the carina tracheae was defined as the tracheal length, and was measured on preoperative chest radiographs obtained in the supine position. The tracheal length in cardiac pediatric patients ranged from 6 to 10% of the body height in Germany and from 7 to 11% in Japan. This study revealed racial differences in the tracheal length, that is, in the ideal depth of endotracheal intubation at the vocal cord level. This study suggests that an adequate endotracheal intubation depth can be achieved by inserting endotracheal tubes at the vocal cord level with the minimum tracheal length of each racial group in pediatric patients, for example, 6% and 7% of the body height in Europeans and Asians, respectively. If the endotracheal tube inserted with this method appears to be shallow on chest radiographs, this does not represent an increased risk of accidental extubation, due to an excessively short intubation depth, because the minimum tracheal length for each racial group is considered. That is, it is not due to the endotracheal tube insertion length, but is likely due to the tracheal length of the patient, who has a relatively long tracheal length in the racial group.

Length of the Cricoid and Trachea in Children: Predicting Intubation Depth to Prevent Subglottic Stenosis

OBJECTIVE

Define the length of the subglottis and trachea in children to predict a safe intubation depth.

METHODS

Patients <18 years undergoing rigid bronchoscopy from 2013 to 2020 were included. The carina and inferior borders of the cricoid and true vocal folds were marked on a bronchoscope and distances were measured. Patient age, weight, height, and chest height were recorded. Four styles of cuffed pediatric endotracheal tubes (ETT) were measured and potential positions of each cuff and tip were calculated within each trachea using five depth of intubation scenarios. Multivariate linear regression was performed to identify predictors of subglottic and tracheal length.

RESULTS

Measurements were obtained from 210 children (141 male, 69 female), mean (SD) age 3.21 (3.66) years. Patient height was the best predictor of subglottic length (R² : 0.418): Length_sg (mm) = 0.058 * height (cm) + 2.8, and tracheal length (R² : 0.733): Length_t (mm) = 0.485 * height (cm) + 21.3. None of the depth of intubation scenarios maintained a cuff-free subglottis for all ETT styles investigated. A formula for depth of intubation: Length_di (mm) = 0.06 * height (cm) + 8.8 found that no ETT cuffs would be in the subglottis and all tips would be above the carina.

CONCLUSION

Current strategies for determining appropriate depth of intubation pose a high risk of subglottic ETT cuff placement. Placing the inferior border of the vocal cords 0.06 * height (cm) + 8.8 from the superior border of the inflated ETT cuff may prevent subglottic cuff placement and endobronchial intubation.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Point of care airway ultrasound to select tracheal tube and determine insertion depth in cleft repair surgery

We aimed to evaluate the efficacy of using airway ultrasonography to select the correct tracheal tube size and insertion depth in pediatric patients who underwent cleft repair surgery as a way to decrease airway complications and adverse events during perioperative periods. Fifty-one patients (age < 28 months) were consecutively divided into conventional (n = 28) and ultrasound (n = 23) groups. Tracheal tube size and insertion depth were determined using the age-based formula and auscultation in the conventional group, whereas using ultrasonographic measurement of subglottic diameter with auscultation and lung ultrasonography in the ultrasound group. We evaluated the initially selected tube size, insertion depth, ventilatory indices, and the incidence of airway complications and adverse events. Tube insertion depth (median [interquartile range]) was significantly greater in the ultrasound group than in the conventional group (13.5 cm [12.5-14.0] vs 13.0 cm [11.8-13.0], P = 0.045). The number of complications and adverse events was significantly higher in the conventional group than in the ultrasound group (32.1% vs 4.3%, P = 0.013). Airway ultrasound application could reduce airway-related complications and adverse events by determining the appropriate tracheal tube size and insertion depth.

The lengths of trachea and main bronchus in Chinese Shanghai population

The knowledge of airway length is the theoretical basis in the diagnosis and management of airway disease. The objective of this study is to measure the length of trachea and left and right main bronchus in Chinese Shanghai population. A total of 153 consecutive adult patients with minor pulmonary disease in Xinhua hospital were enrolled for bronchoscopy examination. Measurements were conducted on head and neck neutral position and height, weight and age for each patient were recorded either. Student t test and multiple linear regression was used to compare means between males and females and to analyze correlation among height, weight, sexual dimorphism and the lengths of the trachea and bronchus. The lengths of the trachea and left main bronchus are significantly different between male and female patients (P < 0.01), but not for the lengths of right main bronchus between man and woman. Multiple linear regression analysis showed that height but not sexual dimorphism and weight correlated with the lengths of the trachea and right main bronchus. The lengths of the trachea and left main bronchus are significantly longer in males than in females. Moreover, height but not sexual dimorphism and weight influenced the length of airway.

Effects of Passive Head-and-Neck Movements on the Performance of i-gel® Supraglottic Airway Device in Anesthetized Patients - A Randomized Crossover Trial

Background:

Passive movements of head and neck are sometimes unavoidable during surgery under general anesthesia due to patient positioning according to the needs of the surgery or transmitted movements from surgical manipulations.

Aims:

This prospective crossover randomized study evaluates the effects of passive movements of the head and neck on the performance of i-gel^® supraglottic airway device in spontaneously breathing patients under general anesthesia.

Materials and Methods:

Sixty spontaneously breathing patients on pressure support ventilation with positive end-expiratory pressure (PEEP) under general anesthesia were randomized to seven sequences of passive head-and-neck movements with i-gel® in situ. After steady state of general anesthesia was achieved and maintenance with sevoflurane in N₂O and O₂ was reached, the passive head-and-neck movements were done. Peak airway pressure, exhaled minute volume, end-tidal carbon dioxide (ETCO₂), oxygen saturation, audible leak of airway gases, and visible outward displacement of the i-gel® were recorded in the neutral position and with each passive head-and-neck movement. Paired continuous data were analyzed by Friedman rank sum test with paired Wilcoxon signed-rank test. Paired nominal data were analyzed by Cochran's Q test with pair-wise McNemar test.

Results:

Extension, right or left lateral flexion, and right or left rotation of the head and neck resulted in significant reduction in the exhaled minute ventilation, rise in ETCO₂, and leak of airway gases compared to the neutral position (P < 0.05). Flexion movement did not cause significant changes in the exhaled minute ventilation, rise in ETCO₂, and audible leak of airway gases as compared to the neutral position.

Conclusions:

Ventilatory performance of the i-gel® deteriorates upon extension, right or left lateral flexion, and right or left rotation of the head and neck in spontaneously breathing patients under general anesthesia on pressure support ventilation with PEEP.

Relationship Between Evaluations of Tracheal Tube Position Using Ultrasound and Fluoroscopy in an Infant and Pediatric Population

Introduction: A non-radiographic technique to measure the location of the tracheal tube (TT) in children is of value given the risk of inappropriate TT placement along with concerns about radiation exposure. Airway point-of-care ultrasound (POCUS) has demonstrated utility in children, but the examinations vary by age and may require non-traditional techniques or utilize less common probes. This study evaluated the performance of measuring the tracheal location of the cuffed TT using a novel, linear probe-based POCUS examination over a wide age range of children. After adjusting for the subjects’ height and TT size, ultrasound measurements of the TT cuff location were compared with fluoroscopy measurements of the TT tip location. Methods: Perioperative pediatric patients (<10 years) requiring a cuffed TT were enrolled. After routine TT placement, ultrasound and fluoroscopy images were obtained. Measurements from the TT cuff to the cricoid cartilage were obtained from the POCUS examination. Chest fluoroscopy was reviewed to measure the TT’s distance from the carina. Both measurements were then compared after scaling for patient height. The duration of the ultrasound examination and image quality scores were also recorded. Results: Forty-one patients were enrolled, with a median age of 3 (25th/75th percentile: 1.50/7.00) years. The POCUS examination identified the TT cuff in all cases with the highest image quality score. The median POCUS exam time was 112 (25th/75th percentile: 80.00/156.00) seconds. There was a strong correlation between the POCUS measurements and the fluoroscopy measurements, r = −0.7575, 95% CI [−0.8638, −0.5866 ], p < 0.001). Conclusions: Our results demonstrate a strong correlation between POCUS TT localization measurements and traditional measurements via fluoroscopy. This study further supports the utility of POCUS for pediatric care.

Clinical Implications of Vocal Cord-Carina Distance and Tracheal Length in the Indian Population

Objective

Securing the tracheal tube (TT) at a fixed recommended depth of 21/23 cm in female and male patients, respectively, may result in inappropriate placement of the TT in some patients. The aim of the present study was to determine the vocal cord-carina distance (VCD) and tracheal length (TL) to ascertain the optimal depth of TT placement during orotracheal intubation in the adult Indian population.

Methods

A total of 92 adults undergoing elective surgery under general anaesthesia with orotracheal intubation were studied. Surface anatomy airway measurements were noted. A cuffed TT (female size 7 mm ID and male size 8 mm ID) was inserted with the intubation guide mark at level with the vocal cords (VCs). Fiberoptic bronchoscopy-guided measurements were obtained for VCD, TL, TT tip-carina distance, VC-cricoid distance and lip-carina (L-C) distance.

Results

The mean±SD VCD was 12.82±2.05 and 12.02±1.44 cm, and TL was 10.14±2.04 and 9.37±1.28 cm in male and female patients, respectively. Statistically significant differences were observed between male and female patients in VCD (p=0.033), TL (p=0.032), L-C distance (p<0.001) and lip-TT tip distance (p<0.001); lip-TT tip distance was 19.50±1.39 cm in male patients and 18.17±1.28 cm in female patients. The L-C distance correlated with patient height, weight and neck length. L-C distance=7.214+0.049×Height+0.320×Neck length+0.033×Weight.

Conclusion

We recommend placing the TT with its proximal guide mark at the level of VCs in the Indian population. The 21/23 cm rule for tube placement depth in female and male patients, respectively, cannot be routinely followed in the Indian population.

Changes in nasotracheal tube depth in response to head and neck movement in children

BACKGROUND

A tracheal tube is often inserted via the nasal cavity for dental surgery. The position of the tube tip is important, given that the head position sometimes changes during surgery. Head movement induces changes in the length of the trachea (t-length) and/or the distance between the nare and the vocal cords (n-v-distance). In this study, we investigated the changes in t-length and n-v-distance in children undergoing nasotracheal intubation.

METHODS

Eighty patients aged 2-8 year undergoing dental surgery were enrolled. After nasotracheal intubation with an uncuffed nasotracheal tube (4.5-6.0 mm), the tube was fixed at the patient's nares. The distance between the tube tip and the first carina was measured using a fibrescope with the angle between the Frankfort plane and horizontal plane set at 110°. The location of the tube in relation to the vocal cords was then checked. These measurements were repeated at angles of 80° (flexion) and 130° (extension). The t-length and n-v-distance were then calculated using these measurements.

RESULTS

On flexion, the t-length shortened significantly from 87.5 ± 10.4 mm to 82.9 ± 10.7 mm (P = 0.017) and the n-v-distance decreased from 128.1 ± 10.7 mm to 125.6 ± 10.4 mm (P = 0.294). On extension, the t-length increased significantly from 87.5 ± 10.4 mm to 92.7 ± 10.1 mm (P = 0.007) and the n-v-distance increased from 128.1 ± 10.7 mm to 129.4 ± 10.7 mm (P = 0.729). The change in t-length was significantly greater than that in the n-v-distance.

CONCLUSION

A change in the position of the tracheal tube tip in the trachea depends mainly on changes in t-length during paediatric dental surgery.

Estimation of optimal nasotracheal tube depth in adult patients

Background

The aim of this study was to estimate the optimal depth of nasotracheal tube placement.

Methods

We enrolled 110 patients scheduled to undergo oral and maxillofacial surgery, requiring nasotracheal intubation. After intubation, the depth of tube insertion was measured. The neck circumference and distances from nares to tragus, tragus to angle of the mandible, and angle of the mandible to sternal notch were measured. To estimate optimal tube depth, correlation and regression analyses were performed using clinical and anthropometric parameters.

Results

The mean tube depth was 28.9 ± 1.3 cm in men (n = 62), and 26.6 ± 1.5 cm in women (n = 48). Tube depth significantly correlated with height (r = 0.735, P < 0.001). Distances from nares to tragus, tragus to angle of the mandible, and angle of the mandible to sternal notch correlated with depth of the endotracheal tube (r = 0.363, r = 0.362, and r = 0.546, P < 0.05). The tube depth also correlated with the sum of these distances (r = 0.646, P < 0.001). We devised the following formula for estimating tube depth: 19.856 + 0.267 × sum of the three distances (R² = 0.432, P < 0.001).

Conclusion

The optimal tube depth for nasotracheally intubated adult patients correlated with height and sum of the distances from nares to tragus, tragus to angle of the mandible, and angle of the mandible to sternal notch. The proposed equation would be a useful guide to determine optimal nasotracheal tube placement.

Patient-specific depth of endotracheal intubation-from anthropometry to the Touch and Read Method

Objective:

Knowledge of accurate airway length (AL) enables safer placement of the endotracheal tube (ETT) in the trachea. Our objective was to check the safety of a new formula (Touch and Read method) to determine ETT depth.

Methods:

AL was measured in 176 patients. Patients were divided into a normal group (AL >25 cm in men, >23 cm in women) and a risk group (AL ≤25 cm in men, ≤23cm in women). A control test (Conventional method) was performed in which the ETT was secured at a depth of 23 cm from the central incisor in men and 21 cm in women. In the experimental test (Touch and Read method), the ETT was secured at a depth equal to the distance from the angle of the mouth to the epiglottis tip plus 12.5 cm in men and 11.5 cm in women. The mean distance from the tube tip to the carina and that from the vocal cords to tube cuff were compared between the control and experimental tests in each group.

Results:

The two distances were similar between control and experimental tests in the normal group, but differed in the risk group (Women: mean distance from tube tip to carina, 1.2 cm and from vocal cords to cuff, 2.7 cm [control test]; 1.9 and 2.0 cm, respectively [experimental test]. Men: 0.7 and 3.5 cm, respectively [control test]; 2.0 and 2.3 cm, respectively [experimental test]).

Conclusion:

Touch and Read method enables safer placement of the ETT in the trachea than the conventional method in the risk group.

Bedside prediction of airway length by measuring upper incisor manubrio-sternal joint length

BACKGROUND

Malpositioning of endotracheal tube may lead to serious complications like endobronchial intubation or accidental extubation. Using anatomical measurements for prediction of airway length would be more practical in resource constrained settings.

MATERIALS AND METHODS

One hundred adult patients of American Society of Anesthesiologists (ASA) grade 1 or 2, without any evidence of difficult airway, were randomly allocated to two cohorts - a model cohort of 70 (50 males) and test cohort of 30 (20 males) subjects. Height, the straight length from the upper incisor to manubrio-sternal joint in fully extended head position (IncManustL), the length from upper incisor to the carina in neutral head position (IncCarinaL), and degree of neck extension were measured in all subjects. Relationship between the two lengths in the model cohort was explored by Pearson's coefficient (r). Predictions were made for subjects in the test cohort and actual and predicted values assessed for agreement using intra-class correlation coefficient (ICC).

RESULTS

Good agreement was found between IncManustL and IncCarinaL for both male (r = 0.69) and female (r = 0.54) subjects. Multiple regression analysis suggested height to be another significant predictor, unlike age, weight, and neck extension. The gender-specific regression equations were used to predict IncCarinaL for the test cohort. ICC for absolute agreement between the actual and predicted values was 0.723 (95% CI 0.495-0.858).

CONCLUSIONS

It is possible to predict airway length in adult Indian subjects by making two simple anatomical measurements, namely stature and incisor manubrio-sternal joint length.

Influence of head flexion after endotracheal intubation on intraocular pressure and cardio-respiratory response in patients undergoing cataract surgery

BACKGROUND

During preparation and draping of periorbital area, neck flexion causes displacement of the endotracheal tube tip toward the carina. Stimulation of the tracheal mucosa may cause bucking, increased intraocular pressure (IOP), laryngospasm, bronchospasm, change in end-tidal carbon dioxide pressure (PETCO2) or peripheral arterial haemoglobin oxygen saturation (SpaO2) during light anaesthesia.

OBJECTIVE

To investigate the influence of head and neck flexion after endotracheal intubation on heart rate (HR), systolic and diastolic blood pressure (SAP and DAP), SpaO2, PETCO2 and IOP in patients undergoing cataract surgery during general anesthesia.

METHOD

In this prospective observational study, 106 ASA physical status I and II patients scheduled for elective cataract surgery under general anaesthesia were studied. Anaesthesia was induced with thiopental sodium, lidocaine and fentanyl. Atracurium 0.5 mg/kg was given to facilitate tracheal intubation. HR, SAP, DAP, SpaO2, PETCO2, and IOP were measured at 1, 2, and 5 minutes after head flexion.

RESULTS

Mean SAP, DAP, IOP, and HR were significantly increased after head flexion compared with baseline values (P < 0.05). PETCO2 and SpaO2 were significantly decreased at 1 and 2 minutes after head flexion compared with baseline values (P < 0.001).

CONCLUSION

It is concluded that endotracheal tube movement by changes in head and neck position has significant effects on heart rate, systolic and diastolic blood pressures, laryngeal reflexes, SpaO2, PETCO2, and intraocular pressure in patients undergoing cataract surgery under general anaesthesia.

Tracheal tube tip displacement during laparoscopy in children

The risk of endobronchial intubation during laparoscopy because of displacement of the tip of the tracheal tube is a well known problem in adults. Laparoscopy in children is increasingly performed, but there are no data available regarding the above problem. We prospectively studied 46 children aged 2 months to 15.7 years (median 4.2 years) undergoing laparoscopy. After tracheal intubation with the Microcuff Pediatric Endotracheal Tube, with the 'intubation depth marking' of the tube at the vocal cords, the distance from the tracheal tube tip to the carina was endoscopically measured with the patient in the neutral position and with 20 degrees head-down tilt, both with and without capnoperitoneum. Maximal displacement of the tip of the tracheal tube tip in cm was 0.5+(0.05xage (years)) for 20 degrees head-down tilt, 0.6+(0.09xage (years)) for capnoperitoneum alone, and 1.2+(0.11xage (years)) for 20 degrees head-down tilt with capnoperitoneum. In no patients did endobronchial intubation occur with the tracheal tube placed according to the intubation depth marking.

Characteristics and outcome of unplanned extubation in ventilated preterm and term newborns on a neonatal intensive care unit

BACKGROUND

Unplanned extubation events (UEE) are a serious hazard to patient safety, especially on a neonatal intensive care unit (NICU), where reestablishing a secure airway can be difficult. The following study was undertaken to analyze characteristics of UEE and develop prevention strategies.

METHODS

A retrospective cohort study on a level III single center NICU was undertaken. Patient records of a 12-month period from December 2003 to December 2004 were analyzed using a standardized evaluation form. Fischer's exact t-test and the Mann-Whitney U-Ranked Sum test were used for statistical analysis.

RESULTS

One hundred and four neonates with a total ventilation time of 14 495 h were included in this study. Of these patients 12 UEE were observed (1 UEE/1208 h of ventilation time). Neither median birth weight [1445 g (range 460-4650) vs 1755 g (range 460-3570 g)] nor median gestational age [31.5 weeks (range 25.6-39.6 weeks) vs 32.7 weeks (range 23.9-41.5 weeks)] differed significantly between neonates with UEE compared with the total group. When the UEE occurred, the neonates were cared for by experienced nursing staff with a median of 10 years nursing experience. The workload for the individual nurse was high: during shifts when UEE happened, each nurse had to take care of 3.85 patients (range 1.8-5 patients). This workload was higher than the average of 3 (range 1.6-6) patients/nurse during the study period. The most frequently reported reason for UEE was difficult fixation of the tracheal tube (TT) (four patients), followed by handling of the infant by nursing staff or physiotherapy (two patients) or an active infant in whom dislocation of the TT occurred without external manipulations (three patients). In three instances, the reason for the UEE was not documented. Of the 12 UEE observed in 10 patients, three required immediate reintubation, five were managed with nasal continuous positive airway pressure and four did not require further respiratory support. Of those who required support, FiO(2) increased by 14% over baseline compared with the FiO(2) prior to UEE.

CONCLUSIONS

Inadequate TT fixation could be identified as the main contributor to UEE and should be targeted in prevention strategies. The reintubation rate after UEE was only 25%. Overall, UEE did not result in an adverse outcome in terms of mortality. Length of stay on NICU was significantly longer in UEE patients.