Use of an optical fiber scope to confirm endotracheal tube placement in pediatric patients

A new formula based on height for determining endotracheal intubation depth in pediatrics: A prospective study

STUDY OBJECTIVE

The main objective was to devise an endotracheal intubation formula based on pediatric patients' strongly correlated growth parameters. The secondary objective was to compare the accuracy of the new formula to the age-based formula from Advanced Pediatric Life Support Course (APLS formula) and the middle finger length-based formula (MFL-based formula).

DESIGN

A prospective, observational study.

SETTING

Operation.

PATIENTS

111 subjects age 4-12 years old undergoing elective surgeries with general orotracheal anesthesia.

INTERVENTIONS AND MEASUREMENTS

Growth parameters, including age, gender, height, weight, BMI, middle finger length, nasal-tragus length, and sternum length, were measured before surgeries. Tracheal length and the optimal endotracheal intubation depth (D) were measured and calculated by Disposcope. Regression analysis were used to establish a new formula for predicting the intubation depth. A self-controlled paired design was used to compare the accuracy of the intubation depth between the new formula, APLS formula, and MFL-based formula.

MAIN RESULTS

Height (R = 0.897, P < 0.001) was strongly correlated to tracheal length and the endotracheal intubation depth in pediatric patients. New formulae basing on height were established, including new formula 1: D (cm) = 4 + 0.1 × Height (cm) and new formula 2: D (cm) = 3 + 0.1 × Height (cm). Via Bland-Altman analysis, the mean differences for new formula 1, new formula 2, APLS formula and MFL-based formula were - 0.354 cm (95% LOA, -1.289 to 1.998 cm), 1.354 cm (95% LOA, -0.289 to 2.998 cm), 1.154 cm (95% LOA, -1.002 to 3.311 cm), -0.619 cm (95% LOA, -2.960 to 1.723 cm), respectively. The rate of optimal intubation for new formula 1 (84.69%) was higher than for new formula 2 (55.86%), APLS formula (61.26%), and MFL-based formula. (69.37%).

CONCLUSIONS

The prediction accuracy for intubation depth of the new formula 1 was higher than the other formulae. The new formula based on height: D (cm) = 4 + 0.1 × Height (cm) was preferable to APLS formula and MFL-based formula with a high incidence of appropriate endotracheal tube position.

Predicting the risk of inappropriate depth of endotracheal intubation in pediatric patients using machine learning approaches

Endotracheal tube (ET) misplacement is common in pediatric patients, which can lead to the serious complication. It would be helpful if there is an easy-to-use tool to predict the optimal ET depth considering in each patient's characteristics. Therefore, we plan to develop a novel machine learning (ML) model to predict the appropriate ET depth in pediatric patients. This study retrospectively collected data from 1436 pediatric patients aged < 7 years who underwent chest x-ray examination in an intubated state. Patient data including age, sex, height weight, the internal diameter (ID) of the ET, and ET depth were collected from electronic medical records and chest x-ray. Among these, 1436 data were divided into training (70%, n = 1007) and testing (30%, n = 429) datasets. The training dataset was used to build the appropriate ET depth estimation model, while the test dataset was used to compare the model performance with the formula-based methods such as age-based method, height-based method and tube-ID method. The rate of inappropriate ET location was significantly lower in our ML model (17.9%) compared to formula-based methods (35.7%, 62.2%, and 46.6%). The relative risk [95% confidence interval, CI] of an inappropriate ET location compared to ML model in the age-based, height-based, and tube ID-based method were 1.99 [1.56-2.52], 3.47 [2.80-4.30], and 2.60 [2.07-3.26], respectively. In addition, compared to ML model, the relative risk of shallow intubation tended to be higher in the age-based method, whereas the risk of the deep or endobronchial intubation tended to be higher in the height-based and the tube ID-based method. The use of our ML model was able to predict optimal ET depth for pediatric patients only with basic patient information and reduce the risk of inappropriate ET placement. It will be helpful to clinicians unfamiliar with pediatric tracheal intubation to determine the appropriate ET depth.

Accuracy of predictive equations in guiding tracheal intubation depth in children: A prospective study

BACKGROUND

Accurate insertion depth of endotracheal tube (ETT) in children has been predicted using the demographic variables, such as age, weight, and height. Middle finger length showed good correlation with ETT depth measurement in children aged 4-14 years.

AIMS

The primary objective was to correlate the actual ETT insertion depth with the depth derived from middle finger length, age, weight, and height formulae in children aged 1-4 years. The secondary objective was to find the most accurate formula for prediction of ETT insertion depth.

METHODS

This prospective parallel group study was done in 50 american society of anesthesiologists 1 or 2 children aged 1-4 years undergoing elective surgery under general anesthesia. Children with difficult airway, finger anomalies, or syndromic associations were excluded. Age, weight, height, and middle finger length of all children were measured. Depth of orally inserted uncuffed ETT and tracheal length was measured by fiberoptic bronchoscopy. The actual ETT depth was correlated with the depth calculated from different formulae.

RESULTS

The mean middle finger length was 4.42 ± 0.50 cm, age was 2.64 ± 1.07 years, weight was 12.28 ± 2.84 kg, and height was 82.89 ± 16.23 cm. The mean tracheal length was 6.42 ± 0.96 cm. The mean depth of ETT was actual depth (12.89 ± 1.09 cm), middle finger depth (13.23 ± 1.53cm; p = .001; 95%CI 0.12-0.50), age-based depth 1(3.31 ± 0.53 cm; 95%CI 0.37-1.44; p = .001), weight-based depth (14.14 ± 1.42 cm; 95% CI 0.10-0.51; p = .004), and height-based depth (13.73 ± 0.94 cm; 95% CI 0.15-0.77; p = .004). Middle finger length and age-based formulae showed higher number of accurate placements (58% each). Weight- (74%) and height (64%)-derived formulae gave a higher number of distal ETT placements.

CONCLUSION

Formulas based on the demographic variables and middle finger length showed good correlation with the actual ETT depth in children aged 1-4 years. The percentage of accurate ETT depth placements was higher with middle finger length and age-based formulae.

Diagnostic utilities of tracheal ultrasound and USB-endoscope for the confirmation of endotracheal tube placement: A cadaver study

OBJECTIVES

Confirmation of the endotracheal tube placement (CoETP) has the utmost importance in the management of an airway. Visualization of tracheal rings or carina with a fiber-optical bronchoscope (FOB) has considered to be a reliable method for the CoETP. However, FOB is expensive, time-consuming, and not always practical. Inexpensive endoscopic USB-cameras were shown to aid intubation successfully and reliably. On the other hand, there have been no studies investigating their use for the CoETP. Tracheal ultrasonography (TUS) is also a new, inexpensive and widely available alternative. A cadaver study has planned to evaluate the diagnostic utility of TUS and a USB-camera.

METHODS

This study was conducted in the Anatomy Lab of a University on a fresh frozen female cadaver. Three senior Emergency Physicians have intubated the cadaver, and performed TUS or USB-endoscopy. We have prepared a randomized intubation list (n=96) in three blocks (3 times 32) as to include equal number of esophageal and tracheal intubations (48 for each). Each EP is performed all three interventions (intubation, TUS and USB-endoscopy) in consecutive blocks of 32 intubations, in turn. The position of the tube has been verified from a 2cm wide ostium on the proximal trachea.

RESULTS

In this study, all intubations (n=96, 100%) were correctly identified as tracheal or esophageal with both TUS and USB-camera. Both the sensitivity and specificity of TUS and USB-endoscopy for the CoETP were 100.0%.

CONCLUSION

The perfect accuracy of TUS and USB-endoscopy, have placed those techniques in a unique position as an alternative in resource-poor situations.

New decision formulas for predicting endotracheal tube depth in children: analysis of neck CT images

INTRODUCTION

The purpose of this study was to construct a prediction model for endotracheal tube depth using neck CT images.

METHODS

A retrospective image review was conducted that included patients who had undergone neck CT. Using sagittal neck CT images, we calculated the length between upper incisor and mid-trachea and then derived the model via regression analysis. The model was validated externally using chest radiographs of patients who had undergone endotracheal intubation. We compared performance of our model with that of other methods (Broselow tape and APLS formula) via Bland-Altman analysis and the percentage of estimations within 10% of the measured values.

RESULTS

A total of 1111 children were included in this study. The tube depth obtained from CT images was linearly related to body weight (tube depth (cm)=5.5+0.5×body wt (kg)) in children younger than 1 year and to height (tube depth (cm)=3+0.1×height (cm)) in children older than 1 year. External validation demonstrated that our new model showed better agreement with the desired tube depth than Broselow tape and APLS formula. The mean differences in children younger than 1 year were 0.61 cm and -1.24 cm for our formula and Broselow tape, respectively. The mean differences in children older than 1 year were -0.43 cm, -1.98 and -1.64 cm for our formula, Broselow tape and APLS formula, respectively. The percentages of estimates within 10% of the measured values were 52.7% and 35.8% for our formula and Broselow tape in children younger than 1 year, respectively, and 54.3%, 33.8% and 37.2% for our formula, Broselow tape and APLS formula in children older than 1 year, respectively (P<0.01).

CONCLUSION

Our new formula is useful and more accurate than the currently available methods.

Enhancement of chest radiographs obtained in the intensive care unit through bone suppression and consistent processing

Portable chest radiographs (CXRs) are commonly used in the intensive care unit (ICU) to detect subtle pathological changes. However, exposure settings or patient and apparatus positioning deteriorate image quality in the ICU. Chest x-rays of patients in the ICU are often hazy and show low contrast and increased noise. To aid clinicians in detecting subtle pathological changes, we proposed a consistent processing and bone structure suppression method to decrease variations in image appearance and improve the diagnostic quality of images. We applied a region of interest-based look-up table to process original ICU CXRs such that they appeared consistent with each other and the standard CXRs. Then, an artificial neural network was trained by standard CXRs and the corresponding dual-energy bone images for the generation of a bone image. Once the neural network was trained, the real dual-energy image was no longer necessary, and the trained neural network was applied to the consistent processed ICU CXR to output the bone image. Finally, a gray level-based morphological method was applied to enhance the bone image by smoothing other structures on this image. This enhanced image was subtracted from the consistent, processed ICU CXR to produce a soft tissue image. This method was tested for 20 patients with a total of 87 CXRs. The findings indicated that our method suppressed bone structures on ICU CXRs and standard CXRs, simultaneously maintaining subtle pathological changes.

Middle finger length-based tracheal intubation depth improves the rate of appropriate tube placement in children

BACKGROUND

It is challenging for anesthetists to determine the optimal tracheal intubation depth in children. We hypothesize that a measure three times the length of the middle finger can be used for predicting tracheal tube depth in children.

METHODS

Eighty-six children (4-14 years of age) were included in this study. After the children were anesthetized, a fiberoptic bronchoscope (FOB) was inserted into the trachea, the lengths from the upper incisor teeth to carina and vocal cords were measured, and a suitably sized cuffed tracheal tube was inserted into the trachea. Age-based and middle finger length-based formulas were used to determine the tracheal intubation depth.

RESULTS

All 86 children enrolled were included in this study. Compared with the age-based intubation, the rate of appropriate tube placement was higher for middle finger length-based intubation (88.37% vs 66.28%, P = 0.001). The proximal intubation rate was lower in middle finger length-based intubation (4.65% vs 32.56%, P < 0.001). There was only weak evidence for a difference in the distal intubation rate between the two methods (6.97% vs 1.16%, P = 0.054). The correlation coefficient between middle finger length and optimal tracheal tube depth was larger than that between age and optimal tracheal tube depth (0.883 vs 0.845).

CONCLUSIONS

Our data indicate that the appropriate tube placement rate can be improved by using three times the middle finger length as the tracheal intubation depth in children.

Assessment of three placement techniques for individualized positioning of the tip of the tracheal tube in children under the age of 4 years

BACKGROUND

Accurate positioning of the tip of the tracheal tube (tube tip) is challenging in young children. Prevalent clinical methods include placement of intubation depth marks, palpation of the tube cuff in the suprasternal notch, or deliberate mainstem intubation with subsequent withdrawal. To compare the predictability of tube tip positions, variability of the resulting positions in relation to the carina was determined applying the three techniques in each patient.

METHODS

In 68 healthy children aged ≤4 years, intubation was performed with an age-adapted, high-volume low-pressure cuffed tube adjusting the imprinted depth mark to the level of the vocal cords. The tube tip-to-carina distance was measured endoscopically. Thereafter, placements using (I) cuff palpation in the suprasternal notch and (II) auscultation to determine change in breath sounds during withdrawal after bronchial mainstem intubation were completed in random order.

RESULTS

Tube tip position above the carina was higher when using depth marks (mean = 36.8 mm) compared with cuff palpation in the suprasternal notch (mean = 19.0 mm). Variability, expressed as sd, was lowest with the mainstem intubation technique (5.2 mm) followed by the cuff palpation (7.4 mm) and the depth mark technique (11.2 mm) (P < 0.005).

CONCLUSION

Auscultation after deliberate mainstem intubation and cuff palpation resulted in a tube tip position above the carina that was shorter and more predictable than placement of the tube using depth markings.

Electrical impedance tomography for verification of correct endotracheal tube placement in paediatric patients: a feasibility study

BACKGROUND

Endotracheal tubes (ETTs) are frequently used in paediatric anaesthesia. Correct placement is crucial. The aim of this study was to evaluate electrical impedance tomography (EIT) for guiding and confirmation of paediatric ETT placement. In a retrospective analysis of stored EIT data, distribution of ventilation between left and right lung was used to verify correct paediatric ETT placement.

METHODS

Left and right lung ventilation was studied by EIT in 18 paediatric patients (median age: 53 months) requiring anaesthesia and endotracheal intubation. EIT was recorded before induction of anaesthesia, during mask ventilation, during ETT placement (including deliberate mainstem intubation), and after ETT repositioning according to the formula: ETT intubation depth (cm) = 3× ETT internal diameter (mm) or the mainstem intubation method (withdrawing the ETT 2 cm). Final ETT position was confirmed by fluoroscopy.

RESULTS

Following deliberate mainstem intubation, distribution of ventilation to the right lung was unequivocally demonstrated by EIT. Homogeneous distribution of ventilation between left and right lung monitored with EIT correlated in each patient with correct endotracheal ETT placement. The distribution of left and right lung ventilation differed significantly (P < 0.05) between the initial two-lung ventilation and subsequent right one-lung ventilation, and between right one-lung and subsequent two-lung ventilation according to auscultation and the final ETT position, respectively. In one patient, ETT was misplaced within the oesophagus which was also obvious from the EIT record.

CONCLUSION

This study demonstrates that EIT enables non-invasive recognition of correct ETT placement. Homogeneous right-left-lung ventilation is an indicator for correct ETT placement.

A comparative study of endotracheal tube positioning methods in children: safety from neck movement

BACKGROUND

The unexpected displacement of the endotracheal tube (ETT) as a result of neck movements can cause endobronchial intubation and accidental extubation. The ETT is subject to movement even after its proper placement has been confirmed either clinically or radiographically.

METHODS

One-hundred-seven children (2-8 yr) were divided randomly into three groups. In Group I, the ETT was entered into the main bronchus and withdrawn until equal sounds in both lung were heard, and then withdrawn 2 cm. In Group II, the ETT position was determined by placing the prescribed marks on the ETT at the level of the vocal cords, and in Group III, by palpating the ETT tip at the suprasternal notch. In all groups, the distance between the ETT tip and the carina was measured using a fiberoptic bronchoscope. The relative ETT tip position along the trachea (carina; 0%, vocal cords; 100%) was assessed in each position during neck movement.

RESULTS

The relative position of the ETT with the patient in the neutral position in Groups I, II, and III was 21.4% +/- 6.7%, 46.5% +/- 13.0%, and 43.4% +/- 11.1%, respectively. In Group I, the relative ETT position after flexion was 9.5% +/- 10.3%, and endobronchial intubation was observed in five children (14.3%). There was no extubation or endobronchial intubation in the other two groups.

CONCLUSIONS

Positioning the ETT by auscultation places the ETT more deeply than the midtrachea, which can increase the risk of endobronchial intubation during neck flexion.

Tracheal shortening during laparoscopic gynecologic surgery

BACKGROUND

During laparoscopic gynecologic surgery, pneumoperitoneum combined with the Trendelenburg position moves the carina towards the tip of the endotracheal tube (ETT), decreasing the margin of safety for the ETT position and increasing accidental endobronchial intubation. However, it remains to be established whether the tracheal length itself is actually changed. We conducted a prospective observational study to measure the change in the length of the trachea and the distance between the ETT tip and the carina in patients undergoing gynecologic laparoscopic surgery.

METHODS

Twenty-three patients scheduled for laparoscopic gynecologic surgery were enrolled. In the neutral position, the tracheal length was measured using a fiberoptic bronchoscope. The distance between the ETT tip and the carina was also measured. The tracheal length and the distance between the ETT tip and the carina were measured again 10 min after carbon dioxide (CO(2)) pneumoperitoneum (12-14 mmHg) combined with the Trendelenburg position (15 degrees ).

RESULTS

In the neutral position, the tracheal length was 11.09 +/- 0.90 cm and the distance between the ETT tip and the carina was 3.36 +/- 1.04 cm. After pneumoperitoneum combined with the Trendelenburg position, the distance between the ETT tip and the carina had decreased by 0.85 +/- 0.28 cm. The tracheal length had also decreased by 0.42 +/- 0.19 cm, which was equivalent to 49.7% of the decrease in the distance between the ETT tip and the carina.

CONCLUSIONS

These results suggest that tracheal shortening may contribute to a decrease in the distance between the ETT tip and the carina, increasing the risk of accidental endobronchial intubation during laparoscopic gynecologic surgery.

Use of the Rapiscope vs chest auscultation for detection of accidental bronchial intubation in non-obese patients undergoing laparoscopic cholecystectomy

STUDY OBJECTIVE

Main stem bronchial intubation is not always detected by routine means and may occur more frequently during laparoscopic procedures. Tracheal tube positional changes in non-obese patients undergoing laparoscopic cholecystectomy were detected by either the Rapiscope (Cook Critical Care, Bloomington, Ind) or chest auscultation.

DESIGN

Prospective, double-blind, crossover study.

SETTING

University hospital.

PATIENTS

Forty non-obese patients (BMI <28 kg.m(-2)), aged 18 to 80 years, American Society of Anesthesiologists risk class I-III, who underwent elective laparoscopic cholecystectomy were enrolled in this double-blind, prospective study.

INTERVENTIONS

After endotracheal intubation by one anesthesiologist, two other anesthesiologists assessed the tracheal tube's positioning by either the Rapiscope or chest auscultation; the results of one anesthesiologist's measurement were concealed from the other.

MEASUREMENTS

Assessments of the endotracheal tube tip's position were performed after intubation, head-down, and head-up positioning, after maximal abdominal insufflation and before extubation. At the same time points, Sp(O2), ET(CO2), and peak inspiratory pressures were also recorded.

MAIN RESULTS

Postintubation Rapiscope assessment revealed normal tracheal positioning of the tube's tip in all patients. Changes in tube's position were subsequently detected by the Rapiscope in 16 patients. In 8 cases, the tip moved endobronchially. Half of the endobronchial intubations occurred after maximal abdominal insufflation and the other half after changing the table position from neutral to 30 degrees head-down. Chest auscultation detected bronchial intubation in two cases only (P = .01). There were 4 additional events of downward movements and 4 events of cephalad migration of the tube's tip identified by the Rapiscope only. ET(CO2), Sp(O2), and peak inspiratory pressures did not change in patients who did experience bronchial intubation.

CONCLUSION

The Rapiscope detected significantly more events of endobronchial intubation as compared with chest auscultation; it could be considered useful during procedures where tracheal tube movements are potential.

Elongation of the Trachea During Neck Extension in Children: Implications of the Safety of Endotracheal Tubes

During neck extension, the changes in distance between endotracheal tube (ETT) tip and carina may not be equal to the changes in distance between vocal cords and ETT tip because of tracheal elongation. These distances are directly related to extubation risk. Using a fiberoptic bronchoscope, the distance between ETT tip and carina was measured in the neutral position after full extension of the neck in 25 children (2-8 yr old) scheduled for elective surgery under general anesthesia. The tracheal length was then measured in the neutral position and after full extension. The distance between vocal cords and ETT tip was calculated as the tracheal length minus the distance between ETT tip and carina. After full extension, the tracheal length (7.97 +/- 0.85 cm) was increased by 0.95 +/- 0.43 cm, and the change in distance between vocal cords and ETT tip was -1.08 +/- 0.47 cm, whereas the change in distance between ETT tip and carina was 2.02 +/- 0.58 cm. These results suggest that neck extension actually displaces the ETT tip to the vocal cords, increasing the risk of tracheal extubation in older children, although the actual displacement of ETT tip to vocal cords is reduced by tracheal lengthening.

IMPLICATIONS

The distance between endotracheal tube tip and vocal cords is directly related to the risk of exubation. Despite tracheal elongation, neck extension actually displaced the endotracheal tube tip to the vocal cords in older children.

Flexible endoscopy of aerodigestive tract in small infants

BACKGROUND

Flexible endoscopy (FE) is a useful method for diagnosing airway problems. Congenital or acquired airway lesions in infants may lead to respiratory distress that requires comprehensive investigation and management. This study was designed to evaluate the use of FE in small infants.

METHODS

Infants who had symptoms of respiratory distress and received FE when they were less than 1-year-old were studied and their medical history, diagnoses, interventions, and complications from FE were investigated.

RESULTS

The study population consisted of 568 small infants (334 boys and 234 girls) who weighed 5.1 +/- 2.4 kg, and received FE when they were 4.5 +/- 3.6 months of age. Most patients (91.2%) received diagnostic FE and the remainder (8.8%) received therapeutic procedures. Stridor (38.0%) was the most common indication for FE and laryngomalacia (33.3%) was the most frequent finding. Synchronous FE diagnosis was found in 351 (61.8%) cases. No major complications associated with FE were found.

CONCLUSION

Flexible endoscopy allows direct visualization of dynamic motion of the small aerodigestive tract. Laryngomalacia was the most common FE finding of respiratory distress in small infants. Synchronous FE lesions were frequently found in this young age group and it necessitated a thorough investigation of the entire aerodigestive tract.