Endotracheal Tube Internal Diameter Research Articles

The difference in rotation angle of the distal endotracheal tube through nasal approach

BackgroundNasal intubation using a fiberoptic scope is a useful technique. In clinical practice, we have experienced difficulty in advancing the endotracheal tube (ETT) over the fiberoptic scope because of resistance to the passage of the ETT against rotation in the nasal cavity, when it gets hung up on structures of the laryngeal inlet. Several maneuvers have been proposed to overcome this difficulty. The gap between the tip of the ETT and the fiberoptic scope can be reduced using a thicker fiberoptic scope and a thinner ETT. Moreover, simultaneous rotation of the fiberoptic scope and ETT could lead to successful intubation by reducing impingement on the ETT. However, the discrepancy between these rotation angles is unclear. This observational prospective study aimed to investigate the discrepancy in the rotation angle between the ETT and fiberoptic scope during nasal intubation.MethodsThe patients (aged 20–80 years) who underwent nasal intubation for oral and maxillofacial surgery participated in three sizes of preformed nasal ETT and were intubated using a fiberoptic scope. They were divided into three groups; the ETT internal diameter (ID) 6.5 mm (6.5 group), ID 7.0 mm (7.0 group), and ID 7.5 mm (7.5 group). The ETT was then inserted through the nasal cavity into the pharynx. After the fiberoptic scope was advanced through the ETT above the glottis, simultaneous rotation by both the proximal end of the fiberoptic scope and ETT was performed in 90° and 180° in both right (clockwise) and left (counterclockwise) directions, and the rotation angle at the distal end of the ETT was monitored using a video laryngoscope (Pentax-AWS).ResultsA total of 39 patients were included in the study. When both the proximal end of the fiberscope and ETT were simultaneously rotated by 90°, in the 6.5 group (n = 13), the distal end of the ETT rotated by 47.8 ± 1.5°. In the 7.0 °group (n = 13), the distal end of the ETT rotated by 45.5 ± 1.0°. In the 7.5 group (n = 13), the distal end of the ETT rotated by 39.9 ± 1.0°. When the proximal end of the fiberscope and ETT were rotated by 180°, in the 6.5 group, the distal end of the ETT rotated by 166.2 ± 2.5°. In the 7.0 group, the distal end of the ETT rotated by 145.7 ± 2.2°. In the 7.5 group, the distal end of the ETT rotated by 115.1 ± 2.0°. All rotation angles in the distal end of the ETT were significantly lower than those in both the proximal end of the fiberscope and ETT (p < 0.05). Rotating right by 180° was significantly different among the three groups (p < 0.05), although rotating right by 90° was not significantly different. Similar results were obtained for the left rotation.ConclusionSimultaneous rotation by the proximal end of the ETT and fiberscope above the glottis for the nasal approach induced significant differences in the distal end of the ETT. The larger tube lagged by the resistance of the nasal passages during rotation. Therefore, the ETT does not rotate as much as the rotation angle.Trial registrationThis prospective observational study was conducted after receiving approval from the Ethics Review Board of Kyushu University Hospital (Approval No. 30–447).

Development and internal validation of an equation using anthropometric measures to predict correct endotracheal tube insertion depth.

PurposeTo develop, internally validate, and assess the utility of implementing a regression model for determining endotracheal tube (ETT) insertion depth.Research methodsWe recorded height, weight, age, sex, ETT internal diameter (ID), lip marking, and tracheal position from the electronic record from a random subset of 2,000 intubated subjects obtained from 1 January 2009 to 5 May 2012. A multivariable linear regression model was constructed and validated by a nonparametric bootstrapping technique using unrestricted random sampling methods. A prospective pilot of subjects admitted to the pediatric intensive care unit requiring invasive mechanical ventilatory support was conducted from 7 January 2019 to 31 May 2019. Those with spinal and/or skeletal malformations, without a post-intubation chest-x-ray (CXR) order, or whose CXR quality impaired visualizing the carina and ETT tip, were excluded. The validated regression equation determined insertion depth. CXR following intubation determined ETT position. Demographic data were summarized. Two-tailed, one-sample binomial test of proportions assessed differences in the proportion of correct position by the equation.Main findingsFour hundred and seventy-seven subjects included in model construction yielded 10,000 independent samples for internal validation; 55% were female, and the mean age (SD) was 47 (63) months. Bias between bootstrap coefficients and refined model estimates were negligible (P < 0.01). Eleven subjects in the pilot were female (64%), mean age (SD) of 36.7 (38) months. Four protocol violations (36.4%) resulted in malposition. Subsequent repositioning per protocol resulted in 100% correct positioning (P = 0.01).ConclusionThe regression equation [0.8636 * (Ht. 0.6223)] facilitated correct ETT placement. A larger, diverse sample is required for external model validation.

Accuracy of pediatric advanced life support method for predicting the depth of endotracheal tube in Indonesian children

BACKGROUND The pediatric advanced life support (PALS) method can predict the depth of endotracheal tube (ETT) in pediatric patients easily, but it has limitations due to variations in the children’s characteristics, especially the racial consideration. This study compared the accuracy of ETT depth prediction based on the PALS methods in Indonesian children. METHODS Patients aged 0–12 years, who underwent elective surgery with oral intubation, were recruited consecutively based on their ages: 0–24 months and 25 months–12 years for this cross-sectional study in Cipto Mangunkusumo Hospital, Jakarta, Indonesia from June to August 2014. Bland–Altman analysis was used to compare the two measurement methods: PALS method to predict the ETT depth accuracy and auscultation method to confirm the position of the ETT. Furthermore, correlation analysis was done to examine the relationship of age, weight, height, and ETT internal diameter with ETT depth. RESULTS 50 patients were recruited in each group. Bland–Altman test of ETT depth in the 0–24 months age group showed a 1.18 cm mean difference from confirmation using the auscultation method (limits of agreement −0.71 to 3.08). The 25 months–12 years age group showed a 1.11 cm mean difference with limits of agreement were −0.95 to 3.17 from confirmation using the auscultation method. Age and weight had the strongest correlation value to ETT depth in the 25 months–12 years age group (R2 = 62.3%). CONCLUSIONS The PALS method is inaccurate for predicting ETT depth in Indonesian children aged 0–12 years old compared with the auscultation method.

Accuracy of a Chest X-Ray-Based Method for Predicting the Depth of Insertion of Endotracheal Tubes in Pediatric Patients Undergoing Cardiac Surgery.

The incidence of endotracheal tube (ETT) malposition in children with various described methods is 15% to 30%. Chest x-ray (CXR) is the gold standard for confirming appropriate ETT position. The aim of this study was to measure the accuracy of a preoperative CXR-based method in determining depth of insertion of ETTs and to compare it with methods based on the intubation depth mark or formulae (age, height, and ETT internal diameter) in children undergoing cardiac surgery. Prospective observational study. University-affiliated tertiary care hospital. Sixty-six consecutive children scheduled for elective pediatric cardiac surgery. None. The distance from carina to mid-trachea was measured for each child preoperatively on the CXR displayed as a computed radiography image in a picture archival and communications system computer. Following intubation, ETTs deliberately were pushed endobronchially and then pulled back to the carina; they were further withdrawn by the previously measured carina to mid-tracheal distance and secured. CXRs postoperatively were repeated to confirm ETT position. The ETT position was measured with other methods using the picture archival and communications system ruler on the postoperative CXR and compared with the CXR method. The proportion of appropriate ETT position with the CXR method was 98.5% (p≤0.001 v other methods). In children younger than 3 years, the appropriate proportion was 97.4%. The appropriate positioning of ETTs in the trachea by the CXR method is superior to other methods.

In vitro performance comparison of the Sensormedics 3100A and B high-frequency oscillatory ventilators

The Sensormedics 3100A and 3100B are widely used to provide high-frequency oscillatory ventilation in clinical practice. Infants and children <35 kg are typically oscillated with the 3100A and >35 kg with the 3100B. This study compares the effect of ventilator and patient parameters on delivered tidal volume during high-frequency oscillatory ventilation of a test lung with these devices. Laboratory-based study. Test lung and Sensormedics 3100A and 3100B high-frequency oscillators. A previously validated hot-wire flowmeter (Florian) was placed in series with either a 3100A (n = 3) or 3100B (n = 3) ventilator and a Michigan test lung. Tidal volumes were measured over a range of mean airway pressure, inspiratory:expiratory ratio, frequency, pressure amplitude, and endotracheal tube internal diameter. The 3100A and 3100B delivered similar tidal volumes across a range of ventilator parameters for an inspiratory:expiratory ratio of 1:1, differing by <10%. However, at an inspiratory:expiratory ratio of 1:2, there was a statistically significant decrease in tidal volume for the 3100B compared with the 3100A at lower frequencies, which was partially mitigated by increasing pressure amplitude. The difference in the generated pressure and flow waveforms may account for the observed tidal volume differences between the high-frequency oscillatory ventilation models. Delivered tidal volume was highly dependent on endotracheal tube size. Multiple variables contribute to the delivered tidal volume during high-frequency oscillatory ventilation, including ventilator model selection and endotracheal tube size. It is possible that real-time, clinical monitoring of delivered tidal volume during high-frequency oscillatory ventilation would allow better titration and maximize performance of these ventilators in caring for critically ill patients.

Sound Analysis in anIn VitroEndotracheal Tube Model

Background/AimsComplete endotracheal tube obstruction is a medical emergency, and partial occlusion causes increased breathing rates and failure to wean off mechanical ventilation. Partial occlusion may be underestimated due to the lack of proper detection methods. We tested whether the sound of an endotracheal tube could be used to detect an endotracheal tube obstruction using an in vitro model.MethodsAn endotracheal tube was connected to a ventilator on one end and a test lung on the other. Sounds were recorded with a microphone located inside the endotracheal tube via a connector. During mechanical ventilation, we changed the endotracheal tube internal diameter from 5.0 to 8.0 mm and different grades of obstruction at different sites were used along the tube. Sound energy was compared among the different conditions.ResultsThe energy of endotracheal tube sounds was positively correlated with the internal diameter and negatively correlated with the degree of obstruction. The rate of decline in energy differed with obstruction location. When the obstruction was more distal, the rate of decline in endotracheal sound energy was more rapid.ConclusionsChanges in the sound of an endotracheal tube can be used to detect an obstruction. Further studies are needed for clinical application.

Tidal volume delivery during high-frequency oscillatory ventilation in adults with acute respiratory distress syndrome*

a) Characterize how ventilator and patient variables affect tidal volume during high-frequency oscillatory ventilation; and b) measure tidal volumes in adults with acute respiratory distress syndrome during high-frequency oscillatory ventilation. Observational study. Research laboratory and medical intensive care unit. Test lung and patients with acute respiratory distress syndrome. Using a previously validated hot wire anemometer placed in series with a Sensormedics 3100B high-frequency ventilator, an endotracheal tube, and a test lung, tidal volume was measured at different combinations of frequency (4, 6, 8, 10, and 12 Hz), pressure amplitude (50, 60, 70, 80, and 90 cm H2O), mean airway pressure (20, 30, and 40 cm H2O), test lung compliance (10, 30, and 50 mL/cm H2O), endotracheal tube internal diameter (6, 7, and 8 mm), bias flow (20, 30, and 40 L/min), and inspiratory/expiratory ratio (1:2 and 1:1). In patients, tidal volume was measured at baseline ventilator settings and at baseline frequency +/-2 Hz and baseline pressure amplitude +/-10 cm H2O. Measured tidal volumes were 23-225 mL during high-frequency oscillatory ventilation of the test lung. A 2-Hz increase in frequency and a 10-cm H2O increase in pressure amplitude caused a 21.3% +/- 4.1% decrease and 21.4% +/- 3.4% increase in tidal volume, respectively. Decreasing endotracheal tube internal diameter from 8 mm to 7 mm and from 7 mm to 6 mm caused a 15.3% +/- 1.7% and 18.9% +/- 2.1% reduction in tidal volume, respectively. Increasing bias flow from 20 L/min to 30 L/min increased tidal volume by 11.2% +/- 3.9%. Further increases in bias flow, changes in compliance, and changes in mean airway pressure had little effect. Tidal volumes measured in acute respiratory distress syndrome patients were 44-210 mL. A 2-Hz increase in frequency was associated with a 23.1% +/- 6.3% decrease in tidal volume. In contrast to the test lung data, a 10-cm H2O increase in pressure amplitude resulted in only a 5.6% +/- 4.5% increase in tidal volume. Tidal volumes are not uniformly small during high-frequency oscillatory ventilation. The primary determinant of tidal volume in adults with acute respiratory distress syndrome during high-frequency oscillatory ventilation with the Sensormedics 3100B is frequency. Test lung findings suggest that endotracheal tube internal diameter is also an important determinant of tidal volume.

Inspiratory oscillatory flow with a portable ventilator: a bench study

IntroductionWe observed an oscillatory flow while ventilating critically ill patients with the Dräger Oxylog 3000™ transport ventilator during interhospital transfer. The phenomenon occurred in paediatric patients or in adult patients with severe airway obstruction ventilated in the pressure-regulated or pressure-controlled mode. As this had not been described previously, we conducted a bench study to investigate the phenomenon.MethodsAn Oxylog 3000™ intensive care unit ventilator and a Dräger Medical Evita-4 NeoFlow™ intensive care unit ventilator were connected to a Dräger Medical LS800™ lung simulator. Data were registered by a Datex-S5™ Monitor with a D-fend™ flow and pressure sensor, and were analysed with a laptop using S5-Collect™ software. Clinical conditions were simulated using various ventilatory modes, using various ventilator settings, using different filters and endotracheal tubes, and by changing the resistance and compliance. Data were recorded for 258 combinations of patient factors and respirator settings to detect thresholds for the occurrence of the phenomenon and methods to overcome it.ResultsUnder conditions with high resistance in pressure-regulated ventilation with the Oxylog 3000™, an oscillatory flow during inspiration produced rapid changes of the airway pressure. The phenomenon resulted in a jerky inspiration with high peak airway pressures, higher than those set on the ventilator. Reducing the inspiratory flow velocity was effective to terminate the phenomenon, but resulted in reduced tidal volumes.ConclusionOscillatory flow with potentially harmful effects may occur during ventilation with the Dräger Oxylog 3000™, especially in conditions with high resistance such as small airways in children (endotracheal tube internal diameter <6 mm) or severe obstructive lung diseases or airway diseases in adult patients.