The clinical implication of the vocal cords–carina distance in anaesthetized Chinese adults during orotracheal intubation

Measuring the outward migration of the nasotracheal tube at vocal cords with head and neck extension: a novel approach using a flexible bronchoscope in patients undergoing head and neck oncosurgery

BACKGROUND

Head and neck extension achieves optimal surgical exposure during head and neck oncosurgeries. However, it can lead to cephalad migration of the tracheal tube, causing complications. Preventing shallow intubation is essential, especially in patients with difficult airway. Using an innovative technique, we aimed to measure the proximal migration of the nasotracheal tube at the vocal cords on neck extension in patients with difficult airway.

METHODS

We enrolled 60 adult patients undergoing head and neck oncosurgeries with a mouth opening of less than 1.5 cm. After nasotracheal intubation using a flexible bronchoscope (FB), the FB was introduced into the adjacent nostril and maneuvered to reach the glottis. The FB was used to view and align the intubation depth mark (IDM) on the tracheal tube (TT) with the vocal cords in the neutral position. The outward migration of the TT at the vocal cords with a 30° to 40° neck extension was measured using the same maneuver. Also, the TT tip-to-carina distance was noted in both neutral and extension using FB.

RESULTS

The mean proximal migration of the TT at the vocal cords during neck extension was 3±0.3 mm. The TT tip-to-carina distance increased by a mean of 20±7 mm with extension. The proximal migration contributed 15%, whereas elongation of the trachea contributed 85% to this increase.

CONCLUSIONS

The major contributing factor for the increase in TT tip-to-carina distance on neck extension was tracheal elongation rather than outward migration of the TT at vocal cords.

Characteristics of lower airway parameters in an adult Asian population related to endotracheal tube design: a cadaveric study

The risk of endotracheal tube (ETT) placement includes endobronchial intubation and subglottic injury. This study aimed to describe the lengths of lower airway parameters related to cuff location and vocal cord markings in different adult-sized ETTs. Eighty cadavers were examined for the lengths of the lower airway, including their correlations and linear regressions with height. Thirty adult-sized ETTs from seven different brands were examined for Mark-Cuff and Mark-Tip distances. The depth of ETT placement was simulated for each brand using vocal cord marking. The mean (standard deviation) lengths from the subglottis, trachea, vocal cord to mid- trachea, and vocal cord to carina were 24.2 (3.5), 97.9 (8.6), 73.2 (5.3), and 122.1 (9.0) mm, respectively. Airway lengths were estimated as: (1) subglottis (mm) = 0.173 * (height in cm) - 3.547; (2) vocal cord to mid-trachea (mm) = 0.28 * (height in cm) + 28.391. There were variations in the Mark-Cuff and Mark-Tip distances among different ETTs. In the simulation, endobronchial intubation ranged between 2.5 and 5% and the cuff in the subglottis ranged between 2.5 and 97.5%. In summary, the lower airway parameters were height-related. ETT placement using vocal cord marking puts the patient at a high risk of cuff placement in the subglottis.

Effect of head position changes on the depth of tracheal intubation in pediatric patients: A prospective, observational study

PURPOSE

The purpose of this study was to investigate the effect of changing head position on the endotracheal tube (ETT) depth and to assess the risk of inadvertent extubation and bronchial intubation in pediatric patients.

METHODS

Subjects aged 4-12 years old with orotracheal intubation undergoing elective surgeries were enrolled. After induction, the distances between "the ETT tip and the trachea carina" (T-C) were measured using a Disposcope flexible endoscope in head neutral position, 45° extension and flexion, 60° right and left rotation. The distance of the ETT tip movement relative to the neutral position (ΔT-C) was calculated after changing the head positions. The direction of the ETT tip displacement and the adverse events including endobronchial intubation, accidental tracheal extubation, hoarseness and sore throat were recorded.

RESULTS

The ETT tip moved toward the carina by 0.5 ± 0.4 cm (P < 0.001) when the head was flexed. After extending the head, the ETT tip moved toward the vocal cord by 0.9 ± 0.4 cm (P < 0.001). Right rotation resulted that the ETT tip moved toward the vocal cord direction by 0.6 ± 0.4 cm (P < 0.001). Moreover, there was no displacement with the head on left rotation (P = 0.126). Subjects with the reinforced ETT had less ETT displacement after changing head position than the taper guard ETT.

CONCLUSION

The changes of head position can influence the depth of the ETT especially in head extension. We recommend using the reinforced ETT to reduce the ETT displacement in pediatrics to avoid intubation complications.

CLINICAL TRIAL REGISTRATION

[www.ClinicalTrials.gov], identifier, [ChiCTR2100042648].

Superficial placement of endotracheal tubes associated with unplanned extubation: A case-control study

INTRODUCTION

Unplanned extubations (UEs) refer to the inadvertent removal of endotracheal tubes (ETTs). Superficially placed ETTs anecdotally increases the risk of UEs. This study aims to assess the impact of ETT position as well as other factors that could be associated with risk of UEs.

METHOD

A retrospective case-control study was conducted at NewYork-Presbyterian Queens Hospital from January 2017 to February 2020. All adults admitted to intensive care units (ICUs) who received mechanical ventilation (MV) through ETTs were screened to identify UEs. For each case with UE, two controls with planned extubation were identified. A multivariate logistic regression was conducted to identify risk factors associated with UEs.

RESULTS

1100 patients received MV through ETTs during the time period. The incidence of UE was 4.9%. 53 patients with UEs and 106 patients with planned extubation were included for statistical analysis. Overall, patients with UE had higher in-hospital mortality rates (26.4% versus 11.3%, P = 0.02) and reintubation rates (28.3% versus 6.6%, P < 0.001). Within the UE group, patients who required reintubation had significantly higher in-hospital mortality rates than those who did not require reintubation (53.3% versus 15.8%, P = 0.005). Multivariate logistic regression showed higher APACHE II scores (Odds ratios (OR) 1.07; 95% Confidence interval (CI), 1 to 1.13), distance of ETT tips to carina ≥6 cm (OR 6.41; 95% CI, 1.1 to 37.3), physical restraint use (OR 2.98; 95% CI, 1.28 to 6.95) and continuous infusions of sedatives and/or analgesics (OR 10.72, 95% CI, 4.19 to 27.43) were associated with UE.

CONCLUSION

UE and the need for reintubation is associated with worse outcomes. Distance of ETT tips to carina ≥6 cm may be associated with higher risks of UE. Further prospective studies are needed to establish the optimal position of ETT to prevent UE.

Comparison of the selection of nasotracheal tube diameter based on the patient's sex or size of the nasal airway: A prospective observational study

When selecting the nasotracheal tube diameter for nasotracheal intubation, atraumatic introduction of the tube through the nasal passage and a safe location of the tube's cuff and tip should be ensured simultaneously. To maintain safety margin for the tube's cuff and tip from the vocal cords and carina (2 cm and 3 cm, respectively), the maximum allowable proximal-cuff-to-tip distance was calculated as 5 cm less than the measured vocal cords-to-carina distance. The primary aim of this study was to find a single predictive preoperative factor of the nostril size and maximum allowable proximal-cuff-to-tip distance of nasotracheal tubes. The secondary aim was to compare the difference in the safety margin between the maximum allowable proximal-cuff-to-tip distance based on the patient's airway and the actual proximal-cuff-to-tip distance of the selected tube. We used fiberoptic bronchoscope to measure the distance from the vocal cords to the carina for the calculation of the maximum allowable proximal-cuff-to-tip distance. We analyzed the association of preoperative characteristics such as age, sex, height, and weight with the nostril size and maximum allowable proximal-cuff-to-tip distance. The proportion of patients with appropriate locations of both the cuff and tip was evaluated. Sex and height were significant predictive factors of the nostril size and maximum allowable proximal-cuff-to-tip distance, respectively (p = 0.0001 and p = 0.0048). The difference in the safety margin was significantly decreased when the tube diameter was selected based on the nostril size rather than by sex (p<0.0001). The proportion of patients who had the appropriate cuff/tip location was significantly larger (75.2%) when the tube diameter was selected by sex compared to when it was selected by the nostril size (65%) (p<0.0001). It is more suitable to select the nasotracheal tube diameter based on sex rather than by nostril size to ensure the safe location of the tube's cuff and tip simultaneously.

Use of the Microcuff® During General Anesthesia for Patients With Scoliosis

Scoliosis may often be associated with a variety of cardiovascular and respiratory conditions or diseases, and depending on the severity of the spinal deformity, it may also complicate anesthetic management because of the difficulty of neck extension and tracheal deformity. Therefore, patients with scoliosis may require careful perioperative anesthetic considerations. A 14-year-old girl was scheduled to undergo extractions and restorative treatment for dental caries under general anesthesia. Her medical history was significant for intellectual disability and autism as well as previously undiagnosed scoliosis. After fixation of a 6.0 Portex^® endotracheal tube (ETT), percutaneous oxygen saturation (SpO₂) decreased to 93%, peak airway pressures increased, and unilateral lung ventilation was noted. Inadvertent mainstem bronchial intubation was immediately suspected, prompting removal of the Portex ETT and reintubation with a shorter 6.0 Microcuff^® ETT. The dental treatment was completed successfully without further incident. Assessment of the ETTs used intraoperatively led to the determination that the distance from the glottis to the carina was considerably shorter than normal for this patient. It was speculated that the Microcuff ETT may be optimal for anesthetic management of scoliosis patients because of its shorter lengths compared with other style ETTs, which may reduce the risk of bronchial intubation in such cases.

A Formula for Estimating the Appropriate Tube Depth for Intubation

An estimation of the appropriate tubing depth for fixation is helpful to prevent inadvertent endobronchial intubation and prolapse of cuff from the vocal cord. A feasible estimation formula should be established. We measured the anatomical length of the upper-airway tract through the oral and nasal pathways on cephalometric radiographs and tried to establish the estimation formula from the height of the patient. The oral upper-airway tract was measured from the tip of the incisor to the vocal cord. The nasal upper-airway tract was measured from the tip of the nostril to the vocal cord. The tracts were smoothly traced by using software. The length of the oral upper-airway tract was 13.2 ± 0.8 cm, and the nasal upper-airway tract was 16.1 ± 0.9 cm. We found no gender difference ( p > .05). The correlations between the patients' height and the length of the oral and nasal upper-airway tracts were 0.692 and 0.760, respectively. We found that the formulas (height/10) - 3 (in cm) for oral upper-airway and (height/10) + 1 (in cm) for nasal upper-airway tract are the simple fit estimation formulas. The average error and standard deviation of the estimated values from the measured values were 0.50 ± 0.66 cm for the oral tract and 0.39 ± 0.63 cm for the nasal tract. Thus, considering the length of the intubation marker of each product (DM), we would like to propose the length of tube fixation as (height/10) + 1 + DM for nasal intubation and (height/10) - 3 + DM for oral intubation. In conclusion, the estimation formulas of (height/10) - 3 + DM and (height/10) + 1 + DM for oral and nasal intubation, respectively, are within almost 1 cm error in most cases.

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.

Determining correct tracheal tube insertion depth by measuring distance between endotracheal tube cuff and vocal cords by ultrasound in Chinese adults: a prospective case-control study

OBJECTIVES

Unrecognised malposition of the endotracheal tube can lead to severe complications in patients under general anaesthesia. The purpose of this study was to verify the feasibility of using ultrasound to measure the distance between the upper edge of saline-inflated cuff and the vocal cords.

DESIGN

Prospective case-control study.

SETTING

A tertiary hospital in Beijing, China.

METHODS

In this prospective study, 105 adult patients who required general anaesthesia were enrolled. Prior to induction, ultrasound was used to identify the position of the vocal cords. After intubation, the endotracheal tube (ETT) was fixed at a depth of 23 cm at the upper incisors in men and 21 cm in women. The depth of intubation was verified by video-assisted laryngoscopy. The distance between the upper edge of the saline-inflated cuff and the vocal cords was measured by ultrasound; the ideal distance was considered to be 1.9-4.1 cm.

RESULTS

Among the 105 cases, two cuffs were too close to the vocal cords and one too far away from the vocal cords. These diagnoses were made by ultrasound and were in agreement with results from direct laryngoscopy. The overall accuracy of ultrasound in identifying malposition of the cuff was 100.0% (95% CI: 96.6% to 100%). The sensitivity, specificity, positive predictive value and negative predictive value of ultrasound were, respectively, 100% (95% CI: 96.5% to 100%), 100% (95% CI: 29.2% to 100%), 100% (95% CI: 96.5% to 100%) and 100% (95% CI: 29.2% to 100%).

CONCLUSION

Identification of the upper edge of the saline-inflated cuff and the vocal cords by ultrasound to assess the location of the ETT is a reliable method. It can be used to avoid malposition of the ETT cuff and reduce the incidence of vocal cords injury after intubation.

TRIAL REGISTRATION NUMBER

ChiCTR-DDD-17011048.

A multi-center evaluation of a disposable catheter to aid in correct positioning of the endotracheal tube after intubation in critically ill patients

PURPOSE

To demonstrate that use of a minimally invasive catheter reduces endotracheal tube (ETT) malposition rate after intubation.

MATERIALS AND METHODS

This study is a multi-center, prospective observational cohort of intubated patients in the medical intensive care unit. The catheter was inserted into the ETT immediately after intubation. The ETT was adjusted accordingly based on qualitative color markers on the catheter. A confirmatory chest radiograph was obtained to determine the ETT position. Malposition of the ETT was defined by the distal ETT not being within 2-5 cm above the carina.

RESULTS

Sixty-nine patients were enrolled, age 56.2 ± 19.5 years, body mass index 31.0 ± 13.8 kg/m². The catheter prompted repositioning of the ETT in 39 (56.5%) patients. Using the catheter, the rate of malposition decreased to 7.2%, with the distal ETT position at 3.7 ± 1.2 cm above the carina. Without the catheter, the ETT malposition rate would have been 39.1%. The time for catheter use and chest radiograph completion at our institutions was 1.7 ± 1.5 and 44.4 ± 36.4 min, respectively.

CONCLUSIONS

With use of an ETT positioning catheter after intubation, the ETT malposition rate was reduced by 82%. This catheter-based system was safe, and its use may perhaps decrease the need for the post-intubation chest radiograph.

Measuring Endotracheal Tube Depth by Bedside Ultrasound in Adult Patients in an Intensive Care Unit: A Pilot Study

The aim of the study described here was to evaluate the feasibility and accuracy of measuring endotracheal tube (ETT) depth with ultrasound in adult patients in an intensive care unit (ICU). The distance between the upper margin of the cuff and the upper margin of the aortic arch (Duc-ua) of 67 ICU patients was measured by ultrasound, and the time of measurement was recorded. The level of agreement between the distance between the tip of the ETT and the carina (Dtt-c) measured by ultrasound (U-Dtt-c) and Dtt-c measured by bronchoscopy (B-Dtt-c) was assessed using linear regression and a Bland-Altman plot. There was a significant correlation between B-Dtt-c and U-Dtt-c (r = 0.844, p < 0.001). Also, the Bland-Altman plot revealed strong agreement between B-Dtt-c and U-Dtt-c. The time it took to measure ETT depth by ultrasound was 33.91 ± 5.43 s. In conclusion, bedside ultrasound provides a novel and convenient method for measuring the depth of ETT in ICU patients.

The Tracheal Accordion and the Position of the Endotracheal Tube

The purpose of this review is to, first, determine the static factors that affect the length of the human trachea across different populations and, second, to investigate whether or not there are dynamic factors that cause the length of the human trachea to vary within the same individual. We also investigated whether these changes in tracheal length within the same individual are significant enough to increase the risk of endobronchial intubation or accidental extubation. A PubMed/MEDLINE and a Web of Science database English-language literature search was conducted in May 2016 with relevant keywords and MeSH terms when available. We found that gender, extremes of age, patient height, postsurgical changes and co-existing disease are static patient factors that affect the length of the human trachea. Dynamic clinical changes that occur under anaesthesia, including Trendelenburg position, head and neck flexion and extension, paralysis of the diaphragm and pneumoperitoneum, cause the trachea to act as an accordion, decreasing and increasing its length. The length of the human trachea in both awake and anaesthetised and paralysed patients is a critical consideration in preventing both endobronchial intubation and tracheal extubation. It is clear from the literature that tracheal length varies widely across populations and, additionally, with the dynamic clinical changes that occur under anaesthesia, the trachea acts as an accordion decreasing and increasing its length within the same individual. Knowledge of the magnitude of the change in tracheal dimensions in response to these factors is an important clinical consideration.

Retrospective analysis of vocal cord-to-suprasternal notch distance: Implications for preventing endotracheal tube cuff-induced vocal cord injury

Endotracheal tube (ETT) positioning using the cuff ballottement test, which confirms that the inflated cuff is positioned at the suprasternal notch with squeezing or inflating a pilot balloon, has been reported to be a simple and reliable method of preventing endobronchial intubation. However, in patients with a short vocal cord-to-suprasternal notch, ETT placement using the cuff ballottement test can cause vocal cord injury. In the present study, we assessed the distance from a point 15 mm below the vocal cord to the suprasternal notch (VSD-15), the safe position for ETT cuff placement above the suprasternal notch, and investigated variables for predicting VSD-15.We retrospectively examined neck computed tomography in 427 adult patients and measured VSD-15 and the distance from the thyroid notch to the suprasternal notch (TSD). Patient height, weight, sex, and age were also recorded.In total, 47 patients (11.0%) showed a VSD-15 shorter than 45 mm. VSD-15 significantly correlated with TSD (r = 0.778, P < 0.001) and height (r = 0.312, P < 0.001), and inversely correlated with age (r = -0.321, P < 0.001). In multiple linear regression models, a formula was obtained for VSD-15 (VSD-15 [mm] = -6.220 + 0.744 × TSD [mm] + 0.092 × height [cm] - 0.065 × age [years], R = 0.621).The cuff ballottement test should be used cautiously in patients with a predicted short VSD-15. VSD-15 can be predicted from TSD, height, and age.

Inadvertent Endobronchial Intubation in a Patient With a Short Neck Length

Inadvertent placement of the endotracheal tube into the right bronchus during intubation for general anesthesia is a fairly common occurrence. Many precautions should be taken by the anesthesia provider in order to minimize the incidence of endobronchial intubation, including bilateral auscultation of the lungs, use of the 21/23 rule, and palpation of the inflated endotracheal cuff at the sternal notch. These provisions, however, are not foolproof; anesthesia providers should realize that endobronchial intubation may occur from time to time because of variations in patient anatomy, changes in patient positioning, and cephalad pressures exerted during surgery. A 58-year-old man with chronic obstructive pulmonary disease received general endotracheal anesthesia for a laparoscopic cholecystectomy. His height was 165 cm (5 ft, 5 in) and the endotracheal tube was secured at his incisors at 21 cm after placement with a rigid laryngoscope. Bilateral breath sounds were confirmed with auscultation, although they were distant because of his chronic obstructive pulmonary disease. After radiographic examination in the postanesthesia care unit, a right main-stem intubation was revealed to have taken place, resulting in complete atelectasis of the left lung. After repositioning of the endotracheal tube, radiography confirmed that the patient had an anatomically short tracheal length.

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.

Appropriate depth of placement of oral endotracheal tube and its possible determinants in Indian adult patients

Background:

Optimal depth of endotracheal tube (ET) placement has been a serious concern because of the complications associated with its malposition.

Aims:

To find the optimal depth of placement of oral ET in Indian adult patients and its possible determinants viz. height, weight, arm span and vertebral column length.

Settings and Design:

This study was conducted in 200 ASA I and II patients requiring general anaesthesia and orotracheal intubation.

Methods:

After placing the ET with the designated black mark at vocal cords, various airway distances were measured from the right angle of mouth using a fibre optic bronchoscope.

Statistical Analysis:

The power of the study is 0.9. Mean (SD) and median (range) of various parameters and Pearson correlation coefficient was calculated.

Results:

The mean (SD) lip-carina distance, i.e., total airway length was 24.32 (1.81) cm and 21.62 (1.34) cm in males and females, respectively. With black mark of ET between vocal cords, the mean (SD) ET tip-carina distance of 3.69 (1.65) cm in males and 2.28 (1.55) cm females was found to be considerably less than the recommended safe distance.

Conclusions:

Fixing the tube at recommended 23 cm in males and 21 cm in females will lead to carinal stimulation or endobronchial placement in many Indian patients. The lip to carina distance best correlates with patient's height. Positioning the ET tip 4 cm above carina as recommended will result in placement of tube cuff inside cricoid ring with currently available tubes. Optimal depth of ET placement can be estimated by the formula “(Height in cm/7)-2.5.”

Subglottal resonances of adult male and female native speakers of American English

This paper presents a large-scale study of subglottal resonances (SGRs) (the resonant frequencies of the tracheo-bronchial tree) and their relations to various acoustical and physiological characteristics of speakers. The paper presents data from a corpus of simultaneous microphone and accelerometer recordings of consonant-vowel-consonant (CVC) words embedded in a carrier phrase spoken by 25 male and 25 female native speakers of American English ranging in age from 18 to 24 yr. The corpus contains 17,500 utterances of 14 American English monophthongs, diphthongs, and the rhotic approximant [[inverted r]] in various CVC contexts. Only monophthongs are analyzed in this paper. Speaker height and age were also recorded. Findings include (1) normative data on the frequency distribution of SGRs for young adults, (2) the dependence of SGRs on height, (3) the lack of a correlation between SGRs and formants or the fundamental frequency, (4) a poor correlation of the first SGR with the second and third SGRs but a strong correlation between the second and third SGRs, and (5) a significant effect of vowel category on SGR frequencies, although this effect is smaller than the measurement standard deviations and therefore negligible for practical purposes.

Vocal Cords-Carina Distance in Anaesthetised Caucasian Adults and its Clinical Implications for Tracheal Intubation

Previous work has assessed vocal cords-carina distance in Chinese patients and compared it to commonly used tracheal tubes. In addition, an attempt was made to identify surface anatomy measurements with short tracheas. We have examined the length of tracheas in Caucasian patients and compared it with currently used tracheal tubes. We have investigated a wider range of surface anatomy measurements in an attempt to correlate measurements with vocal cords-carina distance and identifying patients who may be at risk of endobronchial intubation. In this study, the vocal cords-carina distance was measured in 150 anaesthetised Caucasian patients with a fibreoptic bronchoscope. We also attempted to correlate height and various surface anatomy measurements on the patients’ chest, neck and limb regions to predict those patients at risk of endobronchial intubation. The mean vocal cords-carina distance was 12.7 cm (standard deviation 1.6 cm). The best predictors in our study of vocal cords-carina distance less than 11.3 cm were a height of ≤182 cm, an ulnar length of ≤31.2 cm or a thyroid to xiphisternum distance of ≤31.8 cm. This correlation is poor however, and prediction of vocal cords-carina distance remains difficult clinically. It was therefore concluded that surface anatomy measurements are a poor predictor of vocal cords-carina distance.

Sore Throat or Hoarse Voice with Bronchial Blockers or Double-Lumen Tubes for Lung Isolation: A Randomised, Prospective Trial

Double-lumen endotracheal tubes and bronchial blockers allow lung isolation for one-lung ventilation. Few studies, however, directly compare these devices. Further, a new endobronchial blocker (Coopdech) is available in some countries. Our primary hypothesis was that bronchial blockers would be associated with less sore throat or hoarse voice than double-lumen tubes. Secondary outcomes were successful one-lung ventilation and surgical access. In this prospective trial, 120 Chinese patients undergoing elective surgery were randomly assigned to one of four groups of 30 patients: Coopdech blocker, Arndt blocker, Univent tube or double-lumen tube. Postoperative sore throat and hoarse voice were assessed in the recovery room and 24 hours after surgery. The incidence and severity of sore throat or hoarse voice was less in the blocker groups than double-lumen tube group: Coopdech 13%, Arndt 20%, Univent 30% and double-lumen tube 60%, P <0.001. The blocker groups did not significantly differ, P=0.28. Compared to the double-lumen tubes the bronchial blockers took about two minutes less to position but five minutes longer for lung deflation. Surgical exposure was uniformly good across the four groups. We conclude that clinical use of the Coopdech endobronchial blocker is similar to the Arndt and Univent blockers and that all three are associated with less sore throat or hoarse voice than double-lumen tubes.