Can insertion length for a double-lumen endobronchial tube be predicted?

Insertion depth of left-sided double-lumen endobroncheal tube: A new predictive formula

Background:

In the field of thoracic anesthesia, it is well-established practice that the insertion depth of left-sided double-lumen tube (LDLT) is achieved after checking its position via fiberoptic bronchoscopy (FOB). Several studies have shown positive correlation between body height (BH) and the optimal insertion depth of a LDLT. Each of these studies has developed a formula for proper insertion depth of the LDLT. In this study, we prospectively studied our patients whose tracheas were intubated correctly with LDLT using FOB confirmation and examined the optimal insertion depth of LDLT aiming at finding a formula suitable for our patients.

Methods:

After obtaining the institutional review board approval of College of Medicine Research Centre, King Saud University, we recruited 41 adult patients who underwent thoracic surgery with one-lung ventilation (OLV). The study included patients whose procedure required placement of a LDLT. The optimal insertion depth of the LDLT was confirmed using FOB. The following variables were recorded, the patient's sex, age, BH, and the final correct insertion depth of the LDLT (cm) measured from the corner of the mouth. The results of LDLT insertion depth in our study were compared to another published five studies. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) version 22 software (SPSS Inc., Chicago, IL, USA).

Results:

Positive correlation was found between BH (cm) and insertion depth of LDLT (cm) since r = 0.744 (P < 0.05). Also, positive correlation was found between the LDLT size (Fr) and insertion depth of LDLT (cm) since r = 0.792 (P < 0.05) where r is Pearson's correlation coefficient. By fit curve (Curve Estimation), we were able to get the predicted equation for our cases as follow: the insertion depth of LDLT (cm) =0.249 × (BH)^0.916 with significant correlation to the other five formulae (P < 0.05).

Conclusion:

In the present study we have obtained a novel formula to predict the insertion depth of LDLT. Currently we are conducting a verification study on a larger sample size to attest its validity. However at this stage and till the results are released we cannot judge on it. We believe time will tell about the validity of our formula for our patients.

Predicting Optimal Insertion Depth of a Left-sided Double-Lumen Endobronchial Tube

OBJECTIVE

Appropriate placement of the double-lumen endobronchial tube (DLT) is essential for one-lung ventilation. Several formulae based on body height (BH) have been used for estimating the optimal insertion depth of a left-sided DLT. In this study, the authors examined the following 5 formulae for accuracy of prediction: 0.11×BH+10.53 (cm) from Brodsky et al(1); 0.15×BH+3.96 (cm) from Bahk and Oh(2); 0.148×BH+3.8 (cm) from Chow et al;(3) 0.1×BH+12.5 (cm) from Takita et al(4); and 0.1977×BH - 4.2423 (cm) (authors' formula).

DESIGN

Single-center, retrospective, observational study.

SETTING

University hospital.

PARTICIPANTS

Anesthetic records of patients older than 20 years who received one-lung ventilation using a left-sided DLT were included.

INTERVENTIONS

The patients' sex, age, body weight, BH, and the final correct insertion depth of the left-sided DLT after fiberscope verification were recorded. Linear regression and correlation were used to analyze the data.

MEASUREMENTS AND MAIN RESULTS

One hundred seventy anesthetic records were analyzed. The insertion depth was distributed normally in 4 groups with different BH intervals. The correlations between the correct insertion depth and all the lengths calculated using each formula were significant (p<0.001), with a similar high coefficient of determination (r = 0.809). The regression line derived from the authors' formula-0.1977×BH - 4.2423 (cm)-showed the most accuracy in predicting the correct insertion depth.

CONCLUSIONS

The height-based formula of 170 - 29.5 - 5 - 1 (the insertion depth is 29.5 cm for patients who are 170 cm tall, and the insertion length is increased or decreased by 1 cm for every 5 cm increase or decrease in BH) modified by the equation of 0.1977×BH - 4.2423 is a useful tool to predict the optimal insertion depth in initially blind left-sided DLT insertion.

Optimal depth of insertion of left-sided double-lumen endobronchial tubes cannot be predicted from body height in below average-sized adult patients

BACKGROUND AND OBJECTIVE

The optimal depth of insertion of left-sided double-lumen endobronchial tubes is strongly correlated with body height in average-sized adults. However, this relationship has not been studied in below average-sized adult patients. We investigated whether or not there is a clinically useful relationship in below average-sized adult patients.

METHODS

One hundred and ninety six consecutive adult patients undergoing thoracic surgery under one-lung anaesthesia (body height < or = 155 cm) were included in this study. Left-sided double-lumen tubes were inserted under the guidance of a fibre-optic bronchoscope. Optimal depth was defined as the proximal surface of the bronchial cuff positioned just below the carina.

RESULTS

There was a statistically significant positive correlation between body height and the optimal depth of insertion (r = 0.61, P < 0.0001); however, the correlation coefficient was low. The actual optimal depth of insertion of one patient was even 4.5 cm shorter than that obtained from the equation.

CONCLUSION

Although there was a statistically significant correlation between body height and the optimal depth of insertion of left sided double lumen tubes in adult patients of short stature (< or = 155 cm), clinical application of the equation is not warranted and these tubes should be inserted under direct vision with a fibre-optic bronchoscope.

Dimensions of double-lumen tracheobronchial tubes

The diameter of the left main bronchus is the determining dimension when selecting the size of a left tracheobronchial (double-lumen) tube for lung separation. However, this information is not given by any manufacturer, either on the tube or in the package insert. This paper describes the lengths and diameters of the deflated bronchial cuff segment of left tracheobronchial tubes in common use. One hundred and seventy-one left tracheobronchial tubes ranging in size from 28 to 41 nominal French gauge from four manufacturers were measured. There was wide variation between tubes of the same nominal size from the same manufacturer. For tubes of the same size from the same manufacturer, the diameter of the segment with the deflated bronchial cuff varied by more than 1 mm in diameter in some instances. The diameter of the bronchial cuff segment did not consistently decrease as the nominal size decreased even for the same manufacturer. There was major overlap in diameters of the bronchial segments between Fr 41, Fr 39, and Fr 37 tubes from most manufacturers, so that some of the Fr 39 tubes have a bronchial cuff segment diameter as much as 0.5 mm larger than the Fr 41 tube. It is concluded that the current French gauge markings on left tracheobronchial tubes are of very limited value in determining the appropriate size to be selected for a patient. More accurate and consistent dimensions of tracheobronchial tubes are required to improve clinical selection.