Open Access Original
Article

DOI: 10.7759/cureus.51895

Appropriate Endotracheal Tube Position for
Percutaneous Dilatational Tracheostomy: A
Single-Center Observational Study

Review began 12/17/2023
Review ended 01/04/2024

Takahiro Michishita 1 , Naoya Suzuki 1 , Takeru Abe 2 , Kento Nakajima 2 , Masayasu Gakumazawa 1 , Tomoki
Doi 1 , Ichiro Takeuchi 2

Published 01/08/2024© Copyright 2024
Michishita et al. This is an open accessarticle distributed under the terms of theCreative Commons Attribution License CC-

1. Department of Emergency Medicine, Yokosuka Kyosai Hospital, Yokosuka, JPN 2. Department of Emergency
Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, JPN

BY 4.0., which permits unrestricted use,
distribution, and reproduction in any
medium, provided the original author andCorresponding author: Takahiro Michishita, takatakkatakahiro@gmail.com

source are credited.

Abstract
Aim
This study aimed to investigate the appropriate endotracheal tube (ETT) position during percutaneous
dilatational tracheostomy (PDT).

Methods
This single-center observational study included hospitalized patients who underwent surgical tracheostomy(ST) between August 2021 and October 2022. During ST, the trachea was opened, and the ETT was pulled out
visually. It stopped when the ETT was no longer visible, and the tracheostomy tube was placed in the
trachea. The ETT position was measured by considering the ETT position during ST to be the appropriate
position during PDT. The correlation between the measured ETT position and patient characteristics wasevaluated. A prediction equation for the ETT position was derived from the derivation group, and validationof the prediction equation was evaluated by the validation group.

Results
Forty-six and 15 patients were in the derivation and validation groups, respectively. Weight, duration of
intubation, and in-hospital mortality were significantly different between the two groups. The measured
ETT position correlated with body height (r=0.60, p<0.001) and sex (r=0.45, p=0.002), while the ETT position
before ST showed a weak correlation (r=0.34, p=0.020). The predicted and measured values in the validationgroup correlated with each other (r=0.58, p=0.024).

Conclusion
The appropriate ETT position for PDT correlates with body height, and the equation "body height×0.1120.323 cm" was derived. This predictive equation may be useful as a guide for ETT positioning during PDT
puncture.

Categories: Cardiac/Thoracic/Vascular Surgery, Emergency Medicine, Otolaryngology
Keywords: surgical tracheostomy, prediction equation, percutaneous dilatational tracheostomy, endotracheal tube
position, endotracheal tube

Introduction
Tracheostomy is one of the most frequently performed surgical procedures in the intensive care unit (ICU)
on patients in whom extubation is difficult or who have been intubated for a long time [1-3]. There are two
types of tracheostomies: surgical tracheostomy (ST) and percutaneous dilatational tracheostomy (PDT). ST
was first performed in 1909 by surgically peeling the skin down to the anterior surface of the first or second
tracheal cartilage rings, opening the trachea, and inserting a tracheostomy tube under direct vision [4]. PDT
was first described in 1985, and although there are various methods for PDT, the modified Ciaglia method
developed in 1998, in which a single dilator is used to expand the wound in a single step, is the mostfrequently used [5,6]. The prevalence of PDT varies regionally, with PDT accounting for 86% oftracheostomies performed in Germany and 97% in the United Kingdom; in France, PDT represents only 27%
of all the tracheostomies performed [7-9]. PDT is preferred over ST throughout Europe because it requires
less operative time and has a similar risk of surgery-related complications compared to ST; PDT is the first
choice for tracheostomy in many countries [6,10,11].
PDT is commonly performed by puncturing the first or second tracheal cartilage, dilating, and inserting a
tracheostomy tube while monitoring each step of PDT with a bronchoscope [1]. Bronchoscopy is used in
69.2% of all PDT procedures [6]. During the puncture, the endotracheal tube (ETT) position should be
adjusted so that the puncture position and the ETT do not overlap. Although a method of puncturing the

How to cite this article
Michishita T, Suzuki N, Abe T, et al. (January 08, 2024) Appropriate Endotracheal Tube Position for Percutaneous Dilatational Tracheostomy: A
Single-Center Observational Study. Cureus 16(1): e51895. DOI 10.7759/cureus.51895

anterior surface of the trachea with the entire ETT without daring to move the ETT to protect the posteriortracheal wall has been reported [12], this method of adjusting the ETT position and puncturing is commonlyused.
If the ETT position is deep during PDT, the ETT will be present under the puncture needle, leading tosurgical errors and accidental puncture of the ETT and bronchoscope. Conversely, a shallow ETT position
increases the risk of accidental extubation during tracheostomy. Accidental puncture of the ETT is thesecond most common complication of PDT after hemorrhage [6] and accidental extubation during surgery;breakage of the ETT cuff has also been reported [6,13,14]. There are hybrid methods of PDT and ST in which
the subcutaneous tissue is removed from the front of the trachea, and the ETT is pulled out using the lightsource of the bronchoscope [15]. The hybrid method requires more time to remove the subcutaneous tissue
to the front of the trachea, reducing the advantage of the shorter operative time of PDT [10]. Knowing theappropriate ETT position during PDT may lead to safer and shorter PDT. However, an appropriate ETT
position and how much ETT position should be adjusted for PDT puncture have not been reported yet. This
study aimed to investigate the appropriate ETT position for PDT using ST.

Materials And Methods
Research design
This was a retrospective single-center observational study conducted at Yokosuka Kyosai Hospital in
Yokosuka, Japan, from August 2021 to October 2022 (approval number: 21-47). Patients who underwent ST
in the emergency department were included in the study. The derivation group was studied from August2021 to May 2022 and the validation group from June 2022 to October 2022. The ETT position was measured
in the median of the portal teeth when ST was performed. The measured ETT position was used as theoutcome. Data on age (years), sex (male or female), body height (cm), weight (kg), length of hospital stay(days), length of ICU stay (days), length of intubation (days), Sequential Organ Failure Assessment (SOFA)
score at admission, Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II score atadmission, in-hospital death, ETT tip position from the tracheal bifurcation on chest radiographs (cm), ETT
position before ST (cm), diseases leading to tracheostomy, and tracheostomy complications were alsocollected from the electronic medical records. A prediction equation for ETT position was derived in thederivation group, and the prediction equation was validated using the validation group.

ETT position measurement method
During ST, the subcutaneous skin was peeled, the trachea was opened, the ETT was pulled out till it was nolonger visible, and the tracheostomy tube was placed into the trachea (Figure 1). The ETT position at thetime of tracheostomy tube insertion during ST is also considered appropriate for PDT puncture. ST cases
were collected by measuring the above ETT position in terms of the length from the tip of the tube to themedian of the portal teeth.

2024 Michishita et al. Cureus 16(1): e51895. DOI 10.7759/cureus.51895

2 of 9FIGURE 1: Method of ETT position measurement during ST
A: The subcutaneous skin is peeled off and the trachea is opened.
B: The ETT is pulled out such that the tip of the tube is no longer visible.
From the Ciaglia Blue Rhino IFU images, Cook Medical. Copyright © Cook Medical. Reprinted and partiallymodified with permission from Cook Medical.
ETT: endotracheal tube; ST: surgical tracheostomy

Statistical analysis
Categorical data are expressed as numbers (percentages), and continuous variables are expressed as
medians (interquartile range (IQR)) unless otherwise stated. Categorical data were compared using Pearson's
chi-squared test or Fisher's direct probability test for the derivation and validation groups, and continuous
variables were compared using the Student's t-test or Mann-Whitney U test. A two-sided p<0.05 value wasconsidered statistically significant. The relationship between the measured ETT position and patient
background was examined using Spearman's forward-phase relation number. A single regression analysis
was performed on the parameters with the highest correlation coefficients in the derivation group to obtaina predictive model for the ETT position. The correlation between the predicted and measured values derived
from the prediction equation obtained by the validation group was evaluated using Spearman's forwardphase relation number. All statistical analyses were performed using EZR (Saitama Medical Center, Jichi
Medical University, Saitama, Japan), a graphical user interface for R (The R Foundation for StatisticalComputing, Vienna, Austria). More precisely, it is a modified version of the R commander designed to add
statistical functions frequently used in biostatistics [16].

Results
There were 61 cases in total: 46 in the derivation group and 15 in the validation group. Table 1 summarizes
the clinical characteristics and measured ETT positions of the 61 patients in the two groups. Age (p=0.519),
sex (p=0.510), body height (p=0.306), length of hospital stay (p=0.487), length of ICU stay (p=0.979), SOFA
score at admission (p=0.113), APACHE II score at admission (p=0.526), ETT tip position from the tracheal
bifurcation (p=0.596), and ETT position before ST (p=0.368) were not significantly different between the twogroups. The predominant differences between the two groups' median (IQR) or frequency (percentage) were
weight (62.1 (54.2-73.2) kg vs. 51.9 (47.1-59.7) kg, p=0.008), length of intubation (6 (4-9) days vs. 10 (6.514.5) days, p=0.013), and in-hospital death (17 (37%) vs. 1 (6.7%), p=0.047), with a trend toward heavier
weight, shorter intubation days, and higher in-hospital mortality in the derivation group and with no casesof tracheostomy complications in either group. Among the diseases causing tracheostomy, coronavirus
disease 2019 (COVID-19) was more common in the derivation group (43.5% vs. 0%, p=0.001), and trauma
was more common in the validation group (40% vs. 6.5%, p=0.005). Among the COVID-19 cases, there were
12 in-hospital deaths, with a median weight of 70.2 (61.1-80.8) kg and a median length of intubation of 5.5(4-6.25) days. The median measured ETT position was 18 cm in both groups (IQR 17-19 cm in the derivationgroup and 16.5-18 cm in the validation group), and there was no significant difference between the twogroups (p=0.163).

2024 Michishita et al. Cureus 16(1): e51895. DOI 10.7759/cureus.51895

3 of 9

Derivation group (n=46)

Validation group (n=15)

p-value

Age, median (IQR), year69

(58.25-77.75)

76(42-85)0.519

Male sex, n (%)

35(76.1)

10(66.7)

0.510

Body height, median (IQR), cm

165.5(160.7-170)

160(156.5-172.5)

0.306

Weight, median (IQR), kg

62.1(54.2-73.2)

51.9(47.1-59.7)

0.008

Length of hospital stay, median (IQR), days

44

(29-75)49(37.25-62.5)

0.487

Length of ICU stay, median (IQR), days

21.5

(13-31.25)

21(16.25-24.75)

0.979

Length of intubation, median (IQR), days

6

(4-9)

10

(6.5-14.5)

0.013

SOFA score, median (IQR)

9(6-10)

10(8-11.5)

0.113

APACHE II score, median (IQR)

27(22-31)

28(23-32)0.526

In-hospital death, n (%)

17

(37)

1

(6.7)

0.047

ETT tip position from tracheal bifurcation, median (IQR), cm

3.9(2.7-4.7)

3.6(2.7-4.7)

0.596

ETT position before ST, median (IQR), cm

24(23-25)23(22-26.5)

0.368

Measured ETT position, median (IQR), cm

18(17-19)18(16.5-18)

0.163

COVID-1920(43.5)

0

(0)

0.001

Neuromuscular disease7(15.2)

0

(0)

0.178

CPA

4

(8.7)

3

(20)

0.348

Respiratory disease

4

(8.7)

3

(20)

0.348

Trauma

3

(6.5)

6

(40)

0.005

Airway assurance

3

(6.5)

2

(13.3)

0.589

Heart disease

3

(6.5)

0

(0)

0.569

Burn

2

(4.3)

1

(6.7)

1.000

Diseases leading to tracheostomy, n (%)

TABLE 1: Outcome and clinical characteristics
IQR: interquartile range; ICU: intensive care unit; SOFA: Sequential Organ Failure Assessment; APACHE: Acute Physiologic Assessment and Chronic
Health Evaluation; ETT: endotracheal tube; ST: surgical tracheostomy; COVID-19: coronavirus disease 2019; CPA: cardiopulmonary arrest

Figure 2 summarizes the scatter plots of the measured ETT position, body height, sex, ETT position before
ST, and weight in the derivation group. Correlations were found for body height (r=0.60, p<0.001) and sex(r=0.45, p=0.002), whereas ETT position before ST (r=0.34, p=0.020) showed a weak correlation. Weight
showed no correlation (r=0.07, p=0.651). Single regression analysis was performed based on body height,
which had the highest correlation coefficient, to derive a prediction equation for the appropriate ETT
position at PDT as follows: appropriate ETT position at PDT=body height×0.112-0.323 cm (p<0.001, Rsquared: 0.33, adjusted R-squared: 0.31). For example, if the patient's height were 170 cm, this prediction
equation would indicate that the appropriate ETT position for PDT puncture would be 18.7 cm.

2024 Michishita et al. Cureus 16(1): e51895. DOI 10.7759/cureus.51895

4 of 9FIGURE 2: Correlation between patient characteristics and measured
ETT position in the derivation group
ETT: endotracheal tube; ST: surgical tracheostomy

The scatter plots of the predicted and measured ETT positions in the validation group are summarized in
Figure 3. The predicted and measured values correlated (r=0.58, p=0.024).

2024 Michishita et al. Cureus 16(1): e51895. DOI 10.7759/cureus.51895

5 of 9FIGURE 3: Scatter plots of the predicted and measured values in thevalidation group
ETT: endotracheal tube

Discussion
This study revealed the following two points: the equation "appropriate ETT position at PDT=bodyheight×0.112-0.323 cm" was derived, and the values predicted using this equation correlated with themeasured values in the validation group.
In this study, we examined the correlation between the measured ETT position and the patient's
background, including sex, body height, weight, and ETT position before ST. We found that body height
showed the strongest correlation (r=0.6, p<0.001). The strongest correlation between body height and theability to predict ETT position from body height is consistent with Morgan's equation (body height/10+5cm), which is a prediction equation for ETT position at intubation [17]. Sex also had a strong correlation(r=0.45, p=0.002) in this study; however, sex is a confounding factor for body height, which may have givenrise to the correlation [18]. Conversely, the ETT position before ST was only weakly correlated (r=0.34,
p=0.020). In one study, 12% of chest radiographs taken in the ICU showed abnormal ETT position [19]. In
this study as well, after reviewing the chest radiographs of each case, the length of the ETT tip position fromthe tracheal bifurcation varied from case to case (IQR, 2.7-4.7 cm), suggesting that the inconsistent ETT
position resulted in a weak correlation.
The appropriate ETT position during PDT ranges from just above the puncture needle (Figure 4A) to theposition where the cuff, which prevents accidental extubation, rests on the vocal cords (Figure 4C). This
study measured the ETT position directly above the puncture needle, and the formula "body height×0.1120.323 cm" was derived.

2024 Michishita et al. Cureus 16(1): e51895. DOI 10.7759/cureus.51895

6 of 9FIGURE 4: ETT position at puncture in PDT
A: Appropriate ETT position.
B: Deep ETT position.
C: Shallow ETT position.
From the Ciaglia Blue Rhino IFU images, Cook Medical. Copyright © Cook Medical. Reprinted and partiallymodified with permission from Cook Medical.
ETT: endotracheal tube; PDT: percutaneous dilatational tracheostomy

While comparing the two groups, the weight was heavier (p=0.008), the length of intubation was shorter(p=0.013), and in-hospital mortality was higher in the derivation group (p=0.047) compared to the validationgroup. The collection period for the derivation group was August 2021 to May 2022 during the COVID-19
pandemic and thus showed a higher rate of COVID-19 as the disease requiring tracheostomy (p=0.001).
Obesity is a risk factor for severe COVID-19 [20,21], and the disease has a high mortality rate. The mortality
rate for patients intubated with COVID-19 has been reported to be 47.3% [22]. In this study, the medianweight of patients with COVID-19 was 70.2 (61.1-80.8) kg, and 12 of the 17 in-hospital deaths in thederivation group were due to COVID-19 (70.6%). When COVID-19 became severe enough to require
intubation, early extubation was judged to be difficult, and tracheostomy was performed early in our
hospital to promote rehabilitation (median length of intubation in COVID-19 cases: 5.5 (4-6.25) days). The
COVID-19 pandemic may have caused the difference in predominance between the two groups.
The correlation coefficient between the predicted and measured values in the validation group was r=0.58,
close to the correlation coefficient between the body height and measured ETT position in the derivationgroup (r=0.60). Although there were differences between the derivation and validation groups in terms of
the length of intubation, in-hospital death, and tracheostomy-related diseases, there was no difference inthe accuracy of the prediction equation between the two groups. The prediction equation presented in thisstudy predicts an appropriate ETT position with similar accuracy, even when there are differences in patientgroups, demonstrating the generality of this prediction equation. Predicting the appropriate ETT position
based on body height before performing PDT could prevent accidental puncture of the ETT and accidental
extubation, which may be useful for safe and short-term PDT. However, this study did not examine theextent to which PDT complications could be reduced or the time saved using this prediction equation,
warranting further studies.

Limitations
This study had several limitations. First, this was a retrospective single-center observational study, which
limited the external validity of the findings because of the possibility of selection bias. Second, whether theappropriate ETT position is the same for PDT and ST is unclear. Although this study was conductedassuming that the appropriate ETT position is the same for PDT and ST, it is uncertain whether thisassumption is correct. Third, this study examined the ETT position directly above the puncture needle(Figure 4A) but did not examine the position of the ETT cuff over the vocal cords (Figure 4C), which poses arisk of accidental extubation. Although there may be a range of appropriate ETT positions, the present study
did not examine this range.

Conclusions
This study aimed to investigate the appropriate ETT position for PDT using ST. Our findings showed that theappropriate ETT position for PDT correlates with body height and sex. Single regression analysis was
performed based on body height, which had the highest correlation coefficient, and the equation "bodyheight×0.112-0.323 cm" was derived. The values predicted using this equation correlated with the measured
values in the validation group. This predictive equation may be useful as a guide to the appropriate ETT2024 Michishita et al. Cureus 16(1): e51895. DOI 10.7759/cureus.51895

7 of 9position during PDT puncture.

Additional Information
Author Contributions
All authors have reviewed the final version to be published and agreed to be accountable for all aspects of thework.
Concept and design: Takahiro Michishita, Naoya Suzuki, Takeru Abe, Tomoki Doi
Acquisition, analysis, or interpretation of data: Takahiro Michishita, Naoya Suzuki, Takeru Abe,
Masayasu Gakumazawa, Tomoki Doi, Kento Nakajima, Ichiro Takeuchi
Drafting of the manuscript: Takahiro Michishita, Naoya Suzuki, Takeru Abe
Critical review of the manuscript for important intellectual content: Takahiro Michishita, Naoya
Suzuki, Takeru Abe, Masayasu Gakumazawa, Tomoki Doi, Kento Nakajima, Ichiro Takeuchi
Supervision: Takahiro Michishita, Naoya Suzuki, Takeru Abe, Masayasu Gakumazawa, Tomoki Doi, Kento
Nakajima, Ichiro Takeuchi

Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. The Institutional Review
Board (IRB) of the Yokosuka Kyosai Hospital issued approval 21-47. The research was conducted inaccordance with the Declaration of Helsinki. Animal subjects: All authors have confirmed that this study
did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform
disclosure form, all authors declare the following: Payment/services info: All authors have declared that nofinancial support was received from any organization for the submitted work. Financial relationships: All
authors have declared that they have no financial relationships at present or within the previous three years
with any organizations that might have an interest in the submitted work. Other relationships: All authors
have declared that there are no other relationships or activities that could appear to have influenced thesubmitted work.

Acknowledgements
We would like to thank Kaede Fujii, MD, Saori Mizukami, MD, Shota Yamamoto, MD, Risako Matsuo, MD,
Kurumi Mori, MD, Taichi Ito, MD, and Yusuke Kishimoto, MD, for helping us with the measurements of theETT position. We would also like to thank Editage (http://www.editage.jp) for English language editing.

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