Comparison of Double Lumen Tube Placement Techniques: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Double Lumen Tube Placement Techniques (NCT02495259), a randomized na study. The primary outcome is Mean Time to Place the Double-lumen Endobronchial Tube.

2. Clinical Question

3. Trial Design

The registry describes a randomized, single-masked, parallel-group study sponsored by Emory University. It lists the phase as not applicable. The planned comparison involved three approaches to double-lumen endobronchial tube placement: a ZU-bend stylet with GlideScope, a GlideScope with a GlideRite stylet, and a Macintosh blade with a regular double-lumen tube stylet. The masking designation is recorded as single, but which participants or study personnel were masked is not reported in the registry record.

The study concerned patients scheduled for thoracic surgery when the surgeon requested lung isolation. The brief summary frames the purpose as comparing the three methods of placement. The registry enrollment is 19. The primary completion date is 2017-07-27, and the study status is terminated. The start date is recorded as 2015-07. The reason for termination and whether it was related to recruitment, safety, logistics, or another consideration are not reported in the registry record.

The primary outcome was mean time to place the double-lumen endobronchial tube, measured in seconds during laryngoscope placement, up to 120 seconds. The registry also names success at the first endobronchial intubation attempt, difficulty of intubation, cases with complications, cases of voice change, and throat pain as secondary outcomes. Results for those outcomes are not reported in the registry record. The registry does not report the allocation ratio, randomization sequence method, concealment procedures, or the identity of the masked party. It also does not report a protocol-level statistical analysis plan or the reason enrollment ended at the recorded level.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Mean Time to Place the Double-lumen Endobronchial Tube, measured over during laryngoscope placement, up to 120 seconds.

The primary endpoint is the time taken for successful intubation with a double-lumen endobronchial tube. The anesthetist recorded the interval from the laryngoscope reaching the patient's lips to the first detection of end-tidal carbon dioxide. The registry describes the endpoint timeframe as during laryngoscope placement, up to 120 seconds, and expresses the measurement in seconds. A longer recorded duration represents more time to successful intubation according to the endpoint description.

The endpoint is a continuous measurement, and the registry reports a mean and standard deviation for each arm. In general, time-based procedural outcomes can describe how long a task takes, while the mean gives the average and the standard deviation describes the spread of individual observations around that average. These summaries do not by themselves show whether differences between arms are statistically distinguishable from chance variation, nor do they describe every aspect of airway management or the patient's subsequent course.

The registry does not report how unsuccessful attempts, repeated attempts, or measurements reaching the stated limit were handled in the primary endpoint analysis. It also does not report whether timing was independently verified or whether the anesthetists knew which technique was being used. Such details affect how a procedural time should be interpreted, but they cannot be inferred from the endpoint definition alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

In general, a randomized parallel-group trial assigns participants to one of several approaches and compares outcomes between groups. Random assignment can reduce systematic differences in participant characteristics, on average, but it does not guarantee that groups are balanced in a small study. The registry identifies this study as randomized and parallel. It does not report the sequence-generation method, allocation concealment, or the allocation ratio, so those implementation details cannot be evaluated from the registry record.

What does a mean and standard deviation describe?

In general, the mean is the arithmetic average of the recorded values. The standard deviation describes how dispersed the individual measurements are around the mean. The posted primary endpoint summaries use this format: the ZU-bend stylet with GlideScope arm has a mean of 111 seconds and standard deviation of 44.9; the GlideScope with GlideRite stylet arm has a mean of 54 seconds and standard deviation of 13.1; and the Macintosh blade with regular double-lumen tube stylet arm has a mean of 55 seconds and standard deviation of 17.5. The posted endpoint sample sizes are 7, 3, and 8. These descriptions do not reveal the full distribution of observed times, whether there were unusual values, or how individual measurements were handled.

Why are uncertainty estimates important?

In general, an estimate from a sample is uncertain because a different set of participants could produce a different estimate. A confidence interval communicates a range of values compatible with the data and the statistical procedure used to construct it. A hypothesis test provides another way to assess compatibility with a specified null hypothesis, commonly by reporting a p-value. Neither a confidence interval nor a p-value is reported for the primary endpoint in this registry record. Without them, the observed means should not be treated as proof that one method has a reliably shorter mean time than another.

General comparisons of means may use methods that rely on distributional assumptions, or methods that account for unequal variability or other features of the data. Which approach is suitable depends on the design, data distribution, and analysis plan. Over-dispersion, broadly, means that variability is greater than a model expects; ignoring it can make uncertainty look too small. The registry does not report a primary comparison method, distributional assessment, or variance model. No particular method should therefore be attributed to the investigators.

What can the posted summaries support?

The arm-level means and standard deviations support a descriptive account of the recorded endpoint. They do not provide an adjusted estimate, a pairwise contrast, or an uncertainty interval. The registry reports zero analysis entries and indicates that values are missing or not estimable for a two-arm comparison of the continuous endpoint. The absence of a posted comparison is not evidence that the arm means are equal; it means that the registry record does not provide an inferential result for those comparisons.

Recalculated analyses, when available, are simple unadjusted calculations from posted summary statistics. No recalculated primary comparison is reported for this endpoint. More generally, a calculation based on summary statistics would not replace a prespecified sponsor analysis, particularly if the analysis depended on participant-level data, covariate adjustment, or rules for handling unsuccessful attempts. The registry does not report those details.

How should planning calculations be read?

In general, a sample-size calculation estimates the amount of information a future study would need under stated assumptions. A planning illustration based on an observed effect is not observed power and does not show that the completed study had adequate power. The stated planning assumptions for the illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. These assumptions describe planning calculations, not the design or analysis actually used for this trial. The registry does not report the trial's own sample-size justification, target enrollment rationale, or planned power.

All such illustrations depend on assumptions about the expected effect and variability. If the observed effect comes from a small sample, it can be an unstable basis for forecasting another study. A planning result does not repair the lack of a reported inferential comparison in the completed trial, and it should not be interpreted as evidence that an effect was detected. The registry record does not report interim analyses or a statistical stopping rule.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("ZU-bend Stylet With GlideScope Technique", "GlideScope With the GlideRite Stylet", "Macintosh Blade and a Regular DLT Stylet")
n   <- c(7, 3, 8)
m   <- c(111, 54, 55)
sp  <- c(44.9, 13.1, 17.5)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  ZU-bend Stylet With GlideScope Technique  7  111.000  44.900  69.474  152.526
CARM  GlideScope With the GlideRite Stylet  3  54.000  13.100  21.458  86.542
CARM  Macintosh Blade and a Regular DLT Stylet  8  55.000  17.500  40.370  69.630

11. Multiplicity, Missing Data and Analysis Populations

The registry names five secondary outcomes: success at the first endobronchial intubation attempt, difficulty of intubation, cases with complications, cases of voice change, and throat pain. Their results are not reported in the registry record. The record also lists six outcome measures overall, but does not explain the relationship between that total and the named primary and secondary outcomes. No multiplicity adjustment, hierarchy of hypotheses, or strategy for selecting outcomes for formal testing is reported. In general, testing several outcomes can increase the chance of finding an apparently notable result by chance; whether and how to address that depends on a prespecified analysis plan.

The registry does not report missing-data counts or reasons for missingness for the primary endpoint. It gives primary endpoint sample sizes of 7, 3, and 8 across the arms, while enrollment is recorded as 19. The record does not explain this accounting. It does not specify whether the primary analysis included all randomized participants, only those with successful intubation, or another analysis population. It also does not describe how failed attempts, values at the stated time limit, or missing timing observations were handled.

These omissions matter because the observed summaries may depend on which participants and measurements were available for analysis. The registry does not report an intention-to-treat analysis, a per-protocol analysis, or sensitivity analyses for missing data. The single-masking designation is recorded, but the masked party is not identified. These reporting gaps limit assessment of outcome selection, analysis populations, and the robustness of the endpoint results.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists zero serious adverse events in each arm and zero deaths. It also lists zero other adverse events in each arm. The recorded serious-event and other-event denominators are 7 for the ZU-bend stylet with GlideScope technique, 4 for GlideScope with the GlideRite stylet, and 8 for the Macintosh blade with a regular double-lumen tube stylet. No serious adverse-event terms are listed.

These entries describe what was recorded in the registry; they should not be read as proof that the techniques carry no risk. With limited recorded group sizes, an absence of observed events cannot establish that an event is impossible or estimate its frequency precisely. The safety denominators also differ from the primary endpoint sample size for the GlideScope with GlideRite stylet arm, which is listed as 3 rather than 4. The registry does not explain this difference, define the safety observation period, or describe how adverse events were collected. The listed zero counts therefore provide a narrow account of reported events, not a comprehensive safety comparison.

13. What the Result Does, and Does Not, Mean

The result is a set of descriptive primary-endpoint summaries for three intubation techniques in a randomized, parallel-group study. The recorded mean time was 111 seconds in the ZU-bend stylet with GlideScope arm, 54 seconds in the GlideScope with GlideRite stylet arm, and 55 seconds in the Macintosh blade and regular double-lumen tube stylet arm. The accompanying standard deviations and endpoint sample sizes describe the observed data, but the registry does not report confidence intervals, p-values, or a formal comparison.

Accordingly, the posted results do not establish whether any observed separation in mean times is larger than would be expected from sampling variability. They also do not demonstrate equivalence or no difference among the approaches. A lack of a reported inferential result is not a finding that the methods perform identically. The record does not provide enough information to quantify uncertainty in the comparisons or to assess how missing observations may have influenced the means.

The primary endpoint concerns elapsed time to first end-tidal carbon dioxide detection under the registry's definition. It does not, on its own, measure every aspect of successful airway management, patient experience, or subsequent clinical course. Although the registry lists first-attempt success, intubation difficulty, complications, voice change, and throat pain as secondary outcomes, their results are not reported in the registry record. The safety entries report no recorded adverse events in the listed denominators, but do not establish absence of risk.

The trial is terminated, and the record does not report why. Enrollment is recorded as 19, while the primary endpoint group sizes are 7, 3, and 8; the record does not reconcile these figures. Taken together, the evidence supports a limited description of the posted times and event counts. It does not support a broad conclusion about comparative effectiveness, safety, or performance in settings beyond the described thoracic-surgery population.

14. Why This Trial Matters Statistically

This trial illustrates why a randomized label and arm-level outcome summaries are not enough to establish a precise comparative result. Randomization is an important design feature, but interpretation also requires the outcome data, a defined analysis population, an analysis method, and an account of uncertainty. Here, the registry gives means, standard deviations, and group sizes for the primary endpoint, but no posted inferential comparison. Readers can describe the recorded values, yet cannot use the registry results to determine the precision of differences between techniques.

The study also highlights the distinction between a procedural measure and a broader clinical outcome. Time from laryngoscope placement to first end-tidal carbon dioxide detection is a clearly stated continuous measure. It can summarize one aspect of the intubation process, but the named secondary outcomes would address other aspects, including first-attempt success and complications. Their results are not reported in the registry record, leaving the primary time summaries without that broader outcome context.

The reported endpoint group sizes are limited, particularly for the GlideScope with GlideRite stylet arm, and enrollment does not reconcile directly with those endpoint counts in the record. Small groups generally yield less precise estimates, while unreported missing-data and analysis-population details make it harder to assess representativeness. This is a useful example of how completeness of reporting affects statistical interpretation: descriptive results can be informative, but they do not answer every comparative question a randomized study raises.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this record constrain interpretation. The study status is terminated, but the reason for termination is not reported in the registry record. Enrollment is recorded as 19, whereas the primary endpoint sample sizes are 7, 3, and 8; the record does not explain the relationship between these figures or whether any enrolled participants lacked endpoint data. The safety denominator for the GlideScope with GlideRite stylet is 4, compared with a primary endpoint sample size of 3 for that arm, and this difference is also unexplained.

The primary outcome is reported only as arm-level means and standard deviations. There are no posted confidence intervals, p-values, adjusted estimates, or formal pairwise comparisons. The registry lists no analysis entries and states that values are missing or not estimable for a two-arm comparison of the continuous endpoint. It does not report the statistical analysis plan, the randomization procedure, the allocation ratio, or the identity of the masked party.

The endpoint definition does not explain how failed or repeated attempts, observations at the stated time limit, or missing timing measurements were handled. The record does not identify the primary analysis population or provide sensitivity analyses. Although five secondary outcomes are named, their results are not reported in the registry record, and no approach to multiplicity is described. The adverse-event listing reports zero events in its denominators but does not provide an observation period or event-collection detail. These omissions prevent a fuller assessment of data completeness, analysis choices, and the scope of the reported findings.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Comparison of Double Lumen Tube Placement Techniques — NCT02495259.
• Registry record last updated 2018-07-27; status last verified 2018-06.
• Results first posted 2018-07-27.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT02495259 is a randomized, single-masked, parallel-group study sponsored by Emory University, listed as not applicable for phase and terminated. Its stated purpose was to compare three methods for double-lumen endobronchial tube placement in patients scheduled for thoracic surgery requiring lung isolation. The registry enrollment is 19.

The primary endpoint is mean time to successful tube placement, recorded from laryngoscope placement at the lips to first end-tidal carbon dioxide detection, in seconds. Posted arm means are 111, 54, and 55 seconds, with standard deviations of 44.9, 13.1, and 17.5 and endpoint sample sizes of 7, 3, and 8. No formal primary comparison is reported. Five secondary outcomes are named, but their results are not reported in the registry record. The registry lists zero serious adverse events, zero other adverse events, and zero deaths in the stated safety denominators.