"Neutral Head Position" and "Head-lift Position" for Orotracheal Intubation With "Trachway" Intubating Stylet in Adults: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for "Neutral Head Position" and "Head-lift Position" for Orotracheal Intubation With "Trachway" Intubating Stylet in Adults (NCT02578992), a randomized na study. The primary outcome is Intubation Time.

2. Clinical Question

The comparison concerns positioning within a particular intubation setup: both groups used the Trachway stylet and the same described chin-lift technique. It is not a comparison of different devices or of intubation with versus without a chin lift. The trial record identifies the study population as adults and lists difficult intubation as a condition, but does not report how that condition was defined or whether every enrolled participant had a documented history of difficulty.

The registry labels the study randomized and parallel. It does not describe the random sequence method, allocation concealment, or which people were masked. Those details matter when assessing whether the groups were comparable and whether measurements or care could have been influenced by knowledge of assignment. The posted information therefore frames a specific procedural question but does not fully establish the context in which participants were selected and assessed.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group study sponsored by Tri-Service General Hospital (TSGH). Its status is completed. The recorded start is 2014-12, and the primary completion is 2015-10. The registry lists enrollment of 130. The phase is recorded as NA, which does not provide a phase category for interpreting this procedural comparison.

Participants were assigned to a head-lift position or a neutral position. In the head-lift arm, a 7 cm high pillow was placed beneath the head while the head itself was described as neutral; intubation then used the Trachway stylet and a single-handed chin-lift technique. In the neutral arm, the head was placed in the neutral position and the same stylet and chin-lift technique were described. The registry classifies the overall model as parallel and the allocation as randomized.

The primary outcome record gives 62 participants for each arm. The registry does not explain how those outcome counts relate to the total enrollment of 130, including whether the difference reflects exclusions, unavailable measurements, or another accounting approach. It also does not report the analysis population definition, reasons for any participants not represented in the primary summaries, or the handling of missing measurements.

Although the study is labeled single-masked, the identity of the masked party is not reported in the registry record. Details of sequence generation, concealment, protocol deviations, and the planned statistical analysis are also not reported in the registry record. Random allocation is relevant to the credibility of an arm comparison, but the registry description alone is insufficient to assess how allocation was implemented or how masking was maintained.

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.

Before assignment: Patient denied to participated, equipment unavailable or malfunction, difficult mask ventilation were excluded .

Overall Study

Reasons for not completing this period:

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.

Population: age from 20-80

6. Primary Endpoint

The registry lists the primary outcome as Intubation Time, measured over from the intubating stylet touched the mouth to the capnogram shown, up to 30 seconds, and the sum of all attempts.

The primary endpoint is intubation time in seconds. The registry defines it as the interval from the moment the intubating stylet touched the mouth until a capnogram appeared. The stated timeframe says that timing was up to 30 seconds and that the sum of all attempts was used. An independent observer recorded the interval with a stopwatch.

Time is a direct measure of how long the described intubation process took under the trial conditions. It can capture procedural duration without relying on a participant’s recollection or a subjective rating. The endpoint’s definition is important: it starts at stylet contact, ends at the appearance of the capnogram, and includes all attempts, rather than measuring only a successful attempt or a narrower part of the procedure.

The registry reports the primary endpoint as a median with an interquartile range. A median describes the central value of the observed times, while the interquartile range describes the spread of the middle portion of those observations. These summaries can be useful when values are not well represented by a mean and standard deviation, but the registry does not report the full distribution, a confidence interval, or a formal inferential comparison for intubation time.

The posted median is 17.5 seconds (interquartile range 15.0 to 20.0) for the head-lift position and 21.0 seconds (interquartile range 19.0 to 23.25) for the neutral position. These are descriptive summaries. Without a reported statistical comparison or confidence interval for this endpoint, they do not by themselves establish the precision of the between-group difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The trial is described as randomized, single-masked, and parallel-group. Random allocation is a design approach intended to make baseline differences less systematically related to group assignment. In general, its value depends on how the sequence is generated and concealed; those implementation details are not reported in the registry record. The term single-masked indicates that masking was used in some form, but the registry does not identify who was masked or how masking was maintained. A parallel design means participants were assigned to one positioning group rather than crossing between both positions, according to the registry description.

What do the primary summaries say?

The primary outcome is reported using medians and interquartile ranges. A median is the central point in an ordered set of observations. The interquartile range describes the spread between the lower and upper quartiles, giving a view of the middle part of the data. These summaries are often useful when a distribution is skewed or contains unusually high or low observations. The registry does not state why this summary was selected, describe the distribution of times, or report a formal comparison of the medians.

The head-lift group has a reported median of 17.5 seconds and an interquartile range of 15.0 to 20.0; the neutral group has a median of 21.0 seconds and an interquartile range of 19.0 to 23.25. Each arm has 62 participants in the primary outcome record. These figures are descriptive. A formal comparison would require an analysis method suited to the endpoint and its distribution, together with an estimate of uncertainty. No such method or inferential result for the primary endpoint is reported in the registry record. The interquartile ranges are not confidence intervals for the group medians or their contrast.

How should the blood-pressure estimate be read?

Mean arterial pressure is reported as a mean with a standard deviation. The standard deviation describes variation among observations within a group; it is not the uncertainty of the estimated group mean. The posted means are 82.0 mmHg for neutral head position and 86.0 mmHg for head-lift position, with standard deviations of 14.0 and 12.0, respectively. The registry also reports a mean difference of 4.0 mmHg for head-lift versus neutral.

The 95% confidence interval for that difference is -0.590 to 8.59. General interpretation: a confidence interval gives a range of values compatible with the data and analysis under the assumptions used to construct it. It communicates uncertainty in an estimate rather than the range of individual participant outcomes. Since this interval includes zero, the posted result does not exclude no mean difference at the confidence level represented by the interval. Its breadth also indicates that the estimate is not highly precise. The registry does not report the prespecified analysis method or any adjusted estimate for this secondary outcome.

The unadjusted p-value is 0.088. General interpretation: a p-value measures how unusual data at least as incompatible with a specified null model would be, if that model and the analysis assumptions were correct. It is not the probability that the null model is true, and it does not quantify the size or practical importance of an effect. Because this is labeled unadjusted, it should be read without assuming correction for the examination of multiple outcomes or comparisons.

Why can over-dispersion matter?

General explanation: over-dispersion occurs when observed variability is greater than a statistical model expects. If a model underestimates variability, its standard errors may be too small and its confidence intervals too narrow, making evidence appear more precise than it is. For count outcomes, this issue can arise when observations vary more than a simple count model allows. The primary endpoint is a time measure summarized by a median and interquartile range, and the posted secondary comparison is a continuous mean difference; the registry does not report an over-dispersion analysis or indicate that this issue was assessed. No conclusion about over-dispersion should be inferred from the posted summaries.

What does the planning illustration represent?

The planning values associated with the secondary blood-pressure comparison are illustrations based on the observed effect, not the trial’s own design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation, and a normal approximation. For planning for 100% of the observed effect, the illustration gives 167 participants per arm for 80% power and 224 participants per arm for 90% power. For planning for 75% of the observed effect, it gives 297 participants per arm for 80% power and 397 participants per arm for 90% power. For planning for 50% of the observed effect, it gives 668 participants per arm for 80% power and 894 participants per arm for 90% power.

General explanation: such sample-size calculations describe how many participants a hypothetical future study might plan for under stated assumptions. They are not the observed power of the completed trial and do not show that the trial had or lacked a particular probability of detecting an effect. The registry does not report its own sample-size justification or the assumptions used when the trial was planned. Because the illustration uses an observed secondary effect, it should not be taken as a planning calculation for the primary intubation-time endpoint.

What analysis details are absent?

The registry record does not report the primary analysis method, a primary confidence interval, a formal primary p-value, a missing-data method, or an analysis-population definition. It also does not describe model assumptions, covariate adjustment, protocol deviations, or the handling of repeated or incomplete attempts beyond stating that the sum of all attempts contributed to intubation time. These omissions limit independent evaluation of how the posted estimates were obtained.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and three secondary outcomes. The primary endpoint is intubation time; the secondary outcomes are modified Cormack-Lehane grade, mean arterial pressure, and visual analog scale of sore throat. A multiplicity plan describing whether and how testing across these outcomes was controlled is not reported in the registry record. The posted mean arterial pressure p-value is unadjusted. Without a stated testing hierarchy or adjustment plan, the secondary p-value should not be treated as confirmatory evidence on its own.

The registry record does not report an analysis population definition, a missing-data plan, an imputation method, or reasons that outcome counts may differ from total enrollment. It records enrollment of 130 and primary outcome counts of 62 in each group, but does not explain the relationship between these figures. It is not possible from the record to determine whether all randomized participants were analyzed, whether any were excluded after allocation, or how unavailable measurements were handled.

The posted primary outcome summary uses 62 participants in each group, and the mean arterial pressure summaries also use 62 participants in each group. The registry does not state whether those groups comprise all randomized participants or a subset defined by outcome availability. Nor does it describe whether the analysis followed assigned groups regardless of adherence, or whether participants were analyzed according to the positioning actually received. These distinctions can matter in randomized trials because they affect the interpretation of the group comparison.

The registry also does not report a protocol, statistical analysis plan, sensitivity analyses, or details on interim analyses. No interim analysis information is reported in the registry record. These absences do not establish that a particular method was or was not used; they mean that the record does not allow those choices to be assessed. The uncertainty is especially relevant when interpreting secondary p-values, since the full set of analyses and the rules governing their interpretation are unavailable.

11. Safety Results

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

Other (non-serious) adverse events

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

For the head-lift group, the registry reports zero serious adverse events among 62 participants at risk and zero other adverse events among 62 participants at risk. For the neutral-position group, it likewise reports zero serious adverse events among 62 participants at risk and zero other adverse events among 62 participants at risk. No serious adverse-event terms are listed.

These figures describe what was recorded in the registry, not proof that no adverse events occurred outside the stated reporting categories or observation period. The registry record does not specify the safety-reporting timeframe, the definitions used for serious and other adverse events, or the method for collecting events. Death counts are not reported in the record; a missing death value should not be interpreted as zero.

General explanation: a zero count in a study does not establish that an event is impossible or that two groups have identical safety profiles. The amount of information depends on the number observed, the observation period, and how events were sought and classified. The posted safety figures are therefore a limited description of recorded events, rather than a comprehensive comparison of risk.

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

The registry results describe a randomized comparison of two head positions during Trachway-assisted orotracheal intubation. The primary summaries show a lower median intubation time for the head-lift group than for the neutral-position group. The registry record does not report an inferential comparison for that endpoint, so the magnitude and precision of the between-group difference cannot be established from the primary summaries alone.

The secondary mean arterial pressure estimate is reported with a confidence interval that includes zero and an unadjusted p-value of 0.088. That result does not demonstrate that the groups are identical, and it does not provide a definitive conclusion about a difference. It is one secondary comparison among several listed outcomes, with no reported multiplicity strategy. Numerical results for the other two listed secondary outcomes are not reported in the registry record.

These findings do not establish whether either positioning method is preferable in clinical practice. The record does not report a threshold for a meaningful reduction in intubation time, a clinical interpretation of the pressure estimates, or enough participant and procedural detail to determine how broadly the findings apply. The results should be understood as observations from the recorded trial conditions, not as a general statement about all adults, all difficult intubations, or other devices and techniques.

The study’s design label indicates randomization, but important implementation details are absent: the randomization method, allocation concealment, identity of the masked party, and analysis population are not reported in the registry record. The relationship between total enrollment and the counts in the outcome summaries is also unexplained. These limitations restrict assessment of possible bias and of how completely the posted results represent the enrolled participants.

General explanation: statistical evidence and clinical importance are distinct. An estimate can be statistically uncertain yet still be compatible with effects that could matter, or it can be precise without being clinically important. Evaluating importance requires a context-specific threshold or rationale, which is not reported in this registry record. Accordingly, the posted figures support descriptive interpretation, but not a definitive conclusion about benefit, harm, or equivalence.

13. Why This Trial Matters Statistically

This trial illustrates how the choice and reporting of an endpoint shape what can be concluded. Intubation time is recorded from stylet contact through capnogram appearance and includes all attempts. That operational definition makes clear what the stopwatch interval represents and highlights why endpoint details matter: a different start point, end point, or approach to repeated attempts could yield a different measure.

The registry reports medians and interquartile ranges for the primary endpoint but does not report an inferential comparison or uncertainty interval. This distinction is statistically important. Descriptive differences can show the pattern in observed data, but they do not communicate how precisely the group contrast has been estimated. Readers should not convert a difference in group summaries into a claim of statistical evidence when the corresponding analysis is not reported.

The trial also demonstrates why secondary outcomes need context. Mean arterial pressure is accompanied by a mean difference, confidence interval, and unadjusted p-value, while numerical results for two other listed secondary outcomes are absent from the record. Without a reported analysis hierarchy or multiplicity approach, the secondary p-value has limited confirmatory meaning. A lone secondary result should not be used to resolve uncertainty in a primary endpoint that lacks a formal comparison.

Finally, randomized design labels do not replace reporting of trial conduct and analysis. Information about allocation, masking, participant flow, analysis populations, and missing data helps readers judge whether results are vulnerable to bias. The unexplained relation between enrollment and outcome counts leaves an important part of that assessment open. The statistical lesson is that an interpretable estimate depends not only on the number reported, but also on the endpoint definition, uncertainty, analysis plan, and accounting of participants.

14. 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.

The registry record leaves several trial-specific questions unanswered. It identifies the study population as adults and lists difficult intubation as a condition, but does not report eligibility criteria, baseline characteristics, or how difficulty was defined. The record does not clarify whether participants were selected for anticipated difficult intubation or whether that label describes the general topic of the trial.

The primary outcome is described as a median with an interquartile range, but there is no reported formal comparison, confidence interval, or p-value. The recorded arm counts are 62 each, while total enrollment is 130; the registry does not explain the participant accounting or reasons for any difference. The analysis population and treatment of missing measurements are not reported in the registry record.

Although the trial is labeled single-masked, the masked party and masking procedures are not reported. The randomization sequence method and allocation concealment are also not described. The intubation-time record specifies an independent observer and stopwatch, but does not state whether that observer was masked to assignment or how timing at the 30-second limit was handled.

The secondary outcomes are incompletely represented in the numerical record. Mean arterial pressure has a reported comparison, but modified Cormack-Lehane grade and visual analog scale of sore throat do not have numerical two-arm summaries reported in the registry record. The record does not give a multiplicity plan, a statistical analysis plan, or a sample-size justification for the trial itself.

Safety information is limited to event counts without a reported observation period or event definitions. Death counts are not reported. Finally, the registry does not provide enough detail about the setting, participant characteristics, or conduct of the procedure to determine how readily the results apply beyond the specific Trachway and chin-lift approach described.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: "Neutral Head Position" and "Head-lift Position" for Orotracheal Intubation With "Trachway" Intubating Stylet in Adults — NCT02578992.
• Registry record last updated 2016-12-09; status last verified 2016-10.
• Results first posted 2016-12-09.
• 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.

18. Record Summary

The registry describes a completed, randomized, single-masked, parallel-group study sponsored by Tri-Service General Hospital (TSGH), comparing head-lift and neutral positions for Trachway-assisted orotracheal intubation in adults. Enrollment is listed as 130. The primary endpoint is intubation time from stylet contact with the mouth until capnogram appearance, including all attempts.

Primary outcome summaries are medians and interquartile ranges, with 62 participants recorded in each arm. The registry does not report a formal primary comparison or explain the relationship between enrollment and the arm counts. Mean arterial pressure is the only secondary outcome with a numerical comparison reported; results for the other listed secondary measures are not reported in the registry record.

Important details about allocation, masking, analysis populations, missing data, multiplicity, and the trial’s sample-size justification are not reported in the registry record. The posted figures support descriptive reading, while the missing analysis and conduct details limit stronger conclusions.