This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Comparison of Airway Intubation Devices When Using a Biohazard Suit (NCT01924559), a randomized na study. The primary outcome is Time to Successful Intubation.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01924559 |
| Phase | NA |
| Condition | Intubation; Difficult |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | None (open label) |
| Enrollment | 37 |
| Arms in the primary outcome | 6 |
| Lead sponsor | Lehigh Valley Hospital |
| Results posted | Yes |
2. Clinical Question
Population
Emergency medicine residents who tested or participated in each of the six study groups. Intubation was performed on manikins, so the endpoint concerns simulated procedures rather than intubations in patients.
Intervention
The study conditions combined direct laryngoscopy, Glidescope, or the supraglottic airway device identified as SALT with either standard clothing or biohazard gear. The registry describes the study as examining intubation-device performance when using a biohazard suit.
Comparator
There was not a single two-arm comparator. The six conditions allow descriptive consideration of each device under standard clothing and under biohazard gear. Direct laryngoscopy with standard clothing is designated as the control condition in the registry, but the posted results do not report formal comparisons against it.
Primary question
How long did it take to achieve successful intubation in each device-and-clothing condition? Success was defined by two breaths demonstrating lung expansion. The study was intended to investigate the effect of biohazard gear on time and to compare the supraglottic airway approach with direct laryngoscopy and video intubation techniques.
The clinical question is a procedural feasibility question, not a test of patient outcomes. The residents worked on manikins, and the recorded endpoint was time from the start of an attempt to the specified sign of successful ventilation. Consequently, the results describe simulated task performance in the study conditions. They do not directly describe success, safety, or timing in patient care.
The crossover structure means that the study conditions were arranged for participants to take part across conditions. The registry does not report the order in which conditions were attempted or whether the order was randomized. It also does not describe a washout or practice procedure. Those details matter when considering whether differences in timing could reflect device and clothing conditions, learning during repeated attempts, or the order of the tasks.
3. Trial Design
The registry describes NCT01924559 as a randomized, unmasked, crossover feasibility study. It was sponsored by Lehigh Valley Hospital, began in 2013-08, had primary completion in 2013-09, and is listed as completed. The recorded enrollment is 37. The record describes emergency medicine residents performing simulated intubations on manikins.
The six conditions combine three device approaches with two clothing conditions: direct laryngoscopy, Glidescope, and supraglottic airway, each with standard clothing or biohazard gear. The arm descriptions specify manikin intubations. The record labels the supraglottic-airway arms as SALT in the outcome results. The brief study description refers to a Supraglottic Airway Laryngopharyngeal Tube and to direct laryngoscopy and fiber-optic video techniques; the recorded arms identify Glidescope as the video device.
Randomization is reported, but the registry does not explain what was randomized, such as the order of conditions, nor does it describe allocation procedures. Masking is listed as none. In a task involving visible devices and clothing, the conditions would be apparent to the person performing the task, but the record does not discuss masking of anyone who recorded or assessed times.
The crossover format can make comparisons within the same resident possible, because residents participate in multiple conditions. In general, such comparisons may account for stable differences in speed between participants. They also require attention to sequence, practice, fatigue, and carryover between tasks. The record does not report the condition sequence, intervals between attempts, or methods used to address those effects. It does not describe a protocol deviation process or explain how incomplete attempts would be handled.
The study is marked as phase not applicable, consistent with its device-and-simulation focus. The registry records one primary outcome measure and no posted secondary outcome measures. It does not report a sample-size justification or a detailed statistical analysis plan. Although the record gives planning assumptions for an illustrative calculation, it does not give numerical planning estimates in the registry record for interpretation.
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
| Stage | All Study Participants |
|---|---|
| STARTED | 37 |
| COMPLETED | 37 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: EM Residents who tested/participated in each of the six groups
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: Prospectively enrolled EM residents, including PGY 1s through 4s; each resident was observed performing all six arms of the study.
| Characteristic | Unit | SALT and Biohazard Gear |
|---|---|---|
| Participants analysed | 37 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 37 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 10 |
| Sex: Female, Male: Male | Participants | 27 |
6. Primary Endpoint
The registry lists the primary outcome as Time to Successful Intubation, measured over approximately one minute.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | seconds |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is time to successful intubation, measured in seconds. It is defined as the time from initiation of an intubation attempt until two breaths demonstrate lung expansion. The population description is emergency medicine residents who tested or participated in each of the six groups. The registry gives an approximate timeframe of one minute and describes the endpoint as estimated less than 1 minute.
Timing is a direct measure of how quickly a simulated attempt reaches the study’s stated success criterion. It is relevant to a feasibility study because it can describe the time burden of performing the task with different devices and clothing conditions. A time endpoint can also distinguish between procedures that reach the same defined endpoint but take different lengths of time. By itself, however, it does not describe how often attempts fail, whether the technique would be successful in patients, or whether any difference would matter clinically.
The registry reports the outcome parameter as a mean and identifies the dispersion as a full range. A mean summarizes the average recorded time within a condition; the range gives the lowest and highest recorded times. The full ranges are broad in the posted results, so the mean alone does not convey how variable individual times were. The record does not provide a standard deviation, median, confidence interval, or distributional summary beyond the range.
The endpoint’s operational definition is important for interpretation: success is tied to the specified two breaths and lung expansion, not to a broader clinical assessment. The registry does not report independent adjudication of success, a measurement instrument, or further detail on timing procedures. Those measurement details are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted results describe mean times and full ranges for each of the six device-and-clothing conditions. For direct laryngoscopy, the mean was 54.0 seconds with standard clothing and 106.5 seconds with biohazard gear; the respective ranges were 25.0 to 189.0 seconds and 29.0 to 534.0 seconds. For Glidescope, the mean was 66.0 seconds with standard clothing and 83.5 seconds with biohazard gear; the respective ranges were 19.0 to 298.0 seconds and 25.0 to 375.0 seconds. For SALT, the mean was 73.5 seconds with standard clothing and 58.5 seconds with biohazard gear; the respective ranges were 13.0 to 328.0 seconds and 20.0 to 168.0 seconds.
These are descriptive summaries, not estimates from a reported inferential analysis. The registry lists no outcome analyses, and it does not give confidence intervals, p-values, or model-based comparisons. It is therefore not possible to tell from the posted results how precisely any difference between conditions was estimated or whether an analysis accounting for the crossover design found evidence of a difference. No pairwise effect estimates are reported.
The reported means should be read alongside the full ranges. The ranges show that observed times varied substantially within conditions, including times well beyond the timeframe described in the outcome record. A mean can be affected by unusually long observations; when the distribution is skewed, it may not represent a typical attempt well. The record does not provide enough distributional information to determine the shape of the times or how influential the longest observations were.
The six condition summaries do not on their own separate the effect of clothing from the effect of device. A comparison of biohazard gear with standard clothing would need to be considered within device, while a comparison of devices would need to account for clothing and the crossover structure. The registry gives no such adjusted or paired analysis. Descriptive differences between the displayed means should not be treated as causal estimates.
Because the task was performed on manikins by residents, the results concern simulated intubation performance in this study setting. They do not establish what would happen in patient care, with other operators, or under different training and procedural conditions. The feasibility label and lack of formal outcome analysis further limit conclusions: the record shows the measurements collected, but does not report statistical evidence supporting a definitive ranking or a conclusion about device performance.
9. Statistical Methods Explained
What does the mean summarize?
For each condition, the registry reports a mean time. A mean is calculated by combining observed values and dividing by the number of observations. It summarizes the overall level of the measurements but does not show how those measurements are distributed. In particular, a small number of long times can pull a mean upward. The reported full range adds information about the extremes, but it does not show how many observations were near either end or how densely observations were clustered around the mean.
For these results, the mean and range answer different descriptive questions. The mean gives a central summary of times, while the range gives the lowest and highest times recorded in that condition. Neither is a measure of precision for a comparison. A confidence interval would convey uncertainty around an estimated quantity under a stated statistical method; no confidence intervals are reported in the registry record. Without them, readers cannot assess the precision of a condition mean or of a difference between conditions.
Why does the crossover structure matter?
In a crossover study, participants experience multiple conditions, so observations from the same participant are related. A general advantage of a within-participant comparison is that each person can act as a reference for their own performance. That can reduce the influence of stable differences in speed between people. The statistical analysis must preserve that pairing rather than treating all observations as unrelated.
The structure also creates potential order effects. Participants may become faster through practice, or slower through fatigue, as tasks proceed. An earlier condition might influence performance in a later condition. General crossover methods address these issues through design and analysis, for example by recording sequence and using methods that account for paired observations. The registry does not report the order of conditions, sequence allocation, or an analysis method that accounts for within-resident dependence. Thus the degree to which the posted condition summaries reflect paired comparisons is not reported.
Why can a range and mean be insufficient?
Time measurements can be asymmetric: many attempts may be relatively quick while a few take much longer. In general, this kind of right-skew can make the mean sensitive to extreme values. The full range draws attention to the extremes, but does not show the distribution’s shape. A median, quantiles, or a plot of individual observations could describe that shape from other perspectives, but those numerical summaries are not reported in the registry record. No additional distributional assumptions should be imposed on the posted data.
For comparing conditions, an effect estimate would state the size and direction of a defined contrast, and an interval would show the uncertainty around that estimate. The record instead lists group means and ranges without an inferential comparison. It does not report a paired mean difference, a model coefficient, a confidence interval, or a test statistic. Recalculating a comparison from the summaries alone would not recover the crossover analysis, because the within-person pairing is unavailable in those summaries.
What does over-dispersion mean in general?
Over-dispersion is a general issue in statistical models for count data: observed variation is greater than the model’s assumptions allow. When it is ignored, uncertainty can be understated and inferential results can be misleading. The primary endpoint in this study is elapsed time, not a count outcome, and the registry does not report a model assessing over-dispersion. This concept therefore does not supply a method or result for interpreting these times. More broadly, statistical methods must match both the outcome type and the study design; a count-data concept should not be applied to a continuous time endpoint without justification.
What analysis plan is reported?
The registry lists one primary outcome measure, but no analyses are posted. It does not report a statistical model, a contrast hierarchy, treatment of repeated measures, covariate adjustment, handling of missing measurements, or a method for checking assumptions. The record also does not report whether any interim analyses were planned or conducted. These details are not reported in the registry record, so no particular analysis should be inferred from the study’s randomized or crossover labels.
The record gives assumptions for an illustrative sample-size calculation: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Those are planning assumptions, not evidence that the study had a particular power or that a result was observed with a given precision. The record does not report numerical outputs for those illustrations here, and the study’s own sample-size justification is not reported in the registry record. A planning calculation should not be called observed power.
In general, sample-size planning depends on the outcome variability, target effect, design, and chosen error rates. A calculation for an independent two-arm comparison may not represent a crossover design unless its assumptions account for paired measurements and within-person variability. The registry’s stated illustrative assumptions do not establish that the study used that design calculation for enrollment. Since the record does not describe the study’s design justification or analysis plan, the planning information cannot resolve uncertainty about the precision of these results.
10. Multiplicity, Missing Data and Analysis Populations
The study has six device-and-clothing conditions and one primary outcome measure. Several possible comparisons could be posed: clothing conditions within each device, devices within each clothing condition, or broader contrasts across conditions. The registry does not specify a primary contrast or a hierarchy of comparisons. It also does not report an adjustment for multiple comparisons or explain whether any comparisons were prespecified. Consequently, the posted results do not establish which contrast, if any, should be treated as the main inferential question.
Multiplicity is a general concern when many hypotheses are tested. As the number of tests grows, the chance of at least one apparently unusual result can rise if each test is interpreted separately. Statistical approaches can address this by defining a primary comparison in advance or adjusting inference across a family of tests. Those are general principles; the registry record does not report which approach was used, and no inferential tests are posted.
The record does not give a flow of residents or attempts through the conditions, nor does it state whether all measurements were available for every participant. It reports an enrollment of 37 and records 37 observations for each condition, but does not describe missing-data rules, exclusions, or whether the outcome summaries include every attempted procedure. Missing-data handling is not reported in the registry record.
The analysis population is also not defined beyond the description of emergency medicine residents who tested or participated in the groups. The registry does not say whether results were analyzed according to randomized order, according to completed conditions, or under another population definition. Those details matter in a crossover study because incomplete participation could affect the set of paired observations. No imputation or sensitivity analysis for missing outcomes is reported. These omissions prevent assessment of how incomplete data, if any, affected the summaries.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| DL & Standard Clothing | 0 | 37 | 0.0% |
| DL & Biohazard Gear | 0 | 37 | 0.0% |
| Glidescope & Standard Clothing | 0 | 37 | 0.0% |
| Glidescope & Biohazard Gear | 0 | 37 | 0.0% |
| SALT & Standard Clothing | 0 | 37 | 0.0% |
| SALT and Biohazard Gear | 0 | 37 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| DL & Standard Clothing | 0 of 37 |
| DL & Biohazard Gear | 0 of 37 |
| Glidescope & Standard Clothing | 0 of 37 |
| Glidescope & Biohazard Gear | 0 of 37 |
| SALT & Standard Clothing | 0 of 37 |
| SALT and Biohazard Gear | 0 of 37 |
The registry lists zero serious adverse events affected and zero other adverse events affected in each of the six conditions. These are the posted event counts, not evidence that adverse events could not occur. The record does not provide event descriptions because no terms are listed among the serious events. Death counts are not reported in the registry record.
Safety figures need to be interpreted in the context of the study activity. The arm descriptions specify simulated intubations on manikins by residents. The posted event figures therefore belong to this study record and its reported conditions; they should not be read as an estimate of adverse-event risk during patient intubation. The registry does not give further detail about how adverse events were defined, collected, or assessed.
A zero count can reflect no events recorded under the study’s reporting process, but it does not by itself establish that the underlying risk is zero. Assessing safety generally requires information about the population, exposure, event definitions, duration of observation, and completeness of reporting. The record does not give additional details on monitoring or follow-up for adverse events. The counts should therefore be described as reported, without extending them to a broader clinical setting.
12. What the Result Does, and Does Not, Mean
The results show descriptive variation in mean time across simulated intubation conditions. The recorded means are 54.0 seconds for direct laryngoscopy with standard clothing, 106.5 seconds for direct laryngoscopy with biohazard gear, 66.0 seconds for Glidescope with standard clothing, 83.5 seconds for Glidescope with biohazard gear, 73.5 seconds for SALT with standard clothing, and 58.5 seconds for SALT with biohazard gear. The corresponding full ranges are also broad, indicating that individual recorded times varied within each condition.
These summaries do not show whether any observed difference is statistically distinguishable from variation between attempts or participants. No confidence intervals, formal tests, or paired comparisons are reported. The means should not be interpreted as an estimate of the causal effect of clothing or device, because the registry does not report an analysis that accounts for the crossover design, condition order, or other potential influences.
The study addresses performance on manikins by emergency medicine residents. It does not measure patient outcomes, and it does not establish whether the same timing patterns would occur in clinical practice. The endpoint is limited to elapsed time until the specified two breaths demonstrate lung expansion. The record does not report additional measures of procedural success or clinical consequences.
The completed feasibility study can be read as a set of condition-specific measurements that may inform questions for further study. It cannot, from the posted results alone, establish a definitive ranking of devices, a reliable estimate of the effect of biohazard gear, or a conclusion about effectiveness or safety in patients. The registry record does not report a formal analysis that would support those claims. Its contribution is descriptive: it records simulated times and ranges under the tested conditions.
13. Why This Trial Matters Statistically
This study is statistically interesting because its design and outcome raise issues that are easy to miss when only condition averages are considered. The crossover structure implies repeated measurements within residents, which makes the relationship between observations important. An analysis that ignores that dependence could answer a different question from an analysis that compares conditions within the same resident. Yet the registry reports condition-level means and ranges without a paired analysis or details on sequence.
The six conditions also create more than one possible comparison. The effect of clothing could vary by device, and the apparent contrast between devices could depend on clothing. A single overall statement about device or protective clothing would therefore require a clearly defined comparison and a method suited to the design. The registry does not identify such a primary contrast or report inferential analyses, leaving the posted summaries descriptive rather than decisive.
The broad ranges matter as well. A mean may not fully characterize a time distribution with long observations, and a full range does not show the frequency or clustering of those observations. Reporting individual-level distributions and paired contrasts could help readers understand both variability and the precision of differences. Those analyses are not reported in the registry record.
Finally, the simulated setting limits the target of inference. Statistical precision within a manikin exercise would not by itself establish applicability to patient care. The study’s value is in making the measurement question concrete: the task can be timed under different device and clothing conditions. Its limits show why sound interpretation requires the design, analysis, and context to be considered together, rather than treating condition means as stand-alone evidence.
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 reports limited methodological detail beyond randomization, no masking, and a crossover model. It does not explain the randomization procedure or what aspect of the study was randomized. Condition order, interval between attempts, practice effects, fatigue, and any carryover are not described. These omissions make it difficult to assess whether the observed times could reflect sequence as well as the assigned device and clothing conditions.
The task was performed on manikins by emergency medicine residents. This supports interpretation as a simulation study but limits generalization to patient intubation, other clinical operators, or other settings. The registry does not report participant experience, training, or other characteristics that could help readers judge how representative the residents were of a broader group.
The outcome is operationally defined by timing until two breaths demonstrate lung expansion, but the record does not describe the timing equipment, observer procedures, or adjudication of success. The endpoint is reported as a mean with a full range, without standard deviations, medians, confidence intervals, or individual-level data. Its ranges include long times relative to the approximate one-minute timeframe stated in the record.
No formal analyses are posted, and the record does not report paired comparisons, adjustment for multiple comparisons, missing-data methods, or an analysis population. It also does not explain whether all attempts were completed or how unsuccessful attempts were handled. A study-specific sample-size rationale and statistical plan are not reported in the registry record. These limitations mean the descriptive results cannot establish the precision, statistical significance, or causal interpretation of differences between conditions.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Comparison of Airway Intubation Devices When Using a Biohazard Suit — NCT01924559.
- Registry record last updated 2017-05-09; status last verified 2017-03.
- Results first posted 2016-03-25.
- 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.
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18. Record Summary
NCT01924559 is a completed randomized, unmasked crossover feasibility study sponsored by Lehigh Valley Hospital. The registry lists an enrollment of 37, a start date of 2013-08, and primary completion in 2013-09. Emergency medicine residents performed simulated intubations on manikins using direct laryngoscopy, Glidescope, or SALT with standard clothing or biohazard gear.
The primary outcome was time to successful intubation, defined by two breaths demonstrating lung expansion. The registry reports condition-specific means and full ranges. It lists no posted outcome analyses and no secondary outcome measures. The record does not report formal comparisons, confidence intervals, or a detailed statistical analysis plan.
Results are descriptive measurements from a simulated setting. The record does not establish how differences between conditions should be interpreted statistically or whether they apply to patient care.