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 The Articulated Oral Airway as an Aid to Mask Ventilation (NCT03144089), a randomized na study. The primary outcome is Expiratory Tidal Volume (Breaths 6-10).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03144089 |
| Phase | NA |
| Condition | Mask Ventilation, Airway Obstruction Upper, Airway Management |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Quadruple |
| Enrollment | 58 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Ron Abrons |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns patients with predictors of difficult mask ventilation, as described in the registry summary. The record does not give further eligibility details or a fuller description of the enrolled population.
Intervention
The Articulated Oral Airway (AOA), a device described as actively displacing the tongue to create more cross-sectional area for mask ventilation. Each participant was intended to receive both oral airways, with the order randomized.
Comparator
The Guedel oral airway (GOA), an active device comparator. The registry describes measurements after placement of each airway, rather than a comparison with no oral airway.
Primary question
Does the AOA produce expiratory tidal volumes that are non-inferior to those with the GOA? Expiratory tidal volume was measured during breaths 6-10 after each device was inserted and expressed in ml/kg. The registry does not report the numerical results or a non-inferiority margin, so it is not possible to determine from the record whether the study met its stated objective.
3. Trial Design
The registry describes a prospective, interventional, randomized, quadruple-masked, crossover study. Its stated status is completed. The study compares the Articulated Oral Airway with the Guedel oral airway during mask ventilation. In a crossover design, participants receive each intervention, so the comparison can be made within the same participant as well as across randomized treatment sequences.
The primary-outcome description says that the order of first treatment was randomized. It reports that 28 participants received the Guedel airway first and 28 received the Articulated Oral Airway first. Measurements were taken during breaths 6-10 after each airway was inserted. The description says that expiratory tidal volumes were weight-standardized, with measurements divided by participant weight in kilograms. It specifies an immediate measurement timeframe averaging 2-5 minutes after placement of each airway.
The registry separately lists enrollment as 58, while the primary-outcome description says that 56 patients were enrolled and randomized. These different counts appear in the record, and the reason for the difference is not reported in the registry record. The arm descriptions indicate that both devices were used by each participant, but the available text is truncated. Further details of the procedure, including any washout or other control of period effects, are not reported in the registry record.
The study is labelled non-inferiority, but the margin that would define an acceptable loss in expiratory tidal volume is not reported in the registry record. The record also does not report the planned statistical method for comparing the paired measurements or the masking procedures. Randomization and masking describe design features; without the outcome estimates and analysis details, they do not establish the result of the comparison.
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 | Guedel Oral Airway Placed First | Articulated Oral Airway Placed First |
|---|---|---|
| STARTED | 28 | 28 |
| COMPLETED | 28 | 28 |
| NOT COMPLETED | 0 | 0 |
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.
| Characteristic | Unit | Guedel Oral Airway Placed First | Articulated Oral Airway Placed First | Total |
|---|---|---|---|---|
| Participants analysed | 28 | 28 | 56 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 19 | 15 | 34 |
| Age, Categorical: >=65 years | Participants | 9 | 13 | 22 |
| Sex: Female, Male: Female | Participants | 12 | 9 | 21 |
| Sex: Female, Male: Male | Participants | 16 | 19 | 35 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States | participants | 28 | 28 | 56 |
| BMI | kg/m^2 | 34.8 (31.0 to 39.0) | 36.1 (33.0 to 40.0) | 35.4 (31.0 to 40.0) |
6. Primary Endpoint
The registry lists the primary outcome as Expiratory Tidal Volume (Breaths 6-10), measured over Measured immediately after placement of each oral airway; an average of 2-5 minutes..
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | ml/kg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean expiratory tidal volume during breaths 6-10 after placement of each oral airway. It is expressed in ml/kg. The registry says the measurements were obtained from video of the anesthesia monitor and divided by participant weight in kilograms. The measurement timeframe is described as immediate after placement, averaging 2-5 minutes.
Expiratory tidal volume is a physiologic measure of the volume of air exhaled during a breath. In this study it serves as a quantitative measure for comparing mask ventilation with the AOA and the GOA. Weight standardization puts measurements on a per-kilogram scale, which can help account for differences in participant body size when describing ventilation volumes.
The endpoint is a mean over the specified breaths, not a direct measure of patient-centered outcomes or longer-term consequences. A difference in this measure, by itself, would not establish a difference in clinical outcomes. The registry identifies a 95% confidence interval as the endpoint’s dispersion measure but gives no numerical means or interval limits. Thus, the precision and direction of the observed comparison cannot be read from the registry record.
For a non-inferiority question, the endpoint estimate must be interpreted relative to a prespecified margin. The margin and numerical comparison are not reported in the registry record, so the endpoint definition alone cannot establish non-inferiority.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies mean expiratory tidal volume during breaths 6-10 as the primary outcome and describes the measure in ml/kg. It does not include the numerical values for the randomized sequences or the comparison between devices. Although the outcome description refers to a 95% confidence interval, the interval limits are not reported in the registry record. The size, direction, and precision of the estimated difference therefore cannot be assessed from the posted results.
This matters especially because the stated objective is non-inferiority. A non-inferiority conclusion is not established merely because a study is designed to compare devices, or because a conventional test does not find a difference. The estimate must be evaluated against a prespecified margin that defines how much lower performance could be while still meeting the study’s criterion. That margin is not reported in the registry record, and the numerical estimate is also absent. The stated non-inferiority question consequently cannot be answered from the available registry information.
The crossover design means measurements from the same participant are relevant to the comparison. General statistical interpretation of such a design considers the within-participant contrast and also whether treatment sequence or period could affect the measurements. The record describes randomized treatment order, but the statistical analysis used and any assessment or handling of period or sequence effects are not reported in the registry record.
The record lists two secondary outcomes: inspiratory tidal volume during breaths 6-10 and immediate oropharyngeal trauma from the airway randomized to be placed first. Numerical results for these outcomes are not reported in the registry record. No outcome-specific estimates or uncertainty measures are available to interpret.
Accordingly, the posted information describes the question and measurement process, but not the outcome evidence needed to characterize the comparison. This is not evidence that the devices had equal results, nor is it evidence that one produced a higher or lower volume. No treatment-effect claim can be drawn from the numerical outcome data because those data are not reported in the registry record.
9. Statistical Methods Explained
The registry identifies the primary outcome as a mean of a continuous measure and gives a 95% confidence interval as its dispersion measure. It does not report the numerical mean values, confidence interval limits, or a statistical analysis for the primary comparison. The following explains the general statistical ideas relevant to the design; it does not describe an analysis confirmed to have been used in this trial.
What a confidence interval conveys
In general, a confidence interval describes the uncertainty around an estimated quantity. For a treatment comparison, it helps readers assess which effects remain compatible with the data under the method used. A narrower interval indicates greater precision than a wider interval, but precision alone does not establish clinical importance. The interval must be considered alongside the endpoint, the direction of the contrast, and—when the objective is non-inferiority—the prespecified margin. The registry record names a 95% confidence interval but does not give its limits, so the precision of the study’s estimated result cannot be evaluated.
How a crossover comparison differs
In general, a crossover design has each participant receive each intervention. The resulting measurements are linked: measurements from one participant may be more alike than measurements from different participants. An analysis can use this pairing to estimate a within-participant contrast, which may reduce the influence of stable differences between participants. Treating all measurements as independent would fail to reflect that linkage.
Pairing does not remove every design concern. Measurements can be influenced by the order in which interventions are received, by changes over time, or by carryover from an earlier intervention. Randomizing sequence can help balance order, but an appropriate analysis still needs to account for the design. The registry reports randomized order and describes both devices being used, but it does not report whether the analysis accounted for pairing, period, sequence, or carryover. It also does not report a washout procedure.
What non-inferiority requires
In general, a non-inferiority study asks whether an intervention is not worse than a comparator by more than a specified, acceptable amount. That amount is the non-inferiority margin. The estimated treatment contrast and its uncertainty are interpreted relative to the margin, with the direction of the contrast defined in the analysis. A conclusion requires the relevant confidence bound to rule out a loss larger than the margin. A non-significant test of difference is not, on its own, proof of non-inferiority.
The registry calls the study non-inferiority and describes the investigators’ hypothesis, but the margin and the planned decision rule are not reported in the registry record. The outcome estimate and confidence limits are also absent. Therefore, the record does not allow readers to apply a non-inferiority criterion or determine whether it was met.
Means and the measurement scale
In general, a mean describes the central value of a continuous outcome, while the observed values may vary among participants. The endpoint uses expiratory tidal volume standardized per kilogram of body weight, with measurements taken during a defined set of breaths after each airway placement. Reporting a mean and an interval can describe both the estimated average and uncertainty in that estimate. It does not show the full distribution of individual measurements, and a mean comparison does not by itself describe every participant’s response.
The registry states that the tidal-volume measure was derived from monitor video and weight-standardized. It does not report details about measurement reliability, assessor procedures, or the analysis of unusual or incomplete measurements. These omissions limit the ability to evaluate how measurement variation and data handling might affect the estimate.
Interpretation of statistical evidence
In general, statistical evidence depends on the estimate, its uncertainty, the analysis assumptions, and the question defined in advance. A p-value, if reported, would address compatibility with a specified null hypothesis under an analysis model; it would not quantify the probability that a hypothesis is true or establish practical importance. No primary-outcome analysis or p-value is reported in the registry record. It would therefore be inappropriate to infer a statistical result from the study design, the enrollment count, or the outcome definition alone.
Details such as the model, treatment contrast, handling of repeated measurements, and assumptions for inference are not reported in the registry record. Without those details and the numerical outcome results, the trial’s statistical conclusion cannot be independently evaluated from the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The record lists a primary outcome and two secondary outcomes. It does not report a multiplicity strategy for interpreting results across outcomes or any planned hierarchy, adjustment, or other procedure for controlling the chance of misleading findings from multiple comparisons. This is relevant when several outcomes are considered, but the absence of a reported strategy does not establish which method, if any, was used.
Missing-data methods are not reported in the registry record. The record does not describe whether any outcome measurements were missing, how incomplete measurements were handled, or whether sensitivity analyses were planned. The discrepancy between the enrollment count of 58 and the primary-outcome description of 56 enrolled and randomized is not explained in the record. It should not be treated as evidence, by itself, that outcome data were missing.
The analysis population is not reported in the registry record. In a randomized crossover study, analysis decisions can concern which participants and periods contribute data and how incomplete pairs are handled. The record does not specify an intention-to-treat, per-protocol, or other analysis population, nor does it explain exclusions or protocol deviations.
Interim analyses, stopping rules, and the statistical analysis plan are not reported in the registry record. The registry lists no analyses, and no numerical primary or secondary outcome results are available in the record. As a result, readers cannot assess the analysis choices, the handling of missing data, or how multiple outcomes were interpreted.
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 |
|---|---|---|---|
| Guedel Oral Airway | 0 | 56 | 0.0% |
| Articulated Oral Airway | 0 | 56 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Guedel Oral Airway | 0 of 56 |
| Articulated Oral Airway | 0 of 56 |
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 |
|---|---|
| Guedel Oral Airway | 0 of 56 |
| Articulated Oral Airway | 0 of 56 |
The registry lists 56 participants at risk in each device group. For the Guedel Oral Airway, it reports 0 serious adverse events, 0 other adverse events, and 0 deaths. For the Articulated Oral Airway, it also reports 0 serious adverse events, 0 other adverse events, and 0 deaths. No serious adverse-event terms are listed.
These figures describe what the registry reports for the recorded groups. They do not establish that adverse events are impossible, or that the devices have identical safety profiles. Zero reported events in a study of this size cannot rule out uncommon events, and interpretation depends on how events were defined, collected, and followed. Those details are not reported in the registry record.
The safety counts should also be read alongside the crossover design: participants were intended to receive both devices, while the registry presents separate device groups for adverse-event reporting. The record does not explain the safety attribution or reporting method. The counts therefore describe the posted safety figures, but do not support a broader comparative safety conclusion.
12. What the Result Does, and Does Not, Mean
The registry record establishes that investigators planned a randomized crossover comparison of the Articulated Oral Airway and the Guedel oral airway, with expiratory tidal volume during breaths 6-10 as the primary measure. The measure was weight-standardized and expressed in ml/kg. The stated objective was non-inferiority in patients described as having predictors of difficult mask ventilation.
What the record does not establish is the result of that comparison. It gives no numerical primary-outcome means, confidence interval limits, or analysis estimate. The non-inferiority margin is also not reported in the registry record. Without the estimate, its uncertainty, and the margin, readers cannot determine whether the AOA was non-inferior, whether the devices differed, or how large or precise any difference was.
The endpoint is a short-term physiologic measurement taken immediately after airway placement. Even if numerical differences were available, this measure would not by itself establish effects on other clinical outcomes. The record does not provide numerical results for the listed secondary outcomes either.
The safety listing reports zero serious adverse events, zero other adverse events, and zero deaths in each of the two device groups, with 56 participants at risk per group. Those counts are limited to the events recorded and cannot exclude uncommon harms or prove equal safety.
Thus, the registry provides useful design and measurement details, but not enough outcome information to support a comparative efficacy or non-inferiority conclusion. This is a limitation of what is reported in the registry record, not evidence that no trial results exist elsewhere.
13. Why This Trial Matters Statistically
This study raises a statistical question that differs from a simple test for whether two averages are unequal. Its stated objective is non-inferiority: the relevant question is whether the AOA’s expiratory tidal volume is not unacceptably worse than the GOA’s under a defined margin. That distinction matters because a failure to detect a difference does not, by itself, show that treatments are sufficiently similar.
The crossover design also makes the structure of the data important. Each participant was intended to receive both devices, and the randomized order helps define how within-participant measurements are compared. Appropriate interpretation depends on accounting for the relationship between measurements from the same person, as well as considering order and period effects. The registry describes the sequence allocation but does not report the analysis used to address these features.
The outcome is a standardized physiologic measure collected over a short period after device placement. It offers a defined way to compare ventilation measurements, but statistical evidence on this endpoint would not automatically answer broader questions about patient outcomes. This is a useful distinction between what a trial measures and what its results might support.
Finally, this record illustrates why a complete registry result matters. Design labels and a stated hypothesis do not reveal the estimated treatment effect or its precision. With no numerical endpoint results or non-inferiority margin reported in the registry record, readers cannot evaluate the central statistical claim. The available safety counts provide descriptive information, but they do not fill that gap.
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 principal limitation for interpreting the comparison is that numerical primary-outcome results are not reported in the registry record. The record names the endpoint and its confidence-interval format but gives no means, interval limits, or treatment contrast. The stated non-inferiority margin is also absent, preventing assessment against the study’s stated objective.
The enrollment information is not internally reconciled in the record: the listed enrollment is 58, while the primary-outcome description says 56 patients were enrolled and randomized. The reason for these different counts is not reported. The available arm descriptions are truncated, so they do not fully document the procedures for each sequence.
Important methods details are not reported in the registry record, including the statistical model, treatment of paired measurements, handling of period or sequence effects, missing-data methods, analysis populations, and multiplicity approach. The registry also does not report measurement reliability procedures or further eligibility details. These omissions make it difficult to judge the robustness of an analysis, even if the numerical outcome results were available.
The posted safety figures report no events in the listed categories, but event definitions, collection procedures, and follow-up details are not reported. The results are therefore limited to the registry’s event counts and should not be interpreted as ruling out uncommon harms. These constraints concern what can be evaluated from the registry record; they do not establish how the full study was conducted beyond the details recorded.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Articulated Oral Airway as an Aid to Mask Ventilation — NCT03144089.
- Registry record last updated 2021-07-23; status last verified 2021-07.
- Results first posted 2021-07-23.
- 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
NCT03144089, titled “The Articulated Oral Airway as an Aid to Mask Ventilation,” is listed as a completed, prospective interventional non-inferiority study. The registry describes randomized allocation, quadruple masking, and a crossover model. The study compares the Articulated Oral Airway with the Guedel oral airway in patients described as having predictors of difficult mask ventilation.
The primary outcome is mean expiratory tidal volume during breaths 6-10 after device placement, measured immediately and expressed in ml/kg, with a 95% confidence interval identified as the dispersion measure. The primary-outcome description says 56 patients were randomized, while the overall enrollment listing is 58. Numerical primary and secondary outcome results, the non-inferiority margin, and the statistical analysis are not reported in the registry record.
The safety record lists 56 at risk in each device group and zero serious adverse events, zero other adverse events, and zero deaths for each. The registry lists a start date of 2017-07-11 and a primary completion date of 2019-02-25.