Ventilation Using a Bag Valve Mask With Supplemental External Handle: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ventilation Using a Bag Valve Mask With Supplemental External Handle (NCT02800213), a randomized na study. The primary outcome is Received Tidal Volume.

2. Clinical Question

3. Trial Design

This was a randomized, single-masked, crossover trial using a manikin model. The official title describes a comparison of single-rescuer ventilation with a modified bag valve mask versus a standard bag valve mask. The record lists the trial status as completed and the sponsor as Brooke Army Medical Center. The recorded start and primary-completion month are both 2016-05.

The described procedures had health volunteers use both devices. One sequence began with the modified mask and then used the conventional mask; the other began with the conventional mask and then used the modified mask. Randomization therefore concerned the order of device use as described in the arm entries. The record does not report details of sequence generation, allocation concealment, a washout period, or how the single masking was implemented. It also does not identify who was masked.

For each device, the volunteer was described as delivering 10 breaths per minute for 3 minutes to an IngMar RespiTrainer manikin. The arm descriptions then say the procedures were repeated with the other device. The primary measure is described as the mean received tidal volume for 30 breaths over three minutes, measured through the RespiTrainer Advance manikin monitor output. This setup examines performance under a specified simulated task, not ventilation in patients.

The registry reports 70 in each arm entry and 70 enrolled. In a crossover design, arm entries can represent device conditions or sequences rather than independent groups. The record does not explain the relation between the enrollment figure and the arm-level counts beyond listing those values; no total of distinct participants should be inferred from the arm entries.

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.

First Intervention

Second Intervention

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 Received Tidal Volume, measured over 3 minutes.

The primary endpoint was received tidal volume, measured in milliliters. Tidal volume is the volume of air delivered with a breath. The registry defines the reported value as the mean received volume for 30 breaths delivered over three minutes and measured by the RespiTrainer Advance manikin monitor output.

This measure was used to compare the amount of ventilation received by the manikin under the two device conditions in the specified single-rescuer exercise. A mean provides a concise description of the average measured volume across the breaths included in the endpoint. It can be useful for comparing device performance in a controlled simulation, where the task and measurement apparatus are specified.

The endpoint is a manikin measurement, not a clinical outcome. The registry does not report patient-level ventilation, oxygenation, survival, or other outcomes of care. Nor does it report a separate measure of whether breaths were delivered consistently, the number of technically adequate breaths, or the performance of users in a clinical setting. Those should not be inferred from the mean received volume.

The posted arm-level means are accompanied by 95% confidence intervals. These intervals describe uncertainty around the reported mean estimates under the analysis used; they are not a confidence interval for the difference between devices. The registry does not provide a direct confidence interval for that contrast.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the reported mean describe?

A mean is the arithmetic average of the observations included in an analysis. For this trial, the endpoint description says the mean was based on received tidal volume for 30 breaths delivered over three minutes. It is an arm-level summary of a continuous measurement. A mean is informative about the center of the observed values, but by itself does not show how much individual breath measurements varied. The registry does not post a standard deviation or another measure of within-arm spread for this endpoint.

The record reports a mean and a 95% confidence interval for each device. A confidence interval gives a range of values compatible with the data and the stated statistical procedure, reflecting sampling uncertainty. It is not a range containing 95% of individual breath volumes, and it is not a guarantee that the true value lies in that particular interval. The reported intervals concern each arm's mean. They do not directly answer how precisely the difference between the device means has been estimated.

What does the t-test address?

The registry reports a two-sided t-test. In general, a t-test assesses whether observed data are compatible with a null hypothesis about a mean or mean difference, using an estimate and its standard error. A two-sided test considers departures in either direction rather than only a prespecified increase or decrease. The reported p-value is 0.280. It is a measure of how unusual the test statistic would be under the null hypothesis and the assumptions of the test; it is not the probability that the null hypothesis is true.

The registry does not state whether the t-test was paired. This detail matters in a crossover trial. A paired analysis uses the within-volunteer relationship between measurements under the two devices; an independent-groups analysis treats them as unrelated. When the same people use both devices, accounting for that pairing can affect the estimated standard error. The registry also does not specify the exact analysis population, handling of missing measurements, or treatment of sequence and period effects.

Why is the crossover structure relevant?

In general, crossover designs compare conditions within the same participant and can reduce variation due to stable differences between participants. That advantage depends on a suitable analysis of the paired observations and on the design being implemented as intended. Order can also matter: practice, fatigue, carryover, or other period-related influences may affect later measurements. These are general considerations, not reported findings about this trial. The registry describes two device orders but does not report an analysis of order, period, or carryover effects.

For measurements involving multiple breaths from a volunteer, observations may also be correlated within that volunteer. General statistical methods can account for this clustering rather than treating every breath as independent. The endpoint is described as a mean across 30 breaths, but the record does not clarify whether the analysis used each volunteer's mean, individual breath measurements, or another data structure. It does not report whether the method allowed for over-dispersion or correlation among repeated observations. Over-dispersion, in general, means that variability is greater than a model assumes; accounting for it can matter when standard errors are estimated. The registry does not identify this as an issue in the trial.

How should the p-value and confidence intervals be read together?

The p-value summarizes evidence against a specified null hypothesis under a particular test. It does not give the magnitude of an effect or indicate its practical importance. The confidence intervals for the separate arm means show uncertainty in those means, but they are not a substitute for a confidence interval for the between-device contrast. Even when two arm intervals overlap, the overlap alone is not a formal test of the contrast. A direct contrast estimate with its standard error or confidence interval would show both direction and precision more clearly.

The registry does not report a between-device estimate, confidence interval, or a prespecified margin for interpreting the size of a difference. It also does not report a statistical analysis plan. Consequently, the posted test can be described, but important details needed to reproduce or fully assess that test are not reported in the registry record.

What can planning calculations establish?

Sample-size illustrations based on an observed effect are planning scenarios, not evidence about the trial's actual design or its ability to detect an effect. In general, such calculations depend on assumptions about the target effect, variability, significance level, allocation, and analysis. The record describes a planning approach using a two-sided significance level of 0.05, equal allocation, a normal approximation, and fractions of an observed effect. It does not report that these assumptions were used to design this trial, nor does it report the trial's own sample-size justification. A planning calculation must not be interpreted as observed power or as proof that the analysis could reliably detect a clinically important difference.

10. Analyses Reported by the Sponsor

The registry's reported analysis is a two-sided t-test with p = 0.280. It does not include a test statistic, an estimated between-device difference, or a confidence interval for that difference. The record also does not specify whether the t-test accounted for the crossover pairing.

No recalculated between-arm test or contrast is reported for these continuous results: the registry record lacks the information needed to estimate that comparison from posted summary statistics. The separate arm means and confidence intervals do not by themselves determine the uncertainty of a paired contrast. The record marks no discrepancy, so there is no conflict between a sponsor analysis and a recalculation to resolve. In any event, the sponsor's own analysis takes precedence when a discrepancy is identified.

The reported p-value should therefore be read as the registry's stated test result, with the analysis details and contrast estimate left unspecified. The arm-level estimates are descriptive context, not an independently reconstructed test of the crossover comparison.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and one reported analysis, and it reports no secondary outcomes. The multiplicity of endpoints or statistical tests beyond those listed is not reported in the registry record. It does not state whether additional analyses were conducted, whether the primary comparison was selected before examining the results, or whether any adjustment for multiple testing was planned. With no multiplicity plan reported, the stated p-value should be understood as the result of the listed test, not as evidence that all possible analyses were considered or controlled.

The analysis population is not described. The record reports enrollment and arm-level counts, but it does not state whether all enrolled volunteers were included in the primary analysis, whether the analysis followed assigned sequence, or how deviations from the intended procedures were handled. Missing outcome data, exclusions, and reasons for any missing observations are not reported in the registry record.

The crossover description raises additional analysis questions. The record does not state how the order of device use was generated or whether the analysis accounted for paired measurements, sequence, period, or carryover. It does not report whether the same number of usable measurements was available for each device or how incomplete measurement sequences would be handled.

These omissions do not establish that the analysis was inappropriate; they limit what can be assessed from the registry. A fuller statistical account would ordinarily clarify the prespecified primary analysis, analysis population, missing-data approach, treatment of crossover structure, and any planned multiplicity control. Those details are not reported in the registry record.

12. 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.

The adverse-event entries report zero serious adverse events and zero other adverse events for each device condition, with 70 at risk listed for each. The record does not provide serious adverse-event terms. Deaths are not reported in the registry record.

These entries describe what was recorded for this manikin-based exercise. They should not be interpreted as a clinical safety comparison: the task involved health volunteers ventilating a manikin, not patients receiving treatment. The adverse-event definitions, collection procedures, and observation period are not reported in the registry record. The crossover design also means the arm entries should not be treated as independent participant groups or added to derive a count of distinct people.

Zero events recorded does not establish that an event is impossible or that the devices have equivalent safety. It means that the registry lists no events in the stated categories for the conditions and at-risk counts recorded. The size and scope of this simulated study do not support broader safety conclusions.

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

The posted results describe mean received tidal volume during a defined manikin exercise. The modified mask arm has a reported mean of 662.0 milliliters, and the conventional mask arm has a reported mean of 681.0 milliliters. Their respective 95% confidence intervals are 611.0 to 707.0 milliliters and 635.0 to 731.0 milliliters. The registry's two-sided t-test reports p = 0.280. These figures are evidence about the registered task and measurements, not outcomes of patient care.

The result does not prove that the two masks produce identical received volumes. Nor does the reported p-value establish that a difference is clinically important or unimportant. A direct estimate and confidence interval for the device contrast would be needed to describe its direction and precision clearly. Neither is reported in the registry record. The test's handling of the crossover structure is also not reported, which limits interpretation of the comparative uncertainty.

The trial does not show whether either device changes patient outcomes. It does not report clinical ventilation, oxygenation, complications, or survival outcomes. A manikin measurement under a specified rate and duration cannot establish how a device performs across patients, rescuers, settings, or ventilation conditions that were not studied.

The record also does not report a sample-size justification, a clinically meaningful difference, or detailed methods for missing data and analysis populations. Those omissions do not negate the reported measurements, but they restrict conclusions about precision, relevance, and reproducibility. The most defensible reading is narrow: the registry records similar-looking arm-level mean measurements in this simulation and a two-sided test that did not indicate strong evidence against its null hypothesis. It does not establish equivalence or support a treatment recommendation.

14. Why This Trial Matters Statistically

This trial is statistically instructive because it combines a continuous endpoint with a crossover design. A reader may be tempted to compare two arm means as though they came from independent groups. In a crossover, the same volunteer uses both conditions, so the paired relationship between measurements can matter to the uncertainty of the comparison. The registry reports a t-test but does not identify whether it was paired, making the analysis structure a key interpretive question.

It also illustrates why separate confidence intervals for each condition are not enough to characterize a comparison. The intervals describe uncertainty around each mean, while a direct contrast estimate and its interval would show uncertainty around the difference. The registry reports no such contrast. The p-value gives a test result, but not the effect's precision or practical importance.

The simulated setting is another important statistical boundary. Standardized manikin measurements can address a focused performance question, but the target of inference remains the registered task. Results from this setting should not be extended automatically to clinical outcomes or to different users and conditions.

Finally, the record shows the value of reporting analysis details alongside summary statistics. Information about pairing, period effects, missing observations, and the analysis population would help readers judge how the test corresponds to the randomized crossover design. Their absence does not alter the posted numbers, but it narrows the claims those numbers can support.

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.

The primary limitation is that the endpoint came from a manikin exercise. The trial description concerns health volunteers ventilating an IngMar RespiTrainer manikin, so the posted result is not a direct measure of patient care or clinical outcome. The record does not report whether findings generalize beyond the specified task, device setup, or user group.

The comparative analysis is difficult to fully assess because the registry reports only a two-sided t-test and a p-value. It does not report the between-device mean difference or its confidence interval, and it does not state whether the test was paired to reflect the crossover design. Details on sequence generation, allocation concealment, masking implementation, period effects, and carryover are not reported in the registry record.

The record reports arm-level means and confidence intervals but no standard deviation or other measure of breath-level variability. It does not clarify how the 30 breaths were represented in the analysis, whether volunteer-level averages were used, or how within-volunteer correlation was handled. The analysis population and missing-data methods are also not reported.

The registered description uses differing language for the modified device: the brief summary refers to a supplemental external handle, while an arm description refers to an integrated internal handle. The registry record does not resolve that wording difference. It also does not report a sample-size justification or a threshold for a meaningful difference. These limits constrain interpretation of the device comparison, its precision, and its relevance outside this simulation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Ventilation Using a Bag Valve Mask With Supplemental External Handle — NCT02800213.
• Registry record last updated 2017-10-09; status last verified 2017-10.
• Results first posted 2017-10-09.
• 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.

19. Record Summary

NCT02800213 is a completed randomized, single-masked crossover trial sponsored by Brooke Army Medical Center. The record lists 70 enrolled and describes health volunteers using a modified and a conventional Ambu Spur II bag valve mask in two possible orders while ventilating a manikin.

The primary endpoint was mean received tidal volume, measured in milliliters over three minutes. The posted means were 662.0 for the modified mask and 681.0 for the conventional mask, with separate 95% confidence intervals. The registry reports a two-sided t-test with p = 0.280, but no direct contrast estimate or confidence interval. The reported results concern a manikin model; analysis details for the crossover comparison are not reported in the registry record.