Contract-Relax (CR) Technique in the Management of Diaphragmatic Paresis After Cardiac Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Contract-Relax (CR) Technique in the Management of Diaphragmatic Paresis After Cardiac Surgery (NCT05068219), a randomized na study. The primary outcome is Diaphragmatic Excursion in Maximum Inspiration.

2. Clinical Question

This is a focused question about an early change in a physiological measurement after surgery, rather than a direct comparison of longer-term recovery or a broad clinical outcome. The registry also lists secondary outcomes covering normal-inspiration excursion, oxygen measures, respiratory support, respiratory complications, length of stay, and pain. Their inclusion indicates the range of outcomes tracked, but does not establish that results for them were reported. The record identifies the trial as completed, with enrollment of 27, but does not provide an analysis population or endpoint values.

3. Trial Design

The registry identifies NCT05068219 as a completed, randomized, double-masked, parallel-group trial of the Contract-Relax technique in physical therapy management of diaphragmatic paresis after cardiac surgery. Enrollment is recorded as 27. The two intervention groups were usual physical therapy, described as standard rehabilitation, and the CR technique, described as standard rehabilitation plus 3 CR. The record does not describe the randomization sequence, allocation concealment, or how masking was implemented.

The trial started on 2021-11-25, and primary completion is recorded as 2023-10-21. The phase is listed as NA. CMC Ambroise Paré is the sponsor. The registry description gives clinical context for postoperative diaphragmatic dysfunction and describes ultrasound assessment of diaphragmatic movement. It does not provide further eligibility criteria or a detailed account of rehabilitation delivery.

The primary outcome is the ratio of maximum-inspiration diaphragmatic excursion at Day 5 to excursion at Day 3. Ultrasound measurements were specified separately for the left and right hemidiaphragms. The Day 3 and Day 5 measurements were taken before the first rehabilitation session of the day. The record notes that not all patients had bilateral paresis, which matters when interpreting the side-specific outcome: the analyzed participants could differ between sides.

The registry lists nine outcome measures, including the primary outcome and secondary measures of normal-inspiration excursion, oxygen saturation, non-invasive ventilation, oxygenation, respiratory complications, intensive care unit and hospital length of stay, and pain score. Although the trial is marked completed, the registry record does not report the primary comparison results, secondary outcome results, or analysis details. The posted enrollment describes trial enrollment, not necessarily the number contributing to each side-specific outcome.

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

Analysis population for the primary outcome, as defined in the registry: The analysis was performed separately for the left and right sides, and not all patients had bilateral diaphragmatic paresis.

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 Diaphragmatic Excursion in Maximum Inspiration, measured over Days 3 and 5.

The primary endpoint is diaphragmatic excursion during maximum inspiration, represented as a Day 5-to-Day 3 ratio. Excursion is the displacement of the diaphragm measured by ultrasound in TM mode. The registry describes the underlying Day 3 and Day 5 measurements in millimetres and says the reported outcome is M2max/M1max. A ratio expresses the later measurement relative to the earlier measurement, rather than reporting either measurement alone. The listed unit is “ratio.”

The endpoint was measured separately for the left and right hemidiaphragms. Day 3 measurements were obtained before the first rehabilitation session of the day, as were Day 5 measurements. This timing defines the comparison around an early rehabilitation period and avoids treating measurements taken at different points within a treatment day as interchangeable. The registry does not report the actual ratios, their inter-quartile ranges, or a statistical comparison between groups.

Ultrasound excursion is used in the registry as a measure of diaphragm movement. The study description also uses ultrasound excursion to identify diaphragmatic paresis, with an excursion below 25 mm after deep inspiration for at least one hemidiaphragm. The primary endpoint, however, is a ratio of measurements at two time points, not the diagnostic threshold itself. A ratio can describe relative change while concealing the absolute starting and ending measurements, so the values and their distributions would be useful for clinical interpretation. The record reports median and inter-quartile range as the intended summary, but does not provide those results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the study as randomized, double-masked, and parallel-group. These terms describe features of the design, not the result. Randomization is intended, in general, to distribute measured and unmeasured prognostic characteristics across groups by chance. A parallel-group design assigns participants to a group that receives its assigned approach during the trial rather than having each participant receive both approaches. Masking is intended, in general, to limit the influence of knowledge about assigned treatment on care, outcome assessment, or reporting. The registry record does not describe how these design features were implemented.

What does a median and inter-quartile range describe?

The primary outcome is specified as a median with an inter-quartile range. In general, the median is the central observation after values are ordered. The inter-quartile range describes the spread from the lower to the upper quartile and is less influenced by extreme observations than a range spanning all values. These summaries describe the distribution; they do not alone quantify a treatment contrast or its precision. For that, the group comparison and an uncertainty measure are needed. Those results are not reported in the registry record.

The registry’s selection of median and inter-quartile range indicates the planned descriptive summary, but it does not explain why this summary was selected or name the inferential test. The analysis method, assumptions, handling of repeated or side-specific observations, and any adjustment strategy are not reported in the registry record. It would be inappropriate to infer a particular test from the use of medians.

How should the ratio endpoint be understood?

The primary endpoint is defined as the Day 5 maximum-inspiration excursion divided by the Day 3 maximum-inspiration excursion. In general, a ratio expresses one measurement relative to a reference measurement. This allows a relative change to be described, but makes the result dependent on the reference value. When reference measurements vary, ratios can also have a distribution that is asymmetric. Examining the underlying Day 3 and Day 5 measurements can therefore provide context that a ratio alone cannot.

The record says the ultrasound measurements were obtained before the first rehabilitation session of the day at both time points. This specifies when measurement occurred in relation to that day's session. It does not provide the measurement protocol in enough detail to assess operator training, repeatability, or blinding of the assessor. Those details are not reported in the registry record.

Why do the left and right sides need separate interpretation?

The registry says that the primary analysis was performed separately for the left and right sides and that not all patients had bilateral paresis. In general, measurements from the two sides of one person are related, while the set of participants contributing data can differ by side. Side-specific results therefore need their own denominators and definitions of eligibility. The registry does not report side-specific counts, missing measurements, or whether participants with measurements on both sides were handled in any joint model.

Separate outcome analyses can also raise multiplicity concerns. In general, testing multiple outcomes or comparisons increases the chance of finding an apparently unusual result by chance if no adjustment or prespecified hierarchy is used. The record lists several secondary outcomes and describes separate left- and right-side primary measurements, but it does not report a multiplicity strategy. No particular adjustment should be assumed.

What can confidence intervals contribute?

In general, a confidence interval gives a range of values compatible with the data and the assumptions of the statistical procedure. Its width conveys precision: a narrower interval indicates more precision than a wider interval for the same quantity and method. A confidence interval is not a guarantee that the true effect lies inside it, and it does not replace consideration of the endpoint's clinical meaning. The registry record does not report confidence intervals for the primary outcome.

The sample-size assumptions describe planning illustrations based on an observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such illustrations are not observed power, nor do they establish the trial's original design rationale. The record does not provide the resulting participant-per-arm values for the primary comparison, and it states that the primary outcome has several categories or time points and was not reduced to one comparison. The trial's own sample-size justification is not reported in the registry record.

What analysis details remain unknown?

The registry lists zero analyses. It does not report an inferential model, the exact analysis population, any intention-to-treat or per-protocol approach, covariate adjustment, handling of missing data, or sensitivity analyses. These choices affect what question an estimate answers and how robust it is to incomplete measurements or modeling assumptions. A registry description of the endpoint is not a substitute for those details or for the reported results.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists the maximum-inspiration excursion ratio as the primary outcome and lists secondary outcomes covering normal-inspiration excursion, oxygen saturation, non-invasive ventilation, oxygenation, respiratory complications, intensive care unit and hospital length of stay, and pain score. The primary endpoint is assessed separately for the left and right hemidiaphragms. This creates more than one outcome comparison to interpret, but the registry record does not report a multiplicity plan, a hierarchy among outcomes, or whether any adjustment was used. Without that information, the risk of chance findings across multiple comparisons cannot be assessed.

The record lists zero analyses and does not report outcome estimates or participant counts contributing to the primary endpoint by side. It notes that not all participants had bilateral paresis. Missing outcome data, reasons for missingness, and the method used to handle unavailable measurements are not reported in the registry record. It is also not reported whether the analyses included all randomized participants, only participants with observed measurements, or another analysis population.

In general, missingness can affect interpretation if the availability of an outcome is related to participant status or treatment assignment. Analyses based only on observed measurements may represent a selected subset when missingness is informative. This is a general concern, not a claim that such a pattern occurred in this trial. The registry record does not provide enough information to assess it.

The record also does not state whether the primary analysis adjusted for baseline excursion, how measurements from both sides were accounted for, or whether any sensitivity analyses were performed. Those aspects of the statistical plan are not reported in the registry record, so the robustness of any primary or secondary finding cannot be evaluated from the posted record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The adverse-event figures list zero serious adverse events, zero other adverse events, and zero deaths in the usual-technique group, with 14 at risk for each event category. For the CR-technique group, the figures list zero serious adverse events, zero other adverse events, and zero deaths, with 13 at risk for each category. These are the recorded counts in the registry, not estimates of the probability of an event.

Zero recorded events should not be interpreted as proof that an intervention has no risk. In general, event counts depend on the number of people observed, the length of follow-up, event definitions, and completeness of reporting. The registry record does not describe the adverse-event observation window or provide additional detail about how events were collected or adjudicated. It also lists no serious adverse-event terms.

The “at risk” counts in these figures should not automatically be treated as the denominator for every other endpoint, since outcome availability and analysis populations can differ. The record does not state whether adverse-event reporting covered the full trial period or how missing safety information was handled. These safety figures therefore describe what the registry records, while leaving the scope and precision of safety monitoring unclear.

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

The trial asks a clinically focused statistical question: whether adding Contract-Relax to standard rehabilitation is associated with an early change in ultrasound-measured diaphragmatic excursion after cardiac surgery. The randomized, parallel-group design is relevant to comparing the assigned rehabilitation approaches, and the registry defines the primary endpoint and its measurement timing. The endpoint is a ratio of maximum-inspiration excursion at Day 5 to that at Day 3, analyzed separately for each hemidiaphragm.

What the record does not establish is the observed direction or size of any group difference. The primary outcome values, between-group estimates, uncertainty intervals, and inferential results are not reported in the registry record. It is therefore not possible to determine from this information whether the groups differed, how precisely any difference was estimated, or whether the change was clinically meaningful. Completion status and trial enrollment do not answer those questions.

The primary endpoint is a physiological measure rather than a direct measure of respiratory complications, hospital stay, or patient experience. The registry lists those and other secondary outcomes, but does not report their results. Even a difference in diaphragm excursion would not, by itself, establish a difference in these broader outcomes. Conversely, the absence of reported results in the registry is not evidence that no difference occurred.

The record also leaves important interpretive details unresolved: side-specific analysis counts, the handling of missing measurements, the analysis population, the comparison method, and multiplicity procedures are not reported. The absence of bilateral paresis in some participants means the left- and right-side estimates may reflect different participant sets. The adverse-event figures show no recorded events in either group, but do not establish absence of risk or describe the observation window.

The appropriate conclusion is limited: the registry documents a completed randomized comparison and defines what the investigators intended to measure, but the posted results needed to estimate the treatment contrast are not reported in the registry record. No conclusion about the effect of CR on the primary or secondary outcomes can be drawn from the design description alone.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a focused physiological endpoint can be built around a short interval and a repeated measurement. The primary comparison uses the ratio of maximum-inspiration excursion at Day 5 to excursion at Day 3, with measurements defined in relation to the first rehabilitation session of each day. That definition makes clear what change the endpoint is intended to capture, while also showing why the measurement scale and timing need to be interpreted carefully.

The side-specific design adds an important issue for analysis. The registry says not all participants had bilateral paresis, so the left and right measurements may not come from identical participant sets. Reporting denominators, missingness, and the relationship between bilateral measurements would help readers understand the precision and comparability of the side-specific estimates. Those details are not reported in the registry record.

The study also illustrates the distinction between a registered outcome and a reported result. A named primary outcome does not provide an effect estimate, and a completed status does not show whether the result was precise or clinically important. The registry lists a broad set of respiratory and patient-centred secondary outcomes, but does not report their results or explain how multiple comparisons were addressed.

For clinical researchers, the record makes the intended comparison and endpoint construction visible, but not the analysis needed to evaluate the evidence. Group-specific distributions, a treatment contrast with uncertainty, analysis populations, and missing-data methods would allow the primary question to be assessed more directly. Their absence limits both statistical interpretation and comparison with future studies.

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 main limitation for interpreting this trial from the registry record is that primary and secondary outcome results are not reported. There are no group-specific endpoint summaries, treatment-effect estimates, confidence intervals, or inferential results. The record therefore supports a description of the planned comparison, but not an assessment of its observed magnitude or precision.

Further, the registry does not report the number of participants with usable measurements for each side, the analysis population, or how missing measurements were addressed. This is particularly relevant because the primary outcome was analyzed separately by hemidiaphragm and not all participants had bilateral paresis. The extent to which side-specific findings are comparable cannot be determined.

Although the trial is described as randomized and double-masked, implementation details are not reported. The registry does not describe sequence generation, allocation concealment, who was masked, or whether masking could be maintained during physical therapy. The intervention description “Standard rehabilitation + 3 CR” does not explain what “3 CR” denotes or provide the treatment schedule. These details are not reported in the registry record.

The statistical analysis method, multiplicity strategy, baseline adjustment, and sensitivity analyses are also not reported. The sample-size assumptions describe planning illustrations based on an observed effect, but the original sample-size justification is not reported in the registry record. The adverse-event figures contain zero recorded events in both groups, but the safety observation period and ascertainment procedures are not described. Together, these gaps prevent a full assessment of the trial's analysis, precision, and reporting completeness.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Contract-Relax (CR) Technique in the Management of Diaphragmatic Paresis After Cardiac Surgery — NCT05068219.
• Registry record last updated 2026-06-08; status last verified 2023-12.
• Results first posted 2026-06-08.
• 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

NCT05068219 is a completed, randomized, double-masked, parallel-group trial sponsored by CMC Ambroise Paré. Enrollment is recorded as 27. The comparison is standard rehabilitation alone versus standard rehabilitation plus the Contract-Relax technique for diaphragmatic paresis after cardiac surgery. The trial started on 2021-11-25, and primary completion is recorded as 2023-10-21.

The primary outcome is the Day 5-to-Day 3 ratio of ultrasound-measured diaphragmatic excursion during maximum inspiration, summarized as a median and inter-quartile range and assessed separately for left and right hemidiaphragms. The registry lists secondary respiratory, length-of-stay, and pain outcomes. It records zero serious adverse events, zero other adverse events, and zero deaths in both groups.

Primary and secondary outcome results, analysis methods, missing-data handling, analysis populations, and multiplicity procedures are not reported in the registry record. The registry therefore describes the trial question and design but does not provide the results needed to estimate the intervention contrast.