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 Validation of RPVi as a Parameter to Predict Fluid Responsiveness (NCT03706430), a na phase not stated study. The primary outcome is Comparison of RPVi to SVV and/or PPV.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03706430 |
| Phase | Phase not stated |
| Condition | Surgery, Anesthesia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 63 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Masimo Corporation |
| Results posted | Yes |
2. Clinical Question
Population
The intended population was people undergoing surgery, with measurements collected during surgery over approximately 2-6 hours. The registry record says zero subjects were collected for validation because the study was terminated during data collection due to slow enrollment. Although the record lists an enrollment of 63, that figure does not represent a validation dataset: the primary-outcome description explicitly reports that no subjects were collected for validation.
Intervention
All subjects were assigned to a single group and were to receive an investigational pulse CO-Oximeter sensor. The study was designed to evaluate RPVi, a parameter recorded in relation to this sensor, as a way to predict fluid responsiveness. The registry record does not provide further details about measurement procedures or how fluid responsiveness was established.
Comparator
The intended comparison was with other dynamic parameters, specifically stroke volume variation (SVV) and/or pulse pressure variation (PPV). This was not a randomized, parallel-group comparison of treatments. The design is listed as single group, with allocation recorded as NA; the comparator was therefore a set of measurements or parameters, not a separate control arm.
Primary question
The primary question was whether RPVi could predict fluid responsiveness in comparison with SVV and/or PPV, using Bland Altman analysis. Because no subjects were collected for validation, the record reports no comparative endpoint results. It therefore does not establish the predictive performance of RPVi or how closely it agrees with the other parameters.
3. Trial Design
This was a prospective, nonrandomized, sequential data collection study sponsored by Masimo Corporation. The registry identifies the model as single group and the allocation as NA. All subjects were to receive an investigational pulse CO-Oximeter sensor; there was no randomized assignment to a separate control group. The planned comparison concerned RPVi and other dynamic parameters, including SVV and/or PPV.
The study record gives an enrollment of 63, but its primary-outcome description states that zero subjects were collected for validation. It also says the study was terminated during the data collection phase due to slow enrollment. These entries describe different aspects of the record: the enrollment field does not supply an analyzable validation population when the outcome description explicitly says no subjects were collected for validation. The registry record does not explain the enrollment figure’s relationship to that statement.
The recorded start date is 2018-09-24, and the primary completion date is 2021-10-20. The status is terminated. The planned observation period for the primary comparison was approximately 2-6 hours during surgery. The record does not report a detailed protocol for the sequence of measurements, the criteria used to identify fluid responsiveness, or the handling of measurements taken at different times.
Since the study had no randomized treatment comparison and no validation subjects, its record cannot support conclusions about comparative treatment effects or measured predictive performance. The planned design instead sought to assess a monitoring parameter against other dynamic parameters. Additional details about the statistical plan, recruitment targets, and reasons for the slow enrollment beyond the stated termination explanation are not reported in the registry record.
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 | Pulse Co-Oximeter Sensor |
|---|---|
| STARTED | 63 |
| COMPLETED | 48 |
| NOT COMPLETED | 15 |
Reasons for not completing this period:
| Reason | Pulse Co-Oximeter Sensor |
|---|---|
| No A-Line placed | 5 |
| Subject had gel nail polish | 1 |
| Nail length causing difficulties with sensor | 1 |
| Cancelled Case | 6 |
| Physician Decision | 2 |
Analysis population for the primary outcome, as defined in the registry: Zero subjects were collected for validation as the study was terminated in the data collection phase due to slow enrollment
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 | Pulse Co-Oximeter Sensor |
|---|---|---|
| Participants analysed | 48 | |
| Age, Customized: ≤ 18 years | Participants | 0 |
| Age, Customized: Between 18 and 65 years | Participants | 23 |
| Age, Customized: ≥ 65 years | Participants | 25 |
| Sex: Female, Male: Female | Participants | 15 |
| Sex: Female, Male: Male | Participants | 33 |
| Race/Ethnicity, Customized: American Indian or Alaskan Native | Participants | 0 |
| Race/Ethnicity, Customized: Asian | Participants | 4 |
| Race/Ethnicity, Customized: Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race/Ethnicity, Customized: Black or African American | Participants | 1 |
| Race/Ethnicity, Customized: White | Participants | 38 |
| Race/Ethnicity, Customized: Unknown or Not Reported | Participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Comparison of RPVi to SVV and/or PPV, measured over approximately 2-6 hours during surgery.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary outcome was titled “Comparison of RPVi to SVV and/or PPV.” It was intended to evaluate how well RPVi predicts fluid responsiveness relative to stroke volume variation (SVV) and/or pulse pressure variation (PPV), using Bland Altman analysis. The planned timeframe was approximately 2-6 hours during surgery.
In general, fluid responsiveness describes whether a person’s cardiovascular response changes following a fluid-related intervention. Dynamic parameters such as those named in the record are intended to inform that assessment. Comparing RPVi with SVV and/or PPV could therefore help evaluate whether the parameters give similar or different information. The registry record does not define the operational criteria for fluid responsiveness, specify which comparator or comparators were to be used for each participant, or explain how the analysis would translate parameter agreement into prediction performance.
Bland–Altman analysis is generally used to examine agreement between measurement methods by assessing the differences between paired measurements in relation to their average. It can help identify systematic differences and the spread of individual differences, which are relevant when considering whether two methods can be used interchangeably. Agreement is not, by itself, the same as prediction accuracy against an independently defined clinical outcome; interpretation depends on the measurement context and prespecified acceptable limits.
No subjects were collected for validation, and no numerical endpoint results are reported. The record therefore gives the intended measurement question and method, but not an estimate of agreement, predictive ability, or uncertainty.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record documents an intended evaluation, not a completed validation result. Its primary-outcome description says zero subjects were collected for validation and attributes termination during data collection to slow enrollment. As a result, no comparative values are reported for RPVi versus SVV and/or PPV, and the record offers no estimate of how accurately RPVi predicts fluid responsiveness.
The enrollment field lists 63. That entry should not be treated as the number of subjects contributing to the primary validation analysis: the outcome description explicitly says that no subjects were collected for validation. The registry does not explain how the enrollment entry relates to the stated absence of validation subjects. The difference should therefore be left unresolved rather than interpreted as a participant count for the endpoint.
The planned use of Bland Altman analysis does not imply that an agreement analysis was completed. No reported results describe the direction or magnitude of differences between methods, their variability, or any limits of agreement. No confidence interval or other measure of precision for the primary comparison is reported. Without such information, readers cannot assess whether any observed agreement would be sufficiently precise or clinically meaningful.
This is also not a comparison of randomized treatment groups. All subjects were to receive the sensor in a single group, while the comparison involved physiological parameters. Accordingly, the record cannot be read as evidence for a treatment benefit or harm. The study’s stated question concerns prediction and measurement comparison, and even that question remains unanswered by the reported validation data.
The status is terminated, and the record states that termination occurred during data collection because enrollment was slow. The registry does not report whether any preliminary measurements were obtained for purposes other than validation, whether an interim analysis occurred, or whether any analyses were performed before termination. It lists one outcome measure and zero analyses. Those record entries do not provide evidence of an unreported completed analysis.
For readers interpreting the study, the appropriate conclusion is limited: a validation study was planned, with a specified comparator framework and analysis approach, but the registry reports no validation subjects and no endpoint results. This absence of results is not evidence that RPVi performs well or poorly. It means the record cannot quantify its performance or support a conclusion about agreement with SVV and/or PPV.
9. Statistical Methods Explained
The record names Bland Altman analysis as the method for the primary comparison. It does not report results from that analysis, and the primary-outcome description states that zero subjects were collected for validation. The following explanation describes the method in general; it should not be read as a report that the planned analysis was carried out.
What does Bland–Altman analysis assess?
In general, Bland–Altman analysis evaluates agreement between two methods that measure or estimate the same quantity. It examines paired readings by considering their differences alongside their averages. The average difference can indicate whether one method tends to read higher or lower than the other. The spread of the differences describes how much individual paired readings vary around that average.
Agreement matters because two methods can be associated with one another yet still produce readings that differ enough to be unsuitable substitutes. A high correlation, for example, does not alone show that the readings agree closely: one method might consistently differ from another, or the difference might vary substantially across observations. Bland–Altman methods focus on those differences rather than relying only on correlation.
In general, an agreement analysis may report a mean difference and limits describing the range in which differences are expected to fall. Confidence intervals can express uncertainty around these estimates. Acceptable limits should be considered in the context of the intended use, and ideally defined before examining results. The registry record does not report estimates, confidence intervals, acceptable limits, or whether any such limits were prespecified.
How does this relate to prediction?
The stated aim was to evaluate RPVi’s ability to predict fluid responsiveness in comparison with SVV and/or PPV. Agreement between parameters can be relevant to that aim, but agreement and prediction are not identical concepts. Agreement describes how closely two measurement methods yield comparable values. Prediction asks how well a measure identifies or forecasts a target outcome. To interpret predictive performance, it is important to know how the target condition was defined and assessed, and what performance criteria were planned. Those details are not reported in the registry record.
The description names SVV and/or PPV but does not specify which comparator would be used in each analysis, whether comparisons were to be paired at the same time points, or how repeated measurements would be handled. The intended collection was sequential and took place over approximately 2-6 hours during surgery. Repeated observations within a person are generally related rather than independent. Statistical methods should account for such dependence when it is relevant, but the registry record does not state how repeated measurements were to be modeled.
Why can measurement variability matter?
As a general statistical principle, measurement error and natural variation can widen the differences between methods. If variability differs across the range of readings, a single summary of the average difference may not describe agreement equally well throughout that range. A transformation or other approach may sometimes be considered, depending on the data and the scientific question. No distributional checks, transformations, or alternative analyses are reported in the registry record.
Over-dispersion is a general issue in some data settings: observed variability can exceed what a chosen statistical model assumes. When that happens, standard errors and confidence intervals from a model that understates variability may be misleading. Whether over-dispersion is relevant depends on the outcome type and model. The registry record does not report an outcome distribution, model, or assessment of over-dispersion, so no conclusion about its presence or handling can be made.
What can be concluded from the method entry?
The method entry identifies the intended analytical framework, but a method name is not a result. An informative completed analysis would ordinarily need paired measurements, clear definitions of the quantities compared, estimates of differences and their uncertainty, and a reasoned interpretation of acceptable agreement for the intended use. The registry record reports none of those results and states that no validation subjects were collected.
The record lists one outcome measure and zero analyses. It does not report a detailed statistical analysis plan, a sample-size justification, interim analyses, or procedures for missing observations. Such information is not reported in the registry record. In the absence of endpoint data, no statistical significance test, confidence interval, effect estimate, or model-based conclusion can be interpreted for the primary question.
Any sample-size values displayed elsewhere as planning illustrations should be understood as hypothetical design calculations, not findings from this study. The stated illustration assumptions are 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 an observed effect. The record’s general note distinguishes total events for time-to-event illustrations from participants per arm for other illustrations. These assumptions do not describe the trial’s own design, and the single-group study was not a two-arm randomized comparison. Such planning figures are not observed power and cannot compensate for the absence of validation data.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and zero analyses. It names a primary comparison of RPVi with SVV and/or PPV, but does not report a complete statistical analysis plan. It is therefore not possible to determine whether multiple comparisons, multiple time points, or alternative definitions of fluid responsiveness were planned, or whether any multiplicity adjustment was intended. Details on these matters are not reported in the registry record.
The record does not describe missing-data procedures, rules for excluding observations, or how incomplete measurement sequences would have been handled. More fundamentally, the primary-outcome description states that zero subjects were collected for validation. There are consequently no reported endpoint observations from which to assess missingness or conduct the stated validation comparison.
Analysis populations are not defined in the record. It does not specify an analysis set for paired measurements or report whether any participants were included in other analyses. The enrollment field lists 63, while the outcome description reports zero validation subjects; the registry does not explain the relationship between these entries. No analysis population should be inferred from the enrollment field alone.
The registry record also does not report an interim-analysis plan, stopping rules, or a sample-size justification for the study. Its stated reason for termination is slow enrollment during data collection. Without further detail, the effects of early termination on planned analyses cannot be quantified.
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 |
|---|---|---|---|
| Pulse Co-Oximeter Sensor | 0 | 48 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Pulse Co-Oximeter Sensor | 0 of 48 |
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 |
|---|---|
| Pulse Co-Oximeter Sensor | 0 of 48 |
The adverse-event entry lists the Pulse Co-Oximeter Sensor group with 48 at risk for serious adverse events and zero affected. It also lists 48 at risk for other adverse events and zero affected. The record lists zero deaths, and no top serious-event terms are reported.
These entries describe the safety information recorded in the registry; they should not be interpreted as proof that no adverse events occurred in every person exposed to the sensor. The registry does not explain the relationship between the 48 people listed at risk and the enrollment field of 63, nor does it give further detail about safety ascertainment or reporting. The zero-validation statement applies specifically to the primary validation outcome and does not, by itself, resolve how the safety figures were collected.
Because this was a single-group study, the safety figures do not provide a randomized comparison with a control group. They cannot establish whether an event rate differs from another intervention or from usual care. The record also does not report event descriptions beyond the listed counts. These figures should therefore be read as the registry’s reported safety entries, with the limited context available.
12. What the Result Does, and Does Not, Mean
This record establishes that a prospective, nonrandomized study was planned to compare RPVi with SVV and/or PPV for predicting fluid responsiveness during surgery. It identifies the intended sensor, a measurement period of approximately 2-6 hours, and Bland Altman analysis as the planned method. It also records that the study was terminated during data collection due to slow enrollment.
It does not establish whether RPVi predicts fluid responsiveness accurately, whether it agrees with SVV or PPV, or whether any differences would be acceptable for a particular use. No subjects were collected for validation, and no primary endpoint results are reported. Thus there is no effect estimate, agreement estimate, or precision measure in the registry record to support a positive or negative judgment about performance.
The absence of validation results is not a finding that RPVi has no predictive value. Nor does the study’s stated aim demonstrate that RPVi is useful. The data needed to answer the planned question are not reported. The enrollment entry of 63 should not be substituted for a validation sample, because the endpoint description explicitly states that zero subjects were collected for validation; the registry does not reconcile those entries.
The safety entries report zero serious adverse events and zero other adverse events among the listed group, with zero deaths. Those figures are limited to the registry’s recorded information and do not turn the study into a controlled safety comparison. The record does not provide enough detail to interpret them beyond their stated counts.
In practical statistical terms, this is an incomplete validation record rather than a completed performance assessment. It can inform readers about the intended research question and why the study stopped, but not about the magnitude, precision, or clinical relevance of the proposed comparison.
13. Why This Trial Matters Statistically
The study’s statistical question is meaningful because monitoring parameters are often evaluated not only by whether they move together, but by whether their readings agree closely enough for the intended purpose. The proposed comparison of RPVi with SVV and/or PPV therefore raises a measurement-agreement question as well as a prediction question. Distinguishing those concepts is important when interpreting any future validation evidence.
The record also illustrates why a registry status and a stated enrollment field should not be mistaken for completed evidence. Although the enrollment field lists 63, the primary-outcome description reports zero subjects collected for validation. No endpoint estimates or analyses are recorded. That makes the distinction between administrative enrollment information and the analyzable population particularly important for readers.
Early termination due to slow enrollment can leave a planned research question unanswered. When no validation subjects are reported, there is no basis for estimating agreement, precision, or predictive performance. A planned statistical method, even one named in the record, cannot provide evidence in the absence of analyzed data.
The record is also a reminder that a comparison of physiological parameters differs from a randomized treatment comparison. Here, the single-group design was intended to compare measurements, not to allocate participants to competing treatments. Interpreting the study in terms of treatment effects would therefore misstate its purpose.
For biostatisticians and clinical researchers, the main statistical lesson is to separate study intent, recorded enrollment, analysis population, and results. The registry describes the first and gives limited information about the others, but it reports no completed validation result. That boundary should guide any interpretation.
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 is that the registry reports zero subjects collected for validation. Without validation observations, the primary comparison cannot yield reported estimates of agreement or prediction performance. The study was terminated during data collection, with slow enrollment given as the reason.
The enrollment field lists 63, but the primary-outcome description says no subjects were collected for validation. The registry record does not explain the relationship between these entries. This prevents a clear account of how many participants, if any, contributed to other data collection or safety reporting, and the enrollment figure should not be taken as the validation analysis population.
The record provides limited methodological detail. It does not define fluid responsiveness, specify how it was assessed, identify which comparator or comparators would be used in each analysis, or explain how sequential and potentially repeated measurements were to be handled. Although Bland Altman analysis is named, the record does not report its specific implementation, acceptable agreement criteria, or results.
A detailed statistical plan, sample-size justification, missing-data strategy, analysis populations, and interim-analysis information are not reported in the registry record. The record also does not explain the safety reporting population or reconcile its at-risk count with the enrollment entry. These limitations restrict interpretation of both the intended endpoint and the safety figures.
The design was single group and nonrandomized, so it was not structured as a randomized comparison of treatments. More importantly for the stated measurement question, no validation dataset is reported. Consequently, the record cannot support a quantitative conclusion about RPVi’s performance or its agreement with SVV and/or PPV.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Validation of RPVi as a Parameter to Predict Fluid Responsiveness — NCT03706430.
- Registry record last updated 2026-06-18; status last verified 2026-05.
- Results first posted 2023-06-22.
- 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
NCT03706430 is a prospective, nonrandomized, single-group study sponsored by Masimo Corporation. It was intended to evaluate RPVi as a predictor of fluid responsiveness in comparison with SVV and/or PPV, using Bland Altman analysis during approximately 2-6 hours of surgery. All subjects were to receive an investigational pulse CO-Oximeter sensor.
The registry lists an enrollment of 63, but the primary-outcome description states that zero subjects were collected for validation. The study was terminated during data collection due to slow enrollment. No primary endpoint results or analyses are reported. The record lists zero serious adverse events, zero other adverse events, and zero deaths among the reported safety entries, with 48 at risk for each adverse-event category.
The study’s intended question remains unanswered in the registry record. It does not provide evidence for or against RPVi’s predictive performance or agreement with the comparator parameters.