Hemodynamic Response During Goal Directed Fluid Therapy in the OR: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hemodynamic Response During Goal Directed Fluid Therapy in the OR (NCT02365688), a na na study. The primary outcome is Dynamic Hemodynamic Response to Fluid Resuscitation.

2. Clinical Question

The study’s stated purpose was to evaluate the response after establishing a pre-incision baseline. Its focus was measurement and monitoring during open abdominal surgery, rather than a comparison of assigned treatment strategies. The registry describes goal-directed fluid therapy as standard care in this setting, but does not report the specific clinical decisions made for individual participants or the amount of fluid beyond the initial bolus procedure.

The record does not establish whether one monitoring modality agreed with another, whether any modality tracked changes more closely, or whether a particular response threshold was met. Those findings are not reported in the registry record. The endpoint description instead identifies a central measurement problem: disagreement among reference devices meant the algorithm could not be verified. The clinical question is therefore best understood as an assessment of monitoring and response measurement, with no interpretable efficacy comparison reported.

3. Trial Design

This was a single-group study with allocation listed as NA and masking listed as none. The registry records enrollment of 18 and status as terminated. The phase is listed as NA. The record gives a start date of 2014-09 and a primary completion date of 2015-06. It does not explain why the study was terminated.

The intervention was a procedure titled “Initial bolus pre-incision.” Its description specifies an initial pre-incision bolus of 500 cc of fluids with hemodynamic response recorded. The study summary describes a retrospective evaluation of hemodynamic response during open abdominal surgery, after establishing a pre-incision baseline response to fluids. The timeframe for the primary outcome was up to 6 hours, but not beyond the duration of the surgical procedure.

The record describes physiological parameters being compared before and after the fluid bolus. It does not identify a separate untreated or alternative-treatment group. A before-and-after observation within a single group is not a randomized comparison, and any changes observed around the bolus could not, by themselves, isolate the bolus as the cause. The registry’s explicit note that reference devices disagreed also limits interpretation of the intended monitoring algorithm.

The sponsor is Medtronic - MITG. More detail on recruitment, eligibility, operative procedures, monitoring-device identities, fluid-management decisions, protocol deviations, and reasons for termination is not reported in the registry record. The record also does not give a statistical analysis plan, sample-size justification, or explanation of whether the retrospective evaluation followed a prespecified protocol. Those omissions prevent a fuller assessment of how the intended measurement question was translated into analysis.

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: Reference devices were in disagreement so the algorithm could not be verified

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Self hemodynamic baseline before surgical incision.

6. Primary Endpoint

The registry lists the primary outcome as Dynamic Hemodynamic Response to Fluid Resuscitation, measured over Up to 6 hours but not to exceed duration of surgical procedure.

The primary outcome is titled “Dynamic Hemodynamic Response to Fluid Resuscitation.” Its description says physiological parameters were compared before and after a fluid bolus, with a timeframe of up to 6 hours but not beyond the duration of the surgical procedure. The outcome does not name the physiological parameters, specify their units, or define a numerical response threshold. Those details are not reported in the registry record.

In general, a before-and-after endpoint can describe how measured physiology changes around an intervention. In a monitoring study, such measurements may also be used to assess whether devices capture a consistent response. That purpose is relevant to the registered question about invasive and non-invasive hemodynamic modalities. However, a change in a physiological measure is not automatically evidence that the intervention caused the change, especially when there is no separate control group and other influences may occur during surgery.

The registry’s outcome population states that reference devices were in disagreement, so the algorithm could not be verified. No endpoint values, change estimates, variability measures, or analysis results are reported. Thus, the endpoint’s purpose is identifiable, but its observed result and measurement precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical methods that were actually used are not described in the registry record. No analysis results are posted, and the registry lists 0 analyses. The outcome description gives a before-and-after measurement objective, but does not name a statistical test, model, adjustment strategy, or decision threshold. The methods below explain relevant statistical ideas in general terms; they should not be read as a claim that these methods were used in this study.

What does a before-and-after comparison describe?

A before-and-after comparison measures an outcome at two points associated with an intervention and describes how the measurements differ. When measurements come from the same individual, the statistical analysis can account for their pairing. Pairing can make the comparison more informative by focusing on within-person change rather than treating observations as unrelated. The registry does not report participant-level measurements, how observations were paired, or whether an analysis of within-person change was performed.

Even when a within-person change is measured accurately, it is not necessarily a causal treatment effect. Conditions can change over time, and other care or events may occur between measurements. A separate, appropriate comparison group can help distinguish changes associated with treatment from changes that might have happened anyway. This study is described as single group, with allocation listed as NA; a separate control group is not reported.

What is the distinction between correlation and agreement?

Correlation describes how two measurements vary together. Agreement asks whether two methods give sufficiently similar values for the intended use. Two devices can have a strong correlation while still giving systematically different readings; correlation alone does not establish that their values can be used interchangeably. In general, a device-comparison study may need to assess both association and agreement, with methods suited to the measurement question.

This distinction matters because the study title refers to correlation across multiple hemodynamic monitoring modalities, while the primary outcome population says reference devices disagreed and the algorithm could not be verified. The record does not report correlation estimates, agreement limits, device-specific results, or the criteria used to judge verification. It is therefore not possible to determine whether the disagreement was systematic, variable, clinically important, or concentrated in particular measurements.

Why do uncertainty estimates matter?

A confidence interval is a general statistical tool for expressing uncertainty around an estimated quantity. It gives a range of values compatible with the data under the assumptions of the analysis. It does not guarantee that the true value lies in the interval, nor does it resolve bias from design limitations or measurement error. No confidence interval or other uncertainty estimate for the primary outcome is reported in the registry record.

Measurement disagreement can contribute uncertainty before any statistical test is considered. If reference measurements are not sufficiently consistent for the intended purpose, a calculated association or change may not establish that the monitoring algorithm has been validated. Statistical precision and measurement validity are related but different questions: an estimate can be precise yet fail to measure the intended quantity reliably.

What would an analysis plan clarify?

A statistical analysis plan typically specifies the outcome definition, analysis population, handling of repeated or missing measurements, model or test, and how uncertainty will be reported. These choices matter because different reasonable approaches can produce different estimates, particularly when observations are repeated, incomplete, or affected by measurement disagreement. The registry does not report such a plan or identify the analysis population.

The record identifies one outcome measure but does not describe whether multiple physiological parameters or monitoring comparisons were treated as separate analyses. The number and structure of those comparisons, and any adjustment for multiple testing, are not reported. Without that information, the risk of selectively emphasizing particular results cannot be assessed from the registry record.

How should planning illustrations be read?

Sample-size calculations are planning tools: they describe how much information a future study might need under stated assumptions about the effect, variability, allocation, and analysis. A planning illustration based on an observed effect is not the same as evidence that the original study had adequate power. It is also not “observed power,” which is not a substitute for reporting the estimate and its uncertainty.

The planning assumptions associated with the record describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect framed as a stated fraction of an observed effect. Time-to-event planning uses total events; other planning outputs are expressed as participants per arm. These are assumptions for an illustration, not evidence that the trial was designed or conducted with two randomized arms. The actual study is registered as single group, and its allocation is NA. The registry does not report its own sample-size justification, so the planning assumptions should not be mistaken for the trial’s protocol.

Because the record reports no verified primary effect estimate or analysis results, a sample-size illustration cannot establish how precisely the study measured a response. Any conclusions about statistical power, detectable effects, or adequacy of enrollment would require information not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies 1 outcome measure, titled “Dynamic Hemodynamic Response to Fluid Resuscitation,” and lists 0 analyses. The outcome description refers to physiological parameters and to multiple monitoring modalities, but does not specify how many parameters or device comparisons were analyzed. The number of statistical tests is therefore not reported in the registry record.

Multiplicity arises when several outcomes, time points, subgroups, or comparisons are tested. In general, conducting many tests can increase the chance of finding an apparently notable result by chance. Researchers may address this through prespecified primary comparisons, adjustment procedures, or careful interpretation of exploratory analyses. The registry does not report whether any multiplicity strategy was planned or used. It also does not state whether a single primary analysis was prespecified despite the broader monitoring question.

Missing-data handling is not reported in the registry record. The record does not describe whether every participant had usable measurements before and after the bolus, how unavailable device readings were handled, or whether any observations were excluded. The analysis population is also not reported. Enrollment of 18 does not establish how many participants contributed to a particular endpoint analysis.

These gaps matter because measurement disagreement may be connected to whether readings are usable or interpretable. Without analysis-population definitions, missing-data rules, and analysis results, readers cannot evaluate whether the reported evidence—if any was analyzed—represents all enrolled participants or a selected subset. No conclusions about missingness, multiplicity, or robustness can be drawn from the registry record.

11. 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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: hypertension (5.6%), blood loss (5.6%).

The registry lists a “Pre-surgical Bolus” group with 18 participants at risk for serious adverse events and 2 serious adverse events. It lists 18 at risk for other adverse events and 0 other adverse events. The record’s most common serious adverse event terms are hypertension and blood loss, each listed at 5.6%.

These figures should be read as registry-reported safety counts, not as evidence that the bolus caused an event. The record does not provide event narratives, timing, severity grading details, attribution to the procedure, or a comparison group. It also does not clarify how the listed event terms relate to the aggregate serious-event count. A term percentage is not a treatment-effect estimate and does not establish causality.

The death count is not reported in the registry record. This is different from a reported count of none. The available figures do not allow comparison with another treatment or assessment of comparative safety. Interpretation is also limited by the single-group design and by the absence of detailed safety follow-up information.

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

The record documents a study intended to examine hemodynamic responses to an initial pre-incision fluid bolus and the relationship among monitoring modalities during open abdominal surgery. It records that reference devices were in disagreement, preventing verification of the algorithm. It does not post a numerical response estimate, a modality correlation, or an uncertainty measure.

That absence means the registry cannot establish the size or precision of any change in physiological parameters. It also cannot establish whether invasive and non-invasive modalities agreed, whether one tracked a response more reliably, or whether the algorithm was valid. The endpoint’s measurement purpose is clear, but its quantitative result is not reported in the registry record.

The single-group, unmasked design does not offer a randomized treatment comparison. Even if a pre-to-post change had been posted, it would not by itself show that the bolus caused the change. Changes during an operation may coincide with other influences, and a control comparison would be needed to address some of those alternatives.

The record should not be read as establishing that goal-directed fluid therapy is effective or ineffective, nor as establishing that any monitoring modality is suitable or unsuitable for clinical use. It reports a measurement challenge, not a comparative clinical outcome. The safety counts are descriptive and do not establish that an event was caused by the procedure. The reason for termination and the disposition of any unposted analyses are not reported in the registry record.

The most defensible interpretation is therefore limited: this registry entry describes a single-group study of perioperative hemodynamic monitoring, and its recorded primary-outcome note says the reference devices disagreed, so the algorithm could not be verified. Claims about clinical benefit, harm, device performance, or reproducibility would go beyond the reported information.

13. Why This Trial Matters Statistically

This study matters statistically because it illustrates that a clinical measurement question depends on the quality and consistency of the reference measurements. An algorithm cannot be meaningfully verified against reference devices if those devices disagree in ways that have not been characterized. The record identifies this problem directly, making measurement validity central to interpretation rather than a technical detail.

It also highlights the difference between correlation and agreement. Correlation can describe whether measurements move together, but it does not show that they are close enough to be interchangeable. For clinical monitoring, the intended use determines what level and type of agreement matters. The registry does not report the device-level estimates or verification criteria needed to judge that issue.

The single-group design also clarifies the limits of before-and-after evidence. Such observations can be useful for describing response around an intervention, but without a control comparison they cannot separate an intervention-associated change from other changes over time. Here, no numerical before-and-after result is posted, so even a descriptive response cannot be assessed.

Finally, the record shows why transparent reporting of outcome definitions, analysis populations, missing-data handling, and statistical methods is important. The registry lists one outcome measure and no analyses, while details needed to evaluate the endpoint are not reported. This leaves uncertainty about what was measured, how it was analyzed, and how the study’s termination affected the evidence. The statistical importance is not a claim about treatment benefit; it is the need to establish reliable measurement and report the analysis clearly.

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 no analysis results are posted. Although the primary outcome describes a before-and-after comparison, the record provides no physiological values, effect estimate, variability measure, or confidence interval. The size and precision of any response therefore cannot be assessed.

The outcome description does not identify the specific physiological parameters, their units, or a threshold for a meaningful response. The record also does not name the monitoring devices, explain how reference devices were selected, describe the nature of their disagreement, or state the criteria for algorithm verification. These omissions prevent evaluation of the measurement process that underpins the study’s main question.

The single-group design, allocation listed as NA, and absence of masking limit causal interpretation and make the study unsuitable as a like-for-like treatment comparison. The registry does not report an analysis population, missing-data procedures, multiplicity strategy, or statistical analysis plan. It is also not clear how many of the enrolled participants contributed usable measurements to the primary outcome.

The record lists the study as terminated but does not give a reason. It does not report whether termination affected recruitment, follow-up, data collection, or analysis. Eligibility criteria, participant characteristics, procedural details beyond the initial bolus, and reasons for any unavailable measurements are not reported in the registry record. Together, these limits leave the study’s intended measurement question understandable but its evidential result unresolved.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Hemodynamic Response During Goal Directed Fluid Therapy in the OR — NCT02365688.
• Registry record last updated 2017-07-18; status last verified 2017-06.
• Results first posted 2016-05-23.
• 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.

18. Record Summary

The registry record describes NCT02365688, “Hemodynamic Response During Goal Directed Fluid Therapy in the OR,” with the official title “Correlation of Multiple Invasive and Non-Invasive Hemodynamic Monitored Modalities to Support Goal Directed Fluid Therapy During Open Abdominal Surgery.” The study is listed as single group, with allocation NA and masking none. Enrollment is 18, and status is terminated.

The registered procedure was an initial pre-incision bolus of 500 cc of fluids, with hemodynamic response recorded. The primary outcome concerned physiological parameters before and after fluid resuscitation, over up to 6 hours but not beyond the surgical procedure. The registry states that reference devices disagreed, so the algorithm could not be verified. It lists 1 outcome measure and 0 analyses.

The sponsor is Medtronic - MITG. The record gives a start date of 2014-09 and a primary completion date of 2015-06. The reason for termination, analysis results, and statistical analysis plan are not reported in the registry record.