Predict Fluid Responsiveness in Spinal Anesthesia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Predict Fluid Responsiveness in Spinal Anesthesia (NCT02070276), a randomized na study. The primary outcome is Percentage of Participants With Systemic Hypotensions.

2. Clinical Question

The clinical question was whether using non-invasive assessments of fluid responsiveness to guide preventive fluid administration before spinal anesthesia was associated with a different rate of significant systemic hypotension than standard clinical practice. The registry describes the rationale as concern that empiric fluid administration may not reflect an individual patient’s hemodynamic status and may risk volume overload.

The registry presents the two strategies as separate arms rather than as a combined intervention. The comparisons therefore address each assessment method against the standard-practice control. They do not directly compare echocardiography with the Passive Leg Raising Test. The record frames the objective around hypotension prevention, but the posted outcome data describe group results and do not establish that any observed difference was caused by the intervention.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group trial. It lists enrollment of 429 and a completed status. The listed study start is 2014-05, and the primary completion date is 2019-02. The sponsor is Ente Ospedaliero Cantonale, Bellinzona. The phase is listed as NA.

Three arms are described. Arm A is Standard Clinical Practice and serves as the control. Arm B is the trans-thoracic echocardiography arm; its description says the assessment was added to standard clinical practice to assess volume status and fluid responsiveness. Arm C is the Passive Leg Raising Test arm; its description likewise places the test in addition to standard practice and mentions measuring end-tidal CO2. The registry describes random allocation, but the method used to generate or conceal the allocation sequence is not reported in the registry record.

Masking is listed as single, but the identity of the masked party and the practical masking procedures are not reported in the registry record. The parallel model indicates separate intervention groups rather than a crossover design. The record lists 149 participants in Arm A, 132 in Arm B, and 148 in Arm C for the primary outcome. These are the arm-level outcome counts used in the posted comparisons; the registry does not provide a detailed account of exclusions, missing outcomes, or the analysis population.

The listed secondary outcomes are pre-anesthesia and post-anesthesia fluid amount. The registry reports no formal analyses for these outcomes and lists no analyses overall. The original sample-size justification, trial-specific statistical analysis plan, and details of any interim analyses are not reported in the registry record. The available descriptions therefore support an account of the broad design and recorded outcomes, but not a reconstruction of all conduct or analysis decisions.

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.

Before assignment: Study began at the arrival in the operating block and ended 30 minutes after completion of spinal anaesthesia. The pre-anaesthetic phase running from time 0 to the beginning of spinal anaesthesia, the anaesthetic phase which corresponds to spinal anaesthesia gesture, followed by the post-anaesthetic phase ending 30 minutes spinal anaesthesia

Overall Study

Analysis population for the primary outcome, as defined in the registry: Participants with Systemic Hypotensions

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 Percentage of Participants With Systemic Hypotensions, measured over 30 minutes.

The primary endpoint is the number of participants recorded as having systemic hypotension, with the timeframe specified as 30 minutes. The registry title describes the outcome as the percentage of participants with systemic hypotensions, while the posted arm results give participant counts. The outcome description defines arterial hypotension using any of the listed criteria: a systolic blood pressure drop over 50 mmHg from baseline, an absolute systolic blood pressure value less than 80 mm Hg, a mean arterial pressure below 60 mmHg, or clinically symptomatic hypotension. The symptoms named are dizziness, pallor, sweating, and nausea.

This endpoint is used because the study objective concerns significant hypotension after spinal anesthesia. A binary event outcome records whether each participant meets the specified definition during the stated observation period; it does not show the duration or severity of an event, nor which criterion triggered classification. The registry does not report separate results for each criterion, event timing within the 30-minute period, or a fuller account of how measurements and symptoms were adjudicated.

Interpretation depends on the operational definition and observation window. The endpoint is not a general measure of all blood-pressure changes, fluid status, or longer-term outcomes. It captures the defined systemic hypotension outcome in the reported timeframe, so conclusions should remain focused on that event rather than extend to unreported clinical outcomes.

7. Results Posted in the Registry

• Arm B: 34.8% (46/132) versus 45.6% (68/149) on control; risk difference -10.8 percentage points (95% CI -22.2 to 0.6), risk ratio 0.76 (0.57–1.02); unadjusted two-proportion z-test p = 0.066.
• Arm C: 43.9% (65/148) versus 45.6% (68/149) on control; risk difference -1.7 percentage points (95% CI -13.0 to 9.6), risk ratio 0.96 (0.75–1.24); unadjusted two-proportion z-test p = 0.766.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Pre-anesthesia Fluid Amount

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Arm B: mean 336.00 versus 141.00 on control; difference 195.00 (95% CI 137.21 to 252.79), standardized effect d = 0.82; z-test p = <0.001.
  • Arm C: mean 168.00 versus 141.00 on control; difference 27.00 (95% CI -16.91 to 70.91), standardized effect d = 0.14; z-test p = 0.228.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Arm B than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Arm C and the control. The interval gives the range of effects that remain compatible with the data.

Post-anesthesia Fluid Amount

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Arm B: mean 257.00 versus 312.00 on control; difference -55.00 (95% CI -136.82 to 26.82), standardized effect d = -0.15; z-test p = 0.188.
  • Arm C: mean 342.00 versus 312.00 on control; difference 30.00 (95% CI -55.50 to 115.50), standardized effect d = 0.08; z-test p = 0.492.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Arm B and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Arm C and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes describe fluid amounts before anesthesia and during the 30-minute post-anesthesia timeframe. Across the intervention comparisons, the pattern is not uniform: the pre-anesthesia amount differs more clearly for the echocardiography arm than for the Passive Leg Raising Test arm, while the post-anesthesia comparisons are less conclusive. The confidence intervals for post-anesthesia fluid amount include no mean difference for both intervention comparisons. These outcomes add context about fluid administration but do not directly measure the primary event.

The secondary findings can be considered alongside the primary hypotension results, but they should not be treated as an explanation for them. Fluid amount and hypotension are different outcomes, and the record does not report an analysis linking individual fluid exposure to event risk or testing whether fluid amount mediated an intervention effect. The information therefore does not establish that a difference in fluid amount caused, prevented, or accounted for a difference in hypotension.

The secondary results also carry less inferential weight because they are unadjusted and the registry does not report a multiplicity plan. When several outcomes and contrasts are examined, the chance of finding an apparently notable result by chance can increase. A prespecified testing hierarchy or adjustment can help address that issue, but the relevant plan is not reported in the registry record. The listed p-values should consequently be read as unadjusted comparisons, not as a set of confirmatory tests.

These outcomes are informative as descriptive evidence about the trial’s fluid measures, but their interpretation is limited by the absence of reported analysis details and by the distinction between fluid administration and the primary clinical event. They neither overturn the uncertain primary comparisons nor establish a mechanism for them.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Pre-anesthesia Fluid Amount
• Post-anesthesia Fluid Amount

9. Statistical Interpretation

10. Statistical Methods Explained

The posted primary outcome is binary: each participant is counted as having or not having the defined hypotension event during the 30-minute timeframe. For a binary outcome, a group risk is the proportion of participants in that group who experienced the event. The registry gives event counts and arm sizes, and the posted comparisons express the contrast as a risk difference. A risk difference is an absolute comparison between the two group risks. A negative value means the estimated event risk is lower in the intervention arm than in standard practice; it does not by itself establish that the intervention caused the difference.

What does the confidence interval describe?

A confidence interval describes the uncertainty around an estimated contrast under the statistical method used. For the primary contrasts, both intervals include zero, the value corresponding to no risk difference. This means the posted estimates are compatible with no difference as well as with effects in either direction within the interval. It does not mean that all values in the interval are equally plausible, and it does not give the probability that the true effect lies inside that particular interval.

The registry also includes relative measures for the primary comparisons, expressed as risk ratios and odds ratios. A risk ratio compares the risks in two groups as a relative quantity; an odds ratio compares the odds. These measures answer a different question from the risk difference, which expresses an absolute contrast. The relative intervals for both comparisons include the no-association value of one. When interpreting any one measure, its scale and the uncertainty around it should be kept in view. No adjustment for covariates is reported.

How should the p-values be read?

A p-value summarizes how inconsistent the observed data are with a specified null model, conditional on the assumptions of the test. It is not the probability that the null hypothesis is true, nor does it measure clinical importance. The posted primary p-values are 0.066 for echocardiography versus standard practice and 0.766 for the Passive Leg Raising Test versus standard practice. These are unadjusted values. The registry does not describe the test method or a prespecified analysis plan, so the p-values should not be treated as a complete account of the trial’s analysis.

The continuous secondary outcomes are reported as means and standard deviations. A mean difference compares the group averages, while the standard deviation describes the spread of observations within a group. A confidence interval around a mean difference indicates uncertainty in the estimated contrast. A wide interval can include both no difference and potentially meaningful differences in either direction. Fluid amount may vary substantially between participants, and the reported standard deviations convey that variability. The registry does not report distributional checks, transformations, or adjusted models.

What does unadjusted mean?

An unadjusted contrast compares the groups without accounting for other variables in the estimate. Randomization is intended to make groups comparable on average, but an unadjusted calculation from summary data cannot show how a prespecified model would handle baseline characteristics, missing outcomes, or other analysis choices. The posted comparisons therefore offer a straightforward descriptive contrast, not a substitute for a fully documented trial analysis. The registry reports no formal analyses, and its analysis plan is not reported in the registry record.

The recorded primary counts and secondary means are also limited to the information presented in the record. Without participant-level data, it is not possible to inspect the distribution of outcomes, verify the event classifications, assess the effect of missingness, or fit alternative models. These limits apply to the numerical summaries even when the calculations are internally consistent. The record marks discrepancy as false, but that does not supply a missing analysis plan or confirm unreported analytic choices.

Why can over-dispersion matter generally?

As a general statistical point, over-dispersion occurs when variability in the data is greater than a model assumes. If a model understates variability, uncertainty intervals may be too narrow and tests may appear more decisive than warranted. This is a general consideration for count or clustered outcomes; the primary outcome in this trial is posted as participant event counts, and the registry does not report a model assessing over-dispersion. It should not be assumed that such a problem occurred.

These methods concepts help separate the estimate, its uncertainty, and the assumptions behind an analysis. The registry record provides arm-level summaries and simple unadjusted contrasts, but it does not report enough methodological detail to establish every analytic choice. The appropriate reading is therefore descriptive and cautious: consider the direction and scale of the estimates, the intervals, and the limitations of the reported analysis rather than relying on a single p-value.

11. Confidence Intervals and Precision

Precision concerns how narrowly the data constrain an estimated effect. For the primary outcome, the echocardiography comparison has a risk-difference interval from -0.222 to 0.006. The interval includes zero and permits estimates on either side of no difference, though its limits are not symmetric around zero. The Passive Leg Raising Test comparison has an interval from -0.130 to 0.096, also spanning zero and allowing effects in either direction. These intervals do not support a precise conclusion that the true contrast is exactly zero.

The continuous outcome intervals likewise show different degrees of uncertainty. For pre-anesthesia fluid amount, the mean-difference interval for echocardiography versus standard practice is 137.2 to 252.8 ml, while the Passive Leg Raising Test comparison ranges from -16.91 to 70.91 ml. For post-anesthesia fluid amount, the intervals range from -136.8 to 26.82 ml for echocardiography and from -55.5 to 115.5 ml for the Passive Leg Raising Test. Intervals that include zero are compatible with no mean difference as well as with differences in either direction.

A confidence interval is not a guarantee about the true effect, and its width does not describe clinical importance on its own. The registry does not report the confidence-interval method or an adjusted analysis. These are unadjusted comparisons derived from the posted summaries. The precision should therefore be judged alongside the design and reporting limitations, not as a standalone measure of evidential strength.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not totals across arms or total events. They illustrate the number of participants per arm for 80% power and the number of participants per arm for 90% power under the stated planning setup. In plain terms, power is the chance that a study would detect an effect of the specified size if that effect were present and the assumptions held. The 90% power column uses a more demanding detection target than the 80% power column and therefore gives larger planning numbers for a given effect.

The listed illustration uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It bases the effect to detect on the stated fraction of the observed effect. The rows for 100%, 75%, and 50% of the observed effect show how the planning target changes as the assumed effect becomes smaller. Smaller effects need more participants to detect under the same assumptions. For example, the primary comparison of echocardiography with standard practice lists 324 participants per arm for 80% power when planning for 100% of the observed effect, and 582 participants per arm when planning for 75% of the observed effect.

These figures are planning illustrations derived from the observed effects, not the trial’s original design justification. The original sample-size assumptions are not reported in the registry record. This is not observed power: it does not measure the probability that the completed trial detected a true effect, and it does not resolve uncertainty in the observed estimates. The planning values depend on the stated assumptions and should not be read as a post hoc verdict on the trial.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.456; treatment proportion p₁ = 0.348; average p̄ = 0.402.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6935 = 1.3593.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6893 = 0.5801.
4. n = (1.3593 + 0.5801)² / (-0.1079)² = 323.1, rounded up to 324 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.456375838926175                          # control proportion
p1 <- 0.348484848484849                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(2070276)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 324 (80% power), 433 (90% power)
 75% of observed effect: n per arm = 582 (80% power), 778 (90% power)
 50% of observed effect: n per arm = 1,321 (80% power), 1,768 (90% power)
power.prop.test: 323.1 
Simulated power at n = 324 per arm: 0.802 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The record lists a primary outcome and two secondary outcomes, but does not report a statistical analysis plan describing how the outcome family was handled. No multiplicity adjustment or hierarchy for testing outcomes is reported in the registry record. The posted p-values are unadjusted. When several hypotheses are tested, the chance of at least one apparently unusual result can rise; this is a general statistical concern, not evidence that a particular finding in this trial is false. Without a reported plan, the secondary comparisons are best treated as exploratory or descriptive rather than as independently confirmatory.

The registry lists no reported analyses. It does not specify whether the primary analysis followed intention-to-treat, per-protocol, or another population definition. The numbers included in the arm summaries are available, but the record does not explain how those analysis sets were determined or whether exclusions occurred after randomization. No account of missing outcome data, imputation, or sensitivity analyses is reported in the registry record. These omissions matter because missingness or exclusions can affect the comparability created by randomization.

The outcome description gives a clinical definition of hypotension, but procedures for outcome assessment, adjudication, and handling of participants with incomplete measurements are not reported in the registry record. The listed single masking does not identify who was masked, and blinding of outcome assessment is not described. Details of the randomization sequence and allocation concealment are also not reported. These are reporting gaps; they do not establish that any specific procedure was absent.

The registry record does not report interim analyses, stopping rules, covariate adjustment, or a detailed statistical analysis plan. It is therefore not possible to determine from the record whether the posted contrasts were specified before results were observed or whether other analyses were undertaken. These uncertainties qualify the inferential interpretation, especially for secondary findings, without changing the numerical summaries that are posted.

15. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The serious adverse event figures report zero participants with a serious event in each of the three arms, and zero deaths in each arm. For other adverse events, the registry records one affected participant in Standard Clinical Practice and zero in each intervention arm. The record does not provide a list of serious adverse event terms, and the serious-event terms field is empty.

These are counts from the registry record, not evidence that no unrecorded events occurred. The record does not provide event definitions, severity details, timing, relatedness assessments, or a narrative of how adverse events were collected. It also does not describe whether adverse-event monitoring differed between arms. The small number of recorded other events should not be taken as a precise estimate of comparative safety, and the zero serious-event counts do not establish that serious events are impossible or that the arms are equivalent in safety.

Safety interpretation is therefore limited to the reported counts and the level of detail recorded. The registry does not report enough information to assess event types, context, or comparative risk with precision.

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

The posted primary results show that the estimated risk difference favored fewer hypotension events in the echocardiography arm compared with standard practice, while the estimate for the Passive Leg Raising Test was closer to no difference. However, both primary confidence intervals include no difference, and neither unadjusted comparison establishes a definitive effect. The data do not demonstrate equivalence: a non-significant result is not proof that the strategies and standard practice have the same outcome.

The results also do not establish that either strategy prevents hypotension, or that either is ineffective. The estimates are uncertain, and the registry does not report a formal analysis plan, adjustment strategy, or analysis population. The trial’s randomized design is relevant to interpreting comparisons, but the available record does not document enough detail to assess all features that affect the strength of causal conclusions.

The fluid outcomes describe measured amounts in the study arms, not a direct test of whether any amount is optimal or whether fluid exposure explains the primary endpoint. They should not be interpreted as evidence of a mechanism without an analysis relating fluid amounts to hypotension outcomes. Similarly, the safety counts are limited summaries and do not establish comparative safety.

The scope of the evidence is the recorded population undergoing spinal anesthesia, the specific strategies described, the defined systemic hypotension outcome, and the 30-minute timeframe. The registry does not provide detailed participant characteristics or broader follow-up results. Conclusions should not be extended to other populations, procedures, outcomes, or time periods based on these data alone. The record supports a cautious description of the observed group summaries and their uncertainty, rather than a clinical recommendation.

17. Why This Trial Matters Statistically

This trial raises a useful statistical question about how an intervention intended to guide fluid administration should be evaluated. The primary endpoint is a defined event, while the secondary endpoints measure fluid amounts. Keeping those outcomes separate is important: an intervention can alter a process measure without producing a clearly established difference in a clinical event, and a process measure alone cannot explain the event outcome.

The results also illustrate why an effect estimate should be read with its confidence interval rather than by its p-value alone. The primary comparisons point in different degrees and directions, but both intervals include no difference. This makes it inappropriate to reduce the findings to a simple yes-or-no conclusion. The width and span of the intervals show that the estimates remain compatible with more than one interpretation.

The planning illustrations reinforce a related principle: detecting smaller effects generally requires more participants under the same assumptions. Since those illustrations are based on observed effects and are not the trial’s original design justification, they do not reveal what effect the investigators planned to detect or whether the original design had adequate precision for that target. The original assumptions are not reported in the registry record.

Finally, the record highlights the importance of reporting an analysis plan, analysis populations, missing-data handling, and multiplicity decisions. Those details help readers distinguish prespecified confirmatory findings from exploratory comparisons and understand how uncertainty was quantified. Their absence does not invalidate the arm-level summaries, but it limits how confidently the posted comparisons can be interpreted.

18. 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.

Several limitations are specific to the information recorded for this trial. The registry provides brief arm descriptions, with portions of the descriptions truncated in the record. It does not give a full account of intervention procedures, adherence, or how decisions about fluid administration were made after the assessments. Consequently, the intervention contrast is defined at a broad level rather than through a complete reproducible protocol.

The primary hypotension definition includes several possible criteria, but the record does not break the event counts down by criterion. It also does not report the timing, duration, or severity of individual events, or how symptomatic hypotension was assessed. This prevents evaluation of which components of the composite definition contributed to the group results.

Important design and analysis details are not reported in the registry record, including the randomization method, allocation concealment, who was masked, the original sample-size justification, and the statistical analysis plan. The record does not state the analysis population, missing-data handling, or whether covariates were adjusted for. It also lists no formal analyses. These gaps limit assessment of risks of bias and the relationship between the posted calculations and any prespecified analysis.

Follow-up is reported for the primary outcome at 30 minutes and for the listed fluid outcomes at their specified timeframes. The registry does not report longer-term clinical outcomes. Participant characteristics and detailed baseline balance are also not included in the presented details, so the applicability of the findings to other clinical settings cannot be assessed from this record alone. The safety information is sparse, with no serious event terms or detailed adverse-event descriptions reported.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Predict Fluid Responsiveness in Spinal Anesthesia — NCT02070276.
• Registry record last updated 2020-07-13; status last verified 2020-07.
• Results first posted 2019-12-19.
• 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.

22. Record Summary

The registry record describes a completed randomized, single-masked, parallel-group trial with enrollment of 429. It compares Standard Clinical Practice with trans-thoracic echocardiography and the Passive Leg Raising Test for guiding preventive fluid administration before spinal anesthesia. The primary outcome is participants with systemic hypotension during 30 minutes, defined using blood-pressure thresholds or listed symptoms.

The posted primary comparisons are unadjusted and have confidence intervals that include no difference. The registry also reports pre-anesthesia and post-anesthesia fluid amounts as secondary outcomes. It lists zero serious adverse events and zero deaths in each arm, with one other adverse event recorded in the standard-practice arm.

The registry record does not report formal analyses, an analysis plan, multiplicity handling, missing-data methods, or the original sample-size justification. Those omissions limit interpretation beyond the posted summaries and their uncertainty.