Combined Spinal/Epidural (CSE) Saline Duration/Spread: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Combined Spinal/Epidural (CSE) Saline Duration/Spread (NCT01062893), a randomized phase 2 study. The primary outcome is Highest Sensory Blockade Level to Pinprick and to Cold.

2. Clinical Question

The registry describes an investigation of whether injecting saline into the epidural space during a combined spinal/epidural procedure changes the spread of spinal analgesia or anesthesia. The primary endpoint is the highest sensory level reached, assessed using pinprick and cold. The scale runs from T1, assigned level 17, to L5, assigned level 1. The posted primary comparison concerns the mean score in the two randomized groups.

The registry also identifies duration and onset of analgesia and time to highest sensory block as secondary outcomes. Other listed secondary outcomes concern fetal bradycardia, maternal hypotension, vasopressor use, itching, and post-dural-puncture headache. The registry describes the participants as being followed from placement of the combined spinal/epidural until they request additional pain medication as the spinal dose wears off. Further details about the study population, such as age or other eligibility characteristics, are not reported in the registry record.

3. Trial Design

This was a randomized, double-masked, parallel-group Phase 2 trial sponsored by Wake Forest University Health Sciences. The registry records an enrollment of 82 and a terminated study status. The study started in 2009-08, and primary completion was recorded in 2012-09. The reason for termination is not reported in the registry record.

The two groups differed by whether sterile normal saline was injected epidurally: one received 15 mls and the comparator received no saline. The registry labels both interventions as “OTHER.” It does not describe what masking meant in practice, who was masked, or how randomization was generated or concealed. These details are not reported in the registry record.

The primary outcome is the highest sensory blockade level to pinprick and cold, measured up to 20 minutes. The registry reports a mean and standard deviation for each group. It also lists secondary outcomes, including analgesia duration, onset, time to highest sensory block, and several maternal or fetal events. The registry records 11 outcome measures and 10 posted secondary outcomes, while numerical results are available for three secondary measures.

For the primary outcome, posted group summaries include 27 participants in the no-saline group and 28 in the saline group. Those outcome counts do not account for the full recorded enrollment. Reasons for the difference, participant disposition, and the analysis population definition are not reported in the registry record. No original statistical plan or sample-size justification is reported there, so the posted results cannot establish which analyses were planned in advance.

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

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 Highest Sensory Blockade Level to Pinprick and to Cold, measured over up to 20 minutes.

The primary endpoint is the highest sensory blockade level reached to pinprick and to cold, measured up to 20 minutes. It describes the uppermost recorded extent of sensory block during the stated observation period. The registry assigns level 17 to T1, the highest point on the stated scale, and level 1 to L5, the lowest. A group mean therefore summarizes the recorded scale values across participants; the standard deviation describes variation among those values.

Sensory spread is relevant to the trial’s stated question because the study investigates whether epidural saline changes the spread of subsequent spinal analgesia or anesthesia. Measuring the highest level to both pinprick and cold gives sensory assessments within that question. The registry does not clarify whether the posted primary result combines the two assessments into one measure or reports a particular method of combining them. That detail is not reported in the registry record.

The outcome is a scale-based continuous measure in the registry, rather than a direct measure of pain relief or duration. It should be interpreted as a comparison of recorded mean sensory levels, not as a direct estimate of how much pain relief participants experienced. The registry describes the endpoint timeframe as up to 20 minutes and does not report further detail about the measurement schedule or how missing observations were handled.

7. Results Posted in the Registry

• 15 Mls Saline: mean 11.60 versus 10.10 on control; difference 1.50 (95% CI 0.20 to 2.80), standardized effect d = 0.61; z-test p = 0.024.

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.

Duration of Analgesia (Time to Request Additional Analgesia)

• 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:
  • 15 Mls Saline: mean 77.30 versus 57.20 on control; difference 20.10 (95% CI 3.16 to 37.04), standardized effect d = 0.63; z-test p = 0.020.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for 15 Mls Saline than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Onset of Analgesia

• 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:
  • 15 Mls Saline: mean 6.07 versus 7.96 on control; difference -1.89 (95% CI -4.19 to 0.41), standardized effect d = -0.44; z-test p = 0.107.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between 15 Mls Saline and the control. The interval gives the range of effects that remain compatible with the data.

Time to Highest Sensory Block

• 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:
  • 15 Mls Saline: mean 13.57 versus 12.96 on control; difference 0.61 (95% CI -3.46 to 4.68), standardized effect d = 0.08; z-test p = 0.769.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between 15 Mls Saline and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes provide related but distinct views of the labor analgesia process. The posted continuous measures concern how long analgesia lasted, how quickly it began, and when the highest sensory block was reached. Their pattern is not uniformly in one direction: duration has a positive mean difference for saline relative to no saline, onset has a negative mean difference, and time to highest block has a small positive estimate. The intervals and unadjusted p-values vary, so the secondary results do not form a single consistent statistical pattern.

These outcomes can add context to the primary sensory-level comparison, but they do not measure the same thing. The primary endpoint records the highest sensory level to pinprick and cold; the secondary timing measures record minutes to specified events. A difference in one measure does not automatically imply a corresponding difference in another. The registry does not report a model linking the timing outcomes to the primary sensory measure.

The registry lists 10 secondary outcomes, including event outcomes relating to maternal and fetal safety, but numerical continuous-outcome results are posted for three. The absence of a numerical result for the other listed secondary outcomes should not be interpreted as showing no event or no difference. Results for those outcomes are not reported in the registry record as endpoint-specific comparisons.

Unadjusted secondary results carry less weight because multiple outcomes create multiple opportunities for apparently notable results, even when no single outcome has a clear underlying difference. General statistical practice treats secondary analyses as supportive unless their priority and multiplicity handling are specified. The registry does not report a testing hierarchy or multiplicity adjustment. These results are therefore best read as exploratory context, not as independent confirmation of the primary comparison. The registry also does not report whether the three numerical secondary analyses were prespecified.

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

• Duration of Analgesia (Time to Request Additional Analgesia)
• Onset of Analgesia
• Time to Highest Sensory Block
• Number of Participants Who Had Occurrence of Fetal Bradycardia
• Number of Participants Who Had Occurrence of Maternal Hypotension
• Occurrence of Use of Vasopressors
• Number of Participants Who Had Occurrence of Itching
• Number of Participants Who Had Occurrence of Post Dural Puncture Headache

9. Statistical Interpretation

10. Statistical Methods Explained

What does the mean summarize?

The primary measure is recorded on a scale with levels from L5 at level 1 to T1 at level 17. The posted group means are 10.1 for no saline and 11.6 for 15 mls saline. A mean compresses the individual recorded values into a group summary. It is useful for comparing groups on a continuous measure, but it does not show the full distribution or whether participants had similar values. The standard deviations, 2.9 and 1.9 respectively, describe the amount of spread around each group mean. They are measures of participant-to-participant variation, not confidence intervals around the means.

What does the mean difference represent?

The posted comparison expresses the saline-group mean relative to the no-saline-group mean. Its estimate is 1.5 scale units. A positive estimate means the saline group has the higher recorded mean on this scale. Because the scale assigns higher values to levels closer to T1, the direction can be interpreted using that scale definition. The estimate is an average contrast; it does not imply that every participant had a higher sensory level, nor does it describe individual responses.

What does the confidence interval add?

A confidence interval describes uncertainty around an estimated difference under the statistical method and assumptions used. The primary interval runs from 0.199 to 2.801. It gives a range of values reasonably compatible with the posted estimate under that framework. The interval does not mean that the true value has a 95% probability of lying in this particular range. It also does not account for all possible sources of uncertainty, such as unreported outcome handling or analysis choices. The registry does not report the method used to form the interval.

How should the p-value be read?

The primary unadjusted p-value is 0.024. In general, a p-value describes how unusual data at least as inconsistent with a specified null hypothesis would be if that hypothesis and the statistical model held. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. The registry does not report whether the comparison was prespecified, which test was used, or whether the p-value accounts for any multiplicity.

What is the role of standard deviation?

Standard deviation describes the observed variation within a group, while the standard error describes uncertainty in an estimate such as a mean. The posted results include standard deviations for the group summaries and separate standard errors in the comparison data. These quantities answer different questions. In general, a larger standard deviation indicates more variation among participant measurements; it does not by itself determine whether a difference between group means is precise. Precision also depends on the number of observations and the comparison method.

What can the secondary comparisons establish?

The secondary outcomes are continuous measures of time, and the registry posts group means, standard deviations, mean differences, confidence intervals, and unadjusted p-values for duration of analgesia, onset of analgesia, and time to highest sensory block. The reported mean difference is a contrast in minutes for these outcomes. Each estimate describes that outcome as recorded; it does not substitute for the primary sensory-level measure. The registry does not report whether these secondary analyses were prespecified or whether their inferential results were adjusted for multiple comparisons.

Which analysis details are unavailable?

The registry does not report a detailed statistical analysis plan, the original sample-size justification, the specific tests used, covariate adjustment, missing-data methods, or the analysis population definition. These details matter because they establish how endpoints were selected, how observations were included, and how uncertainty was calculated. The posted statistics can be read as descriptive summaries and group comparisons, but unreported methods should not be inferred from the numerical values alone.

In general, randomization is intended to support a fair comparison by assigning participants to groups without choosing the group based on their characteristics. Double masking is intended to limit some influences on treatment administration or outcome assessment. The registry records randomized allocation and double masking, but does not explain the implementation. It is therefore possible to describe the design labels, but not to assess from the registry record how well those procedures were carried out.

11. Confidence Intervals and Precision

The primary mean difference is 1.5 scale units, with a 95% confidence interval from 0.199 to 2.801. The interval excludes zero and spans values from a comparatively small positive difference to a larger positive difference. This conveys both the direction of the posted estimate and the uncertainty around its magnitude. The registry does not report the interval method, and the interval does not address potential bias from missing outcome data, selective reporting, or analysis decisions that are not described.

The group summaries are based on 27 participants without saline and 28 participants receiving 15 mls saline. Standard deviations are 2.9 and 1.9. The difference in those standard deviations indicates that the observed spread was not identical between groups, although the registry does not give individual-level data to examine the distributions. A mean and standard deviation alone cannot show whether the measurements were symmetric, whether there were outliers, or whether subgroup patterns differed.

The secondary confidence intervals vary in width and in whether they include zero. For duration of analgesia, the interval is 3.159 to 37.04 minutes. For onset of analgesia, it is -4.185 to 0.405 minutes. For time to highest sensory block, it is -3.457 to 4.677 minutes. These intervals communicate uncertainty for those specific mean differences, but the registry does not report multiplicity adjustment. They should therefore be interpreted as unadjusted comparisons rather than as a family of jointly controlled conclusions.

Precision is not the same as importance. A confidence interval describes statistical uncertainty in an estimate under a method; it does not define a clinically meaningful range. The registry does not report a threshold for a meaningful sensory-level difference or a prespecified margin for interpreting the endpoint. The posted results consequently describe the estimated differences and their statistical precision, but do not settle whether their magnitude is meaningful for a clinical decision.

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 illustrations based on the observed effect, not the trial’s original design justification. For these continuous outcomes, the displayed participant counts are per arm, not total participants or total events. The assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each planning scenario uses the stated fraction of the observed effect as the effect to detect. The trial’s own original sample-size assumptions are not reported in the registry record.

The 80% power column describes the number of participants per arm in a hypothetical study designed to have an 80% chance of detecting the specified effect under the stated assumptions, if that effect is real and the model assumptions hold. The 90% power column gives the corresponding planning count for a 90% chance. These are planning targets, not evidence about the probability that the completed trial found a true effect.

Rows planning for 100% of the observed effect use the full estimated difference as the target. Rows planning for 75% or 50% of the observed effect represent smaller target differences. Smaller effects are harder to distinguish from random variation, so they require more participants under the same planning assumptions. The counts are illustrations anchored to the observed effect in this trial; the observed estimate itself is uncertain and may not be the effect a future study would encounter.

These figures are not observed power. They do not describe what the completed study was capable of establishing after its results were known. They are conditional planning calculations using specified assumptions, and the registry does not report that these assumptions were used when the trial was designed.

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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 1.500; pooled standard deviation σ = 2.442.
2. n = 2 × (1.96 + 0.842)² × 2.442² / 1.500² = 41.6, rounded up to 42 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
delta <- 1.5                      # observed difference in means
sigma <- 2.44227700745269                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^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 (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1062893)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 42 (80% power), 56 (90% power)
 75% of observed effect: n per arm = 74 (80% power), 100 (90% power)
 50% of observed effect: n per arm = 167 (80% power), 223 (90% power)
power.t.test: 42.6 
Simulated power at n = 42 per arm: 0.793 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-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 registry identifies a primary endpoint and multiple secondary outcomes. Testing many outcomes can increase the chance that one or more comparisons appear statistically notable by chance. In general, multiplicity methods control or account for that family of tests, or a prespecified hierarchy can distinguish confirmatory from exploratory outcomes. The registry does not report a multiplicity adjustment, a testing hierarchy, or a detailed statistical analysis plan. The posted secondary p-values are unadjusted, so they should not be treated as if they arose from a single isolated test.

The primary comparison also has an unadjusted p-value. The registry does not report whether the primary endpoint was the sole confirmatory test, whether there were planned interim analyses, or whether the analysis was changed after data collection. Those items are not reported in the registry record; no assumptions about them can be made from the posted statistics.

Missing-data handling is another important unknown. The primary outcome summaries include 27 participants in the no-saline group and 28 in the saline group, whereas enrollment is recorded as 82. The registry does not report participant flow, the reasons for the difference in outcome counts, the number with missing measurements, or any imputation or sensitivity method. The reported results therefore describe the participants represented in the posted outcome summaries, and their relationship to all enrolled participants cannot be determined from the registry record.

The analysis population is not reported in the registry record. It is not stated whether the analysis followed randomized assignment regardless of treatment received, included only participants with measured outcomes, or used another rule. The registry also does not report adjustments for baseline characteristics or the handling of protocol deviations. These omissions limit evaluation of how the group comparison was constructed and whether the analysis preserved the original randomized comparison.

The registry has no reported analyses listed, despite posting outcome summaries and comparison statistics. This means that analysis details such as the inferential test, model specification, and prespecification cannot be confirmed from the registry record. The numerical results remain interpretable as posted summaries, but methodological uncertainties should be kept separate from the estimates themselves.

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.

The registry reports serious adverse events for 27 participants at risk in the no-saline group and 28 participants at risk in the 15 mls saline group. It records zero serious adverse events in each group. It also records zero other adverse events in each group and zero deaths in either group. These are counts for the participants identified as at risk in the safety record, not necessarily all enrolled participants.

Zero recorded events means that the registry reports none in those groups during the recorded safety assessment. It does not establish that an event is impossible or that the groups have identical risk. With limited numbers at risk, uncommon events may not be observed, and the precision of event-rate comparisons cannot be evaluated without further information. The registry does not provide event-specific timing, severity details, or a statistical comparison of safety outcomes. The listed maternal and fetal secondary outcomes should not be inferred to have zero occurrences solely from the aggregate adverse-event counts.

Safety counts are separate from the continuous efficacy outcomes and should be read as descriptive registry entries. The record lists no serious adverse-event terms. Further detail about safety monitoring and the duration of adverse-event follow-up is not reported in the registry record.

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

The posted primary result is a comparison of average sensory-block level between the randomized saline and no-saline groups. The mean was 11.6 in the 15 mls saline group and 10.1 in the no-saline group, with a mean difference of 1.5 scale units and a 95% confidence interval from 0.199 to 2.801. The direction of that difference is interpretable using the registry’s scale, where higher values correspond to levels closer to T1. These figures describe the recorded sample and the stated endpoint.

That comparison does not establish how each participant responded, whether the difference was important to patients, or whether the result would be similar in another population. The registry does not report a threshold for clinical importance, additional population details, or the analysis methods needed to assess all sources of uncertainty. It also does not report why the study was terminated. The posted result should not be extended beyond the endpoint, participants, and time frame recorded.

The secondary results concern timing outcomes and have different estimates and levels of statistical uncertainty. They do not provide a single, uniform account of the intervention’s effects, and unadjusted secondary comparisons warrant caution when multiple outcomes are considered. The registry lists other outcomes for which numerical endpoint-specific results are not reported in the registry record.

The safety record reports zero serious adverse events, zero other adverse events, and zero deaths in the recorded groups. Those counts do not demonstrate the absence of risk, particularly when the numbers at risk are limited and event-specific precision is not provided. Overall, the registry supports a description of the posted statistical results, not a broad conclusion about benefit, lack of benefit, or safety.

17. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between the target of a study and the quantity actually measured. The stated clinical motivation concerns pain relief and duration of labor analgesia, while the primary posted endpoint is highest sensory blockade level to pinprick and cold. The secondary outcomes include duration and onset, but the registry does not report a formal model connecting those timing measures to the primary sensory measure. Interpreting each endpoint according to what it measures prevents a sensory-level difference from being treated as a direct measurement of pain relief.

The record also illustrates why an effect estimate should be read alongside its uncertainty. The primary mean difference is accompanied by a confidence interval, giving more information than a p-value alone. At the same time, the difference between enrollment and the primary outcome counts raises questions about participant disposition and analysis populations that cannot be answered from the registry record. Statistical precision within the posted comparison does not remove uncertainty about who is represented or how missing outcomes were handled.

Secondary outcomes and safety counts add context but have limits. Several outcomes are listed, only some have numerical continuous results, and multiplicity handling is not reported. The safety record has no recorded events in the analyzed risk groups, but limited observed counts cannot characterize uncommon events precisely. Together, these points show why endpoint definitions, participant flow, analysis plans, and complete outcome reporting matter alongside numerical estimates.

For clinical researchers and biostatisticians, the record is a reminder to separate descriptive findings from conclusions about clinical importance. A registry can support careful reading of group means, differences, and uncertainty while leaving key design and analysis details unresolved. Transparent reporting of those details would make it easier to assess the robustness and scope of the comparison.

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 status is terminated, but the reason for termination is not reported in the registry record. Enrollment is 82, while the primary outcome summaries include 27 participants in one group and 28 in the other. Participant flow and the reasons for those outcome counts are not reported, so the extent and possible consequences of missing outcome data cannot be assessed.

The registry does not report detailed eligibility criteria or participant characteristics. It also does not describe the randomization procedure, allocation concealment, masking implementation, or analysis population. Although the design is labeled randomized and double-masked, those labels alone do not provide enough detail to evaluate execution.

The outcome record identifies 10 posted secondary outcomes, but numerical results are available for three continuous secondary measures. Endpoint-specific numerical results for the remaining listed outcomes are not reported in the registry record. The registry also does not report whether secondary outcomes were prespecified, how multiplicity was handled, or whether any results were omitted.

The primary outcome is reported as a mean and standard deviation on a level scale. The record does not clarify how pinprick and cold assessments were combined, how measurements were scheduled within the stated timeframe, or how missing measurements were handled. The analysis plan, statistical tests, original sample-size justification, and any interim analyses are not reported in the registry record. These limitations constrain interpretation of the posted estimates without changing what those estimates numerically report.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Combined Spinal/Epidural (CSE) Saline Duration/Spread — NCT01062893.
• Registry record last updated 2018-10-16; status last verified 2018-10.
• Results first posted 2018-10-16.
• 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

NCT01062893, titled “Combined Spinal/Epidural (CSE) Saline Duration/Spread,” is a Phase 2 randomized, double-masked, parallel-group trial of epidural saline during combined spinal/epidural treatment for labor pain. The registry records enrollment of 82, a terminated status, a start date of 2009-08, and primary completion in 2012-09.

The primary endpoint is highest sensory blockade level to pinprick and cold, measured up to 20 minutes. The posted mean difference for 15 mls saline versus no saline is 1.5 scale units, with a 95% confidence interval from 0.199 to 2.801 and an unadjusted p-value of 0.024. Numerical secondary results are posted for duration of analgesia, onset of analgesia, and time to highest sensory block. The registry reports zero serious adverse events, zero other adverse events, and zero deaths in the recorded groups. Details about the original analysis plan, participant flow, and reason for termination are not reported in the registry record.