Nitroglycerin Infusion During Cardiac Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nitroglycerin Infusion During Cardiac Surgery (NCT01901419), a randomized na study. The primary outcome is Plasma Lactate Level, Before Incision.

2. Clinical Question

3. Trial Design

The registry describes a randomized, double-masked, parallel-group trial sponsored by Tri-Service General Hospital (TSGH). The record lists the study as completed, with enrollment of 80. The listed study start is 2013-07-08 and primary completion is 2017-06-08. The phase is listed as NA. The primary outcome summaries include 32 participants in the high-dose arm and 31 in the low-dose arm; the record does not explain the relation between these outcome counts and the enrollment figure or describe participant flow.

The trial compared high-dose nitroglycerin infusion, 1-5 mcg/kg/min, with low-dose nitroglycerin infusion, 0-0.1 mcg/kg/min. The registry labels masking as double but does not identify which people were masked or describe the masking procedure. It also does not report the randomization method or allocation concealment. Those details are not reported in the registry record.

The stated rationale concerns possible effects of nitroglycerin during rewarming on systemic ischemic stress and heparin neutralization. The primary outcome, however, is plasma lactate before incision. Secondary outcomes named in the record include activated coagulation time before cardiopulmonary bypass and after protamine administration, postoperative dopamine infusion, time to extubation, and length of ICU stay. Quantitative arm summaries are available in the record for the two activated coagulation time measures and postoperative dopamine infusion; numerical estimates for time to extubation and length of ICU stay are not reported in the registry record.

The registry does not report the original sample-size justification, the planned primary analysis details beyond the posted results, interim analyses, or a fuller analysis-population definition. It also does not report how missing outcome observations were handled.

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

Reasons for not completing this period:

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 Plasma Lactate Level, Before Incision, measured over Before Incision.

The primary outcome is plasma lactate level before incision, measured in mmol/L and summarized as a mean with a standard deviation for each arm. The registry lists the timeframe as before incision. In the posted summary, the high-dose arm has a mean of 1.1 and standard deviation of 0.5, and the low-dose arm has a mean of 1.0 and standard deviation of 0.4.

General: Lactate is used in clinical research as a marker relevant to metabolic stress and tissue perfusion. In this trial, that general role connects to the stated rationale about systemic ischemic stress. A single mean describes the group’s average measurement, while the standard deviation describes the spread of individual measurements around that average; it is not the uncertainty interval for the mean difference.

The timing matters for interpretation. The intervention is described as occurring during rewarming, whereas the primary endpoint is recorded before incision. On the registry wording alone, the primary measurement does not establish a change in lactate during rewarming or after the infusion. The record does not report a separate primary endpoint at a later time, repeated lactate measurements, or an explanation of how this timing was selected. Thus, the posted primary result addresses the between-arm comparison for the specified before-incision measurement, not every part of the proposed tissue-perfusion mechanism.

7. Results Posted in the Registry

• Low-dose NTG: mean 1.00 versus 1.10 on control; difference -0.10 (95% CI -0.32 to 0.12), standardized effect d = -0.22; z-test p = 0.380.

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.

Activated Coagulation Time, Before Start of CPB

• 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:
  • Low-dose NTG: mean 153.10 versus 158.90 on control; difference -5.80 (95% CI -15.16 to 3.56), standardized effect d = -0.31; z-test p = 0.225.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Low-dose NTG and the control. The interval gives the range of effects that remain compatible with the data.

Activated Coagulation Time, After Protamine Administration

• 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:
  • Low-dose NTG: mean 138.20 versus 144.20 on control; difference -6.00 (95% CI -13.70 to 1.70), standardized effect d = -0.38; z-test p = 0.127.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Low-dose NTG and the control. The interval gives the range of effects that remain compatible with the data.

Post-op Dopamine Infusion

• 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:
  • Low-dose NTG: mean 4.70 versus 3.70 on control; difference 1.00 (95% CI 0.06 to 1.94), standardized effect d = 0.53; z-test p = 0.037.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Low-dose NTG than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes cover coagulation measures around cardiopulmonary bypass and protamine administration, postoperative dopamine infusion, time to extubation, and length of ICU stay. Quantitative comparisons in the available outcome summaries cover the activated coagulation time measures and postoperative dopamine infusion. Numerical arm results for time to extubation and length of ICU stay are not reported in the registry record.

Across the available numerical secondary results, the two coagulation comparisons have recalculated confidence intervals that include zero. The postoperative dopamine comparison has a recalculated interval that excludes zero, and the registry’s reported p-value for that outcome is 0.046. These patterns do not alter the interpretation of the primary lactate result: they concern different outcomes and timepoints, and the primary endpoint remains the before-incision lactate measure. Nor do the secondary results resolve the timing mismatch between the intervention rationale and primary endpoint.

These outcomes can provide context about other aspects of the study, but they should not be treated as interchangeable measures of one underlying effect. A coagulation time, dopamine infusion, extubation timing, and ICU stay represent distinct outcomes. The registry does not report a combined secondary endpoint or a prespecified hierarchy among these measures.

The registry lists 30 outcome measures and 30 analyses. When many outcomes are examined, unadjusted secondary results carry less weight because the chance of an apparently noteworthy finding somewhere in the set can increase. The registry record does not report a multiplicity adjustment or describe which secondary comparisons were designated confirmatory. The postoperative dopamine result is therefore best regarded as a secondary signal requiring cautious interpretation, not as independent confirmation of the primary outcome or of the trial’s proposed mechanism.

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

• Activated Coagulation Time, Before Start of CPB
• Activated Coagulation Time, After Protamine Administration
• Post-op Dopamine Infusion
• Time to Extubation
• Length of ICU Stay

9. Statistical Interpretation

10. Statistical Methods Explained

The registry reports a randomized, double-masked, parallel-group design and a two-sided t-test for the primary comparison. The outcome is continuous, and the arm summaries are means and standard deviations. A t-test evaluates whether the observed difference in group means is sufficiently inconsistent with a null hypothesis of equal means under the test’s assumptions. A two-sided test allows evidence in either direction; it does not prespecify that only a higher or only a lower mean matters.

What does the mean difference represent?

The posted comparison is low-dose relative to high-dose. For the primary lactate measure, the recalculated mean difference is -0.1 mmol/L. The negative sign indicates that the low-dose arm’s reported mean is lower than the high-dose arm’s mean for this comparison order. This is a descriptive direction, not by itself a claim of a meaningful or reliable treatment effect. The magnitude needs to be read alongside the uncertainty interval and the amount of variation among participants.

What does a confidence interval add?

General: A confidence interval expresses the uncertainty around an estimated effect under the statistical model used to construct it. It is not a range containing a known proportion of individual participants’ values, and it is not a probability statement about the true effect after observing the data. In the primary comparison, the recalculated interval includes zero, so the summaries are compatible with no difference as well as with effects in either direction. The interval is more informative than a p-value alone because it conveys the range and direction of effects compatible with the estimate and its uncertainty.

How should the p-value be read?

General: A p-value is the probability, under the null hypothesis and the assumptions of the test, of data at least as inconsistent with that null as the observed data. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. The recalculated unadjusted p-value for the primary outcome is 0.38. The registry reports p = 0.618 for its two-sided t-test. The values should be understood as results from the summary-based recalculation and the registry’s own reported analysis, respectively, rather than as interchangeable numbers.

For the secondary comparisons, the recalculated estimates and p-values are also unadjusted. An unadjusted p-value evaluates an individual comparison without accounting for the fact that other outcomes or comparisons may also have been examined. When many hypotheses are considered, the chance of at least one apparently notable result can increase. No adjustment procedure is reported in the registry record, so the secondary p-values should not be interpreted as if they account for the full set of analyses.

What assumptions underlie the comparisons?

General: A standard two-sample t-test is typically based on independent observations, an appropriate continuous measurement, and a sampling distribution for the mean difference that is adequately approximated by the test’s model. The standard version also relies on a variance assumption; variants can address unequal variances. The registry names a two-sided t-test but does not report whether an equal-variance or unequal-variance version was used, or provide diagnostic checks. There is no basis in the record to infer which version or checks were applied.

Randomization is intended to support a fair comparison by making assignment unrelated to participant characteristics on average, but the registry does not detail the randomization procedure or report baseline balance beyond the posted outcome values. Double masking can reduce some forms of expectation or assessment bias, but the record does not say who was masked or how masking was maintained. These design labels are useful context, not a substitute for the missing operational details.

The primary summaries are based on 32 and 31 participants in the respective arms. The registry enrollment figure is 80, but participant flow and the reason for differences between enrollment and the outcome counts are not reported in the registry record. The analysis population, handling of incomplete observations, and any exclusions are also not reported. Consequently, the arm summaries cannot establish whether the analysis followed an intention-to-treat approach or another population definition.

The stated trial rationale involves potential effects on perfusion and coagulation, but the primary outcome is lactate before incision. This is important methodologically: the endpoint’s timing and construct determine what the statistical comparison can answer. A statistically precise estimate at one time point would still not directly estimate a change at another time point or establish a mechanism. The registry record does not report a repeated-measures model or a primary analysis based on later lactate values.

The study lists 30 outcome measures and 30 analyses. The record does not report a hierarchy for secondary outcomes, a prespecified multiplicity strategy, interim analyses, or the original sample-size rationale. Those omissions make it difficult to distinguish confirmatory from exploratory comparisons beyond the named primary outcome. Statistical significance for an isolated secondary result should therefore be read cautiously, alongside its estimate, interval, outcome status, and the broader multiplicity context.

11. Confidence Intervals and Precision

Precision concerns how tightly the data locate an effect estimate, not whether that estimate is clinically important. For the primary lactate comparison, the recalculated mean difference is -0.1 mmol/L, and the confidence interval extends across zero. This means that the available summary data do not pin down the direction of the underlying difference with confidence. The interval is not a declaration that the arms are equivalent, and its inclusion of zero is not proof that there is no difference.

The standard deviations are 0.5 mmol/L for high-dose and 0.4 mmol/L for low-dose, while the outcome counts are 32 and 31. These summaries describe dispersion and the amount of information contributing to the comparison. Standard deviations describe variability among observations; confidence intervals describe uncertainty in an estimated mean difference. Confusing the two can make an estimate appear more precise or less precise than it is.

General: A narrower confidence interval indicates greater precision, while a wider interval leaves more values compatible with the data and model. Precision is affected by the amount of information and variability, as well as by the analysis assumptions. The registry does not report a confidence level for its own primary analysis interval; the recalculation is an unadjusted summary-based estimate. It should not be conflated with a registry-reported interval, which is not listed for the reported t-test.

The secondary comparisons also have uncertainty intervals. Some include zero and one does not, but those intervals are unadjusted and arise among multiple outcomes. A narrow interval for one outcome would not resolve concerns about selective interpretation, endpoint timing, missing-data handling, or the study’s broader multiplicity. Precision is specific to the outcome and comparison; it does not automatically generalize to other measures or clinical consequences.

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 sample-size figures are planning illustrations based on the observed effect, not the trial’s original design assumptions. They use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each row asks how many participants per arm would be needed to detect the stated fraction of the observed effect under those assumptions. The primary-outcome rows are participant counts per arm, not total event counts.

The 80% power column describes a planning target that, under the stated assumptions and effect size, would give an 80% chance of a statistically significant result if that effect were the true effect. The 90% power column uses a higher chance target under the same type of assumptions. These are design calculations, not a description of what happened in this trial. For the primary outcome, the illustration lists 323 participants per arm for 80% power and 433 participants per arm for 90% power when planning for 100% of the observed effect. Planning for 75% of the observed effect gives 575 and 769 participants per arm, respectively; planning for 50% gives 1,292 and 1,730 participants per arm, respectively.

Smaller effects are harder to distinguish from random variation, so detecting a smaller fraction of the observed effect requires more participants per arm in these illustrations. The observed effect itself may be unstable, especially when estimated from a small study, so these figures should not be treated as definitive design recommendations. This is not observed power. The registry’s original sample-size justification and design assumptions are not reported in the registry record.

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 = -0.100; pooled standard deviation σ = 0.454.
2. n = 2 × (1.96 + 0.842)² × 0.454² / -0.100² = 323.0, rounded up to 323 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 <- -0.1                      # observed difference in means
sigma <- 0.453583184121758                     # 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(1901419)
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 = 323 (80% power), 433 (90% power)
 75% of observed effect: n per arm = 575 (80% power), 769 (90% power)
 50% of observed effect: n per arm = 1,292 (80% power), 1,730 (90% power)
power.t.test: 323.9 
Simulated power at n = 323 per arm: 0.800 (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. Analyses Reported by the Sponsor

The registry reports a two-sided t-test for the primary comparison and gives p = 0.618. A simple unadjusted recalculation from the posted arm means, standard deviations, and participant counts gives p = 0.38, with a mean difference of -0.1 mmol/L. These are the registry’s reported analysis and a separate summary-statistic recalculation, respectively. The recalculation is not a replacement for the registry’s analysis.

The registry record does not explain why the p-values differ. It does not report additional analysis details, participant-level data, or test implementation information that would allow the source of the difference to be identified. The reported analysis does not include an estimate or confidence interval in the available record. Accordingly, the p-values should not be combined or selectively treated as if they came from one calculation. The reported result and the recalculation should remain clearly distinguished, with the recalculated estimate interpreted as an approximate unadjusted check based on posted summaries.

For the secondary comparisons, the registry also reports two-sided t-test p-values, while the recalculated comparisons use posted summary statistics. Differences between reported and recalculated values are not explained in the registry record. The reported methods and results remain the trial record’s own account; summary-based recalculation can provide context but cannot recover analysis details that are not reported.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists 30 outcome measures and 30 analyses, while the record also names five secondary outcomes. It reports no multiplicity adjustment, testing hierarchy, or other strategy for controlling the interpretation of multiple comparisons. Without such information, the individual unadjusted p-values do not account for the number of outcomes examined. A result that appears notable in one secondary comparison may arise by chance when many comparisons are made.

The record does not report interim analyses, stopping rules, or whether the analysis plan was finalized before outcomes were examined. These details are not reported in the registry record, so no claim can be made about whether they were used. The original statistical analysis plan and the original sample-size justification are also not reported. This limits the ability to assess which choices were specified in advance and how the reported analyses relate to the trial’s intended confirmatory questions.

Missing-data handling is not described. The record does not report the amount or pattern of missingness for each endpoint, imputation procedures, or sensitivity analyses. Participant flow from the enrollment figure to the arm-specific outcome counts is also not reported. Without those details, it is not possible to determine whether the posted summaries include all randomized participants for each outcome or how incomplete measurements might affect the estimates.

The analysis population is not reported in detail. The registry does not state whether the analyses used all randomized participants, participants with available outcome data, or another defined population. It also does not describe exclusions after randomization. These omissions matter because the interpretation of a randomized comparison depends partly on how participants are retained and analyzed.

Finally, the primary endpoint is measured before incision, while the stated intervention is during rewarming. The registry does not report repeated lactate values or a primary endpoint analysis at the intervention period. This limits the scope of the primary result independently of multiplicity: even a clear comparison at the stated timepoint would not establish a later response without later measurements.

16. 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 serious adverse event terms

Serious events with the highest arm-level rate: pneumonia (3.2%), massive hemothorax (3.2%), re-sternotomy for bleeding (3.1%), mediastinitis with septic shock (3.1%).

The registry reports serious adverse events for 2 of 32 participants in the high-dose arm and 2 of 31 participants in the low-dose arm. It reports 0 other adverse events in each arm, and deaths of 1 in the high-dose arm and 0 in the low-dose arm. These figures describe the posted counts among participants listed at risk; they do not establish that an event was caused by the infusion or that the arms have equivalent safety.

The serious-event terms listed include pneumonia and massive hemothorax at 3.2% each, and re-sternotomy for bleeding and mediastinitis with septic shock at 3.1% each. The registry does not provide enough detail in these summaries to attribute each term to a particular arm or assess its relation to treatment. Event definitions, timing, severity grading, and attribution procedures are not reported in the registry record.

Safety counts from a trial of this size are descriptive and can be imprecise, especially for uncommon events. The absence of reported other adverse events is not proof that none occurred beyond the recorded categories, and the death counts alone do not establish cause. These figures should be read as registry-reported event summaries, not causal comparisons.

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

The primary posted data describe mean plasma lactate before incision in participants assigned to high-dose or low-dose nitroglycerin infusion. The recalculated mean difference is -0.1 mmol/L, and its confidence interval includes zero. This indicates uncertainty about the direction and magnitude of the between-arm difference for that measurement. It does not demonstrate equality, and it does not show that either infusion dose changes lactate.

The result is specific to the recorded endpoint and its timing. The trial rationale discusses nitroglycerin during rewarming, but the listed primary outcome is before incision. The registry record does not report a primary lactate measurement during or after rewarming, so the primary comparison cannot establish whether lactate changed in response to the intervention at the proposed time. It also cannot directly confirm or refute the proposed mechanisms involving tissue perfusion or heparin neutralization.

The registry includes secondary outcome results for selected coagulation measures and postoperative dopamine infusion. These outcomes offer additional descriptive information, but they do not replace the primary comparison. The postoperative dopamine result is one unadjusted secondary comparison among many listed analyses, and the record does not report multiplicity control. It should not be treated as a definitive standalone conclusion.

The data also do not establish broad clinical benefit, harm, or equivalence between the dose groups. The record does not report several details needed to assess the full analysis, including participant flow, missing-data handling, analysis populations, and the original sample-size justification. Serious adverse event counts and deaths are reported descriptively, without enough information to attribute events to treatment.

In short, the posted results are compatible with a range of possible differences in the primary before-incision lactate measure. The findings do not settle the rewarming hypothesis or the effects on unreported outcomes. A nonsignificant comparison is not proof of no effect, just as a secondary p-value below a conventional threshold does not by itself establish a robust treatment effect.

18. Why This Trial Matters Statistically

This trial illustrates why the estimand—the exact outcome, comparison, and timepoint being analyzed—matters as much as the clinical hypothesis. The rationale concerns infusion during rewarming, while the primary measure is plasma lactate before incision. Statistical analysis can describe the stated measurement precisely, but it cannot make that measurement represent a later response that is not recorded in the primary endpoint.

It also demonstrates why a p-value should be read with an effect estimate and uncertainty interval. The recalculated primary mean difference is -0.1 mmol/L, and the interval includes zero. This conveys both the observed direction and the uncertainty, whereas a p-value alone would not show the range of effects compatible with the summary data. The registry’s own reported p-value is distinct from the summary-based recalculation and should not be silently substituted for it.

Small outcome counts and variability affect precision. The planning illustrations show how the required number of participants per arm changes with the effect size targeted, but they are not evidence that the trial was originally designed with those assumptions. The original design justification is not reported. This distinction helps prevent retrospective planning calculations from being mistaken for observed power or original protocol decisions.

Finally, a trial with many outcomes requires careful attention to multiplicity, analysis populations, and missing data. The registry lists numerous measures and analyses but does not report a multiplicity strategy or key analysis details. Reading secondary findings as exploratory, while keeping the primary endpoint and its timing in focus, is a statistically cautious way to interpret the record.

19. 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 primary endpoint’s timing is a specific limitation: plasma lactate is listed before incision, whereas nitroglycerin is described as being infused during rewarming. The registry does not report a later primary lactate measurement or explain this timing relationship. The primary result therefore cannot directly address a change during the intervention period.

The arm summaries include 32 participants for high-dose and 31 for low-dose, while registry enrollment is 80. Participant flow and the reasons for the outcome counts are not reported. The analysis population and handling of missing outcome data are also not reported, so the completeness and composition of each analysis cannot be fully assessed.

The original sample-size rationale, allocation procedure, masking details, and statistical analysis plan are not reported in the registry record. The report identifies a two-sided t-test but does not provide further details about the test variant or diagnostics. The registry also does not state whether interim analyses or stopping rules were used.

Many outcome measures and analyses are listed, without a reported multiplicity strategy or clear secondary-outcome hierarchy. This makes secondary p-values more vulnerable to chance findings. Quantitative summaries for time to extubation and length of ICU stay are not reported in the available record, limiting assessment of those named outcomes.

Finally, adverse-event counts are sparse and lack detail on timing, attribution, and event definitions. They can be described but do not support a causal safety comparison. These limitations qualify what the registry summaries can establish; they do not by themselves show that the trial procedures were inadequate.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Nitroglycerin Infusion During Cardiac Surgery — NCT01901419.
• Registry record last updated 2020-11-24; status last verified 2020-10.
• Results first posted 2020-11-24.
• 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.

23. Record Summary

NCT01901419 is a completed, randomized, double-masked, parallel-group trial sponsored by Tri-Service General Hospital (TSGH), with registry enrollment of 80. It compared high-dose nitroglycerin infusion, 1-5 mcg/kg/min, with low-dose infusion, 0-0.1 mcg/kg/min, during cardiac-surgery rewarming.

The primary outcome is plasma lactate before incision. The arm means are 1.1 mmol/L and 1.0 mmol/L, respectively; the unadjusted recalculation gives a mean difference of -0.1 mmol/L with an interval including zero. The registry reports p = 0.618 for its two-sided t-test, while the summary-based recalculation gives p = 0.38.

Selected secondary results and adverse-event counts are also reported. The registry does not report the original sample-size justification, multiplicity strategy, participant flow, missing-data handling, or detailed analysis populations. The primary outcome’s before-incision timing does not directly measure a response during rewarming.