Efficacy and Safety of Low Pressure (-4cmH2O) Suction Compared With Physiologic Pressure (-8cmH2O) Suction Using Digital Continuous Suction System After Pulmonary Resection: A Prospective Randomized Controlled Open-label Study
Phase: NA
Conditions: Lung Cancer Patient
Sponsor: Seoul National University Hospital

Study Protocol and Statistical Analysis Plan 
Official Title: 
Efficacy and Safety of Low Pressure (–4 cmH₂O) Suction Compared With Physiologic 
Pressure (–8 cmH₂O) Suction Using a Digital Continuous Suction System After Pulmonary 
Resection: A Prospective Randomized Controlled Open-label Study. 
ClinicalTrials.gov Identifier: 
NCT number pending 
Document Date: 
August 27, 2025 
Version: 
Protocol and Statistical Analysis Plan, Version 1.2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
Protocol Synopsis (English, v1.2) 
Official Title 
Efficacy and Safety of Low Pressure (–4 cmH₂O) Suction Compared With Physiologic 
Pressure (–8 cmH₂O) Suction Using a Digital Continuous Suction System After Pulmonary 
Resection: A Prospective Randomized Controlled Open-label Study. 
Sponsor / Funding 
Seoul National University Hospital (Biomedical Research Institute). 
Study Period 
From IRB approval through August 30, 2026. 
IRB number : 2507-104-1658 
Design & Setting 
Prospective, randomized, controlled, open-label, parallel-group trial at a single tertiary 
center. 
Population & Sample Size 
Adults undergoing anatomical lung resection (segmentectomy or lobectomy) for 
confirmed or suspected lung cancer at SNUH. Planned N=160 (80 per arm). 
Objective & Hypothesis 
To determine whether maintaining –4 cmH₂O suction on a digital chest drainage system 
shortens chest-tube–related recovery metrics compared with –8 cmH₂O, without 
compromising safety, and to inform an optimal pressure protocol for digital systems. 
 
Interventions (Arms) 
• 
Experimental: A digital thoracic drainage device set to continuous suction at −4 
cmH₂O, initiated on postoperative day 1 after randomization. The assigned 
suction pressure is maintained until chest tube removal unless predefined clinical 
safety criteria require adjustment. Air-leak flow and drainage volume are recorded 
as part of routine postoperative care. 
• 
No interventions: A digital thoracic drainage device set to continuous suction at 

−8 cmH₂O, initiated on postoperative day 1 after randomization. The assigned 
suction pressure is maintained until chest tube removal unless predefined clinical 
safety criteria require adjustment. Air-leak flow and drainage volume are recorded 
as part of routine postoperative care. 
Randomization & Allocation 
1:1 block randomization via the institutional web system. Allocation is concealed until the 
end of surgery; for eligible patients on POD1, the assigned pressure is set (typically 
around 07:00–08:00). 
Consent & Eligibility Snapshot 
Written informed consent is obtained on the day before surgery. Randomization occurs 
only if a measurable air leak persists on POD1 and the chest tube is not removed per 
routine care. Patients with no clinically meaningful air leak on POD1 (e.g., 0–10 
mL/min) are screen-fail and remain in routine care outside the comparative analysis. 
 
Outcomes 
Primary Outcome 
• 
Duration of postoperative air leak (days) 
Description: Daily air-leak flow (mL/min) recorded by the digital chest drainage 
system (≈6 AM). Air-leak resolution is defined as no visible air leak or <10 
mL/min sustained for ≥12 hours with adequate lung expansion on chest X-ray 
and stable clinical status. Duration is calculated in days from randomization 
(POD1) to resolution. 
Time Frame: Time Frame: From postoperative day 1 randomization to the date of 
air-leak resolution, assessed daily, up to 30 days postoperatively or until hospital 
discharge. 
Key Secondary Outcomes 
• 
Chest tube duration (days) 
Description: Number of calendar days the chest tube remains in place during the 
index hospitalization. 
Time Frame: Time Frame: From the date of surgery to the date of chest tube 
removal, assessed during the index hospitalization for up to 30 postoperative 

days. 
Subgroup / Interaction of Interest 
- Effect modification by POD1 air-leak flow: <100 vs ≥100 mL/min. 
 
Protocolized Management Criteria 
Pleurodesis (per protocol) 
Prefer delayed pleurodesis. Perform at POD6 if ≥5 days of air leak with incomplete lung 
expansion; if persistent, consider again around POD10. After pleurodesis, temporarily set 
suction to –20 cmH₂O for ~24 hours; subsequent management at clinician discretion. 
Chest Tube Removal (per protocol) 
Proceed when all are met: 
1. Adequate lung expansion on chest X-ray (a small, asymptomatic apical 
pneumothorax may be acceptable); 
2. 24-hour drainage ≤250 mL and serous/serosanguinous; 
3. Clinical stability. 
 
Sample Size & Timeline 
Sample Size Plan 
Planned N=160 (80 per arm), allowing an interaction test by POD1 air-leak stratum 
(<100 vs ≥100 mL/min) with 1:1 allocation and reasonable power (two-sided α=0.05). 
Timeline (Planned) 
Enrollment Aug 2025–Apr 2026; analysis Sep 2025–Jun 2026; final report Jul–Aug 2026. 
 
Interim Analysis, Monitoring, and Data Handling 
Interim Analysis & Stopping 
One interim analysis at ~50% enrollment using O’Brien–Fleming boundaries (two-sided 
α≈0.005 interim; 0.048 final). Consider early stop for efficacy, safety (imbalanced 
complications), or futility (negligible effect size). Individual-patient safety permits pressure 
adjustment per predefined criteria. 

Data & Safety Monitoring 
PI-led monitoring with designated staff; routine tracking of accrual, randomization, 
protocol deviations, and safety events; periodic aggregate reviews (e.g., every 20 patients 
or monthly). 
Data Management & Privacy 
Coded IDs only; no direct identifiers in research datasets; restricted access to authorized 
personnel; secure storage; retain ≥3 years post-study then dispose per policy. 
 
Statistical Methods 
Analysis Populations 
Primary analysis follows intention-to-treat (ITT). A modified ITT set will exclude 
participants with no primary endpoint ascertainment; a per-protocol (PP) analysis will be 
conducted as sensitivity. 
Primary Endpoint Analysis 
Compare –4 vs –8 cmH₂O using a two-way ANOVA with factors: (1) randomized 
pressure (–4 vs –8) and (2) POD1 air-leak stratum (<100 vs ≥100 mL/min), including the 
interaction term. Assess normality (Shapiro–Wilk); if violated, use an aligned-rank 
transform ANOVA or appropriate transformation. Report effect sizes as mean differences 
(or Hodges–Lehmann median differences) with 95% CIs; two-sided α=0.05. 
Secondary Endpoints 
• 
Continuous variables (e.g., air-leak duration, length of stay, peak air-leak): two-
sample t-test or Mann–Whitney U as appropriate; model-based two-way ANOVA 
mirroring the primary model will be reported as supportive. 
• 
Categorical variables (e.g., pleurodesis performed, suction readjustment, 
postoperative pulmonary complications, 30-day readmission): χ² or Fisher’s exact 
tests; logistic regression (including the interaction term) as supportive. 
• 
Re-intervention rates: analyzed similarly; time-to-event methods considered only if 
censoring arises. 
Covariate Sensitivity 
Pre-specified models may adjust for surgical approach (VATS/RATS vs open), resection 
type (segmentectomy vs lobectomy), and side/lobe if imbalances occur. 

Missing Data 
For secondary endpoints with missingness, perform multiple imputation (assuming 
missing at random) with complete-case sensitivity analyses.