Early Versus Late Release of Sphygmomanometer-Applied Venous Stasis and Phlebotomy-Induced Hemolysis in the Emergency Department: A Parallel-Group Randomized Controlled Trial
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 792
- 试验地点
- 1
研究概览
简要总结
BACKGROUND:
Hemolysis is the most common preanalytical error in emergency department (ED) laboratories, affecting 12-26% of blood samples collected in the ED and leading to test cancellations, repeat venipuncture, delayed diagnoses, and increased healthcare costs. Venous stasis created by tourniquet application during phlebotomy is a recognized contributing factor to hemolysis. While clinical guidelines recommend releasing the tourniquet once blood flow is established, the optimal timing of tourniquet release in relation to tube filling sequence has not been systematically evaluated.
OBJECTIVE:
The primary objective of this trial is to determine whether early release of sphygmomanometer-applied venous stasis (released after the first tube fills) reduces hemolysis rates compared to late release (released after the last tube fills) during routine phlebotomy in ED patients triaged as green or yellow category.
DESIGN:
Single-center, parallel-group, superiority randomized controlled trial with 1:1 allocation ratio. The trial was prospectively registered prior to the enrollment of the first participant.
PARTICIPANTS:
Adult patients (≥18 years) presenting to the emergency department with triage category green (semi-urgent) or yellow (urgent), for whom blood collection is indicated as part of routine clinical care. At least two collection tubes had to be ordered, because the intervention is defined by the timing of cuff release relative to tube filling. Patients requiring blood collection from an intravenous catheter, those with known coagulation disorders, and those who decline to participate are excluded.
INTERVENTIONS:
Group A (Early Release): Sphygmomanometer inflated to 60 mmHg for venous stasis; tourniquet released as soon as blood flow into the first tube (sodium citrate, blue cap) is observed. All remaining tubes are collected after release.
Group B (Late Release): Sphygmomanometer inflated to 60 mmHg; tourniquet maintained throughout all tube filling and released only after the last collection tube completes filling. Tube collection order follows the CLSI H03-A6 standard for both groups.
PRIMARY OUTCOME:
Hemolysis rate, defined as the proportion of serum separator tube (SST/yellow cap) samples with a Hemolysis Index (HI) ≥ 1+ (corresponding to free hemoglobin ≥50 mg/dL), is assessed by the clinical chemistry laboratory analyzer. The outcome assessor (laboratory technician) is blinded to group assignment.
SECONDARY OUTCOMES:
(1) Distribution of ordinal hemolysis index categories (-, 1+, 2+, 3+, 4+, 5+) in SST samples; (2) Proportion of hemolyzed samples requiring repeat blood collection; (3) Duration of venous stasis (seconds), from sphygmomanometer inflation to deflation of the cuff; (4) Complication rate (hematoma or ecchymosis, local swelling, oozing at the puncture site, vasovagal reaction, nerve injury, arterial puncture, or more than two venipuncture attempts).
SAMPLE SIZE:
Assuming hemolysis rates of 12% with late release and 6% with early release, a 2-sided alpha of 0.05, 80% power, and the normal approximation for two proportions with pooled variance, 356 participants per group were required. Allowing approximately 10% attrition, the enrollment target was 396 per group (792 total), and this was reached.
RANDOMIZATION:
A restricted allocation sequence of 792 assignments in a 1:1 ratio, without stratification, was generated with Research Randomizer (randomizer.org) before the start of enrollment. The sequence as implemented is not consistent with any single fixed block size, so no block size is claimed. The complete sequence was fixed before the first participant was enrolled, was embedded in the electronic data collection application, and was not accessible to the enrolling nurse; a participant's allocation was released only after eligibility had been confirmed and the participant had been enrolled. The realized allocation was 396 participants per group.
STATISTICAL ANALYSIS:
Primary analysis: intention-to-treat, comparing hemolysis rates with the Pearson chi-square test with Yates continuity correction; the composite complication outcome was compared with the Pearson chi-square test without continuity correction. Secondary analyses: Mann-Whitney U test for the ordinal hemolysis index distribution and for continuous outcomes; logistic regression for the adjusted odds ratio. A Bonferroni-adjusted alpha of 0.0125 was applied across the four confirmatory secondary endpoints; exploratory analyses used alpha of 0.05. Per-protocol analysis was performed as a sensitivity analysis. Missing primary outcome data were addressed with four prespecified scenarios (complete case, best case, worst case, and a tipping-point analysis); the complete-case analysis is reported as primary.
详细描述
BACKGROUND AND RATIONALE:
Hemolysis is recognized as the leading preanalytical source of error in clinical laboratories, with emergency department settings reporting particularly high rates (range: 12-26%) due to specimen collection under time pressure, use of small-bore intravenous catheters, and challenging venous access. Hemolyzed specimens affect measurements of potassium, lactate dehydrogenase, bilirubin, and other analytes, resulting in clinical misinterpretation, repeated laboratory requests, and procedural delays in a time-sensitive environment.
Venous stasis created by tourniquet application is a physiological perturbation that promotes erythrocyte deformation and lysis through hemoconcentration and shear stress. Clinical guidelines (Clinical and Laboratory Standards Institute, CLSI H03-A6; Turkish Biochemistry Society Phlebotomy Guidelines 2015) recommend that the tourniquet should be released as soon as blood flow is established, ideally within 60 seconds, and not later than the completion of the first collection tube. However, in routine emergency nursing practice, the tourniquet is frequently maintained throughout the entire multi-tube collection sequence to maintain venous distension and reduce the likelihood of failed collection attempts.
This pragmatic trial directly tests whether adherence to guideline-recommended early tourniquet release translates into a clinically meaningful reduction in hemolysis rates compared to the commonly observed late release practice, in a controlled setting using standardized sphygmomanometer-applied venous stasis at 60 mmHg.
INTERVENTION DELIVERY:
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Health Services Research
- 盲法
- Single (Outcomes Assessor)
盲法说明
Outcome assessors (laboratory technicians performing Hemolysis Index analysis) are blinded to group assignment. Each tube carried its own laboratory information system barcode; the allocated group appeared neither on the request nor on the tube, so group allocation was not accessible to laboratory personnel. Participants and care providers cannot be blinded because of the intervention's procedural nature.
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Age 18 years or older
- •Presenting to the emergency department and triaged as green (semi-urgent) or yellow (urgent) category according to the Emergency Severity Index (ESI) or equivalent institutional triage system
- •Blood collection (venipuncture) indicated as part of routine clinical care by the attending emergency physician
- •Ability to provide written informed consent
- •Accessible peripheral vein suitable for standard venipuncture, most often in the antecubital fossa but at the operator's discretion an alternative peripheral site such as the dorsum of the hand (not requiring intravenous catheter placement for blood collection)
排除标准
- •Blood collection performed via an existing intravenous catheter or central venous access device
- •Critical illness or hemodynamic instability, including triage category red (resuscitation) at the time of blood collection
- •Anticoagulant or thrombolytic therapy, or any condition in which collection of a coagulation tube was contraindicated, including a known or suspected coagulation disorder (e.g., hemophilia, thrombocytopenia with platelet count <50,000/uL)
- •Known hemolytic disease, a history of active hemolysis, or another hematological condition associated with baseline elevated hemolysis
- •Red blood cell transfusion within the preceding 24 hours
- •Pregnancy of any gestational age
- •Absence of a peripheral vein suitable for standard venipuncture
- •Local pathology preventing collection from the antecubital fossa: infection, hematoma, burn, active upper extremity injury, lymphedema, an arteriovenous fistula, or the side of a previous mastectomy
- •Only a single collection tube ordered (the intervention requires at least two tubes, because it is defined by the timing of cuff release relative to tube filling)
- •Inability to give informed consent, or declining to participate
- •Previously enrolled in this study (re-enrollment not permitted)
研究组 & 干预措施
Early Release Group (Group A)
Venous stasis is applied using a sphygmomanometer inflated to 60 mmHg. The sphygmomanometer is released (deflated to 0 mmHg) immediately after the first blood collection tube (sodium citrate, 2.7 mL, blue cap) completes filling. The second (SST/gel separator, 5 mL, yellow cap) and third (K2-EDTA, 3 mL, purple cap) tubes are collected without active venous stasis. The tube collection order follows the CLSI H03-A6 guidelines for all participants.
干预措施: Sphygmomanometer-Applied Venous Stasis with Varied Release Timing During Phlebotomy (Procedure)
Late Release Group (Group B)
Venous stasis is applied using a sphygmomanometer inflated to 60 mmHg. The sphygmomanometer is maintained at 60 mmHg throughout the multi-tube collection sequence and released (deflated to 0 mmHg) only after the third and final collection tube (K2-EDTA, 3 mL, purple cap) has filled. This reflects current common nursing practice in the emergency department setting.
干预措施: Sphygmomanometer-Applied Venous Stasis with Varied Release Timing During Phlebotomy (Procedure)
结局指标
主要结局
未指定
次要结局
- Procedural Complication Rate(During the blood collection procedure and up to 30 minutes post-procedure)
- Duration of Venous Stasis(Measured during the blood collection procedure)