Hemolysis is the most common pre-analytical error in emergency department (ED) laboratory specimens and can lead to false elevation of intracellular analytes (potassium, LDH, AST, hemoglobin), resulting in misdiagnosis and unnecessary testing. Blood samples in the ED are transported to the laboratory either by pneumatic tube systems (PTS) or manually by personnel. Although PTS shortens turnaround time, the forces generated during transport may damage erythrocyte membranes and promote hemolysis. Evidence on whether PTS increases hemolysis compared with personnel transport is inconsistent, partly because existing studies use parallel-group designs that cannot control for between-subject biological variability, and partly because findings differ across PTS brands and configurations. The Sumetzberger Power Control PTS installed at Marmara University Pendik Training and Research Hospital (speed 4-5 m/s, 120 m, cushioned capsule) has not been prospectively validated for hemolysis risk. This study uses a randomized, split-sample (within-patient matched), single-blind design in which two simultaneously drawn yellow-cap tubes from the same patient are randomly allocated, one to PTS and one to personnel transport, thereby eliminating between-patient variability. The primary outcome is the Hemolysis Index (HI) category (ordinal scale 0-5 corresponding to free hemoglobin thresholds of \<50, 50-99, 100-199, 200-299, 300-500, and \>500 mg/dL). Secondary outcomes include the rate of clinically significant hemolysis (HI \>= 1 / free Hb \>= 50 mg/dL) and the correlation between transport time and HI.
Adults aged 18 years or older
Presenting to the emergency department of Marmara University Pendik Training and Research Hospital
Venous blood draw required for routine clinical care, allowing two yellow-cap (serum separator) tubes to be drawn from the same venipuncture
Written informed consent provided by the participant or, where the acute clinical condition of the participant prevents this, by a legal representative
Known underlying hemolytic disorder (e.g., hemolytic anemia, sickle cell disease, G6PD deficiency, autoimmune hemolytic anemia, or TTP/HUS)
Macroscopic hemolysis visible in the sample tube immediately after phlebotomy
Age younger than 18 years
Crossover
Pneumatic Tube System Transport
Procedure/SurgeryBlood sample transport using the Sumetzberger Power Control pneumatic tube system (Sumetzberger, Austria). The system operates at a speed of 4-5 m/s over a distance of approximately 120 meters using cushioned capsules. Transport duration ranges between 50 and 90 seconds.
Manual Personnel Transport
Procedure/SurgeryBlood sample transport performed manually by emergency department staff carrying the tube on foot from the phlebotomy area to the central clinical laboratory. Transport is dispatched simultaneously with the paired pneumatic tube sample.
Hemolysis Index (HI) Category in PTS-Transported vs. Personnel-Transported Tubes
Ordinal 6-category HI scale (0=\<50, 1=50-99, 2=100-199, 3=200-299, 4=300-500, 5=\>500 mg/dL free hemoglobin) as reported by the automated analyser. Higher category indicates more hemolysis. Compared between PTS and personnel tube from the same patient (paired).
Rate of Clinically Significant Hemolysis (HI ≥ 1) in PTS-Transported vs. Personnel-Transported Tubes
Proportion of tubes with HI category ≥ 1 (free haemoglobin ≥ 50 mg/dL), the threshold at which samples are typically flagged for rejection by the laboratory. Dichotomous outcome (0 vs ≥1) compared between matched tube pairs.
Spearman Correlation Between Tube Transport Time and HI Category
Spearman rank correlation coefficient (ρ) between recorded PTS transport time (seconds, 50-90 s range) and the HI category of the PTS tube. Exploratory analysis.
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