Objective: To evaluate the change in hemolysis markers in packed red blood cells, administered by gravity infusion in non-valved PICC lines, according to different sizes.

Methods: Experimental study carried out in laboratory under controlled conditions of temperature and humidity. The sample had 36 blood aliquots from 10 packed red blood cells bags with A positive blood type; gravity infusion was used in six 3 French (Fr) PICC and in six 4Fr PICC, totaling 12 experiments divided in three moments: Basal, Free Flow and Controlled Flow. Degree of hemolysis, total and free hemoglobin values, lactic dehydrogenase and potassium were analyzed.

Results: There was an average increase of free hemoglobin (p=0.01) and degree of hemolysis (p=0.01) after Free Flow infusion, with 0.04 average elevation of potassium (p<0.01) and decrease of total hemoglobin (p=0.01) in Controlled Flow. The packed red blood cells infused in 4Fr PICC had average elevation of degree of hemolysis (p=0.03) in Free Flow, and potassium (p=0.03) and degree of hemolysis (p=0.05) in the Controlled Flow. The 3Fr PICC had significant average increase in the degree of hemolysis (p=0.03) and free hemoglobin (p=0.01) after flow control.

Conclusion: The 4Fr PICC were associated to higher changes in hemolysis markers. We infer that the larger size can provide a turbulent flow, contributing to a larger clash among red blood cells.