We performed a non-inferiority in vitro study comparing neonatal PICC lines and UVCs with the standard peripheral 24 G short catheter.

Regular male apheresis donors (blood group O+, cytomegalovirus (CMV) antibody-positive) were consented to participate in this study (N=16). All platelet donations were collected and analysed at the National Blood Centre of the Irish Blood Transfusion Service. Eligible donors were informed of the study and invited to participate 28 days prior to platelet donation. Consent was confirmed on the day of donation. Double platelet donations were collected by apheresis using Trima Accel (Terumo, Tokyo, Japan). Platelets were processed as routine for neonatal-suitable transfusions, including the assessment of pre-release blood cell count (Sysmex XN Series, Sysmex Europe SE, Norderstedt, Germany) and bacterial culture (BacT/ALERT, BioMerieux, Bruz, France). Neonatal platelets are released for transfusion usually on day 2 postdonation.

Platelets were gamma-irradiated, and irradiation was confirmed with RadTag (Sarstedt, Nümbrecht, Germany).

The following polyurethane catheters were used: Premicath 1 Fr/28 G 20 cm (Vygon, Ecouen, France), polyurethane catheter Nutriline 2 Fr/24 G 30 cm (Vygon), polyurethane double-lumen umbilical catheter 4 Fr, 2 20 G lumen (Vygon) and the peripheral 24 G short-catheter Jelco Optiva (ICU Medical, California, USA) as a control. Platelets were also run through ‘no line’, straight into the collection set, to simulate the same handling.

Platelets (60 mL) were drawn from the platelet bag into a 60 mL BD Plastipak (Becton Dickinson, Madrid, Spain) syringe through a B Braun ProSet Sangofix B-Set 200 μm, 11 cm2 filter (B Braun, Melsungen, Germany). The syringes were connected to the infusion lines through a CareFusion PA-80-GC extension set (Sendal, Almaraz, Spain) with a Bionector needle-free access device (Vygon). Platelets were infused through a B Braun Perfusor Space pump (B Braun), with pressure alarms set at maximum (900 mm Hg), as per normal neonatal unit practice for PICC line infusions. Platelets were infused into labelled Compoflex DEHP/PVC 150 mL bags (Fresenius Kabi, Hamburg, Germany) in a 37°C water bath based on neonatal body temperature (figure 1).

Set-up of laboratory transfusions using syringe pumps, lines and water bath.

Infusions were run at 30 mL/hour for 2 hours, mimicking a 15 mL/kg transfusion in a 1000 g baby which would normally be administered over 30 min at the fastest rate of transfusion. To have sufficient transfusate to perform all the testing planned, 60 mL was transfused.

During the transfusions, transfusion-line pressure was monitored by the investigator using the visual scale on the Perfusor Space pump, and the highest pressure level attained was recorded for every transfusion. Following the 2-hour transfusion period, the Compoflex bags were removed from the water bath and dried, the transfusion lines were removed, and the Compoflex bags were heat-sealed using the SEBRA Hand-Held RF Tube Sealing System (Vante Biopharm, Arizona, USA).

Bags were assessed for the level of swirling and the presence of aggregates by a senior medical scientist or a transfusion scientist. Visual swirling assessment was scored from 0 (no swirling) to 3 (optimal swirling) as per Bertolini and Murphy.9 A visual aggregate assessment score was assigned as recommended by van der Meer et al.10 Aliquots of transfused platelet concentrates were then removed from the bag for pH analysis (Roche Omni S, Roche Diagnostics, West Sussex, UK) and automated cell count (Sysmex XN Series, Sysmex Europe SE). Aliquots were also removed for platelet in vitro activation response, estimated by flow cytometry (FACSCanto II Benchtop Flow Cytometer System, BD Biosciences, New Jersey, USA), assessing the expression of CD62P following staining with fluorescein isothiocyanate (FITC)-conjugated anti-CD62P antibody (BD Biosciences).

Statistical analysis was completed using SPSS Version 27. The primary outcome was successful transfusion of platelets. Secondary outcomes included maximum pressure reached on infusion pump during transfusion, presence and degree of swirling in the transfusate, presence of aggregates in the transfusate, platelet count and MPV, and pH and CD62P levels as a marker of platelet activation. As data were not normally distributed, the independent-samples Kruskal-Wallis test was used to determine if there were any significant differences in the post-transfusion parameters between groups.