In-line pressure within a HOTLINE^® Fluid Warmer, under various flow conditions

Roller pump infusion devices are widely used for rapid infusion, and may be combined with separate warming devices. There may be instances however, where the pressures generated by the roller pump may not be compatible with the warming device. We assessed a commonly used roller pump in combination with a HOTLINE^® Fluid Warmer, and found that it could generate pressures exceeding the HOTLINE^® manufacturers specifications. This was of concern because the HOTLINE^® manufacturer guideline states that not for use with pressure devices generating over 300 mmHg. Pressure greater than 300 mmHg may compromise the integrity of the HOTLINE^® Fluid Warming Set. The aim of this study was to compare in-line pressure within a HOTLINE^® Fluid Warmer at different infusion rates of a roller pump using various sizes of intravenous cannulae. The rapid infusion system comprised a 500 mL-normal saline bag, roller pump type infusion device, HOTLINE^® Fluid Warmer (blood and fluid warmer system), and six different sizes of intravenous cannulae. In-line pressure was measured proximal to the HOTLINE^® (pre-warmer) and proximal to the cannula (post-warmer), at flow rate of 50–160 mL/min. The in-line pressures increased significantly with increasing flow rate. The pre-warmer pressures exceeded 300 mmHg when the flow rate was ≥120 mL/min with 20-gauge, 48 mm length cannula, 130 with 20-gauge, 25 mm cannula, and 160 mL/min with 18-gauge, 48 mm cannula. However, they were <300 mmHg at any flow rates with 18-gauge, 30 mm cannula and 16-gauge cannulae. The post-warmer pressures exceeded 300 mmHg at the flow rate of 140 mL/min with 20-gauge, 48 mm cannula, and 160 mL/min with 20-gauge, 25 mm cannula, while they were <300 mmHg at any flow rates with 18 and 16-gauge cannulae. The in-line pressure within a HOTLINE^® could exceed 300 mmHg, depending on the flow rate and size and length of cannula. It is important to pay attention to the size and length of cannulae and flow rate to keep the maximum in-line pressure <300 mmHg when a roller pump type infusion device is used.