BACKGROUND of INFUSION EXTENSION LINE:
For anesthesia or conscious sedation of patients undergoing diagnostic or therapeutic procedures in computed tomography or magnetic resonance imaging scans, an extension of infusion lines for continuous drug delivery of anesthetics or vasopressors is often necessary. In this study, we tried to determine if the length of the Infusion Extension Line influenced the time until an alarm sounded after occlusion at the end of the infusion line.
We connected 2 infusion pump systems of the same model with 1, 2 or 3 infusion lines in series or with a spiral nonkinking low compliance infusion line, and started the infusion for 60 s. The end of the infusion line was then occluded by turning a stopcock to occlude the fluid flow. A pressure sensor was connected to the infusion line to record the actual pressure change in the line. The time until the pressure occlusion alarm sounded was measured 5 consecutive times at flow rates of 5, 20, and 50 mL/h.
When using a single infusion line, pressure occlusion alarms were triggered after 2.4 ± 0.1 min for infusion pump 1 and 2.6 ± 0.2 min for infusion pump 2 at 50 mL/h, after 6.6 ± 0.4 min and 5.6 ± 0.5 min at 20 mL/h, and after 23.0 ± 2.8 min and 20.9 ± 3.6 min at 5 mL/h, respectively. When adding a second infusion line, a pressure occlusion alarm was triggered after 27.1 ± 1.8 min for infusion pump 1 (P = 0.1) and after 29.2 ± 1.4 min for infusion pump 2 (P = 0.07) at 5 mL/h. With 3 infusion lines, the pressure occlusion alarm of infusion pumps 1 and 2 were significantly prolonged when compared with 1 infusion line and were released at 31.6 ± 3.0 min (P = 0.01) and 35.1 ± 1.1 min (P = 0.001) at 5 mL/h, respectively. The pressure level triggering an alarm ranged in both infusion pumps between about 900 and 1100 Mbar.
When simulating low flow rate infusions (5 mL/h) as for vasopressor support, occlusion alarm time was critically prolonged, especially with an increased length of infusion lines.
IMPLICATIONS: By increasing the length of infusion lines, the time until an infusion pump triggered a pressure occlusion alarm was critically prolonged, especially at low infusion rates, as is often used for vasopressor support of unstable patients.