Role of biocompatible IV infusion pumps in hemodynamic instability

Biocompatibility is defined as the ability of a material or equipment to perform without inducing a clinically significant response. We started using an IV infusion pump calibrator (BIOTECH) in 1999 for quality control. Very soon we observed that some peristalticIV pumps presented with a phasic variation of flow, although the average flow was well calibrated (and used to be categorized as so). Theoretically, this could have a clinically significant impact in the delivery of vasoactive drugs with fast and short action, such as nitroprusside or norepinephrine. We tested three different brands of pumps, two peristaltic (A, n = 10; and B, n = 13) and one syringe pump (C, n = 5) at a flow of 50 ml/min for 20 min. The average flow was 48.5 ± 3.4 ml/min, 51.6 ± 0.4 ml/min and 52.6 ± 2.0 ml/min, respectively (P < 0.001). We measured the highest and the lowest peak flow in each graph and calculated the maximum percent variation ([max-min]/average flow): 26 ± 7%, 28 ± 7% and 9 ± 3%, respectively (P < 0.001). During the 20 min of observation, the number of phases (plus and minus peaks) was 13.2 ± 2.5, 8.9 ± 4.5 and 16.8 ± 3.0, respectively (P = 0.002). Therefore, pump typeB had the highest variation with phases that lasted longer. The most extreme case was a typeB pump, which showed a 32% variation in flow (from 62 to 46 ml/min) with plateaus lasting for up to 4 min and 27 s. In conclusion, IV infusion pumps may have phasic flow variations with long-lasting plateaus that could have an impact on the delivery of vasoactive drugs, possibly worsening hemodynamic instability.