Fig. 4.
In vitro and in vivo adjustment to dose delivery of an ongoing infusion. (A) Conventional and algorithm-driven delivery of methylene blue were compared in vitro. After establishing steady-state delivery, the methylene blue infusions were reduced manually (“turn down the drug pump,” constant carrier flow) or by algorithm-driven control with the intent to reach half of the original steady-state delivery level for 5 min. The methylene blue infusions were then increased manually (“turn up the drug pump,” constant carrier flow) or by algorithm-driven control with the intent to reach twice the original steady state for 5 min before returning to the original baseline. Arrows and vertical lines indicate the time at which dose changes were initiated (N = 5 for algorithm, N = 4 for conventional; data points represent mean ± SD). (B) Effects of norepinephrine infusions on max dP/dt in an animal model. After achieving steady-state hemodynamics, the dose of drug delivered via a 16-gauge catheter was reduced by conventional (“turn down the drug pump”) or algorithm control with the intent to reach to one half of the original steady-state delivery level for 5 min. The drug infusion was then increased by conventional (“turn up the drug pump”) or algorithm control with the intent to reach twice the original steady-state delivery for 5 min before returning to baseline. Arrows indicate the time at which dose changes in the drug infusion were initiated (N = 5 for algorithm, N = 5 for conventional; data points represent mean ± SD).