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Abstract
Background and Aims Recently a novel infusion pump strategy, mimicking manual intermittent bolus (MMIB) with increased flowrate, has been developed.This supposedly differs from other infusion pumps as its injectate is given as a bolus rather than infusion. This study aims to compare the effects of continuous infusion regimen with MMIB regimen in five different nerve blocks in fresh human cadavers.
Methods The Institutional Review Board of Ethics of Penn State College of Medicine, USA approved this study for exemption for being a nonhuman. Bilateral ultrasound-guided peripheral nerve catheters (Pajunk® E-cath kit) were placed at five locations in two fresh cadavers.10ml of iodinated contrast material diluted in methylene blue dye were injected using either a Smith CADDTM or PainGuard™ pump. Within 20-min of injection the cadavers scanned using computer tomography (CT), then cadavers were taken to a laboratory and anatomical dissection of the cadavers was subsequently performed. The extent of methylene blue staining of muscles, nerves, fascial planes and tissues in each hemi-abdomen was photographed and documented. Descriptive statistics and unpaired t-tests were performed.
Results The MMIB infusion regimen provided greater spread for the four injections in both cadavers compared to the continuous regimen, (figure 1 and 2) but these differences were not statistically significant. (table 1a and 1b) There was significance (p<0.001 in the extent of dye spread between the male and female cadavers (table 2a and 2b).
Conclusions This preliminary study demonstrates a probable role of increase in flow rate of the infusion in future practice of continuous nerve blocks.