Infusion pumps Flashcards by Sara Bellas

what are the different methods for setting up an infusion?

electrical vs non electrical methods

non electrical
* single drip count via IV giving set - the droplet size is a set amount and can alter rate by adjustable roller. relies on gravity
* elastomeric pumps

electrical
* volumetric devices - disposable cassette and reservoir system
* peristatilc pumps
* syringe driver - PCA, TCI

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what is an elastomeric pump?

balloon filled with infusion fluid
as elastic of balloon recoils, the fluid is infused
energy comes from stored elastic energy within ballon
downstream flow restrictor to limit the flow
hence rate of fluid is dependant on upstream emptying and downstream restriction

usually around 300ml in balloon

also a compressible resevoir for PCA functon

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what are the pros and cons of elastomeric pumps?

pros - low cost, can be used with PCA, no electricity

however less accurate and single use

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how does the PCA function work on an elastomeric pump?

downstream of flow restrictor so fills
can be pressed to give bolus
automatic lock out because needs time to refill

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what is a volumetric pump?

this is an electrical method for setting up an infusion. it may either be via a disposable cassette and reservoir system OR peristatic pump.

both have a microprocessor and pumps whcih control the volume of fluid being delivered

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how does a dispossbale cassette and reservoir system volumetric infusion work?

theres a small reservoir e.g. 5 ml. the valve is switched such that the infusate fills this reservoir and then the microprocessor causes valve to switch to empty into patient end. this is emptied via a cam driver.

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how does a peristatic pump work?

this is a volumetric pump
infusate from a reservoir goes through compressible tubing to a patient.
there is a series of cam followers which compress the tubing in a wave i.e. peristalsis to push the fluid along.

the tubing needs to be hard wearing and not remain compressed

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how does a syringe driver work?

syringe full of infusion fluid
plunger on the end
a screw is turned to push the plunger and empty the infusion at a set rate

microprocesor allows rate to be set
most accurate form
good for controlled drugs
but more expensive.

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what type of infusion device will a PCA use and how does this work?

PCAs can use elastomeric, volumetric or syringe driver.
there is a control button that delivers a set bolus and lock out period.

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what are the key components of any electrical infusion pump?

A motor / driving mechanism p e.g. screw of a syringe driver, cams of a peristaltic pump

microprocessor - controls pumps and rate - some contain drug libraries and PCA functions and some TCI algorithms.

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what is a TCI pump?

TCI = Target controlled infusion
a user sets a target for either the plasma or effect site.
a syringe driver will have a microprocessor that use algorithms based on height, weight, age to set up an accurate infusion to reach that target.

incoorporates pharmokinetic models.

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what is Diprifusor?

first TCI model created for propofol - used the marsh model

diprivan was the brand name for propofol
prefilled syringers with a chip on them recognised by diprofusor pump
this tag ensured safety but also buisiness scheme

now open label

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do you know any names of syringe drivers using TCIs?

Braun, alaris

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what are the safety features of an infusion device..

Alarms:
* low pressure - dissoconnection
* high pressure - occlusion or tissued - by pressure transducer
* air in line

multiple confirmatory keys - e.g. if you want to give a bolus - prevents accidental.

drug libraries - algorithms to calculate doses and rates of a drug to prevent user error.

antisyphoning and anti reflux valves - sphyphoning is extra fluid by effect of gravity, reflux is pressure downstream causes backflow into line.

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how is a pressure change within infusion device detected?

inline pressure monitors within tubing.

OR the force needed by the pump is measured - as the pump pushes the synringe, a steel plate is also pushed, this will distort the place and cause a change in resistance whcih is proportional to the pressure exerted.

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does an infusion pump alarm at any increase in pressure?

balance between safety and unnecessary regular disruption of flow
so usually set at a threshol
e.g. small kinks will increase pressure but are no problem or having small cannula.

what errors may occur with IV infusion devices?

reflux
siphoning
incorrect drug entered to library so incorrect doses given e.g. 2% propofol but pump thinks its 1%
multiple infusions - have common space, so if you stop one but continue the other, a small amount will still be delivered.
electromagnetic interference of the microprocessor