Bedfont NoxBox - Gas Delivery and Monitoring

41
The NOxBOX
i
systemperformstwomainfunctions:
• DeliverycontrolofNOintotheinspiratorylimbofthepatientventilatorcircuit.
• SimultaneousmonitoringoftheinhalantsampletoverifytheNOdoseleveland 
 theoxygenconcentrationbeingdeliveredtothepatientandensuringNO
2
levels
are within acceptable limits.
Thesetwofunctionsoperateincoordinationtoenableefcientdosedeliveryandmaintain
consistentdrugadministrationconditions.Intheeventofaproblemoccurringineitherof
thefunctions(e.g.adeliverymodulefailure),thesecondaryfunction(e.g.monitoring)will
stillfullyfunction.Inthesameway,duringbasicmaintenanceroutinessuchas
zero-calibration,thedeliverychannelremainsuninterrupted.
Thesystemhasanon-electronicemergencybackupdeliverymodetoensurethat,inthe
eventoffailureoftheautomaticintelligentdeliverysystem,theNOdrugcanstillbead-
ministered to the patient whilst a substitute system is implemented.
6.1 Gas Delivery System
WARNINGS:
At room temperature and atmospheric pressure, nitric oxide (NO)
is a colourless, odourless, toxic, gas. NO is a corrosive and
oxidizing substance. Refer to the gas MSDS for safe handling
information.
NO can combine with atmospheric oxygen to form nitrogen
dioxide (NO
2
). NO reacts rapidly with oxygen to produce NO
2
,
which may further react to form nitric and nitrous acid in the
presence of water (H
2
O). This unwanted by-product needs to be
monitored carefully and kept below 0.5 ppm for most applications
as NO
2
is extremely toxic and a severe pulmonary irritant.
The NO gas is a mixture of NO buffered in nitrogen. Stored in high pressure gas
cylindersatanominalllof150–200bar(supplierdependent).
Ahigh-pressureregulatorisattachedtothevalveconnectorofthegascylinder.This
regulatorissettoaxedoutletpressureof4barwhenthecylindervalveisopen,anda
high-pressurecontentsgaugedisplaystheactualll-pressureofthecylinder.
A supply line hose connects between the regulator and the NOxBOX
i
systemvia
quick-connectttings.The NOxBOX
i
system trolley can accommodate up to two NO
cylinders,whichareconnectedtotheinletports1and2attherearofthesystem
respectively.
Inside the NOxBOX
i
system,thetwogaslinesarecombinedthrougharobustautomatic
change-oversystemintoasingleinletpoint.Theautochange-overfunctionwillonly
drawfromonesupplycylinderuntilthatcylinderisspent.Oncethishappens,the
secondlineisopenedtoensureacontinuousdeliveryofNOtothepatient.
TheNOdoseisentered,theventilatorowpatternandvolumearedetectedbythe
NOxBOX
i
system,andtheowofNOdeliveredintothepatientcircuitiscontrolledto
achievethedesireddoseforthegivenconditions.
Intheeventofamalfunctionintheautomaticdeliverycircuit,thesystemalarmswill
soundtoinstructyoutoengagethemanualoverrideow.Thisisabackup
deliveryfunctionthatdeliverstheNOgasowratesbetween50-600ml.Youcanselect
theowratewhichbestmatchesthecurrentpatientdoselevel,usingeitherthe
on-boardsimpledeliverycalculator,orbyreferringtothedoselook-upchartsprovided
with the NOxBOX
i
system.