Bedfont NOxBOX mobile, Technical Manual

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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 efficient 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 fill 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 fixed outlet pressure of 4 bar when the cylinder valve is open, and a
high-pressure contents gauge displays the actual fill-pressure of the cylinder.
A supply line hose connects between the regulator and the NOxBOX
i
system via
quick-connect fittings. 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 flow pattern and volume are detected by the
NOxBOX
i
system, and the flow 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 flow. This is a backup
delivery function that delivers the NO gas flow rates between 50-600ml. You can select
the flow 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.