PrinterNox Operating Manual

PrinterNOx Operating manual I. Important safety information - English Nitric oxide is a highly toxic gas, exposure to levels as low as 200 parts per million (ppm) may be fatal even after very short exposures, and prolonged exposure to much lower levels may be harmful. All users of nitric oxide must familiarise themselves with the appropriate safety regulations. When calibrating the PrinterNOx monitor it is important to ensure that calibration gas is adequately vented and safely exhausted. Nitric oxide reacts with oxygen in air to form nitrogen dioxide, an extremely toxic gas with a maximum allowable industrial ambient level of 5ppm. The PrinterNOx nitric oxide/nitrogen dioxide monitor has been designed to the highest standards and incorporates many inbuilt self-checks. As with any measurement device, however, malfunction is possible. When used in the administration of nitric oxide the PrinterNOx must not, therefore, be incorporated as a primary part of the NO delivery system, but rather as a safety check on the delivery system. The delivery system should be constructed in such a way as to minimise possible errors. CareFusion Ltd does not accept any liability for injury resulting from malfunction and failure to follow these guidelines. Failure to follow instructions in the remainder of this manual may also result in dangerously inaccurate measurements being obtained. 3

Introduction The PrinterNOx is a combined Nitric Oxide / Nitrogen Dioxide monitor based on electrochemical fuel cells and may be operated directly from the mains power or from the internal rechargeable NiCad battery pack. Fuel cells work through the reaction of the target gas with an electrolyte at one electrode and oxygen (from ambient air) at the other. This reaction generates an electrical current proportional to gas concentration. In comparison with other technologies (such as chemiluminescent detectors) electrochemical sensors are compact, inexpensive and much easier to use with zero warm up time and simple calibration. The PrinterNOx is designed to monitor delivered NO used as a therapy for adult respiratory distress syndrome and pulmonary hypertension on ventilated patients. The more toxic and non therapeutic by-product, NO2, is also monitored. The NO measurement has a resolution of 0.05 parts per million (ppm) with a full scale of 100ppm and the NO2 measurement has a resolution of 0.05ppm with a full scale of 20ppm. The gas to be monitored is sampled using a constant flow (250ml/min), low dead space, sidestream system. The system includes a water trap, with integral hydrophobic filter, and humidity conditioning circuit to protect the fuel cells against extremes of humidity and particulate contamination. The measurements are displayed on a large graphic liquid crystal display and can be printed as a chart, on the integral thermal printer, together with calibration due date and alarm settings. The last 24 hours of NO and NO2 measurements taken are recorded and stored in the internal battery backed memory and can be printed or uploaded on the RS232 interface for computer storage. The PrinterNOx includes a number of safety features and alarms. These include upper and lower alarms for NO and an upper alarm for NO2. An external alarm cable is available, and when connected to a NO delivery system, is used to trigger an alarm or initiate a safe operating mode if high concentrations of gas are detected. This concentration is 100ppm for NO, 9ppm NO2 or alarm level whichever 4

is the greater. The flow of gas in the sampling line is continuously monitored and an alarm sounded if the line is occluded or the water trap is full. A low battery condition is also alarmed. The PrinterNOx has been designed with ease of use and reliability as of foremost importance. To ensure accurate results, however, it is essential to familiarise yourself with the contents of this short manual.

Medical Use Nitric oxide (NO) is evolving as a novel therapy used to reduce pulmonary arterial pressure and improve gas exchange in paediatric and adult intensive care settings. The NO is usually added to the ventilator circuit from a cylinder of NO in nitrogen with a concentration up to 1000ppm and diluted in the circuit to between 1 and 40ppm. Therapeutic concentrations must be well controlled as levels as low as 100ppm may cause lung injury. For safety reasons sources with greater than 1000ppm NO should not be used. Lower concentrations carry less risk either to the patient in the case of accidental overdose, or to the hospital staff in the case of leakage. However, if moderately high doses of NO are to be administered then the decrease in the maximum FiO2 must be considered and is given by the relationship: FiO2 (max.) = (1 - Required NO Conc./Source NO Conc.) X 100% Therefore, if 40ppm is required from a source of 500ppm NO in nitrogen then the maximum oxygen available would be: FiO2 (max.) = (1 - 40 / 500) X 100% = 92% 5

Methods for therapeutic administration of nitric oxide depend on the exact type of ventilator and ventilator circuit to be used and have not yet been standardised. It is therefore the responsibility of the user to pay due regard to current medical practice when using the unit to monitor concentrations of inhaled nitric oxide and nitrogen dioxide.

NO2 Production Nitric oxide in the presence of oxygen undergoes the following chemical reaction to form nitrogen dioxide, (a more toxic gas than nitric oxide): 2NO + O2 → 2NO2 The rate of conversion is highly dependent on the NO concentration and this has some important implications for the NO delivery system. Firstly, sources of NO with excessively high concentrations should be avoided. Secondly, the administered concentration should be kept as low as is clinically acceptable. Finally, the administration system should mix the incoming NO quickly and effectively to rapidly reduce its concentration to the therapeutic level where NO2 production will proceed at a much slower rate.

Environmental Safety To eliminate environmental pollution with NO and NO2 the PrinterNOx is supplied with two NOxSORB chemical scavengers for removing these gases from the exhaust. The NOxSORB works by converting NO to NO2, which is then chemically absorbed. 6

Connect a NOxSORB to the exhaust of the PrinterNOx, as shown overleaf, orientated such that the arrow is pointing away from the instrument. The NOxSORB should be replaced after 24 hours or when the mauve spheres turn dark brown. When re-ordering please quote 36-SORB100 for a box of 10 of 36-SORB200 for a box of 20. Environmental pollution with NO and NO2 may also arise when leaks are present in the connections to the source of NO.

Operation Before operating the PrinterNOx, ensure that the unit has been fully charged using the AC adapter supplied. (See Charging Procedure.) The PrinterNOx may also be operated with the internal rechargeable batteries. Connect the water trap with integral hydrophobic PTFE filter and sampling line to the PrinterNOx as shown below:

Water trap retaining screws

NOxSORB PrinterNOx

Water Trap 1 Micro Medical

Alarm

2

3

6

7

8

PAPER

C AN C EL

4 9 C H AR G IN G

5

Exhaust port

0 EN T ER

Sampling Line

Switch on the PrinterNOx. Please note that the water trap must be used at all times during measurement to avoid contamination of the fuel cells.

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The on/off switch is located at the rear of the unit:

On/Off switch

Contrast

Display contrast adjustment

O

1

External alarm socket

Power Input 500mA 12V

External Alarm

AC Adapter socket

RS232/ Analogue Output

RS232 socket

An introductory screen giving the software version will be displayed briefly:

MICRO MEDICAL PrinterNOx V X.XX

During this time the following information will be printed:

12/04/95 16:14 NO calibration due : 01/01/96 NO2 calibration due : 07/01/96 NO upper alarm : 15 NO lower alarm : 5 NO2 upper alarm : 4

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This information can be checked and the date, time, calibration or alarm settings may be adjusted prior to performing a measurement. (See sections on Setup, Calibration, and Set Alarms) The calibration due date is set to occur thirty days after the last calibration. However, calibration may be performed at any time before this date to improve measurement accuracy. Measurements can be made after the calibration due date has passed but consideration must be given to the gas sensors which exhibit a slow decline in sensitivity over time. This loss of sensitivity is typically less than 2% per month but could be more if they are exposed to adverse conditions such as exposure to gas concentrations above the measurement range or to solvents such as alcohol. If the calibration due date has passed then the following reminder will be displayed both after the introductory screen and when commencing measurement:

Calibration due! NO 12/12/95 NO2 1/4/96 Press ENTER to Continue Once ENTER is pressed the first menu is displayed and allows selection of several options:

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Select Option 1 Measurement 2 Calibration 3 Set Alarms 4 Report to printer 5 Status 6 Setup 7 Calculate Flow Whilst this display is active the sampling pump is turned off, measurements are not taken, and the gas level alarms are inactive. If no options are selected then the unit defaults to option 1 “Measurement” after 45 seconds. This is done so that the unit defaults to monitoring gas levels with alarms activated in the event that the instrument was inadvertently left on the first screen or was switched off and on. During all other operations, a short warning alarm will occur, after 45 seconds of inactivity, to remind the user that measurement mode is not operational.

1. Measurement To obtain maximum accuracy from the measurement careful consideration must be given to the NO administration system in use. Gas measurement with ventilators producing cyclic flows may give an overestimate or under estimate of the average NO concentration. This is due to localised variation of NO concentration within the delivery system. Dependent on the measurement point, therefore, the sampled average may not correspond to the delivered average. It is therefore important to ensure that the NO delivery system is designed to avoid large variations in the level of delivered NO. 10

The PrinterNOx utilises a sidestream gas system, which is servo controlled to sample at a constant rate of 250 ml/min. By supplying the gas sensors with this constant flow, a high degree of accuracy and sensitivity can be achieved. To carry out NO / NO2 measurement, press “1”. The sampling pump will start and the following screen will be displayed:

15 5 4

NO 000 . NO2 000 .

p p m

Press ENTER for menu The system should now be tested for leaks by occluding the sampling line. The pump will be heard to rise in pitch as the servo system tries to overcome the restriction. As the pump cannot maintain the required flow rate then the measurement will cease to be displayed, the pump will continue to run, and the following message will be displayed:

Gas Line Occluded or water trap full Please clear blockage or empty water trap and filter.

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When the occlusion is removed, the display will automatically revert to the measurement screen. Repeat this procedure by occluding the exhaust port. The sampling line should now be connected to the administered gas, normally as close to the patient as possible. The sampling port must be positioned in such a way that water cannot enter the tubing, causing rapid filling of the water trap. If the gas line appears to be continuously occluded, remove the water trap and empty any water into a suitable container. Ensure that there is no occlusion on the exhaust port. Under exceptional circumstances, water may pass through a damaged water trap and obstruct the inlet to the PrinterNOx. In this case turn the unit off and draw any liquid out of the inlet with a syringe connected directly to the inlet. Replace the water trap with a new one, turn the unit on, and return to the measurement screen. On the left-hand side of the NO legend are the upper and lower alarm levels for NO. On the left-hand side of the NO2 legend is the upper alarm level for NO2. On the bottom line, the rectangle will blink on or off every time a measurement is updated (every 2.6 seconds) to indicate correct functioning of the instrument. The gas concentrations are given in parts per million (ppm). If the printer option is turned on (see Setup section), then the following printout will be obtained during measurement:

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12/04/95 16:14 NO calibration due : 01/01/96 NO2 calibration due : 07/01/96 NO upper alarm : 15 NO lower alarm : 5 NO2 upper alarm : 4

Patient

:...

Hospital

:...

Technician

:...

5

NO

15

0

NO2

4

1715

1730

Spaces for entering the patient name or ID, hospital name, and technician name are provided. This is followed by the axes for the NO and NO2 graphs. These graphs are auto scaled to the current alarm settings. A section of the graph will be printed once every 32 samples and includes a time stamp every 15 minutes on the left-hand side. Each dot on the graph represents the average of 4 measurements.

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If the measured gas goes outside the range of the alarm settings then an audible alarm and a red flashing visual alarm will be generated. In addition, the relevant indicator on the liquid crystal display will flash. The graph is then replaced by a printout of each individual measurement together with a time stamp and an alarm indicator as shown below:

12/04/95 16:14 NO calibration due : 01/01/96 NO2 calibration due : 07/01/96 NO upper alarm : 15 NO lower alarm : 5 NO2 upper alarm : 4

Patient

:...

Hospital

:...

Technician

:...

5

NO

15

0

NO2

4

1715

1730

1741 1741 1741 1742

Alarm NO = 22.3 Alarm NO = 22.4 Alarm NO = 23.1 Alarm NO = 23.0

NO2 = 1.85 NO2 = 1.95 NO2 = 2.10 NO2 = 1.90

If the NO measurement exceeds 100ppm or NO2 exceeds 9ppm then the external alarm, accessible at the rear of the instrument, is 14

activated. If the NO2 alarm level is set above 9ppm, then the external alarm comes into operation at the set level for NO2. The external alarm consists of a pair of normally closed contacts, which are latched open when the above condition occurs. This can be used to sound an external alarm or switch a NO delivery system into safe operating mode in systems equipped with this facility. The display will change to:

15 5 4

NO 148 . . NO2 987

p p m

CUT OUT: PRESS ENTER Measurements will continue but it should be noted that the measurement range would be limited to just over 100ppm NO and 20ppm NO2 and that the actual concentrations could be significantly higher. Press enter to clear the external alarm when the reading drops below the external alarm levels. When this condition occurs, the cause should be immediately investigated. However, caution should be observed when shutting down the supply of NO, as the sudden cessation of NO can be more detrimental to the patient than a temporary overdose of NO. Ideally, the external alarm should be used to switch the delivery system into a ‘safe’ operating mode or switch in a backup supply.

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Should the water trap fill during the course of the measurement, it will overflow into the integral hydrophobic PTFE filter, cause an obstruction, and the following message will be displayed:

Gas Line Occluded or water trap full Please clear blockage or empty water trap and filter.

Unscrew the two retaining screws, and remove the water trap from the PrinterNOx. Empty the accumulated water into a suitable container by connecting a syringe (20ml minimum size) with the adapter supplied and pushing air through the assembly as shown below.

20 15 10 5

Syringe adapter

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Reconnect water trap to the PrinterNOx and secure with the two retaining screws. If the ‘Gas Line Occluded’ message reappears, disassemble and replace the water trap with a new one. Under exceptional circumstances, water may pass through a damaged water trap and obstruct the inlet to the PrinterNOx. In this case turn the unit off and draw any liquid out of the inlet with a syringe connected directly to the inlet. Replace the water trap with a new one, turn the unit on, and return to the measurement screen. The alarm may be muted for a 45-second period by pressing the CANCEL key.

2. Calibration If the instrument is in use immediately before calibration is attempted, then the system should be purged with clean air. This may be done by disconnecting the water trap from the instrument and running the instrument in measurement mode for 5 minutes. To carry out sensor calibration press 2 and the following screen will be displayed:

Disconnect instrument from gas sources. Press ENTER to start Press CANCEL to abort

The PrinterNOx requires clean air free from any NO or NO2 so that the sensors can be zeroed.

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With the water trap disconnected, press enter and the display will change to:

Zeroing *... Press CANCEL to abort

The sampling pump will start and the PrinterNOx will monitor the output of both sensors until a stable reading is obtained. During this time, a line of asterisks appears on the screen to indicate correct operation. When zeroing is complete the readings for the NO and NO2 sensors are written into the battery backed memory and the display is changed to:

Calibration ----------1 Calibrate NO 2 Calibrate NO2 3 Exit

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Press “1” to calibrate NO and the display will change to:

Enter NO calibration gas concentration: 00.0 ppm

Enter the required gas concentration using the DELETE key to correct any mistakes and press ENTER. The display will change to:

Pass calibration gas through instrument Press ENTER to start Press CANCEL to abort

CareFusion can supply calibration gas (25ppm NO in nitrogen and 10ppm NO2 in air) complete with a control valve for simple and economic user calibration. The gas is supplied in convenient, disposable, aluminium canisters containing 58 litres of gas (Cat No 36-GAS100 for 25ppm NO in nitrogen and 36-GAS200 for 10ppm NO2 in air). A flow regulator pre-set to deliver 500ml/min is available separately, Cat No 36GAS500. With careful use, approximately 45 calibrations can be obtained from each canister. 19

Screw the control valve on to the canister and connect to the PrinterNOx with the water trap connected as shown below: Pre-set Flow Regulator (500ml/min)

Pressure Guage 0

1000 psi USE NO OIL

Control Valve

One Way Relief Valve

25 ppm Nitric Oxide in Nitrogen

PrinterNOx

OR 10 ppm Nitrogen Dioxide in air Micro Medical

Alarm

1

2

3

4

6

7

8

9

PAPER

CANCEL

CHARGIN G

5 0 ENTER

Slowly turn the control knob fully anti-clockwise. This will then supply a flow of approximately 500ml/min. As the PrinterNOx samples at a rate of 250ml/min then 250ml/min will be vented through the one way valve.

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Press ENTER on the keypad and the display will change to:

Calibrating NO *... Press CANCEL to abort

The sampling pump will start and the PrinterNOx will monitor the output of the NO sensor until a stable reading is obtained. When stability has been achieved the calibration factor, time and date are written into the battery backed memory and the display returns to the previous screen. Remove the control valve by turning anticlockwise to stop the gas flow. The NO2 sensor can now be calibrated using the same procedure if required. Within the lifetime of the sensors, zero drift of more than 10ppm (1ppm for NO2) or a calibration drift of more than 40% implies abnormal ageing of the electrochemical cell. If these errors are detected during the zeroing procedure or the calibration adjustment then the following will be displayed:

------- ERROR ------Reading out of range: Check gas supply and try again. Refer to manual if error recurs. Press any key

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