CryoStar Operator’s Manual issue C208-2

Operator’s Manual

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Page 1

CryoStar

Ophthalmic Cryosurgery Unit

OPERATOR’S MANUAL (Part No. 1802 6 000 00, issue C208-2)

DORC International bv Scheijdelveweg 2 NL-3214 VN Zuidland Netherlands

Dutch Ophthalmic USA One Little River Road PO Box 968 Kingston, NH 03848 USA

Tel: ++31 181 45 8080 Fax: ++31 181 45 8090

Tel: ++1 800-75-DUTCH or ++1 603 642 8468 Fax: ++1 603 642 8465

email: [email protected]

The CryoStar is manufactured exclusively for DORC by: Spembly Medical Limited Newbury Road Andover, Hampshire SP10 4DR United Kingdom Tel: ++44 1264 365741 Fax: ++44 1264 332113

CE 0086 This document is published to aid authorised distribution, installation and use of the DORC CryoStar ophthalmic console. The information contained herein must not be reproduced in whole or in part without the manufacturer’s prior permission in writing. The manufacturer reserves the right to make improvements in specification or other changes without prior notice. The reader should in all cases consult the manufacturer to determine whether such changes have been made.

CONTENTS page

INTRODUCTION 1.1 1.2

……………………………………………………… ……………………………………………………… ……………………………………………………… ……………………………………………………… ………………………………………………………

5 9 9 9 9

Console ……………………………………………………… Probes ……………………………………………………… Temperature sensing ……………………………………………………… Electrical power ……………………………………………………… Cryogen gas ……………………………………………………… Environmental conditions …………………………………………………… Principle of operation ………………………………………………………

11 11 11 11 11 11 12

Unpacking Preparation Installation

……………………………………………………… ……………………………………………………… ………………………………………………………

13 13 13

Pre-operative checks ……………………………………………………… Using the CryoStar ……………………………………………………… Shut-down ……………………………………………………… Changing cylinders ……………………………………………………… Using the probe adaptor ……………………………………………………

15 15 17 17 17

POST-OPERATIVE PROCEDURES 7.1 7.2

Console Probes Footswitch Hoses Probe Adaptor

OPERATING INSTRUCTIONS 6.1 6.2 6.3 6.4 6.5

2 2 3 3

INSTALLATION 5.1 5.2 5.3

Basic safety ……………………………………………………… Warning notices ……………………………………………………… Safety requirements ……………………………………………………… Hazards arising from improper use …………………………………..…..

SPECIFICATIONS 4.1 4.2 4.3 4.4 4.5 4.6 4.7

1 1

SYSTEM DESCRIPTION 3.1 3.2 3.3 3.4 3.5

……………………………………………………… ………………………………………………………

SAFETY INFORMATION 2.1 2.2 2.3 2.4

About this manual About the CryoStar

Cleaning the console Sterilising probes

……………………………………………………… ………………………………………………………

18 18

………………………………………………….…… ………………………………………………….……

19 19

TROUBLESHOOTING 8.1 8.2

Console Probe

PREVENTIVE MAINTENANCE

SERVICE AND WARRANTY 10.1 10.2

Service Warranty

……………………….…………………...

………………………………………………………. ……………………………………………………….

21 21

CHART : PROBES, TESTS AND SETTINGS

.………………………………… appendix

__________________________________________________________________________

INTRODUCTION

1.1

About this manual

This manual contains instructions for use of the DORC CryoStar, an instrument intended for use in ophthalmic procedures by qualified medical staff. The manual does not contain clinical instructions or recommendations for clinical applications. Use of the CryoStar in any surgical procedure must be at the discretion of the licensed medical authority. It is intended that the equipment be installed by authorised representatives of the supplier, who will also provide suitable training in the preparation, use and care of the CryoStar system. For further information, contact your supplier.

1.2

About the CryoStar

The DORC CryoStar is a system designed for safe and effective application of extreme cold to tissue for the purposes of ophthalmic cryo-surgery. The system is further designed for set-up and operation to be as simple as possible and consists of a control unit (console), a range of interchangeable probes, a footswitch and associated cables and hoses. The mains-powered console provides control of high pressure cryogen gas, which causes cooling as it passes through a micro-orifice and expands into a small chamber at the tip of the probe. Material surrounding the tip is thus frozen according to the Joule-Thompson principle. Control of freezing and subsequent defrosting is by means of a footswitch. The system is capable of recycling after defrost. A full cycle consists of freezing, thawing and de-gassing. The system will operate with both nitrous oxide (N2O) and carbon dioxide (CO2) gases in medical grade form. Although there is no consumption of gas while the unit is at rest, gas used by the probe is not re-used. As a consequence, exhaust gases must be connected to a scavenging system.

__________________________________________________________________________

SAFETY INFORMATION

This section contains important safety information and must be read before using the CryoStar. It is important that the procedures described in this manual are followed carefully. The use of the system in any other manner may lead to injury or damage.

2.1

Basic Safety

2.1.1

The following symbols appear on front panel of the CryoStar.This symbol means that the console is classified as Type B for electrical safety. Note also that the system is rated as Class IIa, according to MDD 93/42/EEC classification, and complies with the following standards:IEC 601-1 and appropriate international variants (EN60601-1, UL2601-1, CSA6011), EN60601-1-2 & FCC15, EN60601-1-4, IEC 878/BS 7139 (Graphical symbols for use on medical equipment) This symbol, located at the lower right corner of the front case, indicates the position of the footswitch connector.

2.1.2

The following symbols appear on rear of the CryoStar.

This symbol means ON (power connection to the mains).

This symbol means OFF (power connection to the mains).

This symbol is to be found on the equipotential point (see section 3.1) This symbol and the accompanying text indicates fuse type.

This symbol means that accompanying documents should be read, including this manual.

2.2

Warning notices

2.2.1

LETHAL VOLTAGES

2.2.2

ELECTRIC SHOCK The CryoStar should not be used if the protective ground conductor is damaged or

Lethal voltages are present inside the CryoStar when it is connected to the mains. Authorised service agents only may remove the covers, and only then when the mains supply is disconnected.

disconnected, otherwise death, injury or damage may occur.

__________________________________________________________________________ 2.2

Warning notices (continued)

2.2.3

EXTREMELY LOW TEMPERATURE Do not touch the probe’s tip when freezing or allow it to touch any object or material other than the target tissue, otherwise injury or damage may occur.

2.2.4

RISK OF EXPLOSION The CryoStar should not be used in the presence of flammable anaesthetic agents or volatile solvents.

2.2.5

FEDERAL LAW (USA) restricts this device to use or sale by or on the order of a physician.

2.3

Safety requirements

2.3.1

It is recommended that the CryoStar be inspected for safety and performance at six-monthly intervals.

2.3.2

The CryoStar must be installed and tested by suitably qualified personnel.

2.3.3

Ensure that the mains supply voltage is within the range specified at the rear of the CryoStar console. Use only the power cable supplied, which must be connected to a hospitalapproved three-pole mains socket fitted with a protective ground conductor. All electrical power cables must be kept clean and dry at all times.

2.3.4

The grounding system in the treatment room must be inspected at regular intervals by suitably qualified personnel. Any interruption of the protective ground conductor may render the equipment dangerous.

2.3.5

Use only fuses of the stated rating and type.

2.3.6

Use only medical grade gas from non-syphon cylinders. Liquid withdrawal (‘Snowmaker’) cylinders must not be used. Gas bottles should be secured in an upright position. Note that the optimum gas cylinder temperature is in the range 20ºC to 25ºC (68ºF to 77ºF).

2.3.7

Exhaust gas must be vented through a scavenging system or into a well-ventilated area. It must not be permitted to vent into an uncontrolled space. It is the operator’s responsibility to ensure safe disposal of waste gases.

2.3.8

In the event that equipment failure is suspected which may in any way compromise safety, immediately disconnect the mains supply and secure the unit against further use. Contact a qualified hospital technician or your supplier.

2.3.9

Under no circumstances should you attempt to alter the shape or any part of the probe.

2.4

Hazards arising from improper use of the CryoStar.

2.4.1

Use of the equipment outside the specified conditions can affect performance.

2.4.2

Contact of the probe with any tissue or material outside the target tissue may cause injury or damage.

2.4.3

Use of probes in damaged condition can affect system performance and/or patient or operator safety.

2.4.4

Failure to maintain the equipment in accordance with recommendations may compromise safety and invalidate the warranty.

2.4.5

Use of a non-sterile probe may present a biological hazard.

__________________________________________________________________________

SYSTEM DESCRIPTION

3.1

Console

The DORC CryoStar console (part number 1802 0 000 01) is based on a rigid ABS enclosure, moulded in two parts. It houses a software-driven module for the control and transmission of high pressure cryogen gas to the probe. The front of the unit contains all displays and controls needed for effective use of the unit. Electrical and gas inlet and exhaust connections are located at the rear of the console.

3.1.1

CONNECTIONS (CONSOLE FRONT)

Probe Socket The connection of the probe to the console is a multi-start, single-turn screw. When the probe connector is inserted into the socket there is a delay before the gas pressure builds up to ensure that the connector position is stable.

Footswitch Connection Freezing and defrosting are controlled by a footswitch. The footswitch plug and socket are keyed to prevent incorrect connection.

__________________________________________________________________________

3.1.2

CONNECTIONS (CONSOLE REAR)

Electrical Mains Connector Mains electricity is fed to the console through a three-pin IEC connector. Use only the cable provided with the unit.

Cryogen Gas Inlet The CryoStar should be connected to the cryogen gas bottle using an approved hose with an appropriate adaptor.

Cryogen Exhaust Cryogen gas exhausts from the rear of the unit via a stub pipe. This pipe is fitted with a sleeved relief valve. This valve must not be obscured. An approved hose should be used to vent the exhaust to a scavenging system or into a well ventilated area. It must not be permitted to vent into an uncontrolled space. It is the operator’s responsibility to ensure safe disposal of waste gases.

Equipotential Point The equipotential point is designed for connecting equipment grounds together when such equipment is being used as part of an integrated system. The CryoStar should not be connected to other equipment without the written authority of the manufacturer.

__________________________________________________________________________

3.1.3

CONTROLS

Pressure Regulator This controls the operating pressure of the unit. Pressure is increased by turning the control knob clockwise.

Total Time Button Pressing down and holding the total time button enables the time display to indicate ‘total freeze time’ (ie: total of all freeze times since last purge). Removal of the probe will re-set the total to zero.

Volume Control Each time a probe is connected to the console, the system is purged. Purging takes 90 seconds, at the end of which time a bleeper sounds, signifying “ready for freeze”. The tone also sounds when powering up the unit. The volume of the signal may be adjusted by holding down the volume control button. Press and hold for volume increase, press and hold again for volume decrease. The effect of the volume control may be heard as the button is depressed.

__________________________________________________________________________

Amber

3.1.4 DISPLAYS AND INDICATORS System Status Three indicators report on system status:ð The amber ‘Busy’ lamp shows the unit is performing an operation during which freezing is either not possible or not recommended. ð The green ‘Ready’ lamp flashes during purge and becomes steady when the system is ready to freeze. ð The blue ‘snowflake’ indicates that the freezing cycle is active.

Time Display Freeze times are indicated in seconds using a row of three 7-segment displays. The timer automatically starts counting up from zero when the footswitch is activated. This means that, unless the footswitch is being used, the timer will always display the duration of the previous freeze. The timer will also show ‘purge countdown’. In this case, the ‘busy’ indicator will light up and the timer count down from 90 to zero.

Pressure Indicator A ‘gas bottle’ symbol will illuminate to show system pressure:ð lower red or amber for under pressure ð green for acceptable range ð upper red for over pressure.

Freezing Indicator For probes fitted with thermocouples, clear visible indication of the probe’s freezing ability is given by the ‘probe’ symbol:ð amber lights indicate an ambient temperature range warmer than 0°C (32ºF). Probes not fitted with thermocouples will always show two amber lights. ð green lights indicate that freezing has started. ð blue lamps indicate optimum performance range. Two blue bars represent an optimum temperature inside the tip for most retinal probes, although all probes will perform sufficiently well when only one blue bar is lit.

__________________________________________________________________________ 3.1.5 SHORTFORM INSTRUCTIONS In addition to the operational displays listed above, the console carries a summary of instructions for use. See the panel at the rear of the console. These instructions are given only as a guide and are not intended to replace the complete procedures contained in this manual.

3.2

Probes DORC CryoStar probes are sealed precision assemblies. Essential features are the surgical tip, the handle, the hose and the gas plug for connection to the CryoStar console. Probe plugs are supplied with protective caps to be used when sterilising.

Probes which may be used with the CryoStar 3R2 Retinal 3B2 Retinal 4G3 Glaucoma 3EX2 Retinal 2C2 Cataract ·89-V-1 Intravitreal 3RO2 Retinal 3T2 Retinal

(1807 0000 30 – DORC reference 1531C) (1807 0000 25 – DORC reference 1533C) (1807 0000 33 – DORC reference 1539C) (1807 0000 34 – DORC reference 1540C) (1807 0000 28 – DORC reference 1530C) (1807 0000 27 – DORC reference 1532C) (1807 0000 24 – DORC reference 1546C) (1807 0000 32– DORC reference 1538C)

CAUTION CryoStar probes must be handled with great care. Do NOT attempt to dismantle a probe – it contains no user serviceable parts.

3.3

Footswitch An electrically operated footswitch, part number 813 6885, is used for controlling freeze and defrost (hold down to freeze, release to defrost). The footswitch plugs into the front of the CryoStar console.

3.4

Hoses

3.4.1 3.4.2

Cryogen Supply Hose, part number 700 6916: FX11 (PTFE core with PVC sheath and stainless steel braiding) Cryogen Exhaust Hose part number 143 8025: Medical grade PVC tubing, non-toxic.

3.5

Probe Adaptor Using the probe adaptor, part number 1802020000, the CryoStar console will function with older style probes designed for use with the DORC Ophthalmic Unit Type 1500-II. The adaptor works with both kinds of probe – those fitted with thermocouples and those without.

__________________________________________________________________________

SPECIFICATIONS

4.1

Console

Overall height: Overall width: Overall depth: Weight:

4.2

315mm (12.4 in) 305mm (12 in) 195mm (7.7 in) 5.4kg (11.9 lb)

Probes

Probes are on average 130mm (5.1 in) long, with 2.15m (7ft) hoses and 110mm (4.3 in) gas plugs. Probes without thermocouples may be identified by a pink sleeve.

4.3

Temperature Sensing

Most retinal and glaucoma probes are fitted with thermocouples.

4.4

Electrical Power

The CryoStar console is powered by single phase mains electricity. ð Voltage: 100 to 264 V ð Frequency: 50 to 60 Hz ð Input power: 40VA ð Fuse rating: 1A

4.5

Cryogen Gas

Two gases may be used, in medical grade only, and both in saturated vapour phase from vapour withdrawal, non-syphon cylinders:Nitrous Oxide (N2O) : boiling point –88.5°C (-127ºF) at STP Carbon Dioxide (CO2) : boiling point –78.4°C (-109ºF) at STP Maximum input pressure : 1000 lbf/in² (70bar) Maximum operating pressure : 750 lbf/in² (51bar), pre-set in manufacture Note: cylinders should be secured in an upright position, but must in no case be at an angle of more than 40° from the vertical.

4.6

Environmental Conditions

4.6.1

OPERATING ENVIRONMENT

ð Temperature :

+10°C to +40°C (50ºF to 104ºF)

Note that the optimum gas cylinder temperature is in the range 20ºC to 25ºC (68ºF to 77ºF)

ð Relative Humidity: 30% to 75% ð Atmos. Pressure: 700 to 1060 hPa (10 to 16 lbf/in²)

4.6.2

STORAGE AND TRANSPORT ENVIRONMENT

ð Temperature : 0°C to +45°C (32ºF to 113ºF) ð Relative Humidity: 15% to 90% (non-condensing) ð Atmos. Pressure: 700 to 1100 hPa (10 to 16 lbf/in²)

__________________________________________________________________________ 4.6

Environmental Conditions (continued)

4.6.3 ELECTROMAGNETIC COMPATIBILITY The CryoStar has been tested for conformance to IEC 601-1-2, Electromagnetic compatibility –

Requirements and tests. However, the user must be aware that other equipment sensitive to electromagnetic radiation may be affected by the CryoStar. Similarly, the CryoStar itself may be affected by other devices, particularly those designed for high frequency diathermy. In normal use, functionality is not affected. It is the operator’s responsibility to ensure that any electromagnetic interference does not compromise the intended surgical procedure.

4.7

Principle of Operation

ð Freezing is achieved by the rapid expansion of high pressure cryogen through a micro-annulus or orifice in the probe tip. This is known as the Joule-Thompson effect. ð Defrosting is achieved by latent heat arising from condensation of cryogen within the cold tip.

__________________________________________________________________________

INSTALLATION

5.1

Unpacking

On unpacking, check the CryoStar for any signs of damage. Check the delivery note for completeness of contents of the packaging. In the event of loss or damage, notify the carrier immediately or contact your supplier. Retain all packaging and shipping cartons.

5.2

Preparation

5.2.1 Needed for successful installation of the CryoStar are:ð mains electricity ð cryogen gas supply ð an exhaust gas scavenging system or suitably vented area. (It is the operator’s responsibility to ensure safe disposal of waste gases.) No custom or special tools are needed. 5.2.2.

Recommended preparation of the cryogen:-

ð Select a full cylinder of gas. An ‘F’ size bottle (3600 litres nominal) should be sufficient for a typical day’s workload. Ensure cylinders are stored at room temperature for 24 hours prior to use. (Note that the optimum gas cylinder temperature is in the range 20ºC to 25ºC.) ð Clean the cylinder’s connection point of all dust, dirt and grease particles. ð Select a suitable adaptor and fit to the gas cylinder, tightening with a spanner. Although not absolutely essential for the unit’s basic function, it is recommended that a filter is fitted to minimise particles or moisture in the gas. Filtering out these impurities will help to prevent the probe clogging and extend the life of the instrument. 5.2.3

Effect of temperature on cryogen cylinders

The pressure available from medical grade N2O and CO2 cylinders depends in part on their temperature. It may be necessary to allow cylinders to warm up to room temperature before use. 20° to 25°C (68° to 77°F) is recommended. Cylinders will cool gradually as cryogen is drawn off and prolonged continuous use may drop the pressure to below a level at which the CryoStar system can work effectively. In this case, either wait for pressure to return or replace with a fresh cylinder, allowing the new cylinder to warm up. Under no circumstances should artificial heat be applied to a cryogen gas cylinder. It is advisable to select the largest cylinder size practicable. A large cylinder should maintain the pressure for longer, although it will take longer to warm up.

5.3

Installation

The CryoStar system should be installed and tested by qualified and authorised personnel. 5.3.1

Connect a high pressure hose from the gas cylinder to the threaded INLET at the rear of the CryoStar console. Use two spanners to ensure a leak-free joint, holding both the hose and the inlet connector, but do not overtighten.

5.3.2

Connect a length of suitable tubing from your scavenging system to the EXHAUST pipe at the rear of the console. Safe disposal of waste gases is the responsibility of the user.

5.3.3

Ensure that your electrical supply is within the range specified by the label on the rear of the console. If ratings differ, do NOT attempt to connect the console. Refer to your supplier.

__________________________________________________________________________ 5.3

Installation (continued)

5.3.4 The equipment must be connected ONLY to a.c. mains power with a protective ground conductor in accordance with IEC regulations. The grounding system must be checked regularly by an authorised technician. Any interruption or disconnection of the ground conductor or terminal may render the equipment dangerous. 5.3.5

Connect the footswitch cable into its socket at the front of the console. The footswitch cable and its connector must be kept dry.

5.3.6

Using the mains cable, connect the electrical supply to the socket at the rear of the console. The cable and its connectors must be kept dry

5.3.7

Check the regulator (at the front of the console) is turned off (fully anti-clockwise).

5.3.8

Press the power switch to ON.

5.3.9

Turn on the gas supply and turn the regulator clockwise until the gas bottle symbol shows three green lights, indicating sufficient pressure.

5.3.10 Insert a probe into the socket at the front of the console and wait approximately 90 seconds for the purge cycle to finish. 5.3.11 Press and hold down the footswitch and re-adjust the regulator, if necessary. Check that the probe tip is freezing. Do not touch the probe tip. 5.3.12 Release the footswitch. The probe should defrost in less than 5 seconds. 5.3.13 Wait for about 20 seconds to allow the console to vent. 5.3.14 Turn OFF the regulator (fully anti-clockwise). 5.3.15 Turn off the gas supply at the cylinder. 5.3.16

Press the power switch to OFF. Installation is now complete. (See next section for Operating or Shut-down instructions.)

__________________________________________________________________________

OPERATING INSTRUCTIONS

It is recommended that a sterile back-up probe be made available for immediate use in the event of any contamination or malfunction during surgery.

6.1

Pre-operative checks

6.1.1 6.1.2

Ensure that installation has been correctly carried out. Check that all hoses, cables and connectors are dry and in good condition and that all connections are secure. Switch ON the power. Open the gas bottle hand valve, open the regulator (turn clockwise) and adjust the pressure into the optimum range. (Refer to the chart at the end of this manual.) With no probe inserted, the freezing indicator display will be off. The time display will show the control system’s software version (eg: P03). The amber ‘busy’ lamp will be on and the green ‘ready’ lamp will be off. The bleeper will sound.

6.1.3 6.1.4

6.2

Using the CryoStar

6.2.1

PURGING

Purging allows cryogen to flow through the probe and clear any residual moisture before use, ensuring optimal performance. It is not intended to clear large amounts of moisture, such as may be present if the probe has not been dried properly or has been sterilised without first fitting the probe plug’s protective cap. ð Screw the cryoprobe plug into the socket at the front of the CryoStar console. ð Wait for the automatic purging sequence to finish (timer counts down to zero, bleeper is heard, ‘busy’ indicator goes off and ‘ready’ indicator comes on). The system is now ready to use. Notes on Purging When a probe is inserted, the purge cycle will begin after a very short delay. Gas is fed through the probe to remove any residual moisture. The probe symbol display will indicate the probe's internal temperature. The purge cycle will start only if the operating pressure has been set to a minimum level. This is adjusted using the pressure regulator. The pressure should be set so that the pressure display has at least one green segment lit. During the purge cycle, which lasts 90 seconds, the time display will count down from 090 to zero. The busy LED will be on and the ready LED will flash. At the end of purging the time display will show 000, the busy LED will be off and the ready LED will be on. The unit will bleep to indicate that it is ready to freeze. During purging, if the operating pressure falls below the minimum purge pressure then the purge timer will stop. Gas may still be flowing but the purge is effectively on hold until the pressure is restored. If the operator urgently needs to remove the probe then the unit may be switched off. The valves will return to their safe, un-powered condition, allowing the internal pressure to vent. The probe connector can then be safely removed. If, during a purge, the unit detects a fault in the probe connection, it will shut down the valves to the safe condition, return to the standby state and wait for a good probe to be inserted or the connection to be otherwise restored. Whenever a probe is removed or the connection is in some way broken, the system will run the purge cycle upon reconnection of a probe.

__________________________________________________________________________ 6.2

Using the CryoStar (continued)

6.2.2

FREEZING

ð Check that the gas operating pressure is set to the optimum range (see probe chart appendix at the back of this manual). ð Wait for the purge cycle to finish. ð Operate the footswitch to check function and using the regulator, re-adjust the pressure into the optimum range. CAUTION: the probe will freeze! ð Check that the displays are showing correctly as described above. ð To freeze, operate the footswitch. Notes on Freezing Freeze cycles may be repeated indefinitely, provided that there is sufficient gas pressure. Freezing is controlled by the footswitch. Whenever the green ‘ready’ lamp is on, the unit is prepared to start a freeze cycle. When the system detects the operation of the footswitch it immediately opens the freeze valve allowing gas to flow through the probe; the probe tip is rapidly cooled. Provided that a thermocouple probe is fitted, the temperature display will change from the ambient range through green to blue. The length of time this takes is of the order of 2 seconds, although this is dependent on a number of physical conditions (including the nature of the tissue surrounding the probe, its temperature and the probe type). The freeze ‘snowflake’ will be lit. When the freeze cycle starts the time display is reset to 000 and it begins counting the freeze time. WARNING Do not attempt to remove the probe connector during freezing. If you urgently need to remove the probe, then first switch off the unit. The valves will return to their safe un-powered condition allowing the internal pressure to vent. The probe connector can then be safely removed. If, during a freeze, the unit detects a fault in the probe connection, it will shut down the valves to the safe condition, return to the standby state and wait for a good probe to be inserted.

6.2.3

DEFROSTING

ð Release the footswitch to defrost. In the unlikely event that the probe fails to defrost, switch off the unit. The probe will thaw slowly as a result of ambient temperature. Notes on Defrosting When the footswitch is released, the freeze timer stops and the unit will bring the probe up to the working pressure set by the regulator. When defrosting is complete, the ‘ready’ indicator lights. The operator may press the footswitch once the ‘ready’ indicator is lit. The freeze cycle restarts. The gas in the probe will vent and then the freezing effect will start again. The system is then running a freeze cycle as described above. (Note: a momentary flicker of the display when the probe vents is quite normal.) The system will allow freezing to be restarted during the defrost period. However, the probe may not have fully defrosted and such action should only be attempted by highly experienced operators.

6.2.4 ð ð ð ð ð

CHANGING CryoStar PROBES

Wait 20 seconds after defrost allowing gas to vent from probe Check that the green ‘ready’ light is on. Unscrew the probe plug (anti-clockwise). The plug should now withdraw. Connect the new probe. Wait for the replacement probe to purge automatically.

__________________________________________________________________________ 6.3 ð ð ð ð ð ð ð ð

6.4

Shut-down Wait 20 seconds after defrost allowing gas to vent from probe. Check that the green ‘ready’ light is on. Unscrew the probe plug (anti-clockwise). The plug should now withdraw Close the hand valve on the gas cylinder. Turn the regulator anti-clockwise to its minimum position. Vent the system by rotating the console’s regulator a number of times in both directions. Switch OFF the power. Should you wish to remove the supply hose, be aware that residual pressure may still be present in the system. Using two spanners (one for the hose and one for the connector), loosen the hose connector (at the console) very gently until gas can be heard, then slacken the connector a bit more (less than a full turn) and wait for gas to finish venting off. [CAUTION: Do not use this method unless in well-ventilated area!]

Changing cylinders

The cryogen cylinder should be exchanged when it is no longer possible to open the regulator far enough to obtain three green indicators on the ‘gas bottle’ symbol. Follow the shut-down procedure (above). Disconnect the high pressure hose on the cylinder. Remove the adaptor from the cylinder. Clean the adaptor and fit it to the replacement cylinder. (Recommended: Install a new moisture filter into the adaptor.) ð Reconnect the high pressure hose. ð Follow the procedure for pre-operative checks. ð ð ð ð

6.5

Using the probe adaptor

The probe adaptor allows older style probes to be used with the CryoStar console. Simply connect the probe into the screw fitting at the front of the adaptor and fit the adaptor’s flying lead into the console. Use the settings described in the chart at the end of this manual.

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DORC

Cryosurgery Units

CryoStar Operator’s Manual issue C208-2