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User
Manual Cryo- Jet |
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User Manual
Cryo-Jet
MAXI/MINI
FILLING THE UNIT
The
Cryo-Jet unit is to be filled with liquid nitrogen
only. Fill the unit by slowly pouring liquid nitrogen
into the top or by using a standard low pressure
withdrawal device from a storage tank (dewar).
Depending on the number of lesions to be treated
and the duration of the individual treatments
the unit should be filled to 25 - 90 % of its
maximum capacity.
We recommend the unit to be approx. 70 % filled
for a 6 - 8 hour duration of intermittent use.
After filling a warm unit, the liquid will boil
violently for approx. 30 secs. Hereafter, the
top cover can easily be replaced. Caution should
be taken when refilling a Cryo-Jet containing
residual fluid as the unit is pressurized at 0.7
bar (10 psi). Slowly unscrewing the top cover
will allow the unit to depressurize before the
top comes off. This is accompanied by an audible
hissing sound until it is fully depressurized. |
OPERATION
| The
Cryo-Jet is supplied with a set of standard spray
apertures. Optional closed probes are available
for contact freezing. All probes and spray apertures
are screwed into the permanently affixed knurled
nut with finger tight firmness. Do not apply excessive
force.
Do never use the Cryo-Jet without either a spray
aperture or closed probe in place. The excessive
amount of liquid put out if the unit is used without
spray or probe attachment will cause severe damage
to the patient |
Spray freezing
The
standard spray apertures consist of: “A” (1 mm
opening) and “B” (0.70 mm opening) for large and
deep lesions or for superficial desquamation of
skin; 2 X “C” (0.6 mm recommended for warts and
keratoses; “D” (0.50 mm opening) for small warts
and keratolytic lesions.
Finally, the “Bent Spray” aperture(0.5 mm opening)
is for areas difficult to reach like behind the
ears, lip and outer nose (avoiding gas into the
airways). Select a spray aperture appropriate
for the lesion to be treated In-depth freezing
is best obtained when the spray aperture is close
to the lesion (5 - 10 mm distance) as the liquid
content of the spray is higher close to the aperture.
When possible, raised warts should be approched
tangientally from at least two sides. This allows
the ice ball to move down through the wart while
sparing the surrounding tissue.
Spraying directly at the lesion (perpendicular
to the surface) will cause more lateral spread
with less penetration. To avoid this apply the
spray intermittently or use a smaller spray aperture.
Superficial desquamation is obtained using the
larger apertures (“A” or “B”) at approx. 5 cm
distance (higher vapor content) and slowly “painting”
the surface with Vaporized nitrogen. Aperture
E ( 0.8 mm ) ,G ( 0.9 mm ) & H (1.1 mm ) are
Optional. |
Contact freezing
Closed
contact probes provide in-depth freezing with
minimal lateral spread. Select a probe size fitting
the size of the lesion. Make the lesion wet with
a drop of water or contact gel prior to freezing
to facilitate the thermal transfer between skin
and probe tip. Apply the contact probe when still
warm applying light pressure and pull the trigger
handle. Allow approx. 5 sec. extra freezing time
to cool down the contact probe and keep freezing
until a 1 mm halo is seen around the probe tip.
Then stop the freezing and allow a few seconds
for the probe tip to come loose. ”This quick freeze
slow thaw” procedure using the. contact probe
technique ensures a very effective treatment with
high penetration and accuracy. Freezing times
vary according to the aperture or probe used,
the size and type of the lesion and the freezing
distance (spray only). The user is encouraged
to familiarize himself with available literature
on cryosurgery using liquid nitrogen. |
AFTER USE
| At the end of an office day it is
highly recommended to store the Cryo- Jet with the
lid on in order to prevent condensation inside the
bottle. Build-up of condensation may lead to clogging
of the valve assembly. |
MAINTENANCE
| No preventive maintenance
is needed. |
STERILIZATION
| Normally,
spray apertures need no sterilization as they
are not in contact with the patient. However,
should the need for sterilization arise, the same
procedure as for closed contact probes can be
followed. Closed contact probes are in direct
contact with the patient and should always be
sterilized after use. The recommended method for
sterilization is steam autoclaving at 121 deg.c
for 15 min. |
WARNINGS
• Do never use the Cryo-Jet
unit without a spray aperture or closed contact
probe in place.
• The Cryo-Jet is supposed to be held in a vertical
position when used. Liquid nitrogen may escape
through the relief valve if the unit is held in
a position allowing the liquid inside the bottle
to be in contact with the lid. Return the unit
to a more upright position if liquid starts coming
out of the relief valve. The maximum working angle
depends on the amount of liquid nitrogen in the
bottle.
• Be careful when opening a pressurized unit.
Unscrew the top slowly. The unit may still be
pressurized even if there is no residual liquid
left.
• The Cryo-Jet is a surgical instrument. When
not in use it must be kept out of reach of children
and unauthorized personnel. |
STORING LIQUID NITROGEN
To ensure a clean supply
of liquid nitrogen the storage tank (dewar) must
be complete emptied prior to refilling 3 - 4 times
per year. If necessary, water from icecrystals
remaining inside the tank can be dried out by
creating air circulation (e.g. using a vacuum
cleaner for approx. 15 min). |
SUGGESTED LITERATURE
•
Dawber, Colver, Jackson: Cutaneous Cryosurgery,
Principles and Clinical Practice (Martin Duniti
ISBN 1 85317 082 8).
• Kuflik, Gage: Cryosurgical Treatment For Skin
Cancer (Igaku- Shoin ISBN 0 89640 157 X) E.M.D.
Co |
| FIGURE 1. Cryosurgery
devices. (Left)Cotton-tip applicator. (Center) Liquid
nitrogen spray. (Right) Cryoprobe. |
| FIGURE 2.
Liquid nitrogen spray patterns. |
| FIGURE 3.
Liquid nitrogen spray application using a timed
spot freeze technique and an open cone shield to
direct the liquid nitrogen (note that an otoscope
tip can be used with similar effect). The spray
nozzle is positioned approximately 1 to 1.5 cm above
the target lesion. |
| FIGURE 4.
Timed spot freeze technique used to treat a malignancy
( possibly a small basal cell cancer ), demonstrating
freeze ball formation and the 5 mm treatment margins
necessary to achieve a temperature of 150 C ( 258
F ) and ,thus, the required depth of 4 to 5 mm. |
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