3.1 Local cryostimulation
Local cryotherapy treatment uses usually the following cryogens: liquid nitrogen, carbon
dioxide, cooled air [Sieroń & Cieslar 2003]. Prior to cryostimulation, the patient should
thoroughly dry the body surface to be subjected to treatment. It is most desirable to keep the
patient in a standing position or if not possible, in a sitting or lying position. Procedure
duration is defined individually for each patient, depending also on the body structure,
muscle mass and fat thickness. Cryotherapy is not used for more than about 5 joints at the
same time which should not be longer than 12-15 minutes. The hand, foot and spine are
considered as a single set of small joints [Księżopolska - Pietrzak 1998].
The treatment time takes usually from 30 sec to several minutes (3-4 min), depending on the
patient's skin response. The treatment may be repeated twice a day but with a break of at
least 6 hours. The recommended duration of the break is determined by the sustained
stimulatory effect after a single session. In children, treatment should be used very
cautiously and of a shorter duration than adults due to the higher sensitivity of the younger
skin and usually lower amount of subcutaneous fat. The distance of a cryoapplicator from
the surface of the body depends on the quality of the device, and the temperature obtained
at the nozzle exit, usually about 10 cm from the body surface (in older devices, the distance
can be up to 15 cm). The treatment area of the body should be progressively swept over to
avoid cooling of just one spot. Initially the patients experience a burning sensation. The
patient must stay in communication with the physiotherapist and inform him about the pain
or the burning sensation. After reported discomfort the applicator should be positioned
further from the tissue, or the movement of the nozzle should be sped up. Rapid skin
blanching is an indicator for immediate cessation of the treatment [Jezierski 2006].
During cryotherapy, one must remember about the bi-phasic vascular response to extremely
low temperatures, and bear in mind the desired effect. Initially, in micro-circulation, a
constriction of vessels as a result of closing of pre-capillary sphincter and activation of
arteriovenous anastomoses, which takes from a few to a ten or so seconds, after which the
vessels dilate and arteriovenous anastomoses close, during which blood flow increases. A
lower temperature of the coolant (liquid nitrogen vapour) results in a stronger and faster
first stage, i.e. vasoconstriction causing tissue ischemia. In this way one can reduce the
effects of trauma, reduce the rate of metabolic processes (which may be helpful for example
in the physical therapy of arthritis), while hypoxia reduces perceived pain. In the second
phase, local hyperaemia occurs (increase in local blood flow due to the effect of internal and
external factors, known as the rebound effect), during which metabolic processes are
intensified and muscle tension is reduced.